JP3864938B2 - A metallized film capacitor, an in-vehicle drive inverter circuit using the same, and an automobile equipped with the in-vehicle drive inverter circuit. - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a capacitor element breaks in the worst case because the conventional film capacitor is used in the severe temperature condition and may also be used exceeding the thermally allowable value of the film capacitor when it receives all thermal factors. <P>SOLUTION: Temperature-proof characteristic can be improved by suppressing thermal influence received from the other equipment and heat generating factors of bus bar, adequately mounting capacitor forming components and processing the heat transferred from the external side, and suppressing current density. The film capacitor adaptable to mounting on an automobile can be obtained through improvement in the temperature-proof characteristic and reliability of the film capacitor for the temperature-proof characteristic, by lowering current density not to result in concentration at the shape of the connection bus bar and element bus bar of the film capacitor, and by extending the connection bus bar to enhance the heat radiating property through the layout of the bus bar itself. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a smoothing film capacitor used in an in-vehicle inverter power supply or an inverter circuit.

  In recent years, a film capacitor used for smoothing in an inverter circuit is required to have a high frequency ripple current of 70 to 90 A at a high voltage of 600 VDC or more, and a capacitor capacity has been increased to 2000 to 3000 μF, which is larger than a conventional film capacitor. It is starting to change. Furthermore, film capacitors have various strict requirements such as an increase in capacitor capacity in the same volume, weight reduction, low inductance, and high temperature resistance.

  Conventionally, a film capacitor has not been used for smoothing an inverter circuit. However, in recent years, the inverter voltage has been increased, and the conventional electrolytic capacitor has become unable to cope with the problem. The emergence of film capacitors is urgent.

  First, a conventional film capacitor for equipment will be described with reference to FIG. FIG. 4 shows a conventional film capacitor for equipment, wherein (a), (b), and (c) show a plan view, a front view, and a side view, respectively. In FIG. 4, 101 is a resin case, 102 is a capacitor element, 103 is a bus bar connected to the electrode surface of the capacitor element, 104 is a filling resin, and 105 is a resin case mounting leg.

  A capacitor having such a configuration is generally used as an indoor / indoor equipment capacitor. Such a capacitor has a small capacitor capacity and is usually composed of a single capacitor element. However, when the capacitor capacity is insufficient, a plurality of capacitors may be used as a composite.

  Further, the bus bar 103 connected to the capacitor element 102 shown in FIG. 4 is a case where there is almost no influence on heat generation, and has a structure in which the bus bar is directly taken out from the element 102. That is, the bus bar 103 is a single body, one end is attached to the electrode surface of the capacitor element 102, and the other end is taken out of the resin case 101 to serve as a connection terminal (see, for example, Patent Document 1).

The device film capacitor configured as described above has a general structure with respect to temperature and humidity in indoor and indoor specifications.
JP 2003-151848 A (FIG. 1)

  However, the film capacitor for smoothing used especially for the inverter circuit for vehicles has a severe use environment with respect to temperature, and if it receives all the heat factors described below, it may be used exceeding the heat allowable value of the film capacitor. There is a risk of destruction of the capacitor element. The five thermal effects that film capacitors receive from other devices will be described below.

  First, the usage environment of the capacitor used for in-vehicle use is in the vicinity of the engine room, the ambient temperature is −40 ° C. to 90 ° C., and it is used in a wide temperature range from low temperature to high temperature. Second, since it is installed on the immediate side of the inverter circuit to smooth the ripple current of the inverter circuit, it receives heat from the inverter circuit. Third, due to the high-frequency ripple high current generated in the inverter circuit, the connected bus bar itself generates heat and is conducted to the capacitor element through the bus bar having good heat conduction. Fourthly, the circuit heat generated in the inverter circuit is conducted to the capacitor element through the bus bar having good heat conduction. Fifth, since a film capacitor is used in common, there are a plurality of connection points with the inverter circuit.

  Of the thermal effects that the above-mentioned five film capacitors receive from other devices and the like, the first and second thermal effects are problems related to the entire structure, and it is difficult to find a solution for solving them with a single film capacitor. However, the third to fifth thermal effects can be found by solving the structure and configuration of the film capacitor.

