| 摘要 |
PURPOSE:To improve the power factor by a method wherein output voltage of a power converter and speed of a motor are compared, phase difference between voltage and current in AC power source input is detected, and drive signal of the power converter is corrected. CONSTITUTION:To a Graetz connection circuit 4 is inputted three-phase AC power source 1 to which a reactor 2 and a capacitor 3 are connected. After AC-DC conversion, the DC output is supplied to a DC motor 5. A comparator 10 compares output set voltage signal V* with motor rotational speed signal N, and outputs phase difference signal between input voltage and input current. A reference table 11 outputs phase difference correction signal CLS corresponding to the phase difference signal through a limiter 12. The phase difference correction signal CLS corrects drive signal to the Graets connection circuit 4.
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