Low-loss superconducting motor and design method thereof

Abstract

The invention discloses a low-loss superconducting motor and a design method thereof, and belongs to the technical field of superconducting motors. A low-loss superconducting motor comprises 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 constant conductor coil, the other one is provided with a superconductor coil, the superconductor coil applies direct current, and the constant conductor coil applies alternating current. Meanwhile, the invention discloses a design method based on the superconducting motor, the low-loss superconducting motor and the design method thereof are adopted, an air gap between the stator assembly and the rotor assembly is small, a high magnetic field is easy to achieve, Joule loss of a common conductor coil is reduced, an air or water cooling pipeline can be omitted, and temperature control is easy.

Description

Technical Field

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

[0002] The winding of a superconducting motor is made of practical superconducting wire. It has the advantages of high power density and high efficiency, and is a very promising motor. Superconducting motors are divided into full superconducting motors and semi-superconducting motors according to their structures. In a full superconducting motor, both the stator and rotor of the motor are superconductors. Both the stator and rotor are installed in an ultra-low temperature constant temperature tank (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 superconductor coil with AC power has large losses, and it is difficult for the rotor to rotate at high speed in the ultra-low temperature constant temperature tank, and it is difficult to cool. A complex mechanical or electrical system is required to achieve safe operation of the motor. In a semi-superconducting motor, one of the stator and rotor of the motor is a superconductor and the other is a normal conductor. One of the stator and rotor is installed in the ultra-low temperature constant temperature tank, and the other is installed outside the ultra-low temperature constant temperature tank. There is an ultra-low temperature constant temperature tank 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 AC magnetic field still exists. Summary of the invention

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

[0004] To achieve the above-mentioned purpose, the present invention provides a low-loss superconducting motor, comprising a vacuum chamber, wherein 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 superconductor coil, a direct current is applied to the superconductor 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 superconductor coils arranged on the rotor support frame, and the stator assembly includes a stator support frame and a conventional conductor coil arranged on the stator support frame.

[0006] Preferably, a plurality of superconductor coils are circumferentially distributed on the inner side of a stator support frame, and two ends of the stator support frame are fixedly connected to two ends of the vacuum chamber; a plurality of conventional conductor coils are circumferentially distributed on the outside of a rotor support frame, and two ends of the stator support frame are fixedly connected to two ends of the vacuum chamber; two ends of the rotor support frame are rotatably connected to two ends of the vacuum chamber through bearings; and the superconductor coils and the conventional 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 shielding cover 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 arranged on the rotor support frame, and the stator assembly includes a stator support frame and a superconductor coil arranged on the stator support frame.

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

[0010] Preferably, the planar structure is covered with multiple layers of thermal insulation films, a protective cover is provided above the array-distributed superconductor coils, the protective cover is made of non-metallic material, and a radiation heat shielding cover is provided on the protective cover.

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

[0012] A design method for a low-loss superconducting motor as described above, comprising the following specific steps:

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

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

[0015] Step S3: Calculating the critical current and the superconductor temperature according to the current of the superconductor 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, which includes radiation heat transfer, conduction heat transfer and wire heat transfer;

[0019] Step S42: Calculating 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, which has the following beneficial effects:

[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, 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, and the air gap between the stator assembly and the rotor assembly is small, so it is easy to achieve a high magnetic field and reduce the Joule loss of the normal conductor coil.

[0023] (2) Air or water cooling pipes can be eliminated and temperature control is easy.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A cross-sectional view of a low-loss superconducting motor embodiment 1 of the present invention;

[0026] Figure 2 A side view of a low-loss superconducting motor embodiment 1 of the present invention;

[0027] Figure 3 A perspective view of a low-loss superconducting motor embodiment 1 of the present invention;

[0028] Figure 4 A cross-sectional view of a low-loss superconducting motor embodiment 2 of the present invention;

[0029] Figure 5 A perspective view of a low-loss superconducting motor embodiment 2 of the present invention;

[0030] Figure 6 This is a distribution diagram of the normal conductor coil of Example 2 of a low-loss superconducting motor of the present invention;

[0031] Figure 7 This is a schematic diagram of the superconductor coil structure of a low-loss superconducting motor embodiment 2 of the present invention;

[0032] Figure 8 It is the relationship curve between the workbench acceleration and the stator magnetic field;

[0033] Fig. 9 is a curve diagram showing the relationship between the current in the superconductor coil and the stator magnetic field;

[0034] Fig.10 is a curve diagram showing the relationship between the superconductor coil temperature and the superconductor coil current;

[0035] Fig.11 Temperature design range diagram for superconductor coil;

[0036] Fig.12 It is the relationship curve between the workbench acceleration and the superconductor coil temperature;

[0037] Fig.13 This is the thermal analysis model diagram in the vacuum chamber;

[0038] Fig.14 This is a diagram of the analysis model of the normal conductor coil in Example 2;

[0039] Fig.15A graph showing the relationship between the amount of heat required for cooling and the temperature of the superconductor coil.

