Full-bridge Pulsewidth Modulation Converter Research Articles

Hybrid DC-DC Converter with Low Switching Loss, Low Primary Current and Wide Voltage Operation

A full-bridge converter with an additional resonant circuit and variable secondary turns is presented and achieved to have soft-switching operation on active devices, wide voltage input operation and low freewheeling current loss. The resonant tank is linked to the lagging-leg of the full bridge pulse-width modulation converter to realize zero-voltage switching (ZVS) characteristic on the power switches. Therefore, the wide ZVS operation can be accomplished in the presented circuit over the whole input voltage range and output load. To overcome the wide voltage variation on renewable energy applications such as DC wind power and solar power conversion, two winding sets are used on the output-side of the proposed converter to obtain the different voltage gains. Therefore, the wide voltage input from 90 to 450 V (Vin,max = 5Vin,min) is implemented in the presented circuit. To further improve the freewheeling current loss issue in the conventional phase-shift pulse-width modulation converter, an auxiliary DC voltage generated from the resonant circuit is adopted to reduce this freewheeling current loss. Compared to the multi-stage DC converters with wide input voltage range operation, the proposed circuit has a low freewheeling current loss, low switching loss and a simple control algorithm. The studied circuit is tested and the experimental results are demonstrated to testify the performance of the resented circuit.

Resonant Converter with Soft Switching and Wide Voltage Operation

A new DC/DC resonant converter with wide output voltage range operation is presented and studied to have the benefits of low switching losses on active devices and low voltage stresses on power diodes. To overcome serious reverse recovery losses of power diodes on a conventional full-bridge pulse-width modulation converter, the resonant converter is adopted to reduce the switching loss and increase the circuit efficiency. To extend the output voltage range in conventional half-bridge or full-bridge resonant converters, the secondary sides of two diode rectifiers are connected in series to have wide output voltage operation. The proposed converter can be either operated at one-resonant-converter mode for low voltage range or two-resonant-converter mode for high voltage range. Thus, the voltage rating of power diodes is decreased. Experiments with the design example are given to show the circuit performance and validate the theoretical discussion and analysis.

Analysis and Mitigation of Dead-Time Harmonics in the Single-Phase Full-Bridge PWM Converter With Repetitive Controllers

In order to prevent the power switching devices (e.g., an insulated-gate bipolar transistor, IGBT) from shoot-through in voltage-source converters during a switching period, the dead time is added either in the hardware driver circuits of the IGBTs or implemented in software in pulse width modulation (PWM) schemes. Both solutions will contribute to a degradation of the injected current quality. As a consequence, the harmonics induced by the dead time (referred to as “dead-time harmonics” hereafter) have to be compensated in order to achieve a satisfactory current quality, as required by standards. In this paper, the emission mechanism of dead-time harmonics in single-phase PWM inverters is, thus, presented considering the modulation schemes in detail. More importantly, a repetitive controller has been adopted to eliminate the dead-time effect in single-phase grid-connected PWM converters. The repetitive controller has been plugged into a proportional-resonant-based fundamental-frequency current controller so as to mitigate the dead-time harmonics and also to maintain the control of the fundamental-frequency grid current in terms of dynamics. Simulations and experiments are provided, which confirm that the repetitive controller can effectively compensate the dead-time harmonics and other low-order distortions, and also, it is a simple method without hardware modifications.

Analysis of Strategy for Achieving Zero-Current Switching in Full-Bridge Converters

Conventional zero-voltage and zero-current-switching (ZVZCS) full-bridge converters are widely used because they can realize zero-voltage switching (ZVS) for the leading leg and zero-current switching (ZCS) for the lagging leg. However, the large turn-off loss of the leading leg is still unacceptable in high-voltage high-power applications where insulated-gate bipolar transistors (IGBTs) with current tailing are employed. Hence, it is preferable to achieve ZCS for all IGBTs of full-bridge converters. This paper analyzes the ZCS conditions for pulsewidth modulated (PWM) full-bridge converters and proposes a general strategy for achieving ZCS for main switches, including the control strategy and design method of the topology. Based on this theory, a novel ZCS PWM full-bridge converter with simple auxiliary circuit is derived and tested. It can achieve ZCS not only for the main switches of full-bridge converter, but for the auxiliary switch as well, and obtain high efficiency. The operation principle of the proposed ZCS PWM full-bridge converter and the design procedure are presented. The experimental results of a 600 V/2.5 kW prototype are also included to verify the theoretical analysis.

