GB2560337A

GB2560337A - Cooling plate

Info

Publication number: GB2560337A
Application number: GB1703650.0A
Authority: GB
Inventors: Tsonev Kaloyan; Smith Richard
Original assignee: Arrival Ltd
Current assignee: Arrival UK Ltd
Priority date: 2017-03-07
Filing date: 2017-03-07
Publication date: 2018-09-12
Anticipated expiration: 2037-03-07
Also published as: GB2560337A9; GB201703650D0; GB2560337B

Abstract

A cooling plate 40 comprising a recess 47 and a mounting surface for an electronic power controller. The recess has a bottom surface with two inlet holes 58, 59 and two outlet holes 60, 61 allowing cooling fluid to enter and leave the recess. The inlet and outlet holes may be arranged at opposite ends of the recess, preferably minor sides 53, 54 of a rectangular recess or with each hole in a respective corner. One of the holes 58, 60 may be larger than the other 59, 61 for both the inlet and outlet holes, the larger holes preferably being 4 times the size of the others. The inlets and outlets may have inner conduits 62, 64. The cooling plate may be ceramic and may have a heat sink. A pump may be included to form a cooling system. An assembly of the cooling plate 40 with a power controller 4 is discussed. The power controller may have a plurality of switching transistors 8-10 on a backing plate 4, which may have a plurality of, preferably conical, protrusions. The protrusions may be arranged in columns and offset rows. A vehicle comprising the power controller assembly is disclosed.

Description

(54) Title of the Invention: Cooling plate

Abstract Title: Cooling plate for an electronic power controller (57) A cooling plate 40 comprising a recess 47 and a mounting surface for an electronic power controller. The recess has a bottom surface with two inlet holes 58, 59 and two outlet holes 60, 61 allowing cooling fluid to enter and leave the recess. The inlet and outlet holes may be arranged at opposite ends of the recess, preferably minor sides 53, of a rectangular recess or with each hole in a respective corner. One of the holes 58, 60 may be larger than the other 59, 61 for both the inlet and outlet holes, the larger holes preferably being 4 times the size of the others. The inlets and outlets may have inner conduits 62, 64. The cooling plate may be ceramic and may have a heat sink. A pump may be included to form a cooling system. An assembly of the cooling plate 40 with a power controller 4 is discussed. The power controller may have a plurality of switching transistors 8-10 on a backing plate 4, which may have a plurality of, preferably conical, protrusions. The protrusions may be arranged in columns and offset rows. A vehicle comprising the power controller assembly is disclosed.

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Cooling Plate

Field

This disclosure relates to a cooling plate for an electronic power controller, particularly 5 but not exclusively a cooling plate for an electronic power controller for an electric, hybrid, or range-extended vehicle. This disclosure also relates to a cooling system for an electronic power control system, and to a vehicle having the cooling system and electronic power controller.

Background

Electric, hybrid and range-extended vehicles run on high power electricity that powers electric motors to drive the vehicle. The electric power, usually supplied from batteries, is passed through a power controller that generates the appropriate power supply for the electric motors. For example, the power controller may convert a DC power input from a battery into a 3-phase power output for the electric motor.

Due to the high power of such a system the power controller can generate significant excess heat that may be to the detriment of the function of the power control circuitry within the controller. Known cooling systems use water to cool power controllers, and this involves passing the water across a surface of the power controller so that heat is absorbed in the water and carried away. Water is provided to the cooling system via a water inlet and exits via a water outlet. However, known cooling systems can result in a temperature gradient across different parts of the power control circuitry because parts closer to the water inlet will be cooled to a greater extent than parts closer to the water outlet.

Summary

According to a first aspect of the invention, there is provided a cooling plate for an electronic power controller, the cooling plate comprising:

a recess and a mounting surface arranged such that said electronic power controller is attachable to the mounting surface to cover the recess and form a cooling fluid chamber, the recess having an opposing surface that is facing said electronic power controller when said electronic power controller is attached to the mounting surface;

a first inlet hole and a second inlet hole disposed in the opposing surface of the recess; and, a first outlet hole and a second outlet hole disposed in the opposing surface of the recess;

and wherein, during use, cooling fluid enters the cooling fluid chamber via first inlet hole and second inlet hole and exits the cooling fluid chamber via the first outlet hole and second outlet hole.

In some examples, the recess may comprise a first end and a second end, the second 10 end being opposite the first end, and wherein the first inlet hole and second inlet hole are disposed adjacent the first end of the cooling fluid chamber, and the first outlet hole and second outlet hole are disposed adjacent the second end of the cooling fluid chamber.

In preferred examples, the recess is rectangular and comprises first and second major sides and first and second minor sides, the first and second major sides having a greater length than the first and second minor sides.

The first inlet hole and the second inlet hole may be disposed adjacent the first minor side of the recess, and the first outlet hole and the second outlet hole may be disposed adjacent the second minor side of the recess.

Each of the first inlet hole, second inlet hole, first outlet hole, and second outlet hole may be disposed adjacent a different corner of the bottom surface of the recess.

The first inlet hole and second inlet hole may be equidistant from the first minor side wall of the recess. Additionally, the first outlet hole and second outlet hole maybe equidistant from the second minor side wall of the recess.

The first inlet hole and the first outlet hole may be equidistant from the first major side of the recess.

The second inlet hole may be spaced from the second major side of the recess by a greater distance than the second outlet hole is spaced from the second major side of the recess.

-3A spacing between the first outlet hole and the second outlet hole maybe greater than a spacing between the first inlet hole and the second inlet hole.

