1. A cooling structure of a heating element comprising: a plurality of heating elements each having opposing two surfaces, at least one of the two surfaces being a cooling surface (760A, 760B); and a heat receiving block (601) having a plurality of insertion openings (604, 605, 606) for inserting therein respective the plurality of heating elements, wherein an area in which the plurality of insertion openings (604, 605, 606) is not formed of the heat receiving block (601) includes a unshared cooling (801) portion configured to receive heat from the cooling surface (760A, 760B) of corresponding one of the plurality of heating elements, and a shared cooling portion (800) sandwiched between corresponding adjacent two of the plurality of insertion openings (604, 605, 606), the shared cooling portion (800) being configured to receive heat from corresponding adjacent two of the plurality of heating elements, and wherein an amount of heat in the shared cooling portion (800), the heat being received from the corresponding adjacent two of the plurality of heating elements, is larger than an amount of heat in the unshared cooling portion (801), the heat being received from the corresponding one of the plurality of heating elements.

2. The cooling structure of a heating element according to claim 1, wherein a heat transfer member is provided in each of the shared cooling portion (800) and the unshared cooling portion (801), and a heat amount transported by the heat transfer member provided in the shared cooling portion (800) is larger than a heat amount transported by the heat transfer member provided in the unshared cooling (801) portion.

3. The cooling structure of a heating element according to claim 1, wherein the heating element is a power module (500, 606, 700), and the cooling structure further comprising a heat radiating fin (603) provided in a direction opposite to an extending direction in which a terminal of the power module (500, 606, 700) extends toward an external side of a body of the power module (500, 606, 700), the heat radiating fin (603) being configured to cool the heating element.

4. The cooling structure of a heating element according to claim 2, wherein the heat transfer member has therein a wick structure and includes therein operating liquid (2202), and the wick structure makes a capillary tube force (2203) acting on the operating liquid (2202) act more than gravitational force.

5. The cooling structure of a heating element according to claim 1, wherein - 24 - the number of heat transfer members provided in the shared cooling portion (800) is larger than the number of heat transfer members provided in the unshared cooling portion (801).

6. The cooling structure of a heating element according to claim 1, wherein an inner diameter of the heat transfer member provided in the shared cooling portion (800) is larger than an inner diameter of the heat transfer member provided in the unshared cooling portion (801).

7. A fixing structure of the heating element according to claim 1, comprising: a pair of heat receiving plates provided to cover respective the two surfaces of the heating element; and an elastic member provided in an area in which the pair of heat receiving plates face to each other, wherein when the heating element and the pair of heat receiving plates are inserted in one of the plurality of insertion openings (604, 605, 606), a pressing force to make the pair of the heat receiving plates contact with respective inner wall surfaces of the one of the plurality of insertion openings (604, 605, 606) is applied by the elastic member (801).

8. A power conversion device (100, 1200) wherein, a capacitor (201, 301, 401, 1105, 1605) is connected to a bus bar (1104, 1106) to which the cooling structure of a heating element according to claim 1 is connected, and a body part of the capacitor (201, 301, 401, 1105, 1605) is provided on a side, with respect to the bus bar (1104, 1106), of an area in which the cooling structure is provided.

INCORPORATION BY REFERENCE
The present application claims priority from Japanese application JP 2015-232593 filed on
November 30, 2015, the content of which is hereby incorporated by reference into this
application.
BACKGROUND OF THE INVENTION
[0001]
The present invention relates to a cooling structure for a heating element, and also
to a power conversion device.
[5 0002]
JP 2006-286676 A, for example, discloses a technique as a structure to attach a
heating element to a heat radiation member in case that a heating element such as a
semiconductor module is arranged to a heat radiation member for cooling. JP 2006-286676 A
describes that “a pressurizing jig is structured by overlapping an elastic member 8, a DC
10 positive-side wiring member 5 and a DC negative-side wiring member 6 in which currents flow
in opposite directions, a first fixing jig 1 is pressed by the pressurizing jig, a semiconductor
device 3 is pressed by the first fixing jig 1, and the semiconductor device 3 is fixed to a heat
radiation member 2 in a state where its heat radiation surfaces are made contact with respective
side wall surfaces 2c, 2d of the heat radiation member 2.”
15
SUMMARY OF THE INVENTION
[0003]
Each of drawings of FIG. 2 through FIG. 5 of JP 2006-286676 A indicates a
structure in which a plurality of power modules connected in parallel is mounted on a heat
20 radiation member. Specifically, when a plurality of power modules is connected in parallel to
form a power conversion device, it is preferable that plurality of power modules be electrically
closely arranged. However, when power modules are closely arranged, heat density between
power modules increases, resulting in need of a larger cooler. Consequently, prioritization of an
electrically preferable arrangement contradicts a preferable shape of a cooler, disadvantageously
25 making an electrically ideal arrangement be disturbed by the above larger cooler. In JP 2006-
286676 A, although power modules connected in parallel are made contact with a heat radiating
plate by a fixing jig and an elastic member is provided to the fixing jig, increase of heat density
- 3 -
between power modules may result in failure of efficient cooling. The invention aims to
provide a cooling structure of a heating element and a power conversion device capable of
efficiently cooling a plurality of power modules in a case where the power modules are provided
on a heat radiation member.
[5 0004]
To achieve the above object, for example, a cooling structure of a heating element
includes: a plurality of heating elements each having opposing two surfaces, at least one of the
two surfaces being a cooling surface; and a heat receiving block having a plurality of insertion
openings for inserting therein respective the plurality of heating elements, wherein an area in
10 which the plurality of insertion openings is not formed of the heat receiving block includes a
unshared cooling portion configured to receive heat from the cooling surface of corresponding
one of the plurality of heating elements, and a shared cooling portion sandwiched between
corresponding adjacent two of the plurality of insertion openings, the shared cooling portion
being configured to receive heat from corresponding adjacent two of the plurality of heating
15 elements, and wherein an amount of heat in the shared cooling portion, the heat being received
from the corresponding adjacent two of the plurality of heating elements, is larger than an
amount of heat in the unshared cooling portion, the heat being received from the corresponding
one of the plurality of heating elements.
[0005]
20 A cooling structure of a heating element and a power conversion device are
provided capable of efficiently cooling a plurality of power modules in a case where the power
modules are provided on a heat radiation member. Objects, configurations and effects other
than those described above will be elucidated by the ensuing description of embodiments.
25 BRIEF DESCRIPTION OF THE DRAWINGS
[0006]
FIG. 1 is a circuit diagram of a power conversion device according to the present
embodiment;
FIG. 2 is a circuit diagram of a converter of the power conversion device;
30 FIG. 3 is a circuit diagram of an inverter of the power conversion device;
FIG. 4 is a circuit diagram of a chopper of the power conversion device;
FIG. 5A is an external view of a power module;
FIG. 5B is a circuit diagram of the power module;
FIG. 6A illustrates an exploded perspective view of a cooler of the embodiment;
- 4 -
FIG. 6B is a perspective view of the cooler of the embodiment;
FIG. 7 is a perspective view in a state where the cooler of FIG. 6B is inserted in a
power unit;
FIG. 8 is an A-A’ cross-sectional view of the cooler illustrated in FIG. 7;
FIG. 9 is a cross-sectional view taken by a line B-B’ of FIG. 7 that is a cross5 -
section of a shared cooling portion;
FIG. 10 is a cross-sectional view taken along a line C-C’ of FIG. 7 that is a crosssection
of a unshared cooling portion;
FIG. 11A is an exploded perspective view of a basic converter unit;
10 FIG. 11B is a perspective view of the basic converter unit;
FIG. 12 is an appearance perspective view of a power conversion device
configured by arranging a plurality of basic converter units;
FIG. 13 is a perspective view of a cooler in a case where the diameter of heat
pipes provided in the shared cooling portion is changed;
15 FIG. 14 is a perspective view of the cooler in a case where the number of heat
pipes is changed;
FIG. 15 is a perspective view of the cooler in a case where arrangement of heat
pipes is changed;
FIG. 16 is a perspective view of the cooler in a case where the number of power
20 modules arranged in the cooler is changed;
FIG. 17A is a perspective view of a heat receiving spacer;
FIG. 17B is a perspective view of a heat receiving spacer;
FIG. 18 illustrates a state where the heat receiving spacers are attached to the
power module;
25 FIG. 19 illustrates an enlarged plan view of a B portion surrounded by a broken
line in FIG. 18;
FIG. 20 illustrates an enlarged diagram of a main part (end) on an A-A’ crosssection
in FIG. 18;
FIG. 21A illustrates a state before the power module is installed in a cooler as
30 viewed from an x-axis direction;
FIG. 21B illustrates a state where the power module is installed in the cooler as
viewed from an x-axis direction; and
FIG. 22 is a cross-sectional view of a heat pipe having a powder wick structure.
- 5 -
DESCRIPTION OF EMBODIMENTS

