Electric machine system for aircraft

Abstract

This electric machine system for an aircraft comprises: a first electric machine which is provided to a gas turbine engine; a second electric machine which is provided to the gas turbine engine; a first conversion circuit which performs conversion between alternating current and direct current; a second conversion circuit which performs conversion between alternating current and direct current; first wiring which is capable of electrically connecting the first conversion circuit to the first electric machine in order to use the first conversion circuit in the first electric machine; second wiring which is capable of electrically connecting the second conversion circuit to the second electric machine in order to use the second conversion circuit in the second electric machine; and third wiring which is capable of electrically connecting the first conversion circuit to the second electric machine in order to use the first conversion circuit in the second electric machine.

Description

Aircraft Electromechanical Systems

[0001] The present disclosure relates to electromechanical systems for aircraft equipped with gas turbine engines.

[0002] Patent Document 1 discloses a configuration in which two power generation systems are provided in a two-shaft gas turbine engine for an aircraft. A first power generation system is connected to the high-pressure shaft of the two-shaft gas turbine engine, and a second power generation system is connected to the low-pressure shaft of the two-shaft gas turbine engine. The first power generation system includes a first generator driven by the high-pressure shaft and a first rectifier device connected to the first generator and converting alternating current to direct current. The second power generation system includes a second generator driven by the low-pressure shaft and a second rectifier device connected to the second generator and converting alternating current to direct current.

[0003] JP 2014-131469 A

[0004] In the configuration of Patent Document 1, if one of the two rectifier devices fails, one of the two generators will lose its power generation function, resulting in a decrease in the overall amount of power generated. Furthermore, if the generator functions as a motor, the motor function will be lost due to the failure of the rectifier device.

[0005] SUMMARY OF THE INVENTION Accordingly, one aspect of the present disclosure aims to increase redundancy in electromechanical systems provided in gas turbine engines of aircraft.

[0006] An electric machine system for an aircraft according to one aspect of the present disclosure includes a first electric machine provided in a gas turbine engine, a second electric machine provided in the gas turbine engine, a first conversion circuit that converts between alternating current and direct current, a second conversion circuit that converts between alternating current and direct current, first wiring that can electrically connect the first conversion circuit to the first electric machine to use the first conversion circuit with the first electric machine, second wiring that can electrically connect the second conversion circuit to the second electric machine to use the second conversion circuit with the second electric machine, and third wiring that can electrically connect the first conversion circuit to the second electric machine to use the first conversion circuit with the second electric machine.

[0007] According to one aspect of the present disclosure, the performance of the electromechanical system can be maintained even when the second conversion circuit fails, thereby increasing the redundancy of the electromechanical system provided in the gas turbine engine of an aircraft.

[0008] Fig. 1 is a cross-sectional view of a gas turbine engine for an aircraft according to an embodiment. Fig. 2 is a block diagram of an electromechanical system provided in the gas turbine engine of Fig. 1. Fig. 3 is a timing chart of the operation of the electromechanical system of Fig. 2, including engine start. Fig. 4 is a timing chart of the operation of the electromechanical system of Fig. 2, including first assist drive. Fig. 5 is a timing chart of the operation of the electromechanical system of Fig. 2, including second assist drive. Fig. 6 is a table showing connection destinations of the remaining conversion circuits of the electromechanical system of Fig. 2 when a failure occurs in at least one of the conversion circuits.

[0009] Hereinafter, an embodiment will be described with reference to the drawings.

[0010] 1 is a cross-sectional view of an aircraft gas turbine engine 1 according to an embodiment. In the following description, "forward" means the upstream side in the direction of airflow within the engine, and "aft" means the downstream side in the direction of airflow within the engine.

