Heat dissipation structure of high-power high-speed permanent magnet synchronous motor

Abstract

The invention discloses a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor, in the heat dissipation structure, a stator core is sleeved outside a stator spacer bush, the stator spacer bush is integrally nested in a motor shell, and two ends of an annular cavity formed between the stator spacer bush and the motor shell are respectively subjected to end face sealing through a support frame; the two ends of the stator spacer bush are arranged outside the annular protruding shoulders in the supporting frames on the corresponding sides in a sleeving mode respectively, and therefore an annular closed cavity is formed through the stator spacer bush, the supporting frames and the motor shell. The stator core is sleeved with a stator oil circulation lining, and the stator oil circulation lining and the motor shell are in interference fit to form an oil circulation cooling structure which is used for dissipating heat of the stator core through a cooling medium flowing through an oil circulation flow channel. Stator grooves penetrating through the axial direction of the stator iron core are uniformly formed in the stator iron core in the circumferential direction, windings are embedded in the stator grooves, and runner holes are formed in the windings embedded in the stator grooves in the axial direction of the stator iron core, so that an in-groove cooling structure is formed and used for cooling the windings through cooling media flowing through the runner holes. According to the technical scheme, the heat dissipation problem of an existing high-power and high-speed permanent magnet synchronous motor is solved, and the problem that circulating oil cooling and oil injection cooling are not suitable for the high-power and high-speed permanent magnet synchronous motor is solved.

Description

Technical Field

[0001] The present invention relates to the field of, but is not limited to, aviation motor heat dissipation design technology, and in particular to a heat dissipation structure of a high-power, high-speed permanent magnet synchronous motor. Background Art

[0002] High power density and high torque density are the long-term trends in the development of motors. Permanent magnet synchronous motors have attracted extensive attention in the fields of flywheel energy storage, aerospace, high-speed grinders, compressors, etc. due to their advantages such as high efficiency, high specific power, high power factor, high reliability and easy maintenance. The power limit capacity of a motor is often limited by the temperature rise limit of the motor. For permanent magnet synchronous motors, their performance decreases as the temperature rises. In aerospace, motors are required to have high power and small size and weight, which results in large motor losses and concentrated heat, making the overall heat dissipation design of the motor more difficult.

[0003] At present, air-cooled and liquid-cooled heat dissipation systems are commonly used in aviation permanent magnet synchronous motors. Air-cooled heat dissipation systems are widely used in small-power motors due to their advantages such as low cost, high reliability and easy installation. Compared with air-cooled systems, the heat dissipation efficiency of liquid-cooled heat dissipation systems can reach 50 times that of air-cooled systems, which is suitable for heat dissipation occasions with high heat generation and high heat flux density of generators. At present, liquid-cooled heat dissipation systems mainly include three cooling structures: circulating oil cooling, oil injection cooling and oil immersion cooling; among them, for circulating oil cooling, the heat of the winding needs to be transferred to the circulating oil flow channel through the insulation structure, paint and stator core in the slot. The transfer path is long, the thermal resistance is large, the heat dissipation efficiency is low, and the matching tolerance between the components will affect the thermal resistance of the transfer path; for oil injection cooling, the cooling medium can directly contact the end of the winding to take away the heat, but the cavity is in an oil-gas mixture state, and oil stirring loss is prone to occur between the stator and rotor, generating a lot of heat. For high-power, high-speed permanent magnet synchronous motors, the heat generated is large and the heat is concentrated. The performance of circulating oil cooling is poor and cannot meet the requirements. Oil injection cooling is prone to oil churning losses and is not recommended, making the heat dissipation design of high-power, high-speed permanent magnet synchronous motors more difficult. Summary of the invention

[0004] Purpose of the invention: In order to solve the above-mentioned technical problems, an embodiment of the present invention provides a heat dissipation structure of a high-power, high-speed permanent magnet synchronous motor to solve the heat dissipation problem of existing high-power, high-speed permanent magnet synchronous motors, and solve the problem that circulating oil cooling and oil injection cooling are not applicable to high-power, high-speed permanent magnet synchronous motors.

