JP6379353B2 - DC-DC converter - Google Patents

Description

  The present invention relates to a DC-DC converter used for an electric vehicle and a plug-in hybrid vehicle.

  Electric vehicles and plug-in hybrid vehicles are equipped with a high-voltage storage battery used for power drive and a low-voltage storage battery for operating auxiliary equipment. Power conversion from a high-voltage storage battery to a low-voltage storage battery or high power from a low-voltage storage battery It is equipped with a DC-DC converter that converts power into a voltage storage battery.

  Hereinafter, a conventional DC-DC converter will be described with reference to the drawings. FIG. 3 is a perspective view of a circuit block showing the configuration of a conventional DC-DC converter. The conventional DC-DC converter includes a filter unit 3 connected to an input-side terminal 2 on a substrate 1, and a filter unit 3. The converter unit 4 connected to the output side of the output unit 5 and the output terminal 5 connected to the converter unit 4 were provided.

  In general, the converter unit 4 includes an inverter circuit (not shown) that generates an AC voltage from a high voltage storage battery (not shown) connected to the input side terminal 2, and a transformer (not shown) that transforms the AC voltage. A rectifier circuit (not shown) for rectifying the output voltage of the transformer, and a smoothing circuit (not shown) for smoothing the rectified voltage.

  Here, the converter unit 4 is arranged on the resin substrate unit 6 constituting the substrate 1, and the filter unit 3 is arranged on the metal substrate unit 7 constituting the substrate 1. In particular, in order to facilitate removal of noise generated in the filter unit 3, the metal substrate unit 7 is provided with the filter unit 3 on the metal substrate unit 7, and the metal substrate unit 7 is connected to the ground 8.

  For example, Patent Document 1 is known as prior art document information related to the invention of this application.

JP-A-5-161268

  However, in the conventional DC-DC converter, the filter unit 3 is disposed on the metal substrate unit 7 as a noise countermeasure in the filter unit 3. Here, when the filter unit 3 is disposed close to the converter unit 4, the filter unit 3 connected to the converter unit 4 is caused by noise radiated from the converter unit 4 and propagating in space or eddy current flowing through the housing. The original performance may not be sufficiently maintained due to the influence of electromagnetic noise generated.

  For this reason, it is not easy to arrange the filter unit 3 and the converter unit 4 close to each other, and as a result, there is a problem that it is difficult to reduce the size of the DC-DC converter.

  Accordingly, the present invention aims to reduce the size of a DC-DC converter.

  In order to achieve this object, the present invention includes an input terminal, an output terminal, and a power converter that converts a DC input voltage applied to the input terminal into a DC output voltage of a predetermined level and outputs the DC output voltage to the output terminal. A noise filter unit connected between the input terminal and the power conversion unit, a shield plate having an insulator on both sides, and a metal that houses the power conversion unit, the noise filter unit, and the shield plate A power conversion unit and the noise filter unit are stacked via the shield plate, and the negative output side of the power conversion unit, the shield plate, and the metal case are electrically connected. It is characterized by that.

  According to the present invention, the noise filter unit and the power conversion unit can be arranged close to each other, whereby the DC-DC converter can be reduced in size.

Cross-sectional schematic diagram of a DC-DC converter in an embodiment of the present invention The circuit diagram of the DC-DC converter in the embodiment of the present invention A perspective view of a circuit block of a conventional DC-DC converter

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

(Embodiment)
FIG. 1 is a schematic cross-sectional view showing the configuration of a DC-DC converter according to an embodiment of the present invention. The DC-DC converter includes an input terminal 9, an output terminal 10, a power conversion unit 11, a noise filter unit 12, a shield plate 13, and a metal case 14.

  Here, the power converter 11 converts the DC input voltage applied to the input terminal 9 into a DC output voltage of a predetermined level and outputs it to the output terminal 10. The noise filter unit 12 is connected between the input terminal 9 and the power conversion unit 11. Insulators 15 are provided on both sides of the shield plate 13. The metal case 14 houses the power conversion unit 11, the noise filter unit 12, and the shield plate 13.

  Here, the power conversion unit 11 and the noise filter unit 12 are stacked via a shield plate 13. And the negative electrode side output end 16 of the power conversion part 11, the shield board 13, and the metal case 14 are electrically connected.

