Abstract: To eliminate the deficiencies of the conventional drive control system of direct current (DC) motor for electric transit bus, a new permanent magnetic direct current (PMDC) motor with the enhanced exciting windings is designed, namely, enhanced magnetism motor and its drive control system on the basis of the control idea of speed adjusting with field weakening. On the basis of the schematic diagram of motor control system and the test data, the principle of system speed adjusting with field weakening and the working characteristics are analyzed. Compared to the conventional series excitation DC motor, the enhanced magnetism motor has great advantages in respect of control idea, control structure and regenerative braking performance. Heat verification test shows that the IGBT switching loss in high frequency operation has significant influence on the temperature rise of control system. The test result and service test show that the system has strong anti-jamming ability, fast regulating speed and good stability, and the characteristics of enhanced torque with enhancing magnetism at low speed and enhanced speed with weakening magnetism at high speed can meet the electric transit bus’s demand of power characteristics very well.

Key words: Electric transit bus, Enhanced magnetism motor, Peak voltage, Switching loss