U.S. patent application number 13/580263 was filed with the patent office on 2013-02-28 for rotating electric machine system.
This patent application is currently assigned to HITACHI AUTOMOTIVE SYSTEMS, LTD.. The applicant listed for this patent is Takeshi Matsuo. Invention is credited to Takeshi Matsuo.
Application Number | 20130049495 13/580263 |
Document ID | / |
Family ID | 44506348 |
Filed Date | 2013-02-28 |
United States Patent
Application |
20130049495 |
Kind Code |
A1 |
Matsuo; Takeshi |
February 28, 2013 |
ROTATING ELECTRIC MACHINE SYSTEM
Abstract
A rotating electric machine system includes: a rotating electric
machine including a stator and a rotor arranged with a gap to the
stator; a casing configured to hold the stator; an electric power
conversion apparatus held by the casing, and configured to drive
the rotating electric machine; and a first cooling flow path
arranged in a portion of the casing between the stator and the
electric power conversion apparatus, via which cooling medium is
caused to flow so as to cool the stator and the electric power
conversion apparatus. And: the electric power conversion apparatus
comprises a power module configured to include a power
semiconductor element therein; the power module comprises a heat
radiation fin; and the heat radiation fin is arranged to protrude
toward a cooling medium side via an opening formed between the
power module and the first cooling flow path.
Inventors: |
Matsuo; Takeshi;
(Hitachinaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Matsuo; Takeshi |
Hitachinaka-shi |
|
JP |
|
|
Assignee: |
HITACHI AUTOMOTIVE SYSTEMS,
LTD.
Hitachinaka-shi, Ibaraki
JP
|
Family ID: |
44506348 |
Appl. No.: |
13/580263 |
Filed: |
August 24, 2010 |
PCT Filed: |
August 24, 2010 |
PCT NO: |
PCT/JP2010/064279 |
371 Date: |
October 25, 2012 |
Current U.S.
Class: |
310/53 ; 310/59;
310/64 |
Current CPC
Class: |
G06F 16/178 20190101;
H02K 9/22 20130101; H02K 5/225 20130101; H02K 11/33 20160101; H02K
5/20 20130101; G06F 16/1844 20190101; G06F 16/13 20190101; H05K
7/20927 20130101; H02K 9/19 20130101; G06F 16/1748 20190101 |
Class at
Publication: |
310/53 ; 310/64;
310/59 |
International
Class: |
H02K 5/20 20060101
H02K005/20; H02K 9/00 20060101 H02K009/00; H02K 5/18 20060101
H02K005/18 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 26, 2010 |
JP |
2010-041233 |
Claims
1. A rotating electric machine system, comprising: a rotating
electric machine including a stator and a rotor arranged with a gap
to the stator; a casing configured to hold the stator; an electric
power conversion apparatus held by the casing, and configured to
drive the rotating electric machine; and a first cooling flow path
arranged in a portion of the casing between the stator and the
electric power conversion apparatus, via which cooling medium is
caused to flow so as to cool the stator and the electric power
conversion apparatus, wherein: the electric power conversion
apparatus comprises a power module configured to include a power
semiconductor element therein; the power module comprises a heat
radiation fin; and the heat radiation fin is arranged to protrude
toward a cooling medium side via an opening formed between the
power module and the first cooling flow path.
2. A rotating electric machine system according to claim 1, further
comprising: a second cooling flow path arranged in a portion of the
casing outside of the stator to extend along a direction of
rotation of the rotating electric machine, via which the cooling
medium flows, wherein: the second cooling flow path communicates
with the first cooling flow path such that the cooling medium cools
the stator after cooling the electric power conversion
apparatus.
3. A rotating electric machine system according to claim 2,
wherein: the first cooling flow path has a structure configured to
change a direction in which the cooling medium flows; and the
second cooling flow path communicates with the first cooling flow
path such that the cooling medium cools the stator after cooling
the electric power conversion apparatus and the second cooling flow
path has a greater cross-sectional area than a cross-sectional area
of the first cooling flow path at a communicating portion.
