U.S. patent application number 13/984846 was filed with the patent office on 2013-12-05 for cooling device and power conversion device.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Tomohiro Kobayashi, Yukio Nakashima, Yoshitaka Ono. Invention is credited to Tomohiro Kobayashi, Yukio Nakashima, Yoshitaka Ono.
Application Number | 20130319635 13/984846 |
Document ID | / |
Family ID | 46170958 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130319635 |
Kind Code |
A1 |
Kobayashi; Tomohiro ; et
al. |
December 5, 2013 |
COOLING DEVICE AND POWER CONVERSION DEVICE
Abstract
A heat sink is arranged between a radiator and a circulating
pump. A first path length that is a path length between the
radiator along a cooling pipe on a side not including the
circulating pump and the heat sink and a second path length that is
a path length between the circulating pump along the cooling pipe
on a side not including the radiator and the heat sink are set to
be shorter than a third path length that is a path length between
the radiator along the cooling pipe on a side not including the
heat sink and the circulating pump. A metal spiral that is a metal
material having a high conductivity is spirally wound around the
cooling pipe so as to contact an outer circumferential surface of
the cooling pipe.
Inventors: |
Kobayashi; Tomohiro; (Tokyo,
JP) ; Ono; Yoshitaka; (Tokyo, JP) ; Nakashima;
Yukio; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kobayashi; Tomohiro
Ono; Yoshitaka
Nakashima; Yukio |
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Chiyoda-ku, Tokyo
JP
|
Family ID: |
46170958 |
Appl. No.: |
13/984846 |
Filed: |
February 10, 2011 |
PCT Filed: |
February 10, 2011 |
PCT NO: |
PCT/JP2011/052942 |
371 Date: |
August 10, 2013 |
Current U.S.
Class: |
165/104.11 |
Current CPC
Class: |
H05K 7/20927 20130101;
H01L 2924/0002 20130101; H01L 23/473 20130101; H01L 2924/0002
20130101; B61C 17/00 20130101; F28D 15/00 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
165/104.11 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. A cooling device of a circulating-liquid cooling system that
connects two of respective elements of a heat exchanger, a
circulating pump, and a cooled body by a cooling pipe, wherein the
cooled body is arranged between the heat exchanger and the
circulating pump, each of a first path length that is a path length
between the heat exchanger along the cooling pipe on a side not
including the circulating pump and the cooled body and a second
path length that is a path length between the circulating pump
along the cooling pipe on a side not including the heat exchanger
and the cooled body is set to be shorter than a third path length
that is a path length between the heat exchanger along the cooling
pipe on a side not including the cooled body and the circulating
pump, and a metal material having a high thermal conductivity is
spirally wound around the cooling pipe so as to contact an outer
circumferential surface of the cooling pipe.
2. A cooling device of a circulating-liquid cooling system that
connects two of respective elements of a heat exchanger, a
circulating pump, and a cooled body by a cooling pipe, wherein the
cooled body is arranged between the heat exchanger and the
circulating pump, each of a first path length that is a path length
between the heat exchanger along the cooling pipe on a side not
including the circulating pump and the cooled body and a second
path length that is a path length between the circulating pump
along the cooling pipe on a side not including the heat exchanger
and the cooled body is set to be shorter than a third path length
that is a path length between the heat exchanger along the cooling
pipe on a side not including the cooled body and the circulating
pump, and a metal material having a high thermal conductivity is
spirally wound around a part of the third path length of the
cooling pipe so as to contact an outer circumferential surface of
the cooling pipe, and a cooling pipe itself of parts of the first
and second path lengths is made of a metal material having a high
thermal conductivity.
3. The cooling device according to claim 2, wherein a freezing
temperature of a cooling liquid that circulates in the cooling pipe
is set to be lower than a minimum temperature in specifications
applied to the cooling device.
4. The cooling device according to claim 3, wherein a switching
element module that configures the cooled body is formed of a wide
bandgap semiconductor.
5. The cooling device according to claim 4, wherein the wide
bandgap semiconductor is a semiconductor using silicon carbide, a
gallium nitride-based material, or diamond.
