A low-loss superconducting motor and its design method

Abstract

The present invention discloses a low-loss superconducting motor and its design method, belonging to the technical field of superconducting motors. A low-loss superconducting motor includes a vacuum chamber, in which a stator assembly and a rotor assembly are arranged, and a protective cover is arranged between the stator assembly and the rotor assembly; one of the stator assembly and the rotor assembly is provided with a normal conductor coil, and the other is provided with a superconductor coil. A direct current is applied to the superconductor coil, and an alternating current is applied to the normal conductor coil. At the same time, a design method based on the above superconducting motor is disclosed. By adopting the above low-loss superconducting motor and its design method, the air gap between the stator assembly and the rotor assembly is small, it is easy to achieve a high magnetic field, and the Joule loss of the normal conductor coil is reduced. Air or water cooling pipes can be omitted, and temperature control is easy.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting motors, and in particular to a low-loss superconducting motor and its design method. Background Art

[0002] The winding of a superconducting motor is a motor wound with practical superconducting wires, which has the advantages of high power density and high efficiency, and is a motor with great development potential. Superconducting motors are divided into fully superconducting motors and semi-superconducting motors according to their structures. In a fully superconducting motor, both the stator and the rotor of the motor are superconductors, and both the stator and the rotor are installed in a cryogenic thermostat (vacuum chamber). The air gap between the stator and the rotor is small, and it is easy to achieve a high magnetic field. However, the superconducting coils carrying alternating current have large losses, and it is difficult for the rotor to rotate at high speed in the cryogenic thermostat, and it is difficult to cool. A complex mechanical or electrical system is required to ensure the safe operation of the motor. In a semi-superconducting motor, one of the stator and the rotor is a superconductor and the other is a normal conductor. One of the stator and the rotor is installed inside the cryogenic thermostat, and the other is installed outside the cryogenic thermostat. There is a cryogenic thermostat wall between the stator and the rotor, so the air gap between the stator and the rotor is large, and it is difficult to achieve a high magnetic field. The Joule loss caused by the alternating magnetic field still exists. Summary of the Invention

[0003] The object of the present invention is to provide a low-loss superconducting motor and its design method to solve the above technical problems.

[0004] To achieve the above object, the present invention provides a low-loss superconducting motor, including a vacuum chamber, a stator assembly and a rotor assembly are arranged in the vacuum chamber, and a protective cover is arranged between the stator assembly and the rotor assembly; one of the stator assembly and the rotor assembly is provided with a normal conductor coil, and the other is provided with a superconducting coil, and a direct current is applied to the superconducting coil, and an alternating current is applied to the normal conductor coil.

[0005] Preferably, the rotor assembly includes a rotor support frame and a plurality of superconducting coils arranged on the rotor support frame, and the stator assembly includes a stator support frame and a normal conductor coil arranged on the stator support frame.

[0006] Preferably, a plurality of superconducting coils are circumferentially distributed inside the stator support frame, both ends of the stator support frame are fixedly connected to both ends of the vacuum chamber, a plurality of normal conductor coils are circumferentially distributed outside the rotor support frame, both ends of the stator support frame are fixedly connected to both ends of the vacuum chamber, both ends of the rotor support frame are rotatably connected to both ends of the vacuum chamber through bearings, and the superconducting coils and the normal conductor coils are located at the same axial position.

[0007] Preferably, the protective cover is sleeved on the circumferential side of the rotor support frame, and a radiation heat shield is arranged between the stator support frame and the rotor support frame.

[0008] Preferably, the rotor assembly includes a rotor support frame and a plurality of normal conductor coils disposed on the rotor support frame, and the stator assembly includes a stator support frame and a superconducting coil disposed on the stator support frame.

[0009] Preferably, the top of the stator support frame is a planar structure, and a plurality of superconducting coils are arranged in an array on the planar structure, and the vertical polarities of adjacent superconducting coils are different.

[0010] Preferably, the planar structure is covered with multiple layers of heat insulation films, a protective cover is arranged above the superconducting coils arranged in an array, the protective cover is made of a non-metallic material, and a radiation heat shield is arranged on the protective cover.

