JP2012134339A - Resin seal type capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable resin seal type capacitor that reduces the temperature in a region between capacitors which becomes a maximum temperature when charge and discharge currents flow.SOLUTION: Multiple film capacitors connecting with external terminals 16 to 19 are housed in a case 14, and the case 14 is filled with a sealing resin 15. As the multiple capacitors, two first capacitors 11, 12 are provided so as to be electrically connected in parallel through the external terminals 16 to 19. Further, a second capacitor 13, having impedance that is 10 times larger than impedance of the first capacitors 11, 12 for reducing heat generation compared to the first capacitors 11, 12, is provided. The second capacitor 13 is juxtaposed between the first capacitors 11, 12.

Description

  The present invention relates to a resin-sealed capacitor.

  Usually, in a vehicle such as an electric vehicle or a hybrid vehicle, the driving force by electric energy is to convert DC power supplied from a high-voltage battery into three-phase AC power by an inverter, thereby rotating the three-phase AC motor. Is gained by.

  As a smoothing capacitor used for such an inverter, a film capacitor and an electrolytic capacitor are known. In particular, a film capacitor is suitable for use in an inverter circuit having a high voltage of 450 V or more because it has a small loss and excellent ripple resistance and the dielectric film has a high withstand voltage.

  As shown in FIGS. 7 and 8, the conventional resin-encapsulated capacitor using this film capacitor has two smoothing capacitors 31 arranged adjacent to each other, and further has a side for one of the smoothing capacitors 31 for absorbing noise. A capacitor 33 is disposed and housed in a case 34 and filled with a sealing resin 35. As shown in FIG. 9, the smoothing capacitor 31 is connected to a pair of external terminals 36 to 39, and the noise absorbing capacitor 33 is connected to external terminals 38 and 39 connected to the adjacent smoothing capacitor 31.

  In addition, as prior art document information relevant to the invention of this application, for example, what is shown in Patent Document 1 is known.

JP 2007-12769 A

  However, in such a conventional resin-encapsulated capacitor, if a large charge / discharge current frequently flows through the capacitor due to switching, the resin-encapsulated capacitor placed in a high-temperature environment excessively rises in temperature. There was a problem that the temperature was exceeded and the insulation resistance deteriorated and the reliability was not sufficient.

  An object of the present invention is to solve such a conventional problem and to provide a resin-encapsulated capacitor having excellent reliability.

  To achieve the above object, the present invention provides a resin-sealed capacitor in which a plurality of capacitors connected to external terminals are housed in a case, wherein the plurality of capacitors can be electrically connected in parallel via the external terminals. A resin-sealed capacitor having two first capacitors provided and a second capacitor having a larger impedance than that of the first capacitor, the second capacitor being juxtaposed between the first capacitors.

  As described above, according to the present invention, the region between the capacitors is compared with the case where the first capacitors are adjacent to each other by placing the second capacitor having a larger impedance than the first capacitor between the first capacitors. Therefore, the temperature in the region between the capacitors, which is the maximum temperature, can be lowered, and the reliability of the resin-encapsulated capacitor can be improved.

Plane perspective view of resin-encapsulated capacitor in Embodiment 1 of the present invention AA sectional view of the resin-encapsulated capacitor of FIG. 1 is a perspective view of a resin-encapsulated capacitor according to Embodiment 1 of the present invention. Circuit diagram of resin-encapsulated capacitor in Embodiment 1 of the present invention Plane perspective view of resin-encapsulated capacitor in Embodiment 2 of the present invention AA sectional view of the resin-encapsulated capacitor of FIG. Plane perspective view of a conventional resin-encapsulated capacitor Front perspective view of a conventional resin-encapsulated capacitor Circuit diagram of a conventional resin-encapsulated capacitor

(Embodiment 1)
A resin-sealed capacitor according to Embodiment 1 of the present invention will be described.

  1 is a plan perspective view of a resin-encapsulated capacitor according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a perspective view of the resin-encapsulated capacitor according to Embodiment 1. FIG. 4 is a circuit diagram of the same.