The second inlet hole and the second outlet hole may be arranged such that during use 5 cooling fluid flowing between the second inlet hole and second outlet hole does not mix with fluid flowing between the first inlet hole and first outlet hole.

The first inlet hole may be larger than the second inlet hole, and the first outlet hole may be larger than the second outlet hole.

The first inlet hole may be larger than the second inlet hole.

The size of the first inlet hole may be between 3 and 5 times the size of the second inlet hole. Preferably, the size of the first inlet hole is approximately 4 times of the size of the second inlet hole.

The first outlet hole may be larger than the second outlet hole.

The size of the first outlet hole may be between 3 and 5 times the size of the second 20 outlet hole. Preferably, the size of the first outlet hole is approximately 4 times the size of the second outlet hole.

The cooling plate may further comprise an inlet conduit that is in fluid communication with the first inlet hole and the second inlet hole.

The inlet conduit may be arranged such that the second inlet hole is downstream of the first inlet hole when cooling fluid flows through the inlet conduit during use.

The size of the inlet conduit may be greater than the size of the second inlet hole.

The size of the inlet conduit may be greater than the size of the first inlet hole.

The inlet conduit may extend through the cooling plate in a direction parallel to the opposite surface of the recess.

-4The cooling plate may further comprise an outlet conduit that is in fluid communication with the first outlet hole and the second outlet hole.

The outlet conduit may be arranged such that the first outlet hole is downstream of the 5 second outlet hole when cooling fluid flows into the outlet conduit via the first outlet hole and second outlet hole.

The size of the outlet conduit may be greater than the size of the second outlet hole.

The size of the first outlet hole may be approximately equal to the size if the outlet conduit.

The outlet conduit may extend through the cooling plate in a direction parallel to the opposite surface of the recess.

The cooling plate may be made of a ceramic.

The cooling plate may further comprise a heat sink.

According to a further aspect of the present invention, there is also provided a cooling system for an electronic power controller, the cooling system comprising the cooling plate described above and a pump arranged to circulate cooling fluid through the cooling fluid chamber via the first inlet hole, second inlet hole, first outlet hole, and second outlet hole.

According to a further aspect of the present invention, there is also provided an electronic power control assembly comprising the cooling plate described above and an electronic power controller attached to the cooling plate.

In preferred examples, the electronic power controller may comprise a backing plate and a plurality of switching transistors mounted to the backing plate.

The backing plate may comprise a plurality of protrusions that are arranged to protrude into the cooling fluid chamber when the electronic power controller is attached to the cooling plate.

-5The plurality of protrusions maybe conical.

The plurality of protrusions may extend at least 75% of the distance across the recess towards the opposing surface.

The protrusions maybe arranged in columns and offset rows.

The electronic power control assembly may comprise three power controllers arranged adjacently in a line.

The electronic power controller may comprise a high power switch adapted to output power for an electric motor.

The electronic power controller may comprise a metal-oxide-semiconductor field15 effect transistor, or an insulated-gate bipolar transistor.

According to a further aspect of the present invention, there is also provided a vehicle comprising the electronic power control assembly described above.

The vehicle may further comprise an electric motor arranged to provide a driving force for the vehicle.

The vehicle may be an electric, hybrid, or range-extended vehicle.

Brief Description of the Drawings

Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic diagram of an electric drive system for a vehicle;

FIG. 2 shows an electronic power controller;

FIG. 3 shows a cooling plate according to the prior art;

FIG. 4 shows a cross-section of the cooling plate of FIG. 3 and the electronic power controller of FIG. 2, during use;

FIG. 5 shows the backplate of the electronic power controller of FIG. 2;

FIG. 6 shows an example cooling plate of the present invention;

FIG. 7 shows a cross-section of the example cooling plate of FIG. 6;

-6FIG. 8 shows a cross-section of the example cooling plate of FIG. 6, together with an electronic power controller;

FIG. 9 shows a top view of an example cooling plate of the present invention;

FIG. io shows a schematic diagram of part of an example cooling plate of the present invention;

FIG. it shows a schematic diagram of part of an example cooling plate of the present invention; and,

FIG. 12 shows an example cooling plate of the present invention.

io

Detailed Description

FIG. l shows a schematic diagram of an electric drive system l for a vehicle 2. The electric drive system l includes a battery 3, a power controller 4, and an electric motor 5. The battery 3 provides DC current to the power controller 4. In this example, the electric motor 5 runs on three phase current, and the power controller 4 modulates the DC current into the three phase power output for driving the electric motor 5. The electric motor 5 is coupled to the drive mechanism 6 of the vehicle 2, for example a drive shaft or wheel, for driving the vehicle 2.

The power controller 4, illustrated in FIG. 2, comprises a backplate 7 and three switching transistors 8, 9,10 mounted to the backplate 7. The switching transistors 8,

9,10 include electrical terminals (not shown) for connecting wires that connect the power controller 4 to the battery 3 (see FIG. 1) and electric motor 5 (see FIG. 1). Each switching transistor 8, 9,10 is configured to generate an AC power output from a DC power input received from the battery 3 (see FIG. 1). Together, the three switching transistors 8, 9,10 provide 3 phase power.

As illustrated, the backplate 7 of the power controller is cuboid. In particular, the backplate 7 is planar, with a first major side 11, a second major side 12, a first minor side 13, and a second minor side 14, the major sides 11,12 being longer than the minor sides 13,14. The depth of the backplate 7 is significantly less than the it’s other dimensions. The switching transistors 8, 9,10 are mounted to a top surface 15 of the backplate 7.

