High frequency modeling and analysis of voltage reflection in the three-level PWM inverter-fed high power induction motor drive system

In the pulse-width modulated (PWM) inverter-fed motor drive system, the rapidly changing voltage resulting from high frequency switching operation of IGBTs can create severe insulation problems for an induction motor. Presently, the research of the PWM pulse voltage reflection is basically based on the two-level inverter and the induction motor that the rated power is less than 200kW. This paper investigated the voltage reflection in the three-level inverter-fed motor drive system and a restraint strategy of the voltage reflection is proposed. The simulation study and experiment result show that, the simulation and the experiment result matched well and the reflection of the traveling voltage wave at the cable end was greatly restrained.