| 摘要 |
PURPOSE:To prevent the effects of rectification ripplies and to reduce the capacity of filters by varying the pulse width of the PWM signal of a pulse-width modulation type inverter depending on the signal of a detector circuit which detects a DC input voltage. CONSTITUTION:The output of a rectifier 1 is applied to a PWM inverter 4 wherein GTO is employed via filters 2 and 3, and an induction motor 5 is driven by the output thereof. The output of a frequency command circuit 6 and the output of an oscillator 7 are multiplied in a multiplier 8, and the result is given to a comparator 11. The DC input voltage to the invrter 4 is detected by a detector 13, and multiplied by the output from a triangular wave generator 9 in a multiplier 10, and the result is given to the comparator 11. The output thereof controls the on and off of the GTO of the inverter 4. Since the variation in the DC input voltage which will appear in the output voltage can be cancelled, the capacity of the filters can be reduced and the configuration of the device can be made small. |
