A 36-slot 28-pole range extender generator for electric aircraft

Abstract

This invention discloses a 36-slot, 28-pole range extender generator for electric aircraft. It adopts an internal rotor with 36 slots, 28 poles, and a four-section rotor core with radially inserted skewed magnets. It features symmetrical magnetomotive force waveform, high winding coefficient, low torque pulsation and cogging torque, and no end-circulating current. The motor adopts a centralized winding, winding oil cooling, and shell water cooling method, making it suitable for use as a range extender generator for electric aircraft.

Description

[Technical Field]

[0001] This invention belongs to the field of motor technology, and in particular relates to a 36-slot 28-pole range extender generator for electric aircraft. [Background Technology]

[0002] With the rapid development of the low-altitude economy, the demand for extended range in electric propulsion aircraft is increasing. Current eVTOL aircraft are limited by the weight of the battery packs that can be installed, with a range generally less than 200 kilometers. Range extenders can be used to extend the range.

[0003] Therefore, it is necessary to provide a new 36-slot 28-pole range extender generator for electric aircraft to solve the above-mentioned technical problems. [Summary of the Invention]

[0004] The main objective of this invention is to provide a 36-slot, 28-pole range extender generator for electric aircraft, which has excellent performance characteristics such as symmetrical magnetomotive force waveform, high winding coefficient, low torque pulsation and cogging torque, and no end-circulating current.

[0005] The present invention achieves the above-mentioned objective through the following technical solution: a 36-slot 28-pole range extender generator for electric aircraft, comprising a stator and a rotor disposed inside the stator; the stator comprises a stator core and windings, the inner wall of the stator core having a plurality of stator slots arranged at equal angles along its circumference, each stator slot containing the windings; the rotor comprises a rotor core and a set of magnets, the outer wall of the rotor core having a plurality of receiving cavities arranged at equal angles along its circumference, each receiving cavity containing a set of magnets;

[0006] The stator has 36 slots and the magnet assembly has 28, forming a 36-slot, 28-pole configuration.

[0007] The winding adopts a concentrated winding;

[0008] The stator core has an outer diameter D1 = 370 mm and an inner diameter D2 = 298 mm.

[0009] The outer diameter of the rotor core is D3 = 295 mm and the inner diameter is D4 = 272 mm.

[0010] The air gap L1 between the stator and the rotor is 1.5 mm;

[0011] The stator slot has a slot opening width L2 = 6 mm, a slot depth L3 = 29.5 mm, a slot tip angle θ1 = 35°, and the stator slot is a parallel slot with a parallel slot width L4 = 15 mm.

[0012] The rotor adopts a four-segment skewed pole treatment, with skewed pole treatment angles of -0.5358°, -0.1786°, 0.1786°, and 0.5357° respectively.

[0013] Furthermore, stator teeth are formed between two adjacent stator slots, and the air gap is formed between the inner wall of the stator teeth and the outer wall of the magnet assembly.

[0014] Furthermore, the main cross-sectional shape of the stator slot is rectangular, and an inwardly recessed slot is formed on the side near the inner wall of the stator core, with the inwardly recessed profile being a straight line; the slot tip angle is the inclination angle of the inwardly recessed profile.

[0015] Furthermore, the polar arc angle θ2 = 160°.

[0016] Furthermore, the magnets in the magnet assembly have a thickness L5 = 5.5 mm and are inserted into the receiving cavity in a radial insertion manner.

[0017] Furthermore, the magnet is a 52UH neodymium iron boron magnet with a remanence of 1.46T and a maximum operating temperature of 180℃.

[0018] Furthermore, the group of magnets forms a pole, and the pole includes 10 magnets.

[0019] Furthermore, the winding is made of 240℃ temperature-resistant, corona-resistant polyimide copper flat wire, with 6 turns per wire.

[0020] Furthermore, the stator slot filling rate is 89.56%.

