Phase-Shifted Dual-Bridge DC/DC Converter for Wide-Range ZVS
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Solution Overview
Problem
Existing power converters face challenges in achieving wide-range Zero Voltage Switching (ZVS), minimizing circulating current, recovering reverse recovery energy, and eliminating voltage ringing, while maintaining high efficiency and reducing Electromagnetic Interference (EMI) and size.
Innovation Solution
A dual-bridge DC/DC converter topology with a new control method that utilizes PWM and phase-shift controllers to operate at a constant 50% duty cycle, featuring symmetrical and isolated AC voltage output, synchronous rectification, and a resonant or non-resonant inverter configuration, which eliminates circulating current and maximizes energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duty cycle is reduced at light load to maintain ZVS, then switching loss increases, but if duty cycle is maintained, then ZVS cannot be achieved
Solution Approach 1:
The dual-bridge configuration enables each bridge to serve dual purposes: power delivery and ZVS support for the other bridge. The phase-shifted operation allows the bridges to mutually support each other's soft-switching requirements across the entire load range, eliminating the need to sacrifice ZVS capability at light loads.
2Loss of energy
If converter size is reduced using high-frequency switching, then efficiency improves, but EMI emission increases
Solution Approach 1:
The patent converts the potentially harmful high-frequency switching transients into beneficial resonant waveforms. By carefully designing the phase-shift control and bridge timing, the switching edges are shaped to create resonant current waveforms that naturally zero-cross at switch turn-on moments, reducing EMI while maintaining high-frequency operation for compact size and high efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves wide-range ZVS, minimizes power losses, reduces EMI, and enhances overall efficiency and performance by eliminating circulating current and effectively utilizing magnetic components, while maintaining a compact design.
Implementation Method 1
the circulating current and its corresponding energy stored in the transformer leakage inductance to energize a resonation between the capacitive elements of the leading leg's switching devices and the leakage inductance
Implementation Method 2
convert electrical energy from one DC voltage level to the other isolated levels by using high frequency switching technology
Data Source
AI summary
Disclosed is a family of new DC/DC converters and a new control method. The converter comprises two bridge inverters, two full-wave rectification circuits and a current-doubler filter. Each inverter is able to generate a symmetrical and isolated AC output voltage. Phase-shift control is employed to control the phase difference between the two bridge inverters. By shifting the phase, the converter changes the two inverters' output voltage overlapping area to regulate its output voltage. The bridge inverters always operate at 50% duty cycle, like an open loop Bus Converter, to achieve wide-range zero voltage switching and eliminate circulating current for normal operation. For low output voltage regulation and soft start, Pulse Width Modulation (PWM) control is used. The converters and the control method improve power conversion efficiency, maximize magnetic component utilization, reduce semiconductor stress and decrease EMI emission.