Zero-voltage Switching Converter Research Articles

Transformer-Less Soft-Switching High-Gain PWM Boost Converter With Reduced Components and Increased Effective Duty Cycle

A transformer-less soft-switching high-gain pulsewidth-modulation (PWM) converter is proposed in this article. The proposed converter is derived from a single-switch dual-inductor transformer-less boost converter by replacing the complementary diode connected to the switch with a synchronous rectifier switch. Moreover, the peak value of the reverse current of the rear-end inductor in continuous bidirectional conduction mode (CBCM) is regulated to exceed the input inductor valley current. Based on these two measures, the zero-voltage switching (ZVS) for all switches and the natural turn-off for the output diode are realized, and the effective duty cycle is enhanced. Besides, the proposed ZVS converter has the merits of fewer power components count, reduced voltage stress, and lower cost. Furthermore, the ringing issue in the original topology under light load or high input voltage conditions is eliminated. The operation principle, steady-state characteristics, dynamic model, soft-switching operation, and realization conditions are analyzed in detail, and subsequently, the parameter design method is elaborated. The proposed topology demonstrates an enhanced efficiency performance over wide operating operations with a maximum efficiency of 97.1%.

A Universal ZVT Design for a Family of Multiphase Interleaved High Step-Up Converters With Minimized Voltage Stress and Wide Operating Range

Multiphase interleaved boost diode-capacitor (MIBD) converters, as the combination of multiphase interleaved input and voltage multiplier cells (VMCs), provide a preferred solution for both high voltage gain and high-efficiency application. This article proposes a universal zero-voltage transition (ZVT) circuit design method for a family of MIBD converters with different VMC structure and cell number. Compared with other soft-switching (SS) design methods, there is no extra voltage stress for all the semiconductor devices. An auxiliary circuit consisting of two low-voltage rating switches, two diodes, two capacitors, and one small inductor is integrated into the hard-switching (HS) two-phase interleaved boost diode-capacitor (TIBD) converters to provide zero-voltage switching (ZVS) turn-on and turn-off for the main switches and zero-current switching (ZCS) turn-off for all the diodes. Besides, the auxiliary switches turn on under ZCS. All the SS is accomplished within a wide duty cycle and power rating. From the comprehensive comparison, the constructed converters' performance exceeds that of ZVS converters published in the recent literature. Furthermore, the extendable high voltage gain, low input current ripple, low voltage stress, and simple parameter design characteristics of HS MIBD converters are also conserved. Finally, a 320-W laboratory prototype is implemented to validate the theoretical analysis.

Implementation of 48 V Series-Input Parallel-Output Zero-Voltage Switching Converter Using Secondary Resonant Technique

This research paper aims to propose a series-input parallel-output zero-voltage switching converter (SIPO ZVS converter) by using the secondary resonant technique for achieving the Zero-Voltage-Switching (ZVS) condition for all the main switching devices in the proposed converter. Two half-bridge converters are applied for the proposed converter, connected in series at the input side and in parallel at the output side of the proposed converter (SIPO technique). By using the SIPO technique, the voltage stress on the main switching devices is decreased to be a half of the input voltage or Vdc/2. This leads to the reduction of rated voltage of main switching devices. The rated current of the rectifier diodes is also decreased because of the current sharing behavior. Moreover, the phase-shifted control method is analyzed in order to comprehend the impact on the ripple current at the output side. Finally, the prototype of the proposed converter has been designed, built, and tested in order to confirm the effectiveness of the proposed converter.

Analysis of a Three-Level Bidirectional ZVS Resonant Converter

A bidirectional three-level soft switching circuit topology is proposed and implemented for medium voltage applications such as 750 V dc light rail transit, high power converters, or dc microgrid systems. The studied converter is constructed with a three-level diode-clamp circuit topology with the advantage of low voltage rating on the high-voltage side and a full-bridge circuit topology with the advantage of a low current rating on the low-voltage side. Under the forward power flow operation, the three-level converter is operated to regulate load voltage. Under the reverse power flow operation, the full-bridge circuit is operated to control high-side voltage. The proposed LLC resonant circuit is adopted to achieve bidirectional power operation and zero-voltage switching (ZVS). The achievability of the studied bidirectional ZVS converter is established from the experiments.

