JP2008270331A - Film capacitor - Google Patents

Abstract

An object is to provide a highly reliable film capacitor in which a plurality of capacitor elements are connected in series.
Two dielectric films 11 and 12 each having a plurality of electrode layers insulated in the length direction are overlapped and wound, and one dielectric film 11 is In a film capacitor in which a plurality of capacitor elements are connected in series with the electrode layers 13a, 13b, and 13c facing the electrode layers 14a and 14b of the other dielectric film 12, a capacitor element in the vicinity of the center portion is formed. The width of each electrode layer and each non-metal part is set so that the electrode widths B and C are wider than the electrode widths A and D constituting the capacitor element on the outer side in the width direction. By increasing the capacitance and lowering the shared voltage, the heat generation of the capacitor element near the center is suppressed and the reliability is improved.
[Selection] Figure 1

Description

  The present invention relates to a film capacitor for high withstand voltage.

  In order to improve the withstand voltage of the film capacitor, a so-called series capacitor having a circuit configuration in which a plurality of capacitor elements are connected in series inside the capacitor element is used.

  As an example of the series capacitor, a sectional view thereof is shown in FIG. 5, and an equivalent circuit diagram thereof is shown in FIG.

  In the series capacitor of FIG. 5, a plurality of electrode layers 52a, 52b, 52c,... Electrically separated from each other along the length direction are arranged on one side of a strip-shaped dielectric film 51, and another strip-shaped dielectric material is arranged. A plurality of electrode layers 54 a, 54 b,... Are similarly arranged on one side of the film 53.

  Further, the dielectric films 51 and 53 are arranged and wound in a roll shape so that the electrode layer 54a partially overlaps the electrode layers 52a and 52b adjacent to each other with the dielectric film 51 interposed therebetween to form a film capacitor element. To do.

  Then, lead terminals (not shown) are led out from the wound electrode layers at the central end and the outer peripheral end to form a film capacitor.

  With such a configuration, capacitor elements 65a, 65b, 65c,... Are formed between the electrode layers 52a and 54a, 54b and 52b,. The

  Further, since the dielectric films 51 and 53 are wound, the dielectric film 51 is positioned under the dielectric film 53.

  Similarly, capacitor elements 66a, 66b, 66C,... Are formed between the electrode layers 52a and 54a, 54b and 52b,.

  In terms of equivalent circuit, two capacitor elements 65a and 66a, 65b and 66b,... With different dielectric films in the same electrode set are connected in parallel, and a plurality of capacitor elements with different electrode sets are connected in series. It becomes composition.

  Thus, when the capacitor elements are connected in series, a low voltage obtained by dividing the voltage between the lead terminals is applied to each capacitor element, so that the withstand voltage is increased.

For example, Patent Document 1 is known as prior art document information relating to the invention of the present application.
JP 2000-353637 A

  In the series capacitor as described above, each capacitor element is arranged in the width direction of the capacitor element and connected in series.

  For this reason, when a voltage is applied to the capacitor element, the capacitor elements such as 65a and 66a on the outer side in the width direction of the capacitor element can radiate heat from the side surface of the capacitor element. Capacitor elements such as 65b and 66b located inside are surrounded by the dielectric films 51 and 53 having low thermal conductivity, so that it is difficult to dissipate heat. As a result, the heat generation temperature is higher than that of the outer capacitor elements 65a and 66a. Becomes higher.

  A capacitor element having a high heat generation temperature is more likely to deteriorate than a capacitor element having a low heat generation temperature, and therefore, the capacitor element near the central portion, which is likely to deteriorate, may trigger a failure of the entire capacitor element.

  As described above, the failure of the capacitor element leads to the problem of lowering the reliability of the capacitor element, and therefore, a design that avoids such a problem as much as possible has been performed.

  Therefore, an object of the present invention is to provide a highly reliable film capacitor by reducing the heat generation temperature of the capacitor element near the center in the width direction of the capacitor element.

