JP5330020B2 - Electric vehicle power converter - Google Patents

Description

  The present invention relates to a power conversion device for an electric vehicle mounted on an AC electric vehicle that travels with AC power from an overhead wire.

  An AC electric vehicle that travels with AC power from an overhead line is equipped with a power conversion device including a converter and an inverter. In this power converter, the converter converts AC power input from the power supply side transformer into DC power, and further, the inverter converts the DC power into AC power controlled by a variable voltage and variable frequency to be used as a driving AC motor. Output.

  However, due to the switching operation of each semiconductor element constituting the converter and the inverter, a high frequency current may flow as a leakage current between the main circuit device such as a power supply side transformer and an AC motor and the vehicle body side. This is because a stray capacitance exists between the frame member of the main circuit device and the vehicle body side, and a leakage current flows between the main circuit device and the vehicle body side via the stray capacitance. When such a leakage current flows, there is a possibility that an unexpected accident may occur due to a malfunction of various devices such as an earth leakage breaker and a communication device installed in the vehicle body. Therefore, it is necessary to suppress such leakage current as much as possible.

  Conventionally, as a countermeasure for suppressing leakage current, for example, there is one disclosed in Patent Document 1. In the configuration according to Patent Document 1, filter circuits are respectively added to the input side and the output side of the power converter.

Japanese Patent No. 3211073

  However, in the configuration of Patent Document 1, the filter circuit has to be disposed in a limited space such as under the floor of the vehicle body, and the weight increases by the additional amount of the filter circuit. It has the disadvantage of becoming smaller.

  Further, in the configuration of Patent Document 1, since the floating capacitance existing inside the module of each semiconductor element constituting the converter and the inverter is not particularly taken into consideration, it is difficult to reduce the leakage current to a certain level or less. .

  FIG. 7 is an explanatory diagram showing a problem of the conventional device, that is, an explanatory diagram showing a path of a high-frequency leakage current that flows due to stray capacitance existing inside each semiconductor element module in the conventional device.

  In FIG. 7, AC power is sent from the overhead line (not shown) to the power supply side transformer 1 via the pantograph. The power conversion device 2 converts the AC power input from the power supply side transformer 1 into power, and then outputs this to the AC motor 3 for driving an electric vehicle.

  The power conversion apparatus 2 includes a converter 4 having a semiconductor element module 5 and an inverter 6 having a semiconductor element module 7. The converter 4 and the inverter 6 are connected by a DC link unit 8. The DC link unit 8 has a P line, an O line (neutral point), and an N line, and both ends of a plurality of smoothing capacitors 9 are connected between the P line and the O line and between the O line and the N line. Has been.

  Here, in the illustration of FIG. 7, the block line indicating the power conversion device 2 is assumed to indicate the device-side metal casing at the same time, and may be denoted by the same reference numeral 2 as appropriate. Similarly, a block line indicating the converter 4 may simultaneously indicate a converter-side metal housing and may be appropriately denoted by the same reference numeral 4. Similarly, the line of the block indicating the inverter 6 is assumed to indicate the inverter-side metal casing at the same time, and may be denoted by the same reference numeral 6 as appropriate.

  The device-side metal housing 2 is provided with an insulating terminal 10 that is grounded to the vehicle body side. Various devices arranged inside the apparatus-side metal housing 2 are connected to the insulated terminal 10 by wiring materials, and these various devices are grounded together. As described above, if a plurality of wiring materials are connected together in one place, it is convenient to separate each wiring material from the insulated terminal 10 when performing a pressure resistance test or the like of various devices ( Actually, an opening / closing switch or the like is provided in the wiring material, and this switch can be turned off at the time of the pressure resistance test.

  One end side of a ground circuit 11 composed of a capacitor and a resistor connected in parallel is connected to the O line of the DC link unit 8, and the other end side is connected to the insulation terminal 10. In addition, although the power converter device 2 of FIG. 7 has shown the example comprised by the converter 4 and inverter 6 of the 3 level electric potential type provided with O line (neutral point), this power converter device 2 is shown. It may be composed of a normal type converter and inverter that are not provided with an O-line (however, the three-level potential type has voltage fluctuations centered on zero potential, so that the withstand voltage capacity can be reduced. There is.)

  The converter side metal housing 4 is fixed to the vehicle body side together with the device side metal housing 2 by a bolt member 12, and the inverter side metal housing 6 is also fixed to the vehicle body side together with the device side metal housing 2 by a bolt member 13. Has been. Therefore, the converter-side metal housing 4, the inverter-side metal housing 6, and the device-side metal housing 2 are electrically connected to the vehicle body side via the bolt members 12 and 13 and are grounded. That is, the bolt members 12 and 13 have a function as an electrically conductive member in addition to a function as a fixing member for the vehicle body side. As a result, the wiring material connection for grounding (connection for preventing an electric shock when a maintenance worker contacts the converter-side metal housing 4 or the inverter-side metal housing 6 in the state of leakage) is omitted. It has become.

  The device-side metal housing 2 is connected to one end side of the device-side external wiring member 14 and the other end side to the vehicle body side. The device-side external wiring member 14 is provided to prevent an electric shock accident when a maintenance worker comes into contact with the device-side metal casing 2 in a leakage state. The device-side external wiring member 14 seems unnecessary because the device-side metal housing 2 is grounded to the vehicle body side by the bolt members 12 and 13, but the converter-side metal housing 4 and the inverter-side metal housing 14 are not necessary. When only the body 6 is fixed to the vehicle body side by the bolt members 12 and 13, or when the vehicle body side to which the bolt members 12 and 13 are fixed is electrically insulated from the other vehicle body side Etc. are provided in consideration of the possibility.

  Next, the operation of the power conversion device 2 in FIG. 7 will be described. When the converter 4 receives AC power from the power supply side transformer 1, the input AC power is converted into DC power by the switching operation of the semiconductor element (IGBT in the example of FIG. 7) forming the semiconductor element module 5. Output. This DC power is smoothed by the smoothing capacitor 9 of the DC link unit 8 and sent to the inverter 6. When the smoothed DC power is input, the inverter 6 performs variable voltage variable frequency control on the input DC power by switching operation of the semiconductor element (IGBT in the example of FIG. 7) forming the semiconductor element module 7. This is converted into AC power and output to the AC motor 3.

  However, when the power conversion device 2 performs such a power conversion operation, because of the stray capacitance SC1 existing between the semiconductor element chip forming the semiconductor element module 5 on the converter 4 side and the module case. Leakage current is generated. There is also a stray capacitance between the semiconductor element module 5 and the converter side metal casing 4, and the converter side metal casing 4 and the device side metal casing 2 are electrically connected by the bolt member 12. As a result, the leakage current leaks from the device-side external wiring member 14 to the vehicle body side through the device-side metal housing 2 as indicated by reference numeral IL1.

  The same thing occurs on the inverter 6 side, and a leakage current is generated due to the stray capacitance SC2 existing between the semiconductor element chip forming the semiconductor element module 7 and the module case. Then, as indicated by reference numeral IL2, this leakage current leaks from the apparatus-side external wiring member 14 to the vehicle body side along with the leakage current IL1 through the apparatus-side metal casing 2.

  The vehicle body to which the other end side of the apparatus-side external wiring member 14 is connected and the vehicle body to which the insulation terminal 10 is connected are electrically connected by the vehicle body constituent material although the distance is long. Therefore, the leakage currents IL1 and IL2 leaked from the device-side external wiring member 14 to the vehicle body side become leakage currents IL3, which reach the O line of the DC link portion 8 through the insulation terminal 10 and the ground circuit 11, and from here 2 It branches into two and returns to the semiconductor element modules 5 and 7, respectively.

  As described above, in the configuration of FIG. 7, since the bolt members 12 and 13 and the apparatus-side external wiring member 14 are provided, the leakage current generated due to the floating capacitances SC1 and SC2 of the semiconductor element modules 5 and 7. IL1 and IL2 leak along the apparatus-side metal housing 2 from the apparatus-side external wiring member 14 to the vehicle body side. The leakage current is returned to the semiconductor element modules 5 and 7 through the insulation terminal 10 and the ground circuit 11.

  Various devices such as a communication device are arranged on the vehicle body side. When the leakage current as described above passes through a long-distance current path formed by the metal casing and the vehicle body, these various devices are arranged. Will be adversely affected. In the conventional apparatus including the apparatus according to Patent Document 1, the leakage current generated due to the stray capacitance of the semiconductor element module is not particularly taken into consideration in this way, so that the entire leakage current is kept below a certain level. It is difficult to reduce, and it has not been possible to sufficiently suppress adverse effects on various devices such as communication devices.

  The present invention has been made in view of the above circumstances, and while having a simple configuration, the leakage amount of leakage current generated due to the stray capacitance of the semiconductor element module to the vehicle body side is reduced as much as possible. It is an object of the present invention to provide an electric vehicle power converter that can sufficiently suppress adverse effects on various devices such as a communication device disposed in the vehicle.

As means for solving the above problems,
The invention according to claim 1 is a converter that converts AC power input from a power supply side transformer into DC power;
An inverter that converts the DC power input from the converter into AC power controlled by a variable voltage and variable frequency and outputs the AC power to a driving AC motor;
A device-side metal housing that houses the converter and the inverter and has an insulating terminal grounded to the vehicle body;
One end side is connected to the DC link portion connecting the converter and the inverter, and the other end side is connected to the insulated terminal, and a ground circuit,
A bolt member that fixes the converter side metal casing of the converter and the inverter side metal casing of the inverter to the vehicle body side and electrically conducts,
One end side is connected to the device side metal housing, the other end side is connected to the vehicle body side, and the device side external wiring material,
An electric vehicle power conversion device comprising:
One end side is connected to the converter side metal casing, and the other end side is connected to the insulated terminal, and leakage current generated due to a floating capacitance inside the semiconductor element module constituting the converter is grounded. Converter-side wiring material for returning to the converter side via the circuit and the DC link part;
One end side is connected to the inverter side metal casing, and the other end side is connected to the insulated terminal, and leakage current generated due to stray capacitance inside the semiconductor element module constituting the inverter is grounded. An inverter side wiring material for returning to the inverter side via the circuit and the DC link part;
In an electric vehicle power converter having
The converter side wiring material and the inverter side wiring material are provided with a low impedance member that becomes a low impedance with respect to a high frequency leakage current ,
It is characterized by that.

  According to a second aspect of the present invention, in the first aspect of the invention, one end side is connected to a portion of the device side metal casing to which one end side of the device side external wiring member is connected, and the other end side is the insulated terminal. Connected to the converter side metal casing and the leakage current generated due to stray capacitance between the inverter side metal casing and the apparatus side metal casing, the ground circuit and the DC link section And a device-side internal wiring material for returning the current to the converter side and the inverter side, respectively.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a high impedance member having a high impedance against a high frequency leakage current is interposed between the insulated terminal and the vehicle body side. And

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the device-side external wiring member is provided with a high-impedance member that has a high impedance against a high-frequency leakage current. And

  According to the present invention, the communication device is arranged on the vehicle body side by reducing the leakage amount of the leakage current generated due to the stray capacitance of the semiconductor element module to the vehicle body as much as possible while having a simple configuration. It is possible to sufficiently suppress adverse effects on various devices such as the above.

The block diagram of the 1st Embodiment of this invention. The block diagram of the 2nd Embodiment of this invention. The block diagram of the 3rd Embodiment of this invention. The block diagram of the 4th Embodiment of this invention. The block diagram of the 5th Embodiment of this invention. The block diagram which shows the reference example of this invention. Explanatory drawing about the subject of a conventional apparatus.

  FIG. 1 is a configuration diagram of a first embodiment of the present invention. In addition, about the component similar to the component mentioned already in FIG. 7, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  1 is different from FIG. 7 in that a converter side wiring member 101 and an inverter side wiring member 102 are added. That is, in the present embodiment, one end side of the converter side wiring member 101 is connected to the converter side metal housing 2 and the other end side is connected to the insulating terminal 10. Similarly, one end side of the inverter side wiring member 102 is connected to the inverter side metal casing inverter 6, and the other end side is connected to the insulating terminal 10.

  If the converter-side wiring member 101 is connected as shown in FIG. 1, the semiconductor element module 5, the bolt member 12, the device-side metal housing 2, the device-side external wiring member 14, the vehicle body side, the insulated terminal 10, and the ground circuit 11, the impedance of the loop circuit formed by the O line and the semiconductor element module 5 (that is, the current paths of the leakage currents IL1 and IL3 in FIG. 7), the semiconductor element module 5, the converter side wiring material 101, the insulated terminal 10, The impedance of the loop circuit formed by the ground circuit 11, the O line, and the semiconductor element module 5 becomes smaller.

  Accordingly, the leakage current IL10 caused by the stray capacitance SC1 of the semiconductor element module 5 flows through the latter loop circuit and does not flow through the former loop circuit, as shown in FIG. The same can be said for the inverter-side metal housing 6, and the leakage current IL20 caused by the stray capacitance SC2 of the semiconductor element module 7 flows through the loop circuit as shown.

  That is, by changing the paths of the leakage currents IL1, IL2, and IL3 in FIG. 7 to the paths of the leakage currents IL10 and IL20 in FIG. Leakage current leaking into the vehicle can be reduced, and adverse effects on various devices arranged on the vehicle body side can be sufficiently suppressed. And since the structure of FIG. 1 is a simple structure which only added the wiring material, it does not cause a cost increase and a required space does not increase.

  It should be noted that the “wiring material” in the present invention is widely understood and includes a bar-shaped member formed of a good electric conductor in addition to a cable or the like.

  FIG. 2 is a configuration diagram of the second embodiment of the present invention. 2 is different from FIG. 1 in that a device-side internal wiring member 103 is added. That is, one end side of the device-side internal wiring member 103 is connected to the part of the device-side metal housing 2 to which one end side of the device-side external wiring member 14 is connected, and the other end side of the device-side internal wiring member 103 is insulated terminal. 10 is connected.

  Although not shown in FIG. 1, there are actually some stray capacitances SC3 and SC4 between the converter side metal housing 4 and the inverter side metal housing 6 and the device side metal housing 2. ing. When these stray capacitances SC3 and SC4 are large, leakage currents IL4 and IL5 flow along the apparatus-side metal housing 2, and these leakage currents IL4 and IL5 pass through the apparatus-side external wiring member 14 and the vehicle body. Try to leak to the side.

  However, according to the configuration of FIG. 2, since the device-side internal wiring member 103 is provided, the leakage currents IL4 and IL5 do not leak to the vehicle body side through the device-side external wiring member 14, but the leakage current IL30. To the insulated terminal 10. The leakage current IL30 is returned to the converter 4 and the inverter 6 side through the ground circuit 11 and the O line together with the leakage currents IL10 and IL20. Therefore, the leakage current leaking from the apparatus-side external wiring member 14 to the vehicle body side can be further reduced as compared with the configuration of FIG.

  FIG. 3 is a block diagram of the third embodiment of the present invention. 3 differs from FIG. 1 in that a high-impedance member 104 (for example, a magnetic core) that has a high impedance with respect to a high-frequency current is interposed between the insulating terminal 10 and the vehicle body side.

  In the configuration of FIG. 1, high-frequency leakage currents IL10 and IL20 that reach the insulated terminal 10 from the converter-side metal housing 4 and the inverter-side metal housing 6 via the converter-side wiring material 101 and the inverter-side wiring material 102, respectively, The high frequency current is returned to the converter 4 and the inverter 6 through a capacitor in the ground circuit 11 having a low impedance. However, since the insulated terminal 10 is grounded to the vehicle body side, it is conceivable that some of the leakage currents IL10 and IL20 leak to the vehicle body side although it is small.

  Therefore, in the configuration of FIG. 3, a high impedance member 104 such as a magnetic core is provided between the insulating terminal 10 and the vehicle body side so as to suppress the amount of current leaking from the insulating terminal 10 to the vehicle body side as much as possible. Therefore, according to the configuration of FIG. 3, the leakage current that leaks from the insulated terminal 10 to the vehicle body side can be further reduced.

  FIG. 4 is a configuration diagram of the fourth embodiment of the present invention. 4 is different from FIG. 3 in that a high impedance member 105 is also provided on the device-side external wiring member 14.

  As described above with reference to FIG. 2, a certain amount of stray capacitances SC3 and SC4 exist between the converter-side metal housing 4 and the inverter-side metal housing 6 and the device-side metal housing 2, so that leakage occurs. The currents IL4 and IL5 attempt to leak to the vehicle body side through the device-side external wiring member 14 through the device-side metal housing 2.

  However, according to the configuration of FIG. 4, the leakage current leaking to the vehicle body side through the device-side external wiring member 14 can be sufficiently suppressed by the function of the high impedance member 105.

  FIG. 5 is a configuration diagram of the fifth embodiment of the present invention. FIG. 5 is different from FIG. 1 in that low impedance members 106 and 107 (capacitors in this embodiment) having low impedance with respect to a high-frequency current are provided in the converter side wiring member 101 and the inverter side wiring member 102. is there.

  As described above with reference to FIG. 1, if the converter side wiring member 101 connects between the device side metal casing 2 and the insulated terminal 10, the bolt member 12, the vehicle body side, the apparatus side metal casing 2, etc. Since the impedance of the loop circuit formed by the converter-side wiring material 101, the insulation terminal 10, the ground circuit 11 and the like is smaller than the impedance of the loop circuit formed by the leakage current IL10 from the floating capacitance SC1, As illustrated, it flows to the converter side wiring member 101 side (the same applies to the leakage current IL20 from the floating capacitance SC2).

  However, since the converter side metal casing 4 is electrically connected to the apparatus side metal casing 2 and the vehicle body side by the bolt member 12, the leakage current to the bolt member 12 side can be completely zero. Can not. Therefore, it is convenient if the bolt member 12 can be provided with a high impedance member such as a magnetic core used in FIG. 3 or FIG. 4, but such a configuration is difficult to adopt (bolt member). The same applies to 13).

  Therefore, in this embodiment, instead of providing the high impedance member on the bolt members 12 and 13 side, the low impedance members 106 and 107 are provided on the converter side wiring members 101 and 102, and the floating capacitances SC1 and SC2 are used. Most of the leakage currents IL10 and IL20 can be led to the converter side wiring members 101 and 102 side, and the leakage current to the bolt members 12 and 13 side is made as close to zero as possible. Therefore, according to the configuration of FIG. 5, the leakage current leaking to the vehicle body side can be further reduced than the configuration of FIG. 1.

  FIG. 6 is a block diagram showing a reference example of the present invention. 7 and FIGS. 1 to 5 described so far, the converter-side metal casing 4, the inverter-side metal casing 6, and the apparatus-side metal casing 2 are mounted on the vehicle body side using the bolt members 12 and 13. The bolt members 12 and 13 were grounded and fulfilled two functions of a function as a fixing member and a function as an electrical conduction member. However, in the power conversion device, the bolt members 12 and 13 are electrically insulated, the bolt members 12 and 13 are used only as fixing members, and the function as an electrical conduction member is provided separately. There is also a configuration that is made to bear on the material.

  That is, in FIG. 6, the bolt member 12 is covered with an insulating member 108 such as an insulating sleeve, and the bolt member 12 electrically connects the converter-side metal housing 4 and the device-side metal housing 2 to the vehicle body side in an electrically insulated state. It is fixed to. Similarly, the bolt member 13 is covered with an insulating member 109, and the bolt member 13 fixes the inverter-side metal housing 6 and the device-side metal housing 2 to the vehicle body side in an electrically connected state.

  The converter side metal housing 4 and the device side metal housing 2 are connected by a converter side wiring member 110. Similarly, the inverter side metal casing 6 and the apparatus side metal casing 2 are connected by an inverter side wiring member 111.

  However, simply connecting these wiring members 110 and 111 can prevent an electric shock accident when contacting the converter side metal casing 4 or the inverter side metal casing 6, but the leakage currents IL11 and IL21 are connected to the device side metal. Through the housing 2 and the apparatus-side external wiring member 14, the leakage occurs to the vehicle body side as in the conventional case. However, in the reference example of FIG. 6, since these wiring members 110 and 111 are provided with high impedance members 112 and 113 such as a magnetic core, the device side metal casing 2 and the device are connected to these wiring members 110 and 111. It is possible to suppress the leakage current amount leaking to the vehicle body side through the side external wiring member 14 as much as possible.

1: Power supply side transformer 2: Power conversion device (device side metal casing)
3: AC motor 4: Converter (converter side metal casing)
5: Semiconductor element module 6: Inverter (inverter side metal casing)
7: Semiconductor element module 8: DC link portion 9: Smoothing capacitor 10: Insulation terminal 11: Ground circuit 12: Bolt member 13: Bolt member 14: Device side external wiring material 101: Converter side wiring material 102: Inverter side wiring material 103 : Device side internal wiring materials 104 and 105: High impedance members 106 and 107: Low impedance members 108 and 109: Insulating members 110: Converter side wiring materials 111: Inverter side wiring materials 112 and 113: High impedance members SC1 to SC4: Floating Capacitances IL1, IL2: Leakage currents IL10, IL20, IL30: Leakage currents IL11, IL21: Leakage currents
P: P line
O: O line (neutral point)
N: N line

Claims (4)

A converter that converts AC power input from the power transformer to DC power;
An inverter that converts the DC power input from the converter into AC power controlled by a variable voltage and variable frequency and outputs the AC power to a driving AC motor;
A device-side metal housing that houses the converter and the inverter and has an insulating terminal grounded to the vehicle body;
One end side is connected to the DC link portion connecting the converter and the inverter, and the other end side is connected to the insulated terminal, and a ground circuit,
A bolt member that fixes the converter side metal casing of the converter and the inverter side metal casing of the inverter to the vehicle body side and electrically conducts,
One end side is connected to the device side metal housing, the other end side is connected to the vehicle body side, and the device side external wiring material,
An electric vehicle power conversion device comprising:
One end side is connected to the converter side metal casing, and the other end side is connected to the insulated terminal, and leakage current generated due to a floating capacitance inside the semiconductor element module constituting the converter is grounded. Converter-side wiring material for returning to the converter side via the circuit and the DC link part;
One end side is connected to the inverter side metal casing, and the other end side is connected to the insulated terminal, and leakage current generated due to stray capacitance inside the semiconductor element module constituting the inverter is grounded. An inverter side wiring material for returning to the inverter side via the circuit and the DC link part;
In an electric vehicle power converter having
The converter side wiring material and the inverter side wiring material are provided with a low impedance member that becomes a low impedance with respect to a high frequency leakage current ,
An electric vehicle power converter characterized by the above. One end side is connected to a portion of the apparatus side metal casing to which one end side of the apparatus side external wiring member is connected, and the other end side is connected to the insulation terminal, and the converter side metal casing and the inverter side In order to return the leakage current generated due to the stray capacitance between the metal housing and the device-side metal housing to the converter side and the inverter side through the ground circuit and the DC link unit, respectively. Internal wiring material on the device side,
The electric power converter for an electric vehicle according to claim 1, comprising: Between the insulated terminal and the vehicle body side, a high impedance member that becomes high impedance with respect to the high frequency leakage current is inserted,
The electric power converter for electric vehicles according to claim 1 or 2. The device-side external wiring material is provided with a high-impedance member that has a high impedance against high-frequency leakage current.
The electric power converter for an electric vehicle according to any one of claims 1 to 3.

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