High-voltage power supply using series-connected full-bridge PWM converter for pulsed power applications

This paper presents a capacitor charging power supply (CCPS) using high-voltage dc/dc converter for pulsed power applications. For the main converter, it used full-bridge phase-shifted (FBPS) pulse-width modulation (PWM) converter. The proposed CCPS has modularity concept, and the output voltage was boosted by a high-voltage high-frequency (HVHF) transformer included in FBPS PWM converter. The control method is used a phase-shifted PWM to reduce the losses caused by switching. To solve the voltage unbalancing problem of the output capacitors, synchronization algorithm is selected. Also Thermal characteristics are analyzed by theoretical calculation and simulation. Experimental results of the single module and CCPS are provided to validate the effectiveness of the proposed system and it was carried out the 20-kV 160-kW prototype.

A Soft Switching Full Bridge Converter With Reduced Parasitic Oscillation in a Wide Load Range

A phase-shift zero voltage switching (ZVS) pulse width modulation full-bridge converter with reduced parasitic oscillation across the rectifier is proposed. The introduced auxiliary transformer used as a voltage source forces the primary current commutating in advance. Parasitic voltage oscillation at secondary is well reduced and there is no duty cycle loss. ZVS of primary switches can be achieved in much wide load range with the help of an auxiliary coupled inductor, and the main transformer continuously transfers energy to load in a whole switching cycle, resulting in no circulating time, and ripple current flowing through the output filter inductor decreases significantly. In this paper, operation principle of the circuit is analyzed in detail. Besides, discussion of key characteristics and design considerations are also included. Finally, experimental results from a 480-W/48-V, 100-kHz prototype are presented to confirm the superior features of the proposed converter.

Zero-Voltage-Switching PWM Full-Bridge Converter Employing Auxiliary Transformer to Reset the Clamping Diode Current

Introducing clamping diodes into the zero-voltage-switching (ZVS) pulsewidth-modulation (PWM) full-bridge (FB) converters can eliminate the voltage oscillation across the output rectifier diodes; however, the clamping diodes result in increase in conduction loss and suffer from serious reverse recovery at light load. In order to solve these problems, the clamping diode current should be reset rapidly. This paper proposes a scheme of resetting the clamping diode current over the full-load range by introducing an auxiliary transformer into the ZVS PWM FB converter. The operation principles of the proposed scheme under heavy-load and light-load conditions are analyzed in details. The design considerations of the introduced auxiliary transformer are also given. A performance comparison among the proposed scheme of resetting the clamping diode current and other ones are addressed. Experimental results verify the effectiveness of the analysis and prove that the proposed converter has improved reliability and reduced conduction loss compared with the classical one.

Zero-Voltage Switching and Soft-Commutating Two-Transformer Full-Bridge PWM Converter Using the Voltage-Ripple

A zero-voltage switching (ZVS) and soft-commutating two-transformer full-bridge pulsewidth modulation converter using the voltage ripple is proposed in this paper. It is based on the phase-shift full-bridge with series-connected two transformers (TTFB) that act as an output inductor as well as a main transformer. Moreover, the TTFB converter achieves the ZVS of all the switches inherently even at a light load using the energy stored in the magnetizing inductance of each transformer. However, it has several drawbacks such as circulating energy during the freewheeling state, loss of duty cycle, and high voltage stress across the output rectifier diodes. To overcome these drawbacks, the proposed converter employs an output-voltage-doubler, allowing the output rectifier diode to softly commutate with less voltage stress, to reduce the freewheeling interval as well as the circulating energy. The operational principle, technical analysis, and design considerations are described. Finally, the experimental results from a 425 W, 385 Vdc /170 Vdc prototype are presented to confirm the operation, validity, and features of the proposed converter.

A New PWM ZVS Full-Bridge Converter

A soft-switched full-bridge (FB) converter that features zero-voltage-switching (ZVS) of the bridge switches over a wide output-load range is introduced. The proposed converter achieves ZVS with substantially reduced duty-cycle loss and circulating current. The control of the proposed converter can be implemented either with the phase-shift or pulsewidth modulated (PWM) technique. The performance of the proposed topology was verified on a 2-kW (48-V/40-A) experimental PWM FB converter prototype operating at 120 kHz from a 380-V dc input

A Novel Zero-Voltage and Zero-Current-Switching Full-Bridge PWM Converter

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulse-width modulation converter is proposed. The ZCS condition of the lagging-leg is obtained by a simple secondary auxiliary circuit resetting the primary current during the freewheeling stage. The auxiliary circuit's capacitor is charged by the center tape of the secondary through a diode, and the capacitor's voltage is clamped through another diode to output capacitor, thus, the voltage stress on the rectifier is clamped. There are neither additional active switches nor resistances in the auxiliary circuit, which makes the proposed converter efficient.

