Driving circuit for brushless D.C. motor

摘要

A driving circuit for a brushless motor having a permanent-magnetic rotor is disclosed which is capable of positively carrying out starting of the motor and rapidly interrupting exciting current to protect the motor, when the rotor fails to rotate during the normal operation. The driving circuit includes transistor control circuits each including a capacitor, a PUT, and a capacitor charging circuit comprising a Zener diode and a resistor; and a resistor series circuit for flowing conductive signal current to a transistor switch which serves to supply current to exciting windings. The PUT is conductive to allow the transistor switch to be kept non-conductive when the capacitor is charged to a predetermined voltage.