Voltage stress on induction motors in medium voltage (2300 to 6900 V) PWM GTO CSI drives

This paper deals with voltage stress on induction motors in medium voltage PWM GTO current source inverter drives. The voltage stress on the motor in this transformerless drive is investigated. Analytical equations are derived for the calculation of the maximum peak line-to-ground voltage applied to the motor. It is demonstrated in the paper that this peak line-to-ground voltage could be twice as high as the rated peak line-to-neutral voltage of the motor. Computer simulation and experimental results on a 4160 V, 1250 hp induction motor drive are given for the verification of theoretical analysis. This paper provides a valuable design guidance for the insulation of medium voltage motors used in this type of drives.<
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