[0021] Furthermore, the stator slot is provided with insulating paper that isolates the inner wall of the stator slot from the winding; the insulating paper is 0.25mm thick DuPont Nomex T410 aramid insulating paper; the gap of the winding in the stator slot is filled with insulating varnish, the insulating varnish being VX4201 unsaturated polyesterimide resin.

[0022] Furthermore, the stator core and the rotor core are made of Baosteel B0AV1000 silicon steel sheets with a thickness of 0.1mm, and the stack height of the stator core and the rotor core is 38mm, with a stacking coefficient of 0.97.

[0023] Furthermore, a cooling shell is provided on the outer periphery of the stator, and a cooling medium circulates within the cooling shell.

[0024] Furthermore, an inner retaining ring is provided on the inner side of the rotor, and a cooling cavity is formed between the inner retaining ring and the cooling housing, which encloses the stator and the rotor. The upper and lower ends of the cooling cavity are sealed by end caps; a cooling medium circulates within the cooling cavity.

[0025] Compared with existing technologies, the beneficial effects of the 36-slot, 28-pole range extender generator for electric aircraft of this invention are as follows: Through optimized design in key aspects such as motor material selection, magnet arrangement, skewed pole treatment, and winding form, it is applied to electric propulsion aircraft. The use of an inner rotor, 36 slots, 28 poles, and a four-segment rotor core with radially inserted skewed magnets results in symmetrical magnetomotive force waveform, high winding coefficient, low torque pulsation and cogging torque, and no end-circulating current. The motor employs centralized winding, oil-cooled windings, and water-cooled casing. It generates 770V, 350A, with a stack height of 38mm, an electromagnetic component weight of 15.12 kg, a motor weight of approximately 25 kg, a generator power of 260KVA, and a generator power density as high as 10.4KVA / kg. [Attached Image Description]

[0026] Figure 1 This is a schematic diagram of the horizontal cross-sectional structure according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the winding in the stator slot in an embodiment of the present invention;

[0028] Figure 3 This is a partial structural diagram in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the longitudinal cross-sectional structure of an embodiment of the present invention;

[0030] Figure 5 This is a magnetomotive force waveform diagram of a motor using a 36-slot, 28-pole configuration according to an embodiment of the present invention.

[0031] Figure 6 This is a histogram of the winding coefficient distribution of a motor with a 36-slot, 28-pole configuration according to an embodiment of the present invention.

[0032] Figure 7 The BH curve diagram of B10AV1000 silicon steel sheet (0.1mm) in an embodiment of the present invention;

[0033] Figure 8 This is a diagram showing the remanence, coercivity, and squareness coefficient Hk / Hcj of the N52UH magnet in this embodiment of the invention.

[0034] Figure 9 This is an electromagnetic simulation data diagram under 6000 rpm power in an embodiment of the present invention;

[0035] Figure 10 This is a magnetic induction density cloud map under 6000 rpm electric power in an embodiment of the present invention;

[0036] Figure 11This is a diagram showing the magnetic induction intensity of various parts under a 6000 rpm power output in an embodiment of the present invention.

[0037] Figure 12 This is a loss distribution diagram obtained from simulation at 6000 rpm in an embodiment of the present invention;

[0038] Figure 13 This is a torque curve obtained from simulation at 6000 rpm in an embodiment of the present invention.

[0039] Figure 14 This is a MAP diagram of efficiency obtained from simulation at 6000 rpm in an embodiment of the present invention.

