A novel method for suppression of high voltage gradient transient effects in voltage-fed PWM inverter

This paper presents a design consideration for the effects of long feeding cable in adjustable speed drive (ASD). The influence is mainly the overvoltage transient presented in the induction motor. Causes contributing to the motor transient overvoltage including typically <2 pu (per unit) bus voltage or especially >2 pu case have been highlighted clearly both by theory and experiments. Traditional passive filter techniques have also been reviewed, and a novel simple filtering structure with low power loss has been proposed. A case study for an adjustable speed high-power AC motor drive is demonstrated by means of prototype experiment to prove its performance and effectiveness.