JP2024091741A - Film capacitor and power conversion device - Google Patents

Abstract

To provide a film capacitor which can reduce inductance.SOLUTION: A film capacitor C comprises a plurality of film capacitor elements, a first bus bar of first polarity, a second bus bar of second polarity, and a case 40, in which the first bus bar comprises a first input terminal 22 and a first pole output terminal 23, and the second bus bar comprises a second pole input terminal 32 and second pole output terminals 33. The second pole output terminals 33 are arranged on both sides of the first pole output terminal 23 in each of at least two phases, and the second pole output terminals 33 in different phases adjacent to each other become communized common terminals.SELECTED DRAWING: Figure 2

Description

The present invention relates to a film capacitor and a power conversion device equipped with the film capacitor.

Conventionally, power conversion devices that supply three-phase AC power to the motors of electric vehicles such as hybrid cars and electric automobiles are known. The power conversion device includes a DC/DC converter, an inverter, and a film capacitor. The DC/DC converter boosts and outputs DC power supplied from a battery, and the inverter converts the boosted DC power output by the DC/DC converter into three-phase AC power and supplies it to the motor. The film capacitor is provided between the DC/DC converter and the inverter, and functions as a smoothing capacitor.

As shown in FIG. 6(A), the output terminals of the film capacitor are composed of the U-phase terminal, V-phase terminal, and W-phase terminal of the cathode (N pole) and the U-phase terminal, V-phase terminal, and W-phase terminal of the anode (P pole), with terminals of the same phase adjacent to each other and the cathode terminals and anode terminals arranged alternately (see, for example, Patent Document 1).

JP 2013-251351 A

In the above film capacitor, the inductance of each terminal constituting the output terminal is determined by the width w of each terminal, and the larger the width w, the smaller the inductance. However, if the terminals are placed close to each other, the width w of each terminal cannot be sufficiently secured, resulting in a problem of large inductance.

On the other hand, if there is sufficient clearance between the output terminals and the width of each terminal is increased, the distance between the fastening through holes TH formed in each terminal (the distance between through holes TH of different polarities and the same phase) increases, and the inductance between each phase increases. For example, as shown in FIG. 6(B), if the width of each terminal is increased from w to w', the distance between through holes TH of different polarities and the same phase increases from d to d', resulting in a problem of increased inductance between each phase.

The present invention was made in consideration of the above circumstances, and its objective is to provide a film capacitor that can achieve low inductance and a power conversion device equipped with the film capacitor.

In order to solve the above problems, the film capacitor according to the present invention comprises:
a plurality of film capacitor elements each having a first electrode and a second electrode;
A first bus bar having a first polarity connected to the first electrode;
a second bus bar having a second polarity connected to the second electrode;
A film capacitor comprising:
the first bus bar includes a first pole first phase terminal for a first phase and a first pole second phase terminal for a second phase, which constitute a first pole main plate, a first pole input terminal, and a first pole output terminal;
Equipped with
the second bus bar includes a second pole first phase terminal for the first phase and a second pole second phase terminal for the second phase, which constitute a second pole main plate, a second pole input terminal, and a second pole output terminal;
Equipped with
the second-pole first-phase terminal includes a first terminal and a second terminal that are drawn out across the first-pole first-phase terminal,
the second pole second phase terminal includes a third terminal;
The second terminal and the third terminal are integrated into a single first common terminal.

With this configuration, the second pole first phase terminal has a first terminal and a second terminal that are pulled out from between the first pole first phase terminal, so the width of the second pole first phase terminal can be increased without increasing the distance between the output part of the second pole first phase terminal (e.g., a through hole for fastening) and the output part of the first pole first phase terminal (e.g., a through hole for fastening). As a result, low inductance can be achieved.

Furthermore, with this configuration, the second terminal and the third terminal are combined into a single common first terminal, so the terminal width can be made larger, leading to even lower inductance.

In the above film capacitor,
The first bus bar includes a plurality of the first pole output terminals,
The second bus bar may be configured to include the second pole output terminals in the same number as the first pole output terminals.