[0040] Figure 15 This is a thermal simulation result diagram of 6000 rpm power in an embodiment of the present invention;

[0041] Figure 16 This is a simulation data graph showing the minimum starting torque in an embodiment of the present invention;

[0042] Figure 17 This is a magnetic induction density cloud map under maximum torque in an embodiment of the present invention;

[0043] Figure 18 This is a diagram showing the magnetic induction intensity of each part under the maximum torque in an embodiment of the present invention;

[0044] Figures 19-20 This is a simulation diagram of rotor strength in an embodiment of the present invention;

[0045] Figure 21 This is a simulation result diagram of the cogging torque and torque pulsation during 6000 power-on cycles in Embodiment 6 of the present invention;

[0046] Figure 22 This is a 2D spectrum of the time-dominant stator radial harmonics according to an embodiment of the present invention;

[0047] Figure 23 This is a Campbell sound pressure field spectrum diagram according to an embodiment of the present invention;

[0048] Figure 24 This is a diagram showing the stator radial stress data of an embodiment of the present invention;

[0049] Figure 25-26 This is a diagram showing the phase current curve and generation voltage curve of an embodiment of the present invention;

[0050] The numbers in the diagram represent:

[0051] 100-36-slot 28-pole range extender generator for electric aircraft;

[0052] 1-Stator, 11-Stator core, 111-Stator slot, 112-Stator tooth, 113-Insulating paper, 114-Insulating varnish, 12-Winding; 2-Rotor, 21-Rotor core, 22-Magnet assembly; 3-Cooling housing, 31-Cooling channel; 4-Inner retaining ring, 41-Cooling cavity, 42-End cover.

Detailed Implementation Methods

[0053] Example 1:

[0054] Please refer to Figures 1-4 This embodiment is a 36-slot 28-pole range extender generator 100 for electric aircraft, which includes a stator 1, a rotor 2 disposed inside the stator 1, and a heat sink 3 disposed outside the stator 1.

[0055] The stator 1 includes a stator core 11 and windings 12. The inner wall of the stator core 11 has a plurality of stator slots 111 arranged at equal angles along its circumference, and each stator slot 111 contains a winding 12. Stator teeth 112 are formed between adjacent stator slots 111. The outer diameter D1 of the stator core 11 is 370 mm, and the inner diameter D2 of the stator core 11 is 298 mm.

[0056] The rotor 2 includes a rotor core 21 and a magnet assembly 22. The outer wall of the rotor core 21 has several accommodating cavities (not shown in the figure) arranged at equal angles along its circumference, and each accommodating cavity contains a set of magnet assemblies 22. The outer diameter D3 of the rotor core 21 is 295 mm, and the inner diameter D4 of the rotor core 21 is 272 mm.

[0057] The air gap L1 between stator 1 and rotor 2 is 1.5mm, which is the distance between the outer wall of magnet assembly 22 and the inner wall of stator core 11. The main cross-sectional shape of stator slot 111 is rectangular, and an inwardly tapered slot is formed on the side near the inner wall of stator core 11. The inwardly tapered profile is a straight line, and the slot width L2 = 6mm. The slot depth L3 = 29.5mm, and the inclination angle of the inwardly tapered profile, i.e., the slot tip angle θ1 = 35°, are all parallel slots with a parallel slot width L4 = 15mm. The pole arc angle θ2 = 160°, and the magnet thickness L5 = 5.5mm. The magnets are 52UH neodymium iron boron magnets with a remanence of 1.46T and a maximum operating temperature of 180℃. They are inserted into the receiving cavity using a radial insertion method.

[0058] The more stator slots 111 there are, the lower the motor's harmonic content, effectively reducing additional losses and harmonic leakage reactance, making the magnetomotive force waveform closer to a sine wave, which is beneficial for increasing motor torque. Additionally, the increased total heat dissipation area around the coils in the slots facilitates heat dissipation and reduces temperature rise. The design of the rotor slot number must be matched with the stator slot number. Improper slot matching may lead to motor failure to start, excessive vibration and noise, and additional losses and torque. In this embodiment, the motor uses 36 slots and 28 poles. That is, the number of stator slots 111 on the stator core 11 is 36. The number of magnet groups 22 on the outer wall of the rotor core 21 is 28, forming 28 poles. Please refer to... Figure 5-6 , Figure 5 This is a stacked diagram of the waveform height of a 36-slot, 28-pole magnetomotive force. Figure 6 For the coefficient histogram of a 36-slot, 28-pole winding, from Figure 5 As can be seen, the combination of 36 slots and 28 poles effectively avoids end-circulating heat generation; from Figure 6 As can be seen, the combination of 36 slots and 28 poles results in a high winding coefficient.