  As shown in FIG. 1, in the resin-sealed capacitor 10a, a plurality of capacitors are housed in an insulating resin case 14, and the plurality of capacitors are covered with a sealing resin 15 as shown in FIGS. Is filled.

  The resin-encapsulated capacitor 10a is provided with at least one pair of external terminals, and the pair of external terminals includes a P pole and an N pole and is electrically connected to the capacitor. In the first embodiment, a pair of external terminals 16 and 17 and a pair of external terminals 18 and 19 are provided so as to protrude from the opening 14 a of the case 14.

  The plurality of capacitors includes first capacitors 11 and 12 provided so as to be electrically connected in parallel via external terminals 16 to 19, and a second capacitor 13 having a larger impedance than the first capacitors 11 and 12. Furthermore, the second capacitor 13 is juxtaposed between the first capacitors 11 and 12 and is disposed adjacent to the first capacitors 11 and 12. The same impedance of the two first capacitors 11 and 12 is preferable for mass production, but they may be different. Here, the impedance is a value at a frequency of 10 kHz.

  The first capacitors 11 and 12 and the second capacitor 13 are metallized film capacitors. The metallized film capacitor is a metal in which a vapor deposition electrode made of a metal vapor deposition film is provided on at least one surface of a dielectric film made of polypropylene or the like. The metallized part which becomes an external electrode is formed in the wound both end surfaces.

  In the resin-sealed capacitor in which the capacitors are arranged adjacent to each other, the region where the maximum temperature is reached is a region between the adjacent capacitors where heat is easily trapped. In the first embodiment, as shown in FIG. 12 is a region 26 between the outer peripheral side surface of 12 and the outer peripheral side surface of the second capacitor 13, and in the conventional example, is a region 40 between the smoothing capacitor 31 corresponding to the first capacitor as shown in FIG.

  When the first capacitors 11 and 12 and the second capacitor 13 are electrically connected in parallel via the external terminals 16 to 19 to charge and discharge the first capacitors 11 and 12 and the second capacitor 13, Since the charge / discharge current flowing through the second capacitor 13 is smaller than that of the first capacitors 11 and 12, the second capacitor 13 generates less heat than the first capacitors 11 and 12.

  Therefore, by arranging the second capacitor 13 between the first capacitors 11 and 12, it is possible to suppress an increase in the temperature of the region between the capacitors as compared to the case where the first capacitors 11 and 12 are adjacent to each other. it can. In order to prevent the temperature in the region between the capacitors from rising excessively, it is preferable that the impedance of the second capacitor 13 is 10 times or more that of the first capacitors 11 and 12.

  When the resin-encapsulated capacitor 10a is used for an inverter for driving a motor, the charge / discharge current is a pseudo sine wave whose main frequency region is around 10 kHz. At this time, by using the first capacitors 11 and 12 as a smoothing capacitor and the second capacitor 13 as an X capacitor or a Y capacitor for noise absorption or the like, the impedance characteristics of the resin-encapsulated capacitor 10a are improved and the capacitors are connected. The temperature of the area can be lowered.

  In order to improve the noise absorption performance of the resin-encapsulated capacitor 10a, the impedance of the second capacitor 13 is preferably 50 to 2500 times that of the first capacitors 11 and 12.

  One or more second capacitors can be provided between the first capacitors. When two or more second capacitors are provided, the second capacitors are electrically connected in series or in parallel when electrically connected in parallel via an external terminal. It can be a connection.

  In order to reduce the heat generation of the second capacitor, it is preferable to reduce the equivalent series resistance. By increasing the thickness of the vapor deposition electrode or shortening the distance between the capacitor elements metallicons than the first capacitors 11 and 12. The equivalent series resistance can be reduced.

  In the first embodiment, the first capacitors 11 and 12 and the second capacitor 13 have a flat cylindrical shape. As shown in FIG. 2, the first capacitors 11 and 12 have a flat cross section with the major axis direction being the bottom surface 14b of the case 14. The second capacitor 13 is disposed so that the major axis direction of the flat cross section is perpendicular to the bottom surface 14 b of the case 14.

