JP2014082840A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for effectively cooling a reactor in a power conversion device having a stack unit and a reactor molded in resin.SOLUTION: A power conversion device 2 includes: a stack unit 20 comprising a plurality of flat semiconductor modules housing semiconductor elements and a plurality of flat cooling plates stacked alternately; a reactor 4 molded in resin; a case 10 housing the stack unit and the reactor; and a plate spring 3 for loading the stack unit in the stack direction. The reactor 4 includes a heat transfer plate 5 with part exposed to a surface of the resin mold and the other buried in the resin. The reactor 4 is fixed to the case 10. The stack unit 20 is arranged adjacently to the reactor 4. The plate spring 3 is in contact with both a cooling plate 21a at an end of the stack direction of the stack unit and the heat transfer plate 5 exposed to the resin mold surface of the reactor, between the stack unit 20 and the reactor 4.

Description

  The present invention relates to a power converter including an inverter circuit and a voltage converter circuit. In particular, the present invention relates to a power conversion device for driving a traveling motor of an electric vehicle. The “electric vehicle” in the present specification includes a hybrid vehicle and a fuel cell vehicle having both a motor and an engine.

  An electric vehicle includes an inverter circuit that converts DC power of a battery into AC power having a frequency suitable for driving a motor. Since the motor for driving an electric vehicle has a large output, the current handled by the power conversion device is large and the amount of heat generated is large. In particular, the amount of heat generated by a transistor (IGBT or MOSFET) used as a switching element or a diode connected in reverse parallel to the transistor is large. These semiconductor elements that handle large currents are sometimes called power elements. In order to effectively cool a power element, a structure in which a semiconductor element (power element) is housed in a flat plate type semiconductor module and a plurality of semiconductor modules and a plurality of flat plate type cooling plates are alternately stacked has been proposed (patent) Literatures 1-3). Such a laminate is referred to herein as a laminate unit.

  Some electric vehicles include a voltage converter circuit that boosts the voltage of the battery. Although the voltage converter circuit includes a reactor (passive element using a coil), the amount of heat generated by the reactor is also large. Therefore, a device has been devised for cooling to the reactor using the cooler of the laminated unit. In the laminated unit, a pipe for sending a refrigerant to the cooling plate and a pipe for discharging the refrigerant after cooling the semiconductor module are connected to the cooling plate at one end of the laminated unit. In patent document 1, a reactor is arrange | positioned so that the two pipes may be contact | connected. Moreover, in patent document 2, a reactor is arrange | positioned so that the cooling plate of a lamination | stacking unit edge part may contact | connect between two pipes. In the present specification, a power conversion apparatus includes a device including a laminated unit and a reactor, and includes a circuit that converts direct current to alternating current (inverter circuit) and / or a circuit that converts voltage (voltage converter circuit). Collectively.

JP2011-228426A JP 2011-200090 A JP 2011-167028 A

  The reactor may be molded with resin. If it does so, it will become difficult to diffuse the heat of a reactor outside. A conductive wire (typically a long metal plate bus bar) extends from the resin-molded reactor and is connected to other electrical components. In this case, the bus bar is the only heat transfer path. There is a risk of heating even other electrical components. On the other hand, in order to increase the cooling efficiency of the stacked unit, it is desirable to apply a load in the stacking direction with an elastic member so that the cooling plate and the semiconductor module are in close contact (for example, Patent Document 3). The present specification provides a technology for effectively cooling a reactor with a laminated unit by using an elastic member that loads the laminated unit in a laminating direction in a power conversion device having a laminated unit and a resin molded reactor. .

  One embodiment of the power conversion device disclosed in the present specification includes a heat transfer plate in which a part molded on the surface of the resin mold and the other part embedded in the resin is formed on a resin molded reactor. ing. The reactor is fixed to the case. The laminated unit is disposed adjacent to the reactor. And the elastic member is inserted between the laminated unit and the reactor in contact with both the cooling plate at the stacking direction end of the laminated unit and the heat transfer plate exposed on the resin mold surface of the reactor. The heat transfer plate and the elastic member may typically be metal plates. With the above configuration, the heat transfer plate and the elastic member serve as a heat transfer path, and the heat of the reactor in the resin is transferred to the cooling plate at the end of the laminated unit. The heat of the reactor can be effectively transferred to the laminated plate, and the amount of heat that moves through the bus bar that electrically connects the reactor and other components can be reduced.

