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ABSTRACT |
IEEE YEAR |
PE01 | A Current Controller Design for Current Source Inverter-Fed AC Machine Drive System | Abstract—A current source inverter (CSI) requires a capacitor filter for the commutation of switching device as well as for attenuating switching harmonics. Hence, the CSI-fed ac machine has a second-order system in the continuous time domain. This paper presents a design methodology for the closed-loop current controller of the CSI-fed ac machine drive system. A multiloop current controller design using a pole/zero cancellation method is employed with a transfer function matrix. To decouple the crosscoupling terms which cause mutual interferences between the dand q-axes in the synchronous reference frame, two types of controller are proposed and implemented using different decoupling method. Additionally, active damping methods are incorporated to enhance the stability of the system. A stability analysis in discretetime domain is investigated to verify the feasibility of the proposed closed-loop current controller. To evaluate the effectiveness of the proposed current controller, computer simulations and experimental tests were performed and the results are discussed. | IEEE 2013 |
PE02 | A DC–DC Converter Based on the Three-State Switching Cell for High Current and Voltage Step-Down Applications | Abstract—This paper presents a pulsewidth modulation dc–dc nonisolated buck converter using the three-state switching cell, constituted by two active switches, two diodes, and two coupled inductors. Only part of the load power is processed by the active switches, reducing the peak current through the switches to half of the load current, as higher power levels can then be achieved by the proposed topology. The volume of reactive elements, i.e., inductors and capacitors, is also decreased since the ripple frequency of the output voltage is twice the switching frequency. Due to the intrinsic characteristics of the topology, total losses are distributed among all semiconductors. Another advantage of this converter is the reduced region for discontinuous conduction mode when compared to the conventional buck converter or, in other words, the operation range in continuous conduction mode is increased, as demonstrated by the static gain plot. The theoretical approach is detailed through qualitative and quantitative analyses by the application of the three-state switching cell to the buck converter operating in nonoverlapping mode (D < 0.5). Besides, the mathematical analysis and development of an experimental prototype rated at 1 kW are carried out. The main experimental results are presented and adequately discussed to clearly identify its claimed advantages. | IEEE 2013 |
PE03 | A High Step-Down Transformerless Single-Stage Single-Switch AC/DC Converter | Abstract—This paper presents a high step-down tranformerless single-stage single-switch ac/dc converter suitable for universal line applications (90–270 Vrms ). The topology integrates a buck-type power-factor correction (PFC) cell with a buck–boost dc/dc cell and part of the input power is coupled to the output directly after the first power processing. With this direct power transfer feature and sharing capacitor voltages, the converter is able to achieve efficient power conversion, high power factor, low voltage stress on intermediate bus (less than 130 V) and low output voltage without a high step-down transformer. The absence of transformer reduces the component counts and cost of the converter. Unlike most of the boost-type PFC cell, the main switch of the proposed converter only handles the peak inductor current of dc/dc cell rather than the superposition of both inductor currents. Detailed analysis and design procedures of the proposed circuit are given and verified by experimental results. | IEEE 2013 |
PE04 | A High Step-Up Converter With a Voltage Multiplier Module for a Photovoltaic System | Abstract—Anovel high step-up converter is proposed for a frontend photovoltaic system. Through a voltage multiplier module, an asymmetrical interleaved high step-up converter obtains high stepup gain without operating at an extreme duty ratio. The voltage multiplier module is composed of a conventional boost converter and coupled inductors. An extra conventional boost converter is integrated into the first phase to achieve a considerably higher voltage conversion ratio. The two-phase configuration not only reduces the current stress through each power switch, but also constrains the input current ripple, which decreases the conduction losses of metal–oxide–semiconductor field-effect transistors (MOSFETs). In addition, the proposed converter functions as an active clamp circuit, which alleviates large voltage spikes across the power switches. Thus, the low-voltage-rated MOSFETs can be adopted for reductions of conduction losses and cost. Efficiency improves because the energy stored in leakage inductances is recycled to the output terminal. Finally, the prototype circuit with a 40-V input voltage, 380-V output, and 1000- W output power is operated to verify its performance. The highest efficiency is 96.8%. | IEEE 2013 |
PE05 | A High-Performance SPWM Controller for Three-Phase UPS Systems Operating Under Highly Nonlinear Loads | Abstract—This paper presents the design of a high-performance sinusoidal pulsewidth modulation (SPWM) controller for threephase uninterruptible power supply (UPS) systems that are operating under highly nonlinear loads. The classical SPWM method is quite effective in controlling the RMS magnitude of the UPS output voltages. However, it is not good enough in compensating the harmonics and the distortion caused specifically by the nonlinear currents drawn by the rectifier loads. The distortion becomes more severe at high power where the switching frequency has to be reduced due to the efficiency concerns. This study proposes a new design strategy that overcomes the limitations of the classical RMS control. It adds inner loops to the closed-loop control system effectively that enables successful reduction of harmonics and compensation of distortion at the outputs. Simulink is used to analyze, develop, and design the controller using the state-space model of the inverter. The controller is implemented in the TMS320F2808 DSP by Texas Instruments, and the performance is evaluated experimentally using a three-phase 10 kVA transformer isolated UPS under all types of load conditions. In conclusion, the experimental results demonstrate that the controller successfully achieves the steady-state RMS voltage regulation specifications as well as the total harmonic distortion and the dynamic response requirements of major UPS standards. (Index Terms—Inverter, nonlinear load, sinusoidal pulsewidth modulation (PWM) control, uninterruptible power supply (UPS).) | IEEE 2013 |
PE06 | A New Control Method of Interleaved Single-Stage Flyback AC–DC Converter for Outdoor LED Lighting Systems | Abstract—In outdoor light-emitting diode (LED) lighting systems, there are a lot of applications. Depending on the output power rating, the power stage to drive an LED can be classified into single-stage and two-stage structures. The single-stage structure is for low-power LED lighting applications. However, it is difficult to apply at over 60–70 W of output power because of its low efficiency and huge transformer at high power. On the other hand, the two-stage structure is usually used for high power applications. However, it is undesirable to cover wide output power range because of its poor power factor (PF) under the light load condition. To solve these problems, this paper proposes a new pulse duty cycle control method with pulse frequency modulation for an interleaved single-stage flyback ac–dc converter. The proposed converter provides high efficiency under heavy loads with low ac line condition and under light loads with high ac line condition. In addition, the proposed converter shows high PF and low total harmonic distortion even when the output power is very low. As a result, a single LED ac–dc converter can cover wide power range for outdoor LED lighting applications. To verify the validity of the proposed converter, an 81-W prototype converter has been implemented and experimented on. (Index Terms—Frequency control, interleaved flyback, lightemitting diode (LED), power factor correction (PFC), single-stage, total harmonic distortion (THD).) | IEEE 2013 |
PE07 | A New DC Anti-Islanding Technique of Electrolytic Capacitor-Less Photovoltaic Interface in DC Distribution Systems | Abstract—This paper proposes a photovoltaic (PV) generation system interfaced with a dc distribution system. DC interface allows for the improvement of system efficiency by fully utilizing dc-based renewable sources and storage devices. In this paper,issues on PV interface for dc distribution systems are discussed for energy-efficient and reliable system implementation. AC and dc PV interfaces are mathematically analyzed. In dc distribution, eliminating electrolytic capacitors in PV interfaces improves system reliability, increases system efficiency, and reduces cost. In addition, this paper proposes a new anti-islanding technique for dc distribution as a system protection scheme. The operating principle is presented in detail and analysis shows that the proposed injected current perturbation technique is an effective solution for anti-islanding operation. A prototype converter features a simple structure with no electrolytic capacitor, which ensures a longer lifetime of the PV power circuit. Experimental results of the prototype circuit show a maximum efficiency of 98.1% and a European efficiency of 97.5%. The proposed anti-islanding technique shows fast response to the islanding condition in less than 0.2 s. It also shows that the average maximum power point tracking efficiency is 99.9% in normal conditions, which verifies the performance of the proposed scheme. (Index Terms—Anti-islanding, building integrated photovoltaic (BIPV), dc distribution, islanding, photovoltaic (PV).) | IEEE 2013 |
PE08 | A Single-Phase Grid-Connected Fuel Cell System Based on a Boost-Inverter | Abstract—In this paper, the boost-inverter topology is used as a building block for a single-phase grid-connected fuel cell (FC) system offering low cost and compactness. In addition, the proposed system incorporates battery-based energy storage and a dc–dc bidirectional converter to support the slow dynamics of the FC. The single-phase boost inverter is voltage-mode controlled and the dc–dc bidirectional converter is current-mode controlled. The low-frequency current ripple is supplied by the battery whichminimizes the effects of such ripple being drawn directly from the FC itself.Moreover, this system can operate either in a grid-connected or stand-alone mode. In the grid-connected mode, the boost inverter is able to control the active (P) and reactive (Q) powers using an algorithm based on a second-order generalized integrator which provides a fast signal conditioning for single-phase systems. Design guidelines, simulation, and experimental results taken from a laboratory prototype are presented to confirm the performance of the proposed system. (Index Terms—Boost inverter, fuel cell, grid-connected inverter, power conditioning system (PCS), PQ control.) | IEEE 2013 |