In this example, the backplate 7 is cuboid, i.e. the first and second major sides 11,12 are parallel to each other, the first and second minor sides 13,14 are parallel to each other,

-Ίand the first and second major sides 11,12 are perpendicular to the first and second minor sides 13,14. As illustrated, the switching transistors 8, 9,10 are mounted to the top surface 15 of the backplate 7 in a line, with one switching transistor 10 at a first end of the backplate 7, adjacent the first minor side 13, one switching transistor 8 at a second end of the backplate 7, adjacent the second minor side 14, and the third switching transistor 9 disposed in between the other switching transistors 8,10.

In one example, the switching transistors 8, 9,10 are each an insulated-gate bipolar transistor (IGBT). In other examples the switching transistors 8, 9,10 may alternatively comprise a metal-oxide-semiconductor field-effect transistor (MOSFET). In other examples, the switching transistors 8, 9,10 may comprise Gallium Nitride based field effect transistors (GaN FET). The semi-conductors of the switching transistors 8, 9,10 maybe arranged in a multitude of combinations (both parallel and series connected) to provide the correct voltage and current magnitude required by the motor drive system.

Electric vehicles use high power systems to drive the electric motors. For example, the electric drive system may run on 2 kilowatts or more of DC power from the battery system to drive compressors and/or pumps to provide air and hydraulic services to the vehicle for braking and steering assistance. Generally much higher power levels are required for propulsion; for small passenger cars 3O-5OkW of electrical power is common. For commercial vehicles 50-iookW of electrical drive power is common, and for racing applications much higher powers are required from ioo-25okW, or above.

The power controller 4, in particular the switching transistors 8, 9,10, generate excess heat during operation. This excess heat may reduce the operating efficiency of the switching transistors 8, 9,10 and may cause damage to the semi-conductors of the switching transistors 8, 9,10. In particular, the switching transistors 8, 9,10 may include semi-conductors that perform less efficiently at elevated temperatures. In addition, operating temperature differences between the switching transistors 8, 9,10 of the power controller 4 may degrade performance. Therefore, it is desirable to cool the power controller 4 during operation, and to provide uniform temperature across the power controller 4.

The power controller 4 illustrated in FIG. 2 and described above maybe a part of a larger power control system. For example, additional power control electronics may be included.

-8FIG. 3 and FIG. 4 illustrate a cooling system 20 for the power controller 4 described with reference to FIGS. 1 and 2. The cooling system 20 of FIG. 3 and FIG. 4 is a conventional arrangement for cooling the power controller 4, and is known in the prior art.

The cooling system 20 comprises a cooling plate 21 that is cuboidal and adapted such that the power controller 4 is attachable to the cooling plate 21 as shown in FIG. 4. The cooling plate 21 comprises a substantially similar shape to the backplate 7 of the power controller 4. That is, the cooling plate 21 is cuboidal, having a first major side 22, a second major side 23, a first minor side 24, and a second minor side 25, and the first and second major sides 22, 23 are longer than the first and second minor sides 24, 25. The cooling plate 21 is substantially planar, with a depth that is significantly less than the length of the minor and major sides 22, 23, 24, 25. In this example, the first and second major sides 22, 23 are parallel to each other, the first and second minor sides 24, 25 are parallel to each other, and the first and second major sides 22, 23 are perpendicular to the first and second minor sides 24, 25. In this way, the cooling plate 21 has a top surface 26 and a bottom surface 27.

As illustrated, the top surface 26 of the cooling plate 21 includes a recess 28. The power controller 4 is attachable to the cooling plate 21 such that it covers the recess 28. The recess 28 defines a cooling fluid chamber 29, shown most clearly in FIG. 4.

In this example, the top surface 26 of the cooling plate 21 includes a mounting surface

30 that is receded from the top surface 26 of the cooling plate 21. The mounting surface is adapted to receive the power controller 4. The mounting surface 30 includes fixing holes 31 that correspond to fixing holes 32 in the backplate 7 of the power controller 4 (see FIG. 2) for attaching the power controller 4 to the cooling plate 21.

In this example, the recess 28 is cuboidal, having a first major side 33, a second major side 34, a first minor side 35, and a second minor side 36, the first and second major sides 33, 34 being longer than the first and second minor sides 35, 36. In this example, the first and second major sides 33,34 are parallel to each other, the first and second minor sides 35,36 are parallel to each other, and the first and second major sides 33,

34 are perpendicular to the first and second minor sides 35, 36.

-9The cooling plate 21 also includes an inlet 37 and an outlet 38. The inlet is formed in the first minor side 24 of the cooling plate and extends through to the first minor side 35 of the recess 28, and the outlet 38 is formed in the second minor side 25 of the cooling plate 21 and extends through to the second minor side 26 of the recess 28, such that the inlet and the outlet are disposed at opposing ends of the cooling plate 21.

As illustrated in FIG. 4, the backplate 7 of the power controller 4 includes a plurality of protrusions 66 that extend into the cooling fluid chamber 29. The protrusions 66 increase the surface area of the backplate 7 that is exposed to the cooling fluid, thereby increasing heat transfer to the cooling fluid.

As indicated in FIG. 4, during use cooling fluid enters the cooling fluid chamber 29 through the inlet 37 and exits via the outlet 38. While the cooling fluid is in the cooling fluid chamber 29 it absorbs heat from the power controller 4, in particular via the backplate 7 and protrusions 66. The cooling fluid carries the absorbed heat out of the outlet 38. The cooling fluid can then be passed through a cooler, for example a radiator or heat exchanger, before the cooling fluid is circulated back to the inlet 37. In this way, the power controller 4 is cooled and excess heat is dispersed.

