Dead-time effect and its compensation in common-mode voltage elimination of PWM inverter with auxiliary inverter

This paper discusses improvement of common-mode voltage elimination ability of a PWM inverter with an auxiliary inverter. The main inverter and the small capacity auxiliary inverter are connected at the neutral point of the LC filter. The auxiliary inverter compensates common-mode voltages of the main inverter. Additionally, because the auxiliary inverter does not output active power, the capacity of the inverter is small. Common-mode voltages results from rapid change of output voltage when the switching is done in inverter. The common-mode currents flow through parasitic capacitances. Theoretically, the auxiliary inverter is able to perfectly compensate the common-mode voltage generated by the main inverter. Actually, however, the common-mode voltage appeared by the dead-time effect. This paper presents the influence of the dead time to the common-mode voltage of the PWM inverter with the auxiliary inverter and its compensation.