Efficient technique for suppression of motor transient voltage

This paper presents a design consideration for the effects of long feeding cables in pulsewidth modulation (PWM) voltage-fed drive. The focus is mainly the overvoltage transient presented in the motor. Theoretical analysis has been achieved based on the transmission line traveling wave theory. Factors contributing to the motor transient overvoltage including typically < 2 pu (per unit) bus voltage or especially the > 2 pu case are described both in theory and by experiment. An improved simple filter structure with low power loss has been proposed. Case study for an adjustable speed ac motor drive is demonstrated by means of prototype experiment to prove its performance and effectiveness.