PE09 | A Three-Level Converter With Reduced Filter Size Using Two Transformers and Flying Capacitors | Abstract—This paper proposes a pulse-width modulation threelevel converter with reduced filter size using two transformers. The proposed converter hasmany advantages. All switches sustain only the half of the input voltage and since the secondary rectified voltage is a three-level waveform, the output filter inductor can be reduced. Also, because of the power sharing of transformer and reduced output inductor, high efficiency can be obtained. The operational principle, analysis, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from a prototype with 600W, 500–600V input, and 60V output. (Index Terms—Reduced filter size, three-level converter.) | IEEE 2013 |
PE10 | Adaptive Dead-Time Compensation for Grid-Connected PWM Inverters of Single-Stage PV Systems | Abstract—This study presents a new software-based plug-in dead-time compensator for grid-connected pulsewidth modulated voltage-source inverters of single-stage photovoltaic (PV) systems using predictive current controllers (PCCs) to regulate phase currents. First, a nonlinear dead-time disturbance model is reviewed, which is then used for the generation of a feed-forward compensation signal that eliminates the current distortion associated with current clamping effects around zero-current crossing points. A novel closed-loop adaptive adjustment scheme is proposed for fine tuning in real time the compensation model parameters, thereby ensuring accurate results even under the highly varying operating conditions typically found in PV systems due to insolation, temperature, and shadowing effects, among others. The algorithm implementation is straightforward and computationally efficient, and can be easily attached to an existent PCC to enhance its dead-time rejection capabilitywithout modifying its internal structure. Experimental results with a 5-kW PV system prototype are presented. (Index Terms—Current-controlled voltage-source inverter (CCVSI), dead-time compensation, grid-connected pulsewidth modulated (PWM) inverter, harmonic distortion, predictive current control (PCC), single-stage photovoltaic (PV) system.) | IEEE 2013 |
PE11 | Adaptive Theory-Based Improved Linear Sinusoidal Tracer Control Algorithm for DSTATCOM | Abstract—This paper presents a hardware implementation of three-phase distribution static compensator (DSTATCOM) using an adaptive theory-based improved linear sinusoidal tracer (ILST) control algorithm for different functions of DSTATCOM such as reactive power compensation for power factor correction, harmonics elimination, load balancing, and zero-voltage regulation under linear/nonlinear loads.AnILST-based control algorithm is used for the extraction of fundamental load currents and their active and reactive power components. These components are used for the estimation of reference source currents. A prototype of DSTATCOM is developed and its real-time performance is studied using a digital signal processor. The performance of DSTATCOM is found satisfactory with the proposed control algorithm under various types of loads. (Index Terms—Improved linear sinusoidal tracer (ILST) control algorithm, power factor correction (PFC), power quality, reactive power, voltage source converter (VSC), zero voltage regulation (ZVR).) | IEEE 2013 |
PE12 | Adaptive Voltage Control of the DC/DC Boost Stage in PV Converters With Small Input Capacitor | Abstract—In the case of photovoltaic (PV) systems, an adequate PV voltage regulation is fundamental in order to both maximize and limit the power. For this purpose, a large input capacitor has traditionally been used. However, when reducing that capacitor’s size, the nonlinearities of the PV array make the performance of the voltage regulation become highly dependent on the operating point. This paper analyzes the nonlinear characteristics of the PV generator and clearly states their effect on the control of the dc/dc boost stage of commercial converters by means of a linearization around the operating point. Then, it proposes an adaptive control, which enables the use of a small input capacitor preserving at the same time the performance of the original system with a large capacitor. Experimental results are carried out for a commercial converter with a 40 μF input capacitor, and a 4 kWPV array. The results corroborate the theoretical analysis; they evidence the problems of the traditional control, and validate the proposed control with such a small capacitor. (Index Terms—Adaptive control, photovoltaic converters, photovoltaic power systems, small-signal modeling, voltage control.) | IEEE 2013 |
PE13 | An Adaptive Output Current Estimation Circuit for a Primary-Side Controlled LED Driver | Abstract—A primary-side controlled method is commonly used in flyback LED driver to regulate output current by employing an auxiliary winding. However, owing to intrinsic propagation delay in real-world circuits, a primary-side controlled flyback converter experiences a worse line regulation. This paper proposes a smart output current estimation scheme to improve line regulation for constant on-time control, and it can be compatible with the current flyback topology. A 9.5-W prototype of the proposed flyback LED driver has been fabricated in Nuvoton Technology Corporation 0.6-μm 5-V/40-V CMOS process. The maximum switching frequency is set to around 100 kHz with universal-line input, single-stage power factor correction for LED lighting applications. Experimental results prove that the proposed scheme can improve the line regulation within 1.5% and the power efficiency can be up to 89.7%. (Index Terms—Flyback converter, light-emitting diode (LED) driver, line regulation, primary-side controlled.) | IEEE 2013 |
PE14 | An Optimal Control Method for Photovoltaic Grid-Tied-Interleaved Flyback Microinverters to Achieve High Efficiency in Wide Load Range | Abstract—Boundary conduction mode (BCM) and discontinuous conduction mode (DCM) control strategies are widely used for the flyback microinverter. The BCM and DCM control strategies are investigated for the interleaved flyback microinverter concentrating on the loss analysis under different load conditions. These two control strategies have different impact on the loss distribution and thus the efficiency of the flyback microinverter. For the interleaved flyback microinverter, the dominant losses with heavy load include the conduction loss of the powerMOSFETs and diodes, and the loss of the transformer; while the dominant losses with light load include the gate driving loss, the turn-off loss of the power MOSFETs and the transformer core loss. Based on the loss analysis, a new hybrid control strategy combing the two-phase DCM and one-phaseDCMcontrol is proposed to improve the efficiency in wide load range by reducing the dominant losses depending on the load current. The optimal design method based on the boundary condition of the hybrid control is also presented. The experimental results verify the benefits of the proposed control. (Index Terms—AC module, grid-connected, interleaved flyback, microinverter, photovoltaic (PV).) | IEEE 2013 |
PE15 | Analysis and Comparison of Medium Voltage High Power DC/DC Converters for Offshore Wind Energy Systems | Abstract—Offshore wind farm with an internal medium-voltage dc (MVDC)-grid collection connected HVDC transmission may be an option to harvest offshore wind energy. High-power MV dc/dc converters with high-step-up conversion ratios are the key components for the internal MVDC grid. In this paper, a highefficiency step-up resonant switched-capacitor converter for offshore wind energy system is studied, which is characterized by the soft-switching condition for all switches and diodes. This significantly reduces switching losses and higher switching frequency is feasible to reduce the overall system volume and weight. The comparisons with other two kinds of topologies are also presented; moreover, the possible specification requirements of high power MV dc/dc converters are analyzed and set. The operation principle of the proposed converter has been successfully verified by simulation and experiment results. (Index Terms—High power, medium-voltage dc (MVDC) converter, MVDC grid, offshore wind farm.) | IEEE 2013 |
PE16 | Analysis and Design of a Push–Pull Quasi-Resonant Boost Power Factor Corrector | Abstract—This paper proposes a novel power-factor corrector (PFC), which is mainly composed of two-phase transition-mode (TM) boost-type power-factor correctors (PFCs) and a coupled inductor. By integrating two boost inductors into one magnetic core, not only the circuit volume is reduced, but also the operating frequency of the core is double of the switching frequency. Comparing with single-phase TM boost PFC, both the input and output current ripples of the proposed PFC can be reduced if the equivalent inductance of the coupled inductor equals the inductance of singlephase TM boost PFC. Therefore, both the power-factor value and the power density are increased. The proposed topology is capable of sharing the input current and output current equally. A cut-inhalf duty cycle can reduce the conduction losses of the switches and both the turns and diameters of the inductor windings. The advantages of aTMboost PFC, such as quasi-resonant (QR) valley switching on the switch and zero-current switching (ZCS) of the output diode, are maintained to improve the overall conversion efficiency. Detailed analysis and design procedures of the proposed topology are given. Simulations and experiments are conducted on a prototype with a universal line voltage, a 380-V output dc voltage and a 200-W output power to verify its feasibility. (Index Terms—Coupled inductor, power factor corrector, push– pull topology, quasi-resonant (QR) converter.) | IEEE 2013 |
PE17 | Analysis of a Fifth-Order Resonant Converter for High-Voltage DC Power Supplies | Abstract—Power transformer is one of the most complex parts of power converters. The complicated behavior of the transformer is usually neglected in the power converter analysis and a simple model is mostly used to analyze the converter. This paper presents a precise analysis of a fifth-order resonant converter which has incorporated the resonant circuit into the transformer. The derived model, which is based on the accurate model of the power transformer, can fully predict the behavior of the fifth-order resonant converter. The proposed fifth-order resonant converter is able to effectively reduce the range of phase-shift angle fromno load to full load for a fixed-frequency phase-shift control approach. Therefore, the converter is able to operate under zero voltage switching during entire load range with a fixed-frequency control method. Also, the proposed converter offers a high gain which leads to a lower transformer turns ratio. A 10-kVDC, 1.1-kW prototype has been prepared to evaluate the performance of the proposed converter. The experimental results exhibit the excellent accuracy of the proposed model and the superiority of the performance compared to the lower order resonant converters, especially for high-voltage applications. (Index Terms—Fifth-order resonant converter, high-voltage dc power supply, phase-shift fixed-frequency control approach, steady state analysis, zero voltage switching (ZVS) operation.) | IEEE 2013 |
