Hybrid PWM Control of Bidirectional DC/DC Resonant Converter for Low-Current-Ripple and Wide-Voltage-Gain Application

To accommodate to the application where both low current ripple and wide voltage gain are required, a hybrid pulse width modulation control strategy for a modified isolated bidirectional DC/DC resonant converter is proposed. Unlike the conventional variable frequency control, the switching frequency is fixed to be the resonant frequency, facilitating the optimized design of magnetic components. Instead, to attain the required voltage gain, PWM control of both high-voltage-side and low-voltage-side switches is employed but not simultaneously. The proposed control strategy achieves zero voltage switching of all the switches, extends the voltage gain, and limits the current ripple, which improves the converter and broadens its application. A 1000W/400V output prototype was built in the lab to verify the theoretical analysis.