4. A rotating electric machine system according to claim 1,
wherein: the power module is configured to include power
semiconductor elements in two rows; and the first cooling flow path
is configured such that the cooling medium cools the power
semiconductor elements arranged in a first row, following which a
direction in which the cooling medium flows is changed, and the
cooling medium cools the other power semiconductor elements
arranged in a second row.
5. A rotating electric machine system according to claim 1, further
comprising: a temperature sensor arranged in a vicinity of the heat
radiation fin, wherein: cooling is controlled based upon
temperature data acquired by the temperature sensor.
6. An rotating electric machine system, comprising: a rotating
electric machine including a stator and a rotor configured to
rotate with a gap to the stator; an electric power conversion
apparatus held by a casing configured to hold the stator, and
configured to drive the rotating electric machine; a first cooling
flow path arranged at a portion of the casing between the stator
and the electric power conversion apparatus, via which cooling
medium is caused to flow so as to cool the electric power
conversion apparatus; and a second cooling flow path arranged in a
portion of the casing outside of the stator, and configured such
that the stator is cooled by the cooling medium that flows via the
second cooling flow path along a direction of rotation of the
rotating electric machine, wherein: the first cooling flow path has
a structure configured to change a direction in which the cooling
medium flows; and the second cooling flow path communicates with
the first cooling flow path such that the cooling medium cools the
stator after cooling the electric power conversion apparatus, and
the second cooling flow path has a greater cross-sectional area
than a cross-sectional area of the first cooling flow path at a
communicating portion.
7. A rotating electric machine system according to claim 6,
wherein: the electric power conversion apparatus comprises a power
module configured to include power semiconductor elements in two
rows; and the first cooling flow path is configured such that the
cooling medium cools the power semiconductor elements arranged in a
first row, following which a direction in which the cooling medium
flows is changed, and the cooling medium cools the other power
semiconductor elements arranged in a second row.
8. A rotating electric machine system according to claim 7,
wherein: a heatsink plate of the power module includes a heat
radiation fin; and the heat radiation fin is configured to protrude
toward a cooling medium side via an opening formed between the
power module and the first cooling path.
9. A rotating electric machine system according to claim 8, further
comprising: a temperature sensor in a vicinity of the heat
radiation fin; and cooling is controlled based upon temperature
data acquired by the temperature sensor.
Description
TECHNICAL FIELD
[0001] The present invention relates to a rotating electric machine
(rotating electric machine system) having a structure
monolithically integrated with an electric power conversion
apparatus.
BACKGROUND ART
[0002] With conventional techniques, electric vehicles and hybrid
vehicles have a typical configuration in which a rotating electric
machine and an electric power conversion apparatus are mounted on
the vehicle as separate respective components. From the perspective
of the mounting space for mounting such components in the vehicle,
and from the perspective of the optimum cooling method for cooling
such components, in many cases, such components are preferably
mounted as separate respective components. However, from the
perspective of the demand to reduce the number of components, and
from the perspective of a requirement to prevent surge from
occurring between the rotating electric machine and the electric
power conversion apparatus, such components are preferably
configured as a single unit.
CITATION LIST
Patent Literature
[0003] PATENT DOCUMENT 1: Japanese Laid Open Patent Publication No.
2005-224008
SUMMARY OF INVENTION
Technical Problem
[0004] Patent document 1 discloses an inverter-integrated rotating
electric machine. Such an inverter-integrated rotating electric
machine employs a configuration including a cooling tank or the
like, leading to a problem in that such an apparatus is required to
have a large overall size.
[0005] The present invention provides a technique for allowing a
rotating electric machine (rotating electric machine system)
monolithically integrated with an electric power conversion
apparatus to have a reduced size without a worsening of its
performance.