PE18 | Analysis, Design, and Experimental Results of a Novel Soft-Switching Snubberless Current-Fed Half-Bridge Front-End Converter-Based PV Inverter | Abstract—This paper proposes a new novel snubberless currentfed half-bridge front-end isolated dc/dc converter-based inverter for photovoltaic applications. It is suitable for grid-tied (utility interface) as well as off-grid (standalone) application based on the mode of control. The proposed converter attains clamping of the device voltage by secondary modulation, thus eliminating the need of snubber or active-clamp. Zero-current switching or natural commutation of primary devices and zero-voltage switching of secondary devices is achieved. Soft-switching is inherent owing to the proposed secondary modulation and is maintained during wide variation in voltage and power transfer capacity and thus is suitable for photovoltaic (PV) applications. Primary device voltage is clamped at reflected output voltage, and secondary device voltage is clamped at output voltage. Steady-state operation and analysis, and design procedure are presented. Simulation results using PSIM 9.0 are given to verify the proposed analysis and design. An experimental converter prototype rated at 200 W has been designed, built, and tested in the laboratory to verify and demonstrate the converter performance over wide variations in input voltage and output power for PV applications. The proposed converter is a true isolated boost converter and has higher voltage conversion (boost) ratio compared to the conventional active-clamped converter. (Index Terms—Current-fed converter, high frequency, photovoltaic (PV) inverter, renewable energy system, soft-switching.) | IEEE 2013 |
PE19 | Application and Stability Analysis of a Novel Digital Active EMI Filter Used in a Grid-Tied PV Microinverter Module | Abstract—This paper presents a novel technique to suppress common-mode electromagnetic interference (EMI) using a digital active EMI filter (DAEF). The DAEF control technique is concurrently implemented with a digital controller of a grid-tied photovoltaic microinverter. A brief description of the microinverter architecture and its inverter circuit is illustrated. The inverter stability is investigated using the overall transfer function. Accordingly, the system compensation is designed based on the direct quadrant (DQ) reference frame control technique. Finally, the proposed digital controller is tested on a grid-connected 200-W dc–ac microinverter. The experiment results validate the effectiveness of the proposed technique. Compared with the conventional passive EMIfilter, the proposed digital controller can achieve an equivalent or better performance in terms of EMI suppression and maintain stability within the operation bandwidth. Therefore, the embedded DAEF can significantly reduce the size, cost, and space of the overall power inverter printed circuit board without the need of a conventional passive EMI filter. (Index Terms—Digital filters, electromagnetic compatibility (EMC), electromagnetic interference (EMI) suppression, microinverter, photovoltaic (PV).) | IEEE 2013 |
PE20 | Asymmetric Control of DC-Link Voltages for Separate MPPTs in Three-Level Inverters | Abstract—It is important to improve the overall efficiency of a photovoltaic (PV) inverter when it is connected to the grid. Fundamentally, the conversion efficiency from dc to ac power of an inverter is important. However, in the presence of partial shading, maximum power point tracking (MPPT) on PV modules is more important than the conversion efficiency. In this paper, a new control method for a three-level inverter is proposed.With the proposed method, each dc-link voltage of the three-level inverter can be asymmetrically regulated. When PV modules are split into two and each split module is connected to the respective dc-link capacitors of the inverter, the asymmetric control can be helpful because separateMPPTs are possible. The effectiveness of the proposed method was examined through experiments with a T-type three-level inverter, where each dc-link capacitor was supplied by a PVsimulator emulating two separate PVmodules under different shading conditions. (Index Terms—Asymmetric voltage control, grid-connected inverter, maximum power point tracking (MPPT), photovoltaic (PV), three-level inverter.) | IEEE 2013 |
PE21 | Battery/Supercapacitors Combination in Uninterruptible Power Supply (UPS) | Abstract—This study presents a study of the reduction in battery stresses by using supercapacitors (SCs) in a 500-kVA rated UPS. We aim at investigating the optimal supercapacitors-battery combination versus the SCs cost. This investigation is threefold; first, supercapacitors and battery models developed using MATLAB/Simulink are presented and validated. Second, the architecture and the simulation of the designed system that combines the SCs and the battery are shown. The supercapacitors are used as high-power storage devices to smooth the peak power applied to the battery during backup time and to deliver full power during short grid outages. By charging the SCs through the battery at a suitable rate, all impulse power demands would be satisfied by the supercapacitors. Third, extensive simulations are carried out to determine the gain in batteryRMS current, the gain in energy losses, the energy efficiency and the elimination rate of surge load power. These four performance parameters are determined by simulation and then analyzed. The influence of the SCs recharge on the performance indicators is highlighted. A thorough analysis involving optimal study proposes to draw the optimal SCs number and filter constant from the variation of the aforementioned parameters versus the cost of the SCs. (Index Terms—Hybrid power sources, lead-acid battery, supercapacitors, uninterruptible power supply (UPS).) | IEEE 2013 |
PE22 | Bridgeless SEPIC Converter With a Ripple-Free Input Current | Abstract—Conventional power factor correction (PFC) singleended primary inductor converter (SEPIC) suffers from high conduction loss at the input bridge diode. To solve this problem, a bridgeless SEPIC converter with ripple-free input current is proposed. In the proposed converter, the input bridge diode is removed and the conduction loss is reduced. In addition, the input current ripple is significantly reduced by utilizing an additional winding of the input inductor and an auxiliary capacitor. Similar to the conventional PFC SEPIC converter, the input current in a switching period is proportional to the input voltage and near unity power is achieved. The operational principles, steady-state analysis, and design equations of the proposed converter are described in detail. Experimental results from a 130Wprototype at a constant switching frequency of 100 kHz are presented to verify the performance of the proposed converter. (Index Terms—Bridgeless converter, coupled inductor, power factor correction (PFC), single-ended primary inductor converter (SEPIC).) | IEEE 2013 |
PE23 | Cascaded Multicell Trans-Z-Source Inverters | Abstract—Inverters with high-output voltage gain usually face the problem of high-input current flowing through their components. The problem might further be exaggerated if the inverters use high-frequency magnetic devices like transformers or coupled inductors. Leakage inductances of these devices must strictly be small to prevent overvoltages caused by switching of their winding currents. To avoid these related problems, cascaded trans-Z-source inverters are proposed. They use multiple magnetic cells in an alternately cascading pattern rather than a single magnetic cell with large turns ratio. Simulation and experimental results have shown that the multicell inverters can produce the same high-voltage gain, while keeping currents and voltages of the components low. The inverters can also step down their output voltages like a traditional voltage-source inverter without compromising waveform quality. (Index Terms—Cascaded inverters, coupled inductors, highfrequency magnetic, transformers, Z-source inverters.) | IEEE 2013 |
PE24 | Class-D/DE Dual-Mode-Operation Resonant Converter for Improved-Efficiency Domestic Induction Heating System | Abstract—Induction heating (IH) technology is nowadays widely present in domestic appliances because of its cleanness, high efficiency, and faster heating process. All of these advantages are due to its heating process, where the pot is directly heated by the induced currents generatedwith a varyingmagnetic field.As a result, the glass where the pot is supported is not directly heated and, consequently, efficiency and heating times are improved. IH systems are based on dc-link inverters to generate the required alternating current to feed the inductor. Usually, resonant converters are used to achieve higher efficiencies and power densities. In such systems, themaximum output power and efficiency are achieved at the resonant frequency, and the switching frequency is increased to reduce the output power. As a consequence, in these converters, the efficiency is also reduced in the low-medium output power range. This paper proposes the use of the half-bridge inverter in two operating modes to achieve higher efficiency in a wide output power range. The power converter topology can be reconfigured by changing the resonant capacitors through electromechanical relays. As a consequence, the entire efficiency of the cooking process is improved with a cost-effective procedure.(Index Terms—Induction heating (IH), inverter, resonant power conversion.) | IEEE 2013 |
PE25 | Common-Mode Voltage Reduction Methods for Current-Source Converters in Medium-Voltage Drives | Abstract—Common-mode voltages (CMVs) can lead to premature failure of the motor insulation system in medium-voltage current-source-fed drives. By analyzing the CMV values at all switching states under different operating conditions of a currentsource-inverter (CSI)-based motor drive, this paper first indicates that the CMV peaks are produced by the zero states in most of the cases. The nonzero-state (NZS) modulation techniques employed in voltage-source converters are adapted for use in a spacevector- modulated current-source converter (CSC) to reduce the CMV magnitude. For NZS modulation in CSCs, the nearest threestate (NTS) modulation sequences are designed with good loworder harmonic performances in their linear modulation region of ma ≥ 0.67 and with no increase in the device switching frequency. A combined active-zero-state (AZS) modulation technique is also proposed as compensation, for a lower modulation index in the range of 0.4–0.67, when a compromise is made between the dc-link current minimization and high input power factor control. The simulation and experimental results are provided to validate the CMV reduction effects and harmonic performances of the NTS and combined AZS modulation methods in CSI-fed drives. (Index Terms—Active-zero-state (AZS) modulation, commonmode voltage (CMV), current-source converter (CSC), nearest three-state (NTS) modulation, nonzero-state (NZS) modulation.) | IEEE 2013 |