[0059] In this embodiment, one pole consists of 10 magnets. By segmenting the magnets into 10 sections, the eddy current losses and heat generation during motor operation can be effectively reduced. In this embodiment, N52UH neodymium iron boron magnets are used. Information on the remanence, coercivity, and squareness coefficient Hk / Hcj of the N52UH neodymium iron boron magnets is as follows: Figure 8 As shown. From Figure 8 As can be seen from this, N52UH neodymium iron boron magnets can be used for a long time within the range of 180℃, with a square coefficient greater than 0.95 and a remanence Br of 1.46T.

[0060] To ensure sufficient starting torque, the current density cannot be too low, while excessive current density will increase slip, rotor resistance loss, efficiency, and heat generation. In this embodiment, winding 12 is wound in a concentrated single-winding configuration using 240℃ corona-resistant polyimide copper flat wire. The concentrated winding consists of 6 turns per wire. This concentrated winding effectively reduces the end height, thereby reducing copper loss and heat generation during motor operation.

[0061] The stator slot 111 has a fill rate of 89.56% (including insulating paper). If the slot fill rate is too high, the winding will not be able to fit into the slot; if the slot fill rate is too low, the slot utilization rate will be too low, which is not conducive to the heat dissipation of the winding. In this embodiment, the fill rate of the stator slot 111 is designed to be 89.56%, which, together with the subsequent design of the stator slot 111 dimensions, ensures both the feasibility of winding copper flat wire and good heat dissipation performance.

[0062] The insulating paper 113 inside the stator slot 111 is made of 0.25mm thick DuPont Nomex T410 aramid insulating paper. The gaps of the winding 12 in the stator slot 111 are filled with insulating varnish 114, which is made of VX4201 unsaturated polyesterimide resin as the slot filling material.

[0063] Rotor 2 is skewed, specifically using a four-segment skew design with angles of -0.5358°, -0.1786°, 0.1786°, and 0.5357°. By employing segmented skewed design with set angles on the rotor, the motor's torque ripple and cogging torque are reduced; motor vibration and noise are also reduced.

[0064] In this embodiment, the stator core 11 and the rotor core 21 are made of 0.1mm thick Baosteel B10AV1000 silicon steel sheets, and the stacking height of the stator core 11 and the rotor core 21 is 38mm, with a stacking factor of 0.97. Please refer to... Figure 7 , Figure 7 The BH curve of B10AV1000 silicon steel sheet (0.1mm) shows the relationship between magnetic induction and magnetic field strength during the magnetization process. It can be seen from the figure that the saturation point is greater than 2.1T (unextrapolated curve).

[0065] A cooling housing 3 is provided on the outer periphery of the stator 1. The cooling housing 3 surrounds the outer periphery of the stator 1. A cooling channel 31 is formed inside the cooling housing 3. A cooling medium, such as water, circulates in the cooling channel 31.

[0066] An inner retaining ring 4 is provided on the inner side of the rotor 2. A cooling cavity 41 is formed between the inner retaining ring 4 and the cooling housing 3, which encloses the stator 1 and the rotor 2. The upper and lower ends of the cooling cavity 41 are sealed by end caps 42. A cooling medium, such as ATF cooling oil, circulates in the cooling cavity 41.

