JPH04289703A - Power supply for ac electric vehicle - Google Patents

Abstract

PURPOSE:To provide a power supply for an AC electric vehicle requiring only one switch, being opened at the time of starting and closed during steady operation, even if the number of converter increases. CONSTITUTION:The power supply for AC electric vehicle comprises a plurality of converters 4, 5, an inverter 7 for inverting DC output from each converter into VVVF power, a smoothing capacitor 6 inserted between DC side positive and negative terminals of the inverter 7, a charging resistor 9 for limiting the initial charging current of the smoothing capacitor 6, and a short circuit switch 10 connected in parallel with the charging resistor 9. A parallel circuit of the charging resistor 9 and the short circuit switch 10 is inserted between the positive and negative terminals on DC side of the inverter 7 and connected in series with the smoothing capacitor 6.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] FIG. 3 shows, for example, Japanese Patent Application Laid-Open No. 63-302702
This figure shows the main circuit configuration of the conventional AC electric vehicle control device described in the publication. In the figure, 1 is an AC overhead line, 2 is a pantograph, 3 is a main transformer, 4 and 5 are PWM control converters (hereinafter referred to as PWM converters), 4
a, 5a are intermediate DC circuit positive output terminals of 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, 9 is a charging resistor, 10 is a short-circuit switch that is opened at startup, 11 is a switch that is opened at startup, and 14 is a breaker.

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

[0004] When starting up the power supply, an excessive current flows to initially charge the smoothing capacitor 6, which may damage the switching elements constituting the PWM converters 4 and 5. To prevent this, Until the start-up is completed, the short-circuit switch 10 is opened to limit the start-up current using the charging resistor 9, and the switch 11 is opened to disconnect the PWM converter 4.

[0005]

[Problems to be Solved by the Invention] As described above, in the conventional system, the intermediate DC circuit has a charging resistor 9 and a short circuit switch 1.
Since the PWM converter 4 that does not have a parallel circuit of 0 is disconnected at startup, the PWM converter 4 that does not have a parallel circuit
There is a problem in that the number of switches 11 equal to the number of converters is required, which increases the size of the device. The present invention has been made to solve this problem, and provides a power supply device for an AC electric vehicle that requires only one switch, which is opened at startup and normally closed, even if the number of converters increases. With the goal.

[0006]

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

In claim 2, the positive terminals and the negative terminals of the output terminals on the DC side of each converter are directly connected to each other as a common, and a charging resistor is connected between one common connection point and the same polarity side of the smoothing capacitor. A parallel circuit of a short circuit switch is now inserted.

[0008]

[Operation] In the present invention, each converter is directly connected in parallel with each other, and a parallel circuit consisting of a charging resistor and a shorting switch is inserted between this connection point and the smoothing capacitor. Compared to the case where the switches are open and connected in parallel, the number of switches that are opened at startup can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 shorting switch 10 is inserted in series with a smoothing capacitor 6, and the intermediate DC circuit positive output terminal 4 of the PWM converter 4
a and the intermediate DC circuit positive output terminal 5a of the PWM converter 5
This is different from the one shown in FIG. 3 in that the two are directly connected to each other.

In this configuration, the PWM converters 4 and 5 are directly connected in parallel, and the switch 11 described above is not used. Therefore, even if the number of parallel converters increases, the switch is opened at startup and closed during normal operation. , only the short circuit switch 10 is required.

FIG. 2 shows another embodiment of the present invention, in which the intermediate DC circuit positive output terminal 4a of the PWM converter 4 and the intermediate DC circuit positive output terminal 5a of the PWM converter 5 are directly connected. A parallel circuit including a charging resistor 9 and a shorting switch 10 is inserted between the connection point and the positive end of the smoothing capacitor 6. In this circuit, the required capacity of the shorting switch 10 is of course increased compared to the embodiment of FIG.

[0013]

[Effects of the Invention] As explained above, the present invention does not connect each converter in parallel with each other by opening the switch that opens at startup, but connects each converter directly in parallel with each other, and connects each converter directly to each other in parallel. Since a parallel circuit consisting of a charging resistor and a shorting switch is inserted between the point and the smoothing capacitor, only one shorting switch is required to open at startup.
Compared to conventional methods, the device can be made smaller and less expensive.

[Brief explanation of the drawing]

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 wire 2 Pantograph 3 Main transformers 4, 5 PWM control converters 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 that opens at startup

Claims (2)

[Claims] 1. A transformer having a primary winding connected to an overhead wire via a pantograph and having a plurality of secondary windings, and a plurality of converters that convert the AC output of each of the secondary windings into DC power, An inverter that converts the DC power of each converter into AC power and supplies the power to the vehicle electric motor, and a smoothing capacitor inserted between the positive and negative terminals on the DC side of this inverter,
In a power supply device for an AC electric vehicle, comprising a charging resistor that limits the charging current of the smoothing capacitor, and a short-circuit switch inserted in parallel with the charging resistor and opened at startup, the charging resistor and the short-circuit switch are provided. A power supply device for an AC electric vehicle, characterized in that a parallel circuit is inserted between the positive and negative terminals of the DC side of the inverter and inserted in series with the smoothing capacitor. 2. A transformer having a primary winding connected to an overhead wire via a pantograph and having a plurality of secondary windings, and a plurality of converters that convert the AC output of each of the secondary windings into DC power, An inverter that converts the DC power of each converter into AC power and supplies the power to the vehicle electric motor, and a smoothing capacitor inserted between the positive and negative terminals on the DC side of this inverter,
In a power supply device for an AC electric vehicle that includes a charging resistor that limits the charging current of the smoothing capacitor and a short-circuit switch that opens at startup and is inserted in parallel with the charging resistor, the output terminal on the DC side of each converter The positive electrodes and the negative electrodes of the two are directly connected to each other as a common, and a parallel circuit of a charging resistor and a shorting switch is inserted between one common connection point and the same polarity side of the smoothing capacitor. Electric car power supply.