Development of Power Converter for Suppression of Harmonic Current

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Various methods have been proposed on circuit technique for suppression of input current harmonics to electronic equipment using switching device. The purposes of this study are as follows, (1) To develop new electronic ballast that can satisfies IEC standard class C for the lighting equipment, and (2) To examine the feasibility of applying developed inverter circuit to general power supply circuit.In the first planning year, the electronic ballast that can satisfy IEC standard by adding charge-pump function to the push-pull inverter circuit has been developed. Charge-pump function is operated using the high frequency voltage that arises at the constant-current inductor in the push-pull circuit. When high frequency voltage is applied in the middle point of two small capacitors that are placed parallel with the input power, two capacitors repeat charge and discharge. As result, the current can flow into the circuit even when the input voltage is low.In the second planning year, the other new electronic ballasts have been developed that can also satisfy IEC standard. A step-down converter and a buck-boost converter for electronic ballast have been developed by improvement of neutral-point-type boost-converter that was proposed by authors. In addition, by analyses of circuit operations of push-pull inverter having charge-pump function, the feasibility of applying this circuit to general power supply circuit was examined. The power supply circuit for several lamps was made, and the experiment is being carried out at present.