DESCRIPTION
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
CAPACITOR UNIT AND ELECTRONIC DEVICE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Title of Invention
CAPACITOR UNIT AND ELECTRONIC DEVICE
5 Technical Field
[0001] The present disclosure relates to a capacitor unit and an electronic device.
Background Art
[0002] Electronic devices such as power conversion apparatuses that convert input
power and supply the power resulting from the conversion to a load may include a
10 capacitor unit with a large capacitance. Patent Literature 1 describes an example of such
an electronic device. A vehicle drive controller described in Patent Literature 1 includes
a capacitor unit for smoothing power installed in the center of a housing.
Citation List
Patent Literature
15 [0003] Patent Literature 1: Unexamined Japanese Patent Application Publication
No. 2013-163503
Summary of Invention
Technical Problem
[0004] Heat generated in the capacitor unit during energization is dissipated to air
20 inside the housing of the electronic device. The housing for the electronic device
accommodates heating elements such as switching elements, in addition to the capacitor
unit, which may increase the temperature of the air inside the housing. The capacitor
unit with a large capacitance generates a large amount of heat, and thus may not be
cooled sufficiently due to the rising temperature in the housing. This may increase the
25 internal temperature of the capacitor unit, or more specifically, the temperature of
capacitor elements in the capacitor unit.
[0005] For a capacitor element being a film capacitor, the film for the capacitor
3
element is to have an allowable temperature higher than the maximum temperature
reachable by the capacitor element. The temperature of the capacitor element rises as a
larger amount of current flows through the capacitor element. This may limit the
amount of current flowing through the capacitor elements when the allowable
5 temperature of the film is not sufficiently high. In other words, the capacitor unit may
have design limitations, including the allowable temperature of the film in the capacitor
elements and the current flowing through the capacitor elements, due to a temperature
increase in the capacitor elements accommodated in the housing. This is not limited to
power supply devices including a capacitor unit with a large capacitance, but may occur
10 to any electronic devices including a capacitor unit that may fail to cool the capacitor unit
sufficiently.
[0006] In response to the above circumstances, an objective of the present
disclosure is to provide a capacitor unit and an electronic device including the capacitor
unit with a smaller temperature increase in capacitor elements.
15 Solution to Problem
[0007] To achieve the above objective, a capacitor unit according to an aspect of
the present disclosure includes a plurality of capacitor elements and one or more heat
transfer members. The one or more heat transfer members are located adjacent to at
least one capacitor element of the plurality of capacitor elements. The one or more heat
20 transfer members internally dissipate heat received from at least one capacitor element of
the plurality of capacitor elements.
Advantageous Effects of Invention
[0008] The capacitor unit according to the above aspect of the present disclosure
allows heat generated in the plurality of capacitor elements to be dispersed inside the heat
25 transfer members. The capacitor elements are thus cooled, which results in a smaller
temperature increase.
Brief Description of Drawings
4
[0009] FIG. 1 is a block diagram of an electronic device according to an
embodiment;
FIG. 2 is a front view of a capacitor unit according to the embodiment;
FIG. 3 is a cross-sectional view of the capacitor unit according to the embodiment
5 taken along line III-III as viewed in the direction indicated by the arrows in FIG. 2;
FIG. 4 is a diagram of a capacitor element in the embodiment;
FIG. 5 is a cross-sectional view of the capacitor unit according to the embodiment;
FIG. 6 is a rear view of the capacitor unit according to the embodiment;
FIG. 7 is a cross-sectional view of the electronic device according to the
10 embodiment;
FIG. 8 is a front view of a capacitor unit according to a first modification of the
embodiment;
FIG. 9 is a top view of a capacitor unit according to a second modification of the
embodiment; and
15 FIG. 10 is a cross-sectional view of an electronic device according to a
modification of the embodiment.
Description of Embodiments
[0010] A capacitor unit and an electronic device according to one or more
embodiments of the present disclosure are described below in detail with reference to the
20 drawings. In the figures, the same reference signs denote the same or equivalent
components.
[0011] Examples of the electronic device include a power conversion apparatus
mounted on a railway vehicle that converts direct current (DC) power supplied from a
DC power source to three-phase alternating current (AC) power and supplies the AC
25 power to an electric motor. An electronic device 1 according to Embodiment 1 is
described below using the power conversion apparatus as an example.
[0012] The electronic device 1 illustrated in FIG. 1 receives DC power from an
5
unillustrated power source, or more specifically, from a current collector that acquires
power supplied from a substation through a power supply line. The power supply line
is, for example, an overhead line or a third rail. The current collector is, for example, a
pantograph or a collector shoe. The electronic device 1 converts the DC power supplied
5 from the current collector to three-phase AC power and supplies the three-phase AC
power resulting from the conversion to a load 51. In the embodiment, the electronic
device 1 is a three-level inverter, and the load 51 is a three-phase induction motor.
[0013] The electronic device 1 includes a positive terminal 1a that is connected to
the current collector, a negative terminal 1b that is grounded, a capacitor unit 11 that is
10 charged with power supplied from the current collector, and a power converter 12 that
converts DC power supplied from the current collector through the capacitor unit 11 to
three-phase AC power. Preferably, the positive terminal 1a is electrically connected to
the current collector with, for example, a contactor or a filter reactor. The capacitor unit
11 includes a first capacitor C1 and a second capacitor C2. The first capacitor C1 and
15 the second capacitor C2 are connected in series to each other.