[0040] Reference numerals

[0041] 1. Vacuum chamber; 2. Rotor support frame; 3. Stator support frame; 4. Conventional conductor coil; 5. Superconductor coil; 6. Protective cover; 7. Radiant heat shielding cover. DETAILED DESCRIPTION

[0042] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" 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 a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the 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 circumstances.

[0043] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0044] Example 1

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

[0046] The rotor support frame 2 and the stator support frame 3 are both hollow shaft structures, a plurality of superconductor coils 5 are circumferentially distributed on the inner side of the stator support frame 3, the two ends of the stator support frame 3 are fixedly connected to the two ends of the vacuum chamber 1, a plurality of normal conductor coils 4 are circumferentially distributed on the outer side of the stator support frame 3, and the two ends of the rotor support frame 2 are rotatably connected to the two 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 superconductor coil 5 and the normal conductor coil 4 is greatly reduced, and a high magnetic field is easily achieved. At the same time, applying alternating current to the normal conductor coil 4 and applying direct current to the superconductor coil 5 can control the amplitude of the alternating current, 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 , and the constant conductor coil 4 is cooled by radiation cooling, which can save air or water cooling pipes, and the temperature of the constant conductor coil 4 is controlled by controlling the emissivity of the radiation heat shield 7 .

[0048] Example 2

[0049] The difference between this embodiment and the first embodiment is that the arrangement positions of the normal conductor coil 4 and the superconductor coil 5 are different, and this embodiment is a planar motor. Figure 4-5 As 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 superconductor coil 5 arranged on the stator support frame 3 .

[0050] like Figure 6 As 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 actual conditions, and can also be an irregular shape. In this embodiment, three normal conductor coils 4 form a group of three-phase normal conductor coils 4, and the normal conductor coils 4 are horseshoe-shaped. Four groups 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. Each group of three-phase normal conductor coils 4 is applied with an alternating current with a phase difference of 120 degrees.

[0051] The number of the normal conductor coils 4 in each group of the normal conductor coils 4 can also be adjusted according to the actual situation, such as two phases or four phases, and 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, on which a plurality of array-distributed superconductor coils 5 are arranged. Figure 7 As shown, the superconductor coil 5 has a height H s The cylindrical coils 5 have different vertical polarities of adjacent superconductor coils 5, that is, N poles and S poles are arranged alternately. In this embodiment, 36 N poles and 25 S poles are provided.

[0053] The planar structure is covered with a multi-layer thermal insulation film to suppress the radiant heat from the inner wall of the vacuum chamber 1 to maintain a low surface emissivity. The stator support frame 3 is made of G10 material, which 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 actual performance. A protective cover 6 is arranged above the array-distributed superconductor coil 5. The protective cover 6 is made of non-metallic material to suppress eddy current losses caused by the rotor magnetic field. The surface emissivity must be set to a larger value in order to cool the normal conductor coil 4. A radiant heat shield 7 is arranged on the protective cover 6.

[0054] The air gap length of a conventional 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, the specific steps are as follows:

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

[0057] The superconductor coils are arranged periodically with a spacing of 2τ. The magnetic field generated by the superconductor coil array has an amplitude of B s , the fundamental wave with a period of 2τ, then the amplitude is I m The current with 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 )as follows:

[0058] F x =(3 / 2)KI m sin(φ)

[0059] F z =-(3 / 2)KI m cos(φ) (1)

[0060] The formula for the force constant K is as follows:

[0061]

[0062] α=πb m / 2τ,L m , b m 、N m as well as are the length, width, number of turns and filling factor of the constant conductor coil on the rotor support frame;

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

[0064] Depending on the number and arrangement of the three-phase coils on the rotor assembly, the relationship between the table acceleration and the force produced 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-axis 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 constant conductor coil current I m .

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

[0069] like Figure 8 As shown, for the constant conductor coil current I 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 the conventional motor, the air gap length of the stator assembly and the rotor assembly proposed in this embodiment is smaller, so it is easy to increase the stator magnetic field B proposed in this embodiment. s .

