A 30,000 RPM electric aircraft range extender generator

Abstract

This invention discloses a 30,000 rpm range extender generator for electric aircraft. It adopts an internal rotor with 18 slots, 10 poles, and a five-segment rotor core with radially inserted skewed magnets. It has excellent performance characteristics such as 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, and is 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 range extender generator for electric aircraft with a speed of 30,000 rpm. [Background Technology]

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

[0003] Therefore, it is necessary to provide a new 30,000 rpm 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 30,000 rpm 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 circulation current.

[0005] This invention achieves the above-mentioned objective through the following technical solution: a 30,000 rpm electric aircraft range extender generator, 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 magnet assembly, 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 magnet assemblies; characterized in that:

[0006] The stator has 18 slots and the magnet assembly has 10 units, forming an 18-slot, 10-pole configuration.

[0007] The winding adopts a concentrated winding;

[0008] The stator core has an outer diameter D1 = 262 mm and an inner diameter D2 = 182 mm.

[0009] The outer diameter of the rotor core is D3 = 177 mm and the inner diameter is D4 = 138 mm.

[0010] The air gap L1 between the stator and the rotor is 2.5 mm;

[0011] The stator slot has a slot opening width L2 = 6 mm, a slot depth L3 = 27 mm, a slot tip angle θ1 = 40°, and the stator slot is a parallel slot with a parallel slot width L4 = 11 mm.

[0012] The rotor adopts a five-segment skewed pole treatment, with skewed pole treatment angles of -1.714°, -0.857°, 0°, 0.857°, and 1.714° 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 polar arc angle θ2 = 152°.

[0015] Furthermore, the group of magnets forms a pole, and the pole includes 20 magnets.

[0016] Furthermore, the thickness L5 of the magnet in the magnet assembly is 5.5 mm, and it is 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 winding is made of 240℃ temperature-resistant, corona-resistant polyimide copper flat wire, with 6 turns per wire.

[0019] Furthermore, the stator slot filling rate is 89.06%.

[0020] 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.

[0021] Furthermore, the stator core and the rotor core are made of stacked silicon steel sheets. The stator core is made of 0.1mm thick JFE10JNX900 silicon steel sheets, and the rotor core is made of 0.25mm thick 25WY900 high yield strength silicon steel sheets. The stack height of the stator core and the rotor core is 50mm, and the stacking coefficient is 0.97.

[0022] Furthermore, a cooling shell is provided on the outer periphery of the stator, and a first cooling medium circulates within the cooling shell; 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 shell, which encloses the stator and the rotor; the upper and lower ends of the cooling cavity are sealed by end caps; a second cooling medium circulates within the cooling cavity.

[0023] Furthermore, the rotor is fitted with a protective sleeve to prevent the magnets from flying out. The sleeve is made of carbon fiber and has a thickness of 1.5 mm.

[0024] Compared with existing technologies, the beneficial effects of this invention, a 30,000 rpm electric aircraft range extender generator, 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. It adopts an internal rotor with 18 slots, 10 poles, and a five-segment rotor core with radially inserted skewed magnets, exhibiting excellent performance in terms of symmetrical magnetomotive force waveform, high winding coefficient, low torque pulsation and cogging torque, and no end-circulating current. The motor uses concentrated windings, oil-cooled windings, and water-cooled casing. It generates 762.6V, 400A, with a stack height of 50mm, an electromagnetic component weight of 14.79Kg, a motor weight of approximately 24Kg, a generator power of 305.04KVA, and a generator power density as high as 12.71KVA / kg. [Attached Image Description]

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

[0026] Figure 2 This is a schematic diagram of the structure of the winding in the stator slot in an embodiment of the present invention;

[0027] Figure 3 This is a partial structural diagram in an embodiment of the present invention;

[0028] Figure 4 This 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 an embodiment of the present invention using an 18-slot, 10-pole configuration;

[0030] Figure 6 The BH curve is shown for the 25WY900 high yield strength silicon steel sheet (0.25mm) of this invention.

[0031] Figure 7 The BH curve diagram of JFE10JNX900 silicon steel sheet (0.1mm) in an embodiment of the present invention;

[0032] 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.

