Range extender generator for electric aircraft

Abstract

The invention discloses a range extender generator for an electric aircraft, which adopts the mode of 36 slots and 28 poles of an inner rotor and three sections of rotor iron core skewed slot magnetic steel radial insertion, and has the performance 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 range extender generator for an 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 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 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 range extender generator for an 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 36, and the number of the magnetic steel groups is 28, forming a matching structure of 36 slots and 28 poles;

[0007] The winding adopts concentrated winding;

[0008] The stator core has an outer diameter D1=290 mm and an inner diameter D2=243 mm;

[0009] The outer diameter D3 of the rotor core is 240 mm, and the inner diameter D4 is 216 mm;

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

[0011] The slot width L2 of the stator slot is 4.5 mm, the slot depth L3 is 17.7 mm, the slot tip angle θ1 is 25°, and the stator slot is a parallel slot with a parallel slot width L4 of 13 mm;

[0012] The rotor adopts three-stage pole tilting treatment, and the pole tilting treatment angles are: -1.66667°, 0°, and 1.66667° respectively.

[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 = 160°.

[0016] Furthermore, the thickness of the magnetic steel in the magnetic steel group is L5=5.5 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 10 magnetic steels.

[0019] Furthermore, 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.

[0020] Furthermore, the filling rate of the stator slots is 88.55%.

[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 Baosteel B0AV1000 silicon steel sheets with a thickness of 0.5 mm, the core stacking height of the stator core and the rotor core is 33 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.

[0024] Furthermore, an inner retaining ring is provided 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.

[0025] Compared with the prior art, the beneficial effects of the 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, pole skew processing method, winding form, etc., it is applied to electric propulsion aircraft; it adopts the radial insertion method of inner rotor, 36 slots, 28 poles, and three-section rotor core skew slot magnets, and has the performance of symmetrical magnetomotive force waveform, high winding coefficient, low torque pulsation and cogging torque, and no end circulation; the motor adopts centralized winding, winding oil cooling, and shell water cooling. The power generation voltage is 770V, the current is 150A, the stack height is 33mm, the electromagnetic part weighs 7.13 kg, the motor weighs about 12 kg, the generator power density is as high as 9.625KVA / kg, and the power factor is as high as 0.9213.

Brief Description of the Drawings

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

[0027] Figure 2 Schematic diagram of the structure of the winding in the stator slot in an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of a local structure in an embodiment of the present invention;

[0029] Figure 4 It 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 matching method according to an embodiment of the present invention;

[0031] Figure 6 The winding coefficient distribution histogram of the motor using the 36-slot 28-pole matching mode according to the embodiment of the present invention;

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

[0033] 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;

[0034] Fig. 9 This is an electromagnetic simulation data diagram under 7000 rpm power in an embodiment of the present invention;

[0035] Fig.10 This is a cloud diagram of magnetic induction density at 7000 rpm in an embodiment of the present invention;

[0036] Fig.11 This is a diagram of the magnetic induction intensity of each part under a power of 7000 rpm in an embodiment of the present invention;

[0037] Fig.12 This is a loss distribution diagram obtained by simulation under 7000 rpm power in an embodiment of the present invention;

[0038] Fig.13 This is a torque curve diagram obtained by simulation under 7000 rpm electric power in an embodiment of the present invention;

[0039] Fig.14 This is an efficiency MAP diagram obtained by simulation under 7000 rpm power in an embodiment of the present invention;

[0040] Fig.15 This is a diagram of thermal simulation results at 7000 rpm of electrical power in an embodiment of the present invention;

[0041] Fig.16 This is a simulation data diagram under the minimum starting torque in an embodiment of the present invention;

[0042] Fig.17 Magnetic induction density cloud diagram under maximum torque in an embodiment of the present invention;

[0043] Fig.18 : is a magnetic induction intensity diagram of each part under maximum torque in an embodiment of the present invention;

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

[0045] Fig.21 This is a simulation result diagram of the cogging torque and torque ripple when the 7000 rpm generator is turned on in the embodiment of the present invention;

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

[0047] Fig.23 A Campbell sound pressure field spectrum diagram according to an embodiment of the present invention;

[0048] Fig.24 This is a diagram of radial stress data of a stator according to an embodiment of the present invention;

[0049] Figure 25-26 A phase current curve and a generated voltage curve diagram of an embodiment of the present invention;

[0050] The numbers in the figure represent:

[0051] 100-range extender generator for electric aircraft;

[0052] 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]

[0053] Embodiment 1:

[0054] Please refer to Figure 1-Figure 4 The present embodiment is a 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.