  As described above, the first capacitors 11 and 12 and the second capacitor 13 are arranged so that the long diameters of the flat cross sections are orthogonal to each other, thereby reducing the size of the region between the capacitors of the resin-encapsulated capacitor 10a while reducing the temperature. be able to. In FIG. 2, two first capacitors are provided. However, three or more first capacitors may be provided, and the second capacitors may be juxtaposed between the first capacitors.

  The first capacitors 11 and 12 and the second capacitor 13 are close to each other with a gap therebetween. This distance is preferably set to 0.1 mm to 7 mm, and an excessive temperature rise can be suppressed while downsizing the resin-sealed capacitor 10a. Further, it is preferable that the gaps are filled with a sealing resin to improve heat dissipation. The first capacitors 11 and 12 and the second capacitor 13 may be in contact with each other.

  FIG. 4 is a circuit diagram of the resin-encapsulated capacitor according to the first embodiment, in which the first capacitors 11 and 12 and the second capacitor 13 are provided so as to be connected in parallel via external terminals 16 to 19. An example is shown.

  As shown in FIG. 4, the P and N poles of the two first capacitors 11 and 12 are connected to different external terminals 16 to 19, and the P and N poles of the second capacitor 13 are one of the first capacitors. The P pole of one capacitor 12 and the N pole of the other first capacitor 11 are electrically connected to each other. When the P poles and the N poles of the external terminals 16 to 19 are electrically connected to each other, the first capacitors 11 and 12 and the second capacitor 13 are connected in parallel.

  Further, with the circuit configuration shown in FIG. 4, the characteristics of the first capacitor and the second capacitor can be individually inspected even after resin sealing.

  As shown in FIG. 1, the external terminals 16 to 19 are provided on one side of the case 14, and the bus bars 20 and 22 of the first capacitors 11 and 12 are led out along the end surfaces of the first capacitors 11 and 12, respectively. The other bus bars 21, 23 are connected to the external terminals 16, 18, and the other bus bars 21, 23 are substantially triangular so that the width decreases from one metallicon part toward the external terminals 17, 19 along the upper surface of the first capacitors 11, 12. Are connected to the external terminals 17 and 19, respectively.

  The bus bar 25 of the second capacitor 13 is joined to the bottom surface side of the substantially triangular bus bar 21 along the side surface of the first capacitor 11, and the other bus bar 24 of the second capacitor 13 is connected to the second capacitor 13. Is joined to the bus bar 22 of the other first capacitor 12 along the end surface of the first capacitor 12.

  The sealing resin 15 is an insulating resin such as an epoxy resin, and more preferably has excellent heat resistance, moisture resistance, and thermal conductivity.

(Embodiment 2)
A resin-encapsulated capacitor according to Embodiment 2 of the present invention will be described.

  5 is a plan perspective view of the resin-encapsulated capacitor according to the second embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5. The same reference numerals are given to the same parts as those of the first embodiment. The description will be omitted, and only different configurations will be described with reference to the drawings.

  As shown in FIGS. 5 and 6, the resin-encapsulated capacitor 10 b has a recess 28 formed on the bottom surface 27 b side of the case 27 formed so as to bend a case plate having a predetermined thickness inside the case 27. Is. The concave portion 28 is inserted between the first capacitors 11 and 12, and the first capacitors 11 and 12 are provided close to the side surface of the concave portion 28 on the inner peripheral side of the case 27, and the outer peripheral side of the case 27 in the concave portion 28 is opened. A gap is provided.

  The recess 28 is arranged in the axial direction of the flat cylindrical shape of the second capacitor 13 so as to be juxtaposed with the second capacitor 13, and the apex 28 a of the recess 28 is the first capacitor 11 on the opening 27 a side of the case 27. , 12 are provided so as to overlap or exceed a straight line connecting the upper surfaces of the two.

  By providing the recess 28 in this manner, the heat dissipation in the high temperature region between the capacitors can be enhanced, and the amount of the sealing resin can be reduced and the weight can be reduced.