[0033] Figure 9 This is a schematic diagram of the electromagnetic simulation input conditions under 30,000 rpm of electrical power in an embodiment of the present invention;

[0034] Figure 10This is an electromagnetic simulation data diagram under 30,000 rpm power in an embodiment of the present invention;

[0035] Figure 11 This is a magnetic induction density cloud map under 30,000 rpm electric power in an embodiment of the present invention;

[0036] Figure 12 This is a diagram showing the magnetic induction intensity of various parts under a 30,000 rpm power output in an embodiment of the present invention.

[0037] Figure 13 This is a loss distribution diagram obtained from simulation at 30,000 rpm in an embodiment of the present invention.

[0038] Figure 14 This is a torque curve obtained from simulation at 30,000 rpm in an embodiment of the present invention.

[0039] Figure 15 This is the efficiency MAP obtained from the simulation at 30,000 rpm in this embodiment of the invention;

[0040] Figure 16 This is a thermal simulation result diagram of 30,000 rpm power in an embodiment of the present invention;

[0041] Figure 17-18 The simulated stress cloud diagram and simulation results of rotor strength in the embodiments of the present invention are shown respectively.

[0042] Figure 19 This is a simulation result diagram of the cogging torque and torque pulsation during 30,000 power reflexes according to Embodiment 3 of the present invention;

[0043] Figure 20 This is a 2D spectrum of the time-dominant stator radial harmonics according to an embodiment of the present invention;

[0044] Figure 21 This is a Campbell sound pressure field spectrum diagram according to an embodiment of the present invention;

[0045] Figure 22 This is a 1D spatial schematic diagram of stator radial stress data according to an embodiment of the present invention.

[0046] Figure 23 This is a stator radial wiring diagram according to an embodiment of the present invention;

[0047] Figure 24-25 The figures shown are the phase current curve and the generator voltage curve of an embodiment of the present invention.

[0048] Figure 26 This is a stator linear wiring diagram according to an embodiment of the present invention;

[0049] The numbers in the diagram represent:

[0050] Electric aircraft range extender generators with speeds of 100-30,000 RPM;

[0051] 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

[0052] Example 1:

[0053] Please refer to Figures 1-4 This embodiment is a 30,000 RPM electric aircraft range extender generator 100, which includes a stator 1, a rotor 2 disposed inside the stator 1, and a heat sink 3 disposed outside the stator 1.

[0054] 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 262 mm, and the inner diameter D2 of the stator core 11 is 182 mm.

[0055] 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 177 mm, and the inner diameter D4 of the rotor core 21 is 138 mm.

[0056] The air gap width L1 between stator 1 and rotor 2 is 2.5mm, 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 = 27mm, and the inclination angle of the inwardly tapered profile, i.e., the slot tip angle θ1 = 40°, are all parallel slots with a parallel slot width L4 = 11mm. The pole arc angle θ2 = 152°, 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℃, and are inserted into the receiving cavity radially.

[0057] 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 18 slots and 10 poles. That is, the number of stator slots 111 on the stator core 11 is 18. The number of magnet groups 22 on the outer wall of the rotor core 21 is 10, forming 10 poles. Figure 5 The diagram shows the height stacking of the magnetomotive force waveform for an 18-slot, 10-pole configuration. This configuration avoids end-circulating currents while maintaining a high winding coefficient.

[0058] In this embodiment, each pole consists of 20 magnets. By segmenting the magnets into 20 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. The remanence, coercivity, and squareness coefficient Hk / Hcj of the N52UH neodymium iron boron magnets are 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.

[0059] In this embodiment, a protective sleeve is provided around the outer periphery of the rotor 2. The sleeve is made of carbon fiber and has a thickness of 1.5mm. During the high-speed rotation of the motor, the carbon fiber sleeve can prevent the magnets from flying out. Moreover, the carbon fiber sleeve has ultra-high strength and rigidity, which can provide excellent protection for the rotor 2 without increasing the weight of the motor, thus achieving a lightweight design. The carbon fiber sleeve has high thermal conductivity, which can dissipate heat quickly and avoid overheating. At the same time, the carbon fiber sleeve has a low coefficient of thermal expansion and will not deform due to temperature changes, ensuring the stable performance of the motor in various working environments.

[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 89.06% (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 89.06%, 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 filling material for the stator slot 111.

[0063] Rotor 2 is skewed, specifically using a five-segment skew design with angles of -1.714°, -0.857°, 0°, 0.857°, and 1.714°. By employing segmented skewed design with set angles on the rotor, the motor's torque ripple and cogging torque are reduced, as are its vibration and noise.

