Power converter

[0023]FIG. 1 is a circuit diagram of a power converter 1 according to Embodiment 1. As illustrated in FIG. 1, power converter 1 includes a diode rectifier 110, a smoothing capacitor 120, an inverter 130, a bypass circuit 175, a detector 180, and a controller 190. Bypass circuit 175 includes a bidirectional switch 160 and a Y capacitor 170. Controller 190 includes a comparator 192 and a drive unit 193.

[0024]Diode rectifier 110 rectifies an AC voltage output from a neutral-grounding three-phase AC power supply 100 to a DC voltage and outputs the DC voltage to DC buses ML1 and ML2.

[0025]Smoothing capacitor 120 smoothes the DC voltage rectified by diode rectifier 110.

[0026]Inverter 130 converts the DC voltage smoothed by smoothing capacitor 120 into a desired AC voltage, and drives an electric motor 140.

[0027]Bidirectional switch 160 and Y capacitor 170 are connected in series between one end of smoothing capacitor 120 and the ground. Y capacitor 170 reduces a high-frequency common-mode...

[0040]FIG. 3 is a circuit diagram of a power converter 2 according to Embodiment 2.

[0041]As illustrated in FIG. 3, power converter 2 includes a diode rectifier 210, a smoothing capacitor 220, an inverter 230, an electric motor 240, a bypass circuit 275, a detector 280, and a controller 290. Bypass circuit 275 includes a bidirectional switch 260 and a Y capacitor 270. Controller 290 includes a computing unit (filter) 292, a computing unit (absolute value) 293, a computing unit (peak value) 294, a comparator 295, and a drive unit 296.

[0042]Diode rectifier 210 rectifies an AC voltage output from a neutral-grounding three-phase AC power supply 200 to a DC voltage and outputs the DC voltage to DC buses ML1 and ML2.

[0043]Smoothing capacitor 220 smoothes the DC voltage rectified by diode rectifier 210.

[0044]Inverter 230 converts the DC voltage smoothed by smoothing capacitor 220 into a desired AC voltage and drives electric motor 240.

[0045]Bidirectional switch 260 and Y capacitor 270 are c...

[0063]FIG. 4 is a circuit diagram of a power converter 3 according to Embodiment 3. As illustrated in FIG. 4, power converter 3 includes a diode rectifier 310, a smoothing capacitor 320, an inverter 330, a bypass circuit 375, and a controller 390. Bypass circuit 375 includes a bidirectional switch 360 and a Y capacitor 370. Controller 390 includes a comparator 392 and a drive unit 393.

[0064]Diode rectifier 310 rectifies an AC voltage output from a neutral-grounding three-phase AC power supply 300 into a DC voltage and outputs the DC voltage to DC buses ML1 and ML2.

[0065]Smoothing capacitor 320 smoothes the DC voltage rectified by diode rectifier 310.

[0066]Inverter 330 converts the DC voltage smoothed by smoothing capacitor 320 into a desired AC voltage and drives electric motor 340.

[0067]Bidirectional switch 360 and Y capacitor 370 are connected in series between one end of smoothing capacitor 320 and the ground. Y capacitor 370 reduces the noise caused by switching of a switching e...