| 摘要 |
PURPOSE:To save the energy consumption of a motor and to reduce noises by controlling the rotation of a DC motor driven by a power steering pump by means of a chopper so as to lower is when driving straight and to raise it when steering. CONSTITUTION:When a hand brake is released, a switch 5 is turned on and an excitation coil 4 is excited to turn a solenoid contactor 2 on. At the same time, a conduction ratio control unit 11 outputs a command to chop a chopper 8 at a low conduction ratio to the chopper 8, thus a DC motor 3 is operated at a low speed. When a steering operation is performed, the current flowing through the DC motor 3 is increased, and a value corresponding to the current detected by a shunt resistor 10 is amplified by a current amplifier 12, then a signal is output from a current comparator 13 to the conduction ratio control unit 11 so that the conduction ratio of the chopper 8 is made high. As a result, the DC motor 3 is operated at a high speed. |