In order to solve the above problems, a power conversion device according to the present invention comprises:
A power conversion device that converts DC power supplied from a DC power source into AC power and supplies the AC power to a load,
a DC/DC converter that boosts the DC power and outputs boosted DC power;
a film capacitor according to the present invention that smoothes the boosted DC power and outputs DC power for at least two phases;
an inverter that generates the at least two-phase AC power based on the at least two-phase DC power;
The present invention is characterized by comprising:

The present invention provides a film capacitor that can achieve low inductance and a power conversion device that includes the film capacitor.

1 is a block diagram of a power conversion device according to the present invention. 1 is a perspective view of a film capacitor according to the present invention; 1 is an exploded perspective view of a film capacitor according to the present invention; 1A is a diagram showing an output terminal of an N bus bar, and FIG. 1B is a diagram showing an output terminal of a P bus bar. A diagram showing the distance between through holes formed in the output terminals of the N bus bar and the P bus bar. 1A and 1B are diagrams for explaining problems with a conventional film capacitor.

Hereinafter, an embodiment of a film capacitor and a power conversion device according to the present invention will be described with reference to the attached drawings. Note that the forward/backward direction X, the left/right direction Y, and the up/down direction Z indicated by the arrows in the drawings are linear directions that are perpendicular to each other.

Figure 1 shows a power conversion device 1 according to one embodiment of the present invention. The power conversion device 1 includes a DC/DC converter A, inverters B1 and B2, a film capacitor C according to one embodiment of the present invention, and a control circuit D.

The power conversion device 1 is mounted on an electric vehicle such as a hybrid vehicle or an electric car, and converts DC power supplied from a battery 2 (corresponding to the "DC power source" of the present invention) into AC power and supplies it to motors 3 and 4 (corresponding to the "load" of the present invention).

Under the control of the control circuit D, the DC/DC converter A boosts the DC power input from the battery 2 and outputs the boosted DC power to the film capacitor C. The DC/DC converter A can be composed of, for example, an insulating transformer, a switching circuit on the primary side, and a rectifying and smoothing circuit on the secondary side.

Under the control of the control circuit D, the inverter B1 converts the three-phase DC power input from the film capacitor C into three-phase AC power and outputs the three-phase AC power to the motor 3. Similarly, under the control of the control circuit D, the inverter B2 converts the three-phase DC power input from the film capacitor C into three-phase AC power and outputs the three-phase AC power to the motor 4. The inverters B1 and B2 each include a U-phase switch circuit that generates U-phase AC power, a V-phase switch circuit that generates V-phase AC power, and a W-phase switch circuit that generates W-phase AC power. Each switch circuit can be composed of, for example, switching elements connected in series.

In this embodiment, the inverters B1 and B2 have input terminals corresponding to the output terminals of the film capacitors C. Specifically, the switch circuits of each phase of the inverters B1 and B2 have an N input terminal, a first P input terminal, and a second P input terminal. For example, the first P input terminal and the second P input terminal are connected to one end of the switch circuit, and the N input terminal is connected to the other end of the switch circuit.

As described above, the control circuit D controls the DC/DC converter A and the inverters B1 and B2. The control circuit D can be configured as an analog control circuit, a digital control circuit including a microcontroller, or a combination of both.

Film capacitor C is provided between DC/DC converter A and inverters B1 and B2, and functions as a smoothing capacitor. Figure 2 shows a perspective view of film capacitor C, and Figure 3 shows an exploded perspective view of film capacitor C.

The film capacitor C includes a capacitor element portion 10, an N bus bar 20 corresponding to the "first bus bar of first polarity" of the present invention, a P bus bar 30 corresponding to the "second bus bar of second polarity" of the present invention, a case 40, an insulating portion 50, and a sealing resin 60. Note that the sealing resin 60 is omitted in FIG. 3.

The capacitor element section 10 has eight film capacitor elements 11 (corresponding to the "film capacitor elements" of the present invention) that function as smoothing capacitors.

Film capacitor element 11 is formed by overlapping and winding a pair of metallized films, each having a metal film formed on the surface of the dielectric film as internal electrodes (cathode, anode), with metallikon sections formed as external electrodes at both winding ends. One metallikon section (corresponding to the "first electrode" of the present invention) is connected to the internal electrode (cathode) of one metallized film, and the other metallikon section (corresponding to the "second electrode" of the present invention) is connected to the internal electrode (anode) of the other metallized film. Film capacitor element 11 is placed in case 40 with the first electrode on the lower side and the second electrode on the upper side.

