Mixed Control for Resonant Converter Voltage Gain
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Solution Overview
Problem
Resonant converters face high circuit loss and efficiency issues when operating under abnormal conditions, such as low voltage gain or limited output current, due to existing control methods that either increase frequency or change pulse width, leading to potential converter damage.
Innovation Solution
A mixed control method for resonant converters that adjusts both the operating frequency and phase-shifting angle by setting mixed control start and stop frequencies and calculating a time delay of phase shifting, using equations to generate control signals and reduce circuit loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the operating frequency is increased to achieve low voltage gain or limited output current operation, then the voltage gain requirement is met, but the circuit loss increases beyond converter capacity
Solution Approach 1:
The patent applies parameter changes by simultaneously adjusting two control parameters (frequency and phase-shifting angle) instead of changing only frequency. The mixed controller dynamically modifies both the operating frequency and the phase-shifting angle of the resonant converter, allowing the system to achieve low voltage gain operation without excessively increasing frequency, thereby reducing circuit loss while meeting power requirements.
2Speed
If the pulse width is reduced to lower switching frequency, then the switching frequency decreases, but hard-switching occurs at primary side resulting in large entire loss
Solution Approach 1:
The patent simultaneously adjusts frequency and phase-shifting angle to achieve soft-switching conditions. By coordinating changes in both parameters, the system maintains appropriate pulse widths that prevent hard-switching while keeping switching frequency at optimal levels, thus reducing entire loss compared to methods that only reduce pulse width.
Solution Approach 2:
The mixed controller employs feedback mechanisms to monitor operating conditions and dynamically adjust both frequency and phase-shifting angle to maintain soft-switching. This feedback control ensures that the converter operates in the soft-switching region, preventing hard-switching losses while optimizing switching frequency.
Data Source
AI summary
The present application provides a mixed control method for a resonant converter, a resonant converter system and a mixed controller. When the resonant converter operates in a case where a voltage gain is less than a predetermined value, the method includes: setting a mixed control start frequency, a mixed control stop frequency and a slope of a phase-shifting angle; detecting an operating frequency of the converter; calculating a time delay of phase shifting according to the slope, the mixed control start frequency, the mixed control stop frequency and a resonant frequency of the resonant converter; and according to the time delay, the mixed control start and stop frequencies, generating a control signal to adjust the operating frequency and the phase-shifting angle of the resonant converter. The present application can realize a relatively low voltage gain and a small circuit loss, thereby the circuit efficiency may be improved.