Hybrid cooling system for axial flux switched permanent magnet machine

Abstract

The application discloses a hybrid cooling system of an axial flux switched permanent magnet motor, and relates to the technical field of motor cooling. The hybrid cooling system comprises a stator casing, a stator with salient pole structure, a rotor and high-thermal-conductivity potting glue in the casing. The motor stator comprises a U-shaped stator core, permanent magnets and concentrated armature windings. The permanent magnets and the stator core are coaxially and alternately arranged along a circumference. The high-thermal-conductivity potting glue is filled in a cavity between the stator end and the stator casing. Cooling channels are arranged in the stator casing and the high-thermal-conductivity potting glue. The permanent magnets are segmented, and heat conduction sheets are arranged between the segments. The heat conduction sheets are embedded into the stator casing, and heat generated by stator side iron loss, eddy current loss and copper loss is removed. Direct contact heat exchange between the circumferential cooling channels and the concentrated armature windings can improve the cooling efficiency of the motor. The hybrid cooling mode of the heat conduction sheet, the potting glue and liquid cooling solves the technical problem of difficult heat dissipation of the stator side of the axial flux switched permanent magnet motor.

Description

Technical Field

[0001] This invention relates to the field of motor cooling technology, and in particular to a hybrid cooling system for an axial flux switching type permanent magnet motor. Background Technology

[0002] Axial flux-switching permanent magnet motors offer advantages such as small axial dimensions, high efficiency and power density, and simple structure, making them suitable for applications with stringent requirements regarding size, weight, and reliability, including wind power generation, electric vehicles, and aerospace. However, the stator side of this motor comprises permanent magnets, a centralized armature winding, and a stator core, resulting in a very compact structure. During operation, eddy current losses from the permanent magnets, iron losses from the stator core, and copper losses from the centralized armature winding are all concentrated on the stator side. This compact stator structure and high loss density can lead to heat dissipation difficulties, potentially causing high-temperature demagnetization of the permanent magnets and aging of the winding insulation. This is a major factor limiting its application.

[0003] With current technology, the heat generated by the rotor core of an axial flux-switching permanent magnet motor is dissipated through the air gap. The heat generated by the stator windings in the slots is transferred to the stator core and then to the housing through the air in the slots. The heat generated by the outer and inner diameter winding ends is transferred to the housing through the air surrounding the end windings. The heat generated by the permanent magnets is dissipated through the stator core and then to the housing. Natural air cooling relies on the rotor rotation to drive the internal air gap, forming convection heat transfer. However, due to the low thermal conductivity of the air inside the motor and its weak heat transfer capacity, the heat dissipation efficiency of this self-ventilation effect is limited, and it is only suitable for low-power motors with small rotor temperature rise. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a hybrid cooling system for an axial flux switching permanent magnet motor. This system uses a hybrid cooling method of "heat-conducting sheet + potting compound + liquid cooling" to cool the permanent magnet, stator core, and stator centralized armature winding, thus solving the problem of concentrated heat source and difficult heat dissipation on the stator side.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A hybrid cooling system for an axial flux-switching permanent magnet motor includes a stator housing, two stators with salient pole structures, a rotor, and a highly thermally conductive potting compound. The stator housing contains a spiral cooling channel. The stator comprises a U-shaped stator core, permanent magnets, and a concentrated armature winding. The permanent magnets and stator core are coaxially and alternately placed around the circumference. The permanent magnets are magnetized circumferentially, with adjacent permanent magnets magnetized in opposite directions. Corresponding permanent magnets on the two stators are magnetized in opposite directions. Each group of permanent magnets is divided into n segments, and a single coil is wound around the teeth formed by adjacent stator core teeth and embedded permanent magnets. The stator consists of a rotor disc and a rotor core. The stator and rotor share the same axis, and there is a certain air gap between them. High thermal conductivity heat-conducting plates are embedded in the segmented permanent magnets. The sides of the heat-conducting plates are tightly attached to the permanent magnets, and the bottom is embedded in the stator housing. The heat generated by the permanent magnets is transferred to the stator housing through the heat-conducting plates and carried away by the cooling medium in the spiral cooling channel. The stator core is tightly attached to the stator housing. There is a high thermal conductivity potting compound in the cavity between the stator end and the stator housing. The high thermal conductivity potting compound has a surrounding cooling channel, which allows the cooling medium to flow in the high thermal conductivity potting compound and carry away the heat generated by the windings.

[0007] Furthermore, the permanent magnets embedded between the two "U"-shaped stator cores are segmented, using n permanent magnets separated by radial equal gaps, with the same size gap between each permanent magnet, that is, each group of n permanent magnets has (n-1) such gaps; a heat-conducting plate is embedded in each gap, with the heat-conducting plate tightly attached to the permanent magnet on both sides, and the bottom is embedded in the stator housing, forming a heat transfer channel from the permanent magnet to the stator housing.

