A ZVS Pulsewidth Modulation Full-Bridge Converter With a Low-RMS-Current Resonant Auxiliary Circuit

2019

Energies

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.

Section: Introductionmentioning

confidence: 99%

Resonant Converter with Soft Switching and Wide Voltage Operation

2019

Energies

“…High power density and high circuit efficiency are demanded of modern powered electronics in order to reduce the greenhouse effect. Power converters with soft switching characteristics, such as asymmetric pulse-width modulation converters [1][2][3][4] and phase-shift pulse-width modulation converters [5][6][7][8], have been developed and implemented to improve converter efficiency. The main drawback of these circuit topologies is a narrow soft switching range due to the limited energy stored on the leakage inductor under light or low load.…”

Section: Introductionmentioning

confidence: 99%

Resonant Converter with Voltage-Doubler Rectifier or Full-Bridge Rectifier for Wide-Output Voltage and High-Power Applications

Jian³

2018

Electronics

This paper presents a resonant converter with the benefits of wide output voltage, wide soft switching characteristics for power devices and high circuit efficiency. Since the series resonant circuit is adopted on the primary side, the power switches are turned on under zero voltage switching and power diodes on the secondary side can be turned off under zero current switching. To overcome the drawback of narrow voltage operation range in the conventional resonant converter, full-bridge rectifier and voltage-doubler rectifier topologies are employed on the secondary side for low-voltage output and high-voltage output applications. Therefore, the voltage rating of power devices on the secondary side is clamped at output voltage, rather than two times output voltage, in the center-tapped rectifier circuit. Synchronous power switches are used on the secondary side to further reduce the conduction losses so that the circuit efficiency can be further improved. To verify the theoretical analysis and circuit performance, a laboratory prototype with 1 kW rated power was built and tested.2 of 16 needed for EV and HEV applications or outdoor LED lighting systems with variable series or parallel combinations of LED strings. There are several solutions to overcome the challenges of wide input or output voltage range operation. First, the conventional full-bridge converter, as shown in Figure 1a, with wide duty cycle control can be adopted to achieve wide voltage operation. If the maximum duty cycle is four times the minimum duty cycle (d max = 4 d min ), then the output voltage of full-bridge converter is controlled at the constant value for 4:1 input voltage range (v max = 4 v min ). However, wide duty cycle operation will result in low circuit efficiency in cases of high input voltage and low duty cycle. The second solution to achieve wide voltage operation is using two-stage dc-dc converters, as shown in Figure 1b, such as buck or boost circuit and full-bridge circuit. Since two-stage circuits are used, the circuit efficiency is decreased and the circuit reliability is also reduced. The third solution is using single stage hybrid resonant circuit topology [12][13][14] as shown in Figure 1c. The wide voltage range resonant converter with full-bridge circuit (S 1~S4 are operation) or half-bridge (S 1 , S 2 and S 3 are operation) circuit topology used on the primary side [13,14] has been proposed to extend the input voltage range. The main advantage of the full-bridge and half-bridge resonant converter on the primary side is the wide input voltage range (v in,max = 4 v in,min ). However, there is a transient duration between the half-bridge resonant converter and the full-bridge resonant converter operation, and one power switch S 3 is always in the on-state under half-bridge resonant circuit, which will result in one more conduction loss on a powered device. The secondary side of the circuit topologies in Figure 1 is the center-tapped rectified circuit with two diodes to obtain low voltage output. If a wide output voltage i...

“…Zero-voltage switching converters [12][13][14][15] have been proposed to achieve a low switching loss. Asymmetric pulse-width modulation [16][17][18], frequency modulation [19][20][21] and a phase-shift pulse-width modulation (PWM) scheme [22][23][24] are general PWM control schemes used in DC/DC converters to regulate load voltage and also realize the mechanism of the zero-voltage turn-on switching. Therefore, the high efficiency converters can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Series-Connected High Frequency Converters in a DC Microgrid System for DC Light Rail Transit

2018

Energies

This paper studies and presents a series-connected high frequency DC/DC converter connected to a DC microgrid system to provide auxiliary power for lighting, control and communication in a DC light rail vehicle. Three converters with low voltage and current stresses of power devices are series-connected with single transformers to convert a high voltage input to a low voltage output for a DC light rail vehicle. Thus, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) with a low voltage rating and a turn-on resistance are adopted in the proposed circuit topology in order to decrease power losses on power switches and copper losses on transformer windings. A duty cycle control with an asymmetric pulse-width modulation is adopted to control the output voltage at the desired voltage level. It is also adopted to reduce switching losses on MOSFETs due to the resonant behavior from a leakage inductor of an isolated transformer and output capacitor of MOSFETs at the turn-on instant. The feasibility and effectiveness of the proposed circuit have been verified by a laboratory prototype with a 760 V input and a 24 V/60 A output.