[0011] Preferably, the rotor support frame is a frame structure, and at least one group of normal conductor coils is arranged in the frame structure, and each group of normal conductor coils includes at least two normal conductor coils.

[0012] A design method for the above-mentioned low-loss superconducting motor is as follows:

[0013] Step S1: Calculate the stator magnetic field according to the required acceleration in actual use;

[0014] Step S2: Calculate the current of the superconducting coil according to the stator magnetic field;

[0015] Step S3: Calculate the critical current and the temperature of the superconductor according to the current of the superconducting coil;

[0016] Step S4: Determine the cooling system according to the temperature of the superconductor.

[0017] Preferably, step S4 is specifically:

[0018] Step S41: Calculate the heat transfer amount, which includes radiative heat transfer amount, conductive heat transfer amount and wire heat transfer amount;

[0019] Step S42: Calculate the heat required for cooling according to the balance relationship of each heat transfer amount;

[0020] Step S43: Determine the refrigeration system according to the heat required for cooling.

[0021] Therefore, the present invention adopts the above-mentioned low-loss superconducting motor and its design method, and the beneficial effects are as follows:

[0022] (1) Both the stator assembly and the rotor assembly are arranged in a vacuum chamber, a protective cover is arranged between the stator assembly and the rotor assembly, one of the stator assembly and the rotor assembly is provided with a normal conductor coil, the other is provided with a superconducting coil, a direct current is applied to the superconducting coil, an alternating current is applied to the normal conductor coil, the air gap between the stator assembly and the rotor assembly is small, it is easy to achieve a high magnetic field, and the Joule loss of the normal conductor coil is reduced.

[0023] (2) The air or water-cooling pipes can be omitted, and temperature control is easy.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0025] Figure 1 Sectional view of Embodiment 1 of a low-loss superconducting motor according to the present invention;

[0026] Figure 2 Side view of Embodiment 1 of a low-loss superconducting motor according to the present invention;

[0027] Figure 3 Perspective view of Embodiment 1 of a low-loss superconducting motor according to the present invention;

[0028] Figure 4 Sectional view of Embodiment 2 of a low-loss superconducting motor according to the present invention;

[0029] Figure 5 Perspective view of Embodiment 2 of a low-loss superconducting motor according to the present invention;

[0030] Figure 6 Distribution diagram of normal conductor coils in Embodiment 2 of a low-loss superconducting motor according to the present invention;

[0031] Figure 7 Schematic diagram of the structure of superconducting coils in Embodiment 2 of a low-loss superconducting motor according to the present invention;

[0032] Figure 8 Curve diagram of the relationship between the acceleration of the workbench and the stator magnetic field;

[0033] Figure 9 Curve diagram of the relationship between the current in the superconducting coil and the stator magnetic field;

[0034] Figure 10 Curve diagram of the relationship between the temperature of the superconducting coil and the current in the superconducting coil;

[0035] Figure 11 Design range diagram of the temperature of the superconducting coil;

[0036] Figure 12 Curve diagram of the relationship between the acceleration of the workbench and the temperature of the superconducting coil;

[0037] Figure 13 Thermal analysis model diagram in the vacuum chamber;

[0038] Figure 14 Analysis model diagram of normal conductor coils in Embodiment 2;

[0039] Figure 15A graph showing the relationship between the heat required for cooling and the temperature of the superconducting coil.

[0040] Reference numerals

[0041] 1. Vacuum chamber; 2. Rotor support frame; 3. Stator support frame; 4. Normal conductor coil; 5. Superconducting coil; 6. Protective cover; 7. Radiation heat shield cover. Detailed implementation manners

[0042] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0043] The following will describe the implementation manners of the present invention in detail with reference to the drawings.

[0044] Embodiment 1

[0045] As Figures 1-3 shown, a low-loss superconducting motor includes a vacuum chamber 1. Inside the vacuum chamber 1, a stator assembly and a rotor assembly are provided, and a protective cover 6 is provided between the stator assembly and the rotor assembly. In this embodiment, the rotor assembly includes a rotor support frame 2 and a plurality of superconducting coils 5 provided on the rotor support frame 2, and the stator assembly includes a stator support frame 3 and a normal conductor coil 4 provided on the stator support frame 3.

