The Pwm Plus Phase-shift Control Bidirectional Dc / Dc Converter

Bidirectional DC/DC converters will be widely used in applications such as DC uninterruptible power supplies, aerospace power systems, electric vehicles and advanced mobile generator sets.In order to minimize size and weight of the converters, switching frequency must be increased. But the increase of switching frequency results in higher switching loss. There are many techniques to solve this problem. Some circuits use resonant, quasi-resonant, and/or multi-resonant techniques. However, voltage or current stresses in these converters are higher and require the devices of higher VA rating. Some circuits use passive snubbers or active clamp techniques. However these converters become more complicate. Phase-shift ZVS technique has been used in bidirectional DC/DC converters since it can realize ZVS for all switches without auxiliary switches. However when the amplitude of input voltage is not matched with that of output voltage, the current stresses and RMS currents of the converters become higher, In addition the converters can not achieve ZVS under light-load condition.This paper proposes a PWM plus phase-shift control technique. The PWM control of duty cycles acts as an electric transformer which regulates the amplitudes of equivalent input voltage and equivalent output voltage, so that both positive and negative amplitudes of equivalent input voltage are equal to those of equivalent output voltage. Compared with phase-shift control, PWM plus phase-shift control can reduce the current stresses and RMS currents of the converter. The loss of the converter can also decrease.lt is proved the converter can achieve ZVS in larger load variation.The generations of the PWM plus phase-shift familiy is explained. Taken as an example of the family, the operation principles and analyses of one particular converter are illustrated, respectively. Simulation results and experimental results are also presented.