[0011] As shown in FIG. 1 , the gas turbine engine 1 includes a rotating shaft 2, a fan 3, a compressor 4, a combustor 5, a turbine 6, a casing 7, and a nose cone 8. The rotating shaft 2 extends in the front-to-rear direction of the gas turbine engine 1. The fan 3 is connected to the front of the rotating shaft 2 and rotates together with the rotating shaft 2. The compressor 4, the combustor 5, and the turbine 6 are aligned in this order from front to rear along the rotating shaft 2. The casing 7 is a cylindrical object with an axis coinciding with the rotational axis of the rotating shaft 2, and houses the rotating shaft 2, the fan 3, the compressor 4, the combustor 5, and the turbine 6. The nose cone 8 is disposed on the rotational axis of the rotating shaft 2 and in front of the fan 3. The outer circumferential surface of the nose cone 8 has a generally conical shape whose diameter decreases toward the front, and guides air from the front to the fan 3. The interior of the nose cone 8 is hollow.

[0012] The gas turbine engine 1 is a two-shaft gas turbine engine. The rotating shaft 2 includes a low-pressure shaft 11 and a high-pressure shaft 12 that is arranged coaxially with the low-pressure shaft 11 and is rotatable relative to the low-pressure shaft 11. The high-pressure shaft 12 has a cylindrical shape. The low-pressure shaft 11 is inserted into a hollow space in the high-pressure shaft 12. The low-pressure shaft 11 is longer in the front-to-rear direction than the high-pressure shaft 12. The front and rear portions of the low-pressure shaft 11 are exposed to the outside of the high-pressure shaft 12. The low-pressure shaft 11 is connected to a fan 3.

[0013] The compressor 4 includes a low-pressure compressor 13 and a high-pressure compressor 14 arranged behind the low-pressure compressor 13. For example, the low-pressure compressor 13 is an axial compressor, and the high-pressure compressor 14 is a centrifugal compressor. However, the types of the low-pressure compressor 13 and the high-pressure compressor 14 are not limited to this. The turbine 6 includes a low-pressure turbine 15 and a high-pressure turbine 16 arranged in front of the low-pressure turbine 15. The low-pressure shaft 11 mechanically connects the low-pressure compressor 13 to the low-pressure turbine 15. The high-pressure shaft 12 mechanically connects the high-pressure compressor 14 to the high-pressure turbine 16.

[0014] The casing 7 includes an inner shell 17 and an outer shell 18. The inner shell 17 has a substantially cylindrical shape and houses the compressor 4, the combustor 5, and the turbine 6. The outer shell 18 also has a substantially cylindrical shape and is arranged concentrically with the inner shell 17 while being spaced radially outward from the inner shell 17. A cylindrical bypass passage B is formed between the inner shell 17 and the outer shell 18. A portion of the air sucked in by the fan 3 flows through the bypass passage B and is discharged rearward.

[0015] A generator 21 is disposed in the internal space of the nose cone 8. The rotor of the generator 21 is mechanically connected to the low-pressure shaft 11. The generator 21 is driven by the rotational force of the low-pressure shaft 11 to generate electricity. The rotational axis of the generator 21 coincides with the rotational axis of the rotating shaft 2.

[0016] A cylindrical body 19 is arranged between the low-pressure compressor 13, which is an axial flow compressor, and the high-pressure compressor 14, which is a centrifugal compressor, to define, from the inner circumferential side, a flow path for compressed air flowing from the low-pressure compressor 13 to the high-pressure compressor 14. The diameter of the cylindrical body 19 decreases from the low-pressure compressor 13 toward the high-pressure compressor 14. A motor-generator 22 is arranged inside the cylindrical body 19. The motor-generator 22 is arranged between the low-pressure compressor 13 and the high-pressure compressor 14 in the front-rear direction. The rotor of the motor-generator 22 is mechanically connected to the high-pressure shaft 12.

[0017] The motor generator 22 functions as a starter motor that transmits the driving force to the high-voltage shaft 12. The motor generator 22 also functions as a generator that generates electricity when driven by the rotational force of the high-voltage shaft 12. The rotational axis of the motor generator 22 coincides with the rotational axis of the rotating shaft 2. The generator 21 and the motor generator 22 are electrically connected to wiring that extends toward the outside of the outer shell 18 of the casing 7.