[0014] The power converter 12 includes a pair of primary terminals electrically
connected to the positive terminal 1a and the negative terminal 1b. A terminal between
the pair of primary terminals is connected to a connection point between the first
capacitor C1 and the second capacitor C2 that are connected in series to each other. The
20 power converter 12 includes three secondary terminals corresponding to phases U, V, and
W of the three-phase AC power and connected to the corresponding input terminals of
the load 51. The power converter 12 includes multiple switching elements controlled by
an unillustrated controller. The switching elements are, for example, insulated-gate
bipolar transistors (IGBTs). The power converter 12 converts power through a
25 switching operation controlled by the controller that switches the switching elements
between on and off. More specifically, the power converter 12 converts the DC power
supplied through the primary terminals to three-phase AC power to be supplied to the
6
load 51 and outputs the three-phase AC power through the secondary terminals.
[0015] The capacitor unit 11 with a smaller internal temperature increase is
described below. As illustrated in FIG. 2 and FIG. 3 that is a cross-sectional view taken
along line III-III in FIG. 2, the capacitor unit 11 includes multiple capacitor elements 21a,
5 21b, 21c, 21d, 31a, 31b, 31c, and 31d, and heat transfer members 22a, 22b, 22c, 32a, 32b,
and 32c that internally disperse heat received from the capacitor elements 21a, 21b, 21c,
21d, 31a, 31b, 31c, and 31d. The internal temperature of the capacitor unit 11 refers,
more specifically, to the temperature of each of the capacitor elements 21a, 21b, 21c, 21d,
31a, 31b, 31c, and 31d. In FIGS. 2 and 3, Z-axis is a vertical direction, and Y-axis
10 extends parallel to main surfaces of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b,
31c, and 31d. X-axis is orthogonal to Y- and Z-axes.
[0016] The capacitor unit 11 further includes a first busbar 23a electrically
connected to the positive electrodes of the capacitor elements 21a, 21b, 21c, and 21d, and
a first busbar 33a electrically connected to the positive electrodes of the capacitor
15 elements 31a, 31b, 31c, and 31d. The first busbars 23a and 33a are plates of a
conducting material, such as copper or aluminum.
[0017] The capacitor unit 11 further includes a second busbar 23b electrically
connected to the negative electrodes of the capacitor elements 21a, 21b, 21c, and 21d,
and a second busbar 33b electrically connected to the negative electrodes of the capacitor
20 elements 31a, 31b, 31c, and 31d. The second busbars 23b and 33b are plates of a
conducting material, such as copper or aluminum. The capacitor unit 11 further
includes a first terminal 24a electrically connected to the first busbar 23a, a first terminal
34a electrically connected to the first busbar 33a, a second terminal 24b electrically
connected to the second busbar 23b, and a second terminal 34b electrically connected to
25 the second busbar 33b.
[0018] The capacitor unit 11 further includes an insulating member 25 that at least
partially covers the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, and the
7
heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c.
[0019] The components of the capacitor unit 11 are described in detail below. As
illustrated in FIG. 2, the capacitor elements 21a, 21b, 21c, and 21d are arranged in a row
with the main surfaces facing one another. More specifically, the capacitor elements
5 21a, 21b, 21c, and 21d are arranged in X-direction with the main surfaces facing
orthogonally to X-axis. Similarly, the capacitor elements 31a, 31b, 31c, and 31d are
arranged in a row with the main surfaces facing one another. More specifically, the
capacitor elements 31a, 31b, 31c, and 31d are arranged in X-direction with the main
surfaces facing in the direction orthogonal to the X-axis.
10 [0020] The capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d have the
same structure. The structure of the capacitor element 21a is thus described with
reference to FIG. 4.
The capacitor element 21a is a film capacitor including a film 41c on which a
positive electrode 41a is located and a film 41d on which a negative electrode 41b is
15 located. The films 41c and 41d overlap with each other and are wound around the
central axis to form the capacitor element 21a. The film 41c is a plastic film on which a
metal, such as aluminum or zinc, is vapor-deposited to form the positive electrode 41a.
Similarly, the film 41d is a plastic film on which a metal, such as aluminum or zinc, is
vapor-deposited to form the negative electrode 41b.
20 [0021] The capacitor element 21a has one end as a positive terminal and the other
end as a negative terminal in the direction along the central axis of the capacitor element
21a. In the example of FIG. 4, the capacitor element 21a has the upper end as the
positive terminal and the lower end as the negative terminal. In the examples of FIGS. 2
and 3, the capacitor element 21a has the upper end in Z-direction as the positive terminal
25 of the capacitor element 21a and the lower end in Z-direction as the negative terminal of
the capacitor element 21a.
[0022] The heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c are each located
8
adjacent to at least one of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and
31d to internally disperse heat transferred from at least one of the capacitor elements 21a,
21b, 21c, 21d, 31a, 31b, 31c, and 31d.
[0023] The heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c are each
5 preferably located between two of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b,
31c, and 31d that are adjacent to each other. Also, the heat transfer members 22a, 22b,
22c, 32a, 32b, and 32c are each preferably located adjacent to a different one of the
capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d.
