JP2013188010A - Insulation type switching power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a very efficient and small insulation type switching power supply device where a switching element for secondary side synchronous rectification of the insulation type switching power supply device is mounted on a printed board.SOLUTION: A lead terminal of a MOSFET 114 is inserted into a through hole of a printed board 201 and is soldered to a land 300 on a component mounting surface of the printed board 201. Further, a lead terminal formed at a first conductor 204a included in an insert member 200 is inserted into a through hole of the printed board 201 and is soldered to a land 301 on the component mounting surface of the printed board 201. The land 300 and the land 301 are located close to each other, and a solder resist is not applied to a pattern connecting the land 300 with the land 301. The first conductor 204a is connected with a secondary side coil 110 of a transformer 107 by a screw 207 at a terminal board member 205.

Description

  The present invention relates to an insulating switching power supply device having a transformer.

  As an in-vehicle insulated switching power supply device mounted on an electric vehicle or a hybrid car, for example, an insulated DC / DC converter device for converting a DC voltage level is known. This insulation type DC / DC converter device performs an operation to step down a high voltage supplied from a driving battery represented by a lithium ion battery to a low voltage that is a power supply voltage of auxiliary equipment components while maintaining insulation. .

  In such an insulation type DC / DC converter device, a synchronous rectification method using a switching element typified by a MOSFET as the secondary side rectifying element is generally widely used, and the MOSFET is mounted on a metal substrate. Many insulated DC / DC converter devices having a structure with improved heat dissipation have been developed (for example, see Patent Document 1).

JP 2011-50160 A

  As disclosed in Patent Document 1, by making the rectification method a synchronous rectification method, the efficiency in a high load region can be generally improved as compared with the case where a diode is used for the rectification element. Further, by mounting the MOSFET on the metal substrate, the heat generation of the MOSFET caused by the large current flowing on the secondary side can be efficiently radiated to some extent.

  However, when the MOSFET is mounted on a metal substrate, an extra connector and harness for inputting the control signal of the MOSFET are required, which increases the cost and reduces the vibration resistance. In addition, since heat is radiated through the metal substrate, heat radiation is inferior to a structure in which the heat is released by being brought into close contact with the housing via an insulating heat radiating sheet or the like, and there is a problem that the performance of the MOSFET cannot be fully exhibited.

  On the other hand, when a MOSFET is mounted on a printed circuit board, the control signal of the MOSFET can be easily wired using a pattern on the printed circuit board, which does not cause an increase in cost and a decrease in vibration resistance. In addition, by mounting a MOSFET of a lead type package, it is possible to have a structure in which it is cooled by being in close contact with the housing via the insulating heat-dissipating sheet or the like, and heat dissipation can be improved.

  However, when a MOSFET is mounted on a printed circuit board, it is necessary to pass a large secondary current through the pattern on the printed circuit board, which may cause deterioration of the circuit board or burnout due to self-heating of the pattern.

  The present invention has been made to solve the above-described problems. Even when the secondary-side synchronous rectification switching element of the isolated switching power supply device is mounted on a printed board, the heat generated by a large current flowing through the printed board. It is an object of the present invention to provide a highly efficient and small insulated switching power supply device that realizes a configuration in which the above problem does not easily occur.

In order to solve such a problem, an insulated switching power supply device according to the present invention includes a transformer having a high-voltage side primary winding and a low-voltage side secondary winding, and an operation for converting alternating current generated by the transformer into direct current. A switching element having a control terminal, a first output terminal, and a second output terminal, and a control circuit that generates a control signal for controlling the switching element and inputs the control signal to the control terminal. An insulated switching power supply device comprising: a mounted printed circuit board; the transformer; the switching element; and a housing for fixing the printed circuit board.
A first conductor that electrically connects the first output terminal of the switching element and the low-voltage secondary winding, and a second output terminal of the switching element and the housing are electrically connected. And a connection between the switching element and the first conductor and a connection between the switching element and the second conductor are connected via a pattern on the printed circuit board. It is characterized by.

  According to the insulated switching power supply device according to the present invention, the printed circuit board is protected from heat generation by flowing a large current flowing through the switching element on the secondary side to the first conductor and the second conductor different from the printed circuit board. In addition, the first conductor and the second conductor are configured to overlap each other, thereby making it possible to bring the connection portion between the switching element and the first and second conductors to the maximum extent and preventing the heat generation of the printed circuit board. Thus, the reliability of the substrate can be improved.

