JP2009038842A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter for reducing pressure loss while maintaining cooling performance. <P>SOLUTION: The power converter has a plurality of switching elements for converting DC current supplied from a battery into three-phase AC current; a drive control circuit for controlling the operation of each of the plurality of switching elements; a coolant passage for flowing a coolant for cooling the switching elements from the upstream to the downstream; a base having the plurality of switching elements disposed from the upstream side to the downstream side of the coolant passage on one surface; a plurality of fins provided on the base so as to be immersed in the coolant on a surface opposite to the one surface; and a capacitor for smoothing a DC voltage supplied from the battery. The power converter is configured so as to dispose the plurality of fins more densely from the upstream side to the downstream side of the coolant path. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power conversion device having a structure for cooling by flowing a fluid, and more particularly to a power conversion device used for an electric vehicle.

  Semiconductor devices such as MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) are mounted on the power conversion device for switching and rectification. In order to cool these semiconductor elements, the power converter is provided with a flow path through which a cooling medium flows.

  A plurality of fins serving as heat sinks for cooling the semiconductor elements are provided on the surface of the flow path on the semiconductor element side. These fins are generally formed with the same height, the same pitch, and the same number of fins from the upstream to the downstream of the flow path.

  For example, a structure using straight fins is disclosed in Japanese Patent Application Laid-Open No. 2004-349324 (Patent Document 1). In the case where the fin is a pin fin, as shown in FIG. 5, the pin fins having the same shape are generally standing at a uniform pitch over the entire flow path.

JP 2004-349324 A

  Normally, fins are arranged at the same height, the same pitch, and the same quantity from the inlet to the outlet of the flow path. In this case, a plurality of semiconductor elements are arranged in series on the surface of the heat sink opposite to the fin formation surface in the same direction as the flow path of the refrigerant. If these semiconductor elements generate the same amount of heat on average, the upstream elements are cooled better than the downstream elements.

  When trying to suppress the temperature rise of the downstream side semiconductor element affected by the upstream side heat, the upstream side semiconductor element is cooled more than necessary, but the upstream side causes unnecessary pressure loss. become. Generally, the heat transfer rate is improved when the pressure loss is high. However, a lower pressure loss is desirable. For this reason, it is desirable to reduce the pressure loss that can be reduced as much as possible.

  In order to solve the above-mentioned problem, a representative one of the power conversion devices of the present invention includes a plurality of switching elements (IGBT, MOSFET, etc.) for converting a direct current supplied from a battery into a three-phase alternating current. A drive control circuit for controlling the operation of the plurality of switching elements, a refrigerant passage for flowing the refrigerant from the upstream side to the downstream side to cool the switching elements, and on one side, from the upstream side to the downstream side of the refrigerant passage Smoothes the DC voltage supplied from the battery, the base with a plurality of switching elements arranged in the direction, the plurality of fins provided on the base so as to be immersed in the refrigerant on the surface opposite to the one surface And the arrangement density of the plurality of fins is configured to increase from the upstream side to the downstream side of the refrigerant passage. And butterflies.

  The present invention can provide a power conversion device with reduced pressure loss while ensuring cooling performance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 10 is a configuration diagram showing an embodiment of a hybrid electric vehicle provided with the power conversion device of the present invention. In addition, although the power converter device 200 by this invention can be applied to a pure electric vehicle and a hybrid type electric vehicle, the example of a hybrid type electric vehicle is demonstrated as a representative below.

  The hybrid electric vehicle 100 includes an engine 120, a first rotating electrical machine 130, a second rotating electrical machine 140, and a battery 180 that supplies high-voltage DC power to the first rotating electrical machine 130 and the second rotating electrical machine 140. Is installed. Further, a battery for supplying low voltage power (14 volt system power) is mounted, and DC power is supplied to a control circuit described below, but the illustration is omitted.

  The rotational torque based on the engine 120, the first rotating electrical machine 130, and the second rotating electrical machine 140 is transmitted to the transmission 150 and the differential gear 160, and is transmitted to the front wheels 110.