  In order to achieve this object, the film capacitor of the present invention is obtained by winding or laminating a metallized film on which a plurality of electrode layers insulated in the longitudinal direction are deposited on the surface of a long dielectric film. In the film capacitor in which a plurality of capacitor elements are connected in series, the electrode width constituting the capacitor element in the vicinity of the central portion in the width direction of the dielectric film is wider than the electrode width constituting the capacitor element on the outer side in the width direction. The film capacitor is characterized.

  By increasing the capacitance of the electrode that makes up the capacitor element near the center in the width direction, where heat dissipation is difficult, the voltage (shared voltage) applied to this capacitor element is reduced, so the heat generation temperature can be suppressed. As a result, deterioration of the capacitor element near the center of the capacitor element is prevented, and a highly reliable capacitor can be obtained.

  Hereinafter, the film capacitor of the present invention will be described with reference to one embodiment and the drawings.

(Embodiment 1)
FIG. 1 is a partial sectional view of a film capacitor according to the present embodiment, and FIG. 2 is a developed perspective view thereof.

  FIG. 3 is a partial cross-sectional view showing another example of the present embodiment when a double-sided vapor deposited metallized film is used, and FIG. 4 is an equivalent circuit diagram of the film capacitor shown in FIG.

  As shown in FIGS. 1 and 2, the dielectric film 11 is formed with one electrode layer 13a, 13b, 13c insulated in the length direction, and the dielectric film 12 has the other electrode layer 14a, 14b is formed.

  These electrode layers are provided in a continuous state in the length direction of the dielectric film.

  And between the electrode layers 13a and 13b of the dielectric film 11, and between the electrode layers 13b and 13c, a non-metal part 15 having no electrode layer continuous in the length direction is provided, and each electrode layer is insulated from each other. ing.

  Similarly, a non-metal part 16 is provided at the end of the dielectric film 12 so as not to contact the electrode lead-out part 18, and a non-metal part 17 is also provided between the electrode layers 14a and 14b.

  Then, by overlapping and winding the dielectric films 11 and 12, one of the electrode layers 13a to 13c is disposed so as to face the other electrode layers 14a and 14b with the dielectric film 11 therebetween. A plurality of capacitor elements each having the dielectric film 11 as a dielectric are connected in series to a portion where the electrode layers face each other.

  The part where this electrode layer faces across the dielectric film is the part that determines the capacitance of the capacitor element, but the electrode layer is provided continuously in the length direction of the dielectric film, Capacitance is determined.

  For this reason, the width of the portion where the electrode layers face each other across the dielectric film is hereinafter referred to as the electrode width.

  A capacitor element having the electrode width indicated by A in FIG. 1 facing the electrode layers 13a and 14a, that is, a capacitor element 41a shown in the equivalent circuit diagram of FIG. 4 is formed, and indicated by B facing the electrode layers 14a and 13b. The capacitor element having the electrode width, that is, the capacitor element 41b shown in the equivalent circuit diagram of FIG. 4 is formed.

  Similarly, a capacitor element 41c having an electrode width indicated by C facing the electrode layers 13b and 14b and a capacitor element 41d having an electrode width indicated by D facing the electrode layers 14b and 13c are formed.

  Further, since the dielectric films 11 and 12 are wound, the dielectric films 11 and 12 are alternately overlapped, and the dielectric films 11 are above and below the dielectric film 12.

  Capacitor elements 41a, 41b, 41c and 41d are formed between the dielectric film 11 and the dielectric film 11 on the dielectric film 12, and similarly, the dielectric film 12 and the dielectric film 11 located below the dielectric film 12 are formed. Capacitor elements 42a, 42b, 42c, and 42d are formed between the two.

  In the equivalent circuit diagram of FIG. 4, these capacitor elements have a configuration in which a plurality of capacitor elements having different electrode sets are connected in series, for example, 41a and 42a.

  In the present embodiment, the electrode widths indicated by B and C facing the electrode layers 13b and 14a, and 13b and 14b are set to the electrode layers 13a and 14a, depending on the setting of the electrode area and the nonmetal part of each electrode layer. The electrode layers 14b and 13c are configured to be wider than the electrode widths indicated by A and D facing each other.