Disadvantageously, the first of the switching transistors 8, being arranged adjacent to the inlet 37, is cooled to a greater extent than the second switching transistor 9 and the third switching transistor 10, which are further from the inlet 37. This creates a temperature gradient across the power controller 4, and temperature differences between the individual switching transistors 8, 9,10. This is due to the cooling fluid having a lower temperature at the inlet 37.

FIG. 5 illustrates the bottom surface of the backplate 7 that faces the cooling fluid chamber 29. An array of protrusions 66 re illustrated.

As shown in FIG. 5, the arrangement of the protrusions 66 can result in stagnant areas within the cooling fluid chamber 29, where the cooling fluid does not flow adequately, resulting in hot spots on the power controller 4. In particular, the protrusions 66 of a power controller 4 are typically arranged in rows and columns that are offset from each other to define diagonal paths between the protrusions, as shown in FIG. 5. As cooling fluid enters the cooling fluid chamber 28 at the inlet 37 in the first minor side 35 of the cooling fluid chamber 29, it will flow along the diagonal paths towards the first and

- 10 second major sides 33,34 of the cooling fluid chamber 29, along the first and second major sides 33, 34 of the cooling fluid chamber 29, and then towards the outlet 38 in the second minor side 36 of the cooling fluid chamber 29. This results in a stagnant area in the middle of the cooling fluid chamber 29 where cooling fluid does not flow adequately, reducing the cooling efficiency in the middle of the cooling fluid chamber

29. In this way, the second switching transistor 9 (see FIG. 2) may be inadequately cooled.

FIG. 6 and FIG. 7 illustrate a first example cooling plate 40 of the present invention. In 10 this example, the cooling plate 40 is cuboidal and adapted such that the power controller 4 (see FIG. 2) is attachable to the cooling plate 40. The cooling plate 40 is substantially cuboidal, having a first major side 41, a second major side 42, a first minor side 43, and a second minor side 44. The first and second major sides 41, 42 are longer than the first and second minor sides 43, 44. The cooling plate 40 is substantially planar, having a depth which is less than the length of the first and second minor sides 43,44. In this example, the cooling plate 40 is cuboidal, i.e. the first and second major sides 41, 42 are parallel to each other, the first and second minor sides 43, 44 are parallel to each other, and the first and second major sides 41, 42 are perpendicular to the first and second minor sides 43, 44. In this way, the cooling plate

40 has a top surface 45 and a bottom surface 46.

As illustrated, the top surface 45 of the cooling plate 40 includes a recess 47. The power controller 4 (see FIG. 2) is attachable to the cooling plate 40 such that it covers the recess 47. In this way, the recess 47 defines a cooling fluid chamber 48.

The top surface 45 of the cooling plate 40 includes a mounting surface 49 adapted to receive the power controller 4. The mounting surface 49 includes fixing holes 50 that correspond to the mounting holes 32 in the power controller 4, as illustrated in FIG. 2, for attaching the power controller 4 to the cooling plate 40. In this example, the mounting surface 49 is sunk relative to the top surface 45 of the cooling plate 40. However, it will be appreciated that the mounting surface 49 may alternatively be formed on the top surface 45 of the cooling plate 40. The mounting surface 49 is the surface in which the fixing holes 50 are provided.

In this example, the recess 47 is cuboidal, having a first major side 51, a second major side 52, a first minor side 53, and a second minor side 54, the first and second major

- 11 sides 51, 52 being longer than the first and second minor sides 53, 54. In this example, the first and second major sides 51, 52 are parallel to each other, the first and second minor sides 53,54 are parallel to each other, and the first and second major sides 51, 52 are perpendicular to the first and second minor sides 53, 54.

The bottom surface 55 of the recess 47 is opposite to the backplate 7 of the power controller 4 (see FIG. 2) when the power controller 4 is attached to the cooling plate 40.

In this example, the cooling plate includes an inlet 56 and an outlet 57. The inlet 56 and outlet 57 are disposed in the first major side 41 of the cooling plate 40. The inlet 56 and the outlet 57 each have a conduit 62, 64 that extends into the cooling plate 40, beneath the recess 47. That is, the inlet conduit 62 and the outlet conduit 64 (see FIG. 9) extend in a planar direction from the major side of the cooling plate. In FIG. 7 only the conduit 62 of the inlet 56 is shown, but the outlet 57 includes a similar conduit 64 shown in

FIG. 9·

The cooling plate 40 also includes a first inlet hole 58 and a second inlet hole 59, each being formed in the bottom surface 55 of the recess 47 and connecting to the conduit 62 of the inlet 56. Similarly, a first outlet hole 60 and a second outlet hole 61 are formed in the bottom surface 55 of the recess 47 and connect the conduit of the outlet 57.

In the illustrated example the inlet 56, conduit 62, first inlet hole 58, and second inlet hole 59 are aligned with each other and are disposed proximate to a first minor side 53 (see FIG. 6) of the recess 47. The outlet 57, conduit, first outlet hole 60, and second outlet hole 61 are aligned with each other and are disposed proximate to the second minor side 54 of the recess 47. That is, the inlet 56 and outlet 57 are arranged at opposing ends of the bottom surface 55. The first inlet hole 58 and second inlet hole 59 are located at a first end of the recess 47, adjacent to the first minor side 53 of the recess

47. The first outlet hole 60 and the second outlet hole 61 are located at a second end of the recess 47, adjacent to the second minor side 54 of the recess 47.