  A transmission control device 154 for controlling the transmission 150, an engine control device 124 for controlling the engine 120, a rotating electrical machine control circuit for the rotating electrical machine control circuit board 700 for controlling the power converter 200, and a battery 180 such as a lithium ion battery are controlled. The battery control device 184 and the integrated control device 170 are connected by a communication line 174, respectively.

  The integrated control device 170 receives information representing the respective states from the transmission control device 154, the engine control device 124, the power conversion device 200, and the battery control device 184, which are lower-order control devices, via the communication line 174. . Based on these pieces of information, the control command of each control device is calculated by the integrated control device 170, and the control command from the integrated control device 170 to each control device is transmitted to each control device via the communication line 174.

  For example, the battery control device 184 reports the discharge status of the battery 180, which is a lithium ion battery, and the status of each unit cell battery constituting the lithium ion battery to the integrated control device 170 as the status of the battery 180. When the integrated control device 170 determines from the above report that the battery 180 needs to be charged, the integrated control device 170 instructs the power conversion device 200 to perform a power generation operation.

  The integrated control device 170 manages the output torque of the engine 120 and the first and second rotary electricity 130 and 140. The integrated control device 170 calculates the total torque or torque distribution ratio of the output torque of the engine and the first and second rotating electrical machines 130 and 140, and gives a control command based on the processing result to the transmission control device 154 and the engine control. The data is transmitted to the device 124 and the power conversion device 200. Based on the torque command, the power conversion device 200 controls the first rotating electrical machine 130 and the second rotating electrical machine 140, and generates the torque output of the command or generated power in either one or both rotating electrical machines. Thus, these rotating electrical machines are controlled.

  The power conversion device 200 operates the first rotating electrical machine 130 and the second rotating electrical machine 140 based on a command from the integrated control device 170. For this reason, the switching operation of the power semiconductor constituting the inverter is controlled. By the switching operation of these power semiconductors, the first rotating electrical machine 130 and the second rotating electrical machine 140 are operated as an electric motor or a generator.

  When operating as an electric motor, DC power from the high-voltage battery 180 is applied to the inverter of the power converter 200. This direct current power is converted into a three-phase alternating current by a switching operation of a power semiconductor constituting the inverter. The three-phase alternating current is supplied to the rotating electrical machine 130 or 140.

  On the other hand, when operated as a generator, the rotor of the rotating electrical machine 130 or 140 rotates with external rotational torque, and three-phase AC power is generated in the stator winding of the rotating electrical machine based on this rotational torque. The generated three-phase AC power is converted into DC power by the power converter 200. The DC power is supplied to the high-voltage battery 180, and the battery 180 is charged.

  As shown in FIG. 10, the power conversion device 200 includes a capacitor module 300 having a plurality of smoothing capacitors that suppresses voltage fluctuations of a DC power supply, a power module 500 incorporating a plurality of power semiconductors, and a switching operation of the power module 500. Rotating electrical machine control circuit including a switching drive circuit board 600 having a switching drive circuit for controlling the rotation, and a rotating electrical machine control circuit for generating a signal for determining a time width of the switching operation, that is, a PWM signal for controlling pulse-wide modulation A substrate 700 is used.

  The high voltage battery 180 is a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The battery 180 outputs high-voltage DC power of 250 to 600 volts or more.

  FIG. 6 is an exploded perspective view of the power conversion device 200 described above, and schematically shows the overall configuration of the power conversion device 200. FIG. 7 is an external view of the power conversion device 200.

  The power conversion device 200 includes a housing 210 having a box shape, and a water channel forming body 220 having a coolant passage 216 through which cooling water circulates is provided at the bottom of the housing 210. An inlet pipe 212 and an outlet pipe 214 for supplying cooling water to the refrigerant passage 216 protrude to the outside of the housing 210 at the bottom of the housing 210. The water channel formation body 220 has a function as a cooling passage formation body that forms a cooling passage. In this embodiment, engine coolant is used as the refrigerant.

  In the power conversion device 200 of the present embodiment, two power modules 500 shown in FIG. 10 are used. Specifically, as shown in FIG. 6, the power conversion device 200 includes a first power module 502 and a second power module 504 that are arranged in parallel in the housing 210. The first power module 502 and the second power module 504 are provided with heat radiation fins 506 and 507 for cooling, respectively.

