JP2016220360A - Electric power conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power conversion system for facilitating work of fixing a discharge resistor element to a chiller during assembling.SOLUTION: The electric power conversion system includes: a pair of DC bus bar electrodes 21, 22, respectively connected to a positive electrode side and a negative electrode side of a DC power source; an electronic component 1, electrically connected to the pair of DC bus bar electrodes 21, 22; a discharge resistance element 4, for discharging charges accumulated in the electronic component 1; a chiller 5, being thermally in contact with the discharge resistance element 4; and a pair of metal bus bar electrodes 31, 32, disposed between the pair of DC bus bar electrodes 21, 22 and the discharge resistance element 4, for pressing the discharge resistance element 4 to the chiller 5 and fixing it.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device.

  A power conversion device applied to a vehicle such as an electric vehicle includes a smoothing capacitor for smoothing a current supplied from a DC power source and a discharge resistance element for discharging a charge accumulated in the smoothing capacitor. Provided. Since the discharge resistance element generates heat when discharging the electric charge accumulated in the smoothing capacitor, a cooler is provided in the vicinity of the discharge resistance element in order to remove the heat (see, for example, Patent Document 1).

JP 2015-237320 A

  As described in Patent Document 1, the discharge resistance element is electrically connected to the smoothing capacitor via a harness (electric wire) and a connection member (connection bus bar). However, since the harness (electric wire) is thin and soft at the time of assembly, it takes a lot of work time to fix the discharge resistance element to the cooler, and there is a problem that handling is difficult even in the case of automatic assembly by a robot.

  In view of the above problems, an object of the present invention is to provide a power conversion device that facilitates the work of fixing a discharge resistance element to a cooler during assembly.

  According to the power conversion device of one aspect of the present invention, a pair of metal bus bar electrodes are arranged between a pair of DC bus bar electrodes and a discharge resistance element, and the discharge resistance element is cooled by the pair of metal bus bar electrodes. It is characterized by being pressed against and fixed.

  ADVANTAGE OF THE INVENTION According to this invention, the power converter device which becomes easy the operation | work which fixes a discharge resistive element to a cooler at the time of an assembly can be provided.

It is sectional drawing which shows an example of the power converter device which concerns on the 1st Embodiment of this invention. It is a circuit diagram showing an example of a motor drive system to which a power converter concerning a 1st embodiment of the present invention is applied. It is a perspective view showing an example of a radiation resistor concerning a 1st embodiment of the present invention. FIG. 4A is a schematic diagram showing a temperature distribution around the radiation resistor according to the first embodiment of the present invention. FIG. 4B is a schematic diagram showing the temperature distribution around the heat dissipation resistor according to the comparative example. It is a perspective view which shows an example of the thermal radiation resistor which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the mode at the time of the thermal expansion of the thermal radiation resistor which concerns on the 2nd Embodiment of this invention. It is a front view which shows an example of the thermal radiation resistor which concerns on the 3rd Embodiment of this invention. It is a graph showing the power spectrum density waveform of the thermal radiation resistor which concerns on the 3rd Embodiment of this invention. FIG. 9A to FIG. 9C are front views respectively showing models A, B, and C of the radiation resistor according to the third embodiment of the present invention. It is a graph showing the relationship between the ratio of the height of a pair of metal bus bar electrodes to the distance between the fixed points of the pair of metal bus bar electrodes and the discharge resistance element according to the third embodiment of the present invention, and the natural frequency. is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same portions are denoted by the same reference numerals, and description thereof is omitted.