  In one improvement of the power converter disclosed in this specification, the heat transfer plate is curved so as to approach the coil of the reactor inside the resin. By bringing the heat transfer plate closer to the reactor coil, the heat transfer efficiency of the reactor can be increased.

  Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a disassembled perspective view of the power converter device of an Example. It is a perspective view of a power converter. It is sectional drawing of the power converter device in XY plane of FIG. It is a block diagram of the electric power system of the electric vehicle containing a power converter device.

  A power converter 2 according to an embodiment will be described with reference to the drawings. FIG. 1 shows an exploded perspective view of the power conversion device 2, and FIG. 2 shows a perspective view of the power conversion device 2. FIG. 3 shows a cross-sectional view on the XY plane in the coordinate system of FIG. FIG. 2 shows a state where the cover is removed. The power conversion device 2 is a device that is mounted on an electric vehicle including two traveling motors, boosts the power of a battery, converts the power into an alternating current, and supplies the two motors.

  The power conversion device 2 includes a laminated unit 20, a reactor 4, and a capacitor unit 7 as main components. The power conversion device 2 includes a circuit board that controls a semiconductor element incorporated in the stacked unit as other main components, but illustration and description thereof are omitted. It should be noted that in the drawing, the depth of the case 10 is drawn low so that the layout of the components in the case can be easily understood. The description of the power system of the electric vehicle will be described later with reference to FIG.

  The stacking unit 20 is formed by alternately stacking a plurality of flat plate-type semiconductor modules 22 in which semiconductor elements are molded with resin and a plurality of flat plate-type cooling plates 21 through which a coolant passes. As shown in FIG. 3, the inside of the cooling plate 21 is a cavity, and through holes are provided at both ends in the longitudinal direction. The cooling plate 21 is made of a metal having a high thermal conductivity, for example, aluminum so that heat can be transmitted well. The through holes of adjacent cooling plates 21 are connected by a connecting pipe. Also, in the through hole of the cooling plate 21 at one end of the laminated body, a supply pipe 23 for supplying a refrigerant from the outside, and a discharge for discharging the refrigerant after passing through the cooling plate 21 and cooling the semiconductor module 22 to the outside. A tube 24 is attached. The through hole facing the other end of the laminate is closed. In the figure, it should be noted that reference numerals 21 and 22 are given only to one cooling plate and one semiconductor module, and reference numerals are omitted from the other cooling plates and semiconductor modules. However, only the cooling plate located at the end opposite to the end to which the supply pipe 23 and the discharge pipe 24 are connected is specially denoted by reference numeral 21a.

  The semiconductor element housed in the semiconductor module 22 is a transistor used as a switching element and a diode connected in antiparallel with the transistor. These semiconductor elements generate a large amount of heat because large power flows from the battery. Moreover, the power converter device 2 is provided with many semiconductor elements. Therefore, these semiconductor elements are concentrated in the stacked unit 20 and concentrated and cooled. In order to increase the heat transfer efficiency from the semiconductor module 22 to the cooling plate 21, the stacked unit 20 is accommodated in the case 10 while being loaded in the stacking direction. The case 10 is made of, for example, aluminum. In the cross-sectional view of FIG. 3, the illustration of the semiconductor element molded in the semiconductor module is omitted.

  The reactor 4 is a passive element in which a coil 14 is wound around a magnetic core 13 (see FIG. 3). The reactor main body 9 including the core 13 and the coil 14 is molded with the resin 8, and the main body cannot be seen from the outside. A metal heat transfer plate 5 is embedded in the resin mold 8, and a part thereof is exposed on the side surface of the resin mold 8. Although the function of the reactor 4 will be described later, it forms a part of a voltage converter provided in the power converter 2. Since a large current flows through the reactor 4, the reactor 4 also generates a large amount of heat. The reactor 4 is fixed to the fixing hole 12 on the lower surface of the case 10 by passing a bolt through a through hole 4 a provided in the lower part of the side surface.