[0024] In the embodiment, the heat transfer members 22a, 22b, 22c, 32a, 32b, and
10 32c are located between two of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c,
and 31d that are adjacent to each other at different positions. More specifically, the heat
transfer member 22a is located between the capacitor elements 21a and 21b to internally
disperse heat received from the capacitor elements 21a and 21b. The heat transfer
member 22b is located between the capacitor elements 21b and 21c to internally disperse
15 heat received from the capacitor elements 21b and 21c. The heat transfer member 22c
is located between the capacitor elements 21c and 21d to internally disperse heat received
from the capacitor elements 21c and 21d.
[0025] Similarly, the heat transfer member 32a is located between the capacitor
elements 31a and 31b to internally disperse heat received from the capacitor elements 31a
20 and 31b. The heat transfer member 32b is located between the capacitor elements 31b
and 31c to internally disperse heat received from the capacitor elements 31b and 31c.
The heat transfer member 32c is located between the capacitor elements 31c and 31d to
internally disperse heat received from the capacitor elements 31c and 31d.
[0026] The heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c are each
25 preferably a plate with at least one main surface in contact with at least one of the
capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d. Being in contact herein
includes direct contact and indirect contact. In the embodiment, the heat transfer
9
member 22a is a plate with one main surface in contact with the capacitor element 21a
and the other main surface in contact with the capacitor element 21b. The heat transfer
member 22b is a plate with one main surface in contact with the capacitor element 21b
and the other main surface in contact with the capacitor element 21c. The heat transfer
5 member 22c is a plate with one main surface in contact with the capacitor element 21c
and the other main surface in contact with the capacitor element 21d.
[0027] Similarly, the heat transfer member 32a is a plate with one main surface in
contact with the capacitor element 31a and the other main surface in contact with the
capacitor element 31b. The heat transfer member 32b is a plate with one main surface
10 in contact with the capacitor element 31b, and the other main surface in contact with the
capacitor element 31c. The heat transfer member 32c is a plate with one main surface in
contact with the capacitor element 31c and the other main surface in contact with the
capacitor element 31d.
[0028] The heat transfer member 22a being a plate in contact with the capacitor
15 elements 21a and 21b allows heat to be transferred from the capacitor elements 21a and
21b to the heat transfer member 22a more efficiently and the capacitor elements 21a and
21b to be cooled more efficiently. The same applies to the heat transfer members 22b,
22c, 32a, 32b, and 32c. The capacitor unit 11 thus has a smaller internal temperature
increase.
20 [0029] The heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c may be formed
from a highly thermally conductive material, or for example, a metal such as copper or
aluminum.
[0030] As described above, the heat transfer members 22a, 22b, 22c, 32a, 32b, and
32c allow heat generated in the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and
25 31d to be transferred to the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c and
dispersed inside the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c. The heat
transfer members 22a, 22b, 22c, 32a, 32b, and 32c further increase the efficiency of heat
10
transfer from the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d to the
outer surface of the capacitor unit 11, thus reducing the temperature difference between
the outer surface of the capacitor unit 11 and the capacitor elements 21a, 21b, 21c, 21d,
31a, 31b, 31c, and 31d. The capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and
5 31d thus have a smaller internal temperature increase, whereas the outer surface of the
capacitor unit 11 has a temperature increase.
[0031] The heat dispersed inside the heat transfer members 22a, 22b, 22c, 32a, 32b,
and 32c as described above also causes the capacitor elements 21a, 21b, 21c, 21d, 31a,
31b, 31c, and 31d to have less temperature variations. In other words, the maximum
10 temperature of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d is lower.
[0032] The first busbar 23a in contact with the vertically upper ends of the capacitor
elements 21a, 21b, 21c, and 21d is electrically connected to the positive electrodes 41a of
the capacitor elements 21a, 21b, 21c, and 21d. Similarly, the first busbar 33a in contact
with the vertically upper ends of the capacitor elements 31a, 31b, 31c, and 31d is
15 electrically connected to the positive electrodes 41a of the capacitor elements 31a, 31b,
31c, and 31d.
[0033] The second busbar 23b in contact with the vertically lower ends of the
capacitor elements 21a, 21b, 21c, and 21d is electrically connected to the negative
electrodes 41b of the capacitor elements 21a, 21b, 21c, and 21d. Similarly, the second
20 busbar 33b in contact with the vertically lower ends of the capacitor elements 31a, 31b,
31c, and 31d is electrically connected to the negative electrodes 41b of the capacitor
elements 31a, 31b, 31c, and 31d.
[0034] The first terminal 24a is attached to the first busbar 23a with an unillustrated
fastener while being in contact with the first busbar 23a. This electrically connects the
25 first terminal 24a to the first busbar 23a. The first terminal 34a is attached to the first
busbar 33a with an unillustrated fastener while being in contact with the first busbar 33a.
This electrically connects the first terminal 34a to the first busbar 33a.
11
[0035] Similarly, the second terminal 24b is attached to the second busbar 23b with
an unillustrated fastener while being in contact with the second busbar 23b. This
electrically connects the second terminal 24b to the second busbar 23b. The second
terminal 34b is attached to the second busbar 33b with an unillustrated fastener while
5 being in contact with the second busbar 33b. This electrically connects the second
terminal 34b to the second busbar 33b.
[0036] The capacitor elements 21a, 21b, 21c, and 21d, the first busbar 23a, the
second busbar 23b, the first terminal 24a, and the second terminal 24b described above
are included in the first capacitor C1. The first terminal 24a serves as a positive terminal
10 of the first capacitor C1. The second terminal 24b serves as a negative terminal of the
first capacitor C1. The first terminal 24a is electrically connected to the positive
terminal 1a and the power converter 12 with an unillustrated busbar. The second
terminal 24b is electrically connected to the power converter 12 and the second capacitor
C2 with an unillustrated busbar.