PE26 | Control of Improved Full-Bridge Three-Level DC/DC Converter for Wind Turbines in a DC Grid | Abstract—This paper presents an improved full-bridge threelevel (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of thewind turbine based on the IFBTL dc/dc converter in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis. (Index Terms—DC/DC converter, dc grid, full-bridge three-level (FBTL), permanentmagnet synchronous generator, wind turbines.) | IEEE 2013 |
PE27 | DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions | Abstract—Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dccapacitor current control loop,where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced grid voltage conditions. A modular implementation method of the proposed control strategy is developed for the DFIG controller. Finally, experiments are presented to validate the theoretical analysis. (Index Terms—Control analysis, dc-capacitor current, doubly fed induction generator (DFIG), resonant controller, unbalanced grid voltage.) | IEEE 2013 |
PE28 | Design and Implementation of Energy Management System With Fuzzy Control for DC Microgrid Systems | Abstract—This paper presents the design and implementation of an energy management system (EMS) with fuzzy control for a dc microgrid system.Modeling, analysis, and control of distributed power sources and energy storage devices withMATLAB/Simulink are proposed, and the integrated monitoring EMS is implemented with LabVIEW. To improve the life cycle of the battery, fuzzy control manages the desired state of charge. The RS-485/ZigBee network has been designed to control the operating mode and to monitor the values of all subsystems in the dc microgrid system. (Index Terms—Energy management system (EMS), fuzzy control, microgrid.) | IEEE 2013 |
PE29 | Design Methodology for a Very High Frequency Resonant Boost Converter | Abstract—This paper introduces a designmethodology for a resonant boost converter topology that is suitable for operation at very high frequencies. The topology we examine features a low parts count and fast transient response, but suffers from higher device stresses compared to other topologies that use a larger number of passive components.Anumerical design procedure is developed for this topology that does not rely on time-domain simulation sweeps across parameters. This allows the optimal converter design to be found for a particular main semiconductor switch. If an integrated power process is used where the designer has control over layout of the semiconductor switch, the optimal combination of converter design and semiconductor layout can be found. To validate the proposed converter topology and design approach, a 75-MHz prototype converter is designed and experimentally demonstrated. The performance of the prototype closely matches that predicted by the design procedure, and the converter achieves good efficiency over a wide input voltage range. (Index Terms—DC-DC power converters, power transistors, RLC circuits, schottky diodes, tuned circutis.) | IEEE 2013 |
PE30 | Design Optimization of Transformerless Grid-Connected PV Inverters Including Reliability | Abstract—This paper presents a new methodology for optimal design of transformerless photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal switching frequency as well as the optimal values and types of the PV inverter components is calculated such that the PV inverter LCOE generated during the PV system lifetime period is minimized. The LCOE is also calculated considering the failure rates of the components, which affect the reliability performance and lifetime maintenance cost of the PV inverter. A design example is presented, demonstrating that compared to the nonoptimized PV inverter structures, the PV inverters designed using the proposed optimization methodology exhibit lower total manufacturing and lifetime maintenance cost and inject more energy into the electricgrid and by that minimizing LCOE. (Index Terms—DC–AC power conversion, failure analysis, optimization methods, photovoltaic (PV) power systems, reliability.) | IEEE 2013 |
PE31 | Design, Analysis, and Implementation of Solar Power Optimizer for DC Distribution System | Abstract—This paper proposes a high step-up solar power optimizer (SPO) that efficiently harvests maximum energy from a photovoltaic (PV) panel then outputs energy to a dc-microgrid. Its structure integrates coupled inductor and switched capacitor technologies to realize high step-up voltage gain. The leakage inductance energy of the coupled inductor can be recycled to reduce voltage stress and power losses. A low voltage rating and low-conduction resistance switch improves system efficiency by employing the incremental conductance method for the maximum power point tracking (MPPT) algorithm. Because of its high tracking accuracy, the method is widely used in the energy harvesting of PV systems. laboratory prototypes of the proposed SPO that have an input voltage range of 20 to 40 V and a maximum PV output power of 400 V/300 W are applied. The highest PV power conversion efficiency is 96.7%. The maximum MPPT accuracy is 99.9%, and the full load average MPPT accuracy is 97.8%. (Index Terms—High step-up voltage gain, maximu tracking (MPPT), solar power optimizer (SPO).) | IEEE 2013 |
PE32 | Development and Operational Control of Two-String Maximum Power Point Trackers in DC Distribution Systems | Abstract—This paper develops the operational control of two maximum power point trackers (MPPTs) for two-string photovoltaic (PV) panels in dc distribution systems. This dc distribution system is connected to ac grid via a bidirectional inverter. Two PV strings and two MPPTs are implemented in this system. The proposed MPPT topology consists of buck and boost converters to deal with wide output voltage range of PV panels. To accurately determine the input current of MPPTs, the PV-string configuration check is accomplished online. The perturbation and observation method are applied for maximum power point tracking. Moreover, the current balancing of two MPPT modules in parallel is achieved. In this paper, the system configuration and the operational principle of the proposed MPPT are first introduced. Afterward, the perturbation and observation method and the mode transition are demonstrated. Flowcharts of the online PV-string configuration check and current balancing are explained. The validity of configuration check and current balancing is verified via the experimental results. Maximum power tracking performance and power conversion efficiency are also obtained. (Index Terms—Current balancing, dc distribution system, maximum power point tracking, photovoltaic (PV), solar power.) | IEEE 2013 |
PE33 | Digital Plug-In Repetitive Controller for Single-Phase Bridgeless PFC Converters | Abstract—This paper investigates a plug-in repetitive control scheme for bridgeless power factor correction (PFC) converters to mitigate input current distortions under continuous conduction mode and discontinuous conduction mode operating conditions. From the PFC converter model and the fact that a type-II compensator is used, a design methodology to maximize the bandwidth of the feedback controller is suggested. After that, the error transfer function including the feedback controller is derived, and the stability of the repetitive control scheme is evaluated using the error transfer function. The implementation of the digital repetitive controller is also discussed. The simulation and experimental results show that the input current THD is significantly improved by using the proposed control scheme for a 1-kW single-phase bridgeless PFC converter prototype. (Index Terms—AC–DC converters, bridgeless power factor correction (PFC) converter, digital average current control, repetitive control.) | IEEE 2013 |
PE34 | Dual Transformerless Single-Stage Current Source Inverter With Energy Management Control Strategy | Abstract—Alternative energy sources have for some time attracted great interest in the area of static converter development. This fact is related in greater part to issues such as sustainability and detrimental effects on the natural environment, which all contribute to the viability of this type of energy source. In this context, power electronics performs important tasks making viable the connection of all these kind of clean power sources to the conventional grid and also to the load. From this perspective, a new challenge must be faced which is the development of energy management systems capable of providing intelligent planning and control of appliances in low- and high-power applications. That being so, this paper intends to contribute presenting a novel dual transformerless single-stage current source inverter fed by a proton exchange membrane fuel cell (PEMFC) and a photovoltaic (PV) array. High voltage gain and totally controlled output voltage can be achieved without using dedicated step-up dc–dc converters or transformers either. The main feature of this inverter structure is the intelligent power management technique which focuses on the extraction of maximum power from the PV array keeping the PEMFC as an energy storage system. Theoretical analysis is presented and corroborated by experimental results of a 400Wlaboratory prototype. (IndexTerms—Buck–boost, current source inverter (CSI), energy management, fuel cell (FC), inverters, photovoltaic (PV), singlestage, transformerless.) | IEEE 2013 |
PE35 | Electric Equivalent Model for Induction Electrodeless Fluorescent Lamps | Abstract—This paper presents an electric equivalent model applied to induction electrodeless fluorescent lamps. The model is based on passive components and takes into account the real and reactive lamp power. The presented model and its obtention methodology will be an important tool for ballast designers. One of the most important features of the proposed methodology is the concern regarding core losses and lamp reactive characteristics, because nowadays there are no electricmodels including these characteristics. In order to obtain and validate the electrodeless lamp model, a series–parallel resonant half-bridge inverter is used as ballast. Plasma and lamp windings are modeled as resistances and reactances depending on the lamp power. Simulations employing the proposed model are also presented, showing an excellent agreement with experimental results. (Index Terms—Electrodeless fluorescent lamps, equivalent model, high frequency.) | IEEE 2013 |
PE36 | Enhanced Control of a DFIG-Based Wind-Power Generation System With Series Grid-Side Converter Under Unbalanced Grid Voltage Conditions | Abstract—This paper presents an enhanced control method for a doubly fed induction generator (DFIG)-based wind-power generation system with series grid-side converter (SGSC) under unbalanced grid voltage conditions. The behaviors of the DFIG system with SGSC during network unbalance are described. By injecting a series control voltage generated from the SGSC to balance the stator voltage, the adverse effects of voltage unbalance upon the DFIG, such as stator and rotor current unbalances, electromagnetic torque, and power pulsations, can be removed, and then the conventional vector control strategy for the rotor-side converter remains in full force under unbalanced conditions. Meanwhile, three control targets for the parallel grid-side converter (PGSC) are identified, including eliminating the oscillations in the total active power or reactive power, or eliminating negative-sequence current injected to the grid. Furthermore, a precise current reference generation strategy for the PGSC has been proposed for the PGSC to further improve the operation performance of the whole system. Finally, the proposed coordinated control strategy for the DFIG system with SGSC has been validated by the simulation results of a 2-MW-DFIG-based wind turbine with SGSC and experimental results on a laboratory-scale experimental rig under small steady-state grid voltage unbalance. (Index Terms—Doubly fed induction generator (DFIG), enhanced control, grid voltage unbalance, series grid-side converter (SGSC), wind-power generation.) | IEEE 2013 |
