| 摘要 |
PROBLEM TO BE SOLVED: To simplify the control circuit of an AC-DC converter, to enhance its efficiency and to reduce its noise. SOLUTION: In the AC-DC converter, positive side power converter IGBTs 4, 6, 8 and negative side power converter IGBTs 5, 7, 9 in a switching circuit 3 are simultaneously controlled ON, OFF as pairs. Thus, the control sequence of the switching operations of the respective IGBTs 4 to 9 is simplified, and the constitution of the control circuit 21 can be simplified. After the voltage between the collector and the emitter terminals of the respective IGBTs 4 to 9 is lowered to substantially 0 V by a zero voltage circuit 48, the respective IGBTs 4 to 9 are switched to ON. Thus, when the IGBTs 4 to 9 are turned ON, the IGBTs 4 to 9 are zero voltage switched. Thus, the switching losses in the IGBTs 4 to 9 are reduced, and the converting efficiency of the each IGBT can be improved, and a switching noise can be suppressed.
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