Investigation of transient overvoltages of low voltage induction motors due to IGBT-Inverter supply

The present paper investigates transient overvoltages on ac induction motors when connected through a cable of arbitrary length to IGBT-PWM inverters. Considering classical transmission line analysis, and traveling-wave analysis with zero initial charges on cables, these transient over voltages are about twice the dc link voltage with a short rise time of about 200 ns. Nevertheless for long cables, these transient overvoltages may reach 3 or 4 p.u. The target of the present study is to define the properties of these overvoltages, their dependency on the installation parameters, and to present a combination of two measures (series reactors and capacitor-resistor termination impedance) to reduce the voltage rise du/dt and the over voltages at the motor terminals. Experimental results performed on a 3 kW drive are presented.