[0046] Both the rotor support frame 2 and the stator support frame 3 are hollow shaft structures. A plurality of superconducting coils 5 are circumferentially distributed inside the stator support frame 3. Both ends of the stator support frame 3 are fixedly connected to both ends of the vacuum chamber 1. A plurality of normal conductor coils 4 are circumferentially distributed outside the rotor support frame 2. Both ends of the rotor support frame 2 are rotatably connected to both ends of the vacuum chamber 1 through bearings. The protective cover 6 is sleeved on the circumferential side of the rotor support frame 2. Compared with the prior art, the air gap between the superconducting coil 5 and the normal conductor coil 4 is greatly reduced, and it is easy to achieve a high magnetic field. At the same time, an alternating current is applied to the normal conductor coil 4, and a direct current is applied to the superconducting coil 5, and the amplitude of the alternating current can be controlled, thereby reducing the Joule loss in the normal conductor coil 4.

[0047] A radiation heat shield 7 is provided between the stator support frame 3 and the rotor support frame 2. The normal conductor coil 4 is cooled by a radiation cooling method, which can eliminate the air or water cooling pipes. The temperature of the normal conductor coil 4 is controlled by controlling the emissivity of the radiation heat shield 7.

[0048] Embodiment 2

[0049] The difference between this embodiment and Embodiment 1 is that the installation positions of the normal conductor coil 4 and the superconducting coil 5 are different, and this embodiment is a planar motor. As Figures 4-5 shown, in this embodiment, the rotor assembly includes a rotor support frame 2 and a plurality of normal conductor coils 4 arranged on the rotor support frame 2, and the stator assembly includes a stator support frame 3 and a superconducting coil 5 arranged on the stator support frame 3.

[0050] As Figure 6 shown, in this embodiment, the rotor support frame 2 is a rectangular frame structure, and the frame structure can also be circular or triangular. The shape of the frame structure can be adjusted according to the actual situation, or it can be an irregular shape. In this embodiment, three normal conductor coils 4 form a set of three-phase normal conductor coils 4. The normal conductor coils 4 are in a racetrack shape. Four sets of three-phase normal conductor coils 4 are placed in the rectangular frame structure, and the normal conductor coils 4 in adjacent three-phase normal conductor coils 4 are in the same plane and perpendicular to each other. An alternating current with a phase difference of 120 degrees is applied to each set of three-phase normal conductor coils 4.

[0051] The number of normal conductor coils 4 in each set of normal conductor coils 4 can also be adjusted according to the actual situation, such as two-phase or four-phase, etc. An alternating current with a phase difference of 90 degrees is applied to the two-phase normal conductor coils 4 and the four-phase normal conductor coils 4.

[0052] The top of the stator support frame 3 is a planar structure, and a plurality of superconducting coils 5 are arranged in an array on the planar structure. As Figure 7 shown, the superconducting coil 5 is a cylindrical coil with a height of H s . The vertical polarities of adjacent superconducting coils 5 are different, that is, the N pole and the S pole are arranged alternately. In this embodiment, 36 N poles and 25 S poles are provided.

[0053] The planar structure is covered with multiple layers of heat insulation films to suppress the radiation heat from the inner wall of the vacuum chamber 1, so as to maintain a low surface emissivity. And the stator support frame 3 is made of G10 material. The G10 material has the advantages of low thermal conductivity and relatively high rigidity. The material of the stator support frame 3 can also be adjusted according to the actual performance. A protective cover 6 is provided above the superconducting coils 5 arranged in an array. The protective cover 6 is made of a non-metallic material to suppress the eddy current loss caused by the rotor magnetic field. The surface emissivity must be set to a large value to cool the normal conductor coil 4. A radiation heat shield 7 is provided on the protective cover 6.

[0054] The air gap length of the traditional semi-superconducting motor is 12 mm, while the air gap length of this embodiment is 2 mm.

[0055] A design method for a low-loss superconducting motor is as follows:

[0056] Step S1: Calculate the stator magnetic field according to the required acceleration.

