High-power-density motor winding direct cooling device and design method

Abstract

The invention provides a high-power-density motor winding direct cooling device and a design method, the device comprises a spiral cooling flow channel, the spiral cooling flow channel is arranged in a stator slot of a motor, and the screw pitch of the spiral cooling flow channel changes in a segmented manner along the axial direction of the motor; the spiral cooling flow channel is in direct contact with a stator winding arranged in a stator slot of the motor; and a cooling medium is introduced into the spiral cooling flow channel. According to the cooling flow channel, the winding temperature is remarkably reduced, and meanwhile the power density, efficiency and operation reliability of the motor are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of motor cooling technology, specifically relating to a direct winding cooling device and design method suitable for high power density motors. Background Technology

[0002] In aerospace servo drive systems, high-power-density motors serve as core actuators, and their dynamic performance and thermal stability directly affect the response speed and reliability of the aircraft servo system. As aircraft electro-actuation systems evolve towards lightweighting and miniaturization, increasing motor power density has become a key technological approach to achieving miniaturized servo mechanism design. However, due to the increased electromagnetic load and loss density, high-power-density motors experience significantly increased copper and iron losses during operation, leading to aggravated temperature rise in the windings and core.

[0003] Excessive temperature rise not only causes irreversible demagnetization of permanent magnets and aging of insulating materials, but also leads to mechanical deformation due to temperature stress, thus affecting the positioning accuracy of the servo system. This thermo-mechanical-electric coupling problem has become a major technical bottleneck restricting further improvements in the power density of aerospace servo motors. Therefore, developing efficient heat dissipation methods is of great significance for improving the power density of aerospace servo systems. Summary of the Invention

[0004] To address the technical problem of severe overheating in high-power-density motors in existing technologies, this invention provides a direct cooling device and method for high-power-density motor windings. This device employs a segmented variable-pitch spiral cooling channel structure within the stator slots of the high-power-density motor. The spiral cooling channel directly contacts the motor stator windings, effectively improving the motor's power density, efficiency, and operational reliability while reducing the winding temperature.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] This invention provides a direct cooling device for high power density motor windings, including a spiral cooling channel disposed in the stator slot of the motor, the pitch of which varies in segments along the motor axis; the spiral cooling channel is in direct contact with the stator winding disposed in the stator slot of the motor; and a cooling medium is introduced into the spiral cooling channel.

[0007] Furthermore, the spiral cooling channels are arranged between several stator windings, or cover the outside of all stator windings.

[0008] Furthermore, the contact area between the spiral cooling channel and the stator winding is not less than 70% of the outer envelope of the spiral cooling channel.

[0009] Furthermore, the inner diameter of the spiral cooling channel ranges from 1.5mm to 3mm, and the wall thickness of the spiral cooling channel ranges from 0.3mm to 0.8mm.

[0010] Furthermore, the spiral cooling channel is fixed in the stator slot by adhesive bonding, making close contact with the stator winding.

[0011] Furthermore, the spiral cooling channel is made of stainless steel or aluminum alloy, and its outer surface is coated with an insulating layer. The cooling medium is insulating oil or fluorinated liquid.

[0012] Furthermore, the cooling medium is circulated using an oil pump, with the flow rate controlled within the range of 0.2-0.4 L / min.

[0013] This invention also provides a design method for a direct cooling device for high power density motor windings, comprising the following steps:

[0014] Determine the number of segments along the motor axis of the spiral cooling channel pitch;

[0015] Calculate the copper loss density of the stator winding and the iron loss density of the stator core for each segment of the motor's axial direction.

[0016] Calculate the total loss density for each segment along the motor axis, where the total loss density is the sum of the stator winding copper loss density and the stator core iron loss density;

[0017] Calculate the target pitch of the spiral cooling channel for each segment along the axial direction of the motor:

[0018]

[0019] Wherein, P(i) is the target pitch of the spiral cooling channel of the i-th segment of the motor axis;

[0020] P0 is the reference pitch;

[0021] β is the adjustment coefficient;

[0022] q total (i) represents the total loss density of the i-th segment of the motor's axial direction;

[0023] q avg This represents the axial average value of the total loss density of the motor.