In use, cooling fluid is provided to the inlet 56, passes into the cooling fluid chamber 48 via the conduit 62, first inlet hole 58 and second inlet hole 59, through the cooling fluid chamber 48, out of the first outlet hole 60, second outlet hole 61, conduit and the outlet

57- While the cooling fluid is in the cooling fluid chamber 48 it absorbs heat from the power controller 4, in particular via the backplate 7 and the protrusions 63 (see FIG. 8).

- 12 The cooling fluid carries the absorbed heat out of the outlet 57. The cooling fluid can then be passed through a cooler, for example a radiator or heat exchanger, before the cooling fluid is circulated back to the inlet 56. In this way, the power controller 4 is cooled and excess heat is dispersed.

As illustrated in FIG. 8 the backplate 7 of the power controller 4 includes protrusions 63 that extend from the backplate 7 into the cooling fluid chamber 48 and increase the surface area of the power controller 4 that is exposed to the cooling fluid chamber 48, thereby increasing heat transfer from the power controller 4 to the cooling fluid during use. The protrusions 63 are arranged in the same pattern as illustrated in FIG. 5. In particular, the protrusions 63 are arranged in columns and offset rows so that diagonal paths are defined between the protrusions 63.

The protrusions 63 are preferably integral to the backplate 7, but in alternative examples the protrusions 63 may be attached to the backplate 7, for example via a fastener or by welding. The backplate 7 and the protrusions 63 are preferably made from a material with high thermal conductivity. In a preferred example, the backplate 7 and protrusions 63 are made of a ceramic, but in other examples the backplate 7 and protrusions 63 are made of a metal, such as aluminium. In one example, the protrusions 63 are cylindrical pins. In another example, the protrusions 63 are conical. However, it will be appreciated that the protrusions 63 maybe any shape that increases the surface area of the backplate 7 that is exposed to cooling fluid during use.

Providing first and second inlet holes 58,59 and first and second outlet holes 60, 61 in the bottom surface 55 of the recess 47, which is opposite to the backplate 7 of the power controller 4 (see FIG. 2) during use, is advantageous because it creates two distinct flows of cooling fluid through the cooling fluid chamber 48. These different flows will generally not mix in the cooling fluid chamber 48, resulting in more even flow of cooling fluid through the cooling fluid chamber 48.

In particular, flow between the second inlet hole 59 and second outlet hole 61 prevents cooling fluid from the first inlet hole 58 from reaching the first major side 52 of the recess 47. Flow from the first inlet hole 58 to the second inlet hole 60 is thereby directed through the middle of the cooling fluid chamber 48, ensuring more even cooling across the backplate 7 of the power controller 4.

-13As illustrated in FIG. 9, when the power controller 4 is mounted to the cooling plate 40 the switching transistors 8, 9,10 are arranged above the cooling fluid chamber 48. In particular, the switching transistors 8, 9,10 are adjacent to each other and arranged in a line extending in the direction between the first minor side 53 of the recess 47 and the second minor side 54 of the recess 47. As cooling fluid moves from the first and second inlet holes 58, 59 to the first and second outlet holes 60, 61 excess heat is absorbed and carried with the cooling fluid through the outlet 57.

By providing first and second inlet holes 58, 59 and first and second outlet holes 60, 61 10 it has been found that cooling fluid flow through the cooling fluid chamber 48 is more even, and in particular that cooling fluid flows through the middle of the cooling fluid chamber 48, thereby eliminating the stagnant area that was previously described. Therefore, cooling is improved and the temperature gradient across the three switching transistors 8, 9,10 is reduced. In particular, arranging the first inlet hole 58, second inlet hole 59, first outlet hole 60, and second outlet hole 61 proximate to the corners of the recess 47, as illustrated, has been found to improve the flow of cooling fluid through the cooling fluid chamber 48, increasing cooling efficiency.

As illustrated in FIGS. 6, 7 and 9, the inlet conduit 62 and the outlet conduit 64 extend in a direction parallel to the bottom surface 55 of the recess 47, and the first and second inlet holes 58, 59 and first and second outlet holes 60, 61 extend perpendicularly from the bottom surface 55 of the recess 47 and intersect the conduits 62, 64. The first inlet hole 58 is arranged upstream of the second inlet hole 59 along the inlet conduit 62. Similarly, the first outlet hole 60 is arranged downstream of the second outlet hole 61 along the outlet conduit 64. In this context, upstream and downstream refer to the direction of the cooling fluid flow from the inlet 56 to the outlet 57. This arrangement means that the overall length of the cooling plate 40 in the direction of the first and second major dies 41, 42 is reduced in comparison to the arrangement illustrated in FIG. 3.

In preferred examples, the first inlet hole 58, second inlet hole 59, first outlet hole 60, and second outlet hole 61 are all circular. In this case, the size of these holes 58,59, 60, 61 is the area of the hole, which is a function of its diameter. In addition, the inlet 56, outlet 57, and the associated conduits 62, 64 are circular and the size of the inlet 56, outlet 57 and conduits 62, 64 is their cross-sectional area, which is a function of their

-14diameter. In preferred examples, the inlet 56 and outlet 57 have the same diameter and size as their respective conduits 62, 64.

In other examples, the first inlet hole 58, second inlet hole 59, first outlet hole 60, second outlet hole 61, inlet 56, outlet 57, and the conduits 62, 64 may be oval, square, rectangular, triangular, or any other shape, and in these cases the size is the crosssectional area.

In the illustrated preferred examples the first inlet hole 58, second inlet hole 59, first outlet hole 60, second outlet hole 61, inlet 56, outlet 57, and the conduits 62, 64 are all circular.

