Reluctance motor and internal circulation heat dissipation method

Abstract

The invention discloses a reluctance motor and an internal circulation heat dissipation method, and belongs to the technical field of reluctance motor heat dissipation. Which comprises a shell, a stator iron core and a rotor iron core are arranged in the shell, end plates are arranged on the end faces of the two ends of the rotor iron core respectively, and is characterized in that each end plate comprises a first end plate and a second end plate which are arranged in an asymmetric structure, rotor grooves in the surface of the rotor iron core form a rotor air duct (10), and stator grooves in the surface of the stator iron core form a stator air duct (9); the first end plate and the second end plate are located at the two ends of the rotor air duct (10) respectively, and an air duct opening, located at one end of the second end plate, of the rotor air duct (10) is smaller than an air duct opening, located at one end of the first end plate, of the rotor air duct (10). According to the reluctance motor and the internal circulation heat dissipation method, the asymmetric rotor end plate structure is adopted, internal circulation heat dissipation of the inner cavity of the reluctance motor is achieved, the heat dissipation efficiency of the rotor and the winding end is improved, the manufacturing and modification cost is low, and the defects of an existing heat dissipation mode can be effectively overcome.

Description

Technical Field

[0001] A reluctance motor and an internal circulation heat dissipation method belong to the technical field of heat dissipation of reluctance motors. Background Art

[0002] Reluctance motors (RGMs) include switched reluctance motors and synchronous reluctance motors. They feature no windings, cast aluminum, or permanent magnets on the rotor, and are constructed solely from laminated silicon steel sheets. They deliver pure reluctance torque, offer high reliability, and are suitable for harsh operating conditions. However, as motor power density continues to increase, heat dissipation has become a key constraint on the performance and reliability of RGMs. Traditional motor cooling methods include natural cooling, forced air cooling, and liquid cooling. Heat is transferred from the motor to a heat sink through the stator core and frame. However, dissipating heat from the rotor and stator winding ends within the motor remains a challenge, relying solely on heat transfer within the motor cavity, which is extremely inefficient. Traditional solutions involve installing an internal fan on the motor rotor and adding internal air ducts to the frame to create internal air convection to improve heat dissipation efficiency. However, this approach increases mechanical losses, reducing motor efficiency. Adding air ducts to the frame also increases structural complexity and manufacturing cost.

[0003] With the continuous development of technology, some heat dissipation methods for reluctance motors have also emerged in the existing art. For example, the Chinese invention patent with application number 201911024551.0, application date October 25, 2019, and patent name "A method for internal circulation heat dissipation of a motor and its structure" describes a technical solution in which a skewed pole rotor is used, and the rotor teeth form the function of axial fan blades to promote the flow of air within the motor. However, this method requires opening holes in the motor base, which reduces the motor's protection level and is greatly restricted by the application environment. The Chinese invention patent with application number 202310896362.2, application date July 21, 2023, and patent name "A heat dissipation system and its high-power switched reluctance motor" describes a technical solution in which an air guide shell is added to the base of the switched reluctance motor, and an external fan alternately ventilates the inside and outside of the motor. However, this structure loses some of the external cooling air volume, reduces the heat dissipation capacity of the motor base, and also has the disadvantage of a reduced protection level. The Chinese invention patent with application number 202311125015.6 and application date September 3, 2023, and the patent name "A switched reluctance motor with multi-directional self-circulating ventilation and cooling function" records a technical solution in which complex heat sinks and heat sinks are constructed in the inner cavity of the switched reluctance motor base, which can improve the heat dissipation capacity of the motor stator. However, the structure is complex, the cost is extremely high, and there is no improvement in the heat dissipation of the rotor.

[0004] Therefore, designing a technical solution with simple structure, low cost and conducive to improving the heat dissipation efficiency of the rotor and winding ends has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and provide a reluctance motor and an internal circulation heat dissipation method that realizes internal circulation heat dissipation in the inner cavity of the reluctance motor through an asymmetric rotor end plate structure, which is beneficial to improving the heat dissipation efficiency of the rotor and winding ends, has low manufacturing and modification costs, and can effectively make up for the shortcomings of existing heat dissipation methods.

