Range extender generator for 12000-turn electric aircraft

Abstract

The invention discloses a 12000-turn range extender generator for an electric aircraft, which adopts a mode of 24-slot and 20-pole inner rotor and radial insertion of seven-section rotor iron core skewed slot magnetic steel, and has the excellent performances of symmetrical magnetomotive force waveform, high winding coefficient, low torque ripple and cogging torque and no end ring current. The motor adopts a centralized winding, winding oil cooling and shell water cooling mode, and is suitable for a generator for a range extender of an electric aircraft.

Description

[Technical field]

[0001] The invention belongs to the technical field of motors, and in particular relates to a 12,000-rpm range extender generator for electric aircraft. [Background technology]

[0002] As the low-altitude economy develops faster and faster, electric propulsion aircraft have higher and higher requirements for extending their range. The current eVTOL aircraft range is limited by the weight of the battery pack that can be installed, and the range is generally less than 200 kilometers. The use of a range extender can extend the range.

[0003] Therefore, it is necessary to provide a new 12,000-rpm range extender generator for electric aircraft to solve the above technical problems. [Summary of the invention]

[0004] The main purpose of the present invention is to provide a 12000 rpm range extender generator for electric aircraft, which has the excellent performance of symmetrical magnetomotive force waveform, high winding coefficient, low torque pulsation and cogging torque, and no end circulation.

[0005] The present invention achieves the above-mentioned object through the following technical solutions: a 12000-rpm range extender generator for electric aircraft, comprising a stator and a rotor arranged inside the stator; the stator comprises a stator core and a winding, the inner wall of the stator core is provided with a plurality of stator slots at equal angles along its own circumference, and each of the stator slots is provided with the winding; the rotor comprises a rotor core and a magnetic steel group, the outer wall of the rotor core is provided with a plurality of accommodating cavities at equal angles along its own circumference, and each of the accommodating cavities is provided with a group of magnetic steel groups;

[0006] The number of the stator slots is 24, and the number of the magnetic steel groups is 20, forming a matching structure of 24 slots and 20 poles;

[0007] The winding adopts concentrated winding;

[0008] The stator core has an outer diameter D1 of 262 mm and an inner diameter D2 of 202 mm;

[0009] The outer diameter D3 of the rotor core is 198 mm, and the inner diameter D4 is 170 mm;

[0010] The air gap between the stator and the rotor is L1=2 mm;

[0011] The stator slot has a slot width L2=3 mm, a slot depth L3=21 mm, a slot tip angle θ1=30°, and the stator slot is a parallel slot with a parallel slot width L4=15 mm;

[0012] The rotor adopts seven-stage tilted pole treatment, and the tilted pole treatment angles are: -1.28571°, -0.857143°, -0.428571°, 0°, 0.428571°, 0.857143°, and 1.28571°.

[0013] Furthermore, a stator tooth is formed between two adjacent stator slots, and the air gap is formed between the inner wall of the stator tooth and the outer wall of the magnetic steel group.

[0014] Furthermore, the main cross-section of the stator slot is rectangular, and a retracted slot opening is formed on one side close to the inner wall of the stator core, and the retracted profile is a straight line; the slot tip angle is the inclination angle of the retracted profile.

[0015] Furthermore, the pole arc angle θ2 = 168°.

[0016] Furthermore, the thickness of the magnetic steel in the magnetic steel group is L5=6 mm, and the magnetic steel is inserted into the accommodating cavity in a radial insertion manner.

[0017] Furthermore, the magnetic steel adopts 52UH NdFeB magnetic steel with a remanence of 1.46T and a maximum operating temperature of 180°C.

[0018] Furthermore, the group of magnetic steel groups forms a pole, and the pole includes 20 magnetic steels.

[0019] Furthermore, the winding is made of corona-resistant polyimide copper rectangular wire with a temperature resistance grade of 240° C., and a single wire is wound with 7 turns.

[0020] Furthermore, the filling rate of the stator slots is 88.72%.