[0007]
A configuration of a power conversion device 100 according to an embodiment of
the invention will be described as 5 s follows.
[0008]
FIG. 1 is a circuit diagram of the power conversion device 100 according to the
embodiment.
[0009]
10 As illustrated in FIG. 1, to the power conversion device 100, alternating current
(AC) power adjusted to be an appropriate voltage is supplied from a power reception point 107
of a power system via a transformer 105. The supplied AC power is input to a converter 102,
and converted into direct current (DC) power. The DC power is input to an inverter 103, and
converted into AC power. The AC power is consumed by a three-phase AC load 108.
15 [0010]
On the other hand, when no power is supplied to the converter 102 due to failure
of the power system or the like, a higher rank control circuit 109 detects the failure and make a
chopper 104 operate. DC power input to the chopper 104 from a storage battery 106 is adjusted
to be an appropriate power by the chopper 104, and input to the inverter 103. The DC power
20 input to the inverter 103 is converted into AC power, and consumed by the three-phase AC load
108.
[0011]
The above operations are adjusted by determining a desired operation by the
higher rank control circuit 109 and by transmitting a command signal 110C to the converter 102,
25 a command signal 110I to the inverter 103, and a command signal 110X to the chopper 104 from
the higher rank control circuit 109. The converter 102, the inverter 103, and the chopper 104
generate heat to increase their temperatures during their operations. To suppress the
temperature increase, cooling air 111 generated by a cooling fan 101 (air blower) is sent for
cooling. Among the electric system having the above configuration, the cooling fan 101, the
30 converter 102, the inverter 103, the chopper 104, the higher rank control circuit 109, etc. are
housed in the power conversion device 100 of the embodiment. A filter circuit may be arranged
as needed between the converter 102 and the transformer 105 or between the inverter 103 and
the AC load 108.
[0012]
- 6 -
FIG. 2 is a circuit diagram of the converter 102 of the power conversion device
100, FIG. 3 is a circuit diagram of the inverter 103 of the power conversion device 100, and FIG.
4 is a circuit diagram of the chopper 104 of the power conversion device 100. Hereinafter, with
reference to FIGS. 2 to 4, circuits of respective the converter 102, the inverter 103, and the
chopper 104 will be describe5 d.
[0013]
The converter 102 illustrated in FIG. 2 includes legs 203 (203R, 203S, 203T) each
includes a plurality of semiconductor elements that are a switching element 204 (for example,
204RH, 204RL) and a diode element 205 (for example, 205RH, 205RL). Hereinafter, the leg
10 203, the switching element 204, and the diode element 205 are used collectively as representing
the entirety of respective components.
[0014]
Both ends of the leg 203 are connected to a capacitor 201. An upper arm of the
leg 203R includes a switching element 204RH and a reflux diode element 205RH, and a lower
15 arm of the leg 203R includes a switching element 204RL and a reflux diode element 205RL.
Likewise, an upper arm of the leg 203S includes a switching element 204SH and a reflux diode
element 205SH, and a lower arm of the leg 203S includes a switching element 204SL and a
reflux diode element 205SL. An upper arm of the leg 203T includes a switching element
204TH and a reflux diode element 205TH, and a lower arm of the leg 203T includes a switching
20 element 204TL and a reflux diode element 205TL. A switching signal to each of the switching
element 204RH, 204RL, 204SH, 204SL, 204TH, and 204TL are controlled by a converter gate
controller 202 that is a lower rank controller.
[0015]
Note that, as the switching element of the embodiment, an element capable of
25 switching on/off of current can be used. For example, the switching element includes an
insulated gate bipolar transistor (IGBT) and a power metal oxide semiconductor field effect
transistor (MOSFET).
[0016]
The inverter 103 illustrated in FIG. 3 includes legs 203 (203U, 203V, 203W) each
30 including a plurality of semiconductor elements, and both ends of the leg 203 are connected to a
capacitor 301. An upper arm of the leg 203U includes a switching element 204UH and a reflux
diode element 205UH, and a lower arm of the leg 203U includes a switching element 204UL and
a reflux diode element 205UL. Likewise, an upper arm of the leg 203V includes a switching
element 204VH and a reflux diode element 205VH, and a lower arm of the leg 203V includes a
- 7 -
switching element 204VL and a reflux diode element 205VL. An upper arm of the leg 203W
includes a switching element 204WH and a reflux diode element 205WH, and a lower arm of the
leg 203W includes a switching element 204WL and a reflux diode element 205WL. A
switching signal to each of the switching element 204UH, 204UL, 204VH, 204VL, 204WH, and
204WL are controlled by an inverter gate controller 302 that is a lower rank controller5 .
[0017]
The chopper 104 illustrated in FIG. 4 includes a leg 203X including
semiconductor elements, and both ends of the leg 203X are connected to a capacitor 401. An
upper arm of the leg 203X includes a switching element 204XH and a reflux diode element
10 205XH. A lower arm of the leg 203X includes a switching element 204XL and a reflux diode
element 205XL. A connection point between the switching elements 204XH, 204XL are
connected to the storage battery 106 (see FIG. 1) via a reactor 403. A switching signal to each
of the switching elements 204XH, 204XL is controlled by a chopper gate controller 402 that is a
lower rank controller.
15 [0018]
An example of the chopper gate controller 402 will be described as an example of
control operation.
[0019]
A switching signal applied to the chopper 104 is applied via a step-up/step-down
20 switching circuit (not shown). The selection depends on magnitude relationship between a DC
voltage value between the converter 102 and the inverter 103 and an output voltage value of the
converter 102 (rectification function). When the output of the chopper 104 is larger than the
output voltage of the converter 102, a pulse width modulation (PWM) signal is transmitted to the
switching element 204XL, and when smaller, a PWM signal is transferred to the switching
25 element 204XH.
[0020]
When electric power of the storage battery 106 is discharged, the switching
element 204XL is made to be switched depending on a PWM signal. When the switching
element is turned on, energy is accumulated in the reactor 403. On the other hand, when the
30 switching element is turned off, the capacitor 401 is charged by the voltage, which is greater than
the voltage of the storage battery 106, applied by the voltage of the storage battery 106 and the
energy of the reactor 403 via the diode element 205XH connected to the switching element
204XH.
[0021]
- 8 -
When the storage battery 106 is charged, the switching element 204XH is made to
be switched depending on a PWM signal, and when the switching element 204XH is turned on,
the electric power of the capacitor 401 is charged in the storage battery 106 via the reactor 403.
When the switching element 204XH is in off state, the energy accumulated in the reactor 403 is
circulated via the diode element 205XL connected to the switching element 204XL. Th5 e
operations enable the storage battery 106 to be charged and discharged.
[0022]
Note that although in a typical power conversion device, the capacitors are
arranged collectively in some cases, the capacitors 201, 301, 401 in the embodiment are
10 separately arranged from a standpoint of standardization of the configuration of a basic converter
unit 1100 (see FIG. 11B) to be described below. Specifically, the capacitors 201 and 301 are
further separated for each leg 203.
[0023]
Conduction and blocking of current by the switching element 204 and the diode
15 element 205 of the leg 203 illustrated in FIGS. 2 to 4 are performed to make the converter 102
execute conversion from AC to DC, and make the inverter 103 execute conversion from DC to
AC. During conduction, a loss occurs due to resistance embedded in the switching element 204
and the diode element 205. A loss also occurs when switching is performed from conduction
state to blocking state. Thus, the operation of the power conversion device 100 involves heat
20 generation.

