JP2677022B2 - AC electric vehicle power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for an AC electric vehicle having an inverter and a plurality of converters.

[0002]

2. Description of the Related Art FIG. 3 shows, for example, JP-A-63-302702.
2 is a diagram showing a main circuit configuration of a control device for a conventional alternating-current electric vehicle disclosed in Japanese Patent Publication No. In the figure, 1 is an AC overhead wire, 2 is a pantograph, 3 is a main transformer, 4 and 5 are PWM
Control converter (hereinafter referred to as PWM converter),
4a and 5a are positive output terminals of the intermediate DC circuit of the PWM converters 4 and 5, 6 is a smoothing capacitor of the intermediate DC circuit, 7 is a variable voltage variable frequency inverter (VVVF inverter), 8 is an induction motor, and 9 is a charging resistor. Reference numeral 10 is a short-circuit switch that is opened at startup, 11 is a switch that is opened at startup, and 14 is a circuit breaker.

[0003] In this configuration, the AC voltage of the AC overhead line 1 is stepped down by the main transformer 2. PWM converter 4,
Reference numeral 5 converts the input alternating current into direct current, and this direct current is smoothed by the smoothing capacitor 6. The VVVF inverter 7 converts the smoothed direct current into an alternating current having a variable voltage and a variable frequency to supply power to the induction motor 9.

At the time of starting the power supply device, an excessive current for initial charging the smoothing capacitor 6 may flow, which may damage the switching elements forming the PWM converters 4 and 5. Therefore, in order to prevent this, Until the start-up is completed, the short-circuit switch 10 is opened, the start-up current is limited by the charging resistor 9, and the switch 11 is opened to disconnect the PWM converter 4.

[0005]

As described above, in the conventional one, the charging resistor 9 and the short-circuit switch 1 are provided in the intermediate DC circuit.
The PWM converter 4 which does not have the parallel circuit of 0 is separated at the time of start-up, so the PWM converter 4 which does not have the parallel circuit
There is a problem in that the switches 11 are required for the number of converters, and the size of the device is correspondingly increased. The present invention has been made to solve this problem, and provides a power supply device for an AC electric vehicle in which even if the number of converters increases, the number of switches that are opened at startup and normally closed is only one. With the goal.

[0006]

In order to achieve the above object, the present invention provides a transformer having a plurality of secondary windings, each of which has a primary winding connected to an overhead wire via a pantograph, and each of the secondary windings. Multiple converters that convert the AC output of the converter to DC power, an inverter that converts the DC power of each converter to AC power and feeds it to the vehicle motor, and a smoothing inserted between the DC side positive and negative terminals of this inverter. A capacitor and a charging resistor that limits the charging current of this smoothing capacitor,
In a power supply device for an AC electric vehicle that includes a short-circuit switch opened at startup inserted in parallel to the charging resistor, a parallel circuit of the charging resistor and the short-circuit switch is inserted between the DC side positive and negative terminals of the inverter. It is configured to be inserted in series with the smoothing capacitor.

According to the present invention, the positive and negative electrodes of the output terminals on the DC side of each converter are directly connected in common, and a charging resistor is connected between one common connection point and the same side of the smoothing capacitor. The parallel circuit of the short circuit switch was inserted.

[0008]

In the present invention, the converters are directly connected in parallel with each other, and the parallel circuit of the charging resistor and the short-circuiting switch is inserted between this connection point and the smoothing capacitor. It is possible to reduce the number of switches that are opened at the time of startup, as compared with the case where the switches are opened and connected in parallel with each other.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a parallel circuit of a charging resistor 9 and a short-circuit switch 10 is inserted in series with a smoothing capacitor 6, and an intermediate DC circuit positive output terminal 4 of a PWM converter 4 is inserted.
a and the intermediate DC circuit positive output terminal 5a of the PWM converter 5
3 is different from that of FIG. 3 in that and are directly connected.

In this configuration, since the PWM converters 4 and 5 are directly connected in parallel and the above-mentioned switch 11 is not used, even if the number of converters in parallel is increased, the switch is opened at startup and closed at steady state. The short-circuit switch 10 is sufficient.

FIG. 2 shows another embodiment of the present invention. The intermediate DC circuit positive output terminal 4a of the PWM converter 4 is shown in FIG.
And the positive terminal 5a of the intermediate DC circuit of the PWM converter 5 are directly connected, and a parallel circuit of the charging resistor 9 and the short-circuit switch 10 is inserted between this connection point and the positive terminal of the smoothing capacitor 6. Has been done. In this circuit, the required capacity of the short-circuit switch 10 is of course increased as compared with the case of the embodiment of FIG.

[0013]

As described above, the present invention does not connect each converter in parallel with each other by opening the switch that is open at the time of startup, but directly connect each converter in parallel with each other and use this common connection. Since a parallel circuit of a charging resistor and a short-circuiting switch is inserted between the point and the smoothing capacitor, only one of the above-mentioned short-circuiting switches needs to be opened at the time of start-up. Cost reduction can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing a conventional power supply device.

[Explanation of symbols]

 1 AC overhead line 2 Pantograph 3 Main transformer 4, 5 PWM control converter 4a, 5a Intermediate DC circuit positive output terminal of converter 6 Smoothing capacitor 7 Variable voltage variable frequency inverter 9 Charging resistor 10 Short circuit switch at start-up

Claims (2)

(57) [Claims] 1. A transformer having a plurality of secondary windings, whose primary winding is connected to an overhead wire via a pantograph, and a plurality of converters for converting the AC output of each secondary winding into DC power. An inverter that converts the DC power of each converter into AC power and feeds it to the vehicle electric motor, a smoothing capacitor inserted between the DC side positive and negative terminals of this inverter, and a charging capacitor that limits the charging current of this smoothing capacitor. In a power supply device for an AC electric vehicle that includes a resistor and a short-circuit switch that is opened at startup and that is inserted in parallel with the charging resistor, a parallel circuit of the charging resistor and the short-circuit switch is provided between the DC side positive and negative terminals of the inverter. A power supply device for an AC electric vehicle, characterized in that the power supply device is inserted in the power supply device and is inserted in series with the smoothing capacitor. 2. A transformer having a plurality of secondary windings, whose primary winding is connected to an overhead wire via a pantograph, and a plurality of converters for converting the AC output of each secondary winding into DC power. An inverter that converts the DC power of each converter into AC power and feeds it to the vehicle electric motor, a smoothing capacitor inserted between the DC side positive and negative terminals of this inverter, and a charging capacitor that limits the charging current of this smoothing capacitor. In a power supply device for an AC electric vehicle that includes a resistor and a short-circuiting switch that opens at start-up and is inserted in parallel with the charging resistor, the positive and negative electrodes of the DC-side output terminals of each converter are directly connected in common. A power supply device for an AC electric vehicle, wherein a parallel circuit of a charging resistor and a short-circuit switch is inserted between one common connection point and the same-polarity side of a smoothing capacitor.