Abstract
This paper describes commutation characteristics of snubber circuits of the PWM rectifier for the converter without DC link components. The DC link part of this converter has no smoothing circuit such as electrolytic capacitors and reactors. Therefore, one of the switches in the upper arms and one of the switches in the lower arms of the rectifier must be on-state in order to assure the path of the load current. The rectifier section of this converter requires the LC filter to improve the AC source current waveforms. Consequently, dead time should be applied to each of the commutation switches to prevent short circuit through the filter capacitors. The currents of the load are kept through the snubber circuit during the dead-time period. In this paper, we discuss an analytical method of the converter with the snubber circuit of the rectifier, and the experimental results are used to verify the analytical method. Next, the optimal snubber parameters are determined by calculation for 0.75kW induction motor driven by this converter. Finally, suitable snubber circuits for bidirectional switches are discussed.
