| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply unit which can suppress rush currents, using a simple configuration. SOLUTION: The power supply unit includes a rectifying circuit 2 for rectifying a commercial AC power source 1, a smoothing capacitor 3 for smoothing the rectified voltage of the rectifying circuit 2, a switching element 4 connected in series to the smoothing capacitor 3, a zero-cross detection circuit 5 which detects whether the rectified voltage is lowered than a specified value after the commercial AC power source 1 is connected, and a switch drive circuit 6 which maintains the off-state of the switch element 4, when the zero-cross detection circuit 5 detects a rectified voltage which is larger than the specified value, and turns on the switching element 4, to connect the rectifying circuit 2 with the smoothing capacitor 3, when the zero-cross detector circuit 5 detects the rectified voltage which is smaller than the specified value. COPYRIGHT: (C)2008,JPO&INPIT
|