[0006] The technical solution adopted by the present invention to solve its technical problems is: the reluctance motor includes a shell, a stator core and a rotor core are arranged in the shell, and end plates are respectively arranged at the end faces of both ends of the rotor core, which is characterized in that: the end plate includes a first end plate and a second end plate arranged in an asymmetric structure, the rotor slots on the surface of the rotor core form a rotor air duct, the rotor slots on the surface of the stator core form a stator air duct, and the rotor air duct and the stator air duct constitute a circulating air duct; the first end plate and the second end plate are respectively located at the two ends of the rotor air duct, and the air duct opening of the rotor air duct at one end of the second end plate is smaller than the air duct opening at one end of the first end plate.

[0007] Preferably, the outer diameter of the second end plate is equal to the outer diameter of the rotor core, and an air duct hole is opened around the second end plate. The air duct hole is a through hole axially passing through the second end plate. The air duct hole corresponds to the rotor slot one by one, and the area of ​​the air duct hole is smaller than the area of ​​the rotor slot.

[0008] Preferably, the cross-sectional structure of the first end plate is the same as the cross-sectional structure of the rotor core.

[0009] Preferably, the stator assembly includes a stator core, stator slots arranged on the surface of the stator core form a stator air duct, and the stator air duct and the rotor air duct form a circulation air duct.

[0010] Preferably, the air duct hole is a fan-shaped through hole, the inner diameter of the air duct hole is equal to the inner diameter of the rotor slot, and the radian of the fan-shaped center angle of the air duct hole is equal to the radian of the fan-shaped center angle of the rotor slot.

[0011] Preferably, the first end plate is the axial extension end plate, and the second end plate is the non-axial extension end plate. The axial extension end plate is located at the end surface of the stator core facing the axial extension end of the housing, and the non-axial extension end plate is located at the end surface of the stator core facing away from the axial extension end of the housing.

[0012] An internal circulation heat dissipation method, characterized by comprising the following steps:

[0013] Step 1: Obtain the axial pressure difference ΔP from the second end plate to the first end plate axial ;

[0014] Step 2, obtaining the rotor slot flow resistance;

[0015] Step 3, obtaining the axial air volume from the second end plate to the first end plate;

[0016] Step 4, calculating the rotor heat dissipation power;

[0017] Step 5: Determine the diameter of the rotor air duct at one end of the second end plate when the rotor heat dissipation power is maximum based on the second-order derivative judgment method of the function extreme value;

[0018] Step 6: Determine the internal circulation air duct of the reluctance motor.

[0019] Preferably, in step 4, the calculation formula for the rotor heat dissipation power is:

[0020]

[0021] Where Q is the axial air volume from the second end plate to the first end plate, ρ is the air density, c p is the specific heat capacity of the gas, ΔT is the temperature rise of the gas, ΔP L is the pressure difference at the first end plate, R slot is the rotor slot flow resistance, R L is the outer diameter of the rotor, r is the outer diameter of the rotor air duct at the air duct opening at one end of the second end plate, r s is the radius of the rotor slot bottom, μ is the dynamic viscosity of the fluid, L slot is the axial length of the rotor slot, and ω is the angular velocity of the rotor.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In the reluctance motor and internal circulation heat dissipation method of the present application, an asymmetric rotor end plate structure is adopted, that is, the air duct opening at one end of the rotor air duct is smaller than the air duct opening at the other end, and the centrifugal force difference and fluid inertia effect brought by the asymmetric rotor end plates on both sides of the reluctance motor rotor are utilized to form an axial air pressure difference in the rotor slot, driving the air flow from the high-pressure side to the low-pressure side, generating a driving pressure for air circulation in the motor cavity, and realizing internal circulation heat dissipation in the reluctance motor cavity, which is beneficial to improving the heat dissipation efficiency of the rotor and winding ends, has low manufacturing and modification costs, can effectively make up for the shortcomings of existing heat dissipation methods, is beneficial to solving the heat dissipation problems of the rotor and winding ends, and improves the reliability of the motor. It can be used as a supplement to traditional motor heat dissipation methods to adapt to long-term operation of the motor in overload or high-temperature environments.