[0005] Technical solution of the present invention: The embodiment of the present invention provides a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor, the permanent magnet synchronous motor includes a stator core and a winding nested in a stator core slot, the heat dissipation structure includes: a motor housing, a stator spacer, a support frame, and a stator oil circulation bushing;

[0006] Wherein, the motor housing and the stator spacer are both configured as an annular sleeve structure, the stator core is sleeved outside the stator spacer, the stator spacer is integrally nested inside the motor housing, and both ends of the annular cavity formed between the stator spacer and the motor housing are respectively sealed by a support frame, and the two ends of the stator spacer are respectively sleeved outside the annular boss in the corresponding side support frame, thereby forming an annular closed cavity through the stator spacer, the support frame, and the motor housing;

[0007] The stator core is provided with a stator oil circulation bushing on the outside, and the stator oil circulation bushing and the motor housing are formed into an oil circulation channel through interference fit, that is, an oil circulation cooling structure is formed, which is used to dissipate heat from the stator core through the cooling medium flowing through the oil circulation channel;

[0008] The stator core is uniformly provided with stator slots that penetrate the axial direction of the stator core along the circumferential direction, and windings are embedded in the stator slots. Moreover, the windings embedded in the stator slots are provided with flow channel holes along the axial direction of the stator core to form an in-slot cooling structure for dissipating heat from the windings by means of a cooling medium flowing through the flow channel holes.

[0009] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above,

[0010] The oil circulation cooling structure and the in-slot cooling structure adopt a series structure, a liquid inlet is provided at the entrance of the oil circulation channel of the motor housing, and a liquid outlet is provided on the motor housing or one side support frame, so that the cooling medium flows through the oil circulation channel through the liquid inlet and enters one side cavity of the annular sealing cavity. The cooling medium in the side cavity flows into the other side cavity of the annular sealing cavity through the flow channel hole in the winding and then flows out from the liquid outlet.

[0011] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above,

[0012] The oil circulation cooling structure and the tank cooling structure adopt independent structures, and the motor housing is provided with a set of liquid inlet and liquid outlet at both ends of the oil circulation oil channel, which serve as the liquid inlet and liquid outlet of the oil circulation cooling structure;

[0013] The support frame or the motor housing is provided with a set of liquid inlet and liquid outlet at both ends of the annular sealing cavity, which serve as the liquid inlet and liquid outlet of the cooling structure in the tank.

[0014] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above,

[0015] The stator oil circulation bushing adopts: a spiral oil circulation flow channel or a zigzag oil circulation flow channel; or,

[0016] The stator oil circulation bushing is processed with the following method: a plurality of parallel rectangular flow channels are first processed, and adjacent rectangular flow channels are slotted to achieve fluid communication, with adjacent slots being located at 180°.

[0017] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above,

[0018] The winding is formed by combining round wires, and the flow channel holes are provided in the winding in at least one of the following ways:

[0019] Method 1: When embedding the wire in each stator slot, fill a round rod. After the entire stator slot is embedded with wire and the varnish is dipped and dried, the round rod is pulled out to form a flow channel hole in the winding.

[0020] Method 2: When the wire is embedded in each stator slot, a round tube is filled in, and the round tube is made of aluminum or ceramic, and the surface of the aluminum tube is coated with insulating paint;

[0021] The round tube or round rod is arranged in the middle of the stator slot, or at the bottom or top of the stator slot.

[0022] Optionally, the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above further includes: a sealing assembly including a plurality of sealing rings;

[0023] A plurality of axial sealing rings are arranged between the annular boss of the support frame and the stator spacer;

[0024] A single or multiple axial sealing rings are arranged between the support frame and the motor housing.

[0025] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above, the design method of the flow channel holes opened in the winding includes:

[0026] Step 1, setting the fluid velocity v of the cooling medium and the circular flow channel diameter d, and making the calculated total fluid flow meet the design requirements;

[0027] Step 2, calculating the Reynolds number Re, and calculating the pressure drop of the cooling structure in the slot, so that the pressure drop of the cooling structure in the slot meets the design requirements;

[0028] Step 3, based on the set fluid velocity, calculate the convection heat transfer coefficient h in the circular flow channel;

[0029] Step 4, checking the heat generation, including: calculating the heat Φ taken away by the fluid. If Φ≥W, the design of the circular flow channel diameter d is completed. Otherwise, return to step 1 to reset the fluid velocity v of the cooling medium and the circular flow channel diameter d, and then recalculate and check, that is, repeat steps 1 to 4 until the requirements are met.

