JP2011097674A - Power supply device for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device for electric vehicle that prevents a CHS unit which controls a charge current of a filter capacitor from being enlarger or complicated, and prevents fuse meltdown and substation trip even if a ground fault occurs in an IGBT or the like in the CHS unit. <P>SOLUTION: The filter capacitor 8 is connected to a DC terminal of an inverter 12 in parallel therewith. The CHS unit 15 includes a charging resistor 9 of the filter capacitor 8 and a CHR short-circuit switch 10, and is connected between a DC terminal on the negative side of the inverter 12 and the ground. Since an overhead wire voltage is not directly applied to the CHS unit 15, a short-circuit current does not flow even if a ground fault occurs in the CHS unit 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply device for an electric vehicle that converts DC power supplied from an overhead wire into three-phase AC power and supplies the power to equipment installed in the electric vehicle.

  In general, in an electric vehicle power supply device, electric power is received from an overhead wire, and the electric power is supplied to an electric vehicle illumination, an air conditioner, and the like. This electric vehicle power supply device acquires the presence or absence of an overhead wire voltage with a voltage detector, and starts operation when a voltage is applied.

  FIG. 3 is a diagram showing a circuit configuration of a conventional electric vehicle power supply device.

  Electric power is supplied from the overhead line 1 to the power supply device 3 for the electric vehicle through the pantograph 2, and the power supply device 3 is grounded through the wheels 4 and the like. The electric vehicle power supply device 3 includes an overcurrent protection fuse 5, a contactor 6, an input filter reactor 7, a charging switch (CHS) unit 15, an input filter capacitor (FC) 8, an inverter 12, an AC filter 13, Consists of a transformer 14 and the like. The secondary side of the transformer 14 is connected to loads such as air conditioning and lighting of the electric vehicle.

  Such an electric vehicle power supply device has a circuit configuration in which an overhead line voltage is supplied to the capacitor 8 through the resistor 9 for a certain period of time in order to suppress an inrush current when electric charge is accumulated in the input filter capacitor 8. . There is a circuit part that short-circuits the resistor 9 after the electric charge is accumulated, and this part is called, for example, a CHS unit. The CHS unit 15 is provided with a semiconductor element and a resistor for the short circuit operation and the backflow prevention. That is, as shown in FIG. 3, the CHS unit 15 includes semiconductor elements such as a CHR short-circuit switch (CHS) 10 and a backflow blocking diode (BD) 11, and an FC charging resistor (CHR) 9. As this semiconductor element, GTO, thyristor, IGBT, or the like is generally used.

  IGBTs used as the short-circuit switch 10 include a pressure contact type IGBT and a module type IGBT. When a module type IGBT is used as the shorting switch 10 built in the CHS unit 15, if the module type IGBT fails due to overvoltage, overcurrent, etc., the internal wiring of the IGBT and the frame of the CHS unit 15 may be short-circuited.

  4A and 4B are diagrams showing a module type IGBT having two IGBTs. FIG. 4A is a schematic view, and FIG. 4B is a diagram showing a state of internal wiring of the IGBT shown in FIG. Note that the IGBT circuit on the right side of FIG. 4B shows a state in which wiring and terminals are destroyed due to a short circuit failure.

  When such a short-circuit failure occurs, if the CHS unit 15 is attached to the electric vehicle power supply without being insulated, or if the withstand voltage level is low, it becomes a ground fault of the electric vehicle power supply, and the fuse It may lead to fusing and substation trips. Here, the trip of the substation indicates a state in which an overcurrent flows through the overhead line and the cutoff switch of the substation is turned off for overcurrent protection.

  An example of the mechanism leading to a ground fault is as follows. That is, between the terminal part of the module type IGBT and the copper plate (the part of the mounting plate under the module case, which is attached to the CHS unit frame), the insulation resistance is originally several tens MΩ to several hundreds MΩ or more. What is present is significantly reduced to about several kΩ due to quality degradation. Then, it connects with a terminal, a copper plate, and a CHS unit frame. Since the frame is connected to the power supply box frame, the vehicle, the rail, that is, the ground, the terminal of the IGBT is directly connected to the ground, resulting in a ground fault.

