Constant voltage and frequency type PWM inverter with minimum output distortion

摘要

Imprementation is presented with a view to eliminating waveform distortion in an ac power supply device using a voltage type inverter. To realize this, there is provided a control system to detect a current flowing through a capacitor for absorbing higher harmonics provided along with a smoothing reactor between the voltage type inverter and a load to compare the current detector with a sine wave reference to control the voltage type inverter by making use of the compared result. To this control system, a correction control system for follow-up control of the output voltage of the ac power supply device may be added. The correction control system is configured to detect an output voltage of the ac power supply device which lags the capacitor current by a phase angle of 90 degrees to compare the output voltage detected with another sine wave which lags the sine wave reference by a phase angle of 90 degrees to use the compared result as a voltage control signal.