Solution to Problem
[0006] According to the 1st aspect of the present invention, a
rotating electric machine system comprises: a rotating electric
machine including a stator and a rotor arranged with a gap to the
stator; a casing configured to hold the stator; an electric power
conversion apparatus held by the casing, and configured to drive
the rotating electric machine; and a first cooling flow path
arranged in a portion of the casing between the stator and the
electric power conversion apparatus, via which cooling medium is
caused to flow so as to cool the stator and the electric power
conversion apparatus, wherein: the electric power conversion
apparatus comprises a power module configured to include a power
semiconductor element therein; the power module comprises a heat
radiation fin; and the heat radiation fin is arranged to protrude
toward a cooling medium side via an opening formed between the
power module and the first cooling flow path.
[0007] According to the 2nd aspect of the present invention, in the
rotating electric machine system according to the 1st aspect, it is
preferred that: the rotating electric machine system further
comprises a second cooling flow path arranged in a portion of the
casing outside of the stator to extend along a direction of
rotation of the rotating electric machine, via which the cooling
medium flows; and the second cooling flow path communicates with
the first cooling flow path such that the cooling medium cools the
stator after cooling the electric power conversion apparatus.
[0008] According to the 3rd aspect of the present invention, in the
rotating electric machine system according to the 2nd aspect, it is
preferred that: the first cooling flow path has a structure
configured to change a direction in which the cooling medium flows;
and the second cooling flow path communicates with the first
cooling flow path such that the cooling medium cools the stator
after cooling the electric power conversion apparatus and the
second cooling flow path has a greater cross-sectional area than a
cross-sectional area of the first cooling flow path at a
communicating portion.
[0009] According to the 4th aspect of the present invention, in the
rotating electric machine system according to the 1st aspect, it is
preferred that: the power module is configured to include power
semiconductor elements in two rows; and the first cooling flow path
is configured such that the cooling medium cools the power
semiconductor elements arranged in a first row, following which a
direction in which the cooling medium flows is changed, and the
cooling medium cools the other power semiconductor elements
arranged in a second row.
[0010] According to the 5th aspect of the present invention, in the
rotating electric machine system according to the 1st aspect, it is
preferred that: the rotating electric machine system further
comprises a temperature sensor arranged in a vicinity of the heat
radiation fin; and cooling is controlled based upon temperature
data acquired by the temperature sensor.
[0011] According to the 6th aspect of the present invention, a
rotating electric machine system comprises: a rotating electric
machine including a stator and a rotor configured to rotate with a
gap to the stator; an electric power conversion apparatus held by a
casing configured to hold the stator, and configured to drive the
rotating electric machine; a first cooling flow path arranged at a
portion of the casing between the stator and the electric power
conversion apparatus, via which cooling medium is caused to flow so
as to cool the electric power conversion apparatus; and a second
cooling flow path arranged in a portion of the casing outside of
the stator, and configured such that the stator is cooled by the
cooling medium that flows via the second cooling flow path along a
direction of rotation of the rotating electric machine, wherein:
the first cooling flow path has a structure configured to change a
direction in which the cooling medium flows; and the second cooling
flow path communicates with the first cooling flow path such that
the cooling medium cools the stator after cooling the electric
power conversion apparatus, and the second cooling flow path has a
greater cross-sectional area than a cross-sectional area of the
first cooling flow path at a communicating portion.
[0012] According to the 7th aspect of the present invention, in the
rotating electric machine system according to the 6th aspect, it is
preferred that: the electric power conversion apparatus comprises a
power module configured to include power semiconductor elements in
two rows; and the first cooling flow path is configured such that
the cooling medium cools the power semiconductor elements arranged
in a first row, following which a direction in which the cooling
medium flows is changed, and the cooling medium cools the other
power semiconductor elements arranged in a second row.