[0021] Furthermore, the stator slot is provided with insulating paper for isolating the inner wall of the stator slot from the winding; the insulating paper is made of DuPont Nomex T410 aramid insulating paper with a thickness of 0.25 mm; the gap of the winding in the stator slot is filled with insulating varnish, and the insulating varnish is made of VX4201 unsaturated polyester imide resin.

[0022] Furthermore, the stator core and the rotor core are formed by stacking JFE10JNX900 silicon steel sheets with a thickness of 0.1 mm, the core stacking height of the stator core and the rotor core is 70 mm, and the stacking coefficient is 0.97.

[0023] Furthermore, a cooling shell is provided on the outer periphery of the stator, and a cooling medium circulates in the cooling shell; an inner retaining ring is provided on the inner side of the rotor, and a cooling cavity that encloses the stator and the rotor is formed between the inner retaining ring and the cooling shell, and the upper and lower ends of the cooling cavity are sealed by end covers; a cooling medium circulates in the cooling cavity.

[0024] Compared with the prior art, the beneficial effects of the 12000 rpm range extender generator for electric aircraft of the present invention are: by optimizing the design in the main aspects such as motor material selection, magnet arrangement method, skew pole processing method, winding form, etc., it is applied to electric propulsion aircraft; the inner rotor 24 slots, 20 poles, seven-segment rotor core skew slot magnets are radially inserted, and the magnetomotive force waveform is symmetrical, the winding coefficient is high, the torque pulsation and cogging torque are low, and there is no end circulation. The excellent performance; the motor adopts centralized winding, winding oil cooling, and shell water cooling. The power generation voltage is 780V, the current is 350A, the stack height is 70mm, the electromagnetic part weighs 15.34 kg, the motor weighs about 25 kg, the generator power is 266KVA, and the generator power density is as high as 10.6KVA / kg.

Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of a horizontal cross-sectional structure of an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of the structure of the winding in the stator slot in an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of a local structure in an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the longitudinal cross-sectional structure of an embodiment of the present invention;

[0029] Figure 5 This is a magnetomotive force waveform diagram of a motor using a 24-slot 20-pole matching method according to an embodiment of the present invention;

[0030] Figure 6 The winding coefficient distribution histogram of the motor using the 24-slot 20-pole matching mode according to the embodiment of the present invention;

[0031] Figure 7 This is a BH curve diagram of JFE10JNX900 silicon steel sheet (0.1 mm) according to an embodiment of the present invention;

[0032] Figure 8 This is an information diagram of the remanence, coercive force, and square coefficient Hk / Hcj of N52UH magnetic steel in an embodiment of the present invention;

[0033] Fig. 9 Schematic diagram of electromagnetic simulation input conditions under 12000 rpm power in an embodiment of the present invention;

[0034] Fig.10 This is a diagram of electromagnetic simulation data under 12000 rpm power in an embodiment of the present invention;

[0035] Fig.11 This is a cloud diagram of magnetic induction density at 12000 rpm in an embodiment of the present invention;

[0036] Fig.12 This is a diagram of the magnetic induction intensity of each part under 12000 rpm power in an embodiment of the present invention;

[0037] Fig.13 This is a loss distribution diagram obtained by simulation under 12000 rpm power in an embodiment of the present invention;

[0038] Fig.14 This is a torque curve diagram obtained by simulation under 12000 rpm electric power in an embodiment of the present invention;

[0039] Fig.15 This is an efficiency MAP diagram obtained by simulation under 12000 rpm power in an embodiment of the present invention;

[0040] Fig.16 This is a diagram of thermal simulation results at 12000 rpm of electrical power in an embodiment of the present invention;

[0041] Fig.17 A schematic diagram of inputting electromagnetic simulation conditions for minimum starting torque in an embodiment of the present invention;

[0042] Fig.18 This is a simulation result data diagram under the minimum starting torque in an embodiment of the present invention;

[0043] Figure 19-20 This is a simulation diagram of rotor strength in an embodiment of the present invention;

[0044] Fig.21 This is a simulation result diagram of the cogging torque and torque ripple when the 12000 rpm generator is used in an embodiment of the present invention;