[0024]
Next, a power module 500 (heating element, semiconductor device for power
conversion device) used in the embodiment will be described with reference to an appearance
25 view of FIG. 5A and circuit diagram of FIG. 5B.
[0025]
In FIG. 5A, the power module 500 includes a body part 710 having a substantially
rectangular parallelepiped shape, a flange unit 720 having a substantially a rectangular
parallelepiped shape formed to extend a side surface of the body part 710, and a terminal unit
30 730 including a plurality of terminals protruded from the surface opposing the body part 710 of
the flange unit 720. The terminals structuring the terminal unit 730 are ,as illustrated in FIG.
5B, a P terminal 704P, an N terminal 704N, an AC terminal 704AC, and gate terminals 701.
[0026]
In FIG. 5B, the power module 500 includes switching elements 204MH, 204ML
- 9 -
and diode elements 205MH, 205ML mounted on an insulator 753 (not shown). The pair of the
semiconductor elements are connected to form a leg 203 (for example, see FIG. 2). In addition,
to the insulator 753 (not shown), the P terminal 704P (DC positive terminal), the N terminal
704N (DC negative terminal), the AC terminal 704AC (AC terminal), and the gate terminals 701
for controlling on and off of the switching elements are attache5 d.
[0027]
Returning to FIG. 5A, on a surface 760A of the body part 710, a number of pin
fins 762A (not less than about 200 in total), which are projections having a fine columnar shape,
are protruded. Furthermore, the same number of pin fins 762B are formed also on another
10 surface 760B opposing the surface 760A of the body part 710. Hereinafter, the pin fins 762A,
762B are simply referred to as “pin fins 762” collectively in some cases. Furthermore, the
surfaces 760A, 760B are called “cooling surfaces”. The thickness of the body part 710 except
the pin fins 762, that is the distance between the cooling surfaces 760A, 760B shall be “d1”.
[0028]
15 Note that although the embodiment of the invention may include a mode having
no pin fin on the cooling surfaces 760A, 760B, and may include a case where a cooling surface
exists only on one surface (not on both surfaces), the power module 500 provided with the pinfins
on the both surfaces will be described as an example in the following example.
[0029]
20 When the above semiconductor elements operate, electrical conduction is made
with an external device via the terminal unit 730 while heat is discharged via the cooling surfaces
760A, 760B. That is, the terminal unit 730 is formed on one side surface adjacent to the
cooling surfaces 760A, 760B, and is electrically insulated from the cooling surfaces 760A, 760B,
so that heat transport route and electrical route are independent.
25 [0030]
Note that, the power module of the example is not necessarily the double-sided
cooling power module and needs to have only at least one cooling surface, and it is not necessary
that pin fins are provided on the cooling surface.