Adaptive Hysteresis Current Based ZVS Modulation and Voltage Gain Compensation for High-Frequency Three-Phase Converters

This article proposed a systematic approach for the control of three-phase bidirectional zero-voltage switching (ZVS) converters. Combining the adaptive hysteresis-band current control and turn- on delay modifications, ZVS conditions are realized in full line-cycle in all loading conditions like active power, reactive power, light load, and heavy load. The soft-switching resonant period is carefully analyzed, and the current band is designed accordingly, which minimized the additional conduction loss. Meanwhile, a zero-sequence voltage injection control is included in the approach, which compensates the voltage gain by 15% and narrows down the switching frequency variation range. The hardware design approach is also provided including the LCL filter design and a low-cost high-bandwidth high-accuracy current sensor design. A highly integrated 5-kW silicon carbide implemented three-phase ZVS converter prototype with printed circuit board integrated inductors and customized current sensors is designed. All the control is implemented in a single microcontroller unit, which achieves a high electromagnetic compatibility. The designed prototype achieves a total power density of 5.5 kW/L and a peak efficiency of 98.5%. All the analysis and the proposed control approach are experimentally verified on the designed prototype.

Large Power Hybrid Soft Switching Mode PWM Full Bridge DC–DC Converter With Minimized Turn-on and Turn-off Switching Loss

A novel PWM full bridge (FB) dc–dc converter for large power industrial applications is proposed in this paper. The soft switching mode of the primary switches can be varied under different input and output conditions to achieve optimum system efficiency. In the zero-voltage and zero-current switching (ZVZCS) mode, the turn- on and turn- off switching loss can be optimized because the soft switching conditions of the turn- on and turn- off instants are well decoupled. In the zero-voltage switching (ZVS) mode, the turn- off switching loss can also be optimized because there is no requirement for light load operation in this mode. Four mosfet s with ultra-low on-state resistance are used, thus, the added conduction loss is small. The auxiliary mosfet s with high switching frequency are turned on with zero-current and off with zero-voltage, hence, the added switching loss can also be neglected. Furthermore, some drawbacks of the conventional ZVS and ZVZCS converters, e.g., narrow ZVS load range, high primary circulating current, incomplete reset of the primary current, and unreasonable VA rating of the added components, have been well solved. The operation principles and soft switching characteristics are discussed. Experimental results from an 18-kW prototype are provided to verify the proposed converter.

Lumped parameter model of the novel L‐C‐T used in the PSFB ZVS converter

A novel inductor-capacitor-transformer (L-C-T) has been proposed to integrate the passive components into an integrated magnetic component. The phase-shift full-bridge (PSFB) zero-voltage switching (ZVS) converter with a novel L-C-T has high-power density performance, which is used in electromagnetic exploration. The structure of the novel L-C-T is very complicated, and the lumped parameter of the L-C-T is very difficult to determine. Based on the dual method of the magnetic circuit, the electromagnetic energy method and the six-lumped capacitance method, a lumped parameter model suitable for the novel L-C-T is proposed. Moreover, the experiments and finite element analysis (FEA) are used to verify the accuracy of the lumped parameter model, and a 40 kW prototype of the PSFB ZVS converter with a novel L-C-T is designed and tested.