(First embodiment)
As shown in FIG. 1, the power converter according to the first embodiment of the present invention includes a pair of DC bus bar electrodes 21 and 22 connected to a positive electrode side and a negative electrode side of a DC power source (not shown), and a pair The discharge resistor 10 and the electronic component (smoothing capacitor) 1 electrically connected to the direct current bus bar electrodes 21 and 22 and the cooler 5 that is in thermal contact with the discharge resistor 10 are provided. In the present specification, the term “thermal contact” between the discharge resistor 10 and the cooler 5 means that the heat can be exchanged between the discharge resistor 10 and the cooler 5. It is not limited to the case where the resistor 10 and the cooler 5 are in direct mechanical contact, and includes a state in which a substance having high thermal conductivity such as heat-dissipating grease is interposed in the middle. In FIG. 1, the left and right direction toward the paper surface is described as the x-axis direction, the front-rear direction is the y-axis direction, and the vertical direction is the z-axis direction.

  The power conversion device according to the first embodiment of the present invention is an inverter that converts a DC power source into an AC power source, and can be applied to a motor drive system of a vehicle such as an electric vehicle as shown in FIG. The motor drive system shown in FIG. 2 includes a DC power supply 100, a smoothing capacitor 1 that smoothes the current of the DC power supply 100, and a discharge that discharges charges accumulated in the smoothing capacitor 1 when the ignition switch is turned off. A resistor 102, a plurality of semiconductor modules 111 to 116, a control circuit 104 for controlling the semiconductor modules 111 to 116, and a three-phase AC motor 103 driven by the semiconductor modules 111 to 116 are provided. Each of the plurality of semiconductor modules 111 to 116 includes a switching element 121 such as an insulated gate bipolar transistor (IGBT) and a protection diode 122.

  The smoothing capacitor 101 and the discharge resistor 102 shown in FIG. 2 correspond to the smoothing capacitor 1 and the discharge resistor 10 shown in FIG. 1, respectively. Note that the semiconductor modules 111 to 116 and the like shown in FIG. 2 are also arranged in the housing 7 shown in FIG. 1, but the illustration is omitted in FIG.

  As shown in FIG. 1, the discharge resistor 10 and the smoothing capacitor 1 are disposed in the housing 7. The opening at the top of the housing 7 is closed by a lid 6, and the lid 6 is fixed to the housing 7 by fixing tools 71 and 72 such as screws. The smoothing capacitor 1 is fixed to the housing 7 by fasteners 72 and 75 such as screws. The pair of DC bus bar electrodes 21 and 22 are fixed to the smoothing capacitor 1 by a fixing tool 74 such as a screw. The positional relationship within the housing 7 such as the discharge resistor 10 and the smoothing capacitor 1 is not particularly limited.

  The cooler 5 is formed integrally with the housing 7, and includes a cooling water channel 52 partitioned by the cooling fins 53 and a cooling plate 51 provided on the cooling fins 53. The cooler 5 may be a component independent of the housing 7. The cooler 5 cools heat (shown by arrows in FIG. 1) generated when the discharge resistor 10 discharges the electric charge accumulated in the smoothing capacitor 1 and discharges from the pair of DC bus bar electrodes 21 and 22. It also cools the heat transferred through the resistor 10 (shown by arrows in FIG. 1).

  One end of the pair of DC bus bar electrodes 21 and 22 extends outward from an opening provided in the lid 6 and is connected to a DC power supply (not shown). The pair of DC bus bar electrodes 21 and 22 are plate-like metal members as shown in FIGS. 1 and 3, and the DC power supply side extends parallel to each other in the z-axis direction and is bent at a right angle in the housing 7. Thus, the smoothing capacitor 1 extends parallel to each other in the x-axis direction.

  As shown in FIGS. 1 and 3, the discharge resistor 10 includes a discharge resistor element 4 covered with an insulator for discharging charges accumulated in the smoothing capacitor 1, and a pair of DC bus bar electrodes 21 and 22. And a pair of metal bus bar electrodes 31, 32 connecting the discharge resistance element 4. The pair of metal bus bar electrodes 31 and 32 is a rigid body made of a plate-like metal material such as copper or aluminum. In this specification, the “rigid body” is distinguished from a harness or the like that cannot press the discharge resistance element 4 against the cooler 5 and has a rigidity that can press the discharge resistance element 4 against the cooler 5. Means solid. For example, the height of the pair of metal bus bar electrodes 31 and 32 is about 150 mm, the width is about 15 mm, and the thickness is about 1 mm.

