On the Torques and Losses of Voltage- and Current-Source Inverter Drives

The frequency controlled squirrel-cage induction motor is increasingly applied for variable-speed drives working under extraordinary operational or environmental conditions. Depending on the type of frequency inverter, negative effects like torque ripples and additional losses are different. The torques and losses are calculated for induction machines supplied by the two most frequently used inverter types: the PWM voltage-source inverter and the ASC current-source inverter. For comparison some measurements are presented from test stands with the ratings 45 kW and 25 kW.