[0018] An electric accessory 25 used for operating the gas turbine engine 1 is provided on the outer peripheral surface of the outer shell 18 of the casing 7. The electric accessory 25 is, for example, an electric fuel pump including a fuel pump 24 and an electric motor 23. The fuel pump 24 delivers fuel from a fuel tank toward the combustor 5. The fuel pump 24 is driven by the electric motor 23. The accessory driven by the electric motor 23 is not limited to the fuel pump 24, and may be any accessory that requires an input of driving force. For example, the accessory driven by the electric motor 23 may be a lubricating oil pump.

[0019] Fig. 2 is a block diagram of an electromechanical system 30 provided in the gas turbine engine 1 of Fig. 1. As shown in Fig. 2, the electromechanical system 30 includes a generator 21, a motor-generator 22, an electric motor 23, a first conversion device 31, a second conversion device 32, a third conversion device 33, a control device 34, a battery 35, a rotational speed sensor 36, a first irreversible demagnetization determiner 37, a second irreversible demagnetization determiner 38, and the like.

[0020] The generator 21 is an example of a first electric machine mechanically connected to the low-pressure shaft 11 (see FIG. 1 ). The motor generator 22 is an example of a second electric machine mechanically connected to the high-pressure shaft 12 (see FIG. 1 ). The electric motor 23 is a fuel pump motor mechanically connected to the electric motor 23 (see FIG. 1 ) and is an example of an electric machine that constitutes the electric accessory 25.

[0021] The generator 21 has a permanent magnet 21 a provided on the rotor and a coil 21 b provided on the stator. The motor generator 22 has a permanent magnet 22 a provided on the rotor and a coil 22 b provided on the stator. The electric motor 23 has a permanent magnet 23 a provided on the rotor and a coil 23 b provided on the stator.

[0022] The current capacity of the generator 21 when generating power is greater than the current capacity of the motor generator 22 when generating power. The current capacity of the motor generator 22 when driving is greater than the current capacity of the electric motor 23 when driving. The size of the generator 21 is greater than the size of the motor generator 22. The size of the motor generator 22 is greater than the size of the electric motor 23.

[0023] The first conversion device 31 includes a first conversion circuit 41. The second conversion device 32 includes a second conversion circuit 42. The third conversion device 33 includes a third conversion circuit 43. The electromechanical system 30 includes first to sixth wirings 51 to 56 that electrically connect the first to third conversion circuits 41 to 43 to any of the generator 21, the motor generator 22, and the electric motor 23, respectively.

[0024] The first wiring 51 electrically connects the first conversion circuit 41 to the coil 21b of the generator 21 to transmit the electric power generated by the generator 21 to the first conversion circuit 41. The first wiring 51 is provided with a switch 61 that can interrupt the electrical connection between the first conversion circuit 41 and the generator 21.

[0025] The second wiring 52 electrically connects the second conversion circuit 42 to the coil 22b of the motor generator 22 in order to send the electric power generated by the motor generator 22 to the second conversion circuit 42 and to supply the electric power from the second conversion circuit 42 to the motor generator 22. The second wiring 52 is provided with a switch 62 that can interrupt the electrical connection between the second conversion circuit 42 and the motor generator 22.

[0026] The third wiring 53 electrically connects the first conversion circuit 41 to the coil 22b of the motor generator 22 in order to supply power from the first conversion circuit 41 to the motor generator 22 and to send power generated by the motor generator 22 to the first conversion circuit 41. The third wiring 53 is provided with a switch 63 that can interrupt the electrical connection between the first conversion circuit 41 and the motor generator 22.

[0027] The fourth wiring 54 electrically connects the third conversion circuit 43 to the coil 23b of the electric motor 23 to supply power from the third conversion circuit 43 to the electric motor 23. The fourth wiring 54 is provided with a switch 64 that can interrupt the electrical connection between the third conversion circuit 43 and the electric motor 23.