It is a main circuit block diagram of the insulation type switching power supply device concerning Embodiment 1 of this invention. It is a top view which shows the connection part of the trans | transformer and rectifier which comprise the insulation type switching power supply which concerns on Embodiment 1 of this invention. It is sectional drawing which shows a part of connection part of the trans | transformer and rectifier which comprise the insulation type switching power supply which concerns on Embodiment 1 of this invention. It is sectional drawing which shows a part of connection part of the trans | transformer and rectifier which comprise the insulation type switching power supply which concerns on Embodiment 1 of this invention. It is sectional drawing which shows a part of connection part of the trans | transformer and rectifier which comprise the insulation type switching power supply which concerns on Embodiment 1 of this invention. It is a top view which shows the connection of the center tap part of the trans | transformer which comprises the insulation type switching power supply device concerning Embodiment 2 of this invention. It is sectional drawing which shows the connection part of the trans | transformer and rectifier which comprise the insulation type switching power supply device concerning Embodiment 3 of this invention. It is sectional drawing which shows a part of connection part of the trans | transformer and rectifier which comprise the insulation type switching power supply which concerns on Embodiment 3 of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an insulated switching power supply device according to the invention will be described with reference to the drawings. In the following description, an insulated DC / DC converter device will be described as an example of the insulated switching power supply device.

Embodiment 1 FIG.
1 is a circuit diagram showing a main circuit configuration of an insulation type DC / DC converter device according to Embodiment 1 of the present invention. This DC / DC converter device receives, for example, a high voltage from about 100 V to about 600 V supplied from an on-vehicle high voltage battery (not shown) on input terminals A and B, and on-vehicle accessory system parts from output terminals C and D. The power supply voltage of 12V to 16V is output.

  Details of the operation of the DC / DC converter device will be described. A high DC voltage supplied from the input terminals A and B is input to the full bridge circuit 100. The full bridge circuit 100 includes switching elements 101, 102, 103, and 104 represented by MOSFETs, and performs an operation of generating an AC voltage from a DC voltage by these switching elements 101, 102, 103, and 104. The AC component generated by this operation is mainly absorbed by the input capacitor 105 and does not generate a large noise in the input line.

  The AC voltage generated by the full bridge circuit 100 is applied to the primary coil 108 of the resonance coil 106 and the transformer 107 connected in series. The resonance coil 106 causes a resonance operation with capacitances (not shown) connected in parallel with the switching elements 101, 102, 103, and 104, and suppresses switching loss of the switching elements 101, 102, 103, and 104.

  When an AC voltage is applied to the primary side winding 108 of the transformer 107, an AC voltage corresponding to the turns ratio of the transformer 107 is generated in the secondary side windings 109 and 110 of the transformer 107. The AC voltage generated here is input to the secondary side rectifier circuit 111, and the switching elements 112, 113, 114, and 115 represented by MOSFET are operated in synchronization with the AC voltage. By the operation of the MOSFETs 112, 113, 114, and 115, a DC voltage including an AC component is generated at the center tap that is a connection point of the secondary windings 109 and 110. By smoothing this AC component using a smoothing circuit 118 composed of a smoothing coil 116 and an output capacitor 117, a desired flat output voltage is generated at the output terminals C and D. The minus terminal D on the output side is not clearly provided, and a housing (not shown) plays a role together with the GND connection points G1, G2, and G3.

  FIG. 2 is a top view showing a structure of a connection portion between the transformer 107 and the secondary side rectifier circuit 111 constituting the DC / DC converter device shown in FIG. In order to show the structure more accurately, some members or parts of the members are not shown.

  In FIG. 2, the primary winding 108 of the transformer 107 does not show connection terminals and connection destination members. A configuration in which the conductor member responsible for electrical connection of the primary winding 108 is integrally formed with the insert molding member 200 may be employed. The secondary winding 109 of the transformer 107 is positioned on the lower side in the drawing of the printed circuit board 201, and the secondary winding 110 is positioned on the upper side in the drawing of the printed circuit board 201. As shown in FIG. 2, the performance of the transformer 107 can be improved by adopting a structure in which the primary side winding 108 is sandwiched between the secondary side windings 109 and 110.

  Reference numeral 202 denotes a magnetic core that forms a magnetic path of the transformer 107. In this embodiment, the E-core 202a and the I-type core 202b shown in FIG. It is pressed against and fixed to the housing 203 by a spring member (not shown).