  With the above-described configuration, the noise filter unit 12 detects noise that leaks from the power conversion unit 11 to the outside of the DC-DC converter via the input terminal 9 and noise that is about to enter the power conversion unit 11 from the outside of the power conversion unit 11. To reduce. And the noise filter part 12 is shielded from the radiation noise which the electric power conversion part 11 radiates | emits to surrounding space by the shield board 13. FIG. Then, the shield plate 13 that absorbs the radiation noise, the metal case 14 that electromagnetically shields the inside and outside of the DC-DC converter, and the negative output side 16 of the power conversion unit 11 are electrically connected, Noise is discharged to the grounding portion 16a outside the DC-DC converter. Here, the metal case 14 and the negative electrode side output end 16 are shown in an integrated configuration. However, the metal case 14 and the negative electrode side output end 16 may be composed of different elements that are electrically connected.

  As described above, even if the power conversion unit 11 and the noise filter unit 12 are disposed in a face-to-face positional relationship due to the shielding effect of the shield plate 13, the noise filter unit 12 is hardly affected by radiation noise. Therefore, the DC-DC converter can be reduced in size without being adversely affected by noise. In addition, noise mixing into the DC output voltage output from the output terminal 10 is suppressed.

  Hereinafter, the configuration of the DC-DC converter will be described in detail with reference to FIGS. 1 and 2. FIG. 2 is a circuit diagram of the DC-DC converter. The DC-DC converter converts voltage to supply power from the high voltage storage battery 17 to the low voltage storage battery 18.

  The power converter 11 includes a switching circuit 19 composed of an input capacitor C0 and transistors Q1 to Q4, a transformer 20, a rectifier circuit 21 composed of diodes D1 and D2, and a smoothing composed of an inductor L1 and a capacitor C1, an inductor L2 and a capacitor C2. A filter circuit 22 and a control circuit 23 for controlling the operation of the switching circuit 19 are included. The control circuit 23 monitors the output DC voltage of the smoothing filter circuit 22, and controls the operation of the switching circuit 19 based on this output DC voltage so that the output DC voltage becomes a predetermined value.

  The noise filter unit 12 is configured using a line filter 24 or the like, and removes normal mode noise and common mode noise. Further, the noise filter unit 12 is magnetically separated from the power conversion unit 11 by a shield plate 13.

  As a result, the line filter 24 is particularly difficult to receive high-frequency common mode noise radiated from the switching circuit 19. Therefore, the line filter 24 only needs to have a function corresponding to normal mode noise. As a result, the line filter 24 and the noise filter unit 12 are reduced in size, and as a result, the DC-DC converter can be reduced in size without being adversely affected by noise.

  Here, the power conversion unit 11 and the noise filter unit 12 are mounted on the first substrate 25 and the second substrate 26, respectively. Both the non-mounting surfaces of the first substrate 25 and the second substrate 26 face the shield plate 13. That is, the mounting surface of the first substrate 25 on which the power conversion unit 11 is mounted and the mounting surface of the second substrate 26 on which the noise filter unit 12 is mounted are arranged in opposite directions.

  In this case, the power conversion unit 11 is mounted on the lower surface of the first substrate 25 in the drawing, and the noise filter unit 12 is mounted on the upper surface of the second substrate 26 in the drawing. Thereby, magnetic interference between the power conversion unit 11 and the noise filter unit 12 is further less likely to occur.

  In addition to the above effects, the power conversion unit 11 is disposed close to the lower case 14b having a magnetic shielding effect, and the noise filter unit 12 is also disposed close to the upper case 14a having a magnetic shielding effect. Therefore, useless space in the metal case 14 can be omitted.

  Further, instead of the lower case 14b having a function as a housing, a heat radiating portion 27 having a heat radiating function may be provided after being electrically connected to the upper case 14a. And the heat radiation part 27 should just be made into a suitable shape and material for heat radiation. Here, the heat radiating portion 27 is exposed to the outside of the metal case 14 by being combined with the upper case 14a. Furthermore, the side opposite to the mounting surface of the shield plate 13 and the first substrate 25 in the power conversion unit 11, that is, the non-mounting side in the power conversion unit 11 may be brought into contact with the lower case 14 b or the heat dissipation unit 27.

  As a result, the heat dissipation function in the DC-DC converter is improved, and the heat dissipating part 27 that is thicker than the metal case 14 and has a large volume is used as a part of the metal case 14 so that it is connected to the negative output side 16. As a result, the resistance value of the part decreases, and the function related to grounding becomes accurate. Here, the heat radiating portion 27 and the negative electrode side output end 16 may be integrated, or the heat radiating portion 27 and the negative electrode side output end 16 may be composed of different elements that are electrically connected. .

  Here, although the element of the power conversion part 11 made to contact | abut to the lower case 14b or the thermal radiation part 27 is not shown in figure, it is desirable that they are a choke coil, a transformer, and a switching element. In general, the non-mounting side of the power conversion unit 11 is not necessarily a flat surface. At this time, the choke coil, the transformer, and the switching element, which are one of the devices that generate the most heat, are brought into contact with the heat radiating portion 27, so that the heat transfer and heat dissipation characteristics are improved.