PE37 | Generalized Multicell Switched-Inductor and Switched-Capacitor Z-Source Inverters | Abstract—Traditional voltage-source inverter is limited by its only voltage step-down operation, while current-source inverter is limited by its only current step-down mode. In order to add an extra boosting flexibility while keeping the number of active semiconductors unchanged, voltage-type and current-type Z-source inverters were earlier proposed. These new classes of inverters are generally more robust and less sensitive to electromagnetic noises. However, their boosting capabilities are somehow compromised by high component stresses and poorer spectral performances caused by low modulation ratios. Their boosting gains are, therefore, limited in practice. To overcome these shortcomings, the generalized switched-inductor and switched-capacitor Z-source inverters are proposed,whose extra boosting abilities and other advantages have already been verified in simulation and experiment. (Index Terms—Cascaded inverters, multicell inverters, switchedcapacitor (SC), switched-inductor (SL), Z-source inverters.) | IEEE 2013 |
PE38 | Grid Interfacing of Multimegawatt Photovoltaic Inverters | Abstract—This paper investigates the suitability of selective harmonic elimination (SHE) for low-loss multimegawatt gridconnected photovoltaic (PV) inverters. The proposed system is able to meet utilities regulations, IEEE and IEC standards. In an attempt to substantiate the potential superiority of SHE over carrier-based or space-vector pulsewidth modulation (PWM), this paper demonstrates that SHE may allow grid-connected PV inverters to be controlled using a switching frequency of less than 1 kHz, while the inverter is still able to provide necessary operation features such as independent control of active and reactive powers and operation control simplicity. For system validation, experimental results with SHE are compared to the case when the inverter is controlled using third-harmonic injection PWM, with a 2-kHz switching frequency. Furthermore, the paper proposes a new implementation technique for SHE that utilizes the third harmonics to spread the switching angles over 90◦ instead of being located in a narrow range as generated when using conventional techniques, along with increases in modulation index. The advantages of the proposed technique include simplicity in implementation and flexibility in PWM waveforms. Simulation and experimentation demonstrate agreement, which validates the practicability of the proposed system. (Index Terms—Grid-connected photovoltaic inverters, highpower medium-voltage inverters, pulsewidth modulations (PWMs), switching losses.) | IEEE 2013 |
PE39 | High Boost Ratio Hybrid Transformer DC–DC Converter for Photovoltaic Module Applications | Abstract—This paper presents a nonisolated, high boost ratio hybrid transformer dc–dc converter with applications for low-voltage renewable energy sources. The proposed converter utilizes a hybrid transformer to transfer the inductive and capacitive energy simultaneously, achieving a high boost ratio with a smaller sized magnetic component. As a result of incorporating the resonant operation mode into the traditional high boost ratio pulsewidth modulation converter, the turn-off loss of the switch is reduced, increasing the efficiency of the converter under all load conditions. The input current ripple and conduction losses are also reduced because of the hybrid linear-sinusoidal input current waveforms. The voltage stresses on the active switch and diodes are maintained at a low level and are independent of the changing input voltage over a wide range as a result of the resonant capacitor transferring energy to the output of the converter. The effectiveness of the proposed converter was experimentally verified using a 220-W prototype circuit. Utilizing an input voltage ranging from 20 to 45V and a load range of 30–220W, the experimental results show system of efficiencies greater than 96% with a peak efficiency of 97.4% at 35-V input, 160-W output. Due to the high system efficiency and the ability to operate with a wide variable input voltage, the proposed converter is an attractive design for alternative low dc voltage energy sources, such as solar photovoltaic modules and fuel cells. (Index Terms—California energy commission (CEC) efficiency, energy sources with low dc voltage, European union (EU) efficiency, high boost ratio dc–dc, high efficiency, hybrid transformer, photovoltaic (PV) module.) | IEEE 2013 |
PE40 | High Power Factor AC–DC LED Driver With Film Capacitors | Abstract—In this paper, a new method is proposed to eliminate electrolytic capacitors in a two-stage ac–dc light-emitting diode (LED) driver. DC-biased sinusoidal or square-wave LED drivingcurrent can help to reduce the power imbalance between ac input and dc output. In doing so, film capacitors can be adopted to improve LED driver’s lifetime. The relationship between the peakto- average ratio of the pulsating current in LEDs and the storage capacitance according to given storage capacitance is derived. Using the proposed “zero-low-level square-wave driving current” scheme, the storage capacitance in the LED driver can be reduced to 52.7% comparing with that in the driver using constant dc driving current. The input power factor is almost unity, which complies with lighting equipment standards such as IEC-1000-3-2 for Class C equipments. The voltage across the storage capacitors is analyzed and verified during the whole pulse width modulation dimming range. For the ease of dimming and implementation, a 50WLED driver with zero-low-level square-wave driving current is built and the experimental results are presented to verify the proposed methods. (Index Terms—Converters, dimming, LED driver, lighting, pulsating driving current.) | IEEE 2013 |
PE41 | High-Efficiency Asymmetrical Half-Bridge Converter Without Electrolytic Capacitor for Low-Output-Voltage AC–DC LED Drivers | Abstract—Due to their high reliability and luminous efficacy, high-brightness light-emitting diodes are being widely used in lighting applications, and therefore, their power supplies are required to have also high reliability and efficiency. A very common approach for achieving this in ac–dc applications is using a two-stage topology. The power factor corrector boost converter operating in the boundary conduction mode is a very common converter used as first stage. It is normally designed without electrolytic capacitors, improving reliability but also increasing the low-frequency ripple of the output voltage. The asymmetrical half-bridge (AHB) is a perfect option for the second stage as it has very high efficiency, it operates at constant switching frequency, and its output filter is small (i.e., it can be also easily implemented without electrolytic capacitors). Moreover, the AHB is an excellent candidate for selfdriven synchronous rectification (SD-SR) as its transformer does not have dead times. However, the standard configuration of the SD-SR must bemodified in this case in order to deal with the transformer voltage variations due to the input voltage ripple and, more important, due to the LED dimming state. This modification is presented in this paper. Another important issue regarding the AHB is that its closed-loop controller cannot be very fast and it cannot easily cancel the previously mentioned low-frequency ripple. In this paper, a feed-forward technique, specifically designed to overcome this problem, is also presented. The experimental results obtained with a 60-W topology show that efficiency of the AHB may be very high (94.5%), while the inherent control problems related to the AHB can be overcome by the proposed feed-forward technique. (Index Terms—AC–DC converter, asymmetrical half bridge, dc– dc converter, LED drivers, low-output voltage, self-driven synchronous rectification (SD-SR).) | IEEE 2013 |
PE42 | High-Efficiency Single-Input Multiple-Output DC–DC Converter | Abstract—The aim of this study is to develop a high-efficiency single-input multiple-output (SIMO) dc–dc converter. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage dc bus and middle-voltage output terminals. The high-voltage dc bus can take as the main power for a high-voltage dc load or the front terminal of a dc–ac inverter. Moreover, middle-voltage output terminals can supply powers for individual middle-voltage dc loads or for charging auxiliary power sources (e.g., battery modules). In this study, a coupled-inductorbased dc–dc converter scheme utilizes only one power switch with the properties of voltage clamping and soft switching, and the corresponding device specifications are adequately designed. As a result, the objectives of high-efficiency power conversion, high stepup ratio, and various output voltages with different levels can be obtained. Some experimental results via a kilowatt-level prototype are given to verify the effectiveness of the proposed SIMO dc–dc converter in practical applications. (Index Terms—Coupled inductor, high-efficiency power conversion, single-input multiple-output (SIMO) converter, soft switching, voltage clamping.) | IEEE 2013 |
PE43 | Hybrid-Frequency Modulation for PWM-Integrated Resonant Converters | Abstract—This paper presents a unique modulation method for extending the input range of pulse-width modulation (PWM)- integrated resonant converters, such as the isolated boost resonant converter, while maintaining high conversion efficiency. The technique includes primarily the hybridizing of constant-on, constantoff, and fixed-frequency control depending only on the required duty cycle. The modulation scheme reduces core loss and conduction loss dramatically by decreasing the applied volt-seconds at the transformer and improving the switching period utilization. With hybrid-frequency control, the circuit alsomaintains zero current switching for the output diodes, minimizes switching loss, and eliminates circulating energy at the transformer across the entire operating range. It also allows for a predictable voltage gain, dependent only on duty cycle and transformer turns ratio. A detailed loss analysis is provided and verified against a 180 W experimental prototype, with an input range of 12–48 V and a switching frequency range of 30–70 kHz. Implementation issues are also handled with a variety of solutions for realizing the modulation scheme. Experimental results show greater than 4% weighted efficiency improvement in the prototype using the proposed method. (Index Terms—DC–DC modulation, integrated boost resonant (IBR) converter) | IEEE 2013 |