6. (canceled)
7. A power conversion device that is configured so that a switching
element module serving as a cooled body can be cooled by a cooling
device of a circulating-liquid cooling system, wherein in the
cooling device, two of respective elements of a heat exchanger, a
circulating pump, and the cooled body are connected by a cooling
pipe, and the cooled body is arranged between the heat exchanger
and the circulating pump, each of a first path length that is a
path length between the heat exchanger along the cooling pipe on a
side not including the circulating pump and the cooled body and a
second path length that is a path length between the circulating
pump along the cooling pipe on a side not including the heat
exchanger and the cooled body is set to be shorter than a third
path length that is a path length between the heat exchanger along
the cooling pipe on a side not including the cooled body and the
circulating pump, and a metal material having a high thermal
conductivity is spirally wound around the cooling pipe so as to
contact an outer circumferential surface of the cooling pipe.
8. A power conversion device that is configured so that a switching
element module serving as a cooled body can be cooled by a cooling
device of a circulating-liquid cooling system, wherein in the
cooling device, two of respective elements of a heat exchanger, a
circulating pump, and the cooled body are connected by a cooling
pipe, and the cooled body is arranged between the heat exchanger
and the circulating pump, each of a first path length that is a
path length between the heat exchanger along the cooling pipe on a
side not including the circulating pump and the cooled body and a
second path length that is a path length between the circulating
pump along the cooling pipe on a side not including the heat
exchanger and the cooled body is set to be shorter than a third
path length that is a path length between the heat exchanger along
the cooling pipe on a side not including the cooled body and the
circulating pump, and a metal material having a high thermal
conductivity is spirally wound around a part of the third path
length of the cooling pipe so as to contact an outer
circumferential surface of the cooling pipe, and a cooling pipe
itself of parts of the first and second path lengths is made of a
metal material having a high thermal conductivity.
9. The power conversion device according to claim 8, wherein a
freezing temperature of a cooling liquid that circulates in the
cooling pipe is set to be lower than a minimum temperature in
specifications applied to the cooling device.
10. The power conversion device according to claim 9, wherein a
switching element module that configures the cooled body is formed
of a wide bandgap semiconductor.
11. The power conversion device according to claim 10, wherein the
wide bandgap semiconductor is a semiconductor using silicon
carbide, a gallium nitride-based material, or diamond.
12. (canceled)
13. The cooling device according to claim 1, wherein the cooled
body is a switching element that is applied for a power conversion
device.
14. The cooling device according to claim 13, wherein the switching
element is formed of a wide bandgap semiconductor.
15. The cooling device according to claim 1, wherein a freezing
temperature of a cooling liquid that circulates in the cooling pipe
is set to be lower than a minimum temperature in specifications
applied to the cooling device.
16. The cooling device according to claim 15, wherein a switching
element module that configures the cooled body is formed of a wide
bandgap semiconductor.
17. The cooling device according to claim 16, wherein the wide
bandgap semiconductor is a semiconductor using silicon carbide, a
gallium nitride-based material, or diamond.
18. The cooling device according to claim 2, wherein the cooled
body is a switching element that is applied for a power conversion
device.
19. The cooling device according to claim 18, wherein the switching
element is formed of a wide bandgap semiconductor.
20. The power conversion device according to claim 7, wherein a
freezing temperature of a cooling liquid that circulates in the
cooling pipe is set to be lower than a minimum temperature in
specifications applied to the cooling device.
21. The power conversion device according to claim 20, wherein a
switching element module that configures the cooled body is formed
of a wide bandgap semiconductor.
22. The power conversion device according to claim 21, wherein the
wide bandgap semiconductor is a semiconductor using silicon
carbide, a gallium nitride-based material, or diamond.
Description
FIELD
[0001] The present invention relates to a cooling device of a
circulating-liquid cooling system and a power conversion device
that is configured to be coolable by this type of cooling
device.
BACKGROUND
[0002] According to a cooling device of a circulating-liquid
cooling system, as a coolant (a cooling liquid) of the cooling
device, it has been conventionally required to add a required
amount of additive to the coolant to reduce the freezing
temperature of the cooling liquid to be lower than a minimum
temperature in specifications required for the cooling device. The
additive for reducing the freezing temperature generally causes
degradation in cooling performance. Therefore, there is a problem
that, to achieve sufficient cooling performance in a high
temperature state, the size of the cooling device becomes
large.