[0030] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above, step 2 comprises:

[0031] Step 21, calculate the total fluid flow q as:

[0032]

[0033] Step 22, calculate the Reynolds number Re as:

[0034] Step 23, calculate the pressure drop Δp of the cooling structure in the tank as:

[0035]

[0036] in,

[0037] Among them, n is the number of circular flow channels in the cooling structure in the slot, which is a given value, ρ is the cooling medium density, d is the diameter of the circular flow channel, v is the fluid velocity, Re is the Reynolds number, μ is the fluid dynamic viscosity, and f is the friction coefficient.

[0038] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above, in step 3, the convective heat transfer coefficient h in the circular flow channel is calculated as:

[0039]

[0040] Where, Nu = 0.023·Re 0.8 ·Pr n ,

[0041] Where Nu is the Nusselt number, Pr is the Prandtl number, C p is the specific heat capacity of the fluid, k is the thermal conductivity; n is the Prandtl index, and when the fluid is heated, n is 0.4.

[0042] Optionally, in the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor as described above, in step 4, the heat Φ taken away by the fluid is calculated as:

[0043] Φ=(nπdl)h(T w -T f );

[0044] Among them, Φ is the heat taken away by the liquid, W is the heat generated by the winding; l is the length of a single circular flow channel hole, T w The maximum temperature of the winding, T f is the fluid temperature and h is the convective heat transfer coefficient.

[0045] Beneficial effects of the present invention: The heat dissipation structure of a high-power, high-speed permanent magnet synchronous motor provided in an embodiment of the present invention, on the one hand, forms an oil circulation channel between a stator oil circulation bushing mounted on the outside of the stator and the motor housing, that is, forms an oil circulation cooling structure for dissipating the heat of the stator core by the cooling medium flowing through the oil circulation channel; on the other hand, windings are embedded in the stator slots, and flow channel holes are provided in the windings embedded in each stator slot along the axial direction of the stator core, forming an in-slot cooling structure for dissipating the heat of the windings by the cooling medium flowing through each flow channel hole. By adopting the heat dissipation structure combining the oil circulation cooling structure and the in-slot cooling structure in the embodiment of the present invention, the cooling medium is dissipated from the stator core to the stator core. Figure 1 The liquid enters the liquid inlet of the motor housing, and the oil circulation channel adopts a rectangular flow channel. After passing through the oil circulation channel, the heat of the stator core is taken away, and then enters the stator cavity. When the liquid fills the left cavity of the annular sealed cavity, it passes through the circular flow channel of the winding under the action of pressure. The cooling medium is in direct contact with the winding, thereby quickly cooling the winding. The cooling medium then flows out from the liquid outlet on the right side of the annular sealed cavity. The heat dissipation structure provided by the embodiment of the present invention adopts a structure of circulating oil cooling and cooling in the slot, so that the heat of the stator core can be quickly taken away by the circulating oil medium, and the heat of the winding is taken away by the cooling medium in the slot, thereby minimizing the thermal resistance on the heat dissipation path and realizing rapid heat dissipation of high-power permanent magnet synchronous motors; when the cooling channel in the slot is blocked, the circulating oil cooling can be used as a second insurance. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor provided by the embodiment of the present invention can avoid the generation of oil stirring loss, greatly improve the power density of the motor, and make the motor run safely and reliably; when the oil circulation cooling and the in-slot cooling series structure are adopted, on the one hand, the stator can be cooled to enhance the heat exchange, and on the other hand, heat dissipation protection can be provided when a failure occurs in the cooling channel in the slot. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0047] Figure 1 A schematic diagram of the overall structure of a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor provided by an embodiment of the present invention;