  Next, two thermal effects caused by the film capacitor itself will be described.

  That is, the first is the heat generation of the capacitor element itself of the film capacitor, and the second is the heat generation according to the current density of the element portion bus bar connected to the capacitor element.

  Of the thermal effects of these two film capacitors themselves, as a measure for suppressing the temperature rise, there is a method of reducing the ripple current density of the electrode connection area of the capacitor element. There is also a measure to suppress self-heating by reducing the height of the capacitor element to reduce the equivalent series resistance.

  In addition, the second thermal effect can be countered by implementing a design that suppresses the current density of the element busbar, and the member used has a high thermal coefficient as a measure to promote heat dissipation from the entire capacitor. There is a way to incorporate into the configuration.

  That is, the problem to be solved by the present invention is that the bus bar connecting the capacitor element and the inverter circuit generates heat due to the high-frequency ripple large current generated from the inverter circuit connected to the capacitor. In the bus bar, the connection area of the portion connected to the inverter circuit is determined. When a high-frequency ripple high current is generated from the inverter circuit, the current density of the connection bus bar is increased and heat generation is increased. Furthermore, the connection portion bus bar has high thermal conductivity, and the circuit heat generated in the inverter circuit from the connection portion is thermally conducted to the capacitor element through the connection portion bus bar and the element portion bus bar.

  And in the conventional film capacitor, there is no distinction between the connection portion bus bar and the element portion bus bar, it is configured integrally in the above-described conventional resin case, and the bus bar current density remains in a very high state, Capacitor elements are greatly affected by heat.

  Therefore, the present invention aims to provide a film capacitor that can be used for in-vehicle use by suppressing the thermal effect and heat generation factor received from other devices, etc., and improving the reliability of the film capacitor. The heat effect and the heat generation factor received from the motor are suppressed, and the reliability of the film capacitor is increased to provide means that can be used for in-vehicle use.

That is, in order to solve the above-mentioned problem, the film capacitor of the present invention is arranged in a plurality so that a pair of electrode surfaces provided on both ends are provided with capacitor elements formed by winding or laminating a metallized film, A plurality of capacitor element groups each formed by connecting electrode surfaces with first and second element part bus bars each provided with a bus bar connecting portion are incorporated in an outer case, and are provided in the first and second element part bus bars. The bus bar connection part is arranged outside the outer case and filled with the filling resin, and the bus bar connection part arranged outside the outer case is connected to the connection part bus bar having the external connection part. The first element portion bus bars and the second element portion bus bars connected to the capacitor element group have the same potential .

Further, in the film capacitor of the present invention, the connection portion bus bar has a plurality of external connection portions, and the connection portion bus bar is connected to the plurality of element portion bus bars via the plurality of bus bar connection portions, The current path to whichever of the connection points is formed so that the current density is equal over the entire connection portion bus bar.

  As described above, the present invention suppresses the thermal influence and the heat generation factor of the bus bar, especially from other equipment, etc., with the configuration of the film capacitor, and improves the reliability of the film capacitor with respect to the temperature resistance. A capacitor can be provided.

  In addition, an in-vehicle drive inverter circuit using the metalized film capacitor of the present invention for smoothing or an automobile equipped with the in-vehicle drive inverter circuit is provided.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

(Embodiment 1)
FIG. 1 is a diagram showing a metallized film capacitor according to Embodiment 1 of the present invention, FIG. 2 is a diagram showing a configuration before connecting a connection bus bar according to Embodiment 1 of the present invention, and FIG. A top view, (b) shows a front view, and (c) shows a side view.