[0003] Meanwhile, Patent Literature 1 mentioned below discloses the
following technique. That is, in a case where an inverter device is
connected to a cooling device by a cooling pipe, cooling water from
the cooling device is caused to pass through the cooling pipe and
circulate therethrough to cool the inverter device, when the
temperature of the cooling water is reduced because of a reduction
in an outdoor air temperature, the inverter device is caused to
perform no-load running to generate heat and the temperature of the
cooling water is increased by the heat, thereby preventing freezing
of the cooling water.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Patent Application Laid-open
No. H09-199648
SUMMARY
Technical Problem
[0005] However, the technique disclosed in Patent Literature 1
mentioned above is a technique of preventing freezing of a cooling
device, and thus there is a problem that when freezing of the
cooling device is expected, the inverter device needs to be
operated even though the cooling device is in a non-operating
state.
[0006] It is conceivable to use the technique described in Patent
Literature 1 mentioned above and configure a cooling device that
allows temporary freezing in its non-operating state. However,
according to such a device, for example, in a case where a part of
a cooling pipe through which a cooling liquid passes is long, even
when the inverter device is caused to perform no-load running to
generate heat, while a circulation cooling function is not
performed because a part of the cooling pipe is still frozen, the
temperature of a semiconductor switching element serving as a
cooled body exceeds an allowable maximum temperature. Accordingly,
there is a problem that when the inverter device continues running
in this state, the semiconductor switching element may be
damaged.
[0007] In a case of such a device, it is also conceivable that
no-load running of the inverter device is temporarily stopped to
wait until the temperature of the semiconductor switching element
is reduced and then the no-load running is performed again.
However, with this method, the inverter device needs to be run and
stopped repeatedly and thus there is a problem that it requires a
long time to cause the cooling device to be in an operating
state.
[0008] The present invention has been achieved in view of the above
problems, and an object of the present invention is to provide a
cooling device that allows temporary freezing in a non-operating
state without executing any warming control for preventing freezing
and that effectively melts a frozen cooling liquid in a cooling
pipe without using any preheating device and the like to be capable
of shifting to an operable state in a short time, and a power
conversion device including the cooling device.
Solution to Problem
[0009] In order to solve the above problem and in order to attain
the above object, in a cooling device regarding the present
invention of a circulating-liquid cooling system that connects two
of respective elements of a heat exchanger, a circulating pump, and
a cooled body by a cooling pipe, the cooled body is arranged
between the heat exchanger and the circulating pump, each of a
first path length that is a path length between the heat exchanger
along the cooling pipe on a side not including the circulating pump
and the cooled body and a second path length that is a path length
between the circulating pump along the cooling pipe on a side not
including the heat exchanger and the cooled body is set to be
shorter than a third path length that is a path length between the
heat exchanger along the cooling pipe on a side not including the
cooled body and the circulating pump, and a metal material having a
high conductivity is spirally wound around the cooling pipe so as
to contact an outer circumferential surface of the cooling
pipe.
Advantageous Effects of Invention
[0010] The present invention can provide a cooling device that
allows temporary freezing in a non-operating state without
executing any warming control for preventing freezing and that
effectively melts a frozen cooling liquid in a cooling pipe without
using any preheating device and the like to be capable of shifting
to an operable state in a short time, and a power conversion device
including the cooling device.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a schematic diagram of a cooling configuration of
a cooling device according to a first embodiment.
[0012] FIG. 2 depicts a circuit configuration of a power conversion
device according to the first embodiment.
[0013] FIG. 3 depicts a configuration including temperature sensors
at periphery parts of a radiator and a circulating pump.
[0014] FIG. 4 is a schematic diagram of a cooling configuration of
a cooling device according to a second embodiment.
DESCRIPTION OF EMBODIMENTS
[0015] Exemplary embodiments of a cooling device and a power
conversion device according to the present invention will be
explained below in detail with reference to the accompanying
drawings. The present invention is not limited to the
embodiments.
First Embodiment
[0016] FIG. 1 is a schematic diagram of a cooling configuration of
a cooling device according to a first embodiment of the present
invention. In FIG. 1, a cooling pipe 5 is a flexible hollow pipe
made of a material such as resin, and connects a switching element
module 10 that is a heat generation source and also serves as a
cooled body, a radiator 6 that is a heat exchanger that cools a
cooling liquid serving as a cooling medium, a circulating pump 7
for circulating the cooling liquid, and a reserve tank 8 that
replenishes a cooling liquid to absorb a change in the volume of
the cooling liquid. A blower 9 for forcibly cooling the cooling
liquid is mounted on the radiator 6. The switching element module
10 is configured to include a switching element 3 and a heat sink
4, and the cooling pipe 5 is inserted into the heat sink 4.