  When the CHS unit is insulated and attached to the device with sufficiently high insulation so as not to cause a ground fault of the power supply device, a withstand voltage of 2.25 U + 2000 V is required according to JIS regulations. That is, when the rated voltage U is 1500V, a dielectric breakdown voltage of 5375V is required. When the dielectric strength is increased in this way, the cost and size are adversely affected, such as the complexity of the insulating structure, the size of the insulator, and the size of the CHS unit by expanding the space.

  Accordingly, the present invention provides a power supply device for an electric vehicle that does not cause a fuse fusing and a substation trip even if a ground fault occurs in an IGBT or the like in the CHS unit without increasing the size and complexity of the CHS unit. The purpose is to provide.

  In order to solve the above problems, a power supply device for an electric vehicle according to an embodiment of the present invention includes an inverter that is supplied with DC power from an overhead wire and converts the DC power into three-phase AC power, and a DC side of the inverter. A filter capacitor connected in parallel to the terminal, a charging resistor connected between the negative DC terminal of the inverter and the ground, and supplying a charging current to the filter capacitor when the device is started, and the charging resistor And a semiconductor shorting switch that short-circuits the charging resistor after the filter capacitor is charged. The semiconductor short-circuit switch is, for example, a module type IGBT, and this IGBT is provided in the CHS unit.

  For electric vehicles that do not lead to fusing and substation trips even if a ground fault occurs in an IGBT in the CHS unit without increasing the size and complexity of the CHS unit that controls the charging current of the filter capacitor A power supply is provided.

It is a block diagram which shows the structure of 1st Example of the power supply device for electric vehicles by this invention. FIG. 2 is a block diagram showing the configuration of a second embodiment of the electric vehicle power supply device according to the present invention. It is a figure which shows the circuit structure of the conventional electric vehicle power supply device. It is a figure which shows the module type IGBT which has two IGBTs.

  Embodiments of an electric vehicle power supply apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a first embodiment of a power supply device for an electric vehicle according to the present invention.

(Constitution)
DC power is supplied from a substation (not shown) to the electric vehicle power supply device 3 through the overhead wire 1 and the pantograph 2. The electric vehicle power supply device 3 converts the DC power into, for example, 60 Hz, 630 V three-phase AC power, and supplies the AC power to an auxiliary machine such as an air conditioner. The power supply device 3 is grounded via a wheel 4 or the like.

  In the electric vehicle power supply device 3, the electric power supplied from the overhead wire is supplied to the inverter 12 through the protective fuse 5, the contactor 6, and the input filter reactor 7 at the time of overcurrent. An input filter capacitor (FC) 8 is connected in parallel to the DC terminal of the inverter 12, and the AC terminal is connected to the primary side of the transformer 14 via the AC filter 13. The secondary side of the transformer 14 is connected to a load such as air conditioning. The negative DC terminal of the inverter 12 is grounded via the CHS unit 15.

  The CHS unit 15 includes an FC charging resistor (CHR) 9, a CHR short-circuit switch (CHS) 10, and a backflow prevention diode (BD) 11. As the CHS 10, a semiconductor element such as an insulated gate bipolar transistor (IGBT) is used. The CHS unit 15 is composed of the CHS 10 and the BD 11, and the CHR 9 may be externally attached to this unit.

  Conventionally, as shown in FIG. 3, the CHS unit 15 is connected to the overhead line side with respect to the inverter 12, but in this embodiment, it is connected to the ground side as shown in FIG.

(Function)
In this embodiment, since the CHS unit 15 is connected to the ground side of the inverter 12, no overhead voltage is directly applied to the CHS unit 15 by the capacitor 8 and the inverter 12. Therefore, even if the CHS unit 15 is not insulatedly attached to the electric vehicle power supply device 3, if the CHS unit 15 is grounded due to a failure of the CHS 10 or BD 11 in the CHS unit 15, the short-circuit current from the overhead wire 1 to the ground Will not flow. Therefore, an excessive current does not flow through the power supply device 3, and the fuse does not blow or the substation trip occurs.