  1 and FIG. 2, 1 is a resinous outer case, 2 is a capacitor element in which a metallized film is wound or laminated, and electrode surfaces are provided on both end portions, and 21A and 21B are one side of the capacitor element 2. A plurality of capacitor element groups in which the electrode surfaces are arranged on the same plane, 31A to 31D are element part bus bars for connecting the electrode surfaces of the plurality of capacitor elements 2 to be on the same plane, and 5A is element part bus bars 31A and 31C. 5B is a connection part bus bar connected to the element part bus bars 31B and 31D, 3A is a bus bar connection point connecting the element part bus bar 31A and the connection part bus bar 5A, and 3B is an element part bus bar 31B and the connection part. A bus bar connection point for connecting the bus bar 5B, 3C connects the element bus bar 31C and the connection bus bar 5A. Busbar connection location, 3D is a busbar connection location connecting the element busbar 31D and the connection busbar 5B, 51A and 51C are external connection locations connecting the connection busbar 5A and the outside, and 51B and 51D are connection busbar 5B. External connection points 4 for connecting to the outside, 4 is a filling resin filled in the outer case 1, and 11 is a resin case leg.

  The configuration of the metallized film capacitor described above will be described below. Note that the film capacitor in this embodiment is used for smoothing an inverter circuit, and its satisfactory specifications are a voltage of 600 VDC or higher, a high-frequency ripple current at 70 to 90 A, and a capacitor capacity of 2000. ˜3000 μF, operating temperature conditions are those of ambient temperature −40 ° C. to 90 ° C.

  In the present embodiment, as shown in FIG. 2, first, capacitor element groups 21A and 21B are formed by arranging five capacitor elements 2 in two rows so that the electrode surfaces of the capacitor elements are on the same plane.

Furthermore, the electrode surfaces of the capacitor element groups 21 </ b> A and 21 </ b> B that are in the same plane are connected by the element bus bars 31 </ b> A to 31 </ b> D. Each capacitor element 2 has electrode connection portions on both end faces. In this embodiment, the capacitor elements are arranged in two rows, so that electrode connection for connecting the element bus bars 31A to 31D and the plurality of capacitor elements 2 is performed. There are four faces.

  The capacitor element groups 21 </ b> A and 21 </ b> B are arranged in two rows in the outer case 1, and the periphery thereof is filled with the filling resin 4.

  Further, as shown in FIG. 2, the end portions of the element portion bus bars 31 </ b> A to 31 </ b> D on the side opposite to the electrode connecting portion side are all protruded outward from the outer case 1, and the element portion bus bars 31 </ b> A and 31 </ b> C Busbar connection portions 3A to 3D for connecting to 5A and 5B are made to jump out of the outer case 1.

  As shown in FIG. 1, the bus bar connection points 3A and 3C are connected to the connection part bus bar 5A, and the connection part bus bar 5A further includes two external connection points 51A and 51C, which are electrically connected to the outside. Connected. Similarly, the element part bus bar connection points 3B and 3D are connected to the connection part bus bar 5B at the bus bar connection parts 3B and 3D, respectively, and the connection part bus bar 5B has two external connection parts 51B and 51D. Therefore, it is electrically connected to the outside.

  That is, the element bus bars 31A and 31C, 31B and 31D are electrically at the same potential, and are connected to the connection bus bars 5A and 5B, respectively.

  In addition, in the bus bar connection locations 3A to 3D, the method of connecting the element bus bars 31A to 31D and the connection bus bars 5A and 5B is not particularly limited, but is not particularly illustrated in the present embodiment, but is screwed. Connected.

  As shown in FIG. 1, the element portion bus bar connection locations 3 </ b> A to 3 </ b> D are provided outside the outer case 1.

  In this way, the element bus bars 31A to 31D are connected to the electrode surface of the capacitor element 2 without being routed into the outer case 1, and are then brought out of the outer case 1 at the shortest distance. By taking the shape connected to the element part bus bar connection locations 3A to 3D, heat generation of each bus bar due to the high current density due to the high frequency ripple can be suppressed.

  Further, by using a plurality of capacitor element groups as described above, the magnitude of the high-frequency ripple current flowing through each bus bar can be kept unchanged even when the capacitor capacity needs to be increased. For example, in the capacitor shown in FIG. 1, each of the capacitor element groups 21A and 21B is 100 μF and the capacity is 200 μF, but when the current density of the current flowing through the element bus bar is made equal and the capacity is 400 μF, Capacitor element groups having the same characteristics as those of the capacitor element groups 21A and 21B can be easily created by increasing the number of rows by two to four.

