| 摘要 |
PROBLEM TO BE SOLVED: To detect an input current without use of a direct current detector when a rectifier circuit is operated with a high power factor. SOLUTION: Resistors 11 and 12 are connected in serial with both semiconductor switch circuits, and a first current computing circuit 20 computes the input current IIN of the rectifier circuit from the voltages of both resistors 11 and 12. The first current computing circuit 20 is composed of a first adder 25 which subtracts a negative voltage detection value from a second negative voltage detector 24 connected with the second resistor from a negative voltage detection value from a first negative voltage detector 23 connected with the first resistor 11. Alternatively, an alternating current detector 31 is installed on the input side of the rectifying circuit, and the resistors 11 and 12 are connected in series with both the semiconductor switch circuits. A second current computing circuit 30 computes the input current IIN of the rectifier circuit from the voltages of both resistors 11 and 12 and a detection value from the alternating current detector 31. The second current computing circuit 30 is composed of a second adder 32 which subtracts the voltage of the second resistor 12 from the voltage of the first resistor 11; an average value computing unit 33 which determines the average value of the results of the computation by the second adder; and a third adder 34 which adds the computed average value and the detection value from the alternating current detector 31. COPYRIGHT: (C)2004,JPO
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