  The pair of metal bus bar electrodes 31 and 32 are in contact with the discharge resistance element 4 at one end, and are bent from the main body portions 31a and 32a extending in the z-axis direction and the other end of the main body portions 31a and 32a, and are mutually connected in the y-axis direction. And connection portions 31b and 32b extending inward. For example, the main body portions 31 a and 32 a are fixed to the discharge resistance element 4 by pressure contact. On the other hand, the connecting portions 31b and 32b may be fixed to the pair of DC bus bar electrodes 21 and 22 by pressure welding or welding, or may be fixed to the pair of DC bus bar electrodes 21 and 22 by a fixing tool such as a screw. . In order to increase the contact area between the pair of DC bus bar electrodes 21 and 22, the connection portions 31b and 32b are preferably provided. However, the connection portions 31b and 32b are not provided, and the other end of the main body portions 31a and 32a is a pair of direct currents. The bus bar electrodes 21 and 22 may be fixed.

  The discharge resistance element 4 is disposed on the cooling plate 51 of the cooler 5. It is preferable that at least a part of the discharge resistance element 4 is in direct contact (pressure contact) with the cooling plate 51 of the cooler 5. In addition, the discharge resistance element 4 may be arrange | positioned through the thermal radiation grease etc. on the cooling plate 51. FIG. Here, the center C1 of the connection portion between the pair of DC bus bar electrodes 21 and 22 and the connection portions 31b and 32b of the pair of metal bus bar electrodes 31 and 32 and the center of gravity C2 of the discharge resistance element 4 are orthographic projection planes ( It is preferable that they substantially coincide with each other when viewed from the z-axis direction).

  In an example during assembly of the power conversion device according to the first embodiment of the present invention, first, the pair of DC bus bar electrodes 21, 22 and the connection portions 31b, 32b of the pair of metal bus bar electrodes 31, 32 are mutually connected. After fixing, the discharge resistance element 4 is fixed on the cooler 5 by pressing the main body portions 31 a and 32 a side against the discharge resistance element 4 disposed on the cooler 5. At this time, since the pair of metal bus bar electrodes 31 and 32 and the discharge resistance element 4 are connected to each other by a rigid body, the discharge resistance element 4 can be pressed against the cooler 5 and fixed. Therefore, the work becomes easier compared to the case where the pair of DC bus bar electrodes 21 and 22 and the discharge resistance element 4 are connected by a thin and soft harness, and the work time required to fix the discharge resistance element 4 to the cooler 5 is reduced. It can be shortened. Further, in the case of automatic assembly by a robot, since a set of a pair of DC bus bar electrodes 21 and 22 and a pair of metal bus bar electrodes 31 and 32 may be pressed against the discharge resistance element 4, handling is easy. Become.

  Moreover, since the discharge resistance element 4 can be pressed against the cooler 5 as compared with the case where the pair of DC bus bar electrodes 21 and 22 and the discharge resistance element 4 are connected with a thin and soft harness, the cooling effect is improved. The temperature rise of the discharge resistance element 4 can be further reduced.

  In this regard, FIG. 4A shows a measurement result of the temperature distribution when the metal bus bar electrode 31 according to the embodiment of the present invention is used, and FIG. 4B shows a metal bus bar electrode as a comparative example. The measurement result of the temperature distribution at the time of using the harness 31x instead of 31 is shown. 4A, the temperature of the DC bus bar electrode 21 is 66.5 ° C., the temperature of the cooler 5 is 48 ° C., the loss of the DC bus bar electrode 21 is 11 W, the loss of the metal bus bar electrode 31 is 0 W, and the discharge. The loss of the resistance element 4 is 2.7 W.