  As described above, according to one embodiment of the present invention, since it is not necessary to install the CHS unit 15 in an insulating manner, the insulating structure is complicated, the insulator between the CHS unit and the vehicle body is enlarged, and the space is expanded. Therefore, it is not necessary to increase the size of the CHS unit, and the size and cost can be reduced.

  Further, when no charge is accumulated in the filter capacitor 8 at the time of starting the apparatus, conventionally, an overhead line voltage is applied to the resistor CHR9. Therefore, it is necessary to use a high breakdown voltage resistor as the resistor CHR9. However, in this embodiment, since the CHS unit is not directly connected to the overhead wire, the breakdown voltage of the CHR 9 can be kept low.

  Next, a second embodiment of the present invention will be described.

  FIG. 2 is a block diagram showing the configuration of a second embodiment of the electric vehicle power supply device according to the present invention.

(Constitution)
In the second embodiment, a contactor 16 for short-circuiting the CHS unit is added to the first embodiment. The contactor 16 is connected to the CHS unit 15 in parallel. The contactor 16 is a b contact, that is, a contact that closes when not operating.

(Function)
Until the electric vehicle power supply device 3 is operated, the contactor 6 is open and the contactor 16 is closed. When the operation of the electric vehicle power supply device 3 is started, the contactor 16 is opened before the contactor 6 is closed.

  According to the second embodiment of the present invention, by adding the contactor 16 to the configuration of the first embodiment, the potential on the N side (negative DC terminal) of the inverter 12 can be grounded (wheel 4). This becomes possible, and the potential of the inverter 12 does not become floating. Therefore, when the apparatus is not in operation, the high voltage of the capacitor 8 can be prevented from being maintained for a long time, and for example, the safety of the operator can be ensured during inspection.

  The above description is an embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented. For example, it is obvious that the configuration of the present invention can be applied not only to a power supply device for vehicle illumination and air conditioning as described above, but also to a drive device (VVVF inverter) for driving a main motor.

  DESCRIPTION OF SYMBOLS 1 ... Overhead wire, 2 ... Pantograph, 3 ... Electric vehicle power supply device, 4 ... Wheel etc. 5 ... Fuse, 6 ... Contactor, 7 ... Input filter reactor, 8 ... Input filter capacitor (FC), 9 ... For FC charge Resistor (CHR), 10 ... CHR short circuit switch (CHS), 11 ... Backflow blocking diode (BD), 12 ... Inverter, 13 ... AC filter, 14 ... Transformer, 15 ... CHS unit, 16 ... Contactor.

Claims (5)

An inverter that is supplied with DC power from an overhead wire and converts the DC power into three-phase AC power;
A filter capacitor connected in parallel to the DC side terminal of the inverter;
A charging resistor connected between the negative DC terminal of the inverter and the ground, and supplying a charging current to the filter capacitor at the time of starting the device;
A semiconductor short-circuit switch that is connected in parallel to the charging resistor and shorts the charging resistor after the filter capacitor is charged;
An electric vehicle power supply device comprising: An inverter that is supplied with DC power from an overhead wire and converts the DC power into three-phase AC power;
A filter capacitor connected in parallel to the DC side terminal of the inverter;
A CHS unit comprising a series circuit of an IGBT and a reverse current blocking diode, connected between the negative DC terminal of the inverter and the ground;
A charging resistor connected in parallel to the IGBT and for supplying a charging current to the filter capacitor at the start-up of the device;
An electric vehicle power supply device comprising: An inverter that is supplied with DC power from an overhead wire and converts the DC power into three-phase AC power;
A filter capacitor connected in parallel to the DC side terminal of the inverter;
A CHS unit comprising a parallel circuit of an IGBT and a charging resistor, and a reverse current blocking diode connected in series to the parallel circuit, and connected between the negative DC terminal of the inverter and the ground;
An electric vehicle power supply device comprising:   4. A charging resistor having a lower withstand voltage than that of an electric vehicle power supply device in which a filter capacitor charging resistor is connected to a DC terminal on the overhead line side of the inverter is used. 2. The electric vehicle power supply device according to item 1.   The electric vehicle power supply device according to any one of claims 1 to 3, further comprising a contactor connected between the negative DC terminal of the inverter and the ground.

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