[0064] In this embodiment, the stator core 11 and the rotor core 21 are formed by stacking silicon steel sheets. The stator core 11 uses 0.1mm thick JFE10JNX900 silicon steel sheets, and the rotor core 21 uses 0.25mm thick 25WY900 high-yield-strength silicon steel sheets. The stack height of the stator core 11 and rotor core 21 is 50mm, and the stacking factor is 0.97. Please refer to... Figures 6-7 , Figure 6 The BH curve of 25WY900 high yield strength silicon steel sheet (0.25mm) 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 1.95T. Figure 7 The BH curve of JFE10JNX900 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 first cooling medium, such as cooling water, circulates in the cooling channel 31. Other first cooling media can also be used according to actual conditions, and there is no restriction here.

[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 second cooling medium, such as ATF cooling oil, circulates in the cooling cavity 41. Other second cooling media can also be used according to actual conditions, which are not limited here.

[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 30,000 rpm:

[0069] Electromagnetic simulation input conditions: Generating voltage 762.6V, generating current 400A (rms), maximum motor speed 30000rpm; the electromagnetic simulation software used was Ansys Motor-CAD, employing Maxwell's tensor method for electromagnetic simulation of the motor. The air gap was divided into 5 layers, the scanning angle was 360°, and the electromagnetic wire, stator, and rotor section lengths were set to system defaults. The electromagnetic performance of the motor under a generating voltage of 762.6V and a generating current of 400A was simulated. The lead angle was set to 40°, the winding copper wire temperature was set to 175℃, the magnet temperature was set to 155℃, the shaft temperature was set to 105℃, the maximum speed was 30000rpm, and the iron loss coefficient Ka was set to 2.2; the electrical load, electrical density, and thermal load were 77.73A / mm, 18.02A / mm, and respectively. 2 1400.67A 2 / mm 3 After thermal equilibrium, the highest winding temperature is 180℃, and the magnet temperature is 78℃. Simulation conditions input are as follows: Figure 9 As shown.

[0070] Electromagnetic simulation results at 30,000 rpm are as follows: Figure 10 As shown in the figure, the simulation results show that the minimum generating torque is 108.01 Nm, the maximum efficiency is 97.745%, and the total loss is 6601.5 W.

[0071] The magnetic induction density cloud map under 30,000 rpm is shown below. Figure 11 As shown, the magnetic induction intensity of each part is as follows Figure 12 As shown, the simulation results show that the maximum magnetic induction intensity is located at the tooth part, with a maximum of 1.778T, the average magnetic induction intensity in the air gap is 0.6219T, and the maximum magnetic induction intensity in the air gap is 1.453T.

[0072] The loss distribution obtained from the simulation at 30,000 rpm is as follows: Figure 13 As shown.

[0073] The torque curve obtained from the simulation at 30,000 rpm is as follows: Figure 14 As shown in the simulation results, a minimum torque of 91.07 Nm is required when generating 30,000 volts, and the power generation efficiency is 97.745%.

[0074] The efficiency MAP obtained from the simulation at 30,000 rpm is shown below. Figure 15 As shown in the figure, the simulation results of the efficiency MAP at peak power show that the motor efficiency is greater than 97% in the speed range of 7000rpm to 30000rpm.

[0075] (2) 30,000 rpm electrical thermal simulation:

[0076] The cooling water inlet temperature in the cooling shell 3 is 55℃, and the water flow rate is 30L / min. The ATF oil inlet temperature for spraying cooling to the windings in the cooling cavity 41 is 65℃, and the ATF oil flow rate is 24L / min. The electrical load, electrical density, and thermal load are 77.73A / mm, 18.02A / mm, and 18.02A / mm, respectively. 2 1400.67A 2 / mm 3 After thermal equilibrium is reached, the highest temperature of the winding is 180℃, and the magnet temperature is 78℃.

[0077] The results of the 30,000 rpm electric thermal simulation are as follows: Figure 16 As shown, the simulation results indicate that the highest winding temperature under steady-state conditions is 180℃, the magnet temperature is 78℃, the carbon fiber sheath temperature of rotor 2 is 91℃, the casing temperature is approximately 71℃, and the temperature of the stator core 11 teeth is approximately 150℃.