[0013] According to the 8th aspect of the present invention, in the
rotating electric machine system according to the 7th aspect, it is
preferred that: a heatsink plate of the power module includes a
heat radiation fin; and the heat radiation fin is configured to
protrude toward a cooling medium side via an opening formed between
the power module and the first cooling path.
[0014] According to the 9th aspect of the present invention, in the
rotating electric machine system according to the 8th aspect, it is
preferred that: the rotating electric machine system further
comprises a temperature sensor in a vicinity of the heat radiation
fin; and cooling is controlled based upon temperature data acquired
by the temperature sensor.
Advantageous Effect of the Invention
[0015] An electric power conversion apparatus employing a direct
water cooling method provides low thermal resistance as compared
with an electric power conversion apparatus employing a typical
indirect water cooling method. Thus, such an arrangement requires
only a small area to cool power semiconductor elements. That is to
say, a water flow path is shared by the rotating electric machine
and the electric power conversion apparatus, which are integrally
configured as a single unit. Furthermore, the electric power
conversion apparatus is cooled by means of a direct cooling method.
Thus, such an arrangement provides a rotating electric machine
system including a small-size electric power conversion
apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is an external view (1) of a rotating machine
system.
[0017] FIG. 2 is an external view (2) of the rotating machine
system.
[0018] FIG. 3 is an external view (3) of the rotating machine
system.
[0019] FIG. 4 is an external view (4) of the rotating machine
system.
[0020] FIG. 5 is a main circuit diagram.
[0021] FIG. 6 is a diagram for describing a comparison between a
direct water cooling method and an indirect water cooling
method.
[0022] FIG. 7 is a diagram (1) for describing a flow path structure
(U-turn structure).
[0023] FIG. 8 is a diagram (2) for describing the flow path
structure (relation 1 between the inlet and the outlet for cooling
water).
[0024] FIG. 9 is a diagram (3) for describing the flow path
structure (relation 2 between the inlet and the outlet for cooling
water).
[0025] FIG. 10 is an external view (1) of a power module (internal
layout).
[0026] FIG. 11 is an external view (2) of the power module
(relation between fins and water flow).
DESCRIPTION OF EMBODIMENTS
[0027] FIGS. 1 through 4 show an embodiment of the present
invention. FIG. 5 shows a main circuit according to the present
embodiment, and shows a configuration of how each principal
component is electrically connected. For convenience, the electric
power conversion apparatus will be referred to as the "inverter"
and the rotating electric machine will be referred to as the
"motor" hereafter. It should be noted that such a rotating electric
machine functions not only as a motor but also functions as a
generator. The motor includes a stator, and a rotor (not shown)
arranged so as to rotate with a gap between it and the stator.
Furthermore, the inverter is held by a housing configured to hold
the stator, and is configured to drive the motor.
[0028] First, description will be made regarding an electrical
function of the present embodiment. The portion surrounded by a
broken line corresponds to an inverter-integrated motor 1 which
will be described in the present embodiment. The
inverter-integrated motor 1 can be roughly classified into two
units, i.e., an inverter unit 2 and a motor unit 3. The inverter
unit 2 is configured to perform switching of a power semiconductor
element 5 in a regular manner so as to convert input (DC) electric
power into AC electric power, and to transmit the AC electric power
thus converted to the motor unit 3. Here, the motor is represented
by the motor impedance 7 of the motor coil in the electric circuit
diagram shown in FIG. 5. The AC electric power converted by the
inverter passes through the motor impedance 8. Description will be
made in the present embodiment assuming that the power
semiconductor element 5 is configured as an IGBT (Insulated Gate
Bipolar Transistor). Also, other kinds of power semiconductor
elements (e.g., MOS-FET etc.) may be employed depending on the
required frequency and voltage. Description will be made below
regarding an arrangement including three IGBTs 5a and three
flywheel (freewheel) diodes 6a on the positive electrode side
(upper arm side) and the same number of IGBTs 5b and flywheel
diodes 6b on the negative electrode side (lower arm side). With
such an arrangement, each upper arm and lower arm pair corresponds
to a single corresponding phase.
