CLLLC谐振变换器电流应力抑制策略OA

Under over-resonant operating conditions,a CLLLC resonant converter with frequency modulation control will generate excessive current stress.On the basis,a control strategy based on phase-shift frequency modulation is proposed to suppress the current stress.A resonant current model under phase-shift frequency modulation control is established by the first harmonic approximation method.According to the soft switching condition and transmission power characteristics of the converter,the phase-shift values on the primary and secondary sides of the isolation transformer are obtained.Combined with the switching frequency obtained by frequency modulation control,the resonant current stress is reduced.Finally,a circuit simulation model and an experimental system of the CLLLC resonant converter were built to verify the analytical conclusions,and results show that the proposed strategy has a significant inhibitory effect on current stress.