Resonant link bidirectional power converter without electrolytic capacitor

A power converter that consists of two identical three-phase pulse-width modulation (PWM) modulators and a novel resonant circuit is presented. The zero-switching-loss PWM power converter and the resonant circuit are presented. The resonant circuit is capable of PWM operation with minimum DC bus voltage stresses and minimum peak resonant current. The new control strategy is integrated to realize a bidirectional power converter without an electrolytic link capacitor. The power flow between converters is bidirectional, and regenerative braking is inherent. The source side currents maintain sinusoidal waveforms with unity power factor. It was observed in the experiment that the resonant circuit guarantees the soft switching of the converter power devices. In addition, by balancing the active power between the source and load side, the voltage across a small ceramic link capacitor can be maintained within a small deviation from the reference. Simulation results and experimental results are presented to verify the operational principles