[0028] The fifth wiring 55 electrically connects the first conversion circuit 41 to the coil 23b of the electric motor 23 to supply power from the first conversion circuit 41 to the electric motor 23. The fifth wiring 55 is provided with a switch 65 that can interrupt the electrical connection between the first conversion circuit 41 and the electric motor 23.

[0029] The sixth wiring 56 electrically connects the second conversion circuit 42 to the coil 23b of the electric motor 23 to supply power from the second conversion circuit 42 to the electric motor 23. The sixth wiring 56 is provided with a switch 66 that can interrupt the electrical connection between the second conversion circuit 42 and the electric motor 23.

[0030] In the electromechanical system 30, there is no wiring that can electrically connect the second conversion circuit 42 to the generator 21 to send the electric power generated by the generator 21 to the second conversion circuit 42, and there is no wiring that can electrically connect the third conversion circuit 43 to the generator 21 to send the electric power generated by the generator 21 to the third conversion circuit 43. In other words, there is a first wiring 51 that connects the generator 21 to the first conversion circuit 41, but there is no wiring that connects the generator 21 to the second conversion circuit 42 or the third conversion circuit 43. This prevents an increase in weight of the aircraft on which the electromechanical system 30 is installed.

[0031] The first conversion circuit 41 converts AC supplied from the generator 21 or the motor generator 22 via the first wiring 51 or the third wiring 53 into DC and charges the battery 35. The first conversion circuit 41 converts DC supplied from the battery 35 into AC and supplies it to the motor generator 22 or the electric motor 23 via the third wiring 53 or the fifth wiring 55.

[0032] The second conversion circuit 42 converts the AC supplied from the motor-generator 22 via the second wiring 52 into DC and charges the battery 35. The second conversion circuit 42 converts the DC supplied from the battery 35 into AC and supplies it to the motor-generator 22 or the electric motor 23 via the second wiring 52 or the sixth wiring 56. The current capacity of the second conversion circuit 42 is smaller than the current capacity of the first conversion circuit 41. The size of the second conversion device 32 is smaller than the size of the first conversion device 31. The motor-generator 22 connected to the high-voltage shaft 12 (see FIG. 1 ) and the corresponding second conversion circuit 42 are miniaturized, which contributes to the miniaturization of the aircraft.

[0033] The third conversion circuit 43 converts the direct current supplied from the battery 35 into alternating current and supplies it to the electric motor 23 via the fourth wiring 54. The current capacity of the third conversion circuit 43 is smaller than the current capacity of the second conversion circuit 42.

[0034] The control device 34 includes a control circuit 44. The control circuit 44 includes a processor, a system memory, a storage memory, etc. The processor may include a CPU. The system memory may include a RAM. The storage memory may include a ROM. The storage memory may include a hard disk, a flash memory, or a combination thereof. The storage memory stores a program. A configuration in which the processor executes a program read into the system memory is one example of the control circuit 44.

[0035] The control circuit 44 is electrically connected to the first conversion circuit 41, the second conversion circuit 42, and the third conversion circuit 43. The control circuit 44 controls the first conversion circuit 41, the second conversion circuit 42, and the third conversion circuit 43. The control circuit 44 also controls the opening and closing of the switches 61 to 66.

[0036] A rotational speed sensor 36 is electrically connected to the control circuit 44. The rotational speed sensor 36 detects the rotational speed of the rotating shaft 2. In this embodiment, the rotational speed sensor 36 detects the rotational speed of the high-pressure shaft 12 (see FIG. 1 ). Note that if the control circuit 44 is configured to calculate the rotational speed of the motor-generator 22 by detecting the frequency of the AC from the motor-generator 22, the rotational speed of the motor-generator 22 can be considered to be the rotational speed of the high-pressure shaft 12, and therefore the rotational speed sensor 36 may be omitted. Alternatively, the rotational speed sensor 36 may detect the rotational speed of the low-pressure shaft 11.