In some examples, the sizes of the second inlet hole 59 and the second outlet hole 61 are less than the sizes of the first inlet hole 58 and the first outlet hole 60. In this way, during use the majority of the cooling fluid flows between the first inlet hole 58 and the first outlet hole 60, while the flow of cooling fluid between the second inlet hole 59 and the second outlet hole 61 is at a greater velocity. The greater velocity of fluid flow between the second inlet hole 59 and the second outlet hole 61 can prevent fluid flowing between the first inlet hole 58 and the first outlet hole 60 from reaching the first major side 52 of the recess 47, thereby ensuring that cooling fluid moves through the middle of the cooling fluid chamber 48 to prevent stagnation of cooling fluid in this area.

In some examples, the size of the first inlet hole 58 is less than the size of the first outlet hole 60. This arrangement means that cooling fluid entering the cooling fluid chamber

48 through the first inlet hole 58 has a higher velocity than cooling fluid exiting the cooling fluid chamber 48 via the first outlet hole 60, which can improve flow of cooling fluid through the cooling fluid chamber 48.

In preferred examples, the first outlet hole 60 is the same size as the outlet conduit 64, so that there is minimal restriction to flow of cooling fluid out of the first outlet hole 60 to the outlet 57.

The positions of the first inlet hole 58, second inlet hole 59, first outlet hole 60, and second outlet hole 61 are described in relation to the first and second major sides 51,52 and first and second minor sides 53,54 of the recess 47. In particular, the spacing

-15between a hole 58,59, 60, 61 and a side 51, 52, 53,54 of the recess 47 in the distance between the centre of the hole 58,59, 60,61 and the side 51,52, 53, 54.

In some examples, the second inlet hole 59 and the second outlet hole 61 are spaced 5 from the second major side 52 of the recess 47 by a greater distance than the first inlet hole 58 and the first outlet hole 60 are spaced from the first major side 51 of the recess 47. This has been found to further improve flow of the cooling fluid between the second inlet hole 59 and the second outlet hole 61.

In some examples, the spacing between the second inlet hole 59 and the second major side 52 of the recess 47 may be greater than the spacing between the second outlet hole 61 and the second major side 52 of the recess 47. This has also been found to further improve flow of the cooling fluid flow between the second inlet hole 59 and the second outlet hole 61.

In some examples, the first and second inlet holes 58,59 are equally spaced from the first minor side 53 of the recess 47. Similarly, the first and second outlet holes 60, 61 are equally spaced from the second minor side 54 of the recess 47.

FIG. 10 illustrates a specific example of the present invention. Only the bottom surface of the recess 47 is shown, together with the first inlet hole 58, second inlet hole 59, first outlet hole 60 and second outlet hole 61.

In this particular example, the first inlet hole 58 and the second inlet hole 59 have different sizes. In addition, the first outlet hole 60 and the second outlet hole 61 have different sizes. In addition, the first inlet hole 58 and the first outlet hole 60 have different sizes.

In particular, the first inlet hole 58 is larger than the second inlet hole 59, and the first outlet hole 60 is larger than the second outlet hole 61. In particular, the size of the first inlet hole 58 is approximately four times of the size of the second inlet hole 59, and the size of the first outlet hole 60 is approximately four times the size of the second outlet hole 61. The second inlet hole 59 and the second outlet hole 61 are approximately the same size. The first outlet hole is approximately two times the size of the first inlet hole

58.

-ι6In addition, in this particular example the first inlet hole 58 and the first outlet hole 60 are spaced from the first major side 51 of the recess 47 by a distance that is between one and two times the width or diameter of the first outlet hole 60, more preferably approximately 1.3 times the diameter of the first outlet hole 60. In addition, in this particular example the second inlet hole 59 is spaced from the second major side 52 of the recess 47 by a distance that is between three and four times the width or diameter of the second inlet hole 59, more preferably approximately 3.6 times the diameter of the second inlet hole 59. In addition, in this particular example the second outlet hole 61 is spaced from the second major side 52 of the recess 47 by a distance that is between two and 4 times the width or diameter of the second outlet hole 61, more preferably approximately 3 times the diameter of the second outlet hole 61.

In this particular example, the recess 47 has a major length of approximately 145 mm and a minor length of approximately 65 mm. The first inlet hole 58 has a diameter of 7 mm, the second inlet hole 59 has a diameter of 5 mm, the first outlet hole 60 has a diameter of 10 mm, the second outlet hole 61 has a diameter of 5 mm, and the inlet 56, outlet 57 and conduits 62, 64 all have a diameter of 10 mm. The first inlet hole 58 and the first outlet hole 60 are spaced from the first major side 51 of the recess 47 by a distance of 13 mm. The second inlet hole 59 is spaced from the second major side 52 of the recess 47 by a distance of 18 mm. The second outlet hole 61 is spaced from the second major side 52 of the recess 47 by a distance of 15 mm.

Moreover, in particular examples the cooling fluid chamber has a depth of approximately 5-6 mm, as measured between the underside of the backplate 7 and the bottom surface 55 of the recess 47. It has been found that a cooling fluid flow of approximately 10 litres per minute advantageously cools the power controller 4.

It has been found that due to this arrangement a higher velocity flow is induced adjacent to the second major side 52 of the recess 47, between the second inlet hole 59 and second outlet hole 61, which also helps to direct cooling fluid that flows from the first inlet hole 58 to the first outlet hole 60 through the middle of the cooling fluid chamber 48, thereby eliminating stagnant areas. Moreover, placing the first and second inlet holes 58, 59 and first and second outlet holes 60, 61 proximate the corners of the cooling fluid chamber 48 prevents stagnant areas in the corners. Therefore, the described arrangement results in improved fluid flow and more even cooling across the power controller 4.

