Isolated Bidirectional DC-DC Switching With Phase-Shifted Bridge Control
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Solution Overview
Problem
Conventional isolated bidirectional DC-DC circuits face challenges in smoothly switching between forward and reverse operations due to frequency limitations, leading to voltage fluctuations and instability in power grids.
Innovation Solution
A method involving phase shifting and frequency adjustment of driving signals in bridge arm circuits to control output currents, ensuring smooth transitions by adjusting phases and frequencies to zero or near-zero levels before switching directions, thereby stabilizing power flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency conversion control is used to achieve wide voltage adjustment range, then voltage adjustment range is improved, but smooth switching between forward and reverse operation cannot be realized due to frequency limitation of switching device
Solution Approach 1:
The patent changes the control parameter from frequency conversion to phase shift control. By adjusting the phase difference between driving signals of the two bridge arm circuits while maintaining fixed switching frequency, the patent achieves both wide voltage adjustment range and smooth bidirectional switching without being constrained by switching device frequency limitations
Solution Approach 2:
The patent introduces a phase shift control mechanism as an intermediary between the two bridge arm circuits. This phase shift control acts as a mediator that enables smooth power transfer and bidirectional switching by gradually adjusting the phase difference, avoiding direct frequency conversion that would cause switching interruptions
2Adaptability or versatility
If conventional frequency conversion control is used, then voltage adjustment capability is improved, but voltage fluctuations and instability occur during switching operations
Solution Approach 1:
The patent ensures continuous power flow during bidirectional switching by maintaining both bridge arm circuits operating at the same fixed frequency. The phase shift control allows gradual transition of power direction without interruption, eliminating voltage fluctuations and maintaining system stability throughout the switching process
Data Source
AI summary
A method for switching between a forward operation and a reverse operation of an isolated bidirectional DC-DC circuit, a controller, a bidirectional converter, and a charging system are provided. The method includes: on receiving a switching signal, controlling a second bridge arm circuit to stop synchronous rectification, and adjusting phases of driving signals of two bridge arm branches in the first bridge arm circuit; in a case that the output current of the second bridge arm circuit reaches a first predetermined current, controlling the first bridge arm circuit to stop operating, and adjusting phases of driving signals of two bridge arm branches in the second bridge arm circuit; and in a case that the output current of the second bridge arm circuit reaches a second predetermined current, controlling the first bridge arm circuit to resume operating and perform synchronous rectification.