  On the other hand, the water channel formation body 220 is provided with openings 218 and 219. By fixing the first and second power modules 502 and 504 to the water passage forming body 220, the cooling fins 506 and 507 protrude into the refrigerant passage 216 from the openings 218 and 219, respectively. The openings 218 and 219 are closed with metal walls around the heat radiation fins 506 and 507 to form a cooling water channel, and the openings are closed so that the cooling water does not leak.

  The first and second power modules 502 and 504 are arranged on the left and right sides of a virtual line segment orthogonal to the side wall surface of the housing 210 where the cooling water inlet pipe 212 and the cooling water outlet pipe 214 are formed. Has been placed. The cooling water channel formed inside the water channel forming body 220 extends from the cooling water inlet pipe 212 to the other end along the longitudinal direction of the housing bottom, is folded back in a U-shape at the other end, and again is the longitudinal length of the housing bottom. Along the direction extends to the outlet pipe 214.

  Two sets of parallel water channels along the longitudinal direction are formed in the water channel forming body 220, and the water channel forming body 220 is formed with the openings 218 and 219 having a shape penetrating the water channels. The first power module 502 and the second power module 504 are fixed to the water channel formation body 220 along the passage. The radiation fins provided in the first and second power modules 502 and 504 project into the water channel, so that the cooling is efficiently performed. In addition, since the heat dissipation surfaces of the first and second power modules 502 and 504 are in close contact with the metal water channel formation body 220, an efficient heat dissipation structure can be realized. Furthermore, since the openings 218 and 219 are respectively closed by the heat radiation surfaces of the first and second power modules 502 and 504, the structure is reduced in size and the cooling effect is improved.

  The first drive circuit board 602 and the second drive circuit board 604 are arranged in parallel by being stacked on the first power module 502 and the second power module 504, respectively. The first drive circuit board 602 and the second drive circuit board 604 constitute the switching drive circuit board 600 described with reference to FIG.

  The first drive circuit board 602 disposed above the first power module 502 is formed slightly smaller than the first power module 502 when viewed in plan. Similarly, the second drive circuit board 604 disposed above the second power module 504 is also formed slightly smaller than the second power module 504 when viewed in plan.

  An inlet pipe 212 and an outlet pipe 214 for cooling water are provided on the side surface of the housing 210, and a hole 260 is further formed on the side surface, and a signal connector 282 is disposed in the hole 260. A noise removal board 560 and a second discharge board 520 that are fixed in the vicinity of the signal connector 282 are disposed inside the housing 210 at a position where the connector 282 is attached. The attachment surfaces of the noise removal substrate 560 and the second discharge substrate 520 are attached so as to be parallel to the attachment surfaces of the first power module 502, the second power module 504, and the like.

  A capacitor module 300 having a plurality of smoothing capacitors is disposed above the plurality of drive circuit boards 602 and 604. The capacitor module 300 includes a first capacitor module 302 and a second capacitor module 304. The first capacitor module 302 and the second capacitor module 304 are disposed above the first drive circuit board 602 and the second drive circuit board 604, respectively.

  Above the first capacitor module 302 and the second capacitor module 304, a flat plate-like holding plate 320 is disposed with its periphery closely attached to the inner wall surface of the housing 210. The holding plate 320 supports the first capacitor module 302 and the second capacitor module 304 on the surface on the power module side, and holds and fixes the rotating electrical machine control circuit board 700 on the opposite surface. Yes. The holding plate 320 is made of a metal material, and the heat generated by the capacitor modules 302 and 304 and the rotating electrical machine control circuit board 700 is passed through the housing 210 to radiate heat.

  As described above, the power module 500, the switching drive circuit board 600, the noise removal board 560, the second discharge board 520, the capacitor module 300, the holding plate 320, and the rotating electrical machine control circuit board 700 are housed in the housing 210. The upper opening of the housing 210 is closed by a metal cover 290.

