DC pre-excitation application in three-phase induction motor drive system

Due to the current restriction of semiconductor devices, the start-up is an extremely important process in the ASD (adjustable speed drive) system. DC pre-excitation is one of the effective solutions for increasing the starting torque and depressing the starting inrush current. However the effect of DC pre-excitation would be discounted if it could not be compatible with the induction motor drive control system. Also the stability of the DC pre-excitation application is related to its operational mode. This paper addresses the principle of DC pre-excitation and excavates its relationship with current control. The method to improve the stability of DC pre-excitation effectively shielding EMI is detailed. The relevant study has been implemented in a control system for a 55 kW and 160 kW induction motor and the simulation and experimental results validate the effectiveness of the proposed design method.