[0045] Fig. 22 This is a 2D spectrum of the time-dominant stator radial harmonics of an embodiment of the present invention;

[0046] Fig.23 A Campbell sound pressure field spectrum diagram according to an embodiment of the present invention;

[0047] Fig.24 It is a schematic diagram of stator radial stress data-space 1D of an embodiment of the present invention;

[0048] Fig.25 This is a radial wiring diagram of a stator according to an embodiment of the present invention;

[0049] Figure 26-27 A phase current curve and a generated voltage curve diagram of an embodiment of the present invention;

[0050] Fig.28 An animated diagram of radial stress of a stator according to an embodiment of the present invention;

[0051] The numbers in the figure represent:

[0052] 100-12000 rpm range extender generator for electric aircraft;

[0053] 1- stator, 11- stator core, 111- stator slot, 112- stator tooth, 113- insulating paper, 114- insulating paint, 12- winding; 2- rotor, 21- rotor core, 22- magnetic steel group; 3- cooling shell, 31- cooling channel; 4- inner retaining ring, 41- cooling cavity, 42- end cover. [Specific implementation method]

[0054] Embodiment 1:

[0055] Please refer to Figure 1-Figure 4 The present embodiment is a 12,000-rpm range extender generator 100 for an 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 .

[0056] The stator 1 includes a stator core 11 and a winding 12. The inner wall of the stator core 11 is provided with a plurality of stator slots 111 at equal angles along its own circumference, and each stator slot 111 is provided with a winding 12. A stator tooth 112 is formed between two adjacent stator slots 111. The outer diameter D1 of the stator core 11 is 262 mm, and the inner diameter D2 of the stator core 11 is 202 mm.

[0057] The rotor 2 includes a rotor core 21 and a magnetic steel group 22. The outer wall of the rotor core 21 is provided with a plurality of accommodating cavities (not shown) at equal angles along its own circumference, and each of the accommodating cavities is provided with a group of magnetic steel groups 22. The outer diameter D3 of the rotor core 21 is 198 mm, and the inner diameter D4 of the rotor core 21 is 170 mm.

[0058] The air gap L1 between the stator 1 and the rotor 2 is 2 mm, that is, the distance between the outer wall of the magnetic steel group 22 and the inner wall of the stator core 11. The main cross-sectional shape of the stator slot 111 is rectangular, and a retracted notch is formed on the side close to the inner wall of the stator core 11. The retracted contour is a straight line, and its notch width L2=3 mm, the slot depth L3 of the stator slot 111 is 21 mm, and the inclination angle of the retracted contour, that is, the slot tip angle θ1=30°, the stator slot 111 is a parallel slot, and its parallel slot width L4=15 mm. The pole arc angle θ2=168°, the magnetic steel thickness L5=6 mm. The magnetic steel adopts 52UH neodymium iron boron magnetic steel, with a remanence of 1.46T and a maximum operating temperature of 180°C, and is inserted into the accommodating cavity by radial insertion.

[0059] The more slots there are in the stator slots 111, the lower the harmonic content of the motor will be, which can effectively reduce additional losses, reduce harmonic leakage reactance, and make the magnetic potential waveform closer to a sine wave, which is beneficial to increasing the motor torque. In addition, the total heat dissipation area of ​​the coil side in the slot is increased, which is beneficial to heat dissipation and reduces temperature rise. The number of rotor slots must be designed to match the number of stator slots. If the slots are not properly matched, the motor may fail to start, vibrate and make loud noises, and generate additional losses and additional torque. In this embodiment, the motor uses 24 slots and 20 poles. That is, the number of slots in the stator slots 111 on the stator core 11 is 24. The number of magnetic steel groups 22 on the outer wall of the rotor core 21 is 20 groups, forming 20 poles. Please refer to Figure 5-6 , Figure 5 This is a graph of the height of the magnetomotive force waveform of 24 slots and 20 poles. Figure 6 The histogram of the winding coefficients of 24 slots and 20 poles is shown in Figure 2. Figure 5 It can be seen that the 24-slot 20-pole matching method effectively avoids end circulation heating; Figure 6 It can be seen that the combination of 24 slots and 20 poles has a higher winding coefficient.

