Damped input filter design of matrix converter

This paper deals with the input filter design of matrix converter. Regard the matrix converter as a buck type PWM rectifier in the input side, the transfer function of input current using LC input filter is deduced. The parameter selection approach for the capacitor and inductor is presented. It has been verified that when LC circuit is adopted in the input filter, the input current will oscillate near the LC resonant frequency in both steady state and start-up process for the very low damping factor, and then the input current waveforms will be distorted. An improved input filter topology to increase the damping factor is then presented, and the damping resistance parameter selection method of the input filter is presented based on frequency response approach. To avoid the current spike at the start-up process, a start-up circuit is then proposed. The improved input filter has been tested on a 5.5 kW matrix converter prototype and good performances are achieved.