  With this configuration, the capacitance of the capacitor elements 41b, 41c, 42b, and 42c near the center formed between the electrode layers 13b and 14a and between the electrode layers 13b and 14b is reduced between the electrode layers 13a and 14a and between the electrode layers 13b and 14c. It becomes larger than the capacitance of the outer capacitor elements 41a, 42a, 41d, and 42d near the both ends to be formed.

  As a result, the shared voltage applied to the capacitor elements 41b, 41c, 42b, and 42c near the center is lower than the shared voltage applied to the outer capacitor elements 41a, 42a, 41d, and 42d.

  For example, when the capacitance of the capacitor element 41b near the center is doubled that of the outer capacitor element 41a, the shared voltage applied to the capacitor element 41b near the center is half of the shared voltage applied to the outer capacitor element 41a. become.

  Thus, since heat generation can be suppressed by lowering the shared voltage of the capacitor elements 41b, 41c, 42b, and 42c in the vicinity of the center portion, deterioration can be suppressed.

  Further, by making the capacitor elements 41b, 41c, 42b, and 42c near the central portion that is a trigger for deterioration difficult to deteriorate, the reliability of the entire series capacitor can be improved.

Example 1
As shown in FIGS. 1 and 2, aluminum is deposited on one side of a polypropylene film 11 having a thickness of 6 μm as a dielectric film to form electrode layers 13a, 13b, and 13c continuous in the length direction of the dielectric film 11. Similarly, electrode layers 14a and 14b are formed on one side of a polypropylene film 12 having a thickness of 6 μm to obtain two types of metallized films.

  This metallized film is wound so that the electrode layers 13a and 14a, 14a and 13b, 13b and 14b, and 14b and 13c are opposed to each other with the polypropylene film 11 therebetween, and an electrode lead-out portion 15 is provided on both end faces to form a film capacitor. And

  Here, the width of the electrode layers 13a and 13c of the dielectric film 11 was 10 mm, the width of 13b was 30 mm, and the width of the electrode layers 14a and 14b of the dielectric film 12 was 23 mm.

  Further, the width of the non-metal part 15 and the non-metal part 16 was 5 mm, and the width of the non-metal part 17 was 4 mm.

  With this configuration, the electrode widths of the capacitor elements sandwiched between the opposing electrode layers are 5 mm for the electrode widths A and D of the outer capacitor elements 41a, 42a, 41d, and 42d, The electrode widths B and C of 42b, 41c and 42c are 13 mm.

(Example 2)
In Example 1, the widths of the electrode layers 13a and 13c of the dielectric film 11 were 11 mm, the width of 13b was 28 mm, and the electrode widths of the electrode layers 14a and 14b of the dielectric film 12 were 21 mm.

  Further, the width of the nonmetal part 15 and the nonmetal part 16 was 5 mm, and the width of the nonmetal part 17 was 8 mm.

  As the electrode width of each capacitor element in Example 2, the electrode widths A and D of the outer capacitor elements 41a, 42a, 41d and 42d are 6 mm, and the electrodes of the capacitor elements 41b, 42b, 41c and 42c near the center portion The widths B and C are 10 mm.

(Example 3)
In Example 1, the width of the electrode layers 13a and 13c of the dielectric film 11 was 12 mm, the width of 13b was 26 mm, and the width of the electrode layers 14a and 14b of the dielectric film 12 was 20 mm.

  Further, the width of the non-metal part 15 and the non-metal part 16 was 5 mm, and the width of the non-metal part 17 was 10 mm.

  As the effective electrode width of each capacitor element in the third embodiment, the electrode widths A and D of the outer capacitor elements 41a, 42a, 41d, and 42d are 7 mm, and the capacitor elements 41b, 42b, 41c, and 42c in the vicinity of the center portion. The electrode widths B and C are 8 mm.

(Comparative Example 1)
The width of the electrode layers 13a and 13c of the dielectric film 11 was 13 mm, the width of 13b was 24 mm, and the width of the electrode layers 14a and 14b of the dielectric film 12 was 21 mm.