[0017] The switching element module 10 is arranged between the
radiator 6 and the circulating pump 7. In view of the overall
configuration of the cooling pipe 5, the switching element module
10, the radiator 6, and the circulating pump 7 are arranged
adjacently. A metal spiral 20 formed by spirally winding a metal
material is provided on the cooling pipe 5. This metal spiral 20 is
wound so as to closely contact an outer circumferential surface of
the cooling pipe 5 and so that spiral parts are closely adjacent to
each other, thereby swiftly moving heat generated in the switching
element module 10 to every part of the cooling pipe 5.
[0018] As shown in FIG. 1, the cooling pipe 5 is divided into three
parts, that is, cooling pipes 5a, 5b, and 5c. The cooling pipe 5a
is a part arranged between the radiator 6 and the heat sink 4, the
cooling pipe 5b is a part arranged between the heat sink 4 and the
circulating pump 7, and the cooling pipe 5c is a part arranged
between the radiator 6 and the circulating pump 7. It is assumed
that a path length of the cooling pipe 5a, that is, a path length
(a first path length) between the radiator 6 along the cooling pipe
5 on a side not including the circulating pump 7 and the heat sink
4 (the switching element module 10) is denoted by A. Similarly, it
is assumed that a path length of the cooling pipe 5b, that is, a
path length (a second path length) between the circulating pump 7
along the cooling pipe 5 on a side not including the radiator 6 and
the heat sink 4 (the switching element module 10) is denoted by B,
and a path length of the cooling pipe 5c, that is, a path length (a
third path length) between the radiator 6 along the cooling pipe 5
on a side not including the heat sink 4 (the switching element
module 10) and the circulating pump 7 is denoted by C. When the
respective path lengths are defined as described above,
relationships of A<C and B<C are established between these
first to third path lengths. Meanwhile, a relationship between A
and B is not uniquely determined because the magnitude relationship
therebetween may change depending on a heat capacity of the
radiator 6 and the circulating pump 7. Relationships among the path
lengths A, B, and C are described in more detail later.
[0019] As the cooling liquid in the cooling pipe 5, it is possible
to use water, an aqueous solution containing additive (for example,
ethylene glycol) that suppresses freezing of the cooling liquid at
a low temperature, or an oleaginous solution. A cooling liquid that
brings out the significance and effects of the cooling device
according to the present embodiment most is water in which an
antifreezing liquid such as ethylene glycol is not mixed. Because
the antifreezing liquid reduces a heat conductivity of the cooling
liquid and its cooling performance, it is preferable to avoid
mixing of any impurity with the cooling liquid as much as
possible.
[0020] FIG. 2 depicts a circuit configuration of a power conversion
device according to the first embodiment. The power conversion
device shown in FIG. 2 is a configuration example of a power
conversion device applied to an alternating-current-input electric
vehicle, and is configured to include a converter unit 1, an
inverter unit 2, and a filter capacitor 14.
[0021] In FIG. 2, an alternating current collected from an overhead
line 11 via a pantograph 12 is stepped down by a transformer 13 and
is converted into a direct current by the converter unit 1. The
power converted into a direct current is output via the filter
capacitor 14 to an induction motor 15 as a three-phase alternating
current of a variable-voltage variable-frequency generated by the
inverter unit 2 to control acceleration and deceleration of, for
example, an electric vehicle having the induction motor 15 being
incorporated therein.
[0022] A plurality of the switching elements 3 that configure the
converter unit 1 and the inverter unit 2 described above are
configured by using, for example, a self-extinction semiconductor
device such as an IGBT (Insulated Gate Bipolar Transistor). In the
case of the switching element 3 according to the present
embodiment, as shown in FIG. 2, a switching element in which an
IGBT 16 and a diode 17 connected in antiparallel to the IGBT 16 are
integrally modularized is exemplified.
