Oil-cooled permanent magnet motor

Abstract

The application discloses an oil-cooled permanent magnet motor, which comprises a stator, a rotor, bearings, end covers and an oil cooling system, the stator comprises a stator frame, a stator core and a stator coil, the rotor comprises a rotor support and a rotor permanent magnet, the bearings comprise driving end bearings and non-driving end bearings, the end covers comprise driving end end covers and non-driving end end covers, and the oil cooling system comprises an oil pump, oil conveying pipelines and oil cooling channels; each component forms a circulating oil-cooled permanent magnet motor; the stator core yoke part oil cooling channels are arranged at positions close to tooth bottoms of the stator core; and the stator-rotor air gap oil cooling channels are arranged at stator-rotor air gaps; the oil-cooled permanent magnet motor can realize self-lubrication of the bearings and does not need to be separately supplied with oil, thus better solving the problems of uneven stator temperature, rotor cooling difficulty and bearing lubrication and cooling of the high-power-density permanent magnet motor, and the motor has the advantages of compact overall structure, high cooling efficiency, good reliability, simple process, easy realization, low cost and improved product market competitiveness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of motor cooling, and particularly relates to an oil-cooled permanent magnet motor. BACKGROUND

[0002] Permanent magnet motors have the advantages of simple mechanism, reliable operation, low loss, high efficiency, and direct drive control, and are widely used in various industrial fields such as ship propulsion, mining, metallurgical rolling, and wind power generation. In order to meet the requirements of different application environments and different driving loads, higher requirements are put forward for the size and weight of the motor, and therefore the electromagnetic thermal load of the motor is also increasingly high, that is, the power density of the motor is increasingly high.

[0003] Underwater motors are mainly used in underwater equipment such as submersibles, underwater robots, and deep-sea space stations, and are the power source of various underwater equipment. The key to the design of underwater motors is to cope with environmental factors such as high pressure, strong corrosion, and low temperature under water. In addition, since the underwater motor needs to operate underwater, it also needs to ensure excellent sealing performance. Compared with motors working in air, since the underwater motor works in a special environment at a certain depth underwater, the motor generally adopts the method of filling oil to balance the external pressure, but when the motor rotor rotates, additional fluid friction loss will be generated. In addition, underwater motors are usually required to have small size and large power density, which makes the loss generated per unit volume larger. The motor loss is large, and the temperature rise of each component is high, which not only affects the performance and service life of the motor, but also damages the insulation layer of the motor, so the cooling of the underwater motor is very important.

[0004] Traditional underwater motors are usually filled with internal oil, and the internal oil is not circulated. The motor cooling is performed by relying on the water-cooled motor shell to dissipate heat, and a complex water-cooled system needs to be configured. The heat source of the motor is far away from the cold source, the cooling path has large thermal resistance, the temperature drop in the motor is large, the temperature rise of the motor winding and other components is high, and the temperature distribution in the motor is uneven. In addition, the bearing also needs to be designed with a special cooling system.

[0005] The existing new energy vehicles more and more adopt oil-cooled motors for direct cooling. Since the oil itself has the characteristics of not being magnetically conductive and not being electrically conductive, the cooling method of directly contacting the cooling oil with the motor heat generating components greatly improves the cooling efficiency of the motor, and greatly improves the power density of the motor.

[0006] The existing oil cooling technology mostly uses a spraying cooling method to cool the stator end winding, and the cooling oil is directly sprayed to the winding end through a spray head, and the oil is distributed to other positions under the action of gravity, and a large amount of heat is taken away instantaneously. This method has obvious cooling effect, but the design of the stator end spray head is complex, is greatly affected by gravity and rotation of the rotor, and is easy to cause uneven cooling, and the temperature difference of the windings at different positions is large, which affects the overall cooling effect. The cooling of the stator core part is generally arranged on the outer surface of the stator core or in the stator core, and the cooling effect is poor due to the long heat conduction path.

[0007] In order to solve the above problems, many new energy automobile motors currently adopt an immersion type oil cooling scheme, for example, the invention patent 2023104501104.1 aims at the heat dissipation problems of the motor slot winding, end winding and stator core, and proposes an oil cooling solution, which realizes direct cooling of the slot winding through the internal multi-path cooling oil channel of the stator core, greatly improves the overall cooling effect, but has problems of complex structure, high requirement on manufacturing process, etc., and the stator punching yoke hole area is located in the main magnetic path part of the core, which greatly affects the magnetic field distribution of the core yoke part, and the saturation of the local magnetic field greatly limits the improvement of the overall performance of the motor.

[0008] Therefore, a stator cooling scheme for a permanent magnet motor is needed to further improve the power density of the oil-cooled permanent magnet motor. SUMMARY

[0009] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide an oil-cooled permanent magnet motor to solve the problems of uneven temperature of motor winding, difficulty in cooling the rotor and lubrication and cooling of the bearing.