15 [0037] The capacitor elements 31a, 31b, 31c, and 31d, the first busbar 33a, the
second busbar 33b, the first terminal 34a, and the second terminal 34b described above
are included in the second capacitor C2. The first terminal 34a serves as a positive
terminal of the second capacitor C2. The second terminal 34b serves as a negative
terminal of the second capacitor C2. The first terminal 34a is electrically connected to
20 the power converter 12 and the first capacitor C1 with an unillustrated busbar. The
second terminal 34b is electrically connected to the negative terminal 1b and the power
converter 12 with an unillustrated busbar.
[0038] The insulating member 25 is formed from a resin, such as epoxy, urethane,
or silicone. The insulating member 25 insulates the capacitor elements 21a, 21b, 21c,
25 21d, 31a, 31b, 31c, and 31d, and the heat transfer members 22a, 22b, 22c, 32a, 32b, and
32c from one another. In the embodiment, the insulating member 25 at least partially
covers the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, and the heat
12
transfer members 22a, 22b, 22c, 32a, 32b, and 32c. In other words, the capacitor
elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, and the heat transfer members 22a,
22b, 22c, 32a, 32b, and 32c are at least partially encapsulated by the insulating member
25. This fixes the positions of the heat transfer members 22a, 22b, 22c, 32a, 32b, and
5 32c relative to the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d.
[0039] In the embodiment, the insulating member 25 covers the first busbars 23a
and 33a and the second busbars 23b and 33b, and covers the first terminals 24a and 34a
and the second terminals 24b and 34b, with the first terminals 24a and 34a and the second
terminals 24b and 34b being partially exposed. This fixes the positions of the capacitor
10 elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, the heat transfer members 22a, 22b,
22c, 32a, 32b, and 32c, the first busbars 23a and 33a, the second busbars 23b and 33b, the
first terminals 24a and 34a, and the second terminals 24b and 34b relative to one another.
With the first terminals 24a and 34a and the second terminals 24b and 34b being partially
exposed, the busbars can be electrically connected to the first terminals 24a and 34a and
15 the second terminals 24b and 34b.
[0040] To form the insulating member 25 covering the components of the capacitor
unit 11 as described above, for example, an unillustrated case accommodating the
components of the capacitor unit 11 is filled with an epoxy resin, and the cured resin is
removed from the case.
20 [0041] To increase cooling performance, as illustrated in FIG. 5, preferably, the
capacitor unit 11 is thermally connected to the heat transfer members 22a, 22b, 22c, 32a,
32b, and 32c, and further includes a cooler 26 that dissipates heat transferred from the
capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d through the heat transfer
members 22a, 22b, 22c, 32a, 32b, and 32c. FIG. 5 is a cross-sectional view of the
25 capacitor unit 11 taken along the same line as in FIG. 3.
[0042] The cooler 26 includes a heat-receiving block 27 that is thermally connected
to the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c, and a heat dissipater 28
13
that dissipates heat transferred from the heat-receiving block 27. The insulating
member 25 is attached to one main surface 27a of the heat-receiving block 27. The heat
dissipater 28 is attached to the other main surface 27b of the heat-receiving block 27.
The heat-receiving block 27 thermally connected to the heat transfer members 22a, 22b,
5 22c, 32a, 32b, and 32c allows heat to be transferred from the capacitor elements 21a, 21b,
21c, 21d, 31a, 31b, 31c, and 31d to the heat-receiving block 27 through the heat transfer
members 22a, 22b, 22c, 32a, 32b, and 32c. The heat-receiving block 27 is preferably
formed from a highly thermally conductive material, or for example, a metal such as
copper or aluminum.
10 [0043] The heat-receiving block 27 is preferably in contact with the heat transfer
members 22a, 22b, 22c, 32a, 32b, and 32c. In the embodiment, the insulating member
25 covers the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c, with the end faces
of the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c closer to the cooler 26
being exposed. The insulating member 25 is attached to the cooler 26 with the end
15 faces of the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c in direct contact with
the cooler 26. The insulating member 25 is attached to the heat-receiving block 27 in
the cooler 26 with, for example, an unillustrated fastener.
[0044] The heat-receiving block 27 in contact with the end faces of the heat transfer
members 22a, 22b, 22c, 32a, 32b, and 32c allows heat to be transferred from the heat
20 transfer members 22a, 22b, 22c, 32a, 32b, and 32c directly to the heat-receiving block 27,
thus increasing heat transfer efficiency. This allows the capacitor elements 21a, 21b,
21c, 21d, 31a, 31b, 31c, and 31d to be cooled more efficiently. The capacitor elements
21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d can thus have a smaller temperature increase.
[0045] The heat dissipater 28 dissipates heat transferred from the heat-receiving
25 block 27 to ambient air. Heat transferred from the capacitor elements 21a, 21b, 21c,
21d, 31a, 31b, 31c, and 31d to the heat-receiving block 27 through the heat transfer
members 22a, 22b, 22c, 32a, 32b, and 32c is dissipated to ambient air by the heat
14
dissipater 28 to cool the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d.
In the embodiment, as illustrated in FIG. 6, the heat dissipater 28 includes multiple fins
having main surfaces parallel to a YZ plane. More specifically, the heat dissipater 28 is
preferably formed from a highly thermally conductive material, or for example, a metal
5 such as copper or aluminum.