  The MOSFETs 112, 113, 114, and 115 that constitute the secondary side rectifier circuit 111 have the drain terminals corresponding to the first output terminals at the secondary side windings 110 and 109 of the transformer 107 via the first conductors 204a and 204b. Is electrically connected. Further, it is pressed against the housing 203 by an unillustrated spring member via an insulating heat radiating sheet (not shown), is mechanically fixed, and is thermally coupled to the housing 203.

  Further, the MOSFETs 112, 113, 114, and 115, the E-type core 202 a and the I-type core 202 b of the transformer 107, the printed circuit board 201, the terminal block member 205, and the second conductor 206 are mechanically fixed to the housing 203. Yes.

  The printed circuit board 201 is fixed to the housing 203 by a screwing member (not shown), a pattern for a control signal input to the control terminals of the MOSFETs 112, 113, 114, and 115, and the MOSFETs 112, 113, 114, and 115 A pattern for connecting the drain terminal and the source terminal to the first conductors 204a and 204b and the second conductor 206 is formed. Further, an opening 201 a is provided at a location overlapping the terminal block member 205 of the printed circuit board 201.

  The insert molding member 200 is a member in which the first conductors 204a and 204b and the second conductor 206 are integrally molded with resin. In FIG. 2, in order to show the structures of the first conductors 204 a and 204 b and the second conductor 206, portions above the respective conductors are not shown.

  The first conductor 204 a electrically connects the drain terminals of the MOSFETs 114 and 115 and the secondary winding 110 of the transformer 107 by screwing with screws 207. The first conductor 204 b electrically connects the drain terminals of the MOSFETs 112 and 113 and the secondary winding 109 of the transformer 107 by screwing with screws 208. The second conductor 206 electrically connects the source terminals of the MOSFETs 112, 113, 114, and 115 and the housing 203 by screwing with screws 209. In addition, since the printed circuit board 201 and the second conductor 206 are fixed to the threaded portion by a screw 211 because they are provided on a post (not shown) of the housing 203. Note that the first conductors 204a and 204b and the second conductor 206 have overlapping regions.

  The terminal block member 205 is disposed at an intermediate portion between the transformer 107 and the MOSFETs 112, 113, 114, and 115 and has three female screw portions, one of which has a higher shape than the other two locations. Yes. In addition to the connection by the screws 207 and 208, the secondary windings 109 and 110 of the transformer 107 are electrically connected by screw tightening with the screw 210. These electrical connections are also responsible for mechanical connections.

3 to 5 are cross-sectional views showing in more detail the structure of the connecting portion between the transformer 107 and the secondary side rectifying element 111 shown in FIG.
As shown in FIG. 3, the lead terminal of the MOSFET 114 constituting the secondary side rectifier circuit 111 is inserted into a through hole of the printed board 201 and connected by soldering at a land 300 on the component mounting surface of the printed board 201. In addition, the lead terminal formed on the first conductor 204 a included in the insert member 200 is also inserted into the through hole of the printed board 201 and soldered and connected to the land 301 on the component mounting surface of the printed board 201. It is desirable that the land 300 and the land 301 be positioned as close as possible to each other, and it is desirable that no solder resist be applied to the pattern connecting the land 300 and the land 301. The first conductor 204a is connected to the terminal block member 205 by screwing using the secondary winding 110 of the transformer 107 and the screw 207.

  As shown in FIG. 4, the lead terminal of the MOSFET 112 constituting the secondary side rectifier circuit 111 is inserted into the through hole of the printed board 201 and soldered and connected to the land 400 on the component mounting surface of the printed board 201. . The lead terminal formed on the first conductor 204b included in the insert member 200 is also inserted into the through hole of the printed board 201 and soldered and connected to the land 401 on the component mounting surface of the printed board 201. It is desirable that the land 400 and the land 401 be positioned as close as possible to each other, and it is desirable that no solder resist be applied to the pattern connecting the land 400 and the land 401. The first conductor 204b is connected to the terminal block member 205 by screwing using the secondary winding 109 of the transformer 107 and the screw 208.

  Further, as shown in FIG. 5, the lead terminal of the MOSFET 113 constituting the secondary side rectifier circuit 111 is inserted into the through hole of the printed board 201 and soldered and connected to the land 500 on the component mounting surface of the printed board 201. . In addition, the lead terminal formed on the second conductor 206 provided in the insert member 200 is also inserted into the through hole of the printed board 201 and soldered and connected to the land 501 on the component mounting surface of the printed board 201. It is desirable that the land 500 and the land 501 be positioned as close as possible to each other, and it is desirable that no solder resist be applied to the pattern connecting the land 500 and the land 501. Note that the second conductor 206 is connected to the housing 203 and a screw 209 by screw tightening. Although this location is convex in FIG. 5, it is not limited to this.