  Further, when the side wall of the housing 210 where the cooling water inlet pipe 212 and the outlet pipe 214 are provided is the front, the terminal box 800 is attached to the side wall. In the terminal box 800, a DC power terminal 812 for supplying DC power from the battery 180, a DC power terminal block 810 provided therein, the first rotating electrical machine 130, and the second rotation are provided. An AC power terminal 822 connected to the electric machine 140 and an AC terminal block 820 provided therein are provided.

  The DC power terminal block 810 is electrically connected to the electrodes of the first capacitor module 302 and the second capacitor module 304 via a bus bar, and the AC terminal block 820 includes a plurality of power modules 500. The terminals of the power modules 502 and 504 are electrically connected to each other via bus bars.

  The terminal box 800 is configured by attaching a bottom plate portion 844 and a cover portion 846 in which a DC power terminal block 810 is disposed on the main body 840. This is to facilitate assembly of the terminal box 800.

  Moreover, the power converter device 200 has a compact shape as shown in FIG.

  As described above, the refrigerant passage 216 is formed at the bottom of the power conversion device 200. FIG. 8 is a structural view of the housing 210 as viewed from the bottom, and shows a water channel holding member 902 that is a part of the water channel forming body 220. The water channel holding member 902 has an outer peripheral portion 904 for attaching a bottom plate 934, which is another water channel forming body 220, and the outer peripheral portion 904 is provided with a number of screw holes SC9. Only a part of the symbols are attached, and the others are omitted.

  A seal groove 906 for preventing water leakage is provided on the inner side of the outer peripheral part 904. The water channel holding member 902 on the inner side of the seal groove 906 is provided with outer region parts 912 on both sides. Water channels 922 and 924 and a central portion 908 are provided. A seal member such as an O-ring or rubber is fitted in the seal groove 906 and sealed by tightening the screw hole SC9 with a screw.

  Cooling water is supplied to the inlet 916 of the water channel 922 (previously described as the refrigerant passage 216), the cooling water flows in the direction of the arrow through the first water channel 922, and the flow of the cooling water is U-shaped in the return passage 924. Instead, it flows through the second water channel 924 in the direction of the arrow, and is discharged from the outlet 918 of the water channel 924. The first and second water channels 922 and 924 are provided with openings 218 and 219 which are holes. By attaching a bottom lid (not shown), water channels 922 and 924 are formed.

  A central portion 908 provided between the first water passage 922 and the second water passage 926, and a portion between the first water passage 922 and the outer peripheral portion 904 and between the second water passage 926 and the outer peripheral portion 904. Each of the outer region portions 912 is provided with a recess 932 for reducing the thickness of the aluminum die cast.

  FIG. 9 is an external view of a power module 500 used in this embodiment.

  In the power module 500, a plurality of IGBTs and MOSFETs which are switching elements are arranged on a base 2 made of a metal such as copper. These switching elements are covered with a resin case 17.

  The resin case 17 is provided with a plurality of DC terminals IT1P, IT1N and AC terminals OT1u, OT1v, OT1w at the upper part thereof. Further, a plurality of control terminals CT protrude from the resin case 17.

  The DC terminal IT1P on the positive side and the DC terminal IT1N on the negative side are connected to the battery 180. The direct current output from the battery 180 is supplied to the switching element via the direct current terminals IT1P and IT1N. The switching element is on / off controlled based on a control signal output from the switching drive circuit board 600 to the control terminal CT. The direct current supplied from the battery 180 is converted into a three-phase alternating current by ON / OFF control of a plurality of switching elements. The converted three-phase alternating current is output as the U-phase, V-phase, and W-phase from the AC terminals OT1u, OT1v, and OT1w, respectively, and used to drive the rotating electrical machines 130 and 140.

  An internal plan view of the power module 500 with the resin case 17 removed is shown in FIG. 1A, and a back plan view of the power module 500 is shown in FIG.