30 [0031]
Next, a cooler in the embodiment will be described with reference to FIGS. 6A to
10.
[0032]
FIG. 6A illustrates an exploded perspective view of a cooler 600 of the
- 10 -
embodiment.
[0033]
The cooler 600 includes a heat receiving block 601, heat pipes 602, and a heat
radiating fin 603.
[5 0034]
The heat receiving block 601 is formed of a metal having a relatively high
thermal conductivity such as aluminum or copper. Insertion openings 604 for inserting therein
respective one ends of the heat pipes 602 are formed in the heat receiving block 601, and the heat
receiving block 601 and the heat pipes 602 are connected by inserting the one ends of the heat
10 pipes 602 into respective the insertion openings 604.
[0035]
The heat pipe 602 has only to be a heat transfer member, and may be another
constituent element other than the heat pipe 602. Note that in the following example,
description will be made in which the heat pipe 602 is an example of the heat transfer member.
15 [0036]
The heat radiating fin 603 is formed by laminating heat radiating plates in a z-axis
direction, and insertion openings 605 for inserting therein respective the other ends of the heat
pipes 602 are formed in each of the heat radiating plates, and the heat radiating fin 603 and heat
pipes 602 are connected by inserting the other one ends of the heat pipes 602 into respective the
20 insertion openings 605.
[0037]
Furthermore, the heat receiving block 601 is provided with power module
insertion openings 606 having a shape to match the power module. Furthermore, the insertion
opening 606 has a heat receiving surface 607 to be made contact with the following power
25 module.
[0038]
FIG. 6B is a perspective view of the cooler 600 of the embodiment. FIG. 6B is a
perspective view of the cooler 600 in a state where the heat pipes 602 illustrated in FIG. 6A are
inserted into the insertion openings formed in the heat receiving block 601 and the heat radiating
30 fin 603.
[0039]
In the example, a cooling air 606 is sent from -y direction.
[0040]
FIG. 7 is a perspective view in a state where the power unit 700 is inserted into
- 11 -
the cooler 600 of FIG. 6B. The power module insertion opening 606 is provided to match the
shape of the power module 700, making it possible to make the heat receiving surface 607 be
made contact with the cooling surface (yz-plane) of the power module.
[0041]
FIG. 8 is an A-A’ cross-sectional view of the cooler 600 illustrated in FIG. 5 . 7.
[0042]
Heat generated by the power module 700 is first transferred to the heat receiving
block 601, and transferred to the heat radiating fin 603 from the heat receiving block 601 via the
heat pipes 602. The heat is finally radiated by the cooling air 606 flowing between heat
10 radiating fins.
[0043]
The heat pipes 602 has a hollow tube structure, and liquid called operating liquid
such as pure water is sealed in the hollow. For example, when an end of the heat pipe 602 is
made contact with a heating element, the end of the heat pipe 602 receives heat, and the heat is
15 transferred to the operating fluid inside the heat pipe 602 to make the operating fluid vaporize
and evaporate. The evaporated operating liquid is moved to the other end of the heat pipe 602
and cooled to be liquefied at the other end. The liquefied operating liquid moves to the end of
the heat pipe and evaporated again. The heat pipe is a member that transports heat by the above
cycle.
20 [0044]
Incidentally, operating liquid, which is liquid, has a high fluidity so that its
moving direction basically follows the direction of gravitational force. Consequently, when the
heat pipe is used, a heat generating portion is placed on the lower side and a cooling portion is
placed on the upper side in the direction of gravitational force typically. In the heat pipe 602
25 used in the cooler 600 in the embodiment, a porous layer formed of fine powder called powder
wick is formed on its inner wall. Note that the wick may be, besides powder wick, a grove
wick or a wire fabric wick.
[0045]
FIG. 22 illustrates a cross-sectional view of the heat pipe 602 having a powder
30 wick structure. A powder wick 2201 is formed on the inner wall surface of the heat pipe 602 by
making fine particles be sintered along the inner wall surface of the heat pipe. Operating liquid
2202 is housed in the heat pipe 602, and the operating liquid 2202 penetrates into voids formed
in the powder wick 2201 and moves in the direction opposite to the direction of gravitational
force by a capillary force 2203 acting more than gravitational force 2204. That is, the powder
- 12 -
wick has a function of absorbing water like capillary tube. The moved operating liquid 2202
receives heat of the heat receiving block 601 to which the heat pipe 602 is attached to become
steam 2205. Then, the steam 2205 moves in the direction of the heat radiating fin 603, which is
the direction of gravitational force, and cooled by the heat radiating fin 603 to be liquefied to
become the operating liquid 2202. In this manner, the operating liquid 2202 repeats the a5 bove
circulation. This mechanism allows the cooler to have a configuration in which the heat
generating portion 802 is placed on the upper side and the cooling portion 803 is placed on the
lower side with respect to gravitational force.
[0046]
10 While heat transport via the heat pipes 602 is performed by the above mechanism,
cooling is performed by heat radiation routes 1 to 4 passing the respective heat receiving surfaces
as illustrated in FIG. 8. A shared cooling portion 800 that shares heat of the heat radiation route
2 and the radiation route 3 sandwiched by two power modules receives a large amount of heat as
compared with unshared cooling portions 801 formed by respective the heat radiation route 1
15 and the heat radiation route 4 that shear only heat from corresponding one heat receiving surface.
[0047]
FIG. 9 is a B-B’ cross-sectional view in FIG. 7 that is a cross-section of the shared
cooling portion 800.
[0048]
20 Four heat pipes are arranged in a y-axis direction in the shared cooling portion
800. One power module (not shown) is arranged on each of the front side and back side with
respect to the paper via the shared cooling portion 800, and the heat generated from the power
modules is transferred to the shared cooling portion 800. Heat from the power module
provided on the back side with respect to the paper is transmitted to the shared cooling portion
25 800 via heat radiation routes 901, and heat from the power module provided on the front side
with respect to the paper is transmitted to the shared cooling portion 800 via heat radiation routes
902. The transferred heat is transferred in the axis direction and transferred to the heat pipes
602 and the cooling portion 803 as illustrated in the drawing. The amount of heat passing the
shared cooling portion 800 is about double the amount of heat passing unshared cooling portions
30 801, but the number of the heat pipes in the shared cooling portion is made double, making it
possible to make the heat amounts transported by respective heat pipes substantially equal.
[0049]
FIG. 10 is a C-C’ cross-sectional view in FIG. 7 that is a cross-section of the
unshared cooling portion 801.
- 13 -
[0050]
Two heat pipes are arranged in the unshared cooling portion 801. The two
power modules (not shown) are arranged on the back side of the paper via the unshared cooling
portion 801, and the heat generated from the power modules is transferred to the unshared
cooling 5 portion 801.
[0051]
It is preferable that the heat pipes in the shared cooling portion 800 be arranged in
a straight manner and in parallel with the cooling air direction. The arrangement in the straight
manner makes it possible to minimize the distance between the power modules.
10
[0052]
Next, a basic converter unit in the embodiment will be described with reference to
FIGS. 16 to 17.
[0053]
15 FIG. 11A is an exploded perspective view of a basic converter unit 1100.
[0054]
The P terminal 704P, the N terminal 704N, the AC terminal 704AC, which are
electric terminals of the power module 500 described in FIG. 5, are connected to bus bars. The
bus bars include a bus bar (P) 1101, a bus bar (AC) 1102, an intermediate bus bar 1104, and a
20 bus bar (N) 1103. The gate terminal 701 that is an electric terminal is connected to the gate
driver substrate 1104. Furthermore, each of a positive electrode terminal and a negative
electrode terminal of a capacitor 1105 is connected to the corresponding bus bar.
[0055]
In this manner, it is preferable that the bus bar for electrically connecting the
25 capacitor 1105 and the power module 500 be made short in a y-axis direction and small in its
bending degree as far as possible.
[0056]
Incidentally, it is preferable to make a space where no component is arranged
(hereinafter, referred to as dead space) small when a power conversion device is configured by
30 combining components having different functions in this manner, because increase of dead space
leads to growing in size of the power conversion device with respective to its functions. From
the viewpoint, the power module 600 and the cooler 600 to which the power module 600 is
attached, and the capacitor 1105 are connected in the same direction with respect to the bus bar
1106. Supposing that one of them is arranged in the opposite direction with respect to the bus
- 14 -
bar 1106, a dead space appears. For example, when the power module 500 and the cooler 600
are provided in +Z direction with respect to the bus bar 1106, a dead space appears at a side (yaxis
direction in FIG. 16) of the capacitor. In contrast, when the capacitor 1105 is provided in
+Z direction with respect to the bus bar 1106, a dead space appears at a side of the cooler (y-axis
direction). In the embodiment, the above configuration of the cooler 600 makes 5 s it possible to
prevent presence of such a dead space.
[0057]
FIG. 11B is a perspective view of the basic converter unit 1100.
[0058]
10 In the embodiment, cooling air is sent in -y direction in the basic converter unit
1100, that is, toward the cooler 600 from the capacitor 1105 and the bus bar 1106.