[0010] The technical scheme adopted by the present application to solve its technical problems is: an oil-cooled permanent magnet motor, comprising a stator, a rotor, a bearing, an end cover and an oil cooling system; the stator part comprises a stator base, a stator core and a stator coil; the rotor part comprises a rotor support and a rotor permanent magnet; the bearing comprises a driving end bearing and a non-driving end bearing; the end cover comprises a driving end cover and a non-driving end cover; the oil cooling system comprises an oil pump, an oil supply pipeline and an oil cooling channel; each component forms a circulating oil-cooled permanent magnet motor, which can realize balanced cooling of the stator coil, rotor permanent magnet and bearing of the permanent magnet motor, and the cooling oil also plays a lubricating role for the rotor bearing, realizing self-lubrication of the bearing, and separate oil supply is not needed; the oil cooling channel is composed of a stator core yoke oil cooling channel arranged near the tooth bottom of the stator core and a stator-rotor air gap oil cooling channel arranged at the stator-rotor air gap.

[0011] The stator core yoke oil cooling channel of the oil-cooled permanent magnet motor is directly formed when the core punching is punched, and the shape of the channel hole is circular, square or waist-round.

[0012] Further, when the stator core is a whole round punching sheet, the total number of the passage holes n1 has no coupling relationship with the number of the stator slots N.

[0013] Further, when the stator core is a fan-shaped punching sheet, the total number of the passage holes n1=n×a×b, a is the number of the fan-shaped sheets, b is the number of the fan-shaped sheet overlaps, n is a natural number 1, 2, 3…, and n1≤N is ensured, N is the number of the stator slots.

[0014] Further, the inner circle of the passage hole is designed to have a micro flow channel according to the cooling efficiency, and the width or inner diameter of the micro flow channel is 0.5-1mm.

[0015] The oil-cooled permanent magnet motor has a stator-rotor air gap oil cooling channel which is a stator-rotor air gap, and the radial length and axial length of the stator-rotor air gap oil cooling channel are determined by electromagnetic design.

[0016] Compared with the prior art, the above technical scheme of the present application has the following technical effects:

[0017] 1. The present application adopts the cooling method of arranging the oil cooling channels at the tooth root of the stator core yoke and the stator-rotor air gap, and this cooling scheme has high cooling efficiency, greatly shortens the conduction distance of the motor stator coil and the core and the cold source, and is beneficial to the temperature balance of the motor stator winding and improves the reliability of the insulation.

[0018] 2. The arrangement of the stator-rotor air gap oil cooling solves the cooling problem of the permanent magnet motor rotor permanent magnet, and is beneficial to the further improvement of the power density of the permanent magnet motor.

[0019] 3. The motor is filled with oil, and the rotor bearing does not need to be separately supplied with oil and can realize self-lubricating operation.

[0020] 4. The stator yoke oil cooling channel can be formed at one time when the motor stator punching sheet is punched, and the process is simple and the reliability is high. DETAILED DESCRIPTION

[0021] Figure 1 is a general structure sectional view of the present application;

[0022] Figure 2 is a schematic diagram of the cooling system of the present application;

[0023] Figure 3 is a schematic diagram of the passage hole shape of the present application which is a circle;

[0024] Figure 4 is a schematic diagram of the passage hole shape of the present application which is a square.

[0025] The reference signs are: 1 - stator, 2 - rotor, 2.1 - rotor support, 2.2 - rotor permanent magnet, 3 - bearing, 3.1 - driving end bearing, 3.2 - non-driving end bearing, 4 - end cover, 4.1 - driving end end cover, 4.2 - non-driving end end cover, 5 - oil cooling system, 5.1 - oil pump, 5.2 - oil delivery pipeline, 5.3 - oil cooling channel, 5.3.1 - stator core yoke part oil cooling channel, 5.3.2 - stator-rotor air gap oil cooling channel. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Referring to Figure 1 , Figure 2 The oil-cooled permanent magnet motor of the embodiments of the present application mainly consists of a stator 1, a rotor 2, a bearing 3, an end cover 4 and an oil cooling system 5. The stator part includes a stator frame 1.1, a stator core 1.2 and a stator coil 1.3; the rotor part includes a rotor support 2.1 and a rotor permanent magnet 2.2; the bearing 3 includes a driving end bearing 3.1 and a non-driving end bearing 3.2; the end cover 4 includes a driving end end cover 4.1 and a non-driving end end cover 4.2; the oil cooling system includes an oil pump 5.1, an oil delivery pipeline 5.2 and an oil cooling channel 5.3, and each component forms a circulating oil-cooled permanent magnet motor, which can realize balanced cooling of the stator coil 1.3, the rotor permanent magnet 2.2 and the bearing 3 of the permanent magnet motor, and the cooling oil also plays a lubricating role for the rotor bearing 3, realizing self-lubrication of the bearing 3 without separate oil supply. The oil cooling channel 5.3 is composed of two parts: the stator core 1.2 is arranged with a stator core yoke part oil cooling channel 5.3.1 of a certain shape near the tooth bottom position, and a stator-rotor air gap oil cooling channel 5.3.2 is arranged at the stator-rotor air gap.