Modular zero‐voltage switching converter for direct current microgrid applications

This study presents a high-voltage zero-voltage switching converter with balance capacitors in the direct current microgrid. In the proposed converter, full-bridge circuits with primary-series and secondary-parallel connection are used for high-voltage input and high-current output applications. The series connection of full-bridge circuits reduces the voltage rating of power switches in each full-bridge circuit cell. Therefore, high-speed power metal–oxide–semiconductor field-effect transistors are employed to reduce the converter size. Flying capacitors are connected between each full-bridge circuits so that the input split voltages can be balanced automatically in every switching period without using the complexity control scheme. The phase-shift pulse-width modulation scheme is used to regulate the output voltage. The power switches can be turned on at zero voltage due to the energy stored in the output inductors or primary leakage inductors and the switching losses are reduced. The output sides of the full-bridge circuits are connected in parallel to reduce the current ratings of transformer secondary windings and passive power components. Finally, experiments are provided to validate the characteristics and usefulness of the proposed converter in microgrid applications.

Analysis and Design of Solar Power System Interface Utility Using ZVS Converter

The solar power generation system with minimal losses, high simplicity and easy control is attempted in this work , by developing a grid-tied zero-voltage switching ( ZVS) inverter with a less number of power conversion stages and the least count of passive components, for single-phase applications that are suitable for conversion from low-voltage DC (40-60 V) to line voltage AC ( 230 VAC; RMS) at average power levels of 175 W and below. The ZVS full-bridge inverter fed from a PV panel is working on higher frequency with an asymmetric auxiliary circuit , which guarantees ZVS at the switching instants of the metal-oxide-semiconductor field-effect transistors (MOSFETs) by supplying the reactive current to these full-bridge semiconductor switches and reducing the switching losses. Checking of the constructional workability and analytical feasibility of the proposed topology with the highest efficiency and the simplest control was the target of this work, which was set on the basis of the results obtained in the MATLAB Simulink environment. The control strategies were planned for the optimum value of the reactive current injected by the auxiliary circuit to guarantee ZVS and use of phase shifted pulsewidth modulation (PWM) with varying frequencies for the full-bridge inverter and half-bridge cyclo-converter. The hybrid maximum power point tracking (MPPT) was part of this plan used to set the power at its maximum value against the environmental changes. Citation: Deshbhratar, R. G., and Renge, M. M. (2018). Analysis and Design of Solar Power System Interface Utility Using ZVS Converter. Trends in Renewable Energy, 4, 83-101. DOI: 10.17737/tre.2018.4.3.0052

Design of a Novel Integrated L-C-T for PSFB ZVS Converters

To enhance the zero-voltage switching (ZVS) range and power density of the phase-shift full-bridge (PSFB) ZVS converters used in geophysical exploration, an additional resonant inductor is used as a leakage inductance and a blocking capacitor which is equivalent to interlayer capacitance is integrat...

ZVS Converter with Full-Bridge and Half-Bridge Circuits: Analysis, Design and Implementation

A new DC/DC converter integrating a full-bridge circuit and a half-bridge pulse-width circuit is studied to realize the advantages of a wide range of zero-voltage switching (ZVS) and less circulating current loss. A half-bridge converter is connected to power switches on the lagging-leg of full-bridge converter to achieve a wider range of ZVS to overcome the disadvantage of narrow ZVS range in conventional full-bridge converter. The output side of half-bridge circuit is linked to the secondary side of the full-bridge converter to decrease the primary circulating current of the full-bridge converter. Therefore, the conduction losses due to the high circulating current in conventional full-bridge converter are reduced. The theoretical analysis is discussed in detail and the effectiveness of the proposed converter is verified by the experimental verifications with a 1440[Formula: see text]W prototype.