[0059]
15 It is preferable that the capacitor 1105 to be used be a small electrolytic capacitor
having a high capacity density and a large capacity. This makes it possible to provide the
capacitance to keep the functions of the power conversion device with a small number of small
capacitors to provide a small power conversion device with a simple manufacturing process of
connecting electric terminal with bus bar.
20 [0060]
Such a capacitor 1105 seals therein electrolysis solution having a high flowability
to keep the capacitance that is its function. The capacitor 1105 is equipped with a mechanism
called a safety valve 1107 on a surface same as the surface on which the electric terminals are
arranged. The safety valve 1107 suppresses increase in inner pressure by opening a partition
25 between the inside and the outside of the capacitor 1105 when inner pressure of the capacitor
1105 increases to more than a predetermined level. Most preferably, the safety valve 1107 is
arranged such that the surface on which the safety valve is arranged is oriented in the upper
direction (z-axis direction). This makes it possible to safely use the capacitor 1105 having a
high capacity density.
30 [0061]
The arrangement of the capacitor 1105 is determined on the basis of the above
reasons, and the above configuration makes it possible to prevent presence of a dead space.
< Appearance Configuration of Power Conversion Device>
[0062]
- 15 -
FIG. 12 is a perspective external view of a power conversion device 1200 formed
by arranging a plurality of basic converter units.
[0063]
In the power conversion device 1200, a converter 1203, an inverter 1202, and a
chopper 1201 are laterally arranged. The converter 1203 includes basic converter 5 r units 1204
corresponding to the three legs 203R, 203S, and 203T illustrated in FIG. 2. The inverter 1202
includes basic converter units 1204 corresponding to the three legs 203U, 203V, and 203W
illustrated in FIG. 3. The chopper 1201 includes one basic converter unit 1204. In this regard,
the converter 1203, the inverter 1202, and the chopper 1201 may be arranged in an order
10 different from that in the embodiment, and may be arranged in any order among the converter
1203, the inverter 1202, and the chopper 1201. Cooling air is sent from -y direction in the order
from capacitors 1605 and 1606 to the coolers 600. This provides the advantage of not reducing
cooling effect between basic converter units 1204 even when the basic converter units 1204 are
laterally and densely arranged. Furthermore, when temperatures of semiconductor elements of
15 respective the converter 1203, the inverter 1202, and the chopper 1201 are different, wind
velocity of cooling air or the like may be changed.
[0064]
As described above, in the embodiment, the cooler includes unshared cooling
portions that receive heat from one cooling surface, and a shared cooling portion sandwiched
20 between two cooling surfaces and receives heat from the two cooling surfaces. Heat pipes are
arranged so that cooling capability of the shared cooling portion becomes higher than the cooling
capability of the unshared cooling portions, allowing the shared cooling portion to provide a
desired cooling with a volume equivalent to those of the unshared cooling portions.
[0065]
25 Furthermore, the embodiment includes the heat pipe using powder wick, which
makes it possible to reduce a dead space when forming the power conversion device, making it
possible to downsize the power conversion device.

