Abstract: Research on electrically excited synchronous motor(ESM) based on direct torque control(DTC) in China at present is still a vacancy. Damper windings mounted in the rotor of ESM affect the dynamic performance of motor inevitably. In this paper the relationship between torque and torque angle in ESM of DTC is firstly deduced detailedly, and then the effects of damper windings on the dynamic performance of ESM based on DTC are presented by digital simulation. The results of simulation show that the derivative of the main torque near the zero cross is positive with respect to the main torque angle. The q-axis damper winding can reduce the oscillation amplitude of the torque and speed significantly, and the d-axis damper winding improves the dynamic performance of the motor slightly and decreases the system's stability. So the d-axis damper winding is unnecessary.

Key words: motor, electrically excited synchronous motor, direct torque control, damper windings, dynamic performance