JP2012231616A - On-vehicle power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that heat radiation effect of an on-vehicle power conversion device using an insulation transformer decreases since the insulation transformer has a primary-side coil, a secondary-side coil, and a core insulated, respectively, and the problem that heat quantity of a hybrid automobile, an electric automobile, etc., increases since a large current flows from a high-voltage side to a low-voltage side.SOLUTION: A transformer has a core arranged on a heat sink in contact, and a module case is arranged at a periphery of a printed board, a connection terminal in a flat plate shape for electric connection and heat transfer from the primary-side coil or/and the secondary-side coil to the printed board is insert-molded to the module case, and the primary-side coil or/and the secondary-side coil are connected to the heat sink through the connection terminal and printed board. A switching circuit and a rectifier circuit are packaged with semiconductor sealing resin charged in the module case.

Description

The present invention relates to a heat dissipation structure for an in-vehicle power conversion device used for a hybrid vehicle, an electric vehicle, or the like.

Conventionally, high-voltage batteries that drive motors for driving are installed in hybrid vehicles and electric vehicles, but on-board electrical components such as electric power steering and electric mirrors are used using the high voltage of high-voltage batteries. When doing so, it is necessary to convert the power to the rated voltage of these in-vehicle electrical components.

However, it is known to use a power converter provided with a separate transformer in which a secondary coil is insulated from a primary coil in order to prevent an electric shock accident when converting high voltage into power. Since such an insulating transformer insulates the primary side coil, the secondary side coil, and the core, respectively, the heat dissipation effect is reduced. In the case of a hybrid vehicle, an electric vehicle, or the like, a large amount of current flows on the low voltage side with respect to the high voltage side, so that the amount of heat generation increases. In order to improve the heat dissipation effect of the insulation transformer, the surface areas of the primary side coil, the secondary side coil, and the core may be increased. However, the surface areas of the primary side coil, the secondary side coil, and the core are increased. And there was a problem that the transformer was enlarged. In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2004-335780 (hereinafter referred to as “Patent Document 1”) is known.

FIG. 6 shows a cross-sectional view (A) of the transformer described in Patent Document 1 and a side view (A) of the transformer. In FIG. 6, in the resonance type switching power supply, the power on the input side is transmitted to the output side, and the leakage inductance is used as an L component of the resonance circuit. Here, the transformer 120 includes a first winding 121 and second windings 122a and 122b having a cross-sectional area larger than that of the first winding 121. The first winding 121 is housed in the inner region so as to be close to the first outer surface 125 of the transformer 121, and the second windings 122a and 122b are arranged in the first winding. It is accommodated in an inner region of the second outer surface 126 facing the first outer surface 125 of the transformer 120 so as to be magnetically coupled to the wire 121. The transformer 120 is attached so that the first outer surface 125 contacts the heat sink 140.

Further, the ends of the second windings 122a and 122b drawn out from the transformer 120 are thermally connected to the heat sink 140 through an insulating member 141 having high thermal conductivity to radiate heat from the transformer. What has been proposed.

However, since the above-mentioned Patent Document 1 has a configuration in which the end of the second winding is electrically connected and a configuration in which it is thermally connected, an extra space is generated on the heat sink, Although the transformer can be reduced in size, it is difficult to reduce the size of the entire power conversion device. In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2007-221919 (hereinafter “Patent Document 2”) is known.

In Patent Document 2, a transformer having a primary side coil and a secondary side coil, and a rectifying element that rectifies an induced voltage of the secondary side coil, the secondary side coil having a plurality of A coil conductor portion, and an end portion of each coil conductor portion is soldered to a conductor pattern formed on a metal substrate via an insulating layer, and the primary coil is interposed between the plurality of coil conductor portions. Has been inserted.

There has been proposed a DC / DC converter including the AC / DC conversion module substrate and a switching circuit connected to the primary coil, and directly mounting the AC / DC conversion module substrate on a heat dissipation base plate.

JP 2004-335780 A JP 2007-221919 A

However, the conventional power conversion device has the following problems. That is, in Patent Document 2, since the secondary coil of the transformer is fixed to the conductor pattern on the metal substrate by soldering, and the secondary coil and the rectifying unit are also connected by soldering, It is possible to reduce the size, reduce the number of parts, and reduce the number of assembly steps. Further, when the metal substrate is directly mounted on the heat radiating base plate, the secondary side coil through which a large current flows can be installed on the heat radiating base plate with a small thermal resistance, and the heat radiation effect is large, and the secondary side coil Although the size can be reduced, it is necessary to provide the connection surface of the secondary coil and the mounting surface of the rectifying element on the metal substrate by providing the rectifier circuit in the secondary coil, and the area of the metal substrate increases. Therefore, it is difficult to reduce the size of the entire DC / DC converter.