[0008] Furthermore, the side of the stator housing is in close contact with the heat-conducting plate embedded in the gap of the permanent magnet, and the inside of the stator housing is in close contact with the high thermal conductivity potting compound that is filled in the cavity of the inner and outer diameter of the stator. A spiral cooling channel is opened inside the stator housing, and the heat transferred from the heat-conducting plate and the high thermal conductivity potting compound is carried away by the flow of the cooling medium.

[0009] Furthermore, a high thermal conductivity potting compound fills the cavity between the centralized armature winding and the stator housing, and a ring-shaped cooling channel is formed within the high thermal conductivity potting compound, surrounding the centralized armature winding in a circular shape.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] 1. The permanent magnets are placed in radially spaced segments with heat-conducting plates inserted between the segments, so that the heat generated by the permanent magnets can be transferred to the housing through the heat-conducting plates to cool the permanent magnets.

[0012] 2. A spiral cooling channel is opened inside the stator housing. The bottom of the stator core, the permanent magnet, and the bottom of the heat-conducting plate that is in close contact with the side of the permanent magnet are all tightly attached to the stator housing. The heat generated by the iron loss of the stator core and the eddy current loss of the permanent magnet is transferred into the housing and carried away by the flow of the cooling medium in the cooling channel inside the housing.

[0013] 3. High thermal conductivity potting compound is injected into the cavity between the inner side of the housing and the stator end. The high thermal conductivity potting compound can quickly conduct heat generated by the centralized armature winding and stator core in contact with it. A surrounding cooling channel is pre-formed in the high thermal conductivity potting compound, and the cooling medium flows in the cooling channel to carry away the heat absorbed by the high thermal conductivity potting compound.

[0014] 4. This cooling system is suitable for axial flux switching permanent magnet motors where both the permanent magnet and armature winding are located on the stator side. Since there are neither permanent magnets nor windings on the rotor, the structure is simple and robust. Compared with motors where the permanent magnet is on the rotor, this cooling system can improve the heat dissipation effect of the permanent magnet. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the segmented placement of permanent magnets in a hybrid cooling system for an axial flux switching permanent magnet motor according to the present invention.

[0016] Figure 2 This is a cross-sectional view of the stator housing in a hybrid cooling system of an axial flux switching permanent magnet motor according to the present invention.

[0017] Figure 3 This is a cross-sectional view of the high thermal conductivity potting compound in the hybrid cooling system of an axial flux switching permanent magnet motor according to the present invention;

[0018] Figure 4 This is an exploded view of a hybrid cooling system for an axial flux-switching permanent magnet motor.

[0019] In the diagram: 1 is the stator housing, 2 is the heat-conducting plate, 3 is the permanent magnet, 4 is the centralized armature winding, 5 is the stator core, 6 is the high thermal conductivity potting compound, 7 is the rotor core, 8 is the rotor disc, 9 is the first inlet of the housing, 10 is the first outlet of the housing, 11 is the second inlet of the housing, 12 is the second outlet of the housing, 13 is the spiral cooling channel, and 14 is the surrounding cooling channel. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] An exploded view of a hybrid cooling system for an axial flux-switching permanent magnet motor is shown below. Figure 4 As shown, there is a pair of stators, which are placed coaxially opposite each other and have a salient pole structure. The stator winding adopts a concentrated armature winding (4). There are "U"-shaped stator cores (5) distributed in a circle on the stator, which are wrapped by the stator housing (1). Permanent magnets (3) are embedded between adjacent "U"-shaped stator cores (5). The rotor with a salient pole structure is placed coaxially between the two stators and is composed of a rotor disk (8) and a rotor core (7). The direction of the magnetic field in the motor is axial.

[0022] Figure 1 This is a schematic diagram of the segmented placement of permanent magnets (3) in this invention. A set of n permanent magnets (3) with equal spacing along the radial direction are embedded between adjacent "U"-shaped stator cores (5), so that there is a gap between each permanent magnet (3). There are (n-1) such gaps in a set of n permanent magnets. (n-1) heat-conducting plates (2) are inserted into the (n-1) gaps respectively. The side of the heat-conducting plate (2) is in close contact with the side of the permanent magnet (3).