[0048] Figure 2 for Figure 1 A schematic diagram of an oil-circulating cooling structure in a heat dissipation structure of a high-power, high-speed permanent magnet synchronous motor provided by the illustrated embodiment;

[0049] Figure 3 for Figure 1 A schematic diagram of a cooling structure in a slot in a heat dissipation structure of a high-power, high-speed permanent magnet synchronous motor provided by the illustrated embodiment;

[0050] Figure 4A schematic diagram of simulation calculation results of the heat dissipation structure of a high-power high-speed permanent magnet synchronous motor provided by an embodiment of the present invention;

[0051] Figure 5 The present invention provides a flowchart of a method for designing flow passage holes provided in a winding in a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0053] As explained in the above background technology, air-cooled and liquid-cooled heat dissipation systems are often used for permanent magnet synchronous motors for aviation. Air-cooled heat dissipation systems are widely used in low-power motors; the three cooling structures of liquid-cooled heat dissipation systems generate large amounts of heat and concentrate the heat for high-power and high-speed permanent magnet synchronous motors. The performance of circulating oil cooling is poor and cannot meet the requirements. Oil-spray cooling is prone to oil churning losses and is not recommended, making the heat dissipation design of high-power and high-speed permanent magnet synchronous motors more difficult.

[0054] In order to solve the above problems, an embodiment of the present invention provides a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor, which is a new type of circular wire slot cooling structure, and can achieve rapid cooling of the high-power high-speed permanent magnet synchronous motor.

[0055] The present invention provides the following specific embodiments which can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0056] Figure 1 The overall structure diagram of a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor provided by an embodiment of the present invention. Figure 1 As shown, the high-power high-speed permanent magnet synchronous motor provided by the embodiment of the present invention includes: a stator core and a winding nested in the stator core slot; the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor includes: a motor housing, a stator spacer, a support frame, and a stator oil circulation bushing.

[0057] like Figure 1 As shown, the motor housing and the stator spacer are both configured as an annular sleeve structure, the stator core is sleeved on the outside of the stator spacer, and the stator spacer is integrally nested in the motor housing. The two ends of the annular cavity formed between the stator spacer and the motor housing are respectively sealed at the end faces by a support frame, and the two ends of the stator spacer are respectively sleeved on the outside of the annular boss in the corresponding side support frame, thereby forming an annular closed cavity through the stator spacer, the support frame, and the motor housing.

[0058] The stator core in the embodiment of the present invention is provided with a stator oil circulation bushing on the outside, and the stator oil circulation bushing and the motor housing are formed into an oil circulation channel through interference fit, that is, an oil circulation cooling structure is formed, which is used to dissipate heat from the stator core through the cooling medium flowing through the oil circulation channel. Figure 2 As shown, Figure 1 The illustrated embodiment is a schematic diagram of an oil circulating cooling structure in a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor.

[0059] The stator core in the embodiment of the present invention is uniformly provided with stator slots that penetrate the axial direction of the stator core along the circumferential direction, and windings are embedded in the stator slots. The windings embedded in each stator slot are provided with flow channel holes along the axial direction of the stator core to form an in-slot cooling structure for dissipating heat from the windings through the cooling medium flowing through each flow channel hole. Figure 3 As shown, Figure 1 The illustrated embodiment provides a schematic diagram of a cooling structure in a slot in a heat dissipation structure of a high-power, high-speed permanent magnet synchronous motor.

[0060] In the heat dissipation structure of the permanent magnet synchronous motor with the above structure, the cooling medium first passes through the oil circulation channel to take away the heat of the stator core; then the cooling medium directly contacts the winding and flows through the circular hole in the middle of the winding, reducing the contact thermal resistance and quickly taking away the heat on the winding. This cooling structure avoids the generation of oil stirring loss, greatly improves the power density of the motor, and makes the motor run safely and reliably. The oil circulation cooling and slot cooling series structure can cool the stator and enhance heat exchange on the one hand, and provide heat dissipation protection when the cooling channel in the slot fails on the other hand.

