Patent ID: 9641109
Date: 2017-05-02
CPC Classifications: H02K,H02P

Claim:
1. A brushless DC motor drive circuit comprising: a drive coil positioned in a magnetic field of permanent magnets provided in a rotor; a direct current power source supplying drive power to the drive coil; a first transistor that is emitter-grounded, in which a collector is connected to the drive coil; a second transistor that is emitter-grounded, in which a collector is connected to a base of the first transistor; a base current controlling resistor adjusting a base current of the second transistor; a detecting coil positioned in a magnetic field of the permanent magnets and provided between a base and an emitter of the second transistor; and a diode connected between the base and emitter of the second transistor in series with the detecting coil and provided in a forward direction running parallel to a current between the base and emitter of the second transistor, wherein the diode controls and adjusts the base current of the second transistor such that the second transistor is turned on when a reverse voltage is applied by induced electromotive force generated in the detecting coil and such that the second transistor is turned off when a forward voltage is applied by the induced electromotive force of the detecting coil.