-17This is indicated in FIG. 11, which shows the bottom surface 55 of the recess 47 (see FIGS. 5 and 6), along with the protrusions 66 on the backplate 7 (see FIG. 8). During use the majority of the cooling fluid will flow from the first inlet hole 48 to the first outlet hole 60 because these holes 58, 60 are larger than the second inlet hole 59 and the second outlet hole 61. In addition, cooling fluid that flows from the second inlet hole 59 to the second outlet hole 61 moves at a greater velocity because of the smaller size of the second inlet hole 59 and the second outlet hole 61 relative to the first inlet hole 58 and the first outlet hole 60. It has been found that this higher velocity flow from the second inlet hole 59 to the second outlet hole 61 helps to direct the bulk of the cooling fluid flow between the first inlet hole 58 and first outlet hole 60 and prevents cooling fluid from the first inlet hole 58 reaching the second major side 52 of the recess. In particular, the higher velocity cooling fluid flow between the second inlet hole 59 and the second outlet hole 61 has been found to encourage fluid to flow through the middle of the cooling fluid chamber 48, thereby preventing stagnation in this area and ensuring even cooling fluid flow and even cooling across the backplate 7.

It will be appreciated that the cooling plate described above, in particular the size and arrangement of the first and second inlet holes 58, 59 and the first and second outlet holes 60, 61 can be scaled up or down so that a similar cooling plate can be used with power controllers of different sizes. Therefore, in general, the cooling plate 40 of the invention may have at least one of the following parameters:

• The size of the first outlet hole 60 is the same as the size of the outlet conduit 64 and outlet 57.

· The first outlet hole 60 is larger than the second inlet hole 58 and the second outlet hole 61. For example the size of the first outlet hole 60 maybe between

3.5 and 4.5 times the size of the second inlet hole 58 and the second outlet hole 61. In one example, the size of the first outlet hole 60 is approximately 4 times the size of the second inlet hole 58 and the second outlet hole 61.

· The first outlet hole 60 is larger than the first inlet hole 58. For example the size of the first outlet hole 60 maybe between 1.5 and 2.5 times the size of the first inlet hole 58. In one example, the size of the first outlet hole 60 is approximately 2 times the size of the first inlet hole 58.

FIG. 12 shows a further example cooling plate 40, having the recess 47 that forms the cooling fluid chamber 48, as described above. In this example, the cooling plate 40

-18further includes a heat sink 65. As shown, the cooling plate 40 is elongated in the direction of the first and second minor sides 43, 44 of the cooling plate 40, and the recess 47 is formed towards the second major side 42 of the cooling plate 40. The extended part of the cooling plate 40 provides a heat sink 65. The inlet 56 and the outlet 57 are formed in the first major side 41 of the cooling plate 40, and the associated conduits 62, 64 extend through the heat sink 65 to the recess 47. The cooling plate 40 is preferably made from a thermally conductive material, for example a metal such as aluminium. In this way, excess heat from the power controller 4 (see FIG. 2) is drawn into the heat sink 65, which further improves the operating temperature of the power controller 4.

In some examples, the cooling plate 40 is a part of an enclosure that surrounds the power controller 4. For example, the enclosure may include a cooling plate 40 to which the power controller 4 is attached, and a cover that covers the power controller 4.

The cooling system may further include a pump that circulates the cooling fluid through the cooling fluid chamber 48. The pump can be connected to the inlet 56 and optionally also to the outlet 57. The cooling fluid may be a liquid, for example water, Polyalkylene glycol, or hydrocarbon based coolants such as Opticool and other specifically engineered fluids. The cooling fluid may include additives, for example corrosion inhibitors. Alternatively, the cooling fluid may be a gas, for example air, nitrogen, or carbon dioxide.

The embodiments of the invention shown in the drawings and described above are exemplary⁷ embodiments only and are not intended to limit the scope of the invention, which is defined by the claims hereafter. It is intended that any combination of nonmutually exclusive features described herein are within the scope of the present invention.

Claims

Claims

1. A cooling plate for an electronic power controller, the cooling plate comprising: a recess and a mounting surface arranged such that said electronic power controller is attachable to the mounting surface to cover the recess and form a cooling 5 fluid chamber, the recess having an opposing surface that is facing said electronic power controller when said electronic power controller is attached to the mounting surface;

a first inlet hole and a second inlet hole disposed in the opposing surface of the recess; and, io a first outlet hole and a second outlet hole disposed in the opposing surface of the recess;

and wherein, during use, cooling fluid enters the cooling fluid chamber via first inlet hole and second inlet hole and exits the cooling fluid chamber via the first outlet hole and second outlet hole.
2. The cooling plate of claim l, wherein the recess comprises a first end and a second end, the second end being opposite the first end, and wherein the first inlet hole and second inlet hole are disposed adjacent the first end of the cooling fluid chamber, and the first outlet hole and second outlet hole are disposed adjacent the second end of

20 the cooling fluid chamber.
3. The cooling plate of claim l or claim 2, wherein the recess is rectangular and comprises first and second major sides and first and second minor sides, the first and second major sides having a greater length than the first and second minor sides.
4. The cooling plate of claim 3, wherein the first inlet hole and the second inlet hole are disposed adjacent the first minor side of the recess, and the first outlet hole and the second outlet hole are disposed adjacent the second minor side of the recess.