[0037] The first irreversible demagnetization determiner 37 includes a first irreversible demagnetization determination circuit 47. The first irreversible demagnetization determination circuit 47 is electrically connected to the motor-generator 22. The first irreversible demagnetization determination circuit 47 determines whether irreversible demagnetization has occurred in the permanent magnet 22a of the motor-generator 22. For example, the first irreversible demagnetization determination circuit 47 measures at least one of the current value and the voltage value during rotation of the motor-generator 22 and determines irreversible demagnetization by comparing the measured current value with a normal value when no irreversible demagnetization has occurred under the same conditions. For example, the first irreversible demagnetization determination circuit 47 determines that irreversible demagnetization has occurred when it determines that the currently measured value has decreased from the normal value by more than a predetermined amount under the same conditions.

[0038] The second irreversible demagnetization determiner 38 includes a second irreversible demagnetization determination circuit 48. The second irreversible demagnetization determination circuit 48 is electrically connected to the electric motor 23. The second irreversible demagnetization determination circuit 48 determines whether irreversible demagnetization has occurred in the permanent magnet 23a of the electric motor 23. For example, similar to the first irreversible demagnetization determination circuit 47, the second irreversible demagnetization determination circuit 48 measures at least one of the current value and the voltage value during rotation of the electric motor 23 and determines irreversible demagnetization by comparing the measured value with a normal value when no irreversible demagnetization has occurred under the same conditions.

[0039] FIG. 3 is a timing chart of the operation, including engine start, of the electromechanical system 30 of FIG. 2 . The operation of the electromechanical system 30 will be described below primarily with reference to FIG. 3 , with appropriate reference to FIGS. 1 and 2 . When the gas turbine engine 1 is stopped, the switches 61 to 66 are open. When the control circuit 44 receives a start command requesting the start of the engine 1, the control circuit 44 closes the switch 63 provided on the third wiring 53 and controls the first conversion circuit 41 to convert DC from the battery 35 to AC in the first conversion circuit 41. The AC converted from DC in the first conversion circuit 41 is supplied to the motor-generator 22 via the third wiring 53, and the high-voltage shaft 12 is driven by the motor-generator 22. The power source used to drive the motor-generator 22 when starting the engine 1 is not limited to the battery 35, and an external battery or external power source may be used.

[0040] That is, the first conversion circuit 41 is used instead of the second conversion circuit 42 to drive the motor-generator 22 when starting the engine 1. Because the current capacity of the first conversion circuit 41 is larger than the current capacity of the second conversion circuit 42, a large current is supplied from the first conversion circuit 41 to the motor-generator 22, causing a large torque to be generated in the motor-generator 22, and the engine 1 starts smoothly.

[0041] The control circuit 44 generates an ignition command when it determines that the rotational speed detected by the rotational speed sensor 36 has reached the threshold value N1 (N1>0). That is, the control circuit 44 closes the switch 64 and controls the third conversion circuit 43 to convert the direct current from the battery 35 to alternating current, which is then supplied to the electric motor 23 via the fourth wiring 54. With the electric motor 23 driven and fuel being supplied from the fuel pump 24 to the combustor 5, the control circuit 44 causes the combustor 5 to perform an ignition operation.

[0042] When the control circuit 44 determines that the starting of the engine 1 is complete, it opens the switch 63 and controls the first conversion circuit 41 to stop the supply of power from the first conversion circuit 41 to the motor generator 22. For example, the control circuit 44 may determine that the starting of the engine 1 is complete when it determines that the rotational speed detected by the rotational speed sensor 36 has reached a threshold value N2 (N2>N1). Alternatively, the control circuit 44 may determine that the starting of the engine 1 is complete when it determines that the rotational speed detected by the rotational speed sensor 36 has suddenly increased due to ignition and exceeded the threshold value.

