| 摘要 |
PURPOSE: To suppress the flowing harmonic currents of a power converter for AC electric vehicles in its overhead wire, by connecting the terminals of the secondary winding of its main transformer by a plurality of parallel LC filters whose resonance frequencies are integral times as high as the double frequency of its switching frequency. CONSTITUTION: The terminals of a secondary winding 2-2 of a main transformer 2 of a power converter for AC electric vehicles are connected by a three-level PWM converter 4 to convert an AC voltage into a DC voltage. The DC side output of the converter 4 is connected with a three-level PWM inverter via filter capacitors 5, 6, and the VVVF-controlled AC output thereof is connected with a three-phase induction motor 8 to drive an electric vehicle. Also, while the terminals of the secondary winding 2-2 are connected by parallel LC filters 21, 22, 23 since the remarkably appearing frequencies of the flowing harmonic currents of the three-level PWM converter 4 in the overhead wire of the power converter are integral times as high as the double frequency of its switching frequency, the resonance frequencies of the LC filters 21, 22, 23 are made respectively to be two, four and six times as high as its switching frequency. As a result, the flowing harmonic currents in the overhead wire can be suppressed, and their inductive interferences can be reduced. |
