| 摘要 |
PURPOSE:To enable the operation of a motor in the maximum efficiency and to eliminate the efficiency decrease of an inverter even if a load and an input voltage are altered by controlling a DC/AC converter so that the output AC voltage becomes approx. 1-1.2 times of the minimized DC voltage. CONSTITUTION:To detect a DC current output from a converter 10, a resistor 20 is provided to the output terminal of a converter 10. An average DC current value detector 22 is provided across the resistor 20 to detect the average value of the DC current. The average DC current value signal from the detector 22 is input to a DC current minimized voltage detector 24. The detector 24 detects the voltage that the DC current becomes minimum when the frequency of the output AC power is constant and the voltage is varied, and outputs the optimum set voltage. |
