| 摘要 |
PROBLEM TO BE SOLVED: To maintain a driving current flowing in a contactor to be proper and eliminate energy loss, heat generation, etc., by detecting the voltage of a battery and controlling the driving voltage of the contactor on the basis of the detected voltage value to be constant. SOLUTION: The terminal voltage VB of a battery 1 is detected with a battery voltage detecting circuit 3. The duty ratio of current flowing time of an electromagnetic coil 7 is calculated with a duty ratio operating circuit 4, on the basis of the detected battery terminal voltage VB, and a PWM(pluse width modulation) signal S1 of the duty ratio is generated. The generated PWM signal S1 is applied to the base of a transistor 20 of a contactor coil driving circuit 5, and the transistor 20 is operated. A driving signal S2 which makes a current flow in the electromagnetic coil 7 of a contactor 6 only during a period that an ON signal is generated by the PWM signal S1 is outputted to the contactor 6, and the driving voltage of the contactor 6 is controlled to be constant. |