[0043] After the engine 1 has started, the first conversion circuit 41 and the second conversion circuit 42 do not energize the generator 21, the motor generator 22, or the electric motor 23 until the rotational speed detected by the rotational speed sensor 36 reaches a threshold value N4 (N4>N2). The control circuit 44 generates a switching command during the period from when the engine 1 has started until the rotational speed detected by the rotational speed sensor 36 reaches the threshold value N4. For example, the control circuit 44 generates the switching command when it determines that the rotational speed detected by the rotational speed sensor 36 has reached a threshold value N3 (N2<N3<N4).

[0044] In response to the switching command, the control circuit 44 switches the connection of the first conversion circuit 41 to the generator 21 and switches the connection of the second conversion circuit 42 to the motor-generator 22. That is, the control circuit 44 closes the switches 61 and 62 while keeping the switch 63 open. In this way, the electrical connections of the first conversion circuit 41 and the second conversion circuit 42 are switched while the first conversion circuit 41 and the second conversion circuit 42 do not energize any of the generator 21, the motor-generator 22, and the electric motor 23, thereby achieving a stable switching operation.

[0045] When the control circuit 44 determines that the rotation speed detected by the rotation speed sensor 36 has reached the threshold N4, it causes the generator 21 driven by the low-voltage shaft 11 to generate electricity and causes the first conversion circuit 41 to convert the AC generated by the generator 21 to DC. When the control circuit 44 determines that the rotation speed detected by the rotation speed sensor 36 has reached the threshold N4, it causes the motor generator 22 driven by the high-voltage shaft 12 to generate electricity and causes the second conversion circuit 42 to convert the AC generated by the motor generator 22 to DC. The DC converted from AC by the first conversion circuit 41 and the second conversion circuit 42 charges the battery 35.

[0046] Although the threshold value N4 that causes the generator 21 to start generating power and the threshold value N4 that causes the motor generator 22 to start generating power are the same in the above embodiment, they may be different from each other. The rotational speed compared with the threshold values ​​N1 to N4 may be the rotational speed of the high-pressure shaft 12 detected by the rotational speed sensor 36, or may be a value obtained by correcting the rotational speed of the high-pressure shaft 12 or the low-pressure shaft 11 detected by the rotational speed sensor.

[0047] Figure 4 is a timing chart of the operation, including the first assist drive, of the electromechanical system 30 of Figure 2. Below, the operation of the electromechanical system 30 will be described mainly with reference to Figure 4, while also referring to Figures 1 and 2 as appropriate. When an assist start command is generated while the gas turbine engine 1 is in operation, the control circuit 44 causes the first conversion circuit 41 to supply power from the battery 35 to the motor-generator 22 so that the engine 1 is assisted by the driving force of the motor-generator 22. Figure 4 describes an example in which the assist start command is generated when the rotational speed detected by the rotational speed sensor 36 decreases while the gas turbine engine 1 is in operation.

[0048] Specifically, when the control circuit 44 determines that the rotational speed detected by the rotational speed sensor 36 is equal to or greater than the threshold value N13, it causes the generator 21 driven by the low-voltage shaft 11 to generate electricity and causes the first conversion circuit 41 to convert the AC generated by the generator 21 to DC. Furthermore, when the control circuit 44 determines that the rotational speed detected by the rotational speed sensor 36 is equal to or greater than the threshold value N13, it causes the motor-generator 22 driven by the high-voltage shaft 12 to generate electricity and causes the second conversion circuit 42 to convert the AC generated by the motor-generator 22 to DC. The control circuit 44 closes switches 61, 62, and 64 and opens switches 63, 65, and 66. The DC converted from AC by the first conversion circuit 41 and the second conversion circuit 42 is charged to the battery 35. Note that the threshold value N13 may be the same as or different from the threshold value N4 in FIG. 3 . While the threshold value N13 that causes the generator 21 to start generating electricity and the threshold value N13 that causes the motor-generator 22 to start generating electricity are the same in the above embodiment, they may be different from each other.