[0046] As illustrated in FIG. 7, the electronic device 1 accommodates the capacitor
unit 11 with the above structure and the power converter 12 inside a housing. More
specifically, the electronic device 1 includes a housing 13 that accommodates the
capacitor unit 11 and the power converter 12, and a power converter cooler 14 that cools
10 the power converter 12. For ease of illustration, FIG. 7 illustrates, of the components of
the power converter 12, multiple switching elements SW alone, and does not illustrate the
other components of the power converter 12, such as the positive terminal 1a, the
negative terminal 1b, busbars connected to the positive terminal 1a and the negative
terminal 1b, and terminals and busbars connected to the load 51.
15 [0047] The components of the electronic device 1 are described in detail below.
The housing 13 has openings 13a and 13b. In the embodiment, the openings 13a and
13b are on different surfaces.
[0048] The capacitor unit 11 is accommodated in the housing 13. The cooler 26
in the capacitor unit 11 closes the opening 13a, with a portion of the cooler 26 being
20 exposed outside the housing 13 through the opening 13a. With the opening 13a closed
with a portion of the cooler 26, air outside the housing 13 containing dust, moisture, and
other foreign matter is less likely to flow into the housing 13 through the opening 13a.
More specifically, the heat-receiving block 27 closes the opening 13a from inside the
housing 13, with the heat dissipater 28 being exposed outside the housing 13. The heat
25 dissipater 28 being exposed outside the housing 13 thus dissipates heat transferred from
the heat-receiving block 27 to air outside the housing 13. The capacitor elements 21a,
21b, 21c, 21d, 31a, 31b, 31c, and 31d are thus cooled. The temperature of air outside
15
the housing 13 is lower than the temperature of the air inside the housing 13. The
capacitor unit 11 thus has higher cooling performance than a capacitor unit that dissipates
heat to air inside a housing.
[0049] The power converter cooler 14 includes a heat-receiving block 15 on which
5 the multiple switching elements SW are mounted and a heat dissipater 16 that dissipates
heat transferred from the switching elements SW through the heat-receiving block 15.
The switching elements SW are mounted on one main surface 15a of the heat-receiving
block 15, or more specifically, the surface facing the inside of the housing 13. The
power converter 12 includes, for example, six switching elements SW that are arranged
10 two-dimensionally on the main surface 15a of the heat-receiving block 15. The heat
dissipater 16 is mounted on the other main surface 15b of the heat-receiving block 15, or
more specifically, the surface facing the outside of the housing 13. The heat-receiving
block 15 is preferably formed from a highly thermally conductive material, or for
example, a metal such as copper or aluminum.
15 [0050] The power converter cooler 14 with the above structure is accommodated in
the housing 13 to close the opening 13b, with a portion of the power converter cooler 14
being exposed outside the housing 13 through the opening 13b. With the opening 13b
closed with a portion of the power converter cooler 14, air outside the housing 13
containing dust, moisture, and other foreign matter is less likely to flow into the housing
20 13 through the opening 13b. More specifically, the heat-receiving block 15 closes the
opening 13b from inside the housing 13, with the heat dissipater 16 being exposed
outside the housing 13. The heat dissipater 16 being exposed outside the housing 13
thus dissipates heat transferred from the switching elements SW through the heatreceiving block 15 to air outside the housing 13. The switching elements SW are thus
25 cooled.
[0051] The heat dissipater 16 includes multiple fins having main surfaces parallel to
an XY plane. The electronic device 1 mounted on a railway vehicle with Y-axis aligned
16
with the traveling direction of the railway vehicle causes air to flow between the fins on
the heat dissipater 16 as the vehicle travels. The switching elements SW are thus cooled
more efficiently.
[0052] A laminate busbar 17 electrically connects the capacitor unit 11 and the
5 power converter 12. More specifically, the laminate busbar 17 includes a stack of an
insulating layer and a conductive layer to electrically connect the first terminals 24a and
34a and the second terminals 24b and 34b to the corresponding switching elements SW.
The laminate busbar 17 is attached to the first terminals 24a and 34a, the second terminals
24b and 34b, and the switching elements SW with unillustrated fasteners.
10 [0053] When electric power is supplied to the electronic device 1 with the above
structure, or more specifically, when the electronic device 1 is electrically connected to
the current collector, a current flows into the capacitor elements 21a, 21b, 21c, 21d, 31a,
31b, 31c, and 31d, thus generating heat in the capacitor elements 21a, 21b, 21c, 21d, 31a,
31b, 31c, and 31d. The heat generated in the capacitor elements 21a, 21b, 21c, 21d,
15 31a, 31b, 31c, and 31d is transferred to the heat-receiving block 27 in the cooler 26
through the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c. The heat
transferred to the heat-receiving block 27 is dissipated to air outside the housing 13 either
through the heat dissipater 28 attached to the heat-receiving block 27 or through the
housing 13 in contact with the heat-receiving block 27. This cools the capacitor
20 elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, and the capacitor elements 21a, 21b,
21c, 21d, 31a, 31b, 31c, and 31d have a smaller temperature increase.
[0054] During the operation of the power converter 12, the switching elements SW
generate heat when being switched between on and off. The heat generated in the
switching elements SW is transferred to the heat-receiving block 15. The heat
25 transferred to the heat-receiving block 15 is dissipated from the heat dissipater 16 to air
outside the housing 13. The switching elements SW are thus cooled.
