| 摘要 |
The purpose of the present invention is to easily and accurately estimate the power consumed by a load, without detecting the input voltage from an AC power supply. A control circuit (20), in accordance with an input current, determines whether a drive pulse for opening and closing a switching member (16) is to be on or off, doing so in such a way that when the input voltage from the AC power supply (11) is constant, the DC voltage supplied to the load at a prescribed input current is constant. Then, on the basis of the input current and the DC voltage, the control circuit (20) estimates the input voltage, and calculates the power consumed by the load (15) from the input voltage, the input current, and the power factor. |
