| 摘要 |
PROBLEM TO BE SOLVED: To increase the efficiency of a system by maximizing the generating section of power loss by a boosting circuit, which boosts DC voltage applied to a motor. SOLUTION: An AC power source 1 is full-wave rectified by an AC/DC switching circuit 2 to obtain a DC voltage, the DC voltage is supplied to an inverter circuit 4 via a boosting circuit 3, and a motor 5 is controlled by conducting PWM control. A control circuit 10 stops the operation of the boosting circuit 3 at starting of the motor 5 and supplies the DC voltage full- wave rectified to the inverter circuit 4, and the rotational speed of the motor 5 is increased by PWM control. If the rotational speed of the motor 5 does not reach the target rotational speed, the operation of the boosting circuit 3 is started when the duty ratio of the PWM control reaches 100%, the output DC voltage of the boosting circuit 3 is increased to a fixed value, and PWM control is conducted again, to thereby control the rotational speed of the motor 5. |