  The laminated unit 20 is sandwiched and supported between the side wall 10 b of the case 10 and the reactor 4. The stacked unit 20 is sandwiched in the stacking direction. The side wall 10b that supports the laminated unit 20 is made thicker than the other side walls in order to ensure strength. The left and right slits 10a of the side wall 10b are provided to allow the refrigerant supply pipe 23 and the discharge pipe 24 to pass therethrough.

  Between the side wall 10 b and the reactor 4, the metal leaf spring 3 is sandwiched together with the laminated unit 20. The leaf spring 3 is fitted between the stacked unit 20 and the reactor 4 and applies a load in the stacking direction to the stacked unit 20. The reactor 4 receives the reaction force of the load. The leaf spring 3 is disposed so as to contact both the heat transfer plate 5 exposed on the side surface of the reactor 4 and the cooling plate 21 a at the end of the laminated unit 20. As well shown in FIG. 3, the heat transfer plate 5 approaches the reactor body 9 (coil 14) inside the resin mold 8 and the exposed portion 5 a exposed on the surface of the resin mold 8 of the reactor 4. It is comprised by the embedded curved part 5b which is curving.

  The cooling of the reactor body 9 by the heat transfer plate 5 and the leaf spring 3 will be described. The heat generated by the reactor body 9 is transmitted from the embedded curved portion 5b of the heat transfer plate 5 to the exposed portion 5a, and further transmitted to the leaf spring 3 that is in contact with the exposed portion 5a. Since the leaf spring 3 is also in contact with the cooling plate 21a at the end of the laminated unit 20, the heat transmitted to the leaf spring 3 is transferred to the cooling plate 21a. Eventually, the heat generated by the reactor body 9 is transferred to the cooling plate 21a (cooler associated with the laminated unit 20) via the heat transfer plate 5 and the leaf spring 3.

  Since the reactor body 9 is connected to the capacitor unit 7 by the bus bar 6, the heat generated by the reactor body 9 is also transmitted to the capacitor unit 7 via the bus bar 6. However, since the temperature of the cooling plate 21 a is lower than that of the capacitor unit 7, the amount of heat transferred to the cooling plate via the heat transfer plate 5 and the leaf spring 3 is greater than the amount of heat transferred via the bus bar 6. large. Therefore, the power converter 2 having the heat transfer plate 5 can reduce the amount of heat transferred to the capacitor unit 7 via the bus bar 6 as compared with the conventional device.

  With reference to the block diagram of FIG. 4, the electric power system of the electric vehicle 90 carrying the power converter device 2 is demonstrated. The electric vehicle 90 has two motors 61 and 62 for traveling. The power converter 2 boosts the output voltage of the battery 52, converts the DC power into AC power having a frequency suitable for traveling, and outputs the AC power to the motors 61 and 62. That is, the power conversion device 2 includes a voltage converter circuit 56 and two inverter circuits 57a and 57b. Further, current smoothing capacitors 53 and 54 are connected to the input side and the output side of the voltage converter circuit 56. The capacitors 53 and 54 are built in the capacitor unit 7 shown in FIGS. 1 to 3 in terms of hardware.

  The voltage converter circuit 56 includes a switching series circuit 51 g in which two switching circuits configured by anti-parallel connection of a transistor 58 and a diode 59 are connected in series, and the reactor 4. The transistor is typically an IGBT, but may be composed of other types of transistors such as MOSFETs. The voltage converter circuit 56 in FIG. 3 can boost the voltage from the left side (battery side) to the right side (inverter circuit side) in the drawing, and can increase the voltage from the right side to the left side in the drawing. Can step down. The voltage converter circuit 56 steps down the electric power generated by the motor using deceleration energy of the vehicle to a voltage suitable for the battery. The AC power generated by the motors 61 and 62 is input to the voltage converter circuit after the inverter circuits 57a and 57b convert it to DC. The configuration of the voltage converter circuit shown in FIG. 4 is well known and will not be described in detail.