  Although not shown in the figure, the inverter 107 further includes an inverter circuit that applies an alternating current to the primary winding 108 of the transformer 107, and has a third conductor that electrically connects the primary winding 108 and the inverter circuit. The third conductor may be further integrated with the integrated member of the first conductor and the second conductor.

  As described above, according to the first embodiment, the large current flowing through the MOSFETs 112, 113, 114, and 115, which are the switching elements on the secondary side of the transformer 107 constituting the isolated switching power supply device, is separated from the printed circuit board 201. The printed circuit board 201 is protected from heat generation by flowing through the first conductors 204a and 204b and the second conductor 206, and the first conductors 204a and 204b and the second conductor 206 are overlapped to constitute the MOSFET 112. , 113, 114, 115 and the first and second conductors 204a, 204b, 206 can be connected as close as possible, heat generation of the printed circuit board 201 can be prevented, and the reliability of the board can be improved. Can be connected.

  Further, integrating the first conductors 204a and 204b and the second conductor 206 by insert molding leads to a reduction in the number of fixing members, which facilitates mounting on the printed circuit board 201.

  In addition, the first conductors 204a and 204b and the second conductor 206 are fastened and fixed to the housing 203 with screws 207, 208, 209, 210, and 211, so that electrical connection and mechanical fixing can be achieved. At the same time, the heat dissipation can be improved

  Further, the printed circuit board 201 and the second conductor 206 are fixed to the housing 203 by screws 211, so that the number of screws can be reduced and the tact can be improved.

  Moreover, since the voltage of the center tap which is the connection part of the secondary side windings 109 and 110 can be acquired and used as a control input without increasing the number of parts, the degree of freedom of control increases.

  In addition, even when the secondary windings 110 and 109 of the transformer 107 are arranged above and below the printed circuit board 201, one-way assembly can be realized, so that the assemblability can be improved.

  Further, by arranging the terminal block member 205 in the middle part of the MOSFETs 112, 113, 114, 115 and the transformer 107, the wiring length can be minimized, leading to an improvement in efficiency.

  The terminals of the first side conductors 204a and 204b, the second conductor 206, and the secondary windings 109 and 110 of the transformer 107 fixed to the terminal block member 205 by changing the height of the upper surface of the terminal block member 205. The parts can be designed to have the same height, and the cost can be reduced by simplifying the press work.

  Further, by not applying a solder resist to the pattern connecting the land 300 and the land 301, it is possible to apply a thick solder to the pattern, reduce the wiring resistance of the pattern, and suppress the heat generation of the printed circuit board.

Embodiment 2. FIG.
Next, an insulated DC / DC converter device according to Embodiment 2 of the present invention will be described. In the first embodiment, the first conductor and the second conductor have been described as an integral member by insert molding. However, in the second embodiment, they are formed by an integral member by insert molding. This is to explain a form that is not performed.

FIG. 6 is a diagram for explaining the isolated DC / DC converter device according to the second embodiment, and corresponds to FIG. FIG. 7 is a cross-sectional view showing a more detailed structure of FIG.
6 and 7, reference numerals 600, 601, and 602 denote rivets, and the first conductors 204 a and 204 b and the second conductor 206 are structurally fixed to the printed circuit board 201 by the rivets 600, 601, and 602. ing. Other configurations are the same as those in the first embodiment, and the same reference numerals are used in FIGS. 6 and 7 to omit the description.

  According to the second embodiment, the effect based on the first embodiment is obtained, and the first conductors 204a and 204b and the second conductor 206 are fixed to the printed circuit board 201 by the rivets 600, 601, and 602. Compared to the first embodiment, cost reduction can be achieved.

Embodiment 3 FIG.
Next, an insulated DC / DC converter device according to Embodiment 3 of the present invention will be described. In the first embodiment or the second embodiment, the connection between the first conductors 204a and 204b and the secondary windings 110 and 109 of the transformer 107 is described by the terminal block member 205. Form 3 explains the case where the terminal block member 205 is not used.