The present invention has been made in view of the above problems, and aims to provide an on-vehicle power conversion device capable of reducing the size of the transformer and the power conversion device and simplifying the assembly configuration, and having an excellent heat dissipation effect. .

In order to solve the above problems, the present invention is configured as follows. That is, in the first aspect of the present invention, a transformer for transformation composed of a primary side coil, a secondary side coil, and a core is provided, and the primary side coil and the secondary side coil are formed of a flat bus bar. The transformer is an insulating transformer whose output side is insulated from the input side, and includes a printed circuit board on which an electronic circuit composed of a semiconductor element is arranged, and the on-vehicle power conversion device including the printed circuit board on a heat sink The transformer is arranged so that the core is in contact with the heat sink, and is a flat connection terminal that performs electrical connection and heat transfer from the primary coil or / and the secondary coil to the printed circuit board. The connection terminal is insert-molded in the case, and the primary coil and / or the secondary coil are connected to the connection terminal and the connection coil. The vehicle power conversion device, characterized in that connected to the heat sink through the printed circuit board.

In the above configuration, the case may be a module case disposed around the printed circuit board, and the electronic circuit disposed on the printed circuit board may be packaged with a semiconductor sealing resin filled in the module case. Good. The case may be formed of an insulating resin, and the connection terminal 62 may be covered with an insulating layer at a contact portion with the case.

As another invention, a transformer for transformation composed of a primary side coil, a secondary side coil and a core is provided, and the primary side coil and the secondary side coil are formed of flat bus bars. The transformer is an insulating transformer having an output side insulated from an input side, and includes a printed circuit board on which a switching circuit and a rectifier circuit are arranged. The in-vehicle DC / DC converter includes the printed circuit board on a heat sink. Is arranged such that the core is in contact with the heat sink, a module case is arranged around the printed circuit board, and the switching circuit and the rectifier circuit are packaged by a semiconductor sealing resin filled in the module case, The print from the primary side coil or / and the secondary side coil to the module case A flat connection terminal for electrical connection to the substrate and heat transfer is insert-molded, and the primary side coil or / and the secondary side coil are connected to the heat sink via the connection terminal and the printed circuit board. DC / DC converter for in-vehicle use.

As described above, the transformer is arranged so that the core is in contact with the heat sink, the module case is arranged around the printed circuit board, and the electrical connection from the primary coil and / or the secondary coil to the printed circuit board is arranged on the module case. A flat connection terminal for heat transfer is insert-molded, and the primary side coil or / and the secondary side coil are connected to a heat sink via the connection terminal and the printed circuit board to enhance the heat dissipation effect of the transformer, and the transformer Can be downsized and the assembly configuration can be simplified.

Further, since the switching circuit and the rectifier circuit are packaged by the semiconductor sealing resin filled in the module case, the printed circuit board can be reduced in size from a configuration in which a plurality of semiconductor elements are individually packaged. Furthermore, since it is not necessary to provide a space for providing the connection terminals by insert-molding the connection terminals into the module case, the power converter can be downsized.

1 is a circuit diagram of an in-vehicle DC / DC converter according to a first embodiment of the present invention. 1 is a perspective view of an in-vehicle DC / DC converter according to a first embodiment. 1 is a perspective view illustrating a configuration of a transformer according to a first embodiment. It is the figure which looked at the AA cross section which showed before the assembly of the vehicle-mounted DC / DC converter of FIG. 1 from the arrow direction. It is the figure which looked at the AA cross section of the vehicle-mounted DC / DC converter of FIG. 1 from the arrow direction. (A) is sectional drawing of the transformer made into patent document 1, (A) is a side view of a transformer.

Hereinafter, examples showing embodiments of the present invention will be described with reference to FIGS. Here, a step-down DC / DC converter for vehicle use is taken up as an example of an in-vehicle power converter.

1 is a circuit diagram of a DC / DC converter according to a first embodiment of the present invention, FIG. 2 is a perspective view of the DC / DC converter, and FIG. 2 is a perspective view showing a configuration of a transformer according to the first embodiment. 3 is a cross-sectional view taken along the line A-A showing the DC / DC converter for in-vehicle use shown in FIG. 1 as viewed from the direction of the arrow, and FIG. The figure seen from the direction is shown in FIG.

