Zero Voltage Soft Switching Research Articles

An efficient soft switching synchronous buck converter for battery charging application in hybrid electric vehicle architecture

SummaryThis paper proposes a novel topology based on a zero voltage soft switching (ZVS) synchronous buck DC‐DC converter using an auxiliary unidirectional cell comprising a diode, a switch, and an inductor. This unidirectional cell aids in achieving the soft‐switching condition for the synchronous switches, thereby abating switching losses and enhancing the system efficiency. Furthermore, the presence of the unidirectional cell results in no additional current or voltage stress on the switches. This topology is well suited to hybrid electric vehicle (HEV) architecture. Detailed analysis and operation of the proposed topology are discussed. The results of the proposed topology are analyzed using MATLAB/Simulink software and validated experimentally.

A Voltage Spike Suppression Strategy Based on De-Re-Coupling Idea for the Three-Phase High-Frequency Isolated Matrix-Type Inverter

In order to solve the problem of high voltage spikes on the secondary side of the high-frequency transformer when the three-phase high-frequency isolated matrix inverter (HFIMI) operates under the conventional modulation strategies, a new modulation strategy is proposed without introducing an auxiliary circuit. In the proposed scheme, the H-bridge inverter adopts phase-shift control. The matrix converter (MC) adopts the voltage-type de- and recoupling idea, and the decoupled positive and negative group inverters are, respectively, applied with a modified Space vector pulse width modulation (SVPWM) strategy to operate synchronously with the H-bridge inverter. When the H-bridge inverter is in dead-zone mode, the switching tubes of MC are all turned <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> to provide continuous flow paths for leakage inductance and output filter inductance current and suppress high voltage spikes. The operating mode of the three-phase HFIMI under the proposed modulation strategy is analyzed in detail, the realization conditions for soft switching are designed, and the soft-switching ranges are also discussed. The feasibility and validity of the voltage spike suppression strategy are verified by building a 3-kW principle prototype. The experimental results show that the voltage spikes are effectively suppressed, all switches achieve zero-voltage soft-switching, and the peak efficiency of the three-phase HFIMI can reach 95.2%.

Efficient single-phase full-bridge soft-switching inverter

A MOSFET is often applied as the switch in medium and small power single-phase full-bridge inverters. In order to achieve efficient operation at a high switching frequency, a new efficient inverter is presented in this paper. In addition, two sets of identical auxiliary units are arranged on the two bridge arms. When the main switches need to be turned on in each switching period, the voltage across the resonant capacitor can become zero. Thus, the main switching device can achieve zero-voltage turn-on, which can eliminate the capacitive turn-on loss existing in the MOSFET and help with the efficient operation of the inverter. The working process of the auxiliary unit and the design rules of the parameters are analyzed. Experimental results indicate that the main switching device can work in the state of zero-voltage soft-switching, and that the rated efficiency in the inverter is equal to 98.9%. This is more than that of similar inverters. This topology is significant for studies on efficient single-phase full-bridge inverters with medium and small power.

Research on a Novel High-Efficiency Three-Phase Resonant Pole Soft-Switching Inverter

A high-efficiency three-phase resonant inverter is presented to optimize the performance of the inverter. When the auxiliary resonant circuit on each phase bridge arm works in the commutation process of the inverter, the voltage across resonant capacitors in parallel with main switches will form zero state periodically. In this case, main switches can achieve zero-voltage soft-switching. Meanwhile, auxiliary switches can achieve zero-current turn on and zero-voltage turn off during the operation of the auxiliary resonant circuit. Soft-switching can reduce switching loss and make the inverter work efficiently. The novelty of the inverter mainly reflects in the simple structure of the auxiliary circuit and the simple control method of auxiliary switches. This article analyzes the working mode of the circuit and the realization condition of soft-switching. Meanwhile, it discusses theoretical calculation of the power loss of the auxiliary circuit. The experimental results on the 3-kW prototype show that switching devices work in the soft-switching state. The efficiency of the prototype under the rated output power reaches 98.7%, which is higher than that of the same type of other soft-switching inverter. Therefore, the topology is valuable for the research and development of the high-performance three-phase inverter.

An efficient resonant DC link inverter

ABSTRACT An efficient three-phase resonant DC link inverter is put forward to optimise the efficiency. The assisted circuit is added on the DC link. When the main switches need to be operated, the assisted circuit has been in resonance state in advance. The voltage across DC link changes to zero, so that the main switches can act in the mode of zero-voltage soft-switching. Besides, the auxiliary switch can also act in the mode of soft-switching. Through control of the interval time of the action of the auxiliary switches, the zero-state duration of the DC link voltage can be adjusted, so that various flexible pulse width modulation strategies can be applied in the inverter. The workflow of the assisted circuit and the implementation conditions of soft-switching are illustrated at length. The experimental results indicate the main switches and the auxiliary switches can act in the mode of soft-switching. The efficiency at 4.5 kW is equal to 98.5%, which is superior to that of other similar inverters. Hence, the topology can provide reference for the design of efficient inverters.

