Quasi-resonant DC-link voltage inverter with enhanced zero-voltage switching control

A new topology modification of the parallel quasi-resonant circuit for a dc-link voltage inverter enables regulation of the zero voltage dc-link subperiods and the dc-link voltage gradient settings. The proposed circuit is based on four MOSFET switches with free-wheeling diodes for controlled quasi-resonant recharging between L-C tank in order to assure inverter zero voltage switching (ZVS) conditions. Design optimization of the prototype quasi-resonant inverter and timing sequences for common mode voltage reduction are described. Preliminary experimental results confirm precise controllability of the inverter ZVS operation.