[0023] While FIG. 2 depicts a case of applying the power conversion
device according to the first embodiment to the
alternating-current-input electric vehicle as a preferable example
of the power conversion device, the power conversion device can be
similarly applied to a direct-current-input electric vehicle that
is widely used for a subway, a suburban electric vehicle, and the
like. When the power conversion device is applied to the
direct-current-input electric vehicle, the configuration thereof
can be identical to that of FIG. 2, except that the transformer 13
and the converter unit 1 become unnecessary, and it is needless to
mention that the contents of the present embodiment can be also
applied to the direct-current-input electric vehicle.
[0024] Next, an operation of the cooling device according to the
present embodiment at a normal time is explained. In the
configuration described above, when the power conversion device is
operated, the switching element 3 generates heat. The switching
element 3 is cooled by the heat sink 4. Meanwhile, a cooling liquid
whose temperature is increased by heat radiation from the switching
element 3 via the heat sink 4 is moved in the cooling pipe 5 by the
circulating pump 7 and is cooled in the radiator 6 by heat exchange
with air. An increase in the temperature of the switching element 3
is suppressed in this way, and a continuous operation of the power
conversion device can be performed.
[0025] Next, a precondition in the cooling device according to the
present embodiment is explained. The precondition is that a
freezing temperature of a coolant (a cooling liquid) used for the
cooling device according to the present embodiment is higher than a
minimum temperature in specifications applied to the cooling
device. In a case where the minimum temperature in the
specifications applied to the cooling device is -10.degree. C., for
example, when water is used as the coolant, for example, a
relationship of "minimum temperature (-10.degree. C.)<freezing
temperature (0.degree. C.)" is established. Furthermore, in a case
where the minimum temperature in the specifications applied to the
cooling device is -40.degree. C., for example, even when a required
amount of ethylene glycol, for example, is added as an antifreezing
agent to the coolant to set the freezing temperature to about
-20.degree. C., for example, a relationship of "minimum temperature
(-40.degree. C.)<freezing temperature (-20.degree.)" is
established.
[0026] In a case where the minimum temperature in the
specifications applied to the cooling device is -40.degree. C., for
example, when an outdoor air temperature is -50.degree. C. because
of a severe cold wave that may happen once in ten-odd years,
unexpected freezing of the cooling liquid occurs. However, when a
cooling device is configured with the precondition described above,
that is, when a cooling device is configured while assuming that a
cooling liquid is frozen, it is possible to handle such unexpected
freezing of the cooling liquid swiftly and without any problem.
Furthermore, there is an advantage such that even though the device
is not designed to handle events that occur with a very low
probability, the device can handle such events. This advantage can
greatly contribute to cost reduction and downsizing of the
device.
[0027] Next, an operation of the cooling device according to the
present embodiment at the time of freezing is explained with
reference to FIG. 1. When a cooling liquid is frozen, the cooling
liquid does not circulate in the cooling pipe 5 and thus a cooling
device does not function. Meanwhile, according to the cooling
device of the present embodiment, when the cooling liquid is
frozen, the switching element module 10 is forcibly operated. When
the switching element module 10 is operated, the switching element
3 generates heat and thus the amount of the heat is moved to the
heat sink 4 and transferred to the metal spiral 20. The metal
spiral 20 is formed by using a material having a high conductivity
such as copper or silver. Furthermore, according to the cooling
device of the present invention, because a path length between the
heat sink 4 and the radiator 6 and a path length between the heat
sink 4 and the circulating pump 7 are short, heat transfer to the
radiator 6 and the circulating pump 7 that have a large heat
capacity is performed in a short time.
[0028] When the cooling liquid in the radiator 6 and the
circulating pump 7 that have a large heat capacity is melted, any
other structures having a large capacity do not exist other than
the cooling pipe 5. When the cooling liquid in the radiator 6 and
the circulating pump 7 that have a large heat capacity is melted,
it is expected that a part of the cooling liquid in the cooling
pipe 5c is also melted and the entire cooling liquid is liquefied
in a sherbet state. Accordingly, by operating the circulating pump
7 in addition to the switching element module 10, effects of heat
transfer are increased and a speed at which the cooling device
enters in an operable state can be increased. For example, as shown
in FIG. 3, it suffices to respectively provide temperature sensors
18a and 18b at periphery parts of the radiator 6 and the
circulating pump 7 and to operate the circulating pump 7 when
either the temperature sensor 18a or 18b has a value equal to or
larger than a predetermined value.
