Analysis of the effect of feeder cable on the stator winding voltage stress in a PWM induction motor drive

In this paper, the effect of feeder cable on the nonlinear voltage distribution among the stator windings of a PWM inverter fed induction motor is discussed. The feeder cable-induction motor model is developed in ATP, the PC version of EMTP to simulate the nonlinear voltage distribution among the turns and coils of the motor windings during PWM wave fronts. The high frequency equivalent circuit parameters of the cable are calculated using the Cable Constants routine in ATP and those of the motor are computed using finite element analysis. The model developed can be used to simulate the various types and configurations of cables, the effects of rise-time of the wave front, and terminal filters on the voltage distribution. Simulation results obtained show that though the terminal voltage doubles during the switching transient, the voltage distribution among the turns of the line end coil does not change appreciably with the introduction of feeder cable between the inverter and the motor