An Improved Method of Dead Time Compensation in the Zero-crossing Current Region with Low-Frequency Operation

In a voltage-fed PWM inverter, the relation between the reference voltage and actual output voltage is nonlinear due to the dead time effect and the voltage drop of power devices. The distortion of voltage invokes serious problems such as current waveform distortion and deterioration of the systems. More seriously, the current waveform is clamped to be a wide platform around the zero crossing point in the low-frequency region. In this paper, an improved method which reduces the distortion of voltage and current is presented. The method is based on SVPWM strategy and it can be implemented with software without any extra hardware. Simulation results are presented to demonstrate the validity of the proposed method.