[0024] Furthermore, the adjustment coefficient β ranges from 0.1 to 0.5, and the formula for calculating the reference pitch P0 is as follows:

[0025]

[0026] Where: L is the axial length of the motor;

[0027] k is the proportionality coefficient;

[0028] N is the number of segments in a defined spiral cooling channel.

[0029] Furthermore, the proportionality coefficient k ranges from 5 to 15, and the number of segments N in the spiral cooling channel is ≥ 3.

[0030] Furthermore, the total loss density q of the i-th segment along the axial direction of the motor total (i) is:

[0031] q total (i)=q cu (i)+q fe (i)

[0032] Where, q cu (i) represents the copper loss density of the stator winding in the i-th segment of the motor's axial direction, q fe (i) represents the stator core iron loss density of the i-th segment of the motor axis;

[0033] The calculation methods for the stator winding copper loss density and stator core iron loss density of the i-th segment of the motor axial direction are as follows:

[0034] q cu (i)=J(i) 2 ·ρ cu

[0035] q fe (i)=k h ·f·B g (i) 1.6 +k e ·f 2 ·B g (i) 2 +k a ·f 1.5 ·B g (i) 1.5

[0036] Where J(i) is the current density of the i-th segment of the motor axis, ρ cu B is the resistivity of the copper wire. g (i) represents the stator core magnetic flux density of the i-th segment along the motor axis, k h k e k a These are the hysteresis loss coefficient, eddy current loss coefficient, and additional loss coefficient, respectively, where f is the motor frequency.

[0037] The beneficial effects of this invention compared to the prior art are as follows:

[0038] This invention provides a direct cooling device for high-power-density motor windings. By correlating the cooling channel pitch with the internal loss distribution of the motor, it achieves a rational allocation of cooling resources and effectively reduces the winding temperature. Through segmented variable pitch distribution, smaller pitches are used in local hot spots to enhance heat exchange. The spiral cooling channel directly contacts the winding, achieving efficient heat dissipation for the high-power-density motor. The use of a metal material with an insulating coating reduces thermal resistance along the heat transfer path, improving the motor's heat dissipation efficiency. This invention mitigates the impact of motor temperature rise on performance and solves the thermal problems of servo motors in aerospace vehicles. Attached Figure Description

[0039] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0040] Figure 1 A three-dimensional structural diagram of a spiral cooling channel within a stator winding, provided for a specific embodiment of the present invention;

[0041] Figure 2 A side view of the spiral cooling channel within the stator winding provided in a specific embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the three-dimensional structure of the spiral cooling channel provided in a specific embodiment of the present invention;

[0043] Figure 4 A front view of a spiral cooling channel provided for a specific embodiment of the present invention.

[0044] The above figures include the following reference numerals:

[0045] 1. Stator core; 2. Stator slot; 3. Stator winding; 4. Spiral cooling channel. Detailed Implementation

[0046] Specific embodiments of the present invention will now be described in detail. In the following description, specific details are set forth for purposes of explanation and not limitation, in order to aid in a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced in other embodiments departing from these specific details.

[0047] It should be noted that, in order to avoid obscuring the invention with unnecessary details, only the device structure and / or processing steps closely related to the solution of the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0048] As one aspect of the present invention, a direct cooling device for high power density motor windings is provided, comprising: a spiral cooling channel disposed in the stator slot of the motor, the spiral cooling channel having a pitch that varies in segments along the motor axial direction; the spiral cooling channel being in direct contact with the stator winding disposed in the stator slot of the motor; and a cooling medium circulating inside the spiral cooling channel.

[0049] This invention discloses a direct cooling device for the stator winding of a high power density motor, including a spiral cooling channel disposed in the stator slot of the high power density motor. The spiral cooling channel is in direct contact with the stator winding of the motor to achieve efficient heat conduction. The pitch of the spiral cooling channel varies in segments along the motor axis. Through this design, the power density, efficiency and operational reliability of the motor are effectively improved while reducing the winding temperature.