[0055] As described above, heat generated in the capacitor elements 21a, 21b, 21c,
17
21d, 31a, 31b, 31c, and 31d and in any one of the switching elements SW is dissipated to
air outside the housing 13. The air inside the housing 13 thus has a smaller temperature
increase. The capacitor unit 11 thus has a smaller internal temperature increase, and the
switching elements SW also have a smaller temperature increase.
5 [0056] In the capacitor unit 11 according to the embodiment, as described above,
heat generated in the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d is
transferred to the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c, and dispersed
inside the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c. This reduces the
temperature difference between the outer surface of the capacitor unit 11 and the
10 capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d. The capacitor elements
21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d thus have a smaller temperature increase.
[0057] The heat dispersed inside the heat transfer members 22a, 22b, 22c, 32a, 32b,
and 32c as described above also causes the capacitor elements 21a, 21b, 21c, 21d, 31a,
31b, 31c, and 31d to have less temperature variations. In other words, the maximum
15 temperature of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d is lower.
[0058] For the capacitor unit 11 including the cooler 26, heat generated in the
capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d is transferred to the cooler
26 through the heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c and dissipated
from the cooler 26. This cools the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c,
20 and 31d more efficiently, and the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c,
and 31d have a still smaller temperature increase.
[0059] The degree of degradation of the films 41c and 41d depends on the
temperature of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d and the
potential gradient in the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d.
25 More specifically, as the temperature or potential gradient increases in the capacitor
elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, the films 41c and 41d have a shorter
service life.
18
[0060] As described above, the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b,
31c, and 31d having a smaller temperature increase can have a longer service life. The
capacitor elements with substantially the same service life can have a higher potential
gradient. In other words, with substantially the same service life, a larger voltage can be
5 applied to the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d, or the films
41c and 41d can be thinner. In other words, the capacitor unit 11 can have increased
design freedom.
[0061] A larger voltage may be applied to the capacitor elements 21a, 21b, 21c,
21d, 31a, 31b, 31c, and 31d to increase the capacitance of the capacitor unit 11. The
10 films 41c and 41d that are thinner can reduce the size of the capacitor elements 21a, 21b,
21c, 21d, 31a, 31b, 31c, and 31d, or in other words, the size of the capacitor unit 11.
[0062] Embodiments of the present disclosure are not limited to the embodiments
described above.
The number of capacitor elements in the capacitor unit 11 is not limited to the
15 number of capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d in the above
example, but may be any number. In the embodiment, the capacitor unit 11 includes
two capacitor groups, or the first capacitor C1 and the second capacitor C2, but may
include any number of capacitor groups. For example, the capacitor unit may include
the first capacitor C1 alone, or may include a third capacitor in addition to the first
20 capacitor C1 and the second capacitor C2.
[0063] The structure of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c,
and 31d is not limited to the structure in the above example. In one example, the
capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d may be film capacitors of
metal foil.
25 [0064] The heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c may be in any
number and in any shape that allow heat generated in the capacitor elements 21a, 21b,
21c, 21d, 31a, 31b, 31c, and 31d to be dispersed internally. In one example, the
19
capacitor unit 11 may include a single flat plate heat transfer member. In another
example, the capacitor unit 11 may include rod-shaped heat transfer members 29a, 29b,
29c, 35a, 35b, and 35c, as illustrated in FIG. 8. The heat transfer members 29a, 29b,
29c, 35a, 35b, and 35c are each located adjacent to at least one of the capacitor elements
5 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d to internally disperse heat transferred from at
least one of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d. For the
capacitor unit 11 including the cooler 26, the heat transfer members 29a, 29b, 29c, 35a,
35b, and 35c transfer heat transferred from at least one of the capacitor elements 21a,
21b, 21c, 21d, 31a, 31b, 31c, and 31d to the cooler 26.
10 [0065] The heat transfer members 29a, 29b, 29c, 35a, 35b, and 35c are each
preferably located between two of the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b,
31c, and 31d that are adjacent to each other. Also, the heat transfer members 29a, 29b,
29c, 35a, 35b, and 35c are each preferably located adjacent to a different one of the
capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c, and 31d.
15 [0066] As illustrated in FIG. 8, the heat transfer members 29a, 29b, 29c, 35a, 35b,
and 35c are each preferably located between two of the capacitor elements 21a, 21b, 21c,
21d, 31a, 31b, 31c, and 31d that are adjacent to each other at different positions.
[0067] In another example, the heat transfer members 22a, 22b, 22c, 32a, 32b, and
32c may be U-bent plates or U-bent rods. In another example, the heat transfer
20 members 22a, 22b, 22c, 32a, 32b, and 32c may be plates including an internal channel
containing refrigerant. The same applies to the heat transfer members 29a, 29b, 29c,
35a, 35b, and 35c.
[0068] The heat transfer members 22a, 22b, 22c, 32a, 32b, 32c, 29a, 29b, 29c, 35a,
35b, and 35c may be located differently from the above example. In one example, in
25 addition to the positions described above, a heat transfer member may be located adjacent
to the capacitor element 21d alone, or specifically, adjacent to the surface of the capacitor
element 21d facing in the positive X-direction. In another example, a heat transfer
20
member may be located between the first busbar 23a and the surface of the capacitor
element 21a facing in the negative X-direction.