[0061] In one implementation of the embodiment of the present invention, the oil circulation cooling structure and the in-slot cooling structure adopt a series structure. In the series structure, the motor housing is provided with a liquid inlet as the entrance of the oil circulation flow channel, and the motor housing or one side support frame is provided with a liquid outlet, so that the cooling medium flows through the oil circulation channel through the liquid inlet and enters a cavity on one side of the annular sealing cavity. The cooling medium in the cavity on the side flows into the cavity on the other side of the annular sealing cavity through the flow channel hole in the winding and then flows out from the liquid outlet.

[0062] It should be noted that since the series structure only needs to be provided with one night inlet and one liquid outlet, the inlet and outlet interfaces can be reduced and the connection is facilitated.

[0063] In one implementation of the embodiment of the present invention, the oil circulation cooling structure and the in-slot cooling structure adopt independent structures. In the cooling structure provided by the implementation, the motor housing is provided with a set of liquid inlets and liquid outlets at both ends of the oil circulation oil channel, which serve as the liquid inlet and liquid outlet of the oil circulation cooling structure. In the implementation, the support frame or the motor housing is provided with a set of liquid inlets and liquid outlets at both ends of the annular sealing cavity, which serve as the liquid inlet and liquid outlet of the in-slot cooling structure.

[0064] It should be noted that the implementation adopts two independent cooling structures, which can control the two cooling liquids separately, making it easier to control and adjust.

[0065] In one implementation of the embodiment of the present invention, the stator oil circulation bushing adopts: a spiral oil circulation flow channel or a zigzag oil circulation flow channel. In another optional implementation, the stator oil circulation bushing adopts the following method to process the flow channel: firstly, a plurality of parallel rectangular flow channels are processed, and the adjacent rectangular flow channels are connected by slots to achieve fluid communication, and the positions of adjacent slots are 180°; the above-mentioned flow channel processing method is adopted so that the fluid can completely fill the flow channel and better take away the heat; compared with the spiral oil circulation flow channel or the zigzag oil circulation flow channel, the oil circulation structure is easy to process, and the oil circulation flow channel can be processed separately or the flow channel can be formed by slotting in the casing.

[0066] In an implementation of the embodiment of the present invention, the winding is formed by combining round wires and adopts integer-slot distributed winding, and the flow channel holes are opened in the winding in at least one of the following ways:

[0067] Method 1: When embedding the wire in each stator slot, fill a round rod. After the entire stator slot is embedded with wire and the varnish is dipped and dried, the round rod is pulled out to form a flow channel hole in the winding.

[0068] Method 2: When the wire is embedded in each stator slot, a round tube is filled in. The round tube is made of aluminum or ceramic, and the surface of the aluminum tube is coated with insulating paint. The ceramic round tube has good thermal conductivity, high temperature resistance, and insulation resistance.

[0069] The round tube or round rod is arranged in the middle of the stator slot, or at the bottom or top of the stator slot.

[0070] In an implementation of the embodiment of the present invention, the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor further includes: a sealing assembly, specifically including a plurality of sealing rings.

[0071] In this implementation, a plurality of axial sealing rings are arranged between the annular boss of the support frame and the stator spacer; a single or multiple axial sealing rings are arranged between the support frame and the motor housing to prevent oil leakage.

[0072] In addition, the stator spacer can be made of carbon fiber, peek, epoxy resin and other materials.