[0029] The pulsation (ripple) that occurs in the switching
operation is smoothed by a smoothing capacitor 21 arranged between
the battery 4 and a set of the power semiconductor elements 5.
[0030] Next, description will be made with reference to FIG. 1. The
rectangular parallelepiped portion arranged in the upper portion in
FIG. 1 corresponds to the inverter unit 2, and the cylindrical
portion in the lower portion corresponds to the motor unit 3.
Description will be made in the present embodiment regarding an
arrangement in which a single metal housing (outer housing 10) is
shared by the inverter unit 2 and the motor unit 3, thereby forming
a monolithically integrated unit. That is to say, the upper section
of the outer housing 10 corresponds to the inverter unit 2.
[0031] The interior space of the inverter unit 2 corresponds to an
inverter chamber 13 mounting components configured to provide a
function as an inverter. In practical use, a cover, which is not
shown in the drawing in order to show the interior, is arranged at
the top portion of the inverter unit in order to prevent foreign
matter or fluid from contaminating the interior of the inverter
chamber 13.
[0032] As can be clearly understood with reference to FIGS. 1 and
2, an inner housing 11 configured as a separate unit is arranged on
the inner side of the outer housing 10 of the motor unit 3.
Furthermore, a coil 14 of the motor is arranged on the inner side
of the inner housing 11. The outer housing 10 includes a flange 12
which allows the inverter-integrated motor 1 to be mounted on an
engine, transmission, gearbox, or the like, of a vehicle. Bolt
holes are formed in the flange 12 in a desired manner, which are
not shown in the drawing.
[0033] As shown in FIGS. 1 and 3, the inverter chamber 13 includes
a motor control board 20 configured to control the motor, a
smoothing capacitor 21 configured to smooth voltage ripples, a gate
driving board 22 configured to control the on/off operation of the
switching element according to an instruction received from the
motor control board, and a power module 23 mounting the power
semiconductor elements 5, with these components arranged such that
they are stacked in this order, beginning from the top, and with
the power module 23 as the bottom portion of the inverter unit. The
inverter according to the present embodiment includes a discharging
resistor 25. When the inverter is turned off, the charge stored in
the smoothing capacitor 21 is discharged via the discharging
resistor 25. A signal connector 26 is arranged on the external wall
of the inverter chamber 13, which allows signals to be
transmitted/received between the inverter and the vehicle side. The
signal connector 26 is connected to one terminal of a flat cable 27
on the inner side of the wall of the inverter chamber 13. The other
terminal of the flat cable 27 is connected to the motor control
board 20.
[0034] The DC electric power received from an external battery 4 is
input via a high-electric-power connector 28 arranged at one
terminal of the inverter unit 2. The DC electric power is
transmitted to a DC terminal 55 of the power module 23, and is
converted by the power module 23 into AC electric power. The AC
electric power thus converted is transmitted to the coil 14 via a
lead wire 17 from an AC terminal 56 of the power module 23. In this
state, the AC current is transmitted to the coil 14 via a current
sensor 24. The AC current that passes through this path is detected
by the current sensor 24. The current value of the AC current thus
detected is transmitted to the motor control board 20, and is used
to control the motor. The connection line that connects the lead
wire 17 and the power module 23 is designed to be as short as
possible in order to suppress the effects of surge and noise.
[0035] FIG. 6 is a schematic diagram showing a longitudinal
configuration of the power module 23. FIGS. 10 and 11 are detailed
external diagrams showing the power module 23. The power module 23
includes, in its lower portion, a heatsink plate 42 configured to
release heat generated in the switching operation of the power
semiconductor elements 5 arranged as internal components thereof.