[0060] In this embodiment, one pole is composed of 20 magnets. By using 20 segments to process the magnet, the eddy current loss and heat generation of the magnet during motor operation can be effectively reduced. In this embodiment, the magnet is N52UH NdFeB magnet. The remanence, coercive force, and square coefficient Hk / Hcj of N52UH NdFeB magnet are as follows: Figure 8 As shown. Figure 8 It can be seen that N52UH NdFeB magnet can be used for a long time in the range of 180℃, the square coefficient is greater than 0.95, and the remanence Br is 1.46T.

[0061] To ensure sufficient starting torque, the current density cannot be too small, while too large a current density will increase the slip rate, increase rotor resistance loss, reduce efficiency, and increase heat generation. In this embodiment, the winding 12 is wound in the form of a centralized single winding, and is wound with a temperature-resistant grade of 240°C corona-resistant polyimide copper flat wire. The centralized winding is wound with 7 turns per wire. The centralized winding can effectively reduce the end height, thereby reducing the copper loss and heat generation when the motor is running.

[0062] The filling rate of the stator slot 111 is 88.72% (including insulating paper). If the slot filling rate is too large, the winding will not be able to go into the slot; if the slot filling rate is too small, the slot utilization rate is too low, which is not conducive to the heat dissipation of the winding. In this embodiment, the filling rate of the stator slot 111 is designed to be 88.72%, which, combined with the subsequent design of the size of the stator slot 111, not only ensures the feasibility of winding copper flat wire, but also has good heat dissipation performance.

[0063] The insulating paper 113 in the stator slot 111 is DuPont Nomex T410 aramid insulating paper with a thickness of 0.25 mm. The gap between the winding 12 and the stator slot 111 is filled with insulating varnish 114, and the insulating varnish uses VX4201 unsaturated polyester imide resin as the slot filling material.

[0064] The rotor 2 is subjected to a pole tilting treatment, specifically a seven-stage pole tilting treatment, with angles of -1.28571°, -0.857143°, -0.428571°, 0°, 0.428571°, 0.857143°, and 1.28571°. By using a segmented pole tilting treatment with a set angle on the rotor, the torque pulsation and cogging torque of the motor are reduced; the vibration and noise of the motor are also reduced.

[0065] In this embodiment, the stator core 11 and the rotor core 21 are made of 0.1 mm thick JFE10JNX900 silicon steel sheets laminated together, the stator core 11 and the rotor core 21 are laminated together with a core height of 70 mm and a lamination coefficient of 0.97. Figure 7 , Figure 7 The BH curve of JFE10JNX900 silicon steel sheet (0.1mm) reflects the relationship between the magnetic induction intensity and the magnetic field intensity of JFE10JNX900 silicon steel sheet during the magnetization process. It can be seen from the figure that the saturation point is greater than 2.1T (curve not extrapolated).

[0066] A cooling shell 3 is disposed on the outer periphery of the stator 1 . The cooling shell 3 is disposed around the outer periphery of the stator 1 . A cooling channel 31 is formed inside the cooling shell 3 . A cooling medium, such as water, circulates in the cooling channel 31 .

[0067] An inner retaining ring 4 is provided on the inner side of the rotor 2, and a cooling cavity 41 is formed between the inner retaining ring 4 and the cooling shell 3 to enclose the stator 1 and the rotor 2. The upper and lower ends of the cooling cavity 41 are sealed by end covers 42; a cooling medium, such as ATF cooling oil, circulates in the cooling cavity 41.

