Three-phase windings 11-13 and 21-23 of a first common-mode transformer 1 and a second common-mode transformer 2 are connected in series through connecting lines 8r-8t, respectively. The windings 11-13 are connected to an unillustrated AC power supply by connecting lines 91r-91t. The windings 21-23 are connected to a three-phase motor by connecting lines 93r-93t and through a converter and an inverter which are unillustrated. A winding 14 for common-mode voltage detection detects high-frequency leakage currents flowing through the connecting lines 91r-91t as a common-mode voltage V1, and an output voltage V2 obtained by voltage amplification by a voltage amplifier 3 is applied to a winding 24 for common-mode voltage application in such a manner that the output voltage V2 works in generally the same direction as the common-mode voltage V1, thereby canceling out the high-frequency leakage currents through the windings 21-23. Since a voltage amplification method is used, it is possible to reduce the high-frequency leakage currents with a simpler configuration as compared to a conventional current amplification method.

Leakage current reduction apparatus
Application Number
Publication Number
Application Date
March 4, 2010
Publication Date
December 29, 2011
Takuya Sakai
Satoshi Azuma
Mitsubishi Electric Corporation
H02M 07/04
H02M 07/44
H02M 05/45
H02M 01/00
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