[0055] 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 290 mm, and the inner diameter D2 of the stator core 11 is 243 mm.

[0056] 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 240 mm, and the inner diameter D4 of the rotor core 21 is 216 mm.

[0057] The air gap L1 between the stator 1 and the rotor 2 is 1.5 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=4.5 mm, the slot depth L3 of the stator slot 111 is 17.7 mm, and the inclination angle of the retracted contour, that is, the slot tip angle θ1=25°, the stator slot 111 is a parallel slot, and its parallel slot width L4=13 mm. The pole arc angle θ2=160°, the magnetic steel thickness L5=5.5 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.

[0058] 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 36 slots and 28 poles. That is, the number of slots in the stator slots 111 on the stator core 11 is 36. The number of magnetic steel groups 22 on the outer wall of the rotor core 21 is 28 groups, forming 28 poles. Please refer to Figure 5-6 , Figure 5 This is a graph of the height of the magnetomotive force waveform of 36 slots and 28 poles. Figure 6 The histogram of winding coefficients for 36 slots and 28 poles is shown in Figure 2. Figure 5 It can be seen that the 36-slot 28-pole matching method effectively avoids end circulation heating; Figure 6 It can be seen that the combination of 36 slots and 28 poles has a higher winding coefficient.

[0059] In this embodiment, one pole is composed of 10 magnets. By using 10-segment processing of 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.

[0060] 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 1 wire and 7 turns. The centralized winding can effectively reduce the end height, thereby reducing the copper loss and heat generation when the motor is running.

[0061] The filling rate of the stator slot 111 is 88.55% (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 88.55%, 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.

[0062] 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.

[0063] The rotor 2 is subjected to a pole tilting treatment, specifically a three-stage pole tilting treatment, with angles of -1.66667°, 0°, and 1.66667°. By adopting 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 reduced.

[0064] In this embodiment, the stator core 11 and the rotor core 21 are laminated with 0.1 mm thick Baosteel B0AV1000 silicon steel sheets. The stacking height of the stator core 11 and the rotor core 21 is 33 mm, and the stacking coefficient is 0.97. Figure 7 , Figure 7 The BH curve of B10AV1000 silicon steel sheet (0.1mm) reflects the relationship between the magnetic induction intensity and the magnetic field intensity of the B10AV1000 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).

[0065] 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 circulates in the cooling channel 31 .

[0066] 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 circulates in the cooling cavity 41.

[0067] 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:

[0068] (1) Electromagnetic simulation under 7000 rpm forwarding:

[0069] Electromagnetic simulation input conditions: current input 150A, voltage input 770V, lead angle set to 40°, winding copper wire temperature set to 155℃, magnetic steel set to 125℃, shaft temperature set to 95℃, maximum speed 7000rpm, iron loss coefficient Ka is 1.7; electrical load, electrical density, thermal equivalent: 100.32A / mm, 19.7A / mm2, 1976.27A2 / mm3.

[0070] The electromagnetic simulation results under 7000 rpm are as follows: Fig. 9The simulation results show that the power generation torque is 166.24Nm, the maximum efficiency is 96.49%, and the total loss is 4320.3W.

[0071] The magnetic induction density cloud diagram under 7000 rpm is as follows Fig.10 As shown; the magnetic induction intensity of each part is as Fig.11 The simulation results show that the maximum magnetic induction intensity is located at the tooth part, with a maximum of 1.935T, the average magnetic induction intensity of the air gap is 0.7662T, and the maximum magnetic induction intensity of the air gap is 1.297T.

[0072] The loss distribution obtained by simulation under 7000 RT power supply is as follows Fig.12 shown.

[0073] The torque curve obtained by simulation under 7000 rpm is as follows: Fig.13 The simulation results show that the minimum torque required for 7000 rpm power generation is 166.24 Nm, and the power generation efficiency is 96.59%.

[0074] The efficiency MAP obtained by simulation under 7000 rpm power supply is as follows: Fig.14 The simulation results of the peak power efficiency MAP show that the motor efficiency is greater than 96% when the speed is between 2000rpm and 7000rpm.