[0068] In order to verify that the motor designed in this embodiment has excellent performance, a thermal simulation test and an electromagnetic simulation test were performed on the motor, and the tests are as follows:

[0069] (1) Electromagnetic simulation under 12000 rpm forwarding:

[0070] Input conditions for electromagnetic simulation: generating voltage 780V, generating current 350A (rms), maximum motor speed 12000rpm; electromagnetic simulation software is Ansys Motor-CAD, using Maxwell tensor method to simulate the motor electromagnetically, air gap segmentation number is 4 layers, scanning angle is 360°, electromagnetic wire, stator, rotor segmentation length is system default; electromagnetic performance of the motor under generating voltage 780V and generating current 350A is simulated. The lead angle is set to 40°, winding copper wire temperature is set to 175℃, magnetic steel is set to 155℃, shaft temperature is set to 105℃, maximum speed is 12000rpm, iron loss coefficient Ka is 2.2; electrical load, electric density, and thermal load are: 94.576A / mm, 16.69A / mm respectively. 2 , 1578.479A 2 / mm 3 After thermal equilibrium, the highest winding temperature is 146.3℃, the highest temperature is 162.2℃, and the magnetic steel temperature is 67℃. The simulation conditions are input as follows: Fig. 9 shown.

[0071] The electromagnetic simulation results under 12000 rpm are as follows: Fig.10 The simulation results show that the minimum power generation torque is 209.33Nm, the maximum efficiency is 97.57%, and the total loss is 6560W.

[0072] The magnetic induction density cloud diagram under 12000 rpm current is as follows Fig.11 As shown; the magnetic induction intensity of each part is as Fig.12 The simulation results show that the maximum magnetic induction intensity is located at the tooth part, with a maximum of 2.045T, the average magnetic induction intensity of the air gap is 0.6802T, and the maximum magnetic induction intensity of the air gap is 1.181T.

[0073] The loss distribution obtained by simulation under 12000 RT power supply is as follows Fig.13 shown.

[0074] The torque curve obtained by simulation under 12000 rpm is as follows: Fig.14 The simulation results show that the minimum torque required for 12,000 rpm power generation is 209.33 Nm, and the power generation efficiency is 97.57%.

[0075] The efficiency MAP obtained by simulation under 12000 forward power supply is as follows Fig.15 The simulation results of the peak power efficiency MAP show that the motor efficiency is greater than 97% when the speed is between 3000rpm and 12000rpm.

[0076] (2) 12000 forward power supply thermal simulation:

[0077] The inlet temperature of cooling water in cooling shell 3 is 55℃, and the flow rate is 30L / min. The inlet temperature of ATF for spray cooling of winding in cooling cavity 41 is 55℃, and the flow rate is 24L / min. The electric load, electric density and heat load are 94.576A / mm and 16.69A / mm respectively. 2 , 1578.479A 2 / mm 3 After thermal balance, the highest winding temperature is 146.3℃, the highest temperature is 162.2℃, and the magnetic steel temperature is 67℃.

[0078] The thermal simulation results under 12000 forward power are as follows Fig.16 The simulation results show that the thermal equilibrium is achieved within 10 minutes, with the highest temperature of the winding being about 162.2°C and the highest temperature of the magnetic steel being about 67°C, and there is no risk of winding burning or magnetic steel demagnetization.

[0079] (3) Minimum starting torque simulation:

[0080] Simulation condition input: magnet and winding temperature 20℃, current 350A, voltage 780V, leading angle 40°, environment and motor both 20℃.

[0081] The minimum starting torque simulation result data is as follows Fig.18 The results show that the minimum starting torque is 239.33Nm, the cogging torque is 2.1785Nm, and the torque ripple is 2.134%.

[0082] (4) Rotor strength simulation:

[0083] The rotor strength simulation results are as follows: Figure 19-20 The results show that at 12,000 rpm, the rotor is far from reaching the yield point of 425 MPa of JFE10JNX900 material, and the actual maximum stress is only 175 MPa.

[0084] (5)NVH performance test: The simulation results of cogging torque and torque pulsation at 12,000 rpm are as follows: Fig.21 The simulation results show that with the seven-segment rotor skew treatment, the torque ripple is 2.61% and the cogging torque is only 2.85Nm.

[0085] (6) Time-dominated stator radial harmonic 2D spectrum, such as Fig. 22 As shown in the figure, the harmonic 2D spectrum of the radial force on the stator shows that the peaks are round and smooth, which avoids the problem of howling when the motor is running.

