Soft-switching inverter based on variable-frequency control of absorber power device

A resonant DC link soft-switching inverter is composed of resonant DC converter and full-bridge inverter. The resonant DC link outputs a DC pulse voltage, thus providing zero-voltage-switching condition for power devices in inverter bridge. Compared with the hard-switching inverter, the current pulsation of output filter inductor and the voltage stress of power devices in the inverter bridge are raised because of the DC pulse voltage. For this reason, this paper proposes a variable-frequency control strategy of absorber power device for forward DC link soft-switching inverter. The control logic is given. The operational modes of inverter are analyzed and experimental results are presented. Performance contrasts under constant-frequency and variable-frequency control of absorber power device are analyzed by simulation. This control strategy is beneficial for reducing the voltage stress of power devices in inverter bridge and improving the efficiency of inverter. The power devices realize zero-voltage-switching as before.