[0066]
30 The invention is not limited to the above embodiment, and various modifications
can be made, for example, as described below.
(1) Size of Cross-Sectional Area in xy-Plane of Heat Pipe
[0067]
FIG. 13 is a perspective view of a cooler in a case where the diameter of the heat
- 16 -
pipe provided in the shared cooling portion 800 is changed.
[0068]
Making the cross-sectional area in the xy-plane of heat pipes 1301 provided in the
shared cooling portion 800 larger than the cross-sectional area in the xy-plane of the heat pipes
1300 provided in the unshared cooling portion 801 makes it possible to increase a defined 5 d value
of heat amount capable of being transported. This makes it possible to reduce the total number
of heat pipes and the total number of components, advantageously facilitating management of
members. Other configuration is similar to that in FIG. 6B, so that description thereof will be
omitted.
10 (2) The Number of Heat Pipes
[0069]
FIG. 14 is a perspective view of the cooler 600 in a case where the number of the
heat pipes is changed.
[0070]
15 The number of heat pipes 1401 provided in the shared cooling portion 800 can be
made larger than the number of heat pipes 1400 provided in unshared cooling portion 801.
Making the diameter of the heat pipes 1401 small makes it possible to increase the number of the
heat pipes 1401 to be arranged in the same volume. This case allows heat to be widely spread
spatially as compared with the case where the number of heat pipes is small, which improves
20 cooling efficiency, making it possible to further downsize the cooler.
(3) Arrangement of Heat Pipes
[0071]
FIG. 15 is a perspective view of the cooler 600 in a case where arrangement of
heat pipes is changed.
25 [0072]
Making the diameter of heat pipes 1501 provided in the shared cooling portion
800 small makes it possible to arrange the heat pipes in two or more rows in the same volume.
In this case, a desired cooling function can be provided by making total heat amount to be
transported by the heat pipes in the shared cooling portion 800 substantially be double of heat
30 amount to be transported in the unshared cooling portion 801. Furthermore, the heat pipes 1501
are used having a diameter smaller than that of the heat pipes 1500 provided in the unshared
cooling portion 801, easily enabling the optimum arrangement, for example, in which heat pipes
are densely arranged to a portion of a double-sided cooled power module where heat is
specifically generated and no heat pipe is arranged at a portion other than the portion as
- 17 -
compared with a case of using heat pipes having a large diameter. This enables more efficient
cooling.
(4) Thickness of Shared cooling Portion and Unshared cooling Portion
[0073]
It is also possible to make the thickness of the shared cooling portion larger 5 than
the thickness of the unshared cooling portion in an x-axis direction. This structure makes it
possible to make the area of heat radiating fin in the shared cooling portion larger than the area
of heat radiating fin in the unshared cooling portion, making it possible to make thermal
resistance of heat radiation route via the shared cooling portion lower than thermal resistance of
10 heat radiation route via the unshared cooling portion to enhance heat radiation efficiency.
(5) The Number of Power Modules
[0074]
FIG. 16 is a perspective view of the cooler in a case where the number of power
modules 500 arranged in the cooler 600 is changed.
15 [0075]
In the modification, three insertion openings 605 are provided, and two shared
cooling portions 800 are provided. Note that the number of the insertion openings 605 may be
three or more. In this case, like FIGS. 6A, 6B, although the number of heat pipes provided in
the shared cooling portion 800 is larger than the number of heat pipes provided for the unshared
20 cooling portion 801, any of the modifications as illustrated above (1) to (3) and the modification
as illustrated above (4) may be applied.
(6) Arrangement of Power Modules
[0076]
Although the example is illustrated above in which the plurality of insertion
25 openings 605 is arranged in an x-axis direction, a plurality of insertion openings 605 may be
arranged also in a y-axis direction when a cooling surface of the cooler 600 exists also in the xzplane.
In this case, a shared cooling portion 800 is formed between insertion openings 605
arranged side-by-side in a y-axis direction, and unshared cooling portions 801 are also formed.
To the shared cooling portion 800 and the unshared cooling portions 801 in a y-axis direction,
30 any of the above embodiment and modifications (1) to (5) can be applied.
(7) Electrolytic Capacitor of Substrate Self-Standing Type
[0077]
The capacitor to be used may be a capacitor having no safety valve. A capacitor
having no safety valve generally has a small capacitance per volume, but a capacitor bank having
- 18 -
a large capacitance can be formed by connecting a plurality of capacitors in parallel. This
makes it possible to reverse the top and bottom of the basic converter unit, allowing more free
installation.