Fins 43 configured to radiate or release heat are arranged on the
bottom face of the heatsink plate 42. Description is being made in
the present embodiment regarding an arrangement in which the fins
43 are arranged as multiple cylindrical pin-shaped fins. However,
the fins 43 may be formed in other shapes. The power module 23 is
fixed by engaging each bolt 57 with a corresponding bolt hole 36
such that the power module 23 functions as a cover for an opening
35 formed in the bottom face of the inverter chamber 13. In this
state, the fins 43 are arranged such that they protrude downward
via the opening 35.
[0036] FIG. 7 shows only the inner housing 11. A cooling flow path
37 having a long recessed belt-like structure is formed along the
circumference of the outer face of the inner housing 11. The
cooling flow path 37 is arranged around the surface of the inner
housing in an approximately belt-like structure. By mounting the
inner housing 11 within the outer housing 10, the outer housing 10
functions as a cover for the cooling flow path 37. In this state, a
flow path inlet 39 is arranged downstream of an inlet pipe 15.
Furthermore, O-rings or otherwise liquid sealing members are
arranged on both sides of the cooling flow path 37 such that they
extend in parallel with each other around the inner housing, which
are not shown in the drawing, thereby providing a measure for
preventing water leakage.
[0037] The fins 43 of the power module 23 are arranged such that
they protrude via the opening 35 toward the flat face 38 of the
cooling flow path 37. That is to say, the present embodiment
employs a direct water cooling method in which heat generated by
the power semiconductor elements 5 reaches the fins 43
monolithically integrated with the heatsink plate 42 via the
heatsink plate 42, and the power semiconductor elements 5 are
cooled by directly cooling the fins 43. It should be noted that
description is being made assuming that water cooling using cooling
water is employed. However, the cooling medium is not restricted to
water.
[0038] FIG. 6 is a schematic diagram showing a longitudinal
internal structure of the power module 23 in order to make a
comparison between a direct water cooling method and an indirect
water cooling method. FIG. 6(a) shows an arrangement employing a
direct water cooling method, and FIG. 6(b) shows an arrangement
employing an indirect water cooling method. Typically, the power
module 23 has a longitudinal internal structure including the power
semiconductor elements 5, an insulating substrate 45, and the
heatsink plate 42 arranged in this order, beginning from the
top.
[0039] With such an indirect water cooling arrangement, the fins 43
are arranged on the water flow path side of the casing inner wall
47 of the inverter casing 46. The power module 23 is arranged on
the opposite face of the casing inner wall 47 with respect to the
fins 43. At this stage, typically, thermal grease 48 is applied
between the heatsink plate 42 of the power module and the inner
wall 47 of the inverter casing, thereby contributing to improving
the thermal conductivity of the interface at which a metal member
is in contact with another metal member. That is to say, heat
generated by the power semiconductor elements 5 is radiated or
released to cooling water 44 from the heatsink plate 42 via the
thermal grease 48 and the inverter casing inner wall 47.
[0040] With such a direct water cooling arrangement, the power
module 23 is fixed at the inverter casing 46 in the same way as the
aforementioned indirect water cooling arrangement. The point of
difference between these arrangements is that, with such a direct
water cooling arrangement, an opening is formed in the face on
which the power module 23 is to be mounted, and the power module 23
is mounted so as to cover the opening. That is to say, with such an
arrangement in which the fins 43 are arranged on the heatsink plate
42, the fins 43 are arranged such that they protrude on the cooling
water side. Thus, the cooling water 44 is directly in contact with
the heatsink plate 42 and the fins 43, thereby releasing heat
generated by the power semiconductor elements 5.
[0041] With such an arrangement employing an indirect water cooling
method, the thermal resistance through the path from the power
semiconductor elements (IGBTs) 5 to the cooling water 44 is on the
order of 0.15.degree. C./W. With such an arrangement employing a
direct water cooling method, the thermal resistance is on the order
of 0.09.degree. C./W. That is to say, an arrangement employing an
indirect water cooling method provides a thermal resistance 1.5
times higher than with a direct water cooling method. In other
words, from the perspective of the required heatsink area, such an
arrangement employing a direct water cooling method requires the
power module 23 to have only a small bottom area, which is 1/1.5
smaller than that in a case in which an indirect water cooling
method is employed.