[0069] The heat transfer members 22a, 22b, 22c, 32a, 32b, 32c, 29a, 29b, 29c, 35a,
35b, and 35c may be entirely covered with the insulating member 25.
5 [0070] The heat transfer members 22a, 22b, 22c, 32a, 32b, 32c, 29a, 29b, 29c, 35a,
35b, and 35c may be in indirect contact with the cooler 26. In one example, a member
that reduces contact thermal resistance, such as a heat dissipating sheet, grease, or other
thermal interface material (TIM), may be located between the heat-receiving block 27 in
the cooler 26 and the heat transfer members 22a, 22b, 22c, 32a, 32b, 32c, 29a, 29b, 29c,
10 35a, 35b, and 35c.
[0071] The material of the heat transfer members 22a, 22b, 22c, 32a, 32b, 32c, 29a,
29b, 29c, 35a, 35b, and 35c is not limited to metals but may be any material that can
internally disperse heat. In one example, each of the heat transfer members 22a, 22b,
22c, 32a, 32b, 32c, 29a, 29b, 29c, 35a, 35b, and 35c may be an anisotropic heat
15 transferring member formed from, for example, graphite. In another example, each of
the heat transfer members 22a, 22b, 22c, 32a, 32b, 32c, 29a, 29b, 29c, 35a, 35b, and 35c
may be a member formed from multiple materials, such as a cladding material formed
from different metals.
[0072] The method for fixing the positions of the heat transfer members 22a, 22b,
20 22c, 32a, 32b, and 32c relative to the capacitor elements 21a, 21b, 21c, 21d, 31a, 31b,
31c, and 31d is not limited to encapsulation with the insulating member 25, but may be
any method. When the electronic device 1 is to be mounted on a railway vehicle, the
heat transfer members 22a, 22b, 22c, 32a, 32b, and 32c is preferably fixed with a method
that provides firm fixing to maintain the positions relative to the capacitor elements 21a,
25 21b, 21c, 21d, 31a, 31b, 31c, and 31d under vibrations from a traveling railway vehicle.
[0073] The cooler 26 may have any shape that can dissipate transferred heat. As
illustrated in FIG. 9, for example, portions of the heat transfer members 22a, 22b, and 22c
21
may extend through the heat-receiving block 27 to serve as heat dissipaters. Similarly,
portions of the heat transfer members 32a, 32b, and 32c may extend through the heatreceiving block 27 to serve as heat dissipaters. The cooler 26 illustrated in FIG. 9 may
further include a heat dissipater 28 similar to the heat dissipater in FIG. 5.
5 [0074] The heat dissipater 28 may have any shape that can dissipate heat transferred
from the heat-receiving block 27. In one example, the fins on the heat dissipater 28 may
be modified into any shape as appropriate for air flow around the heat dissipater 28. In
another example, the heat dissipater 28 may include multiple rod-shaped protrusions. In
another example, the heat dissipater 28 may include a heat pipe or a plate including an
10 internal channel containing refrigerant.
[0075] The cooler 26 may be located differently from the above example. More
specifically, the cooler 26 may be located inside the housing 13 rather than being outside
the housing 13. In this case, as illustrated in FIG. 10, the cooler 26 is preferably at a
position inside the housing 13 into which air flows from outside the housing 13. An
15 electronic device 1 in FIG. 10 is described below focusing on the differences in the
structures from the electronic device 1 in FIG. 7.
[0076] The electronic device 1 includes a partition 18 that divides an internal space
of the housing 13 into a first space 19a allowing less air flowing in from outside the
housing 13 and a second space 19b allowing air flowing in from outside the housing 13.
20 The housing 13 has multiple openings 13c in the surface facing the second space 19b, and
air from outside the housing 13 flows into the second space 19b through the openings
13c.
[0077] The partition 18 includes an opening 18a. The cooler 26 closes the
opening 18a with a portion located in the second space 19b. With the opening 18a
25 closed with a portion of the cooler 26, air outside the housing 13 containing dust,
moisture, and other foreign matter is less likely to flow into the first space 19a through
the opening 18a. More specifically, the heat-receiving block 27 closes the opening 18a
22
from inside the first space 19a, with the heat dissipater 28 being exposed to the second
space 19b. The heat dissipater 28 being exposed to the second space 19b dissipates heat
transferred from the heat-receiving block 27 to air flowing into the second space 19b
from outside the housing 13. The capacitor elements 21a, 21b, 21c, 21d, 31a, 31b, 31c,
5 and 31d are thus cooled.
[0078] In another example, the openings 13a and 13b illustrated in FIG. 7 may be
located on the same surface of the housing 13, and the switching elements SW may be
thermally connected to the cooler 26. In other words, the capacitor unit 11 and the
switching elements SW may be cooled with a common cooling device. In this case, the
10 main surfaces 27a and 27b of the heat-receiving block 27 may be sized to accommodate
the switching elements SW, in addition to the insulating member 25.
[0079] The insulating member 25 may be fixed to the heat-receiving block 27 with
any method. In one example, the insulating member 25 may be bonded to the heatreceiving block 27 with an adhesive.
15 [0080] The electronic device 1 illustrated in FIG. 7 may include the capacitor unit
11 illustrated in FIG. 3. In this case, the insulating member 25 may be attached to the
inner surface of the housing 13 with the opening 13a illustrated in FIG. 7 closed with the
insulating member 25. Similarly, the electronic device 1 illustrated in FIG. 10 may
include the capacitor unit 11 illustrated in FIG. 3. In this case, the insulating member
20 may be attached to the partition 18 with the opening 18a illustrated in FIG. 10 closed with
the insulating member.