[0067] To verify that the motor designed in this embodiment has excellent performance, thermal simulation tests and electromagnetic simulation tests were conducted on the motor, as follows:

[0068] (1) Electromagnetic simulation under 6000 rpm:

[0069] Electromagnetic simulation input conditions: Current input 350A, voltage input 770V, lead angle set to 40°, winding copper wire temperature set to 175℃, magnet temperature set to 155℃, shaft temperature set to 105℃, maximum speed 6000rpm, iron loss coefficient Ka set to 2.2; electrical load, electrical density, and thermal equivalent: 136.025A / mm, 16.59A / mm 2 2256.656A2 / mm 3After thermal equilibrium, the average temperature of the winding was 152.9℃, the highest temperature was 172.1℃, and the temperature of the magnet was 58.1℃.

[0070] The electromagnetic simulation results at 6000 rpm are as follows: Figure 9 As shown in the figure. The simulation results show that the generated torque is 377.9 Nm, the maximum efficiency is 96.52%, and the total loss is 8559.4 W.

[0071] Magnetic induction density cloud map under 6000 rpm is shown below Figure 10 As shown; the magnetic induction intensity of each part is as follows Figure 11 As shown. Simulation results show that the maximum magnetic flux density is located at the tooth section, with a maximum of 2.06T. The average magnetic flux density in the air gap is 0.6644T, and the maximum magnetic flux density in the air gap is 1.406T.

[0072] The loss distribution obtained from the simulation at 6000 rpm is as follows: Figure 12 As shown.

[0073] The torque curve obtained from the simulation at 6000 rpm is as follows: Figure 13 As shown in the figure. Simulation results show that a minimum torque of 377.9 Nm is required at 6000 kW, and the power generation efficiency is 96.52%.

[0074] The efficiency MAP obtained from the simulation at 6000 rpm is shown below. Figure 14 As shown in the figure, the simulation results (MAP) for peak power show that the motor efficiency is greater than 96% in the speed range of 3000rpm to 6000rpm.

[0075] (2) Thermal simulation at 6000 rpm:

[0076] Thermal simulation input conditions: Cooling water inlet temperature 55℃, cooling ATF oil inlet temperature 55℃, water flow rate 30 liters per minute, ATF oil flow rate 24 liters per minute.

[0077] The simulation results of 6000 rpm electric thermal simulation are as follows: Figure 15 As shown in the figure. The simulation results show that thermal equilibrium is reached within 10 minutes, with the highest temperature of the winding reaching approximately 172.1℃ and the magnet reaching approximately 58.1℃. There is no risk of winding burnout or magnet demagnetization.

[0078] (3) Simulation of minimum starting torque:

[0079] Simulation input conditions: magnet and winding temperature 20℃, current 350A, voltage 770V, lead angle 40°.

[0080] The simulation results of minimum starting torque are as follows: Figure 16 As shown in the figure. The results show that the minimum starting torque is 423.41 Nm, the cogging torque is 2.3551 Nm, and the torque ripple is 2.595%.

[0081] The magnetic flux density cloud diagram at maximum torque is shown below. Figure 17 As shown, the magnetic induction intensity of each part is as follows Figure 18 As shown in the figure. Simulation results show that at startup, the highest magnetic induction intensity is 2.102T, the maximum air gap magnetic flux density is 1.445T, and the average is 0.7516T.

[0082] (4) Rotor strength simulation:

[0083] The rotor strength simulation results are as follows Figures 19-20 As shown in the figure. The results show that at 6000 rpm, the rotor did not reach the yield point of 452 MPa for the B10AV1000 material, and the actual maximum stress was only 112 MPa.

[0084] (5) NVH performance test: Simulation results of cogging torque and torque pulsation at 6000 rpm are as follows: Figure 21 As shown in the figure. Simulation results show that with a four-segment rotor skewed pole treatment, the torque ripple is 3.5%, and the cogging torque is only 1.84 Nm.

[0085] (6) Time-dominant stator radial harmonic 2D spectrum, such as Figure 22 As shown in the diagram, the 2D harmonic spectrum of the stator radial force shows smooth and rounded peaks, which avoids the problem of whistling during motor operation.