  In FIG. 1A, three sets of semiconductor chips bonded to each insulating substrate 15 constitute a semiconductor element group 5 and are composed of an IGBT chip 13 and a diode chip 14. These semiconductor chips are bonded to the insulating substrate 15. Three IGBT chips 13 and three diode chips 14 are bonded to each insulating substrate 15 with high-temperature solder. Further, six insulating substrates 15 having these six semiconductor chips are bonded to the base 2 with low temperature solder in the arrangement shown in FIG. For each semiconductor chip mounted on the two insulating substrates 15, U-phase, V-phase, and W-phase arms are formed, and the semiconductor chips on these two insulating substrates 15 respectively constitute an upper arm and a lower arm. The semiconductor element group 5 mounted on each insulating substrate 15 has the same calorific value on average.

  In this embodiment, the IGBT chip 13 is used as the semiconductor chip, but a MOSFET chip may be used instead of the IGBT chip. In this case, the diode chip 14 can be omitted.

  As shown in FIG. 1B, pin-shaped fins 1 are formed on the back surface of the base 2 on which the semiconductor element group 5 is mounted.

  The pitch (distribution density) of the fins 1 changes along the direction in which the cooling water flows in the refrigerant passage 216. In this embodiment, the density of the fins 1 on the upstream side of the refrigerant passage 216 is rough, and the fins 1 on the downstream side are arranged densely. By arranging the density of the fins 1 on the upstream side to be coarser than that on the downstream side, the pressure loss on the upstream side can be reduced while effectively cooling the semiconductor element group 5 on the downstream side. That is, it is possible to reduce the pressure loss of the entire heat sink while ensuring the cooling performance for the semiconductor chip that is at the highest temperature.

  The fin density in FIG. 1B changes in three stages from upstream to downstream of the refrigerant passage 216, but is not particularly limited to such a configuration. The configuration may be changed in two stages or four or more stages from upstream to downstream. Moreover, it can also be set as the structure where a fin density changes continuously from upstream to downstream.

  This fin arrangement is designed to be optimal at a certain flow rate, and is provided with a pump, a fan, etc. (not shown) controlled so as to always give an optimal constant flow rate regardless of the water temperature. . These pumps, fans, and the like may be provided inside the power conversion apparatus 200 or may be arranged outside.

  FIG. 2 shows the thermal analysis result per power module. As the shape of the heat sink, a case where the fin density is constant as in the prior art and a case where the density is changed on the upstream side and the downstream side of the refrigerant passage 216 as shown in FIG. 1 are compared. The comparison is made with the maximum temperature of the IGBT chip and the comparison with the pressure loss in the entire heat sink.

  When the conventional structure and the structure of the present embodiment are compared, the pressure loss of the heat sink of the present embodiment is reduced by 30% or more compared to the conventional structure, although the temperature rise of the IGBT chip is equivalent. Further, the number of fins 1 is smaller on the upstream side than on the downstream side of the refrigerant passage 216. For example, in this embodiment, the number of pins of the fin 1 can be reduced by about 2.5% compared to the conventional case, and the cost is reduced accordingly.

  In this embodiment, the fins 1 are arranged so as to change the pitch (density). However, instead of this, the height of the fins 1 between the upstream side and the downstream side may be changed. It is possible to obtain the effect of reducing the pressure loss of the entire heat sink while ensuring the cooling performance for the semiconductor chip that becomes high temperature. When changing the height of the fin 1, the fin 1 on the upstream side of the refrigerant passage 216 is lowered and the fin 1 on the downstream side is raised. Moreover, it can also be set as the structure which changes both the pitch (density) and height of the fin 1. FIG.

  In this embodiment, cylindrical pin fins are used, but other pin fin shapes such as a quadrangular prism and a triangular prism can also be employed. In addition, in the fin shape other than the pin fin, by changing the height and pitch (density) of the fin, the pressure loss can be reduced while ensuring the cooling performance as in the case of the pin fin. Obtainable.

  3A and 3B show an example in which straight fins are used instead of pin fins. FIG. 3A shows the relationship between the arrangement of the semiconductor element group 5, the direction of the cooling water, and the change in fin pitch.

  The interval between adjacent straight fins is narrower on the downstream side of the refrigerant passage 216 than on the upstream side. In other words, the number of straight fins on the downstream side is larger than the number on the upstream side. In the present embodiment, the fin pitch of the straight fin is divided into three stages. However, the configuration is not limited to this, and a configuration other than the division into three steps may be adopted. In addition, the straight fin is parted in the location which changes in steps. Thus, even when straight fins are employed, it is possible to obtain an effect that pressure loss can be reduced while ensuring cooling performance.