PE44 | Improved Sensorless Operation of a CSI-Based Induction Motor Drive: Long Feeder Case | Abstract—Various applications, like in underground mines and oil and gas industries, require remote operation of vectorcontrolled medium-voltage variable speed drives via a long motor feeder. The use of voltage source inverters in such cases leads to motor overvoltage and harmonic quality problems. The current source inverter (CSI) is ideally matched to these applications because of its motor-friendly voltage output. Speed sensorless operation is mandatory due to the longmotor feeder. Although the model reference adaptive system (MRAS) is a powerful and proven speed estimation tool, its implementation in long motor feeder drives faces many challenges. Among them, and addressed in this paper, are inherent dc offset in its stator model, the need for actual motor voltage and current values, and oscillations in the estimated speed due to errors in the motor current measurement signals. In this paper, a sensorless CSI vector-controlled drive, suitable for long motor feeder applications, is studied. Improved speed estimation is achieved by proposing 1) a modified dc-offset eliminator for an MRAS speed estimation and 2) a compensation technique for motor current’s measurement errors. Intensive experimental results, for a low-voltage scaled model, along with simulations validate the effectiveness of the proposed technique. (Index Terms—Current source inverter, long feeder, medium voltage drives, speed sensor-less.) | IEEE 2013 |
PE45 | Improved Trans-Z-Source Inverter With Continuous Input Current and Boost Inversion Capability | Abstract—This paper deals with a new family of high boost voltage inverters that improve upon the conventional trans-Z-source and trans-quasi-Z-source inverters. The improved trans-Z-source inverter provides continuous input current and a higher boost voltage inversion capability. In addition, the improved inverter can suppress resonant current at startup, which might destroy the device. In comparison to the conventional trans-Z-source/-trans-quasi-Zsource inverters, for the same transformer turn ratio and input and output voltages, the improved inverter has a higher modulation index with reduced voltage stress on the dc link, lower current stress flow on the transformer windings and diode, and lower input current ripple. In order to produce the same input and output voltage with the same modulation index, the improved inverter uses a lower transformer turn ratio compared to the conventional inverters. Thus, the size and weight of the transformer in the improved inverter can be reduced. This paper presents the operating principles, analysis and simulation results, and compares them with those of the conventional trans-Z-source/-quasi-Z-source inverters. To verify the performance of the improved converter, a laboratory prototype was constructed based on a TMS320F2812 digital signal processor with 100 Vdc input and 115 Vrms output voltage. (Index Terms—Boost inversion ability, shoot-through state, trans-Z-source inverter, transformer, Z-source inverter.) | IEEE 2013 |
PE46 | Improved Voltage-Vector Sequences on Dead-Beat Predictive Direct Power Control of Reversible Three-Phase Grid-Connected Voltage-Source Converters | Abstract—This paper presents a dead-beat predictive direct power control (DPC) strategy and its improved voltage-vector sequences for reversible three-phase grid-connected voltage-source converters (VSCs). The instantaneous variation rates of active and reactive powers, by applying each converter voltage vector in 12 different sectors, are deduced and analyzed. Based on the power variation rates, it is found that the values of the predicted duration times for the two conventional active converter voltage vectors are less than zero when the grid-connected VSC operates as either a rectifier or an inverter. In order to solve this issue, two new alternative vector sequences are proposed and compared. Experimental results on a 1.5 kW reversible grid-connected VSC system are presented to validate the feasibility of the proposed voltage-vector sequences on the dead-beat predictive DPC strategy. (Index Terms—Dead-beat, direct power control (DPC), duration time, predictive, vector sequences, voltage-source converter (VSC).) | IEEE 2013 |
PE47 | Input Differential-Mode EMI of CRM Boost PFC Converter | Abstract—In this paper, the differential-mode (DM) electromagnetic interference (EMI) noise of a single-phase boost power factor correction converter operating in critical current mode was analyzed. The DM noise spectra are calculated based on the mathematicalmodel of EMI receiver and the required corner frequencies of DM filter are obtained. It can be seen that the minimum corner frequencies are determined by the maximum noises at 150 kHz. With the relation between the magnitude of the inductor current ripple and theDMnoise, the characteristics of noise at 150 kHz are obtained by analyzing the current ripple magnitude at 150 kHz; thus, the worst conditions which have the maximum noise value are figured out. Meanwhile, the maximum noises at 150 kHz for different input voltages are identical, so the DM filter can be designed based on one worst spectrum at one input voltage without testing the spectra in other conditions. (Index Terms—Boost converter, critical current mode (CRM), differential mode (DM), electromagnetic interference (EMI), power factor correction (PFC).) | IEEE 2013 |
PE48 | Integration and Operation of a Single-Phase Bidirectional Inverter With Two Buck/Boost MPPTs for DC-Distribution Applications | Abstract—This study is focused on integration and operation of a single-phase bidirectional inverter with two buck/boost maximum power point trackers (MPPTs) for dc-distribution applications. In a dc-distribution system, a bidirectional inverter is required to control the power flow between dc bus and ac grid, and to regulate the dc bus to a certain range of voltages.Adroop regulation mechanism according to the inverter inductor current levels to reduce capacitor size, balance power flow, and accommodate load variation is proposed. Since the photovoltaic (PV) array voltage can vary from 0 to 600 V, especially with thin-film PV panels, the MPPT topology is formed with buck and boost converters to operate at the dc-bus voltage around 380 V, reducing the voltage stress of its followed inverter. Additionally, the controller can online check the input configuration of the two MPPTs, equally distribute the PV-array output current to the twoMPPTs in parallel operation, and switch control laws to smooth out mode transition. A comparison between the conventional boostMPPT and the proposed buck/boostMPPT integrated with a PV inverter is also presented. Experimental results obtained froma 5-kW system have verified the discussion and feasibility. (Index Terms—Bidirectional inverter, buck/boost maximum power point trackers (MPPTs), dc-distribution applications.) | IEEE 2013 |
PE49 | Interleaved Boundary Conduction Mode (BCM) Buck Power Factor Correction (PFC) Converter | Abstract—An interleaved boundary conduction mode powerfactor- correction buck converter that maintains high efficiency across entire load and line range is proposed. The adaptive master– slave interleaving method maintains stable 180◦ out-of-phase operation during any transient. By interleaving two parallel-connected buck converters, the input current ripple is halved while the ripple frequency is doubled, which leads to a smaller differential mode line filter. The line current harmonic distortion is analyzed to examine the allowable output voltage range while meeting harmonic regulations. The operation and performance of the proposed circuit is verified on a 300 W, universal line experimental prototype with 80 V output. The measured efficiencies remain above 96% down to 20% of full load across the entire universal line range. Even at 10% of full-load condition, the efficiency remains above 94%. The input current harmonics also meet the IEC61000-3-2 (class D) standard. (Index Terms—Boundary conduction mode (BCM), buck converter, interleaving, power factor correction (PFC).) | IEEE 2013 |
PE50 | Light-Load Efficiency Improvement in Buck-Derived Single-Stage Single-Switch PFC Converters | Abstract—Single-stage single-switch ac/dc converters with power factor correction (PFC) generally have higher power losses under a light-load condition, as compared to that of the two-stage approach, due to the sharing of a common power transistor such that the PFC stage cannot be switched OFF separately to save power losses. This letter addresses this problem by using a buck topology for the PFC stage of the single-stage single-switch converters as it can be completely turned OFF by operating the converter only near the zero crossing of the input voltage, due to the presence of the dead angle of input current. Hence, the switching and conduction losses to the transistor and diodes, and passive devices are reduced. Also, further improvement is made by finding the best combination of dc-bus capacitor charging time and discharging time to achieve the lowest power loss. A recently proposed converter topology which combines a buck PFC cell with a buck–boost dc/dc cell is used as an example. Experimental results are reported and confirmed that the proposed light-load power loss reduction scheme on the converter can improve power stage efficiency by up to 7% at 1 W of output power as compared to that without the proposed scheme. (Index Terms—Light-load efficiency, power consumption, Power factor correction, single-stage.) | IEEE 2013 |
PE51 | Light-to-Light: PV-Fed LED Lighting Systems | Abstract—This paper discusses the principle of operation, dynamic modeling, and control design for light-to-light (LtL) systems, whose aim is to directly convert the sun irradiation into artificial light. The system discussed in this paper is composed by a photovoltaic (PV) panel, an LED array, a dc–dc converter dedicated to the maximum power point tracking of the PV panel and a dc–dc converter dedicated to drive the LEDs array. A system controller is also included, whose goal is to ensure the matching between the maximum available PV power and the LED power by means of a low-frequency LEDs dimming. An experimental design example is discussed to illustrate the functionalities of the LtL system. (Index Terms—LED lighting, maximum power point tracking, PV systems.) | IEEE 2013 |
PE52 | Mitigation of Lower Order Harmonics in a Grid-Connected Single-Phase PV Inverter | Abstract—In this paper, a simple single-phase grid-connected photovoltaic (PV) inverter topology consisting of a boost section, a low-voltage single-phase inverter with an inductive filter, and a step-up transformer interfacing the grid is considered. Ideally, this topology will not inject any lower order harmonics into the grid due to high-frequency pulse width modulation operation. However, the nonideal factors in the system such as core saturation-induced distorted magnetizing current of the transformer and the dead time of the inverter, etc., contribute to a significant amount of lower order harmonics in the grid current. A novel design of inverter current control that mitigates lower order harmonics is presented in this paper. An adaptive harmonic compensation technique and its design are proposed for the lower order harmonic compensation. In addition, a proportional-resonant-integral (PRI) controller and its design are also proposed. This controller eliminates the dc component in the control system, which introduces even harmonics in the grid current in the topology considered.The dynamics of the system due to the interaction between the PRI controller and the adaptive compensation scheme is also analyzed. The complete design has been validated with experimental results and good agreement with theoretical analysis of the overall system is observed. (Index Terms—Adaptive filters, harmonic distortion, inverters, solar energy.) | IEEE 2013 |
