| 摘要 |
PURPOSE:To protect a brushless motor when currents simultaneously flow through two phases by providing a 2-phase current detector and interrupting the energization of a drive transistor through a monostable circuit with the signal of the detector, thereby simplifying the circuit. CONSTITUTION:The signals of Hall elements 1-3 which detect the position of a rotor of a brushless motor are applied to a distributor 100 to drive drive transistors 51-53 which sequentially energize a plurality of phase coils AA-CC and to drive the transistors 45-47 of a 2-phase current detector 200. The signal of the detector 200 is applied to a free-running monostable circuit 300, thereby eliminating the reset of the circuit 300, the circuit 300 is maintained by a holder 500 for the prescribed period of time, a signal is produced, thereby interrupting drive transistors 51-53 with an interrupter 600. Accordingly, the motor can be effectively protected when currents flows through the two phases for long period of time, and the influence by the outcoming noise can be reduced by a delay element. |