A Family of Magnetic Coupling DC-DC Converters With Zero-Voltage-Switching Over Wide Input Voltage Range and Load Variation

This paper presents a family of soft-switching DC-DC converters with a simple auxiliary circuit consisting of a coupled winding and a pair of auxiliary switch and diode. The auxiliary circuit is activated in a short interval and thus the circulating conduction losses are small. With the auxiliary circuit, zero-voltage-switching (ZVS) and zero-current-switching are achieved for the main and auxiliary switches respectively, over wide input voltage range and load variation. In addition, the reverse-recovery problem of diodes is significantly alleviated because of the leakage inductor. Furthermore, the coupled inductor simultaneously serves as the main and auxiliary inductors, contributing to reduced magnetic component in comparison with the conventional zero-voltage-transition (ZVT) converters. Experimental results based on a 500 W prototype buck circuit validate the advantages and effectiveness of the proposed magnetic coupling ZVS converter.

Zero‐voltage‐switching buck converter with low‐voltage stress using coupled inductor

This study presents a new zero-voltage-switching (ZVS) buck converter. The proposed converter utilises a coupled inductor to implement the output filter inductor as well as the auxiliary inductor which is commonly employed to realise ZVS for switches. Additional magnetic core for the auxiliary inductor in traditional ZVS converters is eliminated and hence reduced cost is achieved. Moreover, thanks to the series connection between the input and output, the switch voltage stress in the steady state is reduced and thus the ZVS operation can be easier achieved. Then the leakage inductor current circulating in the auxiliary switch is decreased, contributing to reduced conduction losses. In particular, low-voltage rating devices with low on-state resistance can be adopted to further improve efficiency in applications with non-zero output voltage all the time, such as the battery charger. Furthermore, the reverse-recovery problem of the diode is significantly alleviated by the leakage inductor of coupled inductor. In the study, operation principle and steady-state analysis of the proposed converter are presented in detail. Meanwhile, design considerations are given to obtain circuit parameters. Finally, simulations and experiments on a 200 W prototype circuit validate the advantages and effectiveness of the proposed converter.

Hybrid ZVS Converter with a Wide ZVS Range and a Low Circulating Current

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) <TEX>$\approx$</TEX> f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

New Parallel ZVS Converter With Less Active Switches and Smaller Output Inductance

This paper presents a new three-level zero-voltage switching (ZVS) dc/dc converter for high input voltage applications. There are two ZVS circuits in the proposed converter to share load current. Thus, the size of the output chokes is reduced. These two circuits use the same power switches. Thus, the proposed converter has less switch counts compared with the conventional parallel three-level ZVS dc/dc converter. In the proposed converter, each circuit combines one half-bridge converter and one three-level converter. The transformer secondary windings of two converters are connected in series to reduce the size of output inductor. The voltage stress of each power switch is limited at one-half of input voltage due to three-level circuit topology. Based on the resonant behavior by the output capacitance of active switches and the leakage inductance (or external inductance) at the transition interval, power switches are turned on at ZVS within the desired load range. Experiments based on a 1.5 kW prototype are provided to demonstrate the performance of the proposed converter.

Novel topology for DC/DC unidirectional converter for fuel cell

This study presents a new isolated DC/DC converter of full-bridge to connect a fuel cell to DC bus in a hybrid distribution generation system. This converter consists of a high-frequency transformer and a voltage booster circuit. The circuit has been designed and each isolated-gate bipolar transistor (IGBT) presents soft-switching during the whole power range of the converter. The switching losses of the IGBTs, the reverse-recovery losses of all of the diodes, and the core losses have almost been eliminated. To improve the efficiency, transformer cores and inductors have been built with material nanocrystalline. The efficiency is improved if this is compared with that of a conventional zero-voltage switching converter. Also, this converter can obtain a high-voltage gain and medium and high DC power can be converted. The analysis and switching techniques have been reported. Finally, to verify the principle of operation, a laboratory prototype of 2 kW has been performed.