  In FIG. 5, the recess 28 is provided on one side of the case 27. However, two recesses may be provided on both sides facing each other, and the second capacitor 13 may be juxtaposed between the two recesses. The sex can be further enhanced. Further, a gap is provided between the inner peripheral side of the case 27 in the recess 28 and the first capacitor 11, 12 and the second capacitor 13, respectively, and it is preferable that the gap is filled with the sealing resin 15. Can be improved.

(Example)
The resin-encapsulated capacitors of Example 1, Example 2, and Comparative Example will be described.

  The resin-encapsulated capacitor of Example 1 has the structure of Embodiment 1 shown in FIG. 1, Example 2 has the structure of Embodiment 2 shown in FIG. 5, and the comparative example has the conventional structure shown in FIG. belongs to.

  In Example 1, the same polypropylene is used as the dielectric film of the first capacitor and the second capacitor. The second capacitor has an impedance of 10 kHz that is 300 times that of the first capacitor and an equivalent series resistance of 2 of the first capacitor. The heat generation of the capacitor was adjusted by ˜5 times. The allowable temperature of the first capacitor and the second capacitor is 105 ° C.

  The resin-encapsulated capacitor of Example 2 was the same as Example 1 except that a recess was provided on the bottom side of the case.

  For the comparative example, the smoothing capacitor and the noise absorbing capacitor are the first capacitor and the second capacitor of the first embodiment, respectively, and the two first capacitors and the second capacitor are provided in parallel. .

  In the first and second embodiments, the gap between the first capacitor and the second capacitor was 0.5 mm to 1 mm, and the distance between the first capacitors was 20 mm to 22 mm. The distance between the first capacitors in the comparative example was arranged to be 3 mm to 4 mm.

  Next, the 1st capacitor | condenser of Example 1, Example 2, and the comparative example and the 2nd capacitor | condenser were connected in parallel via the external terminal. Next, the ambient temperature around the resin-encapsulated capacitor was set to 70 ° C. to 90 ° C., and a ripple current of 10 kHz was applied so that the maximum current value was 60 A, and the maximum value of the temperature of the resin-encapsulated capacitor was measured. .

  As a result, when the difference from the maximum value of the temperature of the resin-encapsulated capacitor based on the environmental temperature is the overheating temperature ΔT, the first and second embodiments are in the region between the first capacitor and the second capacitor. The maximum temperature was reached, and ΔT was 4.7 ° C. and 4.2 ° C., respectively. On the other hand, the comparative example had a maximum temperature in the region between the first capacitors, and ΔT was 7 ° C.

  As described above, the temperature of the region where the maximum temperature is reached is lowered by placing the second capacitor having a low temperature between the first capacitors having large heat generation as in the first and second embodiments, as compared with the comparative example. Can do.

  The resin-encapsulated capacitor of the present invention has the effect of lowering the temperature in the region where the maximum temperature is reached and increasing the reliability, and is useful for a capacitor unit having a plurality of capacitors.

10a, 10b Resin-sealed capacitor 11, 12 First capacitor 13 Second capacitor 14, 27 Case 14a, 27a Opening 14b, 27b Bottom 15 Sealing resin 16, 17, 18, 19 External terminals 20, 21, 22, 23, 24, 25 Busbar 26 area

Claims (4)

In a resin-encapsulated capacitor in which a plurality of capacitors connected to external terminals are housed in a case, the plurality of capacitors are provided with two first capacitors that can be electrically connected in parallel via the external terminals; A resin-encapsulated capacitor having a second capacitor having a larger impedance than the first capacitor, the second capacitor being juxtaposed between the first capacitors. The resin-encapsulated capacitor according to claim 1, wherein the impedance of the second capacitor is 10 times or more that of the first capacitor. 2. The resin-encapsulated capacitor according to claim 1, wherein the first and second capacitors have a flat cylindrical shape, and are provided so that the long diameters of the flat cross sections of the first capacitor and the second capacitor are perpendicular to each other. The resin-encapsulated capacitor according to claim 1, wherein a concave portion is provided in the case, and the concave portion is inserted between the first capacitors and juxtaposed with the second capacitor.

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