| 摘要 |
PROBLEM TO BE SOLVED: To control the rotating speed of a motor over a wide range, by controlling the intermittent operations of the switching element of a booster chopper circuit in a high-speed region and pulse width modulation so that the deviation of the detected speed of the motor from a commanded speed can become zero in a low-speed region. SOLUTION: In a region where a DC voltage is higher than a power supply voltage 21, the DC voltage is controlled by using a booster chopper circuit and an inverter is set to a high-speed control mode. In the other region, the booster chopper circuit controls the DC voltage to a constant voltage, and the inverter is set to a low-speed control mode in which PWM control is performed. The inverter is switched to the high-speed mode from the low-speed mode when the PWM control duty of the inverter becomes 100% and to the low-speed mode from the high-speed mode when the DC voltage becomes lower than a set voltage. Therefore, the speed of a motor can be controlled over a wide range. |