Analysis, Design and Implementation of an Interleaved Single-Stage AC/DC ZVS Converters

An interleaved single-stage AC/DC converter with a boost converter and an asymmetrical half-bridge topology is presented to achieve power factor correction, zero voltage switching (ZVS) and load voltage regulation. Asymmetric pulse-width modulation (PWM) is adopted to achieve ZVS turn-on for all of the switches and to increase circuit efficiency. Two ZVS half-bridge converters with interleaved PWM are connected in parallel to reduce the ripple current at input and output sides, to control the output voltage at a desired value and to achieve load current sharing. A center-tapped rectifier is adopted at the secondary side of the transformers to achieve full-wave rectification. The boost converter is operated in discontinuous conduction mode (DCM) to automatically draw a sinusoidal line current from an AC source with a high power factor and a low current distortion. Finally, a 240W converter with the proposed topology has been implemented to verify the performance and feasibility of the proposed converter.

Interleaved DC-DC Converters with Partial Ripple Current Cancellation

An interleaved PWM converter is proposed to implement the features of zero voltage switching (ZVS), load current sharing and ripple current reduction. The proposed converter includes two ZVS converters with a common clamp capacitor. With the shared capacitor, the charge balance of the two interleaved parts is automatically regulated under input voltage and load variations. The active-clamping circuit is used to realize the ZVS turn-on so that the switching losses on the power switches are reduced. The ZVS turn-on of all of the switching devices is achieved during the transition interval. The interleaved pulse-width modulation (PWM) operation will reduce the ripple current and the size of the input and output capacitors. The current double rectifier (CDR) is adopted in the secondary side to reduce output ripple current so that the sizes of the output chokes and capacitor are reduced. The circuit configuration, operation principles and design considerations are presented. Finally experimental results based on a 408W (24V/17A) prototype are provided to verify the effectiveness of the proposed converter.

Analysis and Implementation of an Interleaved ZVS Converter with High Input Voltage

ABSTRACTAn interleaved half‐bridge converter is presented for high input voltage application. The features of the proposed converter are zero voltage switching (ZVS) turn‐on for all active switches, ripple current reduction at output side, load current sharing and load voltage regulation. Two half‐bridge converters connected in series and two split capacitors are used to limit the voltage stress of each power switch at one‐half of input DC bus voltage. Thus, active switches with low voltage stress can be used at high input voltage application. On the other hand, the output sides of two half‐bridge converters are connected in parallel to share the load current and reduce the current stresses of the secondary windings and the rectifier diodes. Since two half‐bridge converters are operated with interleaved pulse‐width modulation (PWM), the output ripple current can partially cancel each other such that the resultant ripple current at output side is reduced and the size of output inductors can be reduced. In each half‐bridge converter, asymmetrical PWM scheme is used to regulate the output voltage. Based on the resonant behavior by the output capacitance of MOSFETs and the leakage inductance (or external inductance) of transformers, active switches can be turned on at ZVS during the transition interval. Thus, the switching losses of power MOSFETs are reduced. The proposed converter can be applied for high input voltage applications such as three‐phase 380‐V utility system. Finally, experiments based on a laboratory prototype with 960‐W rated power are provided to demonstrate the performance of proposed converter. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Implementation of an interleaved pulse‐width modulation converter for renewable energy conversion

SUMMARYThis paper presents an interleaved soft switching converter to achieve the features of zero voltage switching (ZVS) turn‐on for power switches, zero current switching turn‐off for rectifier diodes at full load, less transformer secondary winding with full‐wave diode rectifier topology, and balance primary currents with series connection of the transformer secondary windings. Two circuit modules are adopted in the proposed circuit, and they are operated with an interleaved pulse‐width modulation. Thus, ripple currents at the input and output sides are reduced. In each module, two ZVS converters using the same switches are operated with interleaved half switching cycle. The secondary windings of transformers are connected in series in order to ensure that the primary side currents are balanced. The full‐wave diode rectifier topology is used on the output side such that the voltage stress of rectifier diodes equals output voltage, rather than being two times the output voltage as in a conventional center‐tapped rectifier topology. Laboratory experiments with a 1000‐W prototype are provided to describe the effectiveness of the proposed converter. Copyright © 2011 John Wiley &amp; Sons, Ltd.