| 摘要 |
PURPOSE:To restrain harmonics components of current effectively by a method wherein a power rectifying unit is constituted of a self arcextinguishing element while the switching element of the power rectifying unit is controlled through PWM control. CONSTITUTION:A power rectifying unit 6 converts an AC power from an AC power source 1 into a DC power. The DC power of the power rectifying unit 6 is converted into the AC power of a predetermined frequency by a power inverting unit 10 and, thereafter, is supplied to an induction motor 19a. A control circuit unit 17 inputs a synchronous signal S1, a load current detecting signal S2, an inverter current detecting signal S3, a DC voltage detecting signal S4 and a DC current detecting signal S5 and outputs PWM signals based on these signals to control the transistor 7 of the power rectifying unit 6. According to this method, harmonics can be restrained effectively. |