PE53 | Modeling and Simulation of All-Electric Ships With Low-Voltage DC Hybrid Power Systems | Abstract—DChybrid power systems are of interest for future low emission, fuel-efficient vessels. In spite of the advantages they offer onboard a ship, they result in a complex, interconnected system, which requires effective analysis tools to enable a full realization of the advantages. Modeling and simulation are essential tools to facilitate design, analysis, and optimization of the system. This paper reviews modeling of hybrid electric ship components including mechanical and electrical elements. Power electronic converters are modeled by nonlinear averaging methods to suit system-level studies. A unified model for bidirectional converters is proposed to avoid transitions between two separate models. A simulation platform using the derived models is developed for the system-level analysis of hybrid electric ships. Simulation results of power sharing among two diesel generators, a fuel cell module, and an energy storage system are presented for three modes of operation. (Index Terms—DC distribution systems, modeling, simulation, transportation.) | IEEE 2013 |
PE54 | Multilevel DC-Link Inverter and Control Algorithm to Overcome the PV Partial Shading | Abstract—This letter presents for the first time the application of multilevel dc-link inverter to overcome the problem of partial shading of individual photovoltaic (PV) sources which are connected in series. The “PV permutation algorithm,” as a new method, is developed for the control of the inverter so as to extract the maximum power form each PV source under partial shading and to deliver all that power to the load. The algorithm is based on combination of the direct pulsewidth modulation, the sequential permutation PV sources, and the output generation to control the multilevel dc-link inverter. The algorithm is applied successfully to a seven-level inverter with separate maximum power point tracking algorithm for each PV source and under nonuniform irradiance (partial shading). Digital processing unit F28335 eZdsp is used to control the PV system in the real-time mode, and MATLAB–Simulink real-time data exchange is employed to display the extracted power and to control the system parameters via a designed graphical user interface window. The implementation and experimental results are presented. (Index Terms—Maximum power point tracking (MPPT), multilevel inverter, photovoltaic partial shading, real-time data exchange (RTDX).) | IEEE 2013 |
PE55 | Mutual Impedance of Small Ring-Type Coils for Multiwinding Induction Heating Appliances | Abstract—This paper proposes amodel of the mutual impedance between ring-type coils used in domestic induction hobs. Recent developments in these appliances have focused on flexible cooking surfaces, including adjustable-size or total-active surfaces. Flexible cooking surfaces are implemented by means of several small ring-type closely arranged coils, each one supplied by a resonant inverter. The basic winding is a ring-type circular small coil, whose self-impedance has been reported previously. In this paper, the coupling between coils in terms of impedance is derived. The coils are modeled as axisymmetric current density distributions with parallel revolution axes. The mutual impedance between the coils is obtained considering two media representing the load and the ferrite, respectively. Experimental measurements have been performed to validate the results. (Index Terms—Frequency-dependent impedance, home appliances, impedance matrix, impedance measurements, induction heating, inductors, mutual coupling, mutual impedance.) | IEEE 2013 |
PE56 | Nonlinear Behavior and Instability in a Three-Phase Boost Rectifier Connected to a Nonideal Power Grid With an Interacting Load | Abstract—Three-phase voltage source converters (VSCs) are commonly used to convert ac power from a three-phase grid to a regulated dc voltage with unity input power factor. The control of the VSC is normally achieved by an outer voltage feedback loop and a sinusoidal pulsewidth-modulated inner current loop. However, the nonideal power grid and the presence of other interacting loads give rise to nonlinear operation and drive the VSC to enter an irreversible instability region. In this paper, an irreversible bifurcation phenomenon in a three-phase VSC connected to a power grid with an interacting load is reported. The converter can also be regarded as exhibiting a catastrophic bifurcation in which the input current expands to impose undesirable component stress. A large-signal analysis is adopted to identify the physical origin of the phenomenon and to locate the boundary of the instability. Experimental results on a 4-kVA ac/dc converter prototype provide verification of the instability phenomenon. (Index Terms—Bifurcation, instability, power grid, three-phase voltage source converter (VSC).) | IEEE 2013 |
PE57 | Novel Energy Conversion System Based on a Multimode Single-Leg Power Converter | Abstract—This paper presents a novel power conversion topology for systems, which include a boost and bidirectional converters to control the power flows between sources, batteries, and ultracapacitors. The proposed system (multimode single-leg power converter) substitutes the boost converter and bidirectional converter with a multifunctional bidirectional converter and has cost effectiveness and fault tolerance, preserving the same energy conversion functionalities of the conventional energy conversion system. To verify the performance of the proposed system, its operations are categorized and explained to four different modes. Then, each mode of the proposed system is simulated and implemented experimentally using a prototype test bed. The results present that the proposed conversion system is feasible and applicable for a wide range of applications including alternative/renewable power systems and electric vehicles (EVs).(Index Terms—Bidirectional converter, energy conversion, hybrid vehicles, renewable energy.) | IEEE 2013 |
PE58 | Origin of Cross-Coupling Effects in Distributed DC–DC Converters in Photovoltaic Applications | Abstract—Long strings of photovoltaic (PV) modules are found to be vulnerable to shading effects, causing significant reduction in the system power output. To overcome this, distributed maximum power point-tracking (DMPPT) schemes have been proposed, in which individual dc–dc converters are connected to each PV module to enable module-wise maximum power extraction. There are twomain concepts to implementDMMPTsystems: series and parallel configuration, describing the connection of the output terminals of the converters. Both systems are studied intensively, with innovative solutions to encountered operational challenges and novel control methods. However, a comprehensive dynamic model for neither system has been presented so far. This paper fills the gap by presenting small-signal models for both configurations, explaining the observed operational peculiarities. The analytical claims are verified with a practical system comprising two maximum power point-tracking buck–boost converters. (Index Terms—Cascaded converters, dc–dc power conversion, photovoltaic (PV) power systems.) | IEEE 2013 |
PE59 | Perturbation On-Time (POT) Technique in Power Factor Correction (PFC) Controller for Low Total Harmonic Distortion and High Power Factor | Abstract—The proposed perturbation on-time technique suppresses total harmonic distortion (THD) and, thus, improves the power factor in the power factor correction (PFC) controller. Besides, the adaptive control of the minimum off time by the proposed inhibit time control can improve efficiency even at lowac input voltage. Therefore, highly integrated PFC converter fabricated in the TSMC 800-V ultrahigh voltage process can achieve low THD of 6%, high PF of 99%, and high efficiency of 95% at the output power of 90W. (Index Terms—Inhibit time (IT) control, nonnegative-voltage zero current detector (NNV-ZCD), perturbation on time (POT), power factor correction (PFC), ultrahigh voltage (UHV).) | IEEE 2013 |
PE60 | Precise Accelerated Torque Control for Small Inductance Brushless DC Motor | Abstract—In this paper, precise accelerated torque control for a small inductance brushless dc motor (BLDCM) is achieved by electromagnetic torque control and disturbance torque suppression. First, the electromagnetic torque ripple is reduced in commutation and conduction regions. In the former region, the ripple is suppressed by overlapping commutation control and optimizing the duty ratio of the active controller. In the latter region, the unbalance ripple caused by the unbalanced three phase windings is reduced by the proposed asymmetry compensation function, and the disturbance ripple created by the back electromotive force (EMF) is compensated by feedforward control. Second, the disturbance torque has been observed and compensated through the improved disturbance torque controller whose compensation coefficient is obtained by line-to-line back EMF coefficient estimation. And, both the disturbance observation and speed measurement are all synchronized with the encoder pulse alteration. Experimental results are presented to demonstrate the validity and effectiveness of the proposed accelerated torque control scheme. (Index Terms—Accelerated torque, brushless dc motor (BLDCM), disturbance suppression, electromagnetic torque, small inductance, torque ripple.) | IEEE 2013 |
PE61 | Problems Incurred in a Vector-Controlled Single-Phase Induction Motor, and a Proposal for a Vector-Controlled Two-Phase Induction Motor as a Replacement | Abstract—This paper presents several of the problems encountered with vector-controlled single-phase induction motor (SPIM), and discusses about the complex implementation of a vector controlled SPIM drive. The vector-controlled symmetrical two-phase induction motor (TPIM) is presented as a viable replacement for the vector-controlled SPIM. The implementation of the proposed vector-controlled TPIM is simple compared to the vectorcontrolled SPIM. All the TPIM parameters can be calculated simply and precisely. The proposed strategy for TPIM is derived from the indirect vector control strategy used for three-phase ac machines. Several differences between the vector control strategies for the TPIM and for three-phase ac motor are discussed. The validity of the proposed vector-controlled TPIM was verified by simulations and experiments. (Index Terms—Vector-controlled single-phase induction motor (SPIM), vector-controlled two-phase induction motor (TPIM), unsymmetrical motor.) | IEEE 2013 |