30
5. The cooling plate of claim 3, wherein each of the first inlet hole, second inlet hole, first outlet hole, and second outlet hole is disposed adjacent a different corner of the bottom surface of the recess.
6. The cooling plate of any of claims 3, 4 or 5, wherein the first inlet hole and

35 second inlet hole are equidistant from the first minor side wall of the recess, and the

- 20 first outlet hole and second outlet hole are equidistant from the second minor side wall of the recess.
7. The cooling plate of claims 3 to 6, wherein the first inlet hole and the first outlet 5 hole are equidistant from the first major side of the recess.
8. The cooling plate of any of claims 3 to 7, wherein the second inlet hole is spaced from the second major side of the recess by a greater distance than the second outlet hole is spaced from the second major side of the recess.
9. The cooling plate of any of claims 3 to 8, wherein a spacing between the first outlet hole and the second outlet hole is greater than a spacing between the first inlet hole and the second inlet hole.

15 10. The cooling plate of any preceding claim, wherein the second inlet hole and the second outlet hole are arranged such that during use cooling fluid flowing between the second inlet hole and second outlet hole does not mix with fluid flowing between the first inlet hole and first outlet hole.

20 11. The cooling plate of any preceding claim, wherein the first inlet hole is larger than the second inlet hole, and wherein the first outlet hole is larger than the second outlet hole.

12. The cooling plate of any preceding claim, wherein the first inlet hole is larger

25 than the second inlet hole.

13. The cooling plate of claim 12, wherein the size of the first inlet hole is between 3 and 5 times the size of the second inlet hole.

30 14. The cooling plate of claim 13, wherein the size of the first inlet hole is approximately 4 times of the size of the second inlet hole.

15. The cooling plate of any preceding claim, wherein the first outlet hole is larger than the second outlet hole.

- 21 16. The cooling plate of claim 15, wherein the size of the first outlet hole is between 3 and 5 times the size of the second outlet hole.

17. The cooling plate of claim 15, wherein the size of the first outlet hole is 5 approximately 4 times the size of the second outlet hole.

18. The cooling plate of any preceding claim, further comprising an inlet conduit that is in fluid communication with the first inlet hole and the second inlet hole.
10 19. The cooling plate of claim 18, wherein the inlet conduit is arranged such that the second inlet hole is downstream of the first inlet hole when cooling fluid flows through the inlet conduit during use.

20. The cooling plate of claim 18 or claim 19, wherein the size of the inlet conduit is
15 greater than the size of the second inlet hole.

21. The cooling plate of any of claims 18 to 20, wherein the size of the inlet conduit is greater than the size of the first inlet hole.
20 22. The cooling plate of any of claims 18 to 21, wherein the inlet conduit extends through the cooling plate in a direction parallel to the opposite surface of the recess.
23. The cooling plate of any preceding claim, further comprising an outlet conduit that is in fluid communication with the first outlet hole and the second outlet hole.
24. The cooling plate of claim 23, wherein the outlet conduit is arranged such that the first outlet hole is downstream of the second outlet hole when cooling fluid flows into the outlet conduit via the first outlet hole and second outlet hole.

30 25. The cooling plate of claim 23 or claim 24, wherein the size of the outlet conduit is greater than the size of the second outlet hole.

26. The cooling plate of any of claims 23 to 25, wherein the size of the first outlet hole is approximately equal to the size if the outlet conduit.

- 22 27- The cooling plate of any of claims 23 to 26, wherein the outlet conduit extends through the cooling plate in a direction parallel to the opposite surface of the recess.

28. The cooling plate of any preceding claim, wherein the cooling plate is made of a 5 ceramic.

29. The cooling plate of any preceding claim, further comprising a heat sink.

30. A cooling system for an electronic power controller, the cooling system

10 comprising the cooling plate of any preceding claim and a pump arranged to circulate cooling fluid through the cooling fluid chamber via the first inlet hole, second inlet hole, first outlet hole, and second outlet hole.

31. An electronic power control assembly comprising a cooling plate according to

15 any of claims 1 to 29 and an electronic power controller attached to the cooling plate.

32. The electronic power control assembly of claim 31, wherein the electronic power controller comprises a backing plate and a plurality of switching transistors mounted to the backing plate.

33. The electronic power control assembly of claim 32, wherein the backing plate comprises a plurality of protrusions that are arranged to protrude into the cooling fluid chamber when the electronic power controller is attached to the cooling plate.
25 34· The electronic power control assembly of claim 33, wherein the plurality of protrusions are conical.

35. The electronic power control assembly of claim 33 or claim 34, wherein the plurality of protrusions extend at least 75% of the distance across the recess towards the
30 opposing surface.

36. The electronic power control assembly of any of claims 33 to 35, wherein the protrusions are arranged in columns and offset rows.
35 37· The electronic power control assembly of any of claims 31 to 36, comprising three power controllers arranged adjacently in a line.

-2338. The electronic power control assembly of any of claims 31 to 37, wherein the electronic power controller comprises a high power switch adapted to output power for an electric motor.
39. The electronic power control assembly of claim 38, wherein the electronic power controller comprises a metal-oxide-semiconductor field-effect transistor, or an insulated-gate bipolar transistor.

10
40. A vehicle comprising the electronic power control assembly of any of claims 31 to 39·
41. The vehicle of claim 40, further comprising an electric motor arranged to provide a driving force for the vehicle.
42. The vehicle of claim 40 or claim 41, wherein the vehicle is an electric, hybrid, or range-extended vehicle.

Intellectual

Property

Office

Application No: GB1703650.0