Novel Soft-Switching Integrated Boost DC-DC Converter for PV Power System

This paper presents a novel soft-switching boost DC-DC converter, which uses an edge-resonant switch capacitor based on the pulse width modulation PWM technique. These converters have high gain voltage due to coupled inductors, which work as a transformer, while the boost converter works as a resonant inductor. Upon turning on, the studied soft switching circuit works at zero-current soft switching (ZCS), and upon turning off, it works at zero-voltage soft switching (ZVS) while using active semiconductor switches. High efficiency and low losses are obtained while using soft switching and auxiliary edge resonance to get a high step-up voltage ratio. A prototype model is implemented in the Power Electronics Laboratory, Assiut University, Egypt. Seventy-two-panel PV modules of 250 W each were used to simulate and execute the setup to examine the proposed boost converter.

A new soft switching PV module-integrated boost DC-DC converter

This paper introduces a new non-isolated soft switching boost PWM DC-DC converter utilising a switched capacitor edge-resonant cell. The proposed converters can readily fulfil a higher voltage gain due to coupled-inductor which render as a transformer to magnify the voltage gain. At the same time, the boost inductor serves as a resonant inductor. The studied soft switching circuit can achieve a zero-current soft-switching (ZCS) at turning-on and zero-voltage soft-switching (ZVS) at turning-off operations in the used active semiconductor switches. Those beneficial features enable a wider soft-switching range of operation with a higher step-up voltage ratio due to the auxiliary edge-resonance cell, which results in a higher efficiency and low losses. In order to demonstrate the effectiveness of the novel type boost converter, a small laboratory prototype is implemented by simulation and experimental setup using a standard 250-W, 72-cell PV module. Then, the operation performance of the implemented soft switching power converter is examined followed by the design guidelines of the proposed power converter and the results analysis.

Analysis, Design, and Implementation of DC–DC IBBC-DAHB Converter With Voltage Matching to Improve Efficiency

The interleaved bidirectional buck–boost converter dual active half-bridge (IBBC-DAHB) dc–dc converter consists of two converters IBBC and DAHB and a coupled inductor. The IBBC-DAHB converter has significant features such as low ripple current at the low-voltage side, low current stress on the input inductors, voltage stress across the switches less than the high-voltage side, high voltage gain, and zero-voltage soft switching. The converter offers high efficiency using phase-shift modulation when it operates at a nominal design operating point. However, the efficiency decreases due to high circulating current, high current stress, and limited soft-switching range when the source and load voltages deviate from their nominal values. This paper employs both duty cycle and phase-shift modulation methods to improve the above mentioned shortcomings using voltage matching for the DAHB converter. The proposed converter is analyzed and a 500-W experimental prototype with 40–60 V input voltage and 400 V output voltage under 100 kHz switching frequency is implemented to verify the theoretical results. The maximum efficiency of 97.15% is achieved at 60 V and 400 W. A flat efficiency characteristic for the converter is derived by the proposed control method, where the efficiency at 20% of nominal load is 91% and much higher than the phase-shift control, which is 70.8%.

Highly Efficient Secondary-Resonant Active Clamp Flyback Converter

Both high switching frequency and high efficiency are critical in reducing power adapter size. The active clamp flyback (ACF) topology allows zero voltage soft switching (ZVS) under all line and load conditions, eliminates leakage inductance and snubber losses, and enables high frequency and high power density power conversion. Traditional ACF ZVS operation relies on the resonance between leakage inductance and a small primary-side clamping capacitor, which leads to increased rms current and high conduction loss. This also causes oscillatory output rectifier current and impedes the implementation of synchronous rectification. This paper proposes a secondary-side resonance scheme to shape the primary current waveform in a way that significantly improves synchronous rectifier operation and reduces primary rms current. The concept is verified with a ${\mathbf{25}}\hbox{--}{\text{W/in}}^{3}$ high-density 45-W adapter prototype using a monolithic gallium nitride power IC. Over 93% full-load efficiency was demonstrated at the worst case 90-V ac input and maximum full-load efficiency was 94.5%.