[0073] The heat dissipation structure of the high-power, high-speed permanent magnet synchronous motor provided in the embodiment of the present invention, on the one hand, forms an oil circulation channel between the stator oil circulation bushing mounted on the outside of the stator and the motor housing, that is, forms an oil circulation cooling structure for dissipating the heat of the stator core through the cooling medium flowing through the oil circulation channel; on the other hand, windings are embedded in the stator slots, and flow channel holes are opened in the windings embedded in each stator slot along the axial direction of the stator core, forming an in-slot cooling structure for dissipating the heat of the windings through the cooling medium flowing through each flow channel hole. By adopting the heat dissipation structure combining the oil circulation cooling structure and the in-slot cooling structure in the embodiment of the present invention, the cooling medium is dissipated from the stator core to the stator core. Figure 1 The liquid enters the liquid inlet of the motor housing, and the oil circulation channel adopts a rectangular flow channel. After passing through the oil circulation channel, the heat of the stator core is taken away, and then enters the stator cavity. When the liquid fills the left cavity of the annular sealed cavity, it passes through the circular flow channel of the winding under the action of pressure. The cooling medium is in direct contact with the winding, thereby quickly cooling the winding. The cooling medium then flows out from the liquid outlet on the right side of the annular sealed cavity. The heat dissipation structure provided by the embodiment of the present invention adopts a structure of circulating oil cooling and cooling in the slot, so that the heat of the stator core can be quickly taken away by the circulating oil medium, and the heat of the winding is taken away by the cooling medium in the slot, thereby minimizing the thermal resistance on the heat dissipation path and realizing rapid heat dissipation of high-power permanent magnet synchronous motors; when the cooling channel in the slot is blocked, the circulating oil cooling can be used as a second insurance. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor provided by the embodiment of the present invention can avoid the generation of oil stirring loss, greatly improve the power density of the motor, and make the motor run safely and reliably; when the oil circulation cooling and the in-slot cooling series structure are adopted, on the one hand, the stator can be cooled to enhance the heat exchange, and on the other hand, heat dissipation protection can be provided when a failure occurs in the cooling channel in the slot.

[0074] In order to compare and illustrate the cooling effect of the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor provided by the embodiment of the present invention, based on the power of the 200kW level permanent magnet synchronous motor, heat source excitation is applied to the winding and the core in the stator assembly, and the cooling medium is 4050 oil. Figure 4As shown, it is a schematic diagram of the simulation calculation results of the heat dissipation structure of the high-power high-speed permanent magnet synchronous motor provided by the embodiment of the present invention. When the conventional oil-circulating cooling structure is adopted, the inlet flow rate is 20L / min. Since the heat of the winding needs to be conducted to the oil-circulating pipeline through the paint, slot insulation, stator core, etc., the heat transfer path is long, the thermal resistance is large, the winding temperature is high, which is 249°C, and the stator cooling effect is good, which is 128°C; when the slot cooling structure provided by the present invention is used alone, the inlet flow rate is 20L / min, and the stator heat needs to be transferred to the winding before it can be taken away, so its heat dissipation effect is limited under a certain heat dissipation area, the winding temperature is 177°C, and the stator temperature is 149°C. When the oil-circulating cooling structure and the slot cooling structure provided by the embodiment of the present invention are used in combination, at a flow rate of 10L / min, the heat of the stator core is quickly taken away by the oil-circulating flow channel, and the heat of the winding is taken away by the slot cooling flow channel, which increases the heat dissipation area, so that the heat is taken away under the minimum transfer path, greatly improving the heat dissipation performance, the highest winding temperature is 148°C, and the stator temperature is 93°C.

[0075] In the embodiment of the present invention, the diameter of the round rod is designed by comprehensively considering the heat exchange performance required to be achieved by the cooling structure in the slot, the flow rate and resistance of the cooling medium.

[0076] like Figure 5 FIG. 1 is a flow chart of a design method for a flow channel hole opened in a winding in a heat dissipation structure of a high-power high-speed permanent magnet synchronous motor provided by an embodiment of the present invention. The design method comprises the following steps:

[0077] Step 1, setting the fluid velocity v of the cooling medium and the circular flow channel diameter d, and making the calculated total fluid flow q meet the design requirements;

[0078] In step 1, the total fluid flow rate q is required not to exceed 40 L / min. If the total flow rate does not meet the requirement, the calculation is repeated until the total flow rate meets the requirement.

[0079] Step 2, calculating the Reynolds number Re, and calculating the pressure drop of the cooling structure in the slot, so that the pressure drop of the cooling structure in the slot meets the design requirements;

[0080] In step 2, for the series structure of oil circulation cooling structure + in-tank cooling structure, the total pressure drop of the cooling medium inlet and outlet is required to be no more than 0.6 MPa, and the pressure drop of the in-tank cooling structure is recommended to be no more than 0.2 MPa; if the fluid pressure drop exceeds 0.2 MPa, return to redesign the fluid velocity and diameter d and solve until the pressure drop does not exceed 0.2 MPa.