[0023] Figure 2 This is a cross-sectional view of the stator housing (1) in this invention. The stator housing (1) has a first housing inlet (9) and a first housing outlet (10) on its side. The first housing inlet (9) and the first housing outlet (10) extend into the spiral cooling channel (13) inside the stator housing (1). The cooling medium enters the spiral cooling channel (13) through the second housing inlet (11). The cooling medium flows in the cooling channel and carries away the heat absorbed by the stator housing (1). It flows out through the second housing outlet (12). The front of the stator housing (1) has a second housing inlet (11) and a second housing outlet (12). The second housing inlet (11) and the second housing outlet (12) extend through the upper part of the stator housing (1) into the surrounding cooling channel (14) inside the high thermal conductivity potting compound (6). The permanent magnet inter-segment heat-conducting sheet (2) is in close contact with the stator housing (1).

[0024] Figure 3This is a cross-sectional view of the high thermal conductivity potting compound in this invention. The cavity between the stator end and the inner side of the stator housing (1) is filled with high thermal conductivity potting compound (6), and a surrounding cooling channel (14) is formed in the high thermal conductivity potting compound (6). The surrounding cooling channel (14) is made after the stator winding is completed. The shape and size of the water-soluble material pipe are determined according to the size of the centralized armature winding (4) and the cavity around the winding. After the water-soluble material pipe is fixed in the corresponding position of the centralized armature winding (4), the potting operation is performed. After the potting compound is completely cured, the water-soluble material is dissolved to obtain the required surrounding cooling channel (14), which is surrounded on the outside of the stator centralized armature winding (4). The cooling medium enters the high thermal conductivity potting compound (6) through the second inlet (11) of the housing and flows into the surrounding cooling channel (14). The cooling medium flows in the cooling channel and carries away the heat absorbed by the high thermal conductivity potting compound (6), and flows out through the second outlet (12) of the housing.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hybrid cooling system for an axial flux-switching permanent magnet motor, characterized in that: The motor includes a stator housing (1), two stators with salient pole structures, a rotor, and a high thermal conductivity potting compound (6); the stator housing (1) is provided with a spiral cooling channel (13); the stator includes a "U"-shaped stator core (5), permanent magnets (3), and a concentrated armature winding (4). The permanent magnets (3) and the stator core (5) are placed alternately along the circumference, and the permanent magnets (3) are magnetized in the circumferential direction. The magnetization directions of adjacent permanent magnets (3) are opposite. The two stators are phase-dependent. The permanent magnets (3) at corresponding positions are magnetized in opposite directions. Each group of permanent magnets (3) is divided into n segments. A single coil is wound around the teeth formed by the adjacent stator core and the embedded permanent magnets (3). The rotor is composed of a rotor disk (8) and a rotor core (7). The stator and rotor have the same axis, and there is a certain air gap between the stator and rotor. The segmented permanent magnets (3) are embedded with heat-conducting plates (2) with high thermal conductivity. The sides of the heat-conducting plates (2) are tightly attached to the permanent magnets (3), and the bottom is embedded in the stator housing. 1) The heat generated by the permanent magnet (3) is transferred to the stator housing (1) through the heat-conducting plate (2), and carried away by the cooling medium in the spiral cooling channel (13); the stator core (5) is tightly attached to the stator housing (1); there is a high thermal conductivity potting compound (6) in the cavity between the stator end and the stator housing (1), and there is a surrounding cooling channel (14) in the high thermal conductivity potting compound (6), so that the cooling medium flows in the high thermal conductivity potting compound (6) to carry away the heat generated by the winding. The permanent magnet (3) between the two embedded "U"-shaped stator cores (5) is segmented, using n permanent magnets separated by radial equal gaps. Each permanent magnet (3) has a gap of the same size, that is, each group of n permanent magnets has (n-1) such gaps. A heat-conducting plate (2) is embedded in each gap. The heat-conducting plate (2) is tightly attached to the permanent magnet (3) on both sides, and the bottom is embedded in the stator housing (1), forming a heat transfer channel from the permanent magnet (3) to the stator housing (1).

2. The hybrid cooling system for an axial flux switching permanent magnet motor according to claim 1, characterized in that: The side of the stator housing (1) is tightly fitted with the heat-conducting plate (2) embedded in the gap of the permanent magnet (3), and the inside of the stator housing (1) is in close contact with the high thermal conductivity potting compound (6) that is filled in the cavity of the inner and outer diameter of the stator. A spiral cooling channel (13) is opened inside the stator housing (1) to carry away the heat transferred from the heat-conducting plate (2) and the high thermal conductivity potting compound (6) through the flow of the cooling medium.

3. The hybrid cooling system for an axial flux switching permanent magnet motor according to claim 1, characterized in that: High thermal conductivity potting compound (6) fills the cavity between the centralized armature winding (4) and the stator housing (1), and a ring-shaped cooling channel (14) is opened in the high thermal conductivity potting compound (6) to surround the centralized armature winding (4) in a circular shape.

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