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

[0072] Stator magnetic field (B x , B z ) is calculated as follows:

[0073]

[0074] The function being integrated is as follows:

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

[0076]

[0077] in,

[0078] C=Zz J s =N s I s / (b s H s ) η=sinθ ξ=cosθ

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

[0080] The current in the superconductor 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 Compared with the conventional motor, the air gap length between the stator assembly and the rotor assembly proposed in this embodiment is smaller, such as Fig. 9 As shown, the relationship curve between the current in the superconductor coil and the stator magnetic field shows that the stator magnetic field proposed in this embodiment can be generated by a smaller superconducting current. Step S3: Calculate the critical current and the superconductor temperature according to the current of the superconductor coil.

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

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

[0083]

[0084] Among them, T s is the superconductor temperature, V s is the area of ​​the superconductor coil.

[0085] The relationship between the superconductor coil temperature and the superconductor coil current is as follows: Fig.10 As shown in Figure 2. The cooling capacity of a cryogenic cooler decreases as the temperature decreases. Fig.11 As shown, the temperature of the superconductor coil is therefore set at 20 K to 45 K. If a single-stage refrigerator with a larger cooling capacity can be used within this temperature range, this increases the advantage of superconducting magnets over permanent magnets.

[0086] like Fig.12 As shown in the figure, the relationship between the workbench acceleration and the temperature of the superconductor coil is shown. m >0.5I0, the superconducting motor proposed in the present invention can obtain a larger workbench acceleration than the traditional motor.m When the value 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 temperature of the superconductor.

[0089] The internal thermal analysis model of the motor in this embodiment is as follows: Fig.13 As shown, the interior is composed of N planes, where N = 12.

[0090] Step S41: Calculate the heat transfer, which includes radiation heat transfer, conduction heat transfer and wire heat transfer.

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

[0092] q=RP -1 S

[0093]

[0094] R[R ij ]

[0095] P=[P ij ] r i =(1-ε i ) / ε i

[0096] Among them, ε i and T j Plane j The emissivity and temperature of the , σ is the Boltzmann constant, F ij is the shape coefficient from plane i to plane j. T 10 =T 11 =T 12 =T H (Room temperature).

[0097] The conduction heat transfer of the legs and base of the stator support frame is Q1 and Q3, and the conduction heat transfer of the side and top surfaces of the radiation heat shield is Q5 and Q6, which are calculated as follows:

[0098]

[0099] Among them, A Leg , A Cover , A Shield and A CeilRepresentative cross-sections of the stator support legs, protective cover, and radiant heat shield side and top surfaces, respectively. Base 、T Cover 、T Shield and T Ceil are the temperatures of the stator support frame base, protective cover, side and top surfaces of the radiation heat shield cover, respectively. In addition, Kg10 represents the thermal conductivity of material G10.

[0100] The conduction heat Q of the upper and lower surfaces of each superconductor coil u and Q L The calculation of is as follows:

[0101]

[0102] Among them, N Sup represents the number of superconductor coils, A Sup and A L represent the area of ​​the top surface of the superconductor coil and the lateral representative cross-sectional area of ​​the base, respectively. L Superconductor temperature.

[0103] Heat transfer Q through the current conductors between the vacuum wall and the radiation heat shield and between the radiation heat shield and the rotor S and Q V The calculations are as follows:

[0104]

[0105] Among them, N Forcer and N Leads Respectively represent the number of three-phase coils and wires, K Cu and ρ Cu They represent the thermal conductivity and resistivity of copper, and the amount of heat transferred from the wire to the superconductor coil, Q W as follows:

[0106]

[0107] Step S42: Calculate the heat required for cooling according to the balance relationship of each heat transfer amount.

[0108] The equilibrium relationship is as follows:

[0109] q3+N Sup Q U =0

[0110] Q5+q2+q8=0

[0111] Q6-Q s -Q v +q1+q7=0

[0112] Q3-Q5=0

[0113] Q1+Q3-q9-N Sup Q L =0

[0114] Q m -q4-q5-q6=0

[0115] The first three formulas above refer to the thermal balance on planes 3, 6 and 7 respectively. The fourth and fifth formulas represent the balance relationship around the bifurcation point between the protective cover and the base. The last formula represents the balance around the rotor.

[0116] The Joule heating of the rotor coil is as follows:

[0117]

[0118] Among them, L c and S W are the circumference of the coil and the cross-sectional area of ​​the coil wire, respectively. For I m The average value of T m is the temperature of the rotor. In addition, the thickness of the protective cover is small enough, so for simplicity, Q4=0.