FIG. 8 is a diagram for explaining the isolated DC / DC converter device according to the third embodiment, and shows a part of the structure of the connection portion between the transformer 107 and the secondary side rectifying element 111 when the terminal block member is not used. It is sectional drawing shown.
In FIG. 8, the code | symbol 800 shows a thread part, and this thread part 800 is formed by giving a burring tap process to the 1st conductor 204a. Other configurations are the same as those in the first embodiment or the second embodiment, and the description thereof is omitted by giving the same reference numerals in FIG.

  According to the third embodiment, the effect based on the first embodiment is obtained, and the threaded portion 800 is formed by performing burring tap processing on the first conductor 204a. Therefore, the first embodiment or the second embodiment. Compared with, cost reduction can be achieved by reducing the number of parts.

  Further, since the first conductor 204a serves as a terminal block, the number of parts can be reduced, and the cost can be reduced.

As mentioned above, although Embodiment 1 thru | or Embodiment 3 of this invention was demonstrated, invention is not limited by these embodiments, In the range of the invention, each embodiment is combined, The embodiment can be changed or omitted as appropriate. For example, even in a diode rectification method using a diode as a rectifier on the secondary side, a configuration in which a rectifier is mounted on a printed circuit board as in the present invention can be considered. It is valid.

100 Full bridge circuit 101, 102, 103, 104 Switching element 105 Input capacitor 106 Resonant coil 107 Transformer 108 Primary side winding 109, 110 Secondary side winding 111 Secondary side rectifier circuit 112, 113, 114, 115 MOSFET
116 Smoothing coil 117 Output capacitor 118 Smoothing circuit 200 Insert molding member 201 Printed circuit board 201a Opening 202 Magnetic core 202a E-type core 202b I-type core 203 Cases 204a and 204b First conductor 205 Terminal block member 206 Second conductor 207, 208, 209, 210, 211 Screw 300, 301, 400, 401, 500, 501 Land 600, 601, 602 Rivet 800 Screw part A, B Input terminal C, D Output terminal G1, G2, G3 GND connection location

Claims (11)

A transformer having a high-voltage side primary winding and a low-voltage side secondary winding;
A switching element having first and second output terminals and a control terminal, which converts alternating current generated by the transformer into direct current;
A printed circuit board equipped with a control circuit that generates a control signal for controlling the switching element and inputs the control signal to the control terminal;
A housing for fixing the transformer, the switching element, and the printed circuit board;
In an insulated switching power supply device comprising:
A first conductor that electrically connects the first output terminal of the switching element and the low-voltage secondary winding, and the second output terminal of the switching element and the housing are electrically connected. A second conductor to be connected,
Insulated switching power supply device characterized in that connection between said switching element and said first conductor and connection between said switching element and said second conductor are connected via a pattern on said printed circuit board .   2. The insulated switching power supply device according to claim 1, wherein the first conductor and the second conductor are formed as an integral member while maintaining insulation with resin.   3. The insulated switching power supply device according to claim 1, wherein at least one of the first conductor and the second conductor is fixed to the printed circuit board. 4.   The insulated switching power supply device according to any one of claims 1 to 3, wherein the second conductor is fixed to the housing.   The insulated switching power supply device according to claim 4, wherein the second conductor is fixed to the casing together with the printed circuit board.   An inverter circuit that applies an alternating current to the high-voltage side primary winding; and a third conductor that electrically connects the high-voltage side primary winding and the inverter circuit. The insulated switching power supply device according to any one of claims 2 to 5, wherein the insulating switching power supply device is integrated with an integrated member of a conductor and the second conductor.   A terminal block member; and the low-voltage secondary winding is composed of first and second windings, and the first and second windings are arranged above and below the printed circuit board. The insulation according to claim 1, wherein at least one of the connection between the second winding and the first conductor is fastened together with the terminal block member. Type switching power supply.   The terminal block member is disposed in an intermediate portion between the switching element and the transformer, and an opening is provided in the printed board where the printed board and a female screw portion formed in the terminal block member overlap. The insulated switching power supply device according to claim 7.   The insulated switching power supply device according to claim 7 or 8, wherein the terminal block member includes at least three terminal block portions, and the height of one upper surface thereof is higher than the height of the other two upper surfaces. The first pattern on the printed circuit board that electrically connects the first output terminal and the first conductor, and the second pattern that electrically connects the second output terminal and the second conductor. The insulated switching power supply device according to any one of claims 1 to 9, wherein a solder resist is not applied to at least one of the second patterns on the printed circuit board.   The insulated switching power supply according to any one of claims 1 to 6, wherein a female screw part is formed in the first conductor, and the low-voltage secondary winding is connected to the female screw part. apparatus.

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