The N busbar 20 is an electrode terminal component formed by processing a metal plate, and is a busbar for the cathode. The N busbar 20 includes an N main plate 21, which corresponds to the "first pole main plate" of the present invention, an N input terminal 22, which corresponds to the "first pole input terminal" of the present invention, and an N output terminal 23, which corresponds to the "first pole output terminal" of the present invention.

The N main plate 21 is housed in the case 40 and is connected to the first electrode on the lower side of the film capacitor element 11. The N input terminal 22 is pulled out from the front end of the N main plate 21 and exposed to the front surface of the case 40, and is connected to the output terminal for the cathode of the DC/DC converter A. The N output terminal 23 is pulled out from the left and right ends of the N main plate 21 to the outside of the case 40. Details of the N output terminal 23 will be described later.

The P busbar 30 is an electrode terminal part formed by processing a metal plate, and is a busbar for the anode. The P busbar 30 includes a P main plate 31, which corresponds to the "second pole main plate" of the present invention, a P input terminal 32, which corresponds to the "second pole input terminal" of the present invention, and a P output terminal 33, which corresponds to the "second pole output terminal" of the present invention.

The P main board 31 is housed in the case 40 and is connected to the upper second electrode of the film capacitor element 11. The P input terminal 32 is pulled out from the front end of the P main board 31 and exposed on the front surface of the case 40 adjacent to the N input terminal 22, and is connected to the anode output terminal of the DC/DC converter A. The P output terminals 33 are pulled out from the left and right ends of the P main board 31 to the outside of the case 40. Details of the P output terminals 33 will be described later.

The case 40 is a housing formed from an insulating resin and includes a bottom 41 and a peripheral wall 42. The bottom 41 and the peripheral wall 42 are integrally formed from the same insulating resin.

The bottom 41 is provided so as to be located below the N main plate 21 of the N bus bar 20, and the peripheral wall portion 42 is provided so as to surround the sides (front, rear, left, and right) of the N main plate 21. In other words, the bottom 41 and the peripheral wall portion 42 form a storage space for storing the N main plate 21 of the N bus bar 20, the capacitor element portion 10, and the P main plate 31 of the P bus bar 30.

The insulating section 50 is provided to prevent a short circuit between the N bus bar 20 and the P bus bar 30. The insulating section 50 includes a first insulating member 51, a second insulating member 52, and a third insulating member 53. The first insulating member 51 is disposed between the front end of the N main board 21 and the front end of the P main board 31. The second insulating member 52 is disposed between the left end of the N main board 21 and the left end of the P main board 31. The third insulating member 53 is disposed between the right end of the N main board 21 and the right end of the P main board 31.

The sealing resin 60 is a resin for protecting the capacitor element portion 10 housed in the storage space inside the case 40. The sealing resin 60 is, for example, a potting resin such as epoxy resin that is filled into the case 40 in a predetermined amount using a dispenser and then hardened.

Figure 4 (A) shows the N output terminal 23 on the left side of the N bus bar 20, and Figure 4 (B) shows the P output terminal 33 on the left side of the P bus bar 30. Note that the N output terminal 23 on the right side of the N bus bar 20 has the same configuration as the N output terminal 23 on the left side, and the P output terminal 33 on the right side of the P bus bar 30 has the same configuration as the P output terminal 33 on the left side.

The N output terminal 23 includes an N output terminal 23U for the U phase, which corresponds to the "first pole first phase terminal" of the present invention, an N output terminal 23V for the V phase, which corresponds to the "first pole second phase terminal" of the present invention, and an N output terminal 23W for the W phase, which corresponds to the "first pole third phase terminal" of the present invention. The N output terminals 23U, 23V, and 23W have predetermined widths w1, w2, and w3, respectively. In this embodiment, w1 = w2 = w3.