[0119] The following assumptions are made about the temperature of each surface:

[0120] T1=T7=(T Ceil +T Shield ) / 2

[0121] T2=T8=(T cover +T Shield ) / 2

[0122] T4=T5=T6=T m

[0123] Solve the unknown T by using the equilibrium formula Ceil 、T Shield , T3, T m 、T Base and T Cover To calculate the heat transfer.

[0124] Step S43: Determine the refrigeration system according to the heat required for cooling.

[0125] The calculation formula of AC loss of superconductor coil is as follows:

[0126]

[0127] Among them, Q AC is the AC loss of the superconductor coil, and the external magnetic field provided by the rotor coil is (B ex , Bez ), is the representative frequency of the external magnetic field, V SC The volume of superconductor directly below 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 rotor coils and the projected area of ​​a single coil on the stator surface. Assuming that the external magnetic field B ex and B ez are sufficiently smaller than the penetration field B of the superconductor px and B pz ,

[0128]

[0129] The external magnetic field calculation process of the rotor coil is as follows:

[0130] The shape of the rotor coil is generally a racetrack, but for simplicity, it is assumed that the width is b. m The rectangle (W m ×L m ×H m ), the magnetic field around the coil (B ex , B ey , B ez ) is calculated as follows:

[0131]

[0132]

[0133] The current density of the rotor coil is The integration interval is defined as follows:

[0134] X1=c+W m / 2 X2=x+W m / 2-b m X3=xW m / 2+b m X4=xW m / 2

[0135] Y1=y+L m / 2 Y2=y+L m / 2-b m Y3=yL m / 2+b m Y4=yL m / 2

[0136] Z1=z+H m / 2 Z2=zH m / 2

[0137] like Fig.14 As shown, the definition of the integrand f is as follows:

[0138]

[0139] The heat required to cool the superconductor coil Q c The calculation formula is as follows:

[0140] Q c =N Sup (Q L +Q U )+Q W +Q AC ;

[0141] Based on the above calculation results of heat transfer, the heat required to cool the superconductor coil is Q c The relationship between the temperature of the superconductor is as follows Fig.15 As shown in the figure, Q c Less than the cooling capacity of a commercial single-stage chiller.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution 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 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 superconductor coil, a direct current is applied to the superconductor coil, and an alternating current is applied to the normal conductor coil.

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

3. A low-loss superconducting motor according to claim 2, characterized in that: A plurality of superconductor coils are circumferentially distributed on the inner side of a stator support frame, and two ends of the stator support frame are fixedly connected to two ends of a vacuum chamber. A plurality of conventional conductor coils are circumferentially distributed on the outside of a rotor support frame, and two ends of the stator support frame are fixedly connected to two ends of the vacuum chamber. Two ends of the rotor support frame are rotatably connected to two ends of the vacuum chamber through bearings. The superconductor coil and the conventional 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, and a radiation heat shielding cover 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 comprises a rotor support frame and a plurality of normal conductor coils arranged on the rotor support frame, and the stator assembly comprises a stator support frame and a superconductor coil arranged on the stator support frame.

6. A low-loss superconducting motor according to claim 5, characterized in that: The top of the stator support frame is a planar structure, on which a plurality of superconductor coils distributed in an array are arranged, and the vertical polarities of adjacent superconductor coils are different.

7. A low-loss superconducting motor according to claim 6, characterized in that: The planar structure is covered with multiple layers of thermal insulation film, and a protective cover is arranged above the array-distributed superconductor coils. The protective cover is made of non-metallic material and a radiation heat shielding cover is arranged on the protective cover.

8. The low-loss superconducting motor according to claim 5, characterized in that: The rotor support frame is a frame-shaped structure, in which at least one group of normal conductor coils is arranged, and each group of normal conductor coils includes at least two normal conductor coils.

9. A method for designing a low-loss superconducting motor according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: Step S1: Calculate the stator magnetic field according to the actual required acceleration; Step S2: Calculating the current of the superconductor coil according to the stator magnetic field; Step S3: Calculating the critical current and the superconductor temperature according to the current of the superconductor coil; Step S4: Determine the cooling system according to the temperature of the superconductor.

10. The design method according to claim 9, characterized in that: Step S4 is specifically as follows: Step S41: Calculate the heat transfer, which includes radiation heat transfer, conduction heat transfer and wire heat transfer; Step S42: Calculating 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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