PE62 | Reconfigurable Solar Converter: A Single-Stage Power Conversion PV-Battery System | Abstract—This paper introduces a new converter called reconfigurable solar converter (RSC) for photovoltaic (PV)-battery application, particularly utility-scale PV-battery application. The main concept of the new converter is to use a single-stage threephase grid-tie solar PV converter to perform dc/ac and dc/dc operations. This converter solution is appealing for PV-battery application, because itminimizes the number of conversion stages, thereby improving efficiency and reducing cost, weight, and volume. In this paper, a combination of analysis and experimental tests is used to demonstrate the attractive performance characteristics of the proposed RSC. (Index Terms—Converter, energy storage, photovoltaic (PV), solar.) | IEEE 2013 |
PE63 | Series Asymmetrical Half-Bridge Converters With Voltage Autobalance for High Input-Voltage Applications | Abstract—In this paper, an isolated series asymmetrical halfbridge converter (SA-HBC) is proposed to satisfy the high power and high input-voltage requirements. In the proposed converter, two half-bridge modules with series configuration are adopted in the primary side to reduce the switch voltage stress to half of the input voltage.Moreover, the series half-bridge cells share the same transformer and leakage inductance, which simplifies the circuit structure. Zero-voltage-switching transition is achieved for all the active switches by employing the asymmetrical control scheme to reduce the switching losses. Furthermore, the voltages of the input capacitors are automatically balanced without any additional components or complex control methods. In addition, a family of dc–dc converters with series half-bridge structure is explored to give a universal discussion and extensive applications of the proposed contributions for the high input-voltage systems. Finally, a 500–600-V input 48-V output 1-kW prototype operating with 100 kHz switching frequency is built and tested to demonstrate the effectiveness of the proposed SA-HBC converter. The efficiency of 95% at full load is realized. (Index Terms—High voltage applications and voltage autobalance ability, series asymmetrical half-bridge converter (SA-HBC).) | IEEE 2013 |
PE64 | Soft-Switching DC/DC Converter With a Full ZVS Range and Reduced Output Filter for High-Voltage Applications | Abstract—Anew soft-switching dc/dc converter, which can solve the drawbacks of existing phase-shifted full-bridge converters such as narrow zero-voltage-switching (ZVS) range, large circulating current, large duty-cycle loss, and a large output filter in highvoltage applications, is proposed in this paper. The proposed converter is composed of two symmetric half-bridge inverters that are placed in parallel on the primary side and are driven in a phase-shifting manner to regulate the output voltage. At the rectifier stage, two full-bridge rectifiers sharing two low-current-rating diodes are employed. This structure allows the proposed converter to have the advantages of a full ZVS range, no problems related to duty-cycle loss, no circulating current, and a significantly reduced output filter. In this paper, the circuit configuration, operation principle, and relevant analysis results of the proposed converters are presented. Experimental results on a prototype converter realized with the specification of 80-in plasma display panel sustain power module (320–385 Vdc input, 205 Vdc /5 A output) validate the theoretical analysis. (Index Terms—No circulating current, no duty-cycle loss, phaseshift, zero-voltage switching (ZVS).) | IEEE 2013 |
PE65 | Space-Vector-Modulated Three-Level Inverters With a Single Z-Source Network | Abstract—The Z-source inverter is a relatively recent converter topology that exhibits both voltage-buck and voltage-boost capability. The Z-source concept can be applied to all dc-to-ac, acto- dc, ac-to-ac, and dc-to-dc power conversion whether two-level or multilevel. However, multilevel converters offer many benefits for higher power applications. Previous publications have shown the control of a Z-source neutral point clamped inverter using the carrier-based modulation technique. This paper presents the control of a Z-source neutral point clamped inverter using the space vector modulation technique. This gives a number of benefits, both in terms of implementation and harmonic performance. The adopted approach enables the operation of the Z-source arrangement to be optimized and implemented digitally without introducing any extra commutations. The proposed techniques are demonstrated both in simulation and through experimental results from a prototype converter. (IndexTerms—Buck–boost, neutral point clamped inverter, space vector modulation (SVM), Z-source inverter.) | IEEE 2013 |
PE66 | Synchronous-Reference-Frame-Based Control of Switched Boost Inverter for Standalone DC Nanogrid Applications | Abstract—Switched boost inverter (SBI) is a single-stage power converter derived from Inverse Watkins Johnson topology. Unlike the traditional buck-type voltage source inverter (VSI), the SBI can produce an ac output voltage that is either greater or less than the available dc input voltage. Also, the SBI exhibits better electromagnetic interference noise immunity when compared to the VSI, which enables compact design of the power converter. Another advantage of SBI is that it can supply both dc and ac loads simultaneously from a single dc input. These features make the SBI suitable for dc nanogrid applications. In this paper, the SBI is proposed as a power electronic interface in dc nanogrid. The structure and advantages of the proposed SBI-based nanogrid are discussed in detail. This paper also presents a dq synchronousreference- frame-based controller for SBI, which regulates both dc and ac bus voltages of the nanogrid to their respective reference values under steady state as well as under dynamic load variation in the nanogrid. The control system of SBI has been experimentally validated using a 0.5-kW laboratory prototype of the SBI supplying both dc and ac loads simultaneously, and the relevant experimental results are given in this paper. The low cross regulation and the dynamic performance of the control system have also been verified experimentally for a 20% step change in either dc or ac load of SBI. These experimental results confirm the suitability of the SBI and its closed-loop control strategy for dc nanogrid applications. (Index Terms—DC nanogrid, switched boost inverter (SBI), synchronous reference frame (SRF) control.) | IEEE 2013 |
PE67 | Synthesizable Integrated Circuit and System Design for Solar Chargers | Abstract—In this paper, an automatic design tool for a solar energy harvesting IC and system is developed with visual basic software, and the synthesis tool employed in this approach can be used to shorten the design time to market. In addition, a smart meter system is developed to measure the solar energy harvesting system’s information with an online system. Users can thus get the proposed system’s information at any time and from anywhere. Finally, good agreement has been found between the analytic and experimental results. (Index Terms—Digital-to-analog converter (DAC), energy harvesting, pulsewidth modulation (PWM).) | IEEE 2013 |
PE68 | The TAIPEI Rectifier—A New Three-Phase Two-Switch ZVS PFC DCM Boost Rectifier | Abstract—A new, three-phase, two-switch, power-factorcorrection (PFC) rectifier that can achieve less than 5% inputcurrent total harmonic distortion (THD) and features zero-voltage switching (ZVS) of all the switches over the entire input-voltage and load ranges is introduced. The proposed rectifier also offers automatic voltage balancing across the two output capacitors connected in series,whichmakes it possible to use downstreamconverters designed with lower voltage-rated component that offer better performance and are less expensive than their high-voltage-rated counterparts. In addition, the proposed rectifier also exhibits low common-mode EMI noise. The performance of the proposed rectifier was evaluated on a 2.8-kW prototype with a 780-V output that was designed to operate in 340–520-VL-L,RMS input-voltage range. (Index Terms—Boost converter, discontinuous conduction mode, power factor correction, three phase, voltage balancing, zerovoltage switching.) | IEEE 2013 |
PE69 | Triple Loop Modulation (TLM) for High Reliability and Efficiency in a Power Factor Correction (PFC) System | Abstract—The proposed triple loop modulation (TLM) can ensure reliability of the power factor correction (PFC) system due to the improvement of transient response. In conventional design, low bandwidth of less than 20Hz that rejects ac source of 60/120 Hz coupling deteriorates system reliability in case of output load variation. Contrarily, the proposedTLMcan automatically adjust bandwidth to rapidly increase or decrease inductor current to shorten transient response time. Besides, in the steady state, system stability can be guaranteed by low-frequency compensation pole without being affected by the TLM. The test circuit fabricated in a VIS 500 V UHV laterally diffused metal–oxide–semiconductor transistor process demonstrates that the highly integrated PFC controller with the proposed TLM has high power factor of 99%, high efficiency of 95%, and high power driving capability of about 90 W. The improvement in transient response is twofold faster than in conventional PFC design with output load variation from 90 to 20W and vice versa. (Index Terms—Fast transient response, power factor correction (PFC), triple loop modulation (TLM).) | IEEE 2013 |
PE70 | Unterminated Small-Signal Behavioral Model of DC–DC Converters | Abstract—The “black-box” modeling of dc–dc converters has always been an attractive topic widely used in engineering practice. However, in order to obtain unterminated model of dc–dc converter, the one had to be removed from the original environment and connected to the high-bandwidth voltage source and current sink for easier decoupling of the source and the load dynamics. This paper addresses an online dc–dc converter characterization procedurewhere converter under test can remainworking in the original environment, at the particular operating point, and be connected to any type of the source and the load while the terminated frequency response characteristics are obtained. The source and the load dynamics can then be decoupled from the measured frequency responses using here proposed linear transformation matrix. The verification and validation of the proposed technique will be both presented in this paper. (Index Terms—Behavioral model, dc power systems, decoupling, electronic power converters, un-terminated transfer functions.) | IEEE 2013 |
PE71 | Γ-Z-Source Inverters | Abstract—Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage in addition to their usual voltagebuck behavior. Comparing them with other topologies, the proposed inverters use lesser components and a coupled transformer for producing the high-gain and modulation ratio simultaneously. The obtained gain can be tuned by varying the turns ratio γΓZ of the transformer within the narrow range of 1 < γΓZ ≤ 2. This leads to lesser winding turns at high gain, as compared to other related topologies. Experimental testing has already proven the validity of the proposed inverters. (Index Terms—Embedded-Z-source, quasi-Z-source, T-source, trans-Z-source, Z-source, Γ-Z-source inverters.) | IEEE 2013 |