Abstract
In this paper, we analyze the conditions when surge voltage peaks higher than 2 p. u (2 times the inverter DC link voltage) occur at the induction motor terminals fed by PWM inverters. These overvoltages can reach 3 p. u or more and posse a threat for the motor insulation. Experimental results and simulations are used to study the dependence of voltage at the motor terminals from the application conditions (cable and motor parameters). Anew algorithm for correction of the PWM, which reduce the motor terminal peak voltage under 2 p. u, is proposed and tested successfully in different PWM schemes. Further more a method for calculation of the minimum allowed short time intervals between two consecutive pulses, is given and its results are confirmed from the experiment. Advantages of the new proposed PWM correction method are that it can be implemented at no additional costs, independently from the PWM mode (Sinusoidal PWM, Space Vector PWM, Discrete PWM) used_??_ and without changing the performance of the drive. The application of this method improves the switching reliability of the drive.