Comparative Analysis and Optimization of Power Loss Based on the Isolated Series/Multi Resonant Three-Port Bidirectional DC-DC Converter

Based on the loss distribution and efficiency analysis, a comparative study between a series resonant three-port bidirectional DC-DC converter (SR-TBC) and a multi-resonant three-port bi-directional DC-DC converter (MR-TBC) is reported here. By using the Fourier equivalent analysis method in hand, the resonant current, switching current expressions, zero voltage soft switching (ZVS) conditions of MR-TBC and SR-TBC are deduced. Besides, in consideration of efficiency and soft switching aspects, the loss models of main power components and resonant elements are integrated and optimized for both topologies. Their loss distributions are established, and the different effects derived from the adoption of SiC MOSFET and Si MOSFET on the converter efficiency are discussed. Finally, to verify the theoretical analyses, comparative experiments under diverse load states are conducted based on the prototypes of the MR-TBC and SR-TBC. The obtained results demonstrate that the MR-TBC successfully broadens the ZVS range and thus achieves higher efficiency along the entire load range.

ZVS Phase-Shift PWM-Controlled Single-Stage Boost Full-Bridge AC–AC Converter for High-Frequency Induction Heating Applications

This paper presents a new single-stage utility frequency ac–high-frequency ac resonant power converter for high-frequency induction heating applications. The newly proposed ac–ac converter features a boost converter and a full-bridge resonant inverter integrated circuit with a source voltage sensorless control system. The experimental results of a 3.0 kW–40 kHz prototype are demonstrated on zero-voltage soft switching and steady-state characteristics, then, the validity of the proposed ac–ac converter is revealed from a practical viewpoint.

A high-efficiency DC-DC converter with LC resonant in the load-side of HFT and voltage doubler for solar PV systems

This paper presents the implementation of a prototype phase-shift soft-switching full-bridge PWM DC-DC power converter isolated by a high-frequency transformer (HFT). This circuit topology is based on a new concept of series resonant principle in the secondary side. The step-up HFT and the voltage doubler rectifier make this circuit suitable for low-voltage renewable sources such as fuel cell or PV applications. Meanwhile, all semiconductor switches can achieve zero-voltage soft-switching (ZVS) with the assistance of transformer leakage inductances and lossless capacitive snubbers. The new contribution of this work is that the passive semiconductor switches (diodes) on the secondary side can also perform ZVS and zero-current switching (ZCS) transitions with the assistance of voltage doubler capacitance. The theory of operation and the experimental setup of the proposed circuit with a rated output of 5 kW are presented and discussed. A comparison between simulation and experimental results is explored and illustrated.

A high-efficiency DC-DC converter with LC resonant in the load-side of HFT and voltage doubler for solar PV systems

This paper presents the implementation of a prototype phase-shift soft-switching full-bridge PWM DC-DC power converter isolated by a high-frequency transformer (HFT). This circuit topology is based on a new concept of series resonant principle in the secondary side. The step-up HFT and the voltage doubler rectifier make this circuit suitable for low-voltage renewable sources such as fuel cell or PV applications. Meanwhile, all semiconductor switches can achieve zero-voltage soft-switching (ZVS) with the assistance of transformer leakage inductances and lossless capacitive snubbers. The new contribution of this work is that the passive semiconductor switches (diodes) on the secondary side can also perform ZVS and zero-current switching (ZCS) transitions with the assistance of voltage doubler capacitance. The theory of operation and the experimental setup of the proposed circuit with a rated output of 5 kW are presented and discussed. A comparison between simulation and experimental results is explored and illustrated.

高周波IH金属熱処理応用シングルステージAC-ACコンバータの検討

This paper presents a new single-stage utility frequency ac-high frequency ac resonant power converter for high frequency induction heating applications.The newly-proposed ac-ac converter features a boost converter and full bridge resonant inverter integrated circuit with a source voltage sensorless control system.The experimental results of a 3.0kW-40kHz prototype are demonstrated on zero voltage soft switching(ZVS) operations and steady-state character-istics,then the validity of the proposed ac-ac converter is revealed from a practical point of view.

A Bridgeless BHB ZVS-PWM AC–AC Converter for High-Frequency Induction Heating Applications

A new prototype of a zero voltage soft-switching (ZVS) utility frequency ac to high-frequency ac resonant power converter for induction heating (IH) applications is presented in this paper. The series resonant ac-ac converter proposed herein can process the frequency conversion without any diode bridge rectifier, thereby reducing the relevant conduction power losses. In addition, power factor correction (PFC) can be naturally achieved by the inductor-based boost half-bridge circuit with the nonsmoothed dc-link. The operation principle together with an IH load power regulation scheme is described, and the converter performances including ZVS operations and PFC are demonstrated in an experiment with a 3.0-kW-30-kHz prototype by comparing it with the previously developed converter. Finally, the feasibility of the proposed ac-ac converter is evaluated from a practical point of view.