[0024] The reluctance motor and internal circulation heat dissipation method disclosed in this application achieve internal circulation heat dissipation in the reluctance motor, increasing the heat dissipation efficiency of the motor rotor by over 50%. This helps solve the heat dissipation issues of the rotor and winding ends, improves motor reliability, and can supplement traditional motor heat dissipation methods to adapt to overload or high-temperature operation. Furthermore, the method is highly versatile, with low manufacturing and modification costs, independent of specific specifications and parameters, and applicable to reluctance motors of different pole numbers and power levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a partial cross-sectional view from the front of the reluctance motor.

[0026] Figure 2 This is a left view of the rotor core assembly and stator core assembly in the reluctance motor.

[0027] Figure 3 Schematic diagram of the end plate at the shaft extension end of the reluctance motor

[0028] Figure 4 Schematic diagram of the non-shaft end plate of the reluctance motor

[0029] Among them: 1, motor shaft 2, end cover 3, stator winding 4, housing 5, shaft end end plate 6, stator core 7, rotor core 8, non-shaft end end plate 9, stator air duct 10, rotor air duct 11, end plate teeth 12, end plate slots 13, air duct holes. DETAILED DESCRIPTION

[0030] Figures 1 to 4 The best embodiment of the present invention is shown below in conjunction with the attached Figures 1 to 4 The present invention is further described.

[0031] like Figure 1 As shown, similar to the prior art, the reluctance motor includes a housing formed by joining a housing 4 and an end cap 2. One end of the housing is the shaft extension end, and the other end is the non-shaft extension end. The motor shaft 1 extends from the center of the shaft extension end. A stator assembly and a rotor assembly are disposed within the housing. The rotor assembly is rotatably positioned at the center of the stator assembly. The motor shaft 1 is coaxially fixed to the axis center of the rotor core 7.

[0032] Combine Figure 2 The stator assembly includes a stator core 6 arranged on the inner wall of the housing 4. A plurality of stator teeth are evenly arranged on the surface of the stator core 6, and a stator winding 3 is provided on the stator teeth. The rotor assembly includes a rotor core 7 arranged at the center of the stator core 6 and a motor shaft 1.

[0033] End plates are provided at both end faces of the rotor core 7: an end plate 5 at the axial extension end of the housing and an end plate 8 at the non-axial extension end of the housing. Figure 3The end plate 5 at the shaft extension end is plate-shaped, and its cross section is the same as that of the rotor core 7 , including a plurality of evenly distributed end plate teeth 11 , with end plate slots 12 formed between two adjacent end plate teeth 11 .

[0034] like Figure 4 As shown, the non-axial extension end plate 8 is annular, and the axial extension end plate 5 and the non-axial extension end plate 8 are both fixed to the motor shaft 1 through their respective center holes. The outer diameter and inner diameter of the axial extension end plate 5 and the non-axial extension end plate 8 are the same.

[0035] A plurality of air duct holes 13 are evenly arranged on the outer ring of the center hole of the end plate 8 at the non-axial extension end. The air duct holes 13 are fan-shaped through holes. The inner diameter of the air duct hole 13 is equal to the diameter at the bottom of the end plate slot 12 (that is, the diameter of the bottom of the rotor slot on the surface of the rotor core 7), and the central angle radian of the fan-shaped air duct hole 13 is the same as the central angle radian of the fan-shaped end plate slot 12 (that is, the central angle radian of the rotor slot on the surface of the rotor core 7).

[0036] The number of air duct holes 13 is the same as the number of end plate slots 12. When the axially extended end plate 5 and the non-axially extended end plate 8 are respectively fixed to the ends of the rotor core 7, the air duct holes 13, their corresponding end plate slots 12, and the rotor slots of the rotor core 7 axially overlap. At this point, a number of axial rotor air ducts 10 are formed within the rotor slots on the surface of the rotor core 7. The air duct holes 13 are the ports of the rotor air ducts 10 located at the non-axially extended end. Simultaneously, stator air ducts 9 are formed between two adjacent stator windings 3 (in the stator slots) in the stator core 6.