[0086] (7) Campbell sound pressure field spectrum, such as Fig.23The results in the figure show that: the spatial order 0 and 4, corresponding to the frequency of about 2300 ~ 3500HZ, has abnormal NVH conditions, and the corresponding speed is above 14000 rpm, the noise is abnormal, and there may be resonance. The motor generating speed is 12000 rpm, avoiding the resonance point.

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

[0088] (9) Stator radial wiring diagram as shown Fig.25 As shown, in this embodiment, the wiring is performed in a manner of two three-phase electric parallel connections.

[0089] (10) The phase current curve and the generation voltage curve are as follows: Fig.26 , 27 As shown in the figure, it can be seen that at 12,000 revolutions, the phase current peak is 494.9A and the generated voltage peak is 780V.

[0090] (11) Stator radial stress animation diagram is as follows Fig.28 shown.

[0091] For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, all of which fall within the protection scope of the present invention.

Claims

1. A 12000 rpm range extender generator for electric aircraft, comprising a stator and a rotor arranged inside the stator; the stator comprises a stator core and a winding, the inner wall of the stator core is provided with a plurality of stator slots at equal angles along its own circumference, and each of the stator slots is provided with the winding; the rotor comprises a rotor core and a magnetic steel group, the outer wall of the rotor core is provided with a plurality of accommodating cavities at equal angles along its own circumference, and each of the accommodating cavities is provided with a group of magnetic steel groups; characterized in that: The number of the stator slots is 24, and the number of the magnetic steel groups is 20, forming a matching structure of 24 slots and 20 poles; The winding adopts concentrated winding; The stator core has an outer diameter D1 of 262 mm and an inner diameter D2 of 202 mm; The outer diameter D3 of the rotor core is 198 mm, and the inner diameter D4 is 170 mm; The air gap between the stator and the rotor is L1=2 mm; The stator slot has a slot width L2=3 mm, a slot depth L3=21 mm, a slot tip angle θ1=30°, and the stator slot is a parallel slot with a parallel slot width L4=15 mm; The rotor adopts seven-stage tilted pole treatment, and the tilted pole treatment angles are: -1.28571°, -0.857143°, -0.428571°, 0°, 0.428571°, 0.857143°, and 1.28571°.

2. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: A stator tooth is formed between two adjacent stator slots, and the air gap is formed between the inner wall of the stator tooth and the outer wall of the magnetic steel group.

3. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The pole arc angle θ2 = 168°.

4. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The magnetic steel in the magnetic steel group has a thickness L5 of 6 mm and is inserted into the accommodating cavity in a radial insertion manner.

5. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The magnetic steel adopts 52UH NdFeB magnetic steel with a remanence of 1.46T and a maximum operating temperature of 180°C.

6. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The group of magnetic steel groups forms a pole, and the pole includes 20 magnetic steels.

7. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The winding is made of corona-resistant polyimide copper flat wire with a temperature resistance grade of 240° C., and a single wire is wound with 7 turns.

8. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The filling rate in the stator slot is 88.72%.

9. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: Insulating paper is provided in the stator slot to isolate the inner wall of the stator slot from the winding; the insulating paper is DuPont Nomex T410 aramid insulating paper with a thickness of 0.25 mm; the gap of the winding in the stator slot is filled with insulating varnish, and the insulating varnish is VX4201 unsaturated polyester imide resin.

10. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: The stator core and the rotor core are formed by laminating JFE10JNX900 silicon steel sheets with a thickness of 0.1 mm. The core stacking height of the stator core and the rotor core is 70 mm, and the lamination coefficient is 0.

97.

11. The 12000 rpm range extender generator for electric aircraft as claimed in claim 1, characterized in that: A cooling shell is arranged on the outer periphery of the stator, and a cooling medium circulates in the cooling shell; an inner retaining ring is arranged on the inner side of the rotor, and a cooling cavity enclosing the stator and the rotor is formed between the inner retaining ring and the cooling shell, and the upper and lower ends of the cooling cavity are sealed by end covers; a cooling medium circulates in the cooling cavity.

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