1 to 3, a hybrid vehicle or an electric vehicle is provided with a high-voltage battery 38 having a maximum voltage of 600 V that is used to drive a motor for traveling, and a vehicle such as a power window or an electric mirror is mounted from the battery 38. When power is supplied to an electrical component, the in-vehicle DC / DC converter 80 is used to step down the rated voltage of the in-vehicle electrical component. The in-vehicle DC / DC converter 80 includes a switching circuit 70 disposed on a printed circuit board 40 a, and a transformer composed of a primary side coil 12, a secondary side coil 14, and a core 16 at the subsequent stage of the switching circuit 70. 10, a rectifier circuit 72 disposed on the printed circuit board 40 b is provided at the subsequent stage of the transformer 10, a smoothing circuit 74 is provided at the subsequent stage of the rectifier circuit 72, and the switching to the in-vehicle DC / DC converter 80 is performed. A control unit 76 that performs feedback control to the circuit 70 is provided.

The switching circuit 72 includes a field effect transistor 30a, 30b, 30c, 30d (hereinafter referred to as “FET”) connected in a full bridge shape, an FET 30e to the FET 30a, an FET 30f to the FET 30b, an FET 30g to the FET 30c, and an FET 30g to the FET 30d. Each FET30h is connected in parallel. Further, the rectifier circuit 72 is configured by connecting the cathode side of the diode 32a to one end of the secondary side coil 14, and connecting the cathode side of the diode 32b to the other end of the secondary side coil 14. 32b are Schottky barrier diodes.

Further, the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h and the diodes 32a, 32b are semiconductor elements that are not packaged. Further, the smoothing circuit 74 includes a choke coil 34 and a capacitor 36.

The printed circuit boards 40a and 40b and the transformer 10 and the smoothing circuit 74 are disposed on a metal heat sink 20, and the printed circuit boards 40a and 40b and the transformer 10 and the smoothing circuit 74 are disposed on the heat sink 20. Fins 22 for heat dissipation are formed on the opposite surface.

The primary coil 12 is formed by winding a flat bus bar whose surface is covered with an enamel layer for four turns, and the secondary coil 14 is a secondary bus formed by forming a flat bus bar into a ring shape. The side coil 14a and the secondary side coil 14b are combined and wound around for one turn. Further, the secondary coils 14a and 14b are electrically connected by connecting the connection ends 15a and 15c with screws 66, and the primary coil 12 is sandwiched between the secondary coils 14a and 14b. Are arranged to be.

The core 16 is composed of two cores 16a and 16b obtained by molding ferrite into an E shape, and the cores 16a and 16b form protrusions 17a and 17b. Further, the primary side coil 12 and the secondary side coils 14a, 14b are disposed between the cores 16a, 16b, and the protrusions 17a, 17b are connected to the primary side coil 12, the secondary side coils 14a, The primary coil 12 and the secondary coils 14a and 14b are magnetically connected to each other so as to penetrate through 14b.

In addition, insulating cases 18a, 18b, 18c, and 18d formed of epoxy are provided between the primary side coil 12, the secondary side coils 14a and 14b, and the cores 16a and 16b. Further, when the insulating cases 18a, 18b, 18c, 18d have a structure in which the primary side coil 12 and the secondary side coils 14a, 14b are fully molded, the primary side coil 12 and the secondary side coils 14a, 14b Since the probability of occurrence of cracks increases due to the difference in thermal expansion coefficient between the cores 16a and 16b, the insulating cases 18a, 18b, 18c and 18d are connected to the primary coil 12 and the secondary coils 14a and 14b, The structure is not in close contact with the cores 16a and 16b.

Further, a module case 60a surrounding the printed board 40a and a module case 60b surrounding the printed board 40b are provided on the heat sink 20, and the module cases 60a and 60b are formed of an insulating resin. Further, the primary coil 12 and the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, and 30h are electrically connected, and the secondary coils 14a and 14b and the diodes 32a and 32b are electrically connected. The connection terminals 62a, 62b, 62c, 62d formed into a flat plate shape with copper are insert-molded in the module cases 60a, 60b.