[0050] As another aspect of the present invention, a design method for a direct cooling device for high power density motor windings is also provided. This method determines the variation law of variable pitch by establishing a quantitative relationship between pitch and internal loss distribution of the motor, and includes the following steps:

[0051] Determine the number of segments along the motor axis of the spiral cooling channel pitch;

[0052] Calculate the copper loss density of the stator winding and the iron loss density of the stator core for each segment of the motor's axial direction.

[0053] Calculate the total loss density for each segment along the motor axis, where the total loss density is the sum of the stator winding copper loss density and the stator core iron loss density;

[0054] Calculate the target pitch of the spiral cooling channel for each segment along the axial direction of the motor:

[0055]

[0056] Wherein, P(i) is the target pitch of the spiral cooling channel of the i-th segment of the motor axis;

[0057] P0 is the reference pitch;

[0058] β is the adjustment coefficient;

[0059] q total (i) represents the total loss density of the i-th segment of the motor's axial direction;

[0060] q avg This represents the axial average value of the total loss density of the motor.

[0061] This invention provides a design method for a direct cooling device for high power density motor windings, which can guide the design of direct cooling devices for high power density motor windings and ensure cooling effect.

[0062] In one specific embodiment of the present invention, such as Figures 1-4 As shown, a high-power-density motor winding direct cooling device is provided, comprising a stator core 1, stator slots 2, stator windings 3, and a spiral cooling channel 4. The stator core 1 is formed by stacking multiple stator core laminations, and multiple identical stator slots 2 are formed on the stator core 1, the number of slots satisfying the basic principles of motor design. Each stator slot 2 contains a stator winding 3 along the motor axial direction. The spiral cooling channel 4 is fixed within the stator slot 2 and directly contacts the stator windings 3. The spiral cooling channel 4 adopts a variable pitch design, with its pitch P varying segmentally along the motor axial direction, and its variation is determined by the total loss density q at that position. total (i) The decision is made to reduce thermal resistance and improve heat transfer efficiency. Cooling medium is circulated inside the spiral cooling channel 4.

[0063] In one specific embodiment of the present invention, the stator winding 3 is placed in the stator slot 2 and is evenly distributed in the stator slot 2 by a specific winding method.

[0064] In one specific embodiment of the present invention, the spiral cooling channel 4 is arranged between several stator windings 3 or covers the outside of all stator windings 3. The contact area between the spiral cooling channel 4 and the stator windings 3 is not less than 70% of the outer envelope of the spiral cooling channel 4, so as to increase the contact area and ensure the cooling effect.

[0065] In one specific embodiment of the present invention, the inner diameter of the spiral cooling channel 4 is 1.5mm-3mm and the wall thickness is 0.3mm-0.8mm, so as to reduce the space occupied by the cooling channel and increase the heat dissipation effect.

[0066] In one specific embodiment of the present invention, the spiral cooling channel 4 is fixed in close contact with the stator winding 3 in the stator slot 2 by its own integrated insulating skeleton structure or by adhesive bonding, so as to ensure the stability of the structure.

[0067] In one specific embodiment of the present invention, the spiral cooling channel 4 is made of a metal material with high thermal conductivity, preferably stainless steel or aluminum alloy, and an insulating layer is coated on its outer surface to improve the insulation resistance between it and the stator winding 3, so as to avoid short circuit between it and the stator winding 3.

[0068] In one specific embodiment of the present invention, the cooling medium includes, but is not limited to, insulating oil or fluorinated liquid. The spiral cooling channel 4 is circulated with insulating oil or fluorinated liquid to improve the heat dissipation capacity of the stator winding 3; the cooling medium is circulated by an oil pump, with the flow rate controlled at 0.2-0.4 L / min.

[0069] In one specific embodiment of the present invention, the pitch variation law of the spiral cooling channel 4 is optimized based on the total loss density of the motor in the axial position. Specifically, the target pitch P(i) of the i-th segment of the motor axial direction is calculated as follows:

[0070]

[0071] in:

[0072] P(i) is the target pitch of the spiral cooling channel in the i-th segment of the motor axis;

[0073] P0 is the reference pitch;

[0074] β is an adjustment coefficient, ranging from 0.1 to 0.5, used to control the sensitivity of pitch to changes in loss. Setting a larger adjustment coefficient in the higher temperature region can improve heat exchange.