  On the other hand, in the comparative example of FIG. 4B, the temperature of the DC bus bar electrode 21 is 80.5 ° C., the temperature of the cooler 5 is 48 ° C., the loss of the DC bus bar electrode 21 is 11 W, and the loss of the harness 31x is The loss of 0 W and the discharge resistance element 4 is 2.7 W. From FIG. 4A and FIG. 4B, the direct current bus bar electrode 21 is better when the metal bus bar electrode 31 according to the embodiment of the present invention is used than when the comparative example shown in FIG. It can be seen that the temperature is reduced by 14 ° C.

  According to the first embodiment of the present invention, a pair of metal bus bar electrodes 31, 32 are arranged between the pair of DC bus bar electrodes 21, 22 and the discharge resistance element 4, and the pair of metal bus bar electrodes 31, By pressing and fixing the discharge resistance element 4 to the cooler 5 by 32, the working time can be shortened as compared with the case where a soft part such as a harness is assembled, and automatic assembly using a robot is also possible. It becomes easy and the production cost can be reduced.

  Further, by connecting the smoothing capacitor 1 as an electronic component to the pair of DC bus bar electrodes 21 and 22, the electric charge accumulated in the smoothing capacitor 1 is discharged by the discharge resistor 10 and is generated in the smoothing capacitor 1. Heat can be dissipated through the discharge resistor 10.

  Further, when at least a part of the discharge resistance element 4 is in direct contact with the cooler 5, the cooling effect is improved, and the pair of DC bus bar electrodes 21 and 22, the pair of metal bus bar electrodes 31 and 32, and the discharge, The temperature rise of the resistance element 4 can be reduced. Therefore, the internal atmospheric temperature of the housing 7 can be reduced, and the plate thickness of the pair of DC bus bar electrodes 21 and 22 and the pair of metal bus bar electrodes 31 and 32 can be reduced, thereby reducing the component cost and weight. be able to.

  Further, the center C1 of the connection portion between the pair of DC bus bar electrodes 21 and 22 and the connection portions 31b and 32b of the pair of metal bus bar electrodes 31 and 32 and the center of gravity C2 of the discharge resistance element 4 are seen from the orthographic projection plane. By substantially matching, when the pair of metal bus bar electrodes 31 and 32 are pressed against the discharge resistance element 4 at the time of assembly, the discharge resistance element 4 is easily fixed, and the assembling work becomes easier.

(Second Embodiment)
As shown in FIG. 5, the power converter according to the second embodiment of the present invention is provided with one bending point P <b> 1, P <b> 2 on each of the pair of metal bus bar electrodes 31, 32 of the discharge resistor 10. This is different from the power converter according to the first embodiment of the present invention. Since the other structure of the power converter device which concerns on the 2nd Embodiment of this invention is the same as that of the power converter device which concerns on the 1st Embodiment of this invention, the overlapping description is abbreviate | omitted.

  FIG. 5 shows a case where one bending point P1, P2 is provided in each of the main body portions 31a, 32a of the pair of metal bus bar electrodes 31, 32, but the bending points P1, 1 provided in the main body portions 31a, 32a are shown. The number of P2 is not limited. For example, two or more bending points may be provided in each of the main body portions 31a and 32a of the pair of metal bus bar electrodes 31 and 32. The angle at which the body portions 31a, 32a of the pair of metal bus bar electrodes 31, 32 are bent with respect to the y-axis direction by the bending points P1, P2 can be set as appropriate. In FIG. 5, the main body portions 31a and 32a are bent inward, but may be bent outward.

  As shown in FIG. 6, the heat from the smoothing capacitor 1 via the discharge resistor element 4 or the pair of DC bus bar electrodes 21 and 22 causes the pair of metal bus bar electrodes 31 and 32 to thermally expand to form a spring structure. . For this reason, the discharge resistance element 4 can be strongly pressed against the cooler 5. In addition, in FIG. 6, the pressing reaction force by thermal expansion is typically shown with an arrow. Furthermore, by providing the bending points P1 and P2 on a part of the pair of metal bus bar electrodes 31 and 32, the bending points P1 and P2 can absorb the thermal stress and relieve the stress.