  Further, the width of the nonmetal part 15 and the nonmetal part 16 was 5 mm, and the width of the nonmetal part 17 was 8 mm.

  The electrode widths A, B, C, and D of each capacitor element in the comparative example are all 8 mm.

  For each of the 20 film capacitors of Examples 1 to 3 and Comparative Example 1, the number of failures when a current of 5 A to 30 A was passed for 1000 hours was counted.

  These prototype film capacitors have a rated current of 5A, and it is desired that no failure occurs up to 10A, which is twice that of the rated current.

  The results are shown in (Table 1).

  From the results of (Table 1), it can be seen that in Examples 1 to 3 of this embodiment, even when 10 A is continuously applied, the number of failures is 0 and a highly reliable film capacitor is obtained.

  Further, comparing Examples 1 to 3, it can be seen that the wider electrode width for forming the capacitor elements 41b, 41c, 42b, and 42c near the center has a smaller number of failures even at a large current, and can withstand a larger current. .

  In the present embodiment, the example in which the electrode layers are formed on the different dielectric films 11 and 12 as shown in FIG. 1 is shown, but the present invention is not limited to this, and the dielectric film 31 is shown in FIG. The same effect can be obtained even when a film capacitor is constituted by a double-sided vapor-deposited metallized film provided with electrode layers on both sides and a dielectric film 32 provided with no electrode layer.

  In the configuration of FIG. 3, one electrode layer 33a, 33b, 33c is formed on one surface of the dielectric film 31, and the other electrode layer 34a, 34b is formed on the opposite surface of the same dielectric film 31, Similar to FIG. 1, capacitor elements similar to those in FIG. 4 are formed between the electrode layers 33a and 34a, between 34a and 33b, between 33b and 34b, and between 34b and 33c.

  Also in the case of FIG. 3, the widths of the electrode layers 33a, 33b, 33c, 34a, and 34b and the widths of the non-metal portions 35, 36, and 37 are adjusted so that the electrode width constituting the capacitor element near the center portion is set. By making the width of the electrode constituting the outer capacitor element wider, the capacitance of the capacitor element near the center is increased to reduce its shared voltage and to obtain a highly reliable film capacitor by suppressing heat generation. Can do.

  In the film capacitor of the present invention, the electrode width for forming the capacitor element near the center is wider than the electrode width for forming the outer capacitor element. Reduced. As a result, the deterioration of the capacitor element in the vicinity of the central portion can be reduced, the reliability of the film capacitor can be improved, it can be used for a larger current, and it is useful for a film capacitor for a high withstand voltage.

1 is a partial cross-sectional view of a single-sided metallized film capacitor according to an embodiment of the present invention. Deployed perspective view of the single-side vapor deposition type metallized film capacitor Partial sectional view of the double-sided metallized film capacitor Equivalent circuit diagram of the same metallized film capacitor Partial sectional view of a conventional single-sided metallized film capacitor Equivalent circuit diagram of conventional metalized film capacitor

Explanation of symbols

11, 12 Dielectric film 13a, 13b, 13c Electrode layer 14a, 14b Electrode layer 15, 16, 17 Non-metal part 18 Electrode extraction part 31, 32 Dielectric film 33a, 33b, 33c Electrode layer 34a, 34b Electrode layer 35, 36, 37 Non-metal parts 41a, 42a, 41d, 42d Outer capacitor elements 41b, 42b, 41c, 42c Capacitor elements near the center 51, 53 Dielectric films 52a, 52b, 52c Electrode layers 54a, 54b Electrode layers 65a, 65b, 65c capacitor element 66a, 66b, 66c capacitor element

Claims (1)

In a film capacitor in which a plurality of capacitor elements are connected in series by winding or laminating a metallized film on which a plurality of electrode layers insulated in the longitudinal direction are wound on the surface of a long dielectric film, A film capacitor characterized in that the electrode width constituting the capacitor element near the center in the width direction of the body film is wider than the electrode width constituting the capacitor element on the outer side in the width direction.

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