[0049] The control circuit 44 generates an assist start command when it determines that the rotational speed detected by the rotational speed sensor 36 has decreased and reached the threshold value N11. That is, the assist start command is automatically generated by the control circuit 44. When the assist start command is generated, the control circuit 44 controls the first conversion circuit 41 to convert DC from the battery 35 to AC in the first conversion circuit 41. The AC converted from DC in the first conversion circuit 41 is supplied to the motor-generator 22 via the third wiring 53, and the high-voltage shaft 12 is driven by the motor-generator 22. When the assist start command is generated, the control circuit 44 performs a switching operation to open switches 61 and 62 and then close switch 63. That is, the first conversion circuit 41 is used instead of the second conversion circuit 42 to drive the motor-generator 22 during assisted driving of the engine 1.

[0050] The control circuit 44 generates an assist end command when it determines that the rotational speed detected by the rotational speed sensor 36 has increased and reached the threshold value N12. That is, the assist end command is automatically generated by the control circuit 44. When the assist end command is generated, the control circuit 44 controls the first conversion circuit 41 to stop the supply of power from the first conversion circuit 41 to the motor generator 22. The processing circuit 44 may open the switch 63 when the assist end command is generated, or may open the switch 63 when the rotational speed detected by the rotational speed sensor 36 reaches any rotational speed in the interval between the threshold value N12 and the threshold value N14.

[0051] At least one of the assist start command and the assist end command may be generated in response to a manual operation by a human, regardless of the rotational speed detected by rotational speed sensor 36. The rotational speed compared with threshold values ​​N1, N11 to N13 may be the rotational speed of high-pressure shaft 12 detected by rotational speed sensor 36, but may also be a value obtained by correcting the rotational speed of high-pressure shaft 12 or low-pressure shaft 11 detected by the rotational speed sensor.

[0052] Fig. 5 is a timing chart of the operation including the second assist drive of the electromechanical system of Fig. 2. Hereinafter, the operation of the electromechanical system 30 will be described mainly with reference to Fig. 5 while also referring to Figs. 1 and 2 as appropriate. In the example of Fig. 5, the threshold N15 at which the assist start command is issued is greater than the threshold N14 at which the generator 21 starts generating power.

[0053] Specifically, when the control circuit 44 determines that the rotation speed detected by the rotation speed sensor 36 has increased and reached the threshold value N14, it causes the generator 21 driven by the low-voltage shaft 11 to generate electricity and causes the first conversion circuit 41 to convert the AC generated by the generator 21 to DC. The control circuit 44 closes switches 61 and 64 and opens switches 62, 63, 65, and 66. The DC converted from the AC by the first conversion circuit 41 charges the battery 35.

[0054] When control circuit 44 determines that the rotational speed detected by rotational speed sensor 36 has increased and reached threshold value N15, it generates an assist start command. When the assist start command is generated, control circuit 44 controls first conversion circuit 41 to convert the direct current from battery 35 to alternating current in first conversion circuit 41, and the alternating current converted from the direct current in first conversion circuit 41 is supplied to motor generator 22 via third wiring 53, and motor generator 22 drives high-voltage shaft 12. When the assist start command is generated, control circuit 44 performs a switch switching operation to open switches 61 and 62 and then switch 63.

[0055] When the control circuit 44 determines that the rotational speed detected by the rotational speed sensor 36 has increased and reached the threshold value N16, it generates an assist end command. When the assist end command is generated, the control circuit 44 controls the first conversion circuit 41 to stop the power supply from the first conversion circuit 41 to the motor generator 22, then causes the generator 21 driven by the low-voltage shaft 11 to generate power, causes the first conversion circuit 41 to convert the AC generated by the generator 21 to DC, and also causes the motor generator 22 driven by the high-voltage shaft 12 to generate power, and causes the second conversion circuit 42 to convert the AC generated by the motor generator 22 to DC. When the assist end command is generated, the processing circuit 44 opens the switch 63 and then closes the switches 61 and 62.

