| 摘要 |
PURPOSE:To enable to reduce the size of a smoothing choke coil by connecting a switching element which is controlled ON or OFF with a signal of a voltage controller between a rectifier and an inverter and controlling the DC input of the inverter. CONSTITUTION:A switching element 17 is inserted between a rectifier 1 which employs diodes 8 and an inverter 2 which is controlled by a frequency controller 3, and turned ON or OFF by a voltage controller 4 which has sawtooth wave oscillating means 19 and control means 20 for varying the duty cycle by converting the sawtooth wave of the means 19 to a rectangular wave, thereby driving an induction motor M. Accordingly, the DC voltage from the rectifier 1 can be regulated by the ON or OFF of the element 17, the smoothing choke coil 7 can be reduced in size by selecting the frequency to a higher value, and the reduction in the cost of the rectifier 1 and the improvement of the entire efficiency can be performed. |
