| 摘要 |
PURPOSE:To enable the optimum voltage operation suppressing the hunting of output voltage by means of a compressor pulsating load by controlling the voltage of an AC power supply through data obtained by storing and equalizing the latest plurality of times of each time voltage-current phase difference data of an induction motor for driving the pulsating load of a compressor. CONSTITUTION:Each time output of a phase difference detection circuit 30 is successively stored in a phase difference data storage circuit 40 with shift register function for latest N times. Then, when N data are shifted, phase difference data are equalized by a phase difference data equalization circuit 50. A voltage control means 60 determines whether the equalized phase difference data is larger or smaller than a phase difference reference, and sends a voltage correction command to a DC/AC converter 10 so that a voltage is lowered when a mean value is larger than a reference value and the voltage is raised when the mean value is smaller than the reference value. Thus, it is possible to suppress the hunting of output voltage. |