[0057] The superconducting coils are periodically arranged at a spacing of 2τ, and the magnetic field generated by the superconducting coil array is a fundamental wave with an amplitude of B s and a period of 2τ. Then, a current with an amplitude of I m and a phase angle of φ flows through a set of three-phase coils on the rotor support frame, and the electromagnetic force (F x , F z ) is as follows:

[0058] F x =(3 / 2)KI m sin(φ)

[0059] F z =-(3 / 2)KI m cos(φ) (1)

[0060] Among them, the formula for the force constant K is as follows:

[0061]

[0062] α = πb m / 2τ, L m , b m , N m and are the length, width, number of turns, and filling factor of the normal conductor coils on the rotor support frame, respectively;

[0063] The force generated by the motor is proportional to the stator magnetic field B s of the superconducting coils and the current I m of the normal conductor coils;

[0064] According to the number and arrangement of the three-phase coils on the rotor assembly, the relationship between the workbench acceleration and the force generated by the motor is as follows;

[0065] F x =MA x / 2 F z =Mg / 4 (3)

[0066] Among them, A x is the x-direction acceleration of the workbench, g is the acceleration due to gravity, and M is the mass;

[0067] According to the workbench acceleration A x Determine the stator magnetic field B s And the current I of the normal conductor coil m .

[0068] The planar motors widely used at present generally use a Halbach array of permanent magnets to replace superconducting magnets, and the stator magnetic field B s = 0.6T. Assume I m = 25A (≡I0), N m = 300, then the workbench acceleration Ax = 8G. This is equivalent to the acceleration of the wafer workbench in a modern exposure system.

[0069] As Figure 8 shown, for the current I of the normal conductor coil m = 0.5I0, 0.7I0, 0.8I0, calculate the stator magnetic field required to achieve the workbench acceleration (16G to 32G) according to formulas (1) to (3).

[0070] Compared with traditional motors, the air gap length of the stator assembly and the rotor assembly proposed in this embodiment is smaller, so it is very easy to increase the stator magnetic field B s .

[0071] Step S2: Calculate the current of the superconducting coil according to the stator magnetic field.

[0072] The calculation formula for the stator magnetic field (B x , B z ) is as follows:

[0073]

[0074] The function to be integrated is as follows:

[0075] f x (R, Z, θ) = Aξ + xξ 2 ln(A + K);

[0076]

[0077] Among them,

[0078] C = Z - z J s = N s I s / (b s H s ) η = sinθ ζ = cosθ

[0079] K = R - xζ R1 = D s / 2 - b s R2 = D s / 2 Z2 = Hs / 2 Z1 = -H s / 2

[0080] Wherein, the current in the superconducting coil is I s , μ0 is the magnetic permeability of vacuum, N s is the number of turns, D s is the outer diameter, b s is the width, H s is the height. Compared with the traditional motor, the air gap length between the stator assembly and the rotor assembly proposed in this embodiment is smaller. As Figure 9 shown, from the relationship curve of the current in the superconducting coil and the stator magnetic field, it can be seen that the stator magnetic field proposed in this embodiment can be generated with a smaller superconducting current. Step S3: Calculate the critical current and the temperature of the superconductor according to the current in the superconducting coil.

[0081] The critical current is the maximum value of the current in the superconducting coil. It is a function of the temperature T, the magnitude |B| and the direction φ of the magnetic field around the superconducting coil. In this embodiment, the interpolation function obtained from the existing data is used for calculation, and the interpolation function is:[[]] In order to suppress the AC loss, it is assumed that the critical current I c is much larger than the current I s in the stator coil, then it is expressed as I c = K s I s , K s is the safety factor, and K s is taken as 2 in this embodiment.

[0082] The calculation formula for the temperature of the superconductor is as follows:[[]]

[0083]

[0084] Wherein, T s is the temperature of the superconductor, and V s is the area of the superconducting coil.

[0085] The relationship between the temperature of the superconducting coil and the current in the superconducting coil is as Figure 10 shown. The cooling capacity of the cryocooler will decrease as the temperature decreases, as Figure 11 shown. Therefore, the temperature of the superconducting coil is set between 20K and 45K. If a single-stage refrigerator with a larger cooling capacity can be used within this temperature range, this will increase the advantage of the superconducting magnet over the permanent magnet.