  The first inverter circuit 57a has a configuration in which three switching series circuits 51a, 51b, 51c having the same configuration as the switching series circuit 51g of the voltage converter circuit 56 are connected in parallel. Similarly, the second inverter circuit 57b has a configuration in which three switching series circuits 51d, 51e, 51f are connected in parallel. AC is output from the midpoint of each switching series circuit. Since the configuration of the inverter circuit of FIG. 4 is well known, detailed description thereof is omitted.

  In other words, each switching series circuit shown in FIG. 4 has a configuration in which two transistors are connected in series and a diode is connected in antiparallel to each transistor. Each of the switching series circuits is housed in each of the plurality of semiconductor modules 22 shown in FIGS. That is, the stacked unit 20 shown in FIGS. 1 to 3 is a device in which switching series circuits 51a, 51b, 51c, 51d, 51e, 51f, and 51g are integrated. Moreover, as shown in FIG. 4, the reactor 4 is used as one component of a voltage converter circuit.

  The advantages and points to be noted of the technology shown in the embodiments will be described. In the power conversion device 2 of the embodiment, the laminated unit 20 is sandwiched and supported while being loaded by the leaf spring 3 between the reactor 4 whose main body is molded with resin and the case side wall 10b. A heat transfer plate 5 is embedded in the resin mold 8 of the reactor 4, and a part thereof is exposed on the side surface of the reactor 4 (resin mold 8). The leaf spring 3 that is inserted between the reactor 4 and the laminated unit 20 and loads the laminated unit 20 in the laminating direction is provided on both the cooling plate 21 a at the end of the laminated unit 20 and the exposed portion 5 a of the heat transfer plate 5. Touch. The resin embedding portion 5 b of the heat transfer plate 5 is curved so as to approach the reactor main body 9 (coil 14) inside the resin mold 8. The heat generated by the reactor body 9 is transferred to the cooling plate 21 a via the heat transfer plate 5 and the leaf spring 3. Therefore, the heat transmitted to the capacitor unit 7 via the bus bar 6 connecting the reactor body 9 and the capacitor unit 7 can be reduced.

  The leaf spring 3 corresponds to an example of an elastic member. The elastic member is not limited to a leaf spring, and may be a coil spring. The heat transfer plate 5 is curved so as to approach the reactor body 9 inside the resin mold 8, but the heat transfer plate 5 may be in contact with the coil 14 as long as the coil 14 is insulated.

  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: Power converter 3: Leaf spring 4: Reactor 5: Heat transfer plate 6: Bus bar 7: Capacitor unit 8: Resin mold 10: Case 10a: Slit 10b: Side wall 10c: Bottom surface 13: Core 14: Coil 20: Multilayer unit 21: Cooling plate 22: Semiconductor module 23: Supply pipe 24: Discharge pipe 51a-51f: Switching series circuit 52: Battery 53, 54: Capacitor 56: Voltage converter circuit 57a, 57b: Inverter circuit 58: Transistor 59: Diode 90: Electric car

Claims (2)

A multi-layer unit in which a plurality of flat-plate semiconductor modules containing semiconductor elements and a plurality of flat-plate cooling plates are alternately stacked;
A reactor molded with resin;
A case for accommodating the laminated unit and the reactor;
An elastic member that applies a load in the stacking direction to the stacking unit;
With
The reactor is equipped with a heat transfer plate that is partly exposed on the surface of the resin mold and the other part embedded in the resin.
A reactor is fixed to the case,
The laminated unit is placed adjacent to the reactor,
The elastic member is inserted between the stacked unit and the reactor in contact with both the cooling plate at the end in the stacking direction of the stacked unit and the heat transfer plate exposed on the resin surface of the reactor.
The power converter characterized by the above-mentioned.   The power conversion device according to claim 1, wherein the heat transfer plate is curved so as to approach the coil of the reactor inside the resin.

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