  According to the second embodiment of the present invention, a pair of metal bus bar electrodes 31, 32 between the pair of DC bus bar electrodes 21, 22 and the discharge resistance element 4, as in the first embodiment of the present invention. And the discharge resistance element 4 is pressed against and fixed to the cooler 5 by the pair of metal bus bar electrodes 31 and 32, so that the working time is shortened as compared with the case where a soft part such as a harness is assembled. In addition, automated assembly using a robot is facilitated, and production costs can be reduced.

  Further, according to the second embodiment of the present invention, the discharge resistance element 4 is connected to the cooler 5 by providing one or more bending points P1 and P2 on a part of the pair of metal bus bar electrodes 31 and 32. While being able to press strongly, the bending points P1 and P2 can absorb thermal stress and relieve stress. Furthermore, vibration stress can be relieved, and the in-vehicle vibration resistance of the inverter fixed to the vehicle body mount and the drive motor can be improved.

(Third embodiment)
As shown in FIG. 7, the power converter according to the third embodiment of the present invention includes a height H of a pair of metal bus bar electrodes 31, 32, a pair of metal bus bar electrodes 31, 32, and a discharge resistance element. And the distance between the fixed points of 4 (in other words, the width in the direction in which the pair of metal bus bar electrodes 31 and 32 are arranged (y-axis direction)) W satisfies the following expression (1). This is different from the second embodiment of the present invention.

H <W × 3.5 (1)

  That is, the ratio of the height H of the pair of metal bus bar electrodes 31, 32 to the distance W between the fixed points of the pair of metal bus bar electrodes 31, 32 and the discharge resistance element 4 is set to less than 350%. For example, by defining the height H of the pair of metal bus bar electrodes 31 and 32 as 148 mm and the distance W between the fixed points of the pair of metal bus bar electrodes 31 and 32 and the discharge resistance element 4 as 42 mm, the ratio W / H is 236%. Since the other structure of the power converter device which concerns on the 3rd Embodiment of this invention is the same as that of the power converter device which concerns on the 2nd Embodiment of this invention, the overlapping description is abbreviate | omitted.

  FIG. 8 shows a power spectral density (PSD) waveform representing the input vibration from the vehicle in the engine room where the inverter is mounted. The horizontal axis of FIG. 8 shows the vibration frequency of the inverter, and the vertical axis shows the amplitude received from the vehicle. In the PSD waveform shown in FIG. 8, the component mounted in the engine room has a very small amplitude if the vibration frequency is 100 Hz or more. For this reason, as for the component in an inverter, it is desirable for an eigenvalue to be 100 Hz or more.

  Here, in FIG. 9A to FIG. 9C, the distance W between the fixed points of the pair of metal bus bar electrodes 31 and 32 and the discharge resistance element 4 is fixed at 42 mm, and the pair of metal bus bar electrodes. Models A, B, and C of the discharge resistor 10 in which the heights H of 31 and 32 are changed to 15 mm, 40 mm, and 148 mm are shown. In models A, B, and C of FIGS. 9A to 9C, the pair of metal bus bar electrodes 31 with respect to the distance W between the fixed points of the pair of metal bus bar electrodes 31 and 32 and the discharge resistance element 4. 32, the ratio H / W of the height H is 35%, 94% and 236%, respectively.

  FIG. 10 shows the ratio H / W of the height H of the pair of metal bus bar electrodes 31, 32 to the distance W between the fixed points of the pair of metal bus bar electrodes 31, 32 and the discharge resistance element 4, and the natural frequency. Show correlation. As shown in FIG. 10, the ratio of the height H of the pair of metal bus bar electrodes 31, 32 to the distance W between the fixed points of the pair of metal bus bar electrodes 31, 32 and the discharge resistance element 4 is less than 350%. By doing so, it is possible to achieve a natural frequency of 100 Hz or more that can avoid resonance with respect to vibration input from the vehicle.