[0086] (7) Campbell's sound pressure field spectrum, such as Figure 23 As shown in the figure. The results show that spatial orders 6 and 12 correspond to NVH abnormalities in the frequency range of 3200-4800 Hz, and correspond to speeds above 16000 rpm.

[0087] (8) Stator radial stress data, such as Figure 24 As shown.

[0088] (9) The phase current curve and the generation voltage curve are respectively as shown in Figure 1. Figure 25 , 26 As shown in the figure, the peak phase current at 6000 revolutions per minute is 494.9A and the peak generation voltage is 770V.

[0089] For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this invention, and these all fall within the protection scope of this invention.

Claims

1. A 36-slot, 28-pole range extender generator for electric aircraft, comprising a stator and a rotor disposed inside the stator; the stator comprising a stator core and windings, wherein the inner wall of the stator core is provided with a plurality of stator slots at equal angles along its circumference, and each stator slot is provided with the windings; the rotor comprising a rotor core and a set of magnets, wherein the outer wall of the rotor core is provided with a plurality of receiving cavities at equal angles along its circumference, and each receiving cavity is provided with a set of magnets; characterized in that: The stator has 36 slots and the magnet assembly has 28, forming a 36-slot, 28-pole configuration. The winding adopts a concentrated winding; The stator core has an outer diameter D1 = 370 mm and an inner diameter D2 = 298 mm. The outer diameter of the rotor core is D3=295mm and the inner diameter is D4=272mm. The air gap L1 between the stator and the rotor is 1.5 mm; The stator slot has a slot opening width L2=6mm, a slot depth L3=29.5mm, a slot tip angle θ1=35°, and the stator slot is a parallel slot with a parallel slot width L4=15mm. The rotor adopts a four-segment skewed pole treatment, with skewed pole treatment angles of -0.5358°, -0.1786°, 0.1786°, and 0.5357° respectively.

2. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1, wherein: Stator teeth are formed between two adjacent stator slots, and the air gap is formed between the inner wall of the stator teeth and the outer wall of the magnet assembly.

3. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1 wherein: The pole arc angle θ2 of the rotor magnet is 160°.

4. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1, wherein: The magnets in the magnet assembly have a thickness L5 = 5.5 mm and are inserted into the receiving cavity in a radial insertion manner.

5. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1 wherein: The magnet is made of 52UH neodymium iron boron magnet with a remanence of 1.46T and a maximum operating temperature of 180℃.

6. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1 wherein: The group of magnets forms a pole, and the pole includes 10 magnets.

7. The 36-slot 28-pole range extender generator for electric aircraft as described in claim 1, characterized in that: The winding is made of 240℃ temperature-resistant, corona-resistant polyimide copper flat wire, with 6 turns per wire.

8. The 36-slot 28-pole range extender generator for electric aircraft as described in claim 1, characterized in that: The stator slot filling rate is 89.56%.

9. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1 wherein: The stator slot is provided with insulating paper that isolates the inner wall of the stator slot from the winding; the insulating paper is 0.25mm thick DuPont Nomex T410 aramid insulating paper; the gap of the winding in the stator slot is filled with insulating varnish, which is VX4201 unsaturated polyesterimide resin.

10. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1, wherein: The stator core and the rotor core are made of Baosteel B0AV1000 silicon steel sheets with a thickness of 0.1mm, and the stack height of the stator core and the rotor core is 38mm, with a stacking coefficient of 0.

97.

11. The 36-slot, 28-pole range extender generator for electric aircraft of claim 1, wherein: A cooling shell is provided on the outer periphery of the stator, and a cooling medium circulates within the cooling shell.

12. The 36-slot, 28-pole range extender generator for electric aircraft of claim 11, wherein: An inner retaining ring is provided on the inner side of the rotor, and a cooling cavity is formed between the inner retaining ring and the cooling housing, which encloses the stator and the rotor. The upper and lower ends of the cooling cavity are sealed by end caps. Cooling medium circulates in the cooling cavity.

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