| 摘要 |
PURPOSE:To prevent distortion of the output voltage of a PWM inverter due to short circuit preventing time even near a voltage saturation region, in the PWM inverter used for variable-speed drive of an AC motor. CONSTITUTION:In each phase of a PWM inverter 3, by an output voltage compensating circuit 10, the signal sensed a current polarity sensor 8, which depends on the polarity of the output current of the inverter, is added to the output voltage command issued from an output voltage command circuit 4 of the inverter. When the result thereof exceeds the amplitude of a carrier wave, which is sensed by a carrier wave amplitude sensor 9, the difference between the amplitude of the carrier wave and the original output voltage command is accumulated. Then, the signal corresponding thereto is added to the output voltage command, and the result thereof is outputted to a comparator 7. Thereby, the actual output voltage of the inverter coincides on an average with the original output voltage command, and distortion of the output voltage of the inverter can be compensated even near a voltage saturation region of the inverter. |