[0042] For such an inverter-integrated motor having a configuration
in which an inverter is mounted on a housing of the motor, it is
important to allow the inverter to have a small bottom area, as
compared with an arrangement in which an inverter and a motor are
mounted as separate respective units. Thus, such a direct water
cooling method can be effectively applied to the present
embodiment. At the same time, such an arrangement provides
increased torque per volume as compared with an arrangement
employing an indirect water cooling method.
[0043] Furthermore, as shown in FIG. 10, the power module 23
employed in the present embodiment has a layout in which six power
semiconductor elements 5 are arranged such that three of the power
semiconductor elements 5 respectively face the other three power
semiconductor elements 5 (i.e., the power semiconductor elements 5
are arranged in two rows in parallel), thereby allowing the water
flow path to have a reduced length in the longitudinal direction.
That is to say, such an arrangement provides a power module
structure suitable for mounting on a cylindrical motor housing.
[0044] Furthermore, the present invention has the following
function for cooling the power module 23. Typically, the cooling
flow path 37 shown in FIG. 7 is designed assuming that fluid flows
in one direction from the inlet to the outlet. However, with the
present embodiment as shown in FIG. 7, the cooling flow path 37 is
formed such that fluid makes a U-turn at a flat portion 38 that
corresponds to the lower portion of the power module. In this
region, the water flow path has a narrow width. Thus, such an
arrangement provides an increased flow rate (or flow velocity) at
the lower portion of the power module, thereby effectively cooling
the six power semiconductor elements 5 arranged as internal
components while requiring only a small cooling space.
[0045] With the present embodiment, the cooling flow path 37 is
formed of two cooling flow paths (i.e., a first cooling flow path
and a second cooling flow path). The first cooling flow path is
provided to the casing portion between the stator and the electric
power conversion apparatus, thereby cooling the electric power
conversion apparatus by means of a cooling medium that flows
through the flow path. In this stage, the flow direction of the
cooling medium changes after it has cooled the power semiconductor
elements arranged in the first row, following which it cools the
other power semiconductor elements arranged in the second row.
Meanwhile, the second cooling flow path is provided to the casing
portion outside of the stator. By means of the cooling medium
flowing via the flow path around the rotating electric machine
along the motor rotation direction, such an arrangement is capable
of cooling the stator.
[0046] As described above, in FIG. 7, the first cooling flow path
has a structure configured such that the cooling medium makes a
U-turn at the flat portion 38. FIG. 7 shows such a cooling flow
path structure configured such that the cooling medium makes a
U-turn for exemplary purposes only. Also, the first cooling flow
path may be configured in other structures as long as the flow
direction of the cooling medium changes at the flat portion 38 so
as to raise the flow rate (or flow velocity) of the cooling
medium.
[0047] The second cooling flow path is formed such that it
communicates with the first cooling flow path such that the cooling
medium cools the stator after it has cooled the inverter.
Furthermore, the second cooling flow path employs a structure
configured such that, at the communicating portion, the second
cooling flow path has a greater cross-sectional area than that of
the first cooling flow path.
[0048] With the present embodiment, the cooling water has a
function as motor cooling water for cooling the motor stator core
and the coil 14, in addition to a function for cooling the inverter
unit 2.
[0049] The important point to be noted here is the difference
between the allowable temperature of the coil 14 of the motor and
the operating temperature of the power module 23. Typically, the
coil 14 of the motor is likely to have a high temperature.
Accordingly, the temperature of the cooling water rises when it
flows around the outer housing 10 and the inner housing 11. In
ordinary cases, the maximum temperature of the coil 14 is estimated
to reach up to a temperature in the vicinity of 180.degree. C.