  In addition, the circuit heat generated by the inverter circuit connected to the capacitor is thermally conducted to the capacitor element 2 through the direct connection bus bars 5A and 5B and the element bus bars 31A to 31D, but the connection bus bars 5A and 5B and the element bus bar 31A. Since the bus bar connection portions 3A to 3D for connecting to 31D are provided outside the resin case 1, and the connection bus bars 5A and 5B higher than the ambient temperature can increase heat dissipation by natural convection of air, the capacitor element 2 The heat effect on can be reduced. Therefore, it is possible to provide a film capacitor that can suppress the heat influence and the heat generation factor, increase the reliability of the film capacitor, and can be used for in-vehicle use.

  In the present embodiment, the current density of the current flowing through the bus bar is the same. For example, the current density of the current flowing through the element bus bar 31A and the element bus bar 31C is the same as that of the external connection location 51A. As shown in FIG. 5, the connecting portion bus bar 5A is formed by branching in the respective directions from the external connection portion 51A. An example in the present embodiment will be described.

  In FIG. 1, a bus bar connection point 3A for connecting the connection part bus bar 5A and the element part bus bar 31A is in the vicinity of the external connection part 51A. On the other hand, the bus bar connection part 3C that connects the connection part bus bar 5A and the element part bus bar 31C is located away from the external connection part 51C.

  As shown in the schematic diagram of the current flowing through the bus bar in FIG. 3, when the capacitor of the present embodiment is connected to an external circuit such as an inverter circuit, two external connection points 51A and 51C provided in the connection bus bar 5A. Of these, there are two cases: when the current flows on the 51A side (the direction of the current is indicated by a solid line) and when the current flows on the 51C side (the direction of the current is indicated by a dotted line). There are two current paths flowing from the capacitor element to the outside as described above when not only for smoothing the inverter circuit but also for use as a filter for boosting the power supply.

  When the current flows to the 51C side, the current flowing from the bus bar connection part 3C of the connection part bus bar 5A to the external connection part 51C is the sum of the currents from both the element part bus bars 31A and 31C (in solid lines). Show). Further, when current flows to the 51A side, the currents from both the element bus bars 31A and 31C flow directly to the external connection location 51C separately without being added together. That is, the current flowing through the portion from the bus bar connection portion 3C to the external connection portion 51C of the connection portion bus bar 5A flows twice as much as the other portions.

  And the cross-sectional area with respect to the direction of the current from the bus bar connection part 3C to the external connection part 51C is doubled from the other parts so that the current density flowing through the connection part bus bar 5A is the same throughout. The cross-sectional area is adjusted by adjusting the thickness and width of the bus bar. Note that the heat generation in the bus bar is proportional to the square of the current density, and when the allowable heat generation amount of the bus bar is determined, the current density should be the same over the entire bus bar as in this embodiment. Therefore, the cost performance is optimal in terms of material cost.

  If the present embodiment is developed and a metal case is disposed outside the resin case 1, the heat dissipation of the capacitor itself can be further improved.

  Further, in the embodiment of the present invention, as shown in FIG. 1, the connection portion bus bars 5A and 5B formed outside the exterior case 1 are made substantially parallel to each other and face each other with a predetermined air gap therebetween. ing. By doing so, the inductance can be reduced by the interaction of the two bus bars.

  As another method, it is possible to suppress the inductance by inserting insulating paper between the connection bus bars 5A and 5B and bringing the connection bus bars 5A and 5B into close contact with each other.

Moreover, in embodiment of this invention, it is comprised so that the path | route which connects with element part bus bar 31A-31D through several external connection location 51A-51D and connection part bus bar 5A, 5B may become the minimum path | route. That is, for example, for the connection part bus bar 5B connected to the external connection part 51D shown as an example in FIG. 1, the bus bar connection part 3D connected to the element part bus bar 31D connected to the end of the capacitor element group 21B is externally connected. The film capacitor is configured to have a minimum path to the connection location 51D and suppresses the inductance.

  As described above, in the present embodiment, the capacitor elements are arranged in a plurality of rows, and the current density of the current flowing through the bus bar is made the same throughout, so that the portion connected to the inverter circuit is moved to the film capacitor side. Therefore, the current density of the connection busbar can be kept low with respect to the high-frequency ripple large current. Further, the connection portion bus bar is taken out from the resin case, and the connection portion bus bar itself is routed with improved heat dissipation, thereby reducing the thermal effect on the capacitor element.

  In addition, as a practical means for applying the film capacitor in the present embodiment, it is connected to an inverter circuit (not shown) for driving a vehicle driving motor for smoothing ripple current or the like, and is several hundred hertz to several tens of kilohertz. Smooth the high frequency current. Furthermore, an in-vehicle drive inverter circuit using the film capacitor for smoothing can be mounted on an automobile.

  The film capacitor of the present invention can be used for smoothing, and is particularly useful for smoothing an in-vehicle inverter circuit.

Configuration diagram (a) plan view, (b) front view, (c) side view of the first embodiment of the film capacitor of the present invention The block diagram before connecting the connection bus bar in Embodiment 1 of the film capacitor of this invention (a) Top view, (b) Front view, (c) Side view Schematic diagram of current flowing through busbar Configuration diagram of conventional film capacitor (a) plan view, (b) front view, (c) side view

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exterior case 2 Capacitor element 21A-21D Capacitor element group 31A-31D Element part bus bar 3A-3D Bus bar connection place 5A, 5B Connection part bus bar 51A-51D External connection place

Claims (7)

A plurality of capacitor elements formed by winding or laminating metallized films are arranged so that a pair of electrode surfaces provided at both ends are on the same plane, and the first and second elements are provided with bus bar connection portions between the electrode surfaces. A plurality of capacitor element groups each connected by a partial bus bar are built in the outer case, and the bus bar connecting points provided in the first and second element bus bars are arranged outside the outer case to fill the outer case. Filled with resin, and connected to the bus bar connection portion disposed outside the outer case, the connection portion bus bar having an external connection portion is connected, and the first element portion bus bars connected to the capacitor element groups are connected to each other. Metalized film capacitors with the same potential at each element bus bar . The connection portion bus bar has a plurality of external connection locations, and the connection portion bus bar is connected to the plurality of element portion bus bars via the plurality of bus bar connection locations, and the current path to which of the plurality of external connection locations Even if it exists, the metallized film capacitor of Claim 1 formed so that an electric current density might become equivalent over the said whole connection part bus-bar. The metallized film capacitor according to claim 2, wherein the connection portion bus bar is formed by changing a cross-sectional area facing the current direction so that a current density is equal throughout the connection portion bus bar. The metallized film capacitor according to any one of claims 1 to 3, wherein a metal case is disposed outside the outer case. 5. The capacitor according to claim 1, wherein a plurality of connection portion bus bars are arranged outside the outer case, and the plurality of connection portion bus bars are opposed to each other substantially in parallel with each other at a predetermined distance. A plurality of capacitor elements formed by winding or laminating metallized films are arranged so that a pair of electrode surfaces provided at both ends are on the same plane, and the first and second elements are provided with bus bar connection portions between the electrode surfaces. A plurality of capacitor element groups each connected by a partial bus bar are built in the outer case, and the bus bar connecting points provided in the first and second element bus bars are arranged outside the outer case to fill the outer case. Filled with resin, and connected to the bus bar connection portion disposed outside the outer case, the connection portion bus bar having an external connection portion is connected, and the first element portion bus bars connected to the capacitor element groups are connected to each other. In- vehicle drive inverter circuit using smoothing metallized film capacitors with the same potential for each element bus bar . A plurality of capacitor elements formed by winding or laminating metallized films are arranged so that a pair of electrode surfaces provided at both ends are on the same plane, and the first and second elements are provided with bus bar connection portions between the electrode surfaces. A plurality of capacitor element groups each connected by a partial bus bar are built in the outer case, and the bus bar connecting points provided in the first and second element bus bars are arranged outside the outer case to fill the outer case. Filled with resin, and connected to the bus bar connection portion disposed outside the outer case, the connection portion bus bar having an external connection portion is connected, and the first element portion bus bars connected to the capacitor element groups are connected to each other. A vehicle equipped with an in-vehicle drive inverter circuit that uses metallized film capacitors with the same potential between the element bus bars for smoothing.

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