[0086] As Figure 12 shown, it shows the relationship between the workbench acceleration and the temperature of the superconducting coil, indicating that when I m > 0.5I0, the superconducting motor proposed by the present invention can obtain a larger workbench acceleration than the traditional motor. When Im When it is 0.7I0 or higher, the difference between the two is particularly obvious.

[0087] This embodiment uses a single-stage GM refrigerator to cool the motor.

[0088] Step S4: Determine the cooling system according to the superconductor temperature.

[0089] The internal thermal analysis model of the motor in this embodiment is as Figure 13 shown, and it is composed of N planes inside. In the figure, N = 12.

[0090] Step S41: Calculate the heat transfer amount, which includes radiative heat transfer amount, conductive heat transfer amount, and wire heat transfer amount.

[0091] The radiative heat transfer amount q of each plane = [q1, q2,... q N T The calculation formula is as follows:

[0092] q = RP -1 S

[0093]

[0094] Among them, ε i and T j are the emissivity and temperature of the plane j respectively, σ is the Boltzmann constant, and F ij is the shape factor from plane i to plane j. T 10 = T 11 = T 12 = T H (room temperature).

[0095] The conductive heat transfer amounts of the legs and the base of the stator support frame are Q1 and Q3, and the conductive heat transfer amounts of the side and top surfaces of the radiation heat shield are Q5 and Q6. The calculations are as follows:

[0096]

[0097] Among them, A Leg , A Cover , A Shield and A Ceil are the representative cross-sections of the legs of the stator support frame, the protective cover, the side and top surfaces of the radiation heat shield respectively. T Base , T Cover , T Shield and T Ceil are the temperatures of the base of the stator support frame, the protective cover, the side and top surfaces of the radiation heat shield respectively. In addition, Kg10 represents the thermal conductivity of material G10.

[0098] ​The heat transfer quantity Q of conduction on the upper and lower surfaces of each superconducting coil u and Q L are calculated as follows:

[0099]

[0100] Among them, N Sup represents the number of superconducting coils, A Sup and A L respectively represent the area of the top surface of the superconducting coil and the transverse representative cross-sectional area of the base, and T L is the superconducting temperature.

[0101] The heat transfer quantities Q S and Q V through the current-carrying wires between the vacuum wall and the radiation heat shield and between the radiation heat shield and the rotor are calculated respectively as follows:

[0102]

[0103] Among them, N Forcer and N Leads respectively represent the number of three-phase coils and wires, K Cu and ρ Cu respectively represent the thermal conductivity and resistivity of copper. The heat transfer quantity Q W from the wire to the superconducting coil is as follows:

[0104]

[0105] Step S42: Calculate the heat required for cooling according to the balance relationship of each heat transfer quantity.

[0106] The balance relationship is as follows:

[0107] q3 + N Sup Q U = 0

[0108] Q5 + q2 + q8 = 0

[0109] Q6 - Q s -Q v + q1 + q7 = 0

[0110] Q3 - Q5 = 0

[0111] Q1 + Q3 - q9 - N Sup Q L = 0

[0112] Q m - q4 - q5 - q6 = 0

[0113] The first three equations above refer to the thermal equilibrium on planes 3, 6, and 7 respectively. The fourth and fifth equations represent the equilibrium relationship around the bifurcation point of the protective cover and the base. The last equation represents the equilibrium around the rotor.

[0114] The Joule heat of the rotor coil is as follows:

[0115]

[0116] Where L c and S W are the perimeter of the coil and the cross-sectional area of the coil wire respectively. is the average value of I m , T m is the temperature of the rotor. Additionally, the thickness of the protective cover is small enough, so for simplicity, Q4 = 0.

[0117] The following assumptions are made for the temperature of each surface:

[0118] T1 = T7 = (T Ceil + T Shield ) / 2

[0119] T2 = T8 = (T cover + T Shield ) / 2

[0120] T4 = T5 = T6 = T m

[0121] Solve for the unknowns T Ceil , T Shield , T3, T m , T Base and T Cover through the equilibrium equations to calculate each heat transfer amount.

[0122] Step S43: Determine the refrigeration system according to the heat required for cooling.