[0075] q total (i) represents the total loss density of the i-th segment of the motor's axial direction, in W / m². 3 ;

[0076] q avg This is the axial average of the total loss density of the motor, in W / m. 3 .

[0077] In this embodiment, the formula for calculating the reference pitch P0 is:

[0078]

[0079] Where: L is the axial length of the motor, in mm;

[0080] k is a proportionality coefficient, ranging from 5 to 15, used to control the number of spiral turns in each fixed pitch flow channel. In motors that generate a lot of heat, setting a larger proportionality coefficient can increase the total number of spiral turns.

[0081] N is the number of segments in a defined spiral cooling channel.

[0082] In this embodiment, the total loss density q of the i-th segment of the motor's axial direction total (i) Consists of copper losses in stator winding 3 and iron losses in stator core 1:

[0083] q total (i)=qcu (i)+q fe (i)

[0084] in:

[0085] Stator winding copper loss density q cu (i)=J(i) 2 ·ρ cu J(i) is the current density of the i-th segment of the motor's axial direction, ρ cu The resistivity of copper wire;

[0086] Stator core iron loss density q fe (i)=k h ·f·B g (i) 1.6 +k e ·f 2 ·B g (i) 2 +k a ·f 1.5 ·B g (i) 1.5 B g (i) represents the stator core magnetic flux density of the i-th segment along the motor axis, k h k e k a These are the hysteresis loss coefficient, eddy current loss coefficient, and additional loss coefficient, respectively, where f is the motor frequency.

[0087] In another aspect of the present invention, a method for direct cooling of high power density motor windings is also provided, comprising the following steps:

[0088] Step 1: Determine the number of segments along the motor axis of the spiral cooling channel. Substitute the selected proportional coefficient k and the determined number of segments N into the reference pitch calculation formula to obtain the reference pitch P0. Obtain the motor axial loss distribution data, calculate the pitch distribution, and manufacture the variable pitch spiral cooling channel 4 accordingly, which is then placed in the stator slot 2 of the high power density motor.

[0089] Based on the loss distribution data obtained during the motor design phase, including the copper loss density q of the stator winding 3. cu (i) and the iron loss density q of the stator core 1 fe (i) Calculate the total loss density q for each segment. total (i) and the axial average value q of the total loss density avg Substitute the calculation results and adjustment coefficient β into the formula for calculating the pitch of the spiral cooling channel:

[0090]

[0091] Calculate the target pitch P(i) for each segment along the axial direction;

[0092] An insulating skeleton with a variable pitch spiral cooling channel 4 was fabricated using 3D printing technology and placed in the stator slot 2 of a high power density motor.

[0093] Step 2: Make the spiral cooling channel 4 directly contact the motor stator winding 3;

[0094] Step 3: Run the motor. Current flows through the stator winding 3 of the motor. Heat is generated due to the resistance of the stator winding 3 itself and the action of the stator core 1 under the alternating magnetic field.

[0095] Step 4: The spiral cooling channel is circulated with cooling medium for forced convection heat exchange, which carries away the heat generated in the stator winding 3 and stator core 1 from the motor through the cooling medium, thereby reducing the temperature rise of the stator winding 3 and achieving the purpose of cooling the motor.

[0096] The working principle of this invention is as follows: When the motor is running, a current is passed through the stator winding 3 to generate a rotating magnetic field that interacts with the rotor magnetic field, driving the motor to run. During operation, the stator winding 3 generates heat due to its own resistance and the alternating magnetic field acting on the stator core 1. The stator winding 3 exchanges heat through direct contact with the cooling channel 4. The heat is carried out of the motor by the cooling medium inside the cooling channel 4. After external circulation cooling, the cooling medium re-enters the motor to achieve circulating heat dissipation, thereby reducing the temperature rise of the stator winding 4 and achieving the purpose of cooling the motor.