The N output terminals 23U, 23V, and 23W are formed with through holes TH (round holes in this embodiment) as output sections for fastening to the N input terminals of each phase of the inverter B1. The N output terminal 23U is connected to the N input terminal of the U-phase switch circuit of the inverter B1. The N output terminal 23V is connected to the N input terminal of the V-phase switch circuit of the inverter B1. The N output terminal 23W is connected to the N input terminal of the W-phase switch circuit of the inverter B1.

The P output terminals 33 include U-phase P output terminals 33U, 33U' corresponding to the "second pole first phase terminal (first terminal, second terminal)" of the present invention, V-phase P output terminals 33V, 33V' corresponding to the "second pole second phase terminal (third terminal, fourth terminal)" of the present invention, and W-phase P output terminals 33W, 33W' corresponding to the "second pole third phase terminal (fifth terminal, sixth terminal)" of the present invention. However, P output terminals 33U' and P output terminals 33V are a single common first common terminal 33UV, and P output terminals 33V' and P output terminals 33W are a single common second common terminal 33VW.

The P output terminal 33U and the P output terminal 33W' have predetermined widths w4 and w5, respectively. In this embodiment, w4 = w5, and w4 (= w5) is smaller than w1 (= w2 = w3).

The first common terminal 33UV and the second common terminal 33VW have predetermined widths w6 and w7, respectively. In this embodiment, w6=w7. w6 is greater than twice the width w4 of the P output terminal 33U. w7 is greater than twice the width w5 of the P output terminal 33W'.

The P output terminal 33U, the first common terminal 33UV, the second common terminal 33VW, and the P output terminal 33W' are formed with through holes TH (round holes in this embodiment) as output parts for fastening to the P input terminals of each phase of the inverter B1. The first common terminal 33UV and the second common terminal 33VW each have two through holes TH.

The P output terminal 33U is connected to the first P input terminal of the U-phase switch circuit of the inverter B1. The first common terminal 33UV is connected to the second P input terminal of the U-phase switch circuit of the inverter B1 on the P output terminal 33U side, and is connected to the first P input terminal of the V-phase switch circuit of the inverter B1 on the second common terminal 33VW side. The second common terminal 33VW is connected to the second P input terminal of the V-phase switch circuit of the inverter B1 on the first common terminal 33UV side, and is connected to the first P input terminal of the W-phase switch circuit of the inverter B1 on the P output terminal 33W' side. The P output terminal 33W' is connected to the second P input terminal of the W-phase switch circuit of the inverter B1.

As shown in FIG. 5, if the distance between the through hole TH of the P output terminal 33U and the through hole TH of the N output terminal 23U is d1, and the distance between the through hole TH of the N output terminal 23U and the through hole TH for the U phase of the first common terminal 33UV is d1', then d1=d1'. If the distance between the through hole TH for the V phase of the first common terminal 33UV and the through hole TH of the N output terminal 23V is d2, and the distance between the through hole TH of the N output terminal 23V and the through hole TH for the V phase of the second common terminal 33VW is d2', then d2=d2'. If the distance between the through hole TH for the W phase of the second common terminal 33VW and the through hole TH of the N output terminal 23W is d3, and the distance between the through hole TH of the N output terminal 23W and the through hole TH of the P output terminal 33W' is d3', then d3=d3'.

In other words, the first common terminal 33UV is formed with through holes TH for the U phase and the V phase such that d1 = d1' and d2 = d2'. Similarly, the second common terminal 33VW is formed with through holes TH for the V phase and the W phase such that d2 = d2' and d3 = d3'.

In the film capacitor C according to this embodiment, the P output terminals 33 (33U, 33U', 33V, 33V', 33W, 33W') are arranged on both sides of the N output terminals 23 (23U, 23V, 23W) in each phase, so that the terminal width of the P output terminals 33 can be increased without increasing the distance between the output parts of opposite polarity (between the through holes TH) in each phase. As a result, low inductance can be achieved.

Furthermore, in the film capacitor C according to this embodiment, the P output terminal 33U' and the P output terminal 33V are combined into a single first common terminal 33UV, and the P output terminal 33V' and the P output terminal 33W are combined into a single second common terminal 33VW, so that the terminal width of the P output terminal 33 can be made larger. As a result, the inductance can be further reduced.