[5 0078]
The following mode can be employed for the power module 500 to be installed in
the above cooler 600. Note that in the following example, although an example is described in
which the power module has two opposing surfaces that are cooling surfaces, and the cooling
surfaces have pin fins, the power module needs to have only at least one cooling surface, and
10 may have no pin fin.
[0079]
FIG. 17A and FIG. 17B are each a perspective view of a heat receiving spacer.
[0080]
A pair of heat receiving spacers 630A, 630B illustrated in FIG. 17A and FIG. 17B
15 are brought into contact with the cooling surfaces 760A, 760B of the power module 500,
respectively. The heat receiving spacer 630A includes a heat receiving part 631A (heat
receiving plate) having a substantially rectangular plate shape, and a pair of space securing parts
632A having a substantially rectangular parallelepiped shape protruded toward the heat receiving
spacer 630B from the both ends of the heat receiving part 631A. Furthermore, a number of
20 through holes 633A (holes) having a columnar shape are provided in the heat receiving part
631A. The through hole 633A are formed at positions to oppose the respective pin fins 762A of
the cooling surface 760A, and have a diameter slightly larger than the diameter of the pin fins
762A. It is ideal that the though holes 633A are fitted into the pin fins 762A with no space if
possible, but the diameter and positions of the pin fins 762A involve a slight manufacturing
25 error, so that the diameter of the through holes 633A is increased to a level so that the
manufacturing error can be allowed. Note that it is not limited that one pin fin 762A is inserted
into one through hole 633A, and a plurality of pin fins 762A may be inserted into a through hole
633. Furthermore, the shape of the though hole 633 is not limited to a columnar shape and may
be any shape such as a square pole shape as long as the pin fin can be inserted. In this manner,
30 by making the pin fins be inserted into the through holes, a state is kept in which the heat
receiving spacers 630A, 630B are assembled while being brought into contact with the power
module 500 even when the power unit is installed such that gravitational force is applied thereto
in -y direction. Note that, in the case of a mode where no pin fin exists, there is no portion to be
engaged, so that the heat receiving spacers 630A, 630B may be unfortunately laterally slid with
- 19 -
respect to the power module 500. In this case, the flange unit 720 of the power module 500 and
a cooler 610 to be described below are fixed by, for example, screw coupling to prevent the slide.
[0081]
The heat receiving spacer 630B includes a heat receiving part 631B having a
substantially rectangular plate shape, and a pair of space securing parts 632B having 5 a
substantially rectangular parallelepiped shape protruded toward the heat receiving spacer 630A
from the both ends of the heat receiving part 631B. The heat receiving spacer 630B have a
vertically symmetrical shape as a whole with respect to the heat receiving spacer 630A, but in
the heat receiving part 631B, through holes 633B are formed at positions to oppose the
10 respective pin fins 762B protruded from the cooling surface 760B of the power module 500.
Similarly, the heat receiving spacer 630A includes a heat receiving part 631A having a
substantially rectangular plate shape, and a pair of space securing parts 632A having a
substantially rectangular parallelepiped shape protruded toward the heat receiving spacer 630B
from the both ends of the heat receiving part 631A. The heat receiving spacer 630A includes a
15 heat receiving part 631A having a substantially rectangular plate shape, and a pair of space
securing parts 632A having a substantially rectangular parallelepiped shape protruded toward the
heat receiving spacer 630B from the both ends of the heat receiving part 631A. The heat
receiving spacer 630B have a vertically symmetrical shape as a whole with respect to the heat
receiving spacer 630A.
20 [0082]
Herein, it is preferable that the heat receiving spacers 630A, 630B be formed of a
high heat conduction metal such as aluminum or copper from the viewpoint of heat radiation
properties, but in the case where insulation is needed between the power module 500 the cooler
610, a resin or a ceramic may be used as the heat receiving spacers 630A, 630B.
25 [0083]
Furthermore, the space securing parts 632A, 632B do not necessarily have to be
provided at both ends in an x-axis direction in the xz-plane of the heat receiving spacer, and only
need to be provided at positions that allow a distance between the heat receiving spacers to be
secured when assembled to the power module 500.
30 [0084]
FIG. 18 illustrates a state where the heat receiving spacers 630A, 630B are
attached to the power module 500.
[0085]
When the heat receiving spacers 630A, 630B are attached to the power module
- 20 -
500, heat conduction grease is sufficiently coated on the cooling surfaces 760A, 760B, and the
space securing portions 632A, 632B are brought into contact with each other while aligning the
positions of the through holes 633A, 633B to respective the pin fins 762. Herein, an elastic
member 801 is provided on a contact surface where the space securing portions 632A, 632B are
brought into contact with each other. Furthermore, although the body part 710 is exposed 5 in its
end face 710a, a large portion of the cooling surfaces 760A, 760B is covered with the heat
receiving spacers 630A, 630B. Note that a heat conduction sheet may be used instead of the
heat conduction grease. Such a configuration makes it possible to prevent a pressing force from
being applied on the cooling surface even when the power module 500 is inserted into the
10 insertion opening 605, and receives a pressing force from the heat receiving surface 607.
[0086]
FIG. 19 illustrates an enlarged plan view of a B portion surrounded by a broken
line of FIG. 18.
[0087]
15 As described above, the diameter of the through hole 633A is slightly larger than
the diameter of the pin fin 762A, so that the pin fin 762A is loosely inserted into the through hole
633A with a gap 635 being formed between with the through hole 633A. At the time, the heat
conduction grease coated on the pin fin 762A penetrates in the gap 635 to be pushed, so that the
gap 635 is filed with the heat conduction grease without a gap.
20 [0088]
FIG. 20 illustrates an enlarged diagram of a main part (end) on an A-A’ crosssection
in FIG. 18.
[0089]
When the space securing parts 632A, 632B are brought into contact with each
25 other, the heat receiving parts 631A, 631B face each other at a predetermined distance. This
distance is defined as d2. The heat receiving spacers 630A, 630B are formed so that the
distance d2 becomes slightly longer than the thickness d1 of the body part 710 of the power
module 500. As a result, gaps 637A, 637B are formed between the heat receiving part 631A
and the body part 710, and between the heat receiving part 631B and the body part 710,
30 respectively. The gaps 637A, 637B make it possible to prevent a pressing force from being
applied on the power module 500 even when a pressing force F that is an external force is
applied to the heat receiving parts 631A, 631B. Since the power module 500 has looseness
with respect to the heat receiving spacers 630A, 630B, widths of the gaps 637A, 637B are not
necessarily equal to each other.
- 21 -
[0090]
When the space securing parts 632A, 632B are brought into contact with each
other, the heat conducting grease coated on each pin fin 762 also penetrates to be pushed into the
gaps 637A, 637B and thus the gaps 637A, 637B are also filled with the heat conducting grease
with no gap. Herein, a thickness of the body part 710 inclusive of a distance from a 5 tip of the
pin fin 762A to a tip of the pin fin 762B shall be d4 and the entire width obtained when the heat
receiving spacers 630A, 630B are brought into contact with each other shall be d5. At this
time, the heat receiving spacers 630A, 630B are formed so that the width d5 is slightly greater
than the thickness d4. Consequently, gaps 639A, 639B are formed between an upper surface of
10 the heat receiving spacer 630A and the tip of the pin fin 762A, and between a lower surface of
the heat receiving spacer 630B and the tip of the pin fin 762B in the illustration, respectively.
As described above, the gaps 639A, 639B give the power module 500 looseness with respective
to the heat receiving spacers 630A, 630B, respectively so that widths of the gaps 637A, 637B are
not necessarily equal to each other.
15 [0091]
When the heat receiving spacers 630A, 630B are attached to a cooler 610 (details
will be described later), a pressing force F as indicated by hatched arrows is applied. This
pressing force F is applied to the portion at which the space securing parts 632A, 632B is
brought into contact with each other. In the embodiment, the gaps 637A, 637B are formed
20 between the body part 710 and the heat receiving spacers 630A, 630B, and the gaps 639A, 639B
are formed at a portion of each of the tips of the pin fins 762A, 762B respectively,
making it possible to prevent the pressing force from being applied on the power module 500 via
the in fins 762A, 762B. This makes it possible to prevent breakage of the power module 500
before something happens. Furthermore, the elastic member 801 is attached to the contact
25 portion between the space securing parts 632A, 632B. A resin plate having elasticity can be
used for the elastic member 801 as an elastic member, but a metal spring member or the like may
be used alternatively. This varies, within an expansion and contraction range of the elastic
member, the sizes of the distance d2 between the surfaces of the heat receiving spacers opposing
cooling surfaces and the distance d5 between the front surfaces of the heat receiving spacers.
30 When the elastic member is compressed, a repulsive force f depending on compression amount
generates, generating forces to push the heat receiving spacers in the upper and lower directions.
[0092]
FIG. 21A illustrates a state before the power module 500 is installed into the
cooler 610 as viewed from an x-axis direction.
- 22 -
[0093]
As illustrated in FIG. 21A, the power module 500 is sandwiched by the heat
receiving spacers 630A, 630B. The elastic member 801 is provided at the contact portion
between the heat receiving spacers 630A, 630B. The cooler 610 has a slot 611 for inserting
therein the power module, and having sizes H, W, and S in z, y, and z-axes directi5 ons,
respectively. When the power module 500 is inserted into the cooler 610, as illustrated in the
drawing, a pressing force F in a y-axis direction is applied to the heat receiving spacers 630A,
630B, and installed in the slot 611 while the sizes of d2 and d5 are changed.
[0094]
10 Specifically, under the situation where no pressing force F is applied on the heat
receiving spacers 630A, 630B (elastic member 801), the slot 611 is designed such that the size W
becomes smaller than the size d5. When the power module 500 is inserted in the slot 611, the
elastic member 801 is compressed via the heat receiving spacers 630A, 630B to make the size d5
be not less than the insertion hole size W of the cooler. The power module 500 is inserted in
15 the slot while the state is maintained. Upon sufficient insertion, the pressing force F to the heat
receiving spacers 630A, 630B (elastic member 801) is released.
[0095]
FIG. 21B illustrates a state before the power module 500 is installed in the cooler
610 as viewed from an x-axis direction. Upon insertion of the power module 500, a force to
20 make each of the heat receiving spacers 630A, 630B push a corresponding one of heat receiving
surfaces 612 of the cooler 610 is applied by a repulsive force N of the elastic member 801.
This force makes static frictional force act when the power module 500 is made to move in an x,
y, or z-axis direction, making it possible to fix the double-sided cooling power module.
Furthermore, making the heat receiving spacers 630A, 630B contact with the heat receiving
25 surfaces 612 by the repulsive force N makes it possible to efficiently transfer heat generated by
and transferred from the power module 500 to the cooler 610.
[0096]
It should be further understood by those skilled in the art that the foregoing
description has been made on embodiments of the invention and that various changes and
30 modifications may be made in the invention without departing from the spirit of the invention
and the scope of the appended claims.

