A direct compensation scheme of the dead-time effect in PWM-VSI

This paper presents a direct compensation of the switching interval error by the dead-time of a PWM-VSI(Voltage Source Inerter) drives. The output voltages of the 3-phase VSI are distorted and have error by the dead-time to avoid the shoot-through of an inverter arms and the time delay of the gate drive. The voltage distortion increases a harmonic component of the output voltage and decreases the control performance. This paper presents a simple and cost-effective compensation technique to solve this problem in the 3-phase voltage source inverter using the direct switching interval compensation. The practical switching voltage interval of an inverter has error with the PWM signal of the controller due to the dead-time and the time delay of the gate drive. And this error is dependent on the current direction and makes an additional output voltage distortion. This paper analyzes the switching voltage interval error of the 3-phase voltage source inverter according to the current direction. And the compensated switching times are added to the PWM interval of the controller to compensate the output voltage distortion. With a simple detection of the current direction, the practical error of the switching interval can be compensated by the adding of the compensated switching time. Simulation and experimental results validating the proposed compensation method are presented in this paper.