[0097] The high power density motor winding direct cooling device provided by this invention can improve the cooling performance of the motor, effectively reduce the impact of motor temperature rise on performance, and solve the thermal problem of servo motors in aerospace vehicles.

[0098] The features described and / or illustrated above with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, and / or in combination with or in lieu of features in other embodiments.

[0099] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, components, or combinations thereof.

[0100] Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0102] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. A direct cooling device for high power density motor windings, characterized in that, It includes a spiral cooling channel, which is disposed in the stator slot of the motor, and its pitch varies in segments along the motor axis; the spiral cooling channel is in direct contact with the stator winding disposed in the stator slot of the motor; and a cooling medium is introduced into the spiral cooling channel.

2. The direct cooling device according to claim 1, characterized in that, The spiral cooling channels are arranged between several stator windings or cover the outside of all stator windings.

3. The direct cooling device according to claim 1, characterized in that, The contact area between the spiral cooling channel and the stator winding is not less than 70% of the outer envelope of the spiral cooling channel.

4. The direct cooling device according to claim 1, characterized in that, The inner diameter of the spiral cooling channel ranges from 1.5mm to 3mm, and the wall thickness of the spiral cooling channel ranges from 0.3mm to 0.8mm.

5. The direct cooling device according to claim 1, characterized in that, The spiral cooling channel is fixed in the stator slot by adhesive in close contact with the stator winding.

6. The direct cooling device according to claim 1, characterized in that, The spiral cooling channel is made of stainless steel or aluminum alloy and its outer surface is coated with an insulating layer. The cooling medium is insulating oil or fluorinated liquid. The cooling medium is driven by an oil pump for circulation, and the flow rate is controlled within the range of 0.2-0.4 L / min.

7. A design method for a direct cooling device for high power density motor windings, characterized in that, Includes the following steps: Determine the number of segments along the motor axis of the spiral cooling channel pitch; Calculate the copper loss density of the stator winding and the iron loss density of the stator core for each segment of the motor's axial direction. Calculate the total loss density for each segment along the motor axis, where the total loss density is the sum of the stator winding copper loss density and the stator core iron loss density; Calculate the target pitch of the spiral cooling channel for each segment along the axial direction of the motor: Wherein, P(i) is the target pitch of the spiral cooling channel of the i-th segment of the motor axis; P0 is the reference pitch; β is the adjustment coefficient; q total (i) represents the total loss density of the i-th segment of the motor's axial direction; q avg This represents the axial average value of the total loss density of the motor.

8. The design method of the direct cooling device according to claim 7, characterized in that, The adjustment coefficient β ranges from 0.1 to 0.5, and the formula for calculating the reference pitch P0 is as follows: Where: L is the axial length of the motor; k is the proportionality coefficient; N is the number of segments in a defined spiral cooling channel.

9. The method for calculating the reference pitch P0 according to claim 8, characterized in that, The proportionality coefficient k ranges from 5 to 15, and the number of segments N in the spiral cooling channel is ≥ 3.

10. The design method of the direct cooling device according to claim 7, characterized in that, The total loss density q of the i-th segment of the motor axial direction total (i) is: q total (i)=q cu (i)+q fe (i) Where, q cu (i) represents the copper loss density of the stator winding in the i-th segment of the motor's axial direction, q fe (i) represents the stator core iron loss density of the i-th segment of the motor axis; The calculation methods for the stator winding copper loss density and stator core iron loss density of the i-th segment of the motor axial direction are as follows: q cu (i)=J(i) 2 ·ρ cu q fe (i)=k h ·f·B g (i) 1.6 +k e ·f 2 ·B g (i) 2 +k a ·f 1.5 ·B g (i) 1.5 Where J(i) is the current density of the i-th segment of the motor axis, ρ cu B is the resistivity of the copper wire. g (i) represents the stator core magnetic flux density of the i-th segment along the motor axis, k h k e k a These are the hysteresis loss coefficient, eddy current loss coefficient, and additional loss coefficient, respectively, where f is the motor frequency.

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