| 摘要 |
PURPOSE:To detect the locked condition of a rotor, to stop the operation of a motor and to prevent switching elements against destruction, by stopping current supply when the output signal of a position detective means exceeds a certain value. CONSTITUTION:When the power supply is to put to work, a microcomputer 15 begins to output the gate signal of low frequency to switching elements 1-6 and the rotation of a motor beings according to the programme stored in a ROM. The position detective signal is taken in from the comparator of a position detective means 11 and the measurement of changing time beings. When the output signal changes, the measurement of above changing time stops and judges its size. If a changing time is more than a certain length, it is judged as a normal rotating condition. From the output of the position detective means 11 after the change a conducting phase is decided and the gate signal is outputted to switching elements 1-6 and the motor operation continues. If the changing time is shorter than a certain definite time, it is in an oscillating condition and the motor is assumed to be locked, so that the output of the gate signal is stopped and the motor operation is discontinued. |