[0029] The number of temperature sensors does not need to be two.
It is permissible to provide only one temperature sensor, or to
provide three or more temperature sensors. The position of the
temperature sensor is not particularly limited as long as it is on
a circulation path of the cooling liquid, but it is more preferable
that the temperature sensor is provided at the periphery part of
the radiator 6 or the circulating pump 7.
[0030] As shown in FIG. 1, in the present embodiment, while the
reserve tank 8 is arranged on the cooling pipe 5c that is the
longest among cooling pipes, the reserve tank 8 can be connected to
other pipe parts (the cooling pipes 5a and 5b) because the heat
capacity of the reserve tank 8 is not larger than that of the
radiator 6 and the circulating pump 7.
[0031] While the present embodiment has explained that the
magnitude relationship between the first path length A and the
second path length B is not uniquely determined. However, when a
different in the heat capacity between the radiator 6 and the
circulating pump 7 is large, to allow a structure having a large
heat capacity and a structure having a small heat capacity to be
melted substantially at the same time, it suffices to arrange a
cooling pipe so that a path length of a cooling pipe connected to
the structure having a large heat capacity is short.
[0032] While the present embodiment has described a material having
a high heat conductivity such as copper or silver as the metal
material (the metal spiral) that is spirally wound around the
cooling tube 5, the metal material is not limited to this type of
metal material. For example, it is believed that some carbon
nanotubes have a heat conductivity that is ten to ten-odd times
larger than that of silver or copper. While the system of supplying
carbon nanotubes has not been fully established as of filing of the
present application, a technique related to the carbon nanotubes
will become a breakthrough technique and it is preferable to use
the carbon nanotubes for the cooling device according to the
present embodiment.
[0033] While the present embodiment has described that the metal
material is wound around the entire circumference of the cooling
pipe 5 as shown in FIG. 1, the present invention is not limited
thereto. For example, the metal material can be wound around only
the cooling pipe 5a or the cooling pipe 5b, for example.
[0034] As explained above, according to the cooling device of the
present embodiment, the cooling performance at a high temperature
can be improved without using any additive that reduces a freezing
temperature, or even when the additive is used, by suppressing the
amount of the additive. Furthermore, any additional device such as
a preheating device or a warming device is unnecessary.
[0035] According to the cooling device of the present embodiment,
because any additive that reduces the freezing temperature is not
used, or even when it is used, the amount of the additive can be
suppressed, the cooling performance at a high temperature can be
improved, and the device can be downsized with the same cooling
performance.
[0036] According to the cooling device of the present embodiment,
because a pipe made of flexible resin can be used as a cooling
pipe, the cooling pipe can be arranged with flexibility.
[0037] According to the cooling device of the present embodiment, a
metal material is spirally wound around the cooling pipe to closely
and adjacently contact the cooling pipe, so that, even when the
heat generation source suddenly generates heat, the cooling liquid
in the overall cooling device is rapidly liquefied to recover a
cooling function. Furthermore, there is adopted a configuration in
which a switching element module serving as a heat generation
source is arranged between a radiator and a circulating pump.
Accordingly, the cooling device can be caused to shift to an
operable state before the switching element reaches a maximum
allowable temperature.
[0038] According to the cooling device of the present invention,
because the device is configured while assuming that a cooling
liquid is frozen, it is possible to handle such unexpected freezing
of the cooling liquid swiftly and without any problem. Furthermore,
there is an advantage such that even though the device is not
designed to handle events that occur with a very low probability,
the device can handle such events. This advantage can greatly
contribute to cost reduction and downsizing of the device.
Second Embodiment
[0039] FIG. 4 is a schematic diagram of a cooling configuration of
a cooling device according to a second embodiment of the present
invention. According to the cooling device of the first embodiment,
the metal spiral 20 is wound around the cooling pipe 5a arranged
between the radiator 6 and the heat sink 4 and the cooling pipe 5b
arranged between the heat sink 4 and the circulating pump 7. On the
other hand, according to the second embodiment, these cooling pipes
5a and 5b are configured as cooling pipes 5a' and 5b' serving as a
metal pipe.
