| 摘要 |
PROBLEM TO BE SOLVED: To contrive downsizing, price reduction and reliability enhancing of the device which can dissolve the errors in detection of input current in continuous operation mode with one piece of current transformer for the detection of input current detection. SOLUTION: This device is provided with a boosting chopper and a control circuit (power factor active filter circuit) 2 for improving the power factor. A current transformer CT is provided with a pair of primary windings Np1 and Np2 and a pair of secondary windings Ns1 and Ns2 in a single core 1, and causes the current flowing into a choke L for chopper at on and off states of an inverter element SW to flow alternately to the primary windings Np1 and Np2. An input current detecting circuit 3 causes a detection current to flow alternately into a current detection resistor R by the secondary voltage induced reversely in the secondary windings Ns1 and Ns2 in a pair of the current transformer CT, accompanying the turning on and off of the inverter element SW, and outputs a detection voltage proportional to the input current.
|