  FIG. 3B shows a schematic diagram of a cross-sectional structure cut along XY in FIG.

  This figure shows a direct cooling system structure in which fins 1 are directly attached to a base 2 made of a metal such as copper, and then cooled. However, instead of this, as shown in FIG. 4, a configuration in which the refrigerant passage 216 and the fins 1 are provided in the casing 21 made of metal such as aluminum may be employed. The refrigerant passage 216 is formed by fixing the bottom cover 22 to the housing 21. Further, the semiconductor chip is indirectly cooled by arranging the base 2 and the semiconductor chip on the housing 21. Such a configuration is referred to as an indirect water-cooled power converter.

  As mentioned above, according to the said Example, while reducing the pressure loss in the upstream of cooling water, the minimum heat transfer rate for cooling a semiconductor chip is securable. As a result, it is possible to provide a power conversion device that has a cooling performance equivalent to that of the prior art and achieves a lower pressure loss.

(A) It is an internal top view of a power module, (b) It is a back surface top view of a power module. It is a figure which shows the thermal analysis result of a power module. It is a figure of the power converter device at the time of using a straight fin. It is sectional drawing in XY of Fig.3 (a). It is a figure which shows the power converter device of an indirect water cooling system. It is a figure which shows the fin arrangement | positioning in the conventional power converter device. It is a disassembled perspective view of a power converter device. It is an external view of a power converter device. It is a figure which shows the refrigerant path of a power converter device. It is an external view of a power module. It is a typical block diagram of a hybrid type electric vehicle.

Explanation of symbols

1 Fin 2 Base 5 Semiconductor Element Group 13 IGBT Chip 14 Diode Chip 15 Insulating Substrate 17 Resin Case 200 Power Converter 216 Refrigerant Passage 500 Power Module

Claims (12)

A plurality of switching elements for converting a direct current supplied from the battery into a three-phase alternating current;
A drive control circuit for controlling operations of the plurality of switching elements;
A refrigerant passage for flowing a refrigerant from the upstream side to the downstream side in order to cool the switching element;
On one side, a base in which the plurality of switching elements are arranged in the direction from the upstream side to the downstream side of the refrigerant passage;
A plurality of fins provided on the base so as to be immersed in the refrigerant on a surface opposite to the one surface;
A capacitor for smoothing the DC voltage supplied from the battery,
The power conversion device, wherein the arrangement density of the plurality of fins is configured to increase from the upstream side to the downstream side of the refrigerant passage. The power conversion device according to claim 1,
The said fin is comprised with the cylindrical pin, The power converter device characterized by the above-mentioned. The power conversion device according to claim 2,
The power conversion device, wherein the arrangement density of the plurality of fins is configured to increase stepwise from the upstream side to the downstream side of the refrigerant passage. The power conversion device according to claim 3,
The power conversion device according to claim 1, wherein the number of fins is smaller on the upstream side than on the downstream side of the refrigerant passage. The power conversion device according to claim 1,
The plurality of fins are a plurality of straight fins extending in a direction in which the refrigerant flows. The power conversion device according to claim 5, wherein
An interval between adjacent straight fins among the plurality of straight fins is narrower on the downstream side than on the upstream side of the refrigerant passage. The power conversion device according to claim 6, wherein
The interval between the adjacent straight fins changes in stages,
The power converter according to claim 1, wherein the straight fin is divided at a portion that changes stepwise. The power conversion device according to claim 1,
The plurality of switching elements have the same calorific value on average. The power conversion device according to claim 1,
The plurality of fins are formed such that the downstream side of the refrigerant passage is higher than the upstream side. The power conversion device according to claim 1,
The power conversion device further includes a pump controlled to give a constant flow rate to the refrigerant passage. The power conversion device according to claim 1,
The plurality of switching elements are mounted on an insulating substrate disposed on the base. The power conversion device according to claim 11, wherein
The power conversion device, wherein the switching element is an IGBT.

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