A High‐Frequency‐Link Secondary‐Side Phase‐Shifted ZVS‐PWM DC–DC Converter with ZCS Active Rectifier

SUMMARYPerformance evaluations of a secondary‐side phase shift (SPS) pulse‐width‐modulation (PWM)‐controlled zero‐voltage soft‐switching (ZVS) dc–dc converter with a zero current soft‐switching (ZCS) active rectifier are presented in this paper. In the proposed dc–dc converter, soft‐switching operations are achievable from full to null loads by utilizing the parasitic inductances of the high‐frequency (HF) transformer. In addition, no circulating current emerges in either the primary‐ or secondary‐side full‐bridge circuits, and thus the related idling power losses can be minimized. In this paper, the soft‐switching operations over the wide‐range load variations are verified, and the characteristics of output power and voltage versus phase‐shift angle regulations are demonstrated in an experiment based on a 1 kW to 50 kHz laboratory prototype of the proposed dc–dc converter. Furthermore, the converter power losses, which include the switching and conduction power losses, are analyzed, after which the effectiveness of the proposed dc–dc converter is evaluated from a practical point of view.

Nonactive Power Loss Minimization in a Bidirectional Isolated DC–DC Converter for Distributed Power Systems

Originated from analyzing nonactive power loss, a novel optimization method and modulation solution for bidirectional isolated dual-active-bridge (DAB) dc-dc converters are proposed in order to achieve high efficiency in a wide operating range. A comprehensive nonactive power loss model is developed, including both the nonactive components delivered back to the source and from the load. This paper points out that when the minimum nonactive power loss is achieved, zero-voltage soft switching can be naturally fulfilled. The optimal phase-shift pair obtained by the proposed method can keep low values of both root mean square (RMS) current and circulating power. Rather than using ideal power flow analysis, the nonactive power loss model directly embodies practical nonideal factors, including device voltage drops. Based on the analysis, an extended dual phase shift is proposed, and different operation cases are analyzed with comparison of performance indices. Experimental tests verify the theoretical analysis and show effectiveness of the proposed approach to achieve nonactive power loss minimization and efficiency improvement.

A Load-Power Adaptive Dual Pulse Modulated Current Phasor-Controlled ZVS High-Frequency Resonant Inverter for Induction Heating Applications

A new prototype of an efficiency-improved zero voltage soft-switching (ZVS) high-frequency resonant (HF-R) inverter for induction heating (IH) applications is presented in this paper. By adopting the dual pulse modulation mode (DPMM) that incorporates a submode power regulation scheme such as pulse density modulation, pulse frequency modulation, and asymmetrical pulse width modulation into main one of the resonant current phase angle difference ( θ) control, the IH load power can be widely regulated under the condition of ZVS, while significantly improving the efficiency in the low output power setting. The essential performances on the output power regulations and ZVS operations with the DPMM schemes are demonstrated in an experiment based on a 1 kW-60 kHz laboratory prototype of the ZVS HF-R inverter. The validity of each DPMM scheme is originally compared and evaluated from a practical point of view.

A New Resonant Current Phase-Angle-Difference-Controlled Zero Voltage Soft-Switching High-Frequency Inverter and Its Experimental Evaluation

A novel zero voltage soft-switching (ZVS) high-frequency resonant (HF-R) inverter using a reverse-conducting insulated gate bipolar transistor (RC-IGBT) for induction heating (IH) applications is presented in this paper. By utilizing the newly developed fixed-frequency phase angle difference (θ) control of two resonant currents, the IH load power can be continuously regulated in the proposed HF-R inverter over a wide range of output power setting under the conditions of ZVS while maintaining high efficiency. Its operating principle is described with theoretical analysis and simulation results, after which the wide-range power regulation and full-range ZVS operations are clarified by theory and analysis. Furthermore, the essential characteristics on the output power regulations, ZVS operations, and actual conversion efficiency are demonstrated in an experiment with a 1kW-60kHz laboratory prototype of the proposed HF-R inverter. Finally, its feasibility is evaluated from a practical point of view.

A High-Frequency-Link Secondary-Side Phase-Shifted ZVS-PWM DC-DC Converter with ZCS Active Rectifier

Performance evaluations of a secondary-side phase shift (SPS) pulse-width-modulation (PWM)-controlled zero voltage soft-switching (ZVS) DC-DC converter with a zero current soft-switching (ZCS) active rectifier are presented in this paper. In the proposed DC-DC converter, the soft-switching operations are achievable from full to null loads by utilizing the parasitic inductances of the high-frequency (HF) transformer. In addition, no circulating current emerges in either the primary- or secondary-side full-bridge circuits, and thus the related idling power losses can be minimized. In this paper, the soft-switching operations over the wide-range load variations are verified, and the characteristics of output power and voltage versus phase shift angle regulations are demonstrated in an experiment based on a 1kW-50kHz laboratory prototype of the proposed DC-DC converter. Furthermore, the converter power losses, which include the switching and conduction power losses, are analyzed, after which the effectiveness of the proposed DC-DC converter is evaluated from a practical point of view.