Further, the end portion 64a of the connection terminal 62a is fixed and electrically connected to the connection portion 13a of the primary side coil 12 with a screw 66, and the end portion 64a of the connection terminal 62b is connected to the primary side coil 12. The connection portion 13b and the screw 66 are fixed and electrically connected. Further, the end portion 64a of the connection terminal 62c is fixed and electrically connected to the connection end portion 15b of the secondary coil 14a with a screw 66, and the end portion 64a of the connection terminal 62d is connected to the secondary coil 14b. The connection end 15d and the screw 66 are electrically connected.

Further, the operation of the in-vehicle DC / DC converter 80 supplies a pulse signal for alternately turning on / off the FETs 30a, 30d, 30e, 30h and the FETs 30b, 30c, 30f, 30g from the control unit 76, and The direct current from the battery 38 is converted into a harmonic alternating current, sent to the primary coil 12, and transformed by the transformer 10. Further, the outputs from the secondary coils 14a and 14b are rectified to direct current by the rectifier circuit 72, and are smoothed and output as a low-voltage direct current voltage by the smoothing circuit 74.

Next, the laminated structure of the printed circuit board will be described with reference to FIGS.

4 and 5, the printed circuit boards 40a and 40b include an alumina layer 44 formed of aluminum oxide, a copper pattern 42 in which a wiring pattern is laminated on the surface of the alumina layer 44, and the copper pattern 42. From the solder layer 46 for electrically connecting the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, and the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h on the solder layer 46 It is configured. The wiring pattern includes a connection terminal copper pattern 43 for electrical connection with the end portions 64b of the connection terminals 62a, 62b, 62c, 62d. Further, a conductive adhesive resin 48 using copper powder as a conductive filler is applied to the connection surface between the printed boards 40a and 40b and the heat sink 20. Further, wiring on the printed circuit boards 40a and 40b of the switching circuit 70 and the rectifier circuit 72 is performed by the copper pattern 42 and wire bonding.

Further, the length from the end 64b of the connection terminals 62a, 62b, 62c, 62d to the heat sink 20 is ΔTa, and is connected to the connection terminals 62a, 62b, 62c, 62d of the printed circuit boards 40a, 40b. When the length from the connection terminal copper pattern 43 to the conductive adhesive resin 48 is ΔTb, if ΔTa ≦ ΔTb, the end portions 64b of the connection terminals 62, a, 62b, 62c, 62d and the printed circuit board 40a , 40b can be connected securely. Further, after installing the printed circuit boards 40a, 40b and the module cases 60a, 60b on the heat sink 20, the semiconductor sealing resin 50 is filled up to the upper surfaces of the module cases 60a, 60b, and the FET 30a on the printed circuit boards 40a, 40b , 30b, 30c, 30d, 30e, 30f, 30g, 30h and the diodes 32a, 32b are packaged.

With the above configuration, even if heat is generated in the primary side coil 12 and the secondary side coils 14a and 14b, the primary side coil 12 and the secondary side coils 14a and 14b are connected to the connection terminals 62a, 62b and 62c. , 62d are used as heat dissipation paths to dissipate heat to the heat sink 20 via the printed circuit boards 40a, 40b. Further, since the heat resistance between the printed boards 40a, 40b and the heat sink 20 is reduced by connecting the printed boards 40a, 40b and the heat sink 20 with the conductive adhesive resin 48, the primary coil 12 and the secondary side coils 14a, 14b can be efficiently transferred to the heat sink 20. Similarly, in the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, and 30h and the diodes 32a and 32b, which are said to generate a large amount of heat, the heat sink 20 is efficiently heated by the conductive adhesive resin 48. Can be transmitted. Furthermore, the conductive adhesive resin 48 has a copper powder particle size of 30 μm, and the thickness of the conductive adhesive resin 48 is 30 μm when the conductive adhesive resin 48 is applied most thinly, so that the thermal resistance can be further reduced.

Further, the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, and 30h are packaged in the module case 60a and the diodes 32a and 32b are packaged by the semiconductor sealing resin 50 filled in the module case 60b. Thus, the printed circuit boards 40a and 40b can be downsized from the configuration in which the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, and 30h and the diodes 32a and 32b are individually packaged with resin or metal. it can.