  Further, the first substrate 25 on which the power conversion unit 11 is mounted and the second substrate 26 on which the noise filter unit 12 is mounted are arranged in a positional relationship separated by the shield plate 13. Here, the shield plate 13 may be in a positional relationship in contact with both the first substrate 25 and the second substrate 26, in a positional relationship in contact with either one, or in a positional relationship in which both are not in contact. .

  For example, when both the first substrate 25 and the second substrate 26 are in contact with the shield plate 13, it is desirable that the insulator 15 is provided on both surfaces of the shield plate 13 for insulation. At this time, the temperatures of the first substrate 25 and the second substrate 26 are easily equalized when both are in close contact with both sides of the shield plate 13. In order to prevent heat from staying in the first substrate 25 and the second substrate 26, the shield plate 13 is not only electrically connected but also mechanically connected directly to the metal case 14, or thermally. Connected to. As a result, the shield plate 13 functions not only as a shielding element but also as a heat transfer element. Therefore, the shield plate 13 can efficiently discharge the heat generated in the power conversion unit 11 and the noise filter unit 12 to the outside.

  Of course, since there is no gap between the shield plate 13 and both the first substrate 25 and the second substrate 26, the DC-DC converter can be reduced in size. Further, since the shield plate 13 is mechanically connected and fixed to the metal case 14, an area where the shield plate 13 inevitably blocks radiation noise emitted from the power conversion unit 11 is increased. As a result, the shielding effect by the shield plate 13 is further increased. Here, the direction in which the shield plate 13 extends to thermally connect to the metal case 14 coincides with the region where the choke coil, the transformer, and the switching element are arranged in the power conversion unit 11 although not shown here. It is desirable to make it. Furthermore, it is desirable to match the direction in which the shield plate 13 extends to a region where the choke coil and the winding portion of the transformer are exposed.

  Further, for example, when the first substrate 25 and the shield plate 13 are in contact with each other and the second substrate 26 and the shield plate 13 are not in contact with each other, the insulator 15 is provided on both surfaces of the shield plate 13 for insulation. It is desirable that

  At this time, the first substrate 25 is in close contact with one surface of the shield plate 13. Thereby, the heat generated in the power conversion unit 11 is released through the shield plate 13 to the inside of the metal case 14. However, most of the heat generated in the power conversion unit 11 is released to the outside of the DC-DC converter via the lower case 14 b or the heat dissipation unit 27. For this reason, the heat released to the inside of the metal case 14 through the shield plate 13 is a limited amount.

  Thereby, the heat generated in the power conversion unit 11 is not easily transmitted to the noise filter unit 12. Therefore, particularly when a device having a low heat-resistant limit temperature is applied to the noise filter unit 12, the shield plate 13 and the second substrate 26 are preferably brought into contact with each other through a space without being in close contact with each other. Furthermore, the shield plate 13 and the second substrate 26 are in close contact with each other in that the insulation between the input terminal 9 provided on the second substrate 26 and the output terminal 10 connected to the first substrate 25 is improved. It is better to face each other through the space without being arranged at.

  Again, in order to avoid heat from staying in the first substrate 25, the shield plate 13 is not only electrically connected but also mechanically connected directly or thermally connected to the metal case 14. Good. As a result, the shield plate 13 functions not only as a shielding element but also as a heat transfer element. Therefore, the shield plate 13 can efficiently discharge the heat generated in the power conversion unit 11 to the outside. That is, the shield plate 13 has both functions of magnetic shielding and thermal shielding.

  Furthermore, for example, when the first substrate 25 and the shield plate 13 are not in contact with each other, and the second substrate 26 and the shield plate 13 are in contact with each other, the insulator 15 is provided on both surfaces of the shield plate 13 for insulation. It is desirable to be provided.

  At this time, the second substrate 26 is in close contact with one surface of the shield plate 13. Thereby, most of the heat generated in the power conversion unit 11 is released to the outside of the DC-DC converter via the lower case 14 b or the heat dissipation unit 27. For this reason, among the heat generated in the power conversion unit 11, the heat released to the inside of the metal case 14 is a limited amount. And since the 2nd board | substrate 26 is closely_contact | adhered to one surface of the shield board 13, the heat | fever which generate | occur | produced in the noise filter part 12 is discharge | released inside the metal case 14. FIG. Thereby, the operation of the noise filter unit 12 is stabilized. In addition, the shield plate 13 is not only electrically connected but also mechanically connected directly to the metal case 14 in order to easily release the heat generated in the noise filter unit 12 to the outside of the DC-DC converter, or It is good to be connected thermally. Further, in order to insulate the input terminal 9 provided on the second substrate 26 from the output terminal 10 connected to the first substrate 25, the shield plate 13 and the first substrate 25 are not arranged in close contact with each other. It is better to face each other through a space.