[0037] An application to Figure 1 The internal circulation heat dissipation method of the reluctance motor of the structure shown includes the following steps:

[0038] Step 1: Obtain the axial pressure difference ΔP between the non-axial extension end plate 8 and the axial extension end plate 5 axial ;

[0039] When the rotor of the reluctance motor rotates, the air generates a radial pressure gradient in the rotor slot under the action of centrifugal force. By utilizing the centrifugal force difference on both sides of the rotor and the fluid inertia effect, an axial air pressure difference ΔP is formed in the rotor slot. axial , driving the air flow from the high-pressure side to the low-pressure side, generating the driving pressure for the air internal circulation. The pressure difference of the end plate 5 at the shaft extension end is:

[0040]

[0041] Where ρ is the air density, ω is the angular velocity of the rotor, and R L is the outer diameter of the rotor, and r is the outer diameter of the air duct hole 13.

[0042] Since the shaft end plate 5 does not block the rotor slot, it can be approximated to 0. Therefore, the axial pressure difference ΔP from the non-shaft end plate 8 to the shaft end plate 5 is axial =ΔP L .

[0043] Step 2: Obtain the rotor slot flow resistance.

[0044] The shape of the air inlet formed by the non-axial end plate 8 and the rotor slot is approximately rectangular. When the slot width w of the air inlet is much larger than the slot height h, the slot flow resistance is approximately:

[0045]

[0046] Among them, L slot is the axial length of the rotor slot, r s is the radius of the rotor slot bottom, w is the slot width of the air inlet, h is the slot height of the air inlet, r is the outer diameter of the air duct hole 13, and ω is the angular velocity of the rotor.

[0047] Step 3, obtaining the axial air volume from the non-axial extension end plate 8 to the axial extension end plate 5;

[0048] The calculation formula for the axial air volume Q from the non-axial end plate 8 to the axial end plate 5 is:

[0049]

[0050] Where ΔP axial is the axial pressure difference between the non-axial end plate 8 and the axial end plate 5, ΔP L is the pressure difference at the end plate 5 of the shaft extension, R slot is the rotor slot flow resistance obtained in step 2.

[0051] Step 4, calculating the rotor heat dissipation power;

[0052] The calculation formula for the rotor heat dissipation power is:

[0053]

[0054] Where Q is the axial air volume from the non-axial end plate 8 to the axial end plate 5, ρ is the air density, c p is the specific heat capacity of the gas, ΔT is the temperature rise of the gas, ΔP L is the pressure difference at the end plate 5 of the shaft extension, R slot is the rotor slot flow resistance, R L is the outer diameter of the rotor, r is the outer diameter of the air duct hole 13, r s is the radius of the rotor slot bottom, μ is the dynamic viscosity of the fluid, L slot is the axial length of the rotor slot, and ω is the angular velocity of the rotor.

[0055] Step 5: Determine the outer diameter of the air duct hole 13 when the rotor heat dissipation power is maximum according to the second-order derivative judgment method of the function extreme value;

[0056] According to the rotor heat dissipation power formula obtained in step 4, if the function y=F(r) has a second-order derivative at point r0, and F(r0)=0, F"(r0)<0, then the function F(r) obtains a maximum value at r0, so there must be an optimal r value so that the heat dissipation power P in the rotor slot is cool The maximum value of F(r) and the corresponding r0 value, that is, the outer diameter of the air duct hole 13, can be calculated by Matlab calculation software.

[0057] Step 6, determining the internal circulation air duct of the reluctance motor;

[0058] The internal circulation air duct path of the air in the inner cavity of the reluctance motor is: non-axial end end plate 8 → rotor air duct 10 → axial end end plate 5 → front end of stator winding 3 → stator air duct 9 → rear end of stator winding 3 → non-axial end end plate 8.

[0059] The above-mentioned internal circulation heat dissipation method is further explained below based on an example:

[0060] Taking a 37kW 12 / 8-pole switched reluctance motor as an example, the rotor end plate structure and internal heat dissipation method described above are further explained. The initial motor parameters are: rotor core 7 outer diameter 210mm, rotor core 7 inner diameter 90mm, shaft diameter 80mm, rotor pole arc 17°, rotor yoke thickness 32mm, and core length 170mm.

[0061] Step 1: Obtain the axial pressure difference ΔP between the non-axial extension end plate 8 and the axial extension end plate 5 axial ;

[0062] According to the parameters of the 37kW 12 / 8-pole switched reluctance motor, the rotor outer diameter R in the axial pressure difference formula can be determined. L is 105mm, the rotor slot bottom radius r s The rotor angular velocity ω is 157 rad / s at rated operation, and the air density ρ is 1.293 kg / m 3 .