As a modification of the first embodiment, the in-vehicle DC / DC converter 80 of the step-down type is taken up as an example of the in-vehicle power converter, but the present invention is not limited to this configuration, You may implement in the power converter device. The connection terminals 62a, 62b, 62c, 62d may be formed of a metal other than copper, and the connection terminals 62a, 62b, 62c, 62d are at least partially embedded in the module cases 60a, 60b. Contact between the connection portions 13a and 13b of the primary side coil 12, the connection end portions 15b and 15d of the secondary side coils 14a and 14b, and the connection terminal copper pattern 43 of the printed circuit boards 40a and 40b is a surface. As long as it is a contact, you may make it into arbitrary shapes according to design circumstances. Further, the connection terminals 62a, 62b, 62c and 62d are covered with an insulating layer such as an enamel layer, and at least the connection portions 13a and 13b of the primary coil 12 and the connection end portions of the secondary coils 14a and 14b. If only the connection surfaces with 15b and 15d are exposed, the material of the module cases 60a and 60b may be formed of other than insulating resin.

In this embodiment, the switching circuit 70 and the rectifier circuit 72 are arranged on the individual printed boards 40a and 40b, respectively. However, the switching circuit 70 and the rectifier circuit 72 are arranged on a single printed board. Also good. Further, the connection terminals 62a, 62b, 62c and 62d may be provided only in either the primary coil 12 or the secondary coils 14a and 14b.

The circuit configurations of the switching circuit 70, the rectifier circuit 72, and the smoothing circuit 74 may be arbitrarily changed according to design circumstances, and the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, and 30h Switching elements other than effect transistors may be used, and diodes other than Schottky barrier diodes may be used as the diodes 32a and 32b. Further, the FETs 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h and the diodes 32a, 32b may be packaged semiconductor elements.

The connection terminals 62a, 62b, 62c, 62d, the connection portions 13a, 13b of the primary coil 12, and the connection ends 15b, 15d of the secondary coils 14a, 14b are fixed by the screws 66. For example, soldering or conductive adhesive may be used in addition to the stopper.

10: Transformer
12: Primary coil
13a, 13b: Connection part
14, 14a, 14b: Secondary coil
15a, 15b, 15c, 15d: Connection end
16, 16a, 16b: Core
17a, 17b: Projection
18, 18a, 18b, 18c, 18d: Insulation case
20: Heat sink
22: Fin
30, 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h: Field Effect Transistor (FET)
32, 32a, 32b: Diode
34: Choke coil
36: Capacitor
38: Battery
40a, 40b: Printed circuit board
42: Copper pattern
43: Copper pattern for connection terminals
44: Alumina layer
46: Solder layer
48: Conductive adhesive resin
50: Semiconductor sealing resin
60a, 60b: Module case
62a, 62b, 62c, 62d: Connection terminal
64a, 64b: End
66: Screw
70: Switching circuit
72: Rectifier circuit
74: Smoothing circuit
76: Control unit
80: Automotive DC / DC converter

Claims (5)

A transformer for transformation composed of a primary coil, a secondary coil, and a core;
The primary side coil and the secondary side coil are formed of flat bus bars,
The transformer is an insulating transformer whose output side is insulated from the input side,
Provided with a printed circuit board on which electronic circuits composed of semiconductor elements are arranged,
In the in-vehicle power converter equipped with the printed circuit board on a heat sink,
The transformer places the core in contact with the heat sink,
A case having a flat connection terminal for electrical connection and heat transfer from the primary side coil or / and the secondary side coil to the printed circuit board,
The connection terminal is insert-molded in the case,
The on-vehicle power conversion device, wherein the primary coil or / and the secondary coil are connected to the heat sink via the connection terminal and the printed board. The case is a module case arranged around the printed circuit board,
The in-vehicle power converter according to claim 1, wherein the electronic circuit disposed on the printed board is packaged by a semiconductor sealing resin filled in the module case. The in-vehicle power converter according to claim 1 or 2, wherein the case is formed of an insulating resin. The in-vehicle power converter according to claim 1, wherein the connection terminal is covered with an insulating layer at a contact portion with the case. A transformer for transformation composed of a primary coil, a secondary coil, and a core;
The primary side coil and the secondary side coil are formed of flat bus bars,
The transformer is an insulating transformer whose output side is insulated from the input side,
A printed circuit board on which a switching circuit and a rectifier circuit are arranged is provided.
In the automotive DC / DC converter provided with the printed circuit board on a heat sink,
The transformer places the core in contact with the heat sink,
Placing a module case around the printed circuit board;
The switching circuit and the rectifier circuit are packaged by a semiconductor sealing resin filled in the module case,
The module case is insert-molded with a flat connection terminal for electrical connection and heat transfer from the primary coil or / and the secondary coil to the printed circuit board,
The in-vehicle DC / DC converter, wherein the primary coil or / and the secondary coil are connected to the heat sink via the connection terminal and the printed circuit board.

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