[0028] The stator core yoke oil cooling channel 5.3.1 distributed in the core yoke is directly formed when the core punching is punched, if the stator core is a whole circle punching, the number n1 of holes and the number N of slots do not constitute a strong constraint, if the stator core is a sector punching, the number n1 of holes and the number N of slots have a coupling relationship (the sector number a, the overlap number b and the slot number N have a coupling relationship), the total number n1 of channel holes is n×a×b, a is the sector number, b is the sector overlap number, n is a natural number 1, 2, 3…, and n1≤N is ensured. The shape of the channel hole is circular, square or waist round. The radial positioning R1 of the channel hole is determined according to electromagnetic design calculation; the area size and number of the hole are determined according to the oil amount distribution of the two / three parallel cooling channels. The inner circle of the hole is provided with a micro channel according to the cooling efficiency design, the cross section of the micro channel is circular or rectangular, the inner diameter or width is 0.5-1mm, and the micro channel structure in the hole can significantly enhance the internal disturbance of the flow channel, improve the flow Reynolds number and enhance the heat exchange capacity.

[0029] In the preferred embodiment of the application, the radial positioning of the stator core yoke oil cooling channel 5.3.1 is determined according to electromagnetic design calculation, and the local magnetic density does not exceed the saturation point of the stator core; the cross-sectional area A1 and the number n1 of holes are determined according to the oil amount distribution of the two parallel cooling channels.

[0030] Referring to Figure 3 As shown in the figure, the stator core yoke oil cooling channel 5.3.1 of the embodiment 1 scheme of the application is located at the tooth root of the stator core, the inner circle of the hole is provided with a micro channel, the convective heat transfer area is significantly increased compared with the traditional scheme, the internal fluid disturbance of the flow channel can be enhanced, the heat exchange is strengthened, and the cooling efficiency of the stator core yoke is greatly improved.

[0031] Referring to Figure 4 As shown in the figure, the stator core yoke oil cooling channel 5.3.1 of the embodiment 2 scheme of the application is located at the tooth root of the stator core, is square, and the inner circle of the hole is provided with a micro channel, the convective heat transfer area is significantly increased compared with the traditional scheme, the internal fluid disturbance of the flow channel can be enhanced, the heat exchange is strengthened, and the cooling efficiency of the stator core yoke is greatly improved.

[0032] The stator-rotor air gap oil cooling channel 5.3.2 is the stator-rotor air gap, and the radial length and the axial length are determined by electromagnetic design.

[0033] The oil-cooled permanent magnet motor of the application can solve the problems of uneven temperature of the stator slot winding and end winding, cooling difficulty of the core and the rotor permanent magnet and bearing lubrication and cooling of the current high-power-density permanent magnet motor, further improve the cooling efficiency and reliability of the motor. Since the water cooling system or cooling fan is cancelled, the overall motor is compact, the volume and weight of the motor can be further reduced, and the power density is improved.

[0034] The application has great degree of innovation in improving motor power density, improving motor reliability, reducing cost and the like, and is particularly suitable for use in high-power-density, low-speed, compact-structure, high-reliability required ship propulsion motor or industrial low-speed permanent magnet direct-drive motor.

[0035] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that; it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An oil-cooled permanent magnet motor, comprising a stator (1), a rotor (2), a bearing (3), an end cover (4) and an oil cooling system (5); the stator (1) comprises a stator frame (1.1), a stator core (1.2) and a stator coil (1.3); the rotor (2) comprises a rotor support (2.1) and a rotor permanent magnet (2.2); the bearing (3) comprises a drive end bearing (3.1) and a non-drive end bearing (3.2); the end cover (4) comprises a drive end cover (4.1) and a non-drive end cover (4.2); the oil cooling system (5) comprises an oil pump (5.1), an oil pipeline (5.2) and an oil cooling channel (5.3), and is characterized in that: The oil cooling channel (5.3) is composed of a stator core yoke oil cooling channel (5.3.1) arranged near the tooth bottom of the stator core and a stator-rotor air gap oil cooling channel (5.3.2) arranged at the stator-rotor air gap, and each part constitutes a circulating oil cooling permanent magnet motor.

2. An oil-cooled permanent magnet electric machine according to claim 1, characterized in that, When the stator core (1.2) is a fan-shaped punching sheet, the total number of the channel holes is n1=n×a×b, a is the number of fan-shaped sheets, b is the number of fan-shaped sheet overlaps, n is a natural number 1, 2, 3, …, n1≤N, and N is the number of stator slots.

3. An oil-cooled permanent magnet electric machine according to claim 2, characterized in that, The inner circle of the channel hole is provided with a micro flow channel with a width or inner diameter of 0.5-1 mm.

4. The oil-cooled permanent magnet electric machine according to claim 1 or 2 or 3, characterized in that, The stator-rotor air gap oil cooling channel (5.3.2) is a stator-rotor air gap.

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