[0078] (3) Rotor strength simulation:

[0079] The rotor strength simulation results are as follows Figure 17-18 As shown, Figure 17 Stress cloud diagram for rotor strength simulation. Figure 18 The simulation results for rotor strength show that at 30,000 rpm, the rotor is far from reaching the yield point of 950 MPa for 25WY900 material, and the actual maximum stress is only 721 MPa.

[0080] (4) NVH performance test: Simulation results of cogging torque and torque pulsation at 30,000 rpm are as follows Figure 19 As shown, the simulation results show that with the five-segment rotor skewed pole treatment, the torque pulsation is 2.242% and the cogging torque is only 0.034 Nm.

[0081] (5) Time-dominant stator radial harmonic 2D spectrum, such as Figure 20 As shown, the 2D harmonic spectrum of the stator radial force shows that the peaks are rounded and smooth, avoiding the problem of whistling during motor operation.

[0082] (6) Campbell's sound pressure field spectrum, such as Figure 21As shown in the figure, the results indicate that there are NVH abnormalities at spatial orders -8, -2, 4, and 10, corresponding to frequencies of approximately 3800 to 6300 Hz. The corresponding noise abnormalities are above 45,000 rpm, which may indicate resonance. The motor generating speed is 30,000 rpm (corresponding to 2500 Hz), thus avoiding the resonance point.

[0083] (7) Stator radial stress data, such as Figure 22 As shown.

[0084] (8) Stator radial wiring diagram as follows Figure 23 As shown, in this embodiment, the wiring adopts a two-way three-phase power parallel connection method.

[0085] (9) The phase current curve and the generation voltage curve are respectively as shown in Figure 1. Figure 24 , 25 As shown in the figure, the peak phase current at 30,000 revolutions per minute is 565.6A and the peak generation voltage is 762.6V.

[0086] (10) Stator linear connection diagram as follows Figure 26 As shown.

[0087] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A 30,000 rpm 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 magnet assembly, 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 magnet assemblies; characterized in that: The stator has 18 slots and the magnet assembly has 10 units, forming an 18-slot, 10-pole configuration. The windings are concentrated windings; The stator core has an outer diameter D1 = 262 mm and an inner diameter D2 = 182 mm. The outer diameter of the rotor core is D3 = 177 mm and the inner diameter is D4 = 138 mm. The air gap L1 between the stator and the rotor is 2.5 mm; The stator slot has a slot opening width L2 = 6 mm, a slot depth L3 = 27 mm, a slot tip angle θ1 = 40°, and the stator slot is a parallel slot with a parallel slot width L4 = 11 mm. The rotor adopts a five-segment skewed pole treatment, with skewed pole treatment angles of -1.714°, -0.857°, 0°, 0.857°, and 1.714° respectively.

2. The 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: 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 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: The polar arc angle θ2 = 152°.

4. The 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: The group of magnets forms a pole, and the pole includes 20 magnets.

5. The 30,000 rpm range extender generator for electric aircraft as described in claim 4, characterized in that: The thickness of the magnet in the magnet assembly is L5 = 5.5 mm, and it is inserted into the receiving cavity in a radial insertion manner.

6. The 30,000 rpm range extender generator for electric aircraft as described in claim 4, characterized in that: The magnet is made of 52UH neodymium iron boron magnet with a remanence of 1.46T and a maximum operating temperature of 180℃.

7. The 30,000 rpm 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 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: The stator slot filling rate is 89.06%.

9. The 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: 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 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: The stator core and the rotor core are made of stacked silicon steel sheets. The stator core is made of 0.1mm thick JFE10JNX900 silicon steel sheets, and the rotor core is made of 0.25mm thick 25WY900 high yield strength silicon steel sheets. The stack height of the stator core and the rotor core is 50mm, and the stacking coefficient is 0.

97.

11. The 30,000 rpm range extender generator for electric aircraft as described in claim 1, characterized in that: A cooling shell is provided on the outer periphery of the stator, and a first cooling medium circulates within the cooling shell; 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 shell, which encloses the stator and the rotor; the upper and lower ends of the cooling cavity are sealed by end caps; a second cooling medium circulates within the cooling cavity.

12. The 30,000 rpm range extender generator for electric aircraft as described in claim 4, characterized in that: The rotor is fitted with a protective sleeve to prevent the magnets from flying out. The sleeve is made of carbon fiber and has a thickness of 1.5 mm.

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