[0123] The calculation formula for the AC loss of the superconducting coil is as follows:

[0124]

[0125] Where Q AC is the AC loss of the superconducting coil, the external magnetic field provided by the rotor coil is (B ex , B ez ), is the representative frequency of the external magnetic field, V SC is the volume of the superconductor directly under the rotor, V SC = N coil A coil H s ζ s , N coil and A coil are the average speed of the rotor, the number of turns of the rotor coil, and the projected area of a single turn on the stator surface, respectively. Assume that the external magnetic fields B ex and B ez are respectively much smaller than the penetration fields B px and B pz ,

[0126]

[0127] The calculation process of the external magnetic field of the rotor coil is as follows:

[0128] The shape of the rotor coil is generally racetrack-shaped. For simplicity, assume it is a rectangle with width b m (W m ×L m ×H m ). The calculation formulas for the magnetic fields (B ex , B ey , B ez ) around the coil are as follows:

[0129]

[0130]

[0131] The current density of the rotor coil is The integration intervals are defined as follows:

[0132] X1 = x + W m / 2 X2 = x + W m / 2 - b m X3 = x - W m / 2 + b m X4 = x - W m / 2

[0133] Y1 = y + L m / 2 Y2 = y + L m / / 2 - b m Y3 = y - L m / 2 + b m Y4 = y - L m / 2

[0134] Z1 = z + H m / 2 Z2 = z - H m / 2

[0135] As Figure 14 shown, the integrand f is defined as follows:

[0136]

[0137] The heat quantity Q required to cool the superconducting coil c The calculation formula is as follows:

[0138] Q c = N Sup (Q L + Q U ) + Q W + Q AC ;

[0139] Based on the above calculation results of the heat transfer quantity, the relationship between the heat quantity Q required to cool the superconducting coil c and the temperature of the superconductor is as Figure 15 shown. It can be seen from the figure that Q c is less than the cooling capacity of a commercial single-stage refrigerator.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A low-loss superconducting motor, comprising a vacuum chamber, characterized in that: A stator assembly and a rotor assembly are arranged in a vacuum chamber. A protective cover made of a non-metallic material is arranged between the stator assembly and the rotor assembly to suppress eddy current losses caused by the rotor magnetic field. One of the stator assembly and the rotor assembly is provided with a normal conductor coil, and the other is provided with a superconductor coil. A direct current is applied to the superconductor coil, and an alternating current is applied to the normal conductor coil. A radiation heat shield is arranged in the vacuum chamber opposite to the normal conductor coil, and the temperature of the normal conductor coil is controlled by controlling the emissivity of the radiation heat shield.

2. The low-loss superconducting motor according to claim 1, wherein: The rotor assembly includes a rotor support frame and a plurality of superconductor coils arranged on the rotor support frame. The stator assembly includes a stator support frame and a normal conductor coil arranged on the stator support frame.

3. The low-loss superconducting motor according to claim 2, characterized in that: Both ends of the stator support frame are fixedly connected to both ends of the vacuum chamber. Both ends of the rotor support frame are rotatably connected to both ends of the vacuum chamber through bearings. The superconductor coil and the normal conductor coil are located at the same axial position.

4. A low-loss superconducting motor according to claim 3, characterized in that: The protective cover is sleeved on the circumferential side of the rotor support frame. A radiation heat shield is arranged between the stator support frame and the rotor support frame.

5. A low-loss superconducting motor according to claim 1, characterized in that: The rotor assembly includes a rotor support frame and a plurality of normal conductor coils arranged on the rotor support frame. The stator assembly includes a stator support frame and a superconductor coil arranged on the stator support frame.

6. A design method of a low-loss superconducting motor according to any one of claims 1-5, characterized in that, The specific steps are as follows: Step S1: Calculate the stator magnetic field according to the required acceleration in actual use. Step S2: Calculate the current of the superconductor coil according to the stator magnetic field. Step S3: Calculate the critical current and the superconductor temperature according to the current of the superconductor coil. Step S4: Determine the cooling system according to the superconductor temperature. Specifically, step S4 is: Step S41: Calculate the heat transfer amount, which includes radiative heat transfer amount, conductive heat transfer amount and wire heat transfer amount. Step S42: Calculate the heat required for cooling according to the balance relationship of each heat transfer amount. Step S43: Determine the refrigeration system according to the heat required for cooling.

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