CONTROLLING APPARATUS FOR A D.C. BRUSHLESS MOTOR

摘要

A brushless D.C. motor is supplied an A.C. voltage from a polyphase thyristor bridge inverter which functions as a static commutator. A controllable rectifier is provided for supplying a D.C. voltage to the inverter. There is also provided a starting control circuit which causes the rectifier to act as an inverter during every commutation of the thyristor bridge inverter, rapidly turning off the thyristors in the inverter. The starting control device also functions to cause the commutator lead angle of the thyristor bridge inverter to remain substantially zero while the rotational speed of the motor is less than a predetermined value. Thus, it is possible to excite the armature winding of the motor with the maximum rated voltage to derive the maximum torque therefrom.