Pwm Full-bridge converter with natural input power factor correction

A pulsewidth modulated (PWM) full-bridge converter that simultaneously performs input power factor correction (PFC) and DC-DC conversion is proposed. The converter is the same as the standard voltage-fed PWM full-bridge converter with a diode-bridge low-pass filter front end, but with a slight modification that results in an improvement in power factor that is sufficient to satisfy the EN61000-3-2 requirements for electrical equipment. The operation of the converter is explained and analyzed, and the results of the analysis are used to determine the converter's steady-state characteristics, which are discussed in detail. A design procedure for the selection of components is then derived and demonstrated with an example. The feasibility of the converter and its ability to satisfy EN61000-3-2 requirements on electrical equipment is shown with results obtained from an experimental prototype.

A novel zero-voltage and zero-current-switching PWM full-bridge converter using two diodes in series with the lagging leg

This paper proposes a novel phase-shifted zero-voltage and zero-current-switching (ZVZCS) pulsewidth modulation full-bridge converter, which realizes ZVS for the leading leg and ZCS for the lagging leg. A blocking capacitor is added in series with the primary winding of the transformer to make the primary current decay to zero during zero state to ensure ZCS for the lagging leg. In order to prevent the primary current from reversing during zero state, two diodes in series with the lagging leg are added. The principle of operation, steady-state analysis, and design procedures are presented. The experimental results are also included to verify the theoretical analysis.

A simple ac-dc pwm full-bridge converter with integrated power-factor correction

A simple ac-dc pulsewidth-modulation (PWM) converter that can perform isolated dc-dc conversion while shaping the input current to improve power factor is proposed in this paper. The converter is almost the same as a standard PWM full-bridge converter with a diode rectifier/LC low-pass filter input except for some slight modifications. The converter topology is, therefore, very simple, as is the method of control used to achieve both power-factor correction and dc-dc conversion. In the paper, the operation of the converter is explained and analyzed, and the converter's steady-state characteristics are discussed. A design procedure for the selection of components is presented, and then demonstrated with an example. The feasibility of the converter, and its ability to meet EN61000-3-2 Class D standards for electrical equipment is shown with results obtained from an experimental prototype.

Novel zero-voltage and zero-current-switching full bridge PWM converter using transformer auxiliary winding

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) pulse width modulation (PWM) converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters, such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high power (>2 kW) applications. The operation, analysis, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz insulated gate bipolar transistor (IGBT) based experimental circuit.

Novel zero-voltage and zero-current-switching full-bridge PWM converter using a simple auxiliary circuit

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulsewidth modulation converter is presented to simplify the circuits of the previously presented ZVSCS converters. A simple auxiliary circuit, which consists of one small capacitor and two small diodes, is added in the secondary to provide ZVZCS conditions to primary switches, as well as to clamp secondary rectifier voltage. The additional clamp circuit for the secondary rectifier is not necessary. The auxiliary circuit includes neither lossy components nor additional active switches, which makes the proposed converter efficient and cost effective. The principle of operation, features, and design considerations are illustrated and verified on a 2.5 kW 100 kHz insulated-gate-bipolar-transistor-based experimental circuit.

Zero-voltage and zero-current-switching full bridge PWM converter for high-power applications

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse-width modulated (PWM) converter is proposed. The new converter overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and limited ZVS load range for the lagging-leg switches. By using the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging-leg switches to be operated with zero-current-switching (ZCS). Meanwhile, the leading-leg switches are still operated with ZVS. The new converter is attractive for high-voltage (400-800 V), high-power (2-10 kW) applications where IGBTs are predominantly used as the power switches. The principle of operation, features, and design considerations of the new converter are described and verified on a 2-kW, 100-kHz, IGBT-based experimental circuit.

A novel soft-switching full-bridge DC/DC converter: analysis, design considerations, and experimental results at 1.5 kW, 100 kHz

The authors present an improved soft-switching full-bridge converter which is especially suitable for high-power application (e.g. more than 1 kW output) because of its inherently high efficiency. The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulse width modulation) full-bridge DC-DC converter substantially reduced the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors analyze the conditions for lossless transitions, discuss the effect of the added components on the operation of the converter, and present practical considerations and test results for a 1.5 kW converter with 100 kHz clock frequency. The converter has an efficiency above 95% at 60 V output, is free from voltage overshoots, and exhibits well-controlled transitions for all switch and rectifier voltages and currents. >