[0075] (2) 7000-transfer power supply thermal simulation:

[0076] Thermal simulation input conditions: cooling water inlet temperature 30 °C, cooling ATF oil inlet temperature 65 °C, water flow rate 30 liters per minute, ATF oil flow rate 18 liters per minute.

[0077] The thermal simulation results under 7000 forward power supply are as follows Fig.15 The simulation results show that within 10 minutes of thermal equilibrium, the winding temperature is up to 174.1°C and the magnetic steel temperature is about 69.3°C, with no risk of winding burnout or magnetic steel demagnetization.

[0078] (3) Minimum starting torque simulation:

[0079] Simulation condition input: magnet and winding temperature 20℃, current 150A, voltage 770V, leading angle 40°.

[0080] The minimum starting torque simulation result data is as follows Fig.16 The results show that the minimum starting torque is 189.45Nm, the cogging torque is 3.7798Nm, and the torque ripple is 1.1927%.

[0081] The magnetic induction density cloud diagram at maximum torque is as follows Fig.17 As shown, the magnetic induction intensity of each part is Fig.18The simulation results show that at startup, the highest magnetic induction intensity is 1.942T, the maximum air gap magnetic flux density is 1.368T, and the average is 0.8268T.

[0082] (4) Rotor strength simulation:

[0083] The rotor strength simulation results are as follows: Figure 19-20 The results show that at 7000rpm, the rotor is far from reaching the yield point of 452 MPa of the B10AV1000 material, and the actual maximum stress is less than 100 MPa.

[0084] (5)NVH performance test: The simulation results of cogging torque and torque ripple at 7000 rpm are as follows: Fig.21 The simulation results show that with the three-stage rotor skew treatment, the torque ripple is less than 1.5% and the cogging torque is only 0.51362Nm.

[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.23 The results in the figure show that: the 6th and 12th spatial orders, corresponding to the frequency of 3200-4800HZ, have abnormal NVH conditions, corresponding to the speed of more than 16000 rpm (7000rpm, 36 slots, 28 poles corresponding to 1400HZ).

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

[0088] (9) The phase current curve and the generation voltage curve are as follows: Fig.25 , 26 As shown in the figure, it can be seen that at 7000 revolutions, the phase current peak is 212.1A and the generated voltage peak is 789.7V.

[0089] 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 range extender generator for an 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 36, and the number of the magnetic steel groups is 28, forming a matching structure of 36 slots and 28 poles; The winding adopts concentrated winding; The stator core has an outer diameter D1=290 mm and an inner diameter D2=243 mm; The outer diameter D3 of the rotor core is 240 mm, and the inner diameter D4 is 216 mm; The air gap L1 between the stator and the rotor is 1.5 mm; The slot width L2 of the stator slot is 4.5 mm, the slot depth L3 is 17.7 mm, the slot tip angle θ1 is 25°, and the stator slot is a parallel slot with a parallel slot width L4 of 13 mm; The rotor adopts three-stage pole tilting treatment, and the pole tilting treatment angles are: -1.66667°, 0°, and 1.66667° respectively.

2. The range extender generator for electric aircraft according to 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 range extender generator for electric aircraft according to claim 1, characterized in that: The pole arc angle θ2 = 160°.

4. The range extender generator for electric aircraft according to claim 1, characterized in that: The magnetic steel in the magnetic steel group has a thickness L5 of 5.5 mm and is inserted into the accommodating cavity in a radial insertion manner.

5. The range extender generator for electric aircraft according to 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 range extender generator for electric aircraft according to claim 1, characterized in that: The group of magnetic steel groups forms a pole, and the pole includes 10 magnetic steels.

7. The range extender generator for electric aircraft according to 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 range extender generator for electric aircraft according to claim 1, characterized in that: The filling rate of the stator slot is 88.55%.

9. The range extender generator for electric aircraft according to 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 range extender generator for electric aircraft according to claim 1, characterized in that: The stator core and the rotor core are formed by stacking Baosteel B0AV1000 silicon steel sheets with a thickness of 0.5 mm. The core stacking height of the stator core and the rotor core is 33 mm, and the stacking coefficient is 0.

97.

11. The range extender generator for electric aircraft according to claim 1, characterized in that: A cooling shell is disposed on the outer periphery of the stator, and a cooling medium circulates in the cooling shell.

12. The range extender generator for electric aircraft according to claim 11, characterized in that: 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. 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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