[0081] The electronic device 1 is not limited to a three-level power conversion
apparatus, but may be any device including the capacitor unit 11. In one example, the
electronic device 1 may be a rectifier. The electronic device 1 is mountable on, in
25 addition to a railway vehicle, any movable body such as an automobile, a ship, or an
aircraft.
[0082] The load 51 is not limited to a three-phase induction motor, but may be any
23
device that receives power supplied from the electronic device 1. The load 51 is, for
example, an air-conditioner or an illuminator.
[0083] The foregoing describes some example embodiments for explanatory
purposes. Although the foregoing discussion has presented specific embodiments,
5 persons skilled in the art will recognize that changes may be made in form and detail
without departing from the broader spirit and scope of the invention. Accordingly, the
specification and drawings are to be regarded in an illustrative rather than a restrictive
sense. This detailed description, therefore, is not to be taken in a limiting sense, and the
scope of the invention is defined only by the included claims, along with the full range of
10 equivalents to which such claims are entitled.
Reference Signs List
[0084]
1 Electronic device
1a Positive terminal
15 1b Negative terminal
11 Capacitor unit
12 Power converter
13 Housing
13a, 13b, 13c, 18a Opening
20 14 Power converter cooler
15, 27 Heat-receiving block
15a, 15b, 27a, 27b Main surface
16, 28 Heat dissipater
17 Laminate busbar
25 18 Partition
19a First space
19b Second space
24
21a, 21b, 21c, 21d, 31a, 31b, 31c, 31d Capacitor element
22a, 22b, 22c, 29a, 29b, 29c, 32a, 32b, 32c, 35a, 35b, 35c Heat transfer member
23a, 33a First busbar
23b, 33b Second busbar
5 24a, 34a First terminal
24b, 34b Second terminal
25 Insulating member
26 Cooler
41a Positive electrode
10 41b Negative electrode
41c, 41d Film
51 Load
C1 First capacitor
C2 Second capacitor
15 SW Switching element
25
We Claim :
[Claim 1] A capacitor unit, comprising:
a plurality of capacitor elements; and
one or more heat transfer members located adjacent to at least one capacitor
5 element of the plurality of capacitor elements and configured to internally dissipate heat
received from the at least one capacitor element of the plurality of capacitor elements.
[Claim 2] The capacitor unit according to claim 1, further comprising:
an insulating member to fix a position of the one or more heat transfer members
10 relative to the plurality of capacitor elements by covering at least a portion of each of the
one or more heat transfer members and the plurality of capacitor elements.
[Claim 3] The capacitor unit according to claim 1 or 2, wherein
each of the one or more heat transfer members is a plate with at least one main
15 surface in contact with the at least one capacitor element of the plurality of capacitor
elements.
[Claim 4] The capacitor unit according to claim 1 or 2, wherein
each of the one or more heat transfer members is a rod in contact with the at least
20 one capacitor element of the plurality of capacitor elements.
[Claim 5] The capacitor unit according to any one of claims 1 to 4, wherein
the one or more heat transfer members include a plurality of heat transfer members
each located adjacent to a different capacitor element of the plurality of capacitor
25 elements.
[Claim 6] The capacitor unit according to any one of claims 1 to 5, further
26
comprising:
a cooler thermally connected to the one or more heat transfer members and
configured to dissipate heat transferred from the plurality of capacitor elements through
the one or more heat transfer members.
5
[Claim 7] The capacitor unit according to claim 6, wherein
each of the one or more heat transfer members is located between two adjacent
capacitor elements of the plurality of capacitor elements, and each of the one or more heat
transfer members transfers heat received from the two adjacent capacitor elements to the
10 cooler.
[Claim 8] The capacitor unit according to claim 6 or 7, wherein
the one or more heat transfer members are in contact with the cooler.
15 [Claim 9] The capacitor unit according to any one of claims 6 to 8, wherein
the cooler includes
a heat-receiving block thermally connected to the one or more heat transfer
members, and
a heat dissipater to dissipate heat transferred from the heat-receiving block.
20
[Claim 10] An electronic device, comprising:
the capacitor unit according to any one of claims 1 to 9.
[Claim 11] An electronic device, comprising:
25 the capacitor unit according to any one of claims 6 to 8;
a power converter to convert power supplied from a power supply through the
capacitor unit to power to be supplied to a load and output the power resulting from
27
conversion; and
a housing accommodating the capacitor unit and the power converter,
wherein the cooler in the capacitor unit dissipates heat transferred from the
plurality of capacitor elements through the one or more heat transfer members to air
5 outside the housing.
[Claim 12] The electronic device according to claim 11, further comprising:
a partition dividing an internal space of the housing into a first space and a second
space, the first space accommodating the capacitor unit and the power converter and
10 suppressing air flowing in from outside the housing, the second space allowing air
flowing in from outside the housing,
wherein the cooler in the capacitor unit closes an opening in the partition, with a
portion of the cooler being exposed to the second space through the opening.
15 [Claim 13] The electronic device according to claim 11, wherein
the cooler in the capacitor unit closes an opening in the housing, with a portion of
the cooler being exposed outside the housing through the opening.
[Claim 14] The electronic device according to any one of claims 11 to 13, further
20 comprising:
a power converter cooler to dissipate heat transferred from the power converter to
air outside the housing.