  According to the third embodiment of the present invention, as in the first and second embodiments of the present invention, a pair of metal bus bar electrodes 31 between the pair of DC bus bar electrodes 21, 22 and the discharge resistance element 4. 32, and the discharge resistance element 4 is pressed against the cooler 5 by the pair of metal bus bar electrodes 31 and 32 and fixed to the cooler 5, thereby shortening the working time as compared with the case where a soft part such as a harness is assembled. In addition, automatic assembly using a robot is facilitated, and production costs can be reduced.

  Similarly to the second embodiment of the present invention, one or more bending points P1 and P2 are provided on a part of the pair of metal bus bar electrodes 31 and 32, whereby the discharge resistance element 4 is connected to the cooler 5. While being able to press strongly, the bending points P1 and P2 can absorb thermal stress and relieve stress. Furthermore, vibration stress can be relieved, and the in-vehicle vibration resistance of the inverter fixed to the vehicle body mount and the drive motor can be improved.

  Further, according to the third embodiment of the present invention, the height H of the pair of metal bus bar electrodes 31, 32 with respect to the distance W between the fixed points of the pair of metal bus bar electrodes 31, 32 and the discharge resistance element 4. By making the ratio of less than 350%, it can be optimized so as not to resonate with respect to vehicle vibration input, and a desired in-vehicle resistance can be obtained.

(Other embodiments)
As described above, the first to third embodiments of the present invention have been described. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the shape of the pair of metal bus bar electrodes 31 and 32 is not particularly limited as long as the discharge resistance element 4 can be pressed against the cooler 5. For example, FIG. 3 shows the case where the connection portions 31b and 32b of the pair of metal bus bar electrodes 31 and 32 extend inward, but they may extend outward.

  In the first to third embodiments of the present invention, the case where the electronic component 1 is a smoothing capacitor has been described, but the electronic component 1 may be another component.

1,101 ... Electronic component (smoothing capacitor)
DESCRIPTION OF SYMBOLS 4 ... Discharge resistance element 5 ... Cooler 6 ... Cover 10 ... Discharge resistor 21, 22 ... DC bus bar electrode 31, 32 ... Metal bus bar electrode 51 ... Cooling plate 52 ... Cooling water channel 53 ... Cooling fins 71-75 ... Fixing tool DESCRIPTION OF SYMBOLS 100 ... DC power supply 102 ... Discharge resistor 103 ... Three-phase AC motor 104 ... Control circuit 111-116 ... Semiconductor module 121 ... Switching element 122 ... Protection diode

Claims (6)

A pair of DC bus bar electrodes respectively connected to the positive electrode side and the negative electrode side of the DC power source;
Electronic components electrically connected to the pair of DC bus bar electrodes;
A discharge resistance element for discharging the electric charge accumulated in the electronic component;
A cooler in thermal contact with the discharge resistance element;
A power conversion device comprising: a pair of metal bus bar electrodes arranged between the pair of DC bus bar electrodes and the discharge resistance element and pressing the discharge resistance element against the cooler to fix the same.   The power converter according to claim 1, wherein each of the pair of metal bus bar electrodes has a bending point.   3. The ratio of the height of the pair of metal bus bar electrodes to the distance between the fixed points of the pair of metal bus bar electrodes and the discharge resistance element is less than 350%. Power converter.   The power converter according to claim 1, further comprising a smoothing capacitor electrically connected to the pair of DC bus bar electrodes.   The power converter according to any one of claims 1 to 4, wherein the discharge resistance element and the cooler are in direct contact.   The center of the connection portion between the pair of metal bus bar electrodes and the pair of DC bus bar electrodes and the center of gravity of the discharge resistance element substantially coincide when viewed from the orthographic projection plane. The power converter according to any one of 5.

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