| 摘要 |
PURPOSE: To reduce a noise level and cost of circuit devices by digitalizing a command from an NC apparatus and utilizing a PLL circuit for a control circuit. CONSTITUTION: An apparatus comprises a rectifying circuit 1 to obtain a DC from an AC power supply, a switching element 3 for chopping the DC output, a smoothing circuit 5 for smoothing this output and a control circuit 7 for controlling the switching element 3, etc. The control circuit 7 is composed of a voltage controlled oscillator 9 for converting an output voltage of the smoothing circuit 5 into a pulse of the corresponding frequency, a digital phase comparator 11 for pulling this pulse to the same phase as a command pulse having a duty factor (Ton/T) from an NC apparatus and a drive circuit 13 of the switching element, etc. |