WE CLAIM:
1. A cooling structure of a heating element comprising:
a plurality of heating elements each having opposing two surfaces, at least one of
the two surfaces being a cooling surface (760A, 760B); and
a heat receiving block (601) having a plurality of insertion openings (604, 605,
606) for inserting therein respective the plurality of heating elements, wherein
an area in which the plurality of insertion openings (604, 605, 606) is not formed
of the heat receiving block (601) includes
a unshared cooling (801) portion configured to receive heat from the cooling
surface (760A, 760B) of corresponding one of the plurality of heating elements, and
a shared cooling portion (800) sandwiched between corresponding adjacent two
of the plurality of insertion openings (604, 605, 606), the shared cooling portion (800) being
configured to receive heat from corresponding adjacent two of the plurality of heating elements,
and wherein
an amount of heat in the shared cooling portion (800), the heat being received
from the corresponding adjacent two of the plurality of heating elements, is larger than an
amount of heat in the unshared cooling portion (801), the heat being received from the
corresponding one of the plurality of heating elements.
2. The cooling structure of a heating element according to claim 1, wherein
a heat transfer member is provided in each of the shared cooling portion (800) and
the unshared cooling portion (801), and a heat amount transported by the heat transfer member
provided in the shared cooling portion (800) is larger than a heat amount transported by the heat
transfer member provided in the unshared cooling (801) portion.
3. The cooling structure of a heating element according to claim 1, wherein
the heating element is a power module (500, 606, 700), and the cooling structure
further comprising a heat radiating fin (603) provided in a direction opposite to an extending
direction in which a terminal of the power module (500, 606, 700) extends toward an external
side of a body of the power module (500, 606, 700), the heat radiating fin (603) being configured
to cool the heating element.
4. The cooling structure of a heating element according to claim 2, wherein
the heat transfer member has therein a wick structure and includes therein
operating liquid (2202), and the wick structure makes a capillary tube force (2203) acting on the
operating liquid (2202) act more than gravitational force.
5. The cooling structure of a heating element according to claim 1, wherein
- 24 -
the number of heat transfer members provided in the shared cooling portion (800)
is larger than the number of heat transfer members provided in the unshared cooling portion
(801).
6. The cooling structure of a heating element according to claim 1, wherein
an inner diameter of the heat transfer member provided in the shared cooling
portion (800) is larger than an inner diameter of the heat transfer member provided in the
unshared cooling portion (801).
7. A fixing structure of the heating element according to claim 1, comprising:
a pair of heat receiving plates provided to cover respective the two surfaces of the
heating element; and
an elastic member provided in an area in which the pair of heat receiving plates
face to each other, wherein
when the heating element and the pair of heat receiving plates are inserted in one
of the plurality of insertion openings (604, 605, 606), a pressing force to make the pair of the
heat receiving plates contact with respective inner wall surfaces of the one of the plurality of
insertion openings (604, 605, 606) is applied by the elastic member (801).
8. A power conversion device (100, 1200) wherein,
a capacitor (201, 301, 401, 1105, 1605) is connected to a bus bar (1104, 1106) to
which the cooling structure of a heating element according to claim 1 is connected, and
a body part of the capacitor (201, 301, 401, 1105, 1605) is provided on a side,
with respect to the bus bar (1104, 1106), of an area in which the cooling structure is provided.