| 摘要 |
PURPOSE:To detect an abnormality such as short circuits in a DC motor positively even during the revolution of the DC motor. CONSTITUTION:A PWM signal is supplied into a DC MOTOR M from a PWM control means S1. A driving current for a DC motor is controlled at the value within the specified range with a specified reference current as the center in response to the duty ratio. During this period, a terminal voltage, which is applied to the DC motor, is operated at from the duty ratio of a power supply voltage and the PWM signal with a terminal voltage detecting means S2. The number of revolution of the DC motor is detected with a number-of-revolution detecting means S3. The driving current, which is actually supplied into the DC motor, is detected with a current detecting means S4. In a reference-current setting means S5, a reference current is set in response to at least the terminal voltage and the number of revolution. In a motor-abnormality judging means S6, whether the difference exceeding the specified value has occurred between the actual driving current of the DC motor and the reference current or not is judged. When the difference exceeding the specified value has occurred, it is judged that the DC motor is abnormal. |
