| 摘要 |
PURPOSE:To suppress the distortion of an output voltage waveform, by arranging a means for detecting the arm voltage of each phase of a main circuit, and a means for subtracting the output of the detecting means, from voltage reference signal turned into the modulated wave of pulse width modulation. CONSTITUTION:So far as the controller of a PWM inverter is concerned, the input of phase U arm voltage on the negative side to a photocoupler 100 via a resistor 90 is provided, and the voltage is taken out of a resistor 11. The input of the arm voltage to a photocoupler 101 and to a photocoupler 102 is provided, and the voltage is taken out of a resistor 13. The arm voltage of each phase taken out in this manner is converted to phase U, phase V, and phase W fundamental-wave component Eu, Ev, Ew, by an arm voltage fundamental-wave component detecting circuit 14, and the input to the negative terminals of adding or subtracting units 150-152 is provided. In the meantime, to the positive terminals, the input of phase U, phase V, and phase W voltage reference signals Eu', Ev', Ew' from a voltage reference signal generating circuit 15 is provided. The output of the adding or subtracting units 150-152 is directed to compensators 160-162 to which the input is provided, and phase U, phase V, and phase W modulated-waves Vu, Vv, Vw for PWM control are generated. |
