Comparative Study of Vector Control Schemes for Parallel-Connected Induction Motors

The field-oriented control is primarily used in single inverter single motor drive system, but in railway traction drive system one inverter feeds two or more motors connected in parallel. The purpose of this paper is to make comparative study between different control schemes for the parallel-connected motor drive system by simulation and experiment. First the rotor flux orientation control system for single motor is established on simulation platform and then the control system extends to the multiple motor drive systems by using the averaging model of the parallel-connected motors. The two ways of averaging, namely circuit averaging and space vector averaging, are either based on the steady state equivalent circuit of the induction motors or on the voltage space vector reference. The simulation is based on Saber simulation software and the simulation results and experimental are given to show the effectiveness of the control schemes proposed in the paper