| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a load drive unit high in power factor and high in efficiency in a wide input range. <P>SOLUTION: The load drive unit is provided with a first voltage control means that is composed of a reactor 2 connected in series to an AC power supply 1, a first rectifying circuit 3 and a switching element 4, and generates boosting voltages at both ends of a series circuit composed of the first rectifying circuit and the switching element; second voltage control means 5, 7 that rectify and smooth outputs of the first voltage control means; and an operation control means 10 that comprises a load drive circuit 9 that converts outputs of the second voltage control means to AC voltages and PWM-drives a load, a zero-cross detection circuit 13, an input current detection circuit 17 and a DC voltage detection circuit 16 of the second voltage control means, and generates a drive signal that drives the switching element 4 on the basis of detected outputs of the input current detection circuit 17 and the DC voltage detection circuit 16. The load drive unit limits an on-period of the switching element within a limit value that corresponds to the input current detected by the input current detection circuit 17. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
