An Accurate Approach of Dead-time Compensation for Three-phase DC/AC Inverter

For voltage-source inverters, the dead-time necessary to prevent the shoot-through of the inverter-legs results in output voltage distortion. In this paper, the analysis of voltage distortion is investigated with the consideration of the dead-time and the non-ideal characteristics of the switching devices. From the analysis, an accurate dead-time compensation method is proposed. This method is based on adjusting the pulse width to compensate the switching delay and voltage drop effect of the power devices. Because of the difficulties in current direction detecting around the zero current crossing point, an improved current direction detecting circuit with high precision is presented. By applying this method to a general purpose inverter system, a more accurate output voltage synthesis is obtained with simple logic and flexible implementation. Experimental results verify the effectiveness of the proposed method.