However, the upper limit of the operating temperature of the power
module 23 is on the order of 125.degree. C. to 150.degree. C.,
which includes an increase in the temperature due to the heat
generated by the power module 23 itself. That is to say, such an
inverter-integrated motor requires a design for suppressing to a
minimum the effects of the temperature of the coil 14 on the power
module 23.
[0050] FIG. 8 is a simplified cross-sectional diagram showing the
present embodiment. The arrow indicates the cooling water flow. In
the drawing, the cooling water input via the inlet pipe 15 makes a
U-turn after it passes below the heatsink plate 42 of the power
module 23 and through between the fins 43, as shown in FIG. 7.
Thus, at this position (right side of the flat face 38 of the flow
path) in FIG. 8, the cooling water flows toward the back of the
drawing. Subsequently, the cooling water flows around the
circumference of the motor coil counterclockwise in the figure, and
flows toward the output pipe 16. As described above, the present
embodiment is designed such that the distance between the inlet
pipe 15 for the cooling water and the power module 23 is reduced as
much as possible, thereby cooling the power module 23 in the first
stage using the cooling water at its lowest temperature. By
employing such a design, such an arrangement is capable of
suppressing to a minimum the thermal effects of the high
temperature of the coil 14 on the power module 23.
[0051] Also, FIG. 9 shows a modification obtained by modifying the
structure of the inlet pipe 15 shown in FIG. 8. Such a modification
has a structure in which the inlet pipe 15 is arranged in parallel
with the flat portion 38. Thus, such a modification provides
increased momentum in the flow of the cooling water input via the
inlet pipe 15, thereby providing an increased flow rate as compared
with an arrangement shown in FIG. 8. As a result, such a
modification provides a structure with improved effectiveness of
cooling the power semiconductor elements 5 without involving a
large cooling space.
[0052] It should be noted that description has been made with
reference to an example in which the inverter unit 2 and the motor
unit 3 are completely monolithically integrated as a single unit.
Also, such an inverter unit 2 and a motor unit 3 may be formed as
separate respective units, and these separate units may be
monolithically integrated in a subsequent stage, thereby providing
an inverter-integrated motor. Examples of the advantages of such an
arrangement include an advantage in that, in a case in which either
one of the inverter unit 2 or the motor unit 3 is damaged, such an
arrangement requires that only the damaged unit be repaired, and so
forth. However, it should be noted that such an arrangement
requires a sealing member such as an O-ring or the like to be
applied to the interface between the two units.
[0053] The temperature of the cooling water 44 corresponds to the
temperature of the motor cooling water, and at the same time
corresponds to the temperature of the inverter cooling water. That
is to say, a temperature sensor may be arranged in the vicinity of
the fins 43 immersed in the cooling water 44, which is not shown in
the drawing showing the present embodiment, and the information
obtained by the temperature sensor may be supplied to the motor
control board 20, thereby allowing the water temperature for
cooling the motor and the water temperature for cooling the
inverter to be controlled at the same time. Such an arrangement can
be effectively applied to an arrangement in which each component is
required to be maintained in its own temperature range, or an
arrangement in which cooling should be controlled for each
component. For example, such an arrangement enables a control
operation in which the current is controlled (i.e., a limit is
placed on the torque) according to the water temperature in a case
in which there is a high probability of increased water temperature
having adverse effects on the power module or otherwise on the
stator side of the motor.
[0054] Description has been made above regarding various kinds of
embodiments and modifications. However, the present invention is
not restricted to the contents of such embodiments and
modifications. Also, various other kinds of embodiments may be made
without departing from the technical scope of the present
invention, which are also encompassed in the present invention.
[0055] The entire contents disclosed in Japanese Patent Application
No. 2010-041233 (filed on Feb. 26, 2010) are incorporated herein by
reference.
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