Pulse based dead time compensator for PWM voltage inverters

Abstract

The dead time necessary to prevent the short circuit of the power supply in pulse width modulated (PWM) voltage inverters for AC drives results in output voltage deviations. Although individually small, when accumulated over an operating cycle, the voltage deviations are sufficient to distort the applied PWM signal. This paper presents a new method to correct for the dead time deviations. The pulse based compensator is less hardware and software intensive than other dead time compensation methods providing a low cost solution. The pulse based technique is developed by analyzing the effects of dead time on a pulse by pulse basis and correcting each pulse accordingly. The technique is evaluated through simulation and experimental results. Other compensation methods are evaluated and the results compared with the pulse based technique. This comparison indicates previous methods can produce magnitude and phase errors in the applied terminal voltage, whereas the proposed method compensates for the dead time without significant magnitude and phase errors in the terminal voltage of PWM voltage source inverters.