[0040] When the flexible cooling pipes 5a and 5b are used as in the
first embodiment, while a cooling pipe can be flexibly arranged,
the metal spiral 20 needs to be wound around the cooling pipes 5a
and 5b. On the other hand, when the metal cooling pipes 5a' and 5b'
are used as in the present embodiment, any operation of winding the
metal spiral 20 around the cooling pipes 5a' and 5b' is
unnecessary. Furthermore, in a case of the cooling device according
to the first and second embodiments, because a distance between the
radiator 6 and the heat sink 4 and a distance between the
circulating pump 7 and the heat sink 4 are short, a metal pipe
having a high heat conductivity can be used.
[0041] It is preferable to form the cooling pipes 5a' and 5b' by
using metal having a high heat conductivity such as silver or
copper. When the metal having a high heat conductivity is used,
heat transfer between the radiator 6 and the heat sink 4 and
between the circulating pump 7 and the heat sink 4 is swiftly
performed and thus effects identical to those of the first
embodiment can be achieved.
Third Embodiment
[0042] A third embodiment explains a switching element included in
the converter unit 1 and the inverter unit 2 of a power conversion
device. As the switching element used in the power conversion
device, a switching element in which a semiconductor transistor
element made of silicon (Si) (an IGBT, a MOSFET, and the like) is
connected in antiparallel to a semiconductor diode element also
made of silicon is generally used. The techniques explained in the
first and second embodiments can be used for an inverter unit and a
converter unit each of which includes such a general switching
element.
[0043] Meanwhile, the techniques explained in the first and second
embodiments are not limited to a switching element made of silicon.
It is of course possible to include a switching element made of,
instead of silicon, silicon carbide (SiC) that has recently
attracted attention in the converter unit 1 and the inverter unit
2.
[0044] Because silicon carbide has a characteristic that it can be
used at a high temperature, when the switching element made of
silicon carbide is used as the switching element included in the
converter unit 1 or the inverter unit 2, an allowable operating
temperature of a switching element module can be raised to be a
high temperature. Therefore, when the switching element made of
silicon carbide is used, the switching element can be caused to
remain in an allowable temperature region even when the amount of
heat generation per unit time is increased, and a melting speed of
a frozen cooling liquid can be increased as compared to a case
where the switching element made of silicon is used.
[0045] Silicon carbide (SiC) is an example of a semiconductor
referred to as "wide bandgap semiconductor", because of a
characteristic that it has a bandgap larger than silicon (Si). In
addition to this silicon carbide, for example, a semiconductor made
of a gallium nitride-based material or a semiconductor formed by
using diamond are also a wide bandgap semiconductor and
characteristics of these materials are similar to those of silicon
carbide. Therefore, configurations using a wide bandgap
semiconductor other than that made of silicon carbide also form the
scope of the present invention.
[0046] Because a transistor element and a diode element that are
formed of such a wide bandgap semiconductor have a high voltage
resistance and a high allowable current density, the transistor
element and the diode element can be downsized. By using these
downsized transistor element and diode element, a semiconductor
module having these elements incorporated therein can be
downsized.
[0047] Because the transistor element and the diode element formed
of a wide bandgap semiconductor also have a high heat resistance, a
heat sink can be downsized and a switching element module can be
further downsized.
[0048] Furthermore, because the transistor element and the diode
element formed of a wide bandgap semiconductor have a reduced power
loss, the efficiency of the switching element and the diode element
can be increased and thus the efficiency of the switching element
module can be increased.
INDUSTRIAL APPLICABILITY
[0049] As described above, the present invention is useful as a
cooling device of a circulating-liquid cooling system and a power
conversion device that is configured to be coolable by this type of
cooling device.
REFERENCE SIGNS LIST
[0050] 1 converter unit
[0051] 2 inverter unit
[0052] 3 switching element
[0053] 4 heat sink
[0054] 5, 5a, 5b, 5c, 5a',5b' cooling pipe
[0055] 6 radiator
[0056] 7 circulating pump
[0057] 8 reserve tank
[0058] 9 blower
[0059] 10 switching element module
[0060] 11 overhead line
[0061] 12 pantograph
[0062] 13 transformer
[0063] 14 filter capacitor
[0064] 15 induction motor
[0065] 16 IGBT
[0066] 17 diode
[0067] 20 metal spiral
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