  Again, in order to avoid heat from staying in the second substrate 26, the shield plate 13 is not only electrically connected but also mechanically connected directly or thermally connected to the metal case 14. Good. As a result, the shield plate 13 functions not only as a shielding element but also as a heat transfer element. Therefore, the shield plate 13 can efficiently discharge the heat generated in the noise filter unit 12 to the outside. That is, the shield plate 13 has both functions of magnetic shielding and thermal shielding.

  Although not shown here, the heat conversion unit 11 and the shield plate 13 or the power conversion unit 11 and the upper case 14a are thermally coupled by arranging the heat pipe in the DC-DC converter. May be strengthened.

  As described above, when the non-mounting side of the power conversion unit 11 is in contact with the lower case 14b and the heat dissipation unit 27, the heat dissipation of the power conversion unit 11 is improved. On the other hand, heat is likely to stay on the mounting side of the power conversion unit 11, that is, on the first substrate 25. Therefore, in particular, the heat pipe that is in close contact with the mounting surface side of the power converter 11 is preferably in close contact with the shield plate 13 and the upper case 14a.

  As a result, the power converter 11 actively dissipates heat on both the upper and lower sides. Therefore, even when the power conversion unit 11 needs to operate frequently or continuously, the power conversion unit 11 can operate while maintaining high reliability.

  Here, the heat pipe plays an auxiliary role with respect to the lower case 14b and the heat radiating portion 27 with respect to heat radiation and heat transfer. Therefore, the amount of heat released by the heat pipe may be smaller than that of the lower case 14 b or the heat radiating portion 27. For this reason, the cooling medium in the heat pipe may not be forcedly circulated from the outside.

  In particular, since the DC-DC converter is used for in-vehicle power supply, it is naturally mounted on the vehicle. And a certain amount of vibration always occurs in the vehicle as the vehicle runs or stops. For this reason, what is necessary is just to use the heat pipe which the fluidity | liquidity of a cooling medium produces by such a vibration.

  Specifically, a stirring ball (not shown) having an outer diameter smaller than the inner diameter of the heat pipe may be disposed in the heat pipe. This stirring ball enhances the fluidity of the cooling medium by the vibration of the vehicle, and as a result, enhances the heat dissipation function of the DC-DC converter.

  The DC-DC converter of the present invention has an effect of being easily miniaturized, and is useful in various electronic devices.

DESCRIPTION OF SYMBOLS 9 Input terminal 10 Output terminal 11 Power conversion part 12 Noise filter part 13 Shield plate 14 Metal case 14a Upper case 14b Lower case 15 Insulator 16 Negative side output terminal 16a Grounding part 17 High voltage storage battery 18 Low voltage storage battery 19 Switching circuit 20 Transformer 21 Rectifier circuit 22 Smoothing filter circuit 23 Control circuit 24 Line filter 25 First board 26 Second board 27 Heat radiation part

Claims (5)

An input terminal, an output terminal,
A power converter that converts the DC input voltage applied to the input terminal to a DC output voltage of a predetermined level and outputs the DC output voltage to the output terminal;
A noise filter unit connected between the input terminal and the power conversion unit;
A shield plate having an insulator on both sides;
A metal case for housing the power conversion unit, the noise filter unit, and the shield plate;
The power conversion unit and the noise filter unit are stacked via the shield plate,
A DC-DC converter in which a negative output side of the power converter, the shield plate, and the metal case are electrically connected.  2. The DC according to claim 1, wherein the shield plate is mechanically coupled to the metal case, and the negative output side of the power conversion unit, the shield plate, and the metal case are electrically and mechanically connected. DC converter. The power conversion unit is mounted on the first substrate and the noise filter unit is mounted on the second substrate,
The DC-DC converter according to claim 2, wherein the non-mounting surface of the first substrate and the non-mounting surface of the second substrate face the shield plate. A heat dissipating part in contact with the power conversion part;
3. The DC-DC converter according to claim 2, wherein the heat dissipating part is disposed on the opposite side of the power conversion part from the shield plate and exposed to the outside. 5. The DC-DC converter according to claim 4, wherein the heat dissipating part is electrically connected to a negative electrode side output end of the power conversion part, the shield plate, and the metal case.

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