| 摘要 |
PROBLEM TO BE SOLVED: To obtain a noise reduction circuit which is small and low-cost by a method, wherein it can cope even with a case in which the DC power supply of a transformer is grounded to a neutral point. SOLUTION: A rectifier 12 is connected, via an insulating transformer 12, to the DC side of a rectifying circuit 2 so as to supply electric power to a capacitor C2 and a capacitor C3. The connecting point of the capacitors C2, C3 is connected to the neutral point of a capacitor C4 and a capacitor C5. In addition, a transistor Tr1 and a transistor Tr2 are connected in parallel with the capacitors C2, C3. A coupling capacitor C1 is connected to the connecting point of the transistors Tr1, Tr2. When a leakage current flows to the grounding line of a DC power supply 4 from a load 6, the transistor Tr2 is turned on, a noise compensation current is made to flow to the input line of an inverter circuit 5 through the transistor Tr2 and the capacitor C3 from the coupling capacitor C1, and the leakage current which flows to the grounding terminal of the DC power supply 4 through the grounding line is offset. |