[0056] 3. The threshold value N16 that causes the generator 21 to start generating power and the threshold value N16 that causes the motor generator 22 to start generating power are the same, but they may be different. The rotational speed compared with the threshold values ​​N1, N14 to N16 may be the rotational speed of the high-pressure shaft 12 detected by the rotational speed sensor 36, or may be a value obtained by correcting the rotational speed of the high-pressure shaft 12 or the low-pressure shaft 11 detected by the rotational speed sensor.

[0057] Fig. 6 is a table showing the connection destinations of the remaining conversion circuits when a failure occurs in at least one of the conversion circuits 41 to 43 of the electromechanical system 30 in Fig. 2. In Fig. 6, LP_GEN refers to the generator 21 for the low-pressure shaft 11, HP_M / GEN refers to the motor-generator 22 for the high-pressure shaft 12, and Fuel_M refers to the electric motor 23 for the fuel pump 24, i.e., the fuel pump motor. Below, the operation of the electromechanical system 30 in the event of a failure will be described based on Fig. 6, with appropriate reference to Fig. 2. It is assumed that the failure occurs under conditions where the generator 21 and the motor-generator 22 are generating electricity and the electric motor 23 is driving the fuel pump 24.

[0058] Case 1 in Figure 6 illustrates a case where the third conversion circuit 43 fails. When the control circuit 44 detects a failure of the third conversion circuit 43, it connects the first conversion circuit 41 to the generator 21 for the low-pressure shaft 11 and the second conversion circuit 42 to the electric motor 23 for the fuel pump 24. As a result, although the power generation function of the motor-generator 22 for the high-pressure shaft 12 is lost, the fuel pump 24 can be operated to maintain operation of the gas turbine engine 1. In this case, power is generated by the generator 21, which has a larger current capacity than the motor-generator 22, so a significant decrease in the amount of power generation can be suppressed. Note that, when the control circuit 44 detects a failure of the third conversion circuit 43, it is also possible to connect the second conversion circuit 42 to the motor-generator 22 for the high-pressure shaft 12 and the first conversion circuit 41 to the electric motor 23 for the fuel pump 24.

[0059] 6 shows a case where a failure occurs in the second conversion circuit 42. When the control circuit 44 detects a failure in the second conversion circuit 42, it connects the first conversion circuit 41 to the generator 21 for the low-pressure shaft 11, and connects the third conversion circuit 43 to the electric motor 23 for the fuel pump 24. As a result, although the power generation function of the motor generator 22 for the high-pressure shaft 12 is lost, the fuel pump 24 can be operated to maintain operation of the gas turbine engine 1.

[0060] 6 , when the control circuit 44 detects a failure of the generator 21 in addition to a failure of the second conversion circuit 42, the first conversion circuit 41 may be connected to the motor-generator 22 for the high-pressure shaft 12. In this way, even if the power generating function of the generator 21 for the low-pressure shaft 11 is lost, the motor-generator 22 for the high-pressure shaft 12 can generate power. Therefore, while the first conversion circuit 41 is normally used for the generator 21 and the second conversion circuit 42 is normally used for the motor-generator 22, when the second conversion circuit 42 fails, the first conversion circuit 41 can be used for the motor-generator 22.

[0061] 6 shows a case where a failure occurs in the first conversion circuit 41. When the control circuit 44 detects a failure in the first conversion circuit 41, it connects the second conversion circuit 42 to the motor-generator 22 for the high-pressure shaft 12, and connects the third conversion circuit 43 to the electric motor 23 for the fuel pump 24. As a result, although the power generating function of the generator 21 for the low-pressure shaft 11 is lost, it is possible to operate the fuel pump 24 and maintain operation of the gas turbine engine 1.

[0062] 6 shows a case where the second conversion circuit 42 and the third conversion circuit 43 fail. When the control circuit 44 detects the failure of the second conversion circuit 42 and the third conversion circuit 43, it connects the first conversion circuit 41 to the electric motor 23 for the fuel pump 24. As a result, although the power generation function of the generator 21 and the motor generator 22 is lost, the fuel pump 24 can be operated to maintain operation of the gas turbine engine 1.

[0063] 6 shows a case where the first conversion circuