JP2017169352A - Power conversion device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively achieve a mechanism for discharging a smoothing capacitor upon vehicle collision in a power conversion device for converting power of a power source to driving power of a running motor.SOLUTION: A power conversion device 10 comprises, inside its housing 14, a smoothing capacitor 13 for smoothing current supplied from a battery, and a positive electrode bus bar 12a and a negative bus bar 12b for transmitting power of the battery to the smoothing capacitor 13. In the housing 14, a fragile part 15 is provided which is separated to the inside of the housing 14 when a load equal to or more than a predetermined magnitude is applied thereto. A part of the positive electrode bus bar 12a and a part of a negative bus bar 12b are opposite to the rear surface of the fragile part 15 so that the separated fragile 15 comes into contact with both of the positive electrode 12a and the negative electrode bus bar 12b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power converter that converts electric power of a power source into driving power of a traveling motor.

  In many cases, a power conversion device that converts power of a power source into driving power of a motor for driving includes a smoothing capacitor between a power positive line and a power negative line that transmit power of the power source. The smoothing capacitor removes noise superimposed on the current from the power supply (or the current after voltage conversion). Since the electric power for driving the traveling motor is a high voltage, it is desirable that the power converter has a mechanism for quickly discharging the smoothing capacitor in the event of a collision. For example, Patent Literature 1 and Patent Literature 2 disclose techniques for quickly discharging a smoothing capacitor. The technique of patent document 1 is as follows. In the power conversion device, a locking rod is locked to a relay that discharges the smoothing capacitor. Normally, the relay is held open by the locking rod, and the discharge circuit of the smoothing capacitor is cut off. When the power converter is moved rearward due to the collision load, the locking rod is removed from the relay, and the smoothing capacitor is connected to the discharge circuit. The technique of patent document 2 is as follows. The power converter is provided with a short-circuit bracket. The short-circuit metal fitting passes through the housing of the power control device and faces the two terminals inside the housing. The two terminals are electrically connected to the respective electrodes of the smoothing capacitor. When the portion exposed to the outside of the casing receives an external force (collision load), the short-circuit metal fitting is pushed into the casing and contacts with the two terminals to conduct between the two terminals. When the two terminals are conducted, the smoothing capacitor is short-circuited and discharged.

JP 2011-125183 A JP 2010-183803 A

  The technique disclosed in Patent Document 1 requires a locking rod that switches the relay from an open state to a conductive state when a load is applied. Moreover, in the technique disclosed in Patent Document 2, a short-circuit fitting that penetrates the casing of the power conversion device is required. Any of the techniques in any of the documents requires a dedicated component for discharging the smoothing capacitor in the event of a collision, which increases costs. This specification provides a technique for realizing a mechanism for discharging a smoothing capacitor at the time of a collision at a low cost.

  A power conversion device disclosed in the present specification includes a smoothing capacitor that smoothes a current supplied from a power source, and a positive electrode bus bar and a negative electrode bus bar that transmit power from the power source to the smoothing capacitor. . The casing is provided with a fragile portion that is detached from the inside of the casing when a load of a predetermined size or more is applied. A part of the positive electrode bus bar and a part of the negative electrode bus bar are opposed to the back surface of the weak part at a predetermined distance so that the detached weak part comes into contact with both the positive electrode bus bar and the negative electrode bus bar. In this power conversion device, the weakened portion that is separated by the load at the time of the collision short-circuits the positive electrode bus bar and the negative electrode bus bar, and discharges the smoothing capacitor. This power conversion device can be realized at low cost because it does not require a dedicated component for discharging. Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a block diagram of the electric power system of the electric vehicle containing the power converter device of an Example. It is sectional drawing of a power converter device. It is sectional drawing showing a mode when a weak part leaves | separates from a housing | casing. It is sectional drawing of the power converter device of a 1st modification. It is sectional drawing of the power converter device of a 2nd modification.

  A power converter according to an embodiment will be described with reference to the drawings. The power conversion device 10 according to the embodiment is mounted on an electric vehicle. FIG. 1 shows a block diagram of a power system of an electric vehicle including a power conversion device 10. In FIG. 1, a region surrounded by an ellipse shows a partial cross section of the casing 14 of the power conversion device 10. Although FIG. 1 is a circuit block diagram, only a region surrounded by an ellipse shows a part of hardware.

  The electric vehicle travels with the travel motor 6. Hereinafter, the traveling motor 6 is simply referred to as a motor 6. The power conversion device 10 converts the DC power of the in-vehicle battery 2 (power source) into AC power having an appropriate frequency and supplies the AC power to the motor 6. In other words, the power conversion device 10 converts the power of the battery 2 into the driving power of the motor 6. The battery 2 and the power conversion device 10 are connected via the system main relay 3. The system main relay 3 and the power conversion device 10 are controlled by the host controller 7.

  The power converter 10 includes a voltage converter circuit 4, a smoothing capacitor 13, and an inverter circuit 5 therein. The voltage converter circuit 4 has both functions of a step-up operation for boosting the voltage of the battery 2 and supplying the boosted voltage to the inverter circuit 5 and a step-down operation for stepping down the regenerative power sent from the inverter circuit 5 and supplying it to the battery 2. Yes. That is, the voltage converter circuit 4 is a bidirectional DC-DC converter. The voltage converter circuit 4 includes a filter capacitor, a reactor, two switching elements, and a freewheeling diode connected in antiparallel to each switching element. The voltage converter circuit 4 shown in FIG. 1 is well known and will not be described in detail.

  The inverter circuit 5 converts the DC power of the battery 2 supplied through the voltage converter circuit 4 into AC power and supplies the AC power to the motor 6. When the driver steps on the brake pedal, the inverter circuit 5 converts AC power generated by the motor 6 by reverse driving into DC power and supplies it to the voltage converter circuit 4. The voltage converter circuit 4 and the inverter circuit 5 operate according to a command from the host controller 7. A smoothing capacitor 13 is connected in parallel between the voltage converter circuit 4 and the inverter circuit 5.

  The voltage converter circuit 4, the smoothing capacitor 13, and the inverter circuit 5 are connected by an elongated metal plate called a bus bar. Since FIG. 1 is a circuit block diagram, the connection is drawn as a simple line, but in the ellipse of FIG. 1, a part of the positive bus bar 12a and the negative bus bar 12b that transmits the power of the battery 2 to the smoothing capacitor 13 is shown. It is drawn.

  The smoothing capacitor 13 is provided to remove a noise component superimposed on the output current of the voltage converter circuit 4 (current supplied from the battery 2). The output of the motor 6 for traveling is as large as several tens of kilowatts. Therefore, the output of the battery 2 is also several tens of kilowatts, and the output voltage is, for example, 300 volts. The voltage converter circuit 4 boosts the output voltage of the battery 2 to, for example, 600 volts. Large power is applied to the smoothing capacitor 13 connected to the output terminal of the voltage converter circuit 4. Therefore, it is desirable that the smoothing capacitor 13 be discharged quickly when the vehicle collides. In the power conversion device 10 of the embodiment, when a load of a predetermined value or more is applied to the casing 14 of the power conversion device 10 at the time of a collision, the positive and negative bus bars connected to the smoothing capacitor 13 are short-circuited, and the smoothing capacitor 13 It has a structure that discharges. The structure will be described below. When the host controller 7 receives a signal from the airbag sensor 8 that detects a collision (a signal indicating that a collision has occurred), the host controller 7 opens the system main relay 3, and the voltage converter circuit 4 and the inverter of the power converter 10. The circuit 5 is stopped.

  As shown in the ellipse in FIG. 1, the casing 14 is provided with a fragile portion 15 that is detached to the inside when a load of a predetermined size or more is applied. A part of the positive electrode bus bar 12a and the negative electrode bus bar 12b that transmits the electric power of the battery 2 to the smoothing capacitor 13 is disposed close to the back surface of the fragile portion 15 with a predetermined distance therebetween. The fragile portion 15 is a region surrounded by the ring-shaped groove 14 a in the housing 14. In the portion corresponding to the groove bottom of the ring-shaped groove 14a, the thickness of the housing 14 is thinner than the other portions. When a collision load is applied, a part of the housing 14 along the groove bottom of the groove 14a ( The fragile part 15) is designed to break. The housing 14 including the fragile portion 15 is made of a conductive metal. When the fragile portion 15 is pushed into the housing 14 by receiving a load from the outside, the conductive fragile portion 15 contacts the positive electrode bus bar 12a and the negative electrode bus bar 12b, short-circuits both, and the smoothing capacitor 13 is discharged. .

  FIG. 2 shows a cross-sectional view of the power conversion device 10. FIG. 3 shows a cross-sectional view of the power conversion device 10 when the fragile portion 15 is detached by receiving a load. 2 and 3, the outline of the front portion of the electric vehicle 90 is drawn with virtual lines. 2 and 3 are cross-sectional views of the power conversion device 10 cut along a plane extending in the vehicle longitudinal direction and the vertical direction. 2 and 3, the internal structure of the power conversion device 10 is schematically illustrated for explanation. In order to help understanding, the power conversion device 10 is drawn relatively large with respect to the size of the electric vehicle 90. The same applies to FIGS. 4 and 5 below. In the drawing, the F axis of the coordinate system faces the front of the vehicle, the H axis faces the vehicle width direction, and the V axis faces upward. The meaning of each axis in the coordinate system is the same in FIGS.

  The power converter 10 is mounted in a vehicle front space (front compartment) of the electric vehicle 90. The power conversion device 10 is fixed to, for example, a frame member 21 that extends in the front-rear direction. Since the power converter 10 is mounted in the front space of the vehicle, there is a high possibility of receiving a collision load on the front surface in the case of a forward collision. The power converter 10 is provided with a fragile portion 15 on a surface that is highly likely to receive a load during a collision (in the case of the present embodiment, the front surface). As described above, the fragile portion 15 is a region surrounded by the ring-shaped groove 14a in the housing 14, and when a load of a predetermined size or more is applied to this region, the bottom of the ring-shaped groove 14a is formed. Thus, the housing 14 is broken, and the fragile portion 15 is detached from the housing 14. The arrow indicated by the symbol W in FIG. 3 indicates the load applied to the power converter 10 in the event of a collision. The power converter 10 is provided with a fragile portion 15 at a location where the housing 14 is likely to receive a load in the event of a collision.

  The housing 14 including the fragile portion 15 is made of a conductive metal such as aluminum. The positive electrode bus bar 12a and the negative electrode bus bar 12b are located at a predetermined distance from the back surface so as to face the back surface of the fragile portion 15. As described above, the positive bus bar 12 a and the negative bus bar 12 b are conductors that transmit the power of the battery 2 to the smoothing capacitor 13. 2 and 3, the hatched cross sections of the positive bus bar 12a and the negative bus bar 12b continue to a connector (not shown), and the smoothing capacitor 13 includes the connector and the system main relay 3 of FIG. It is electrically connected to the battery 2 via. As described above, in FIGS. 1 and 2, the internal structure of the power conversion device 10 is schematically illustrated, and the components other than the smoothing capacitor 13, the positive electrode bus bar 12 a, and the negative electrode bus bar 12 b are omitted.

  As shown in FIG. 3, when the fragile portion 15 receiving the load W is separated from the housing 14 and pushed into the housing, the fragile portion 15 comes into contact with the positive electrode bus bar 12 a and the negative electrode bus bar 12 b and both are short-circuited. . Since the positive electrode bus bar 12a and the negative electrode bus bar 12b are electrically connected to the respective electrodes of the smoothing capacitor 13, when the positive electrode bus bar 12a and the negative electrode bus bar 12b are short-circuited, the smoothing capacitor 13 is discharged. As described above, the power conversion device 10 has a structure for discharging the smoothing capacitor 13 using the impact of the collision. In addition, the structure can be realized at low cost because the casing 14, the positive bus bar 12a, and the negative bus bar 12b, which are originally provided in the power converter 10, are used.

  The modification of the power converter device of an Example is demonstrated. In FIG. 4, sectional drawing of the power converter device 10a of a 1st modification is shown. The power converter 10a of the modified example is also mounted in the front compartment of the electric vehicle 90 in the same manner as the power converter 10 described above. Therefore, at the time of a forward collision, the power conversion device 10a is highly likely to receive a load on the front surface thereof. As will be described in detail later, the power conversion device 10 a also has a weak portion 115 provided on the front surface of the housing 114 in the same manner as the power conversion device 10.

  The power converter 10a is obtained by adding a load guiding member 22 to the power converter 10 of the embodiment. The load guiding member 22 is attached to the front surface of the housing 114 provided with the fragile portion 115 via a flexible support bracket 23. The load guiding member 22 extends over the entire front surface of the housing 114. Further, the load guiding member 22 includes a protruding portion 22 a at a portion facing the fragile portion 115. At the time of a forward collision, the support bracket 23 is deformed when receiving a collision load, and the load guiding member 22 is moved backward. When the load guiding member 22 moves backward, the protruding portion 22a on the rear surface presses the fragile portion 115, and the fragile portion 115 is reliably detached from the housing 114. A rib 114b is provided on the back surface of the housing 114 so as to surround a groove 114a that defines the range of the fragile portion 115. The rib 114b reinforces the periphery of the fragile portion 115. In the power conversion device 10a of the modified example, the load guide member 22 having a larger area than the fragile portion 115 extends widely in a region where a load is assumed to be generated at the time of a forward collision, and the load point at the time of the collision is slightly deviated from the assumption. However, the load is guided to the fragile portion 115. By including the load guiding member 22, the certainty that the fragile portion 115 is detached from the housing 114 at the time of a collision is increased. That is, the power converter 10a of the modified example includes the load guiding member 22 to improve the certainty that the positive bus bar 12a and the negative bus bar 12b are short-circuited at the time of collision.

  In the case 114, the rib 114b provided so as to surround the fragile portion 115 prevents a portion other than the fragile portion 115 from being greatly deformed by a load at the time of collision. By providing the rib 114b, the certainty that the fragile portion 115 separates from the groove 114a is further increased.

  In FIG. 5, sectional drawing of the power converter device 10b of a 2nd modification is shown. The power conversion device 10b of the second modified example is also mounted in the front compartment of the electric vehicle 90a, similarly to the power conversion device 10 of FIG. However, the power conversion device 10 b is fixed so as to be suspended from the frame member 21, and is disposed at a position lower than the previous power conversion device 10. Moreover, the power converter device 10b is being fixed to the frame member 21 in the front-down attitude | position. The upper surface of the casing 214 of the power conversion device 10b is also in a front-down posture. Since this power conversion device 10b is fixed at a low position and fixed in a forward-downward posture, it receives a load on the front surface and the upper surface of the housing 214 at the time of a forward collision. The protector 30 is attached to the front surface of the housing 214 via a robust support bracket 31 so that the front surface of the housing 214 is protected even when a load is applied from the front surface.

  On the other hand, a load guide member 222 is attached to the upper surface of the housing 214 via a flexible support bracket 23. As shown in FIG. 5, when a load W is received obliquely from the upper front during a collision, the support bracket 23 is deformed, and the load guiding member 222 moves downward. A weakened portion 215 is provided on the upper surface of the casing 214 of the power conversion device 10b. The fragile portion 215 is a region surrounded by the groove 214 a in the housing 214. When the casing 214 receives a load of a predetermined magnitude or more from above, it breaks at the bottom of the groove 214 a and the fragile portion 215 is detached from the casing 214. The portion of the load guide member 222 that faces the fragile portion 215 is provided with a protrusion 222a. When the load guide member 222 receives the load W and moves downward, the protrusion 222a loads the fragile portion 215 downward. . The fragile portion 215 is detached from the housing 214 due to the load and is pushed into the housing 214. Inside the casing 214, the positive electrode bus bar 12a and the negative electrode bus bar 12b are arranged close to the back surface of the fragile portion 215 (at a predetermined distance). The positive electrode bus bar 12 a and the negative electrode bus bar 12 b are connected to the smoothing capacitor 13 and transmit the power of the battery 2 to the smoothing capacitor 13 as in the case of the power converter 10 described above. When the conductive weak part 215 is pushed into the housing 214, the positive bus bar 12a and the negative bus bar 12b are in contact with the weak part 215, and both are short-circuited. The smoothing capacitor 13 is discharged by a short circuit between the positive electrode bus bar 12a and the negative electrode bus bar 12b.

  Similarly to the power conversion device 10 of the embodiment, the power conversion device 10a of the first modification and the power conversion device 10b of the second modification include a casing, a positive bus bar, and a negative bus bar that the power conversion device originally has. The smoothing capacitor 13 is discharged in the event of a collision. Also in the power converters 10a and 10b, the structure for discharging the smoothing capacitor 13 by the load at the time of collision can be realized at low cost.

  Points to be noted regarding the embodiment will be described. In order to more reliably short-circuit the positive electrode bus bar and the negative electrode bus bar when the fragile part is detached from the housing, the back surface of the fragile part is overlaid and the back surface of the fragile part and the bus bar (positive electrode bus bar and negative electrode bus bar) before detachment. It is also preferable to shorten the distance between

  The electric vehicle according to the embodiment corresponds to an example of “electric vehicle” in the claims. The technology disclosed in this specification is preferably applied to a hybrid vehicle and a fuel cell vehicle in addition to an electric vehicle.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Battery 3: System main relay 4: Voltage converter circuit 5: Inverter circuit 6: Motor for travel 7: Host controller 8: Airbag sensor 10, 10a, 10b: Power converter 12a: Positive bus bar 12b: Negative bus bar 13: Smoothing capacitors 14, 114, 214: Cases 14a, 114a, 214a: Grooves 15, 115, 215: Fragile portions 21: Frame members 22, 222: Load guiding members 22a, 222a: Protruding portions 23, 31: Support bracket 30: Protector 90, 90a: Electric vehicle 114b: Rib

Claims (1)

It is a power conversion device that is mounted on an electric vehicle and converts the power of the power source into the driving power of the traveling motor,
A smoothing capacitor that smoothes the current supplied from the power source, and a positive electrode bus bar and a negative electrode bus bar that transmit the power of the power source to the smoothing capacitor are provided inside the casing of the power converter.
The casing is provided with a fragile part that is detached from the inside of the casing when a load of a predetermined size or more is applied,
A part of the positive electrode bus bar and a part of the negative electrode bus bar are opposed to the back surface of the fragile part at a predetermined distance so that the weakened part that has been detached comes into contact with both the positive electrode bus bar and the negative electrode bus bar. The power converter.

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