[0081] Based on the above design requirements, step 2 includes the following implementation steps:

[0082] Step 21, calculate the total fluid flow q as:

[0083]

[0084] Step 22, calculate the Reynolds number Re as:

[0085] Step 23, calculate the pressure drop Δp of the cooling structure in the tank as:

[0086]

[0087] in,

[0088] Among them, n is the number of circular flow channels in the cooling structure in the slot, which is a given value, ρ is the cooling medium density, d is the diameter of the circular flow channel, v is the fluid velocity, Re is the Reynolds number, μ is the fluid dynamic viscosity, and f is the friction coefficient.

[0089] Step 3, based on the set fluid velocity, calculate the convection heat transfer coefficient h in the circular flow channel;

[0090] The convective heat transfer coefficient h in the circular flow channel is calculated in step 3 as:

[0091]

[0092] Where, Nu = 0.023·Re 0.8 ·Pr n ,

[0093] Where Nu is the Nusselt number, Pr is the Prandtl number, and C p is the specific heat capacity of the fluid, k is the thermal conductivity; n is the Prandtl index, and when the fluid is heated, n is 0.4.

[0094] Step 4, checking the heat generation, including: calculating the heat Φ taken away by the fluid. If Φ≥W, the design of the circular flow channel diameter d is completed. Otherwise, return to step 1 to reset the fluid velocity v of the cooling medium and the circular flow channel diameter d, and then recalculate and check, that is, repeat steps 1 to 4 until the requirements are met.

[0095] In step 4, the heat taken away by the fluid Φ is calculated as:

[0096] Φ=(nπdl)h(T w -T f );

[0097] Where: Φ is the heat taken away by the liquid, W is the heat generated by the winding; l is the length of a single circular flow channel hole, T w is the maximum temperature that the winding can withstand (given value), T f is the fluid temperature and h is the convective heat transfer coefficient.

[0098] The heat dissipation structure formed by the above design in the embodiment of the present invention enables the cooling medium to be in direct contact with the winding, thereby improving the heat dissipation performance and being suitable for solving the problem of high-power heating of high-speed permanent magnet synchronous motors.

[0099] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A heat dissipation structure of a high-power high-speed permanent magnet synchronous motor, characterized in that: The permanent magnet synchronous motor comprises a stator core and a winding nested in a slot of the stator core, and the heat dissipation structure comprises: a motor housing, a stator spacer, a support frame, and a stator oil circulation bushing; Wherein, the motor housing and the stator spacer are both configured as an annular sleeve structure, the stator core is sleeved outside the stator spacer, the stator spacer is integrally nested inside the motor housing, and both ends of the annular cavity formed between the stator spacer and the motor housing are respectively sealed by a support frame, and the two ends of the stator spacer are respectively sleeved outside the annular boss in the corresponding side support frame, thereby forming an annular closed cavity through the stator spacer, the support frame, and the motor housing; The stator core is provided with a stator oil circulation bushing on the outside, and the stator oil circulation bushing and the motor housing are formed into an oil circulation channel through interference fit, that is, an oil circulation cooling structure is formed, which is used to dissipate heat from the stator core through the cooling medium flowing through the oil circulation channel; The stator core is uniformly provided with stator slots that penetrate the axial direction of the stator core along the circumferential direction, and windings are embedded in the stator slots. Moreover, the windings embedded in the stator slots are provided with flow channel holes along the axial direction of the stator core to form an in-slot cooling structure for dissipating heat from the windings by means of a cooling medium flowing through the flow channel holes.

2. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 1 is characterized in that: The oil circulation cooling structure and the in-slot cooling structure adopt a series structure, a liquid inlet is provided at the entrance of the oil circulation channel of the motor housing, and a liquid outlet is provided on the motor housing or one side support frame, so that the cooling medium flows through the oil circulation channel through the liquid inlet and enters one side cavity of the annular sealing cavity. The cooling medium in the side cavity flows into the other side cavity of the annular sealing cavity through the flow channel hole in the winding and then flows out from the liquid outlet.

3. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 1 is characterized in that: The oil circulation cooling structure and the tank cooling structure adopt independent structures, and the motor housing is provided with a set of liquid inlet and liquid outlet at both ends of the oil circulation oil channel, which serve as the liquid inlet and liquid outlet of the oil circulation cooling structure; The support frame or the motor housing is provided with a set of liquid inlet and liquid outlet at both ends of the annular sealing cavity, which serve as the liquid inlet and liquid outlet of the cooling structure in the tank.

4. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 1 is characterized in that: The stator oil circulation bushing adopts: a spiral oil circulation flow channel or a zigzag oil circulation flow channel; or, The stator oil circulation bushing is processed with the following method: a plurality of parallel rectangular flow channels are first processed, and adjacent rectangular flow channels are slotted to achieve fluid communication, with adjacent slots being located at 180°.

5. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 1 is characterized in that: The winding is formed by combining round wires, and the flow channel holes are provided in the winding in at least one of the following ways: Method 1: When embedding the wire in each stator slot, fill a round rod. After the entire stator slot is embedded with wire and the varnish is dipped and dried, the round rod is pulled out to form a flow channel hole in the winding. Method 2: When the wire is embedded in each stator slot, a round tube is filled in, and the round tube is made of aluminum or ceramic, and the surface of the aluminum tube is coated with insulating paint; The round tube or round rod is arranged in the middle of the stator slot, or at the bottom or top of the stator slot.

6. The heat dissipation structure of a high-power high-speed permanent magnet synchronous motor according to any one of claims 1 to 5, characterized in that: Also includes: A sealing assembly, including a plurality of sealing rings; A plurality of axial sealing rings are arranged between the annular boss of the support frame and the stator spacer; A single or multiple axial sealing rings are arranged between the support frame and the motor housing.

7. The heat dissipation structure of a high-power high-speed permanent magnet synchronous motor according to any one of claims 1 to 5, characterized in that: The design method of the flow channel hole opened in the winding includes: Step 1, setting the fluid velocity v of the cooling medium and the circular flow channel diameter d, and making the calculated total fluid flow meet the design requirements; Step 2, calculating the Reynolds number Re, and calculating the pressure drop of the cooling structure in the slot, so that the pressure drop of the cooling structure in the slot meets the design requirements; Step 3, based on the set fluid velocity, calculate the convection heat transfer coefficient h in the circular flow channel; Step 4, checking the heat generation, including: calculating the heat Φ taken away by the fluid. If Φ≥W, the design of the circular flow channel diameter d is completed. Otherwise, return to step 1 to reset the fluid velocity v of the cooling medium and the circular flow channel diameter d, and then recalculate and check, that is, repeat steps 1 to 4 until the requirements are met.

8. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 7, characterized in that: The step 2 comprises: Step 21, calculate the total fluid flow q as: Step 22, calculate the Reynolds number Re as: Step 23, calculate the pressure drop Δp of the cooling structure in the tank as: in, Among them, n is the number of circular flow channels in the cooling structure in the slot, which is a given value, ρ is the cooling medium density, d is the diameter of the circular flow channel, v is the fluid velocity, Re is the Reynolds number, μ is the fluid dynamic viscosity, and f is the friction coefficient.

9. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 8, characterized in that: In step 3, the convective heat transfer coefficient h in the circular flow channel is calculated as: Where, Nu = 0.023·Re 0.8 ·Pr n , Where Nu is the Nusselt number, Pr is the Prandtl number, C p is the specific heat capacity of the fluid, k is the thermal conductivity; n is the Prandtl index, and when the fluid is heated, n is 0.

4.

10. The heat dissipation structure of the high-power high-speed permanent magnet synchronous motor according to claim 9, characterized in that: In step 4, the heat taken away by the fluid Φ is calculated as: Φ=(nπdl)h(T w -T f ); Among them, Φ is the heat taken away by the liquid, W is the heat generated by the winding; l is the length of a single circular flow channel hole, T w The maximum temperature of the winding, T f is the fluid temperature and h is the convective heat transfer coefficient.

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