[0063] Step 2, obtaining the rotor slot flow resistance;

[0064] In the rotor slot flow resistance formula, the fluid dynamic viscosity μ is 1.90×10 -5 Pa·s (40°C), rotor slot axial length L slot It is 170mm.

[0065] Step 3: Based on the calculations in Steps 1 and 2, obtain the axial air volume Q from the non-axial extension end plate 8 to the axial extension end plate 5;

[0066] Step 4, calculating the rotor heat dissipation power;

[0067] In the above calculation formula of rotor heat dissipation power, the gas specific heat capacity c p is 1.005 kJ / (kg·K), and ΔT is set to 2°C, then we get:

[0068] F(r)=(105 2 -r 2 )(r 2 -77 2 )

[0069] Using MATLAB software to calculate, we can get the extreme point: F(92.07)=6748529,

[0070] That is, when r≈92 mm, F(r) is the largest, that is, the outer diameter r of the air duct hole 13 is 92 mm.

[0071] After calculation, the theoretical maximum heat dissipation power of the internal cycle is P cool It is 735.2W.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A reluctance motor comprising a housing, a stator core (6) and a rotor core (7) disposed within the housing, and end plates disposed at end surfaces of both ends of the rotor core (7), characterized in that: The end plates include a first end plate and a second end plate arranged in an asymmetric structure; the rotor slots on the surface of the rotor core (7) form a rotor air duct (10); the stator slots on the surface of the stator core (6) form a stator air duct (9); the rotor air duct (10) and the stator air duct (9) constitute a circulating air duct; the first end plate and the second end plate are respectively located at two ends of the rotor air duct (10); and the air duct opening of the rotor air duct (10) at one end of the second end plate is smaller than the air duct opening at one end of the first end plate.

2. The reluctance motor according to claim 1, wherein: The outer diameter of the second end plate is equal to the outer diameter of the rotor core (7), and an air duct hole (13) is opened around the circumference of the second end plate. The air duct hole (13) is a through hole axially penetrating the second end plate. The air duct hole (13) corresponds to the rotor slot one by one, and the area of ​​the air duct hole (13) is smaller than the area of ​​the rotor slot.

3. The reluctance motor according to claim 1 or 2, characterized in that: The cross-sectional structure of the first end plate is the same as that of the rotor core (7).

4. The reluctance motor according to claim 2, wherein: The air duct hole (13) is a fan-shaped through hole, the inner diameter of the air duct hole (13) is equal to the inner diameter of the rotor slot, and the radian of the fan-shaped central angle of the air duct hole (13) is equal to the radian of the fan-shaped central angle of the rotor slot.

5. The reluctance motor according to claim 1, wherein: The first end plate is an axial extension end plate (5), and the second end plate is a non-axial extension end plate (8). The axial extension end plate (5) is located at the end surface of the stator core (6) facing the axial extension end of the housing, and the non-axial extension end plate (8) is located at the end surface of the stator core (6) facing away from the axial extension end of the housing.

6. An internal circulation heat dissipation method applied to a reluctance motor according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Obtain the axial pressure difference ΔP from the second end plate to the first end plate axial ; Step 2, obtaining the rotor slot flow resistance; Step 3, obtaining the axial air volume from the second end plate to the first end plate; Step 4, calculating the rotor heat dissipation power; Step 5, determining the diameter of the rotor air duct (10) located at one end of the second end plate when the rotor heat dissipation power is maximum according to the second-order derivative judgment method of the function extreme value; Step 6: Determine the internal circulation air duct of the reluctance motor.

7. The internal circulation heat dissipation method according to claim 6, characterized in that: In step 4, the calculation formula for the rotor heat dissipation power is: Where Q is the axial air volume from the second end plate to the first end plate, ρ is the air density, c p is the specific heat capacity of the gas, ΔT is the temperature rise of the gas, ΔP L is the pressure difference at the first end plate, R slot is the rotor slot flow resistance, R L is the outer diameter of the rotor, r is the outer diameter of the rotor air duct (10) at the air duct opening at one end of the second end plate, and r s is the radius of the rotor slot bottom, μ is the dynamic viscosity of the fluid, L slot is the axial length of the rotor slot, and ω is the angular velocity of the rotor.

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