Analysis of the Effect of the Parasitic Capacitance of Switch Devices on Current Distortions of Voltage Source Rectifier

Deadtime produces current distortion in voltage source PWM converters, especially for high switching frequency PWM converters. The deadtime voltage error considering the effect of parasitic capacitance of switch devices is analyzed. The fast Fourier transform (FFT) of deadtime voltage error within a line frequency period is given. The (6n±1)th harmonic spectrums of the deadtime voltage error with different parasitic capacitances are shown. As parasitic capacitance increases, the (6n±1)th harmonics of the deadtime voltage error decreases, thus the current harmonics of three-phase voltage source rectifier (VSR) decreases. Simulation results of the MATLAB/SIMULINK model are given to verify the theoretical analysis of the effect of parasitic capacitance on current distortions of three-phase VSR.

I. Introduction

Voltage source PWM converters have been widely used in active power factor correction (APFC), renewable power generation systems, motor drive systems, and so on. In the voltage source PWM converters, deadtime between two switches in the same leg is usually designed, which brings voltage losses, reduction of dc-link voltage utilization, and high voltage/current harmonics. The switching frequency of voltage source PWM converters tends to become higher to miniaturize the volume and to improve the performance [1]–[3]. With the increase of switching frequency, the deadtime effect becomes remarkable [4].