In addition, by using the first common terminal 33UV, the P output terminal 33U' and the P output terminal 33V are necessarily located on the same plane, which makes it easier to determine the dimensions of the terminals (e.g., adjust the height of the terminals) and reduces the complexity of the assembly jig compared to when the P output terminals 33U' and 33V are provided separately. The same effect is achieved with the second common terminal 33VW.

[Modification]
Although the embodiments of the film capacitor and the power conversion device according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments.

The film capacitor according to the present invention comprises a plurality of film capacitor elements, a first bus bar of a first polarity, and a second bus bar of a second polarity. The first bus bar comprises a first pole main plate, a first pole input terminal, and a first pole output terminal for at least two phases, and the second bus bar comprises a second pole main plate, a second pole input terminal, and a second pole output terminal for at least two phases. The configuration can be modified as appropriate as long as the second pole output terminals are arranged on both sides of the first pole output terminal in each of the at least two phases, and the second pole output terminals of adjacent different phases are shared to form a common terminal.

The film capacitor according to the present invention may be a so-called resinless film capacitor that does not have the sealing resin 60. The film capacitor according to the present invention may also be a so-called caseless film capacitor in which the capacitor element portion 10, the N main plate 21 of the N bus bar 20, and the P main plate 31 of the P bus bar 30 are covered with an exterior resin.

In the above embodiment, the film capacitor is compatible with three phases, U, V, and W, but the film capacitor according to the present invention may be compatible with two phases or four or more phases.

In the above embodiment, the P output terminals 33 (33U, 33U', 33V, 33V', 33W, 33W') are arranged on both sides of the N output terminals 23 (23U, 23V, 23W) in each phase, but the N output terminals 23 may be arranged on both sides of the P output terminal 33 in each phase. In that case, instead of the P bus bar 30, the N bus bar 20 is configured to have a first common terminal and a second common terminal.

The power conversion device according to the present invention is a power conversion device that converts DC power supplied from a DC power source into AC power and supplies it to a load, and can be modified as appropriate as long as it includes a DC/DC converter that boosts the DC power and outputs boosted DC power, a film capacitor according to the present invention that smoothes the boosted DC power and outputs at least two-phase DC power, and an inverter that generates at least two-phase AC power based on the at least two-phase DC power.

A DC/DC converters B1, B2 Inverter C Film capacitor D Control circuit 1 Power conversion device 2 Batteries 3, 4 Motor 10 Capacitor element section 11 Film capacitor element 20 N bus bar 21 N main plate 22 N input terminal 23 N output terminal 30 P bus bar 31 P main plate 32 P input terminal 33 P output terminal 33UV First common terminal 33VW Second common terminal 40 Case 41 Bottom 42 Peripheral wall section 50 Insulating section 51 First insulating member 52 Second insulating member 53 Third insulating member 60 Sealing resin

Claims (3)

a plurality of film capacitor elements each having a first electrode and a second electrode;
A first bus bar having a first polarity connected to the first electrode;
a second bus bar having a second polarity connected to the second electrode;
A film capacitor comprising:
the first bus bar includes a first pole first phase terminal for a first phase and a first pole second phase terminal for a second phase, which constitute a first pole main plate, a first pole input terminal, and a first pole output terminal;
Equipped with
the second bus bar includes a second pole first phase terminal for the first phase and a second pole second phase terminal for the second phase, which constitute a second pole main plate, a second pole input terminal, and a second pole output terminal;
Equipped with
the second-pole first-phase terminal includes a first terminal and a second terminal that are drawn out across the first-pole first-phase terminal,
the second pole second phase terminal includes a third terminal;
A film capacitor, wherein the second terminal and the third terminal are combined into a single first common terminal. The first bus bar includes a plurality of the first pole output terminals,
The film capacitor according to claim 1 , wherein the second bus bar includes the second pole output terminals in the same number as the first pole output terminals. A power conversion device that converts DC power supplied from a DC power source into AC power and supplies the AC power to a load,
a DC/DC converter that boosts the DC power and outputs boosted DC power;
a film capacitor according to claim 1 or 2, which smoothes the boosted DC power and outputs at least two-phase DC power;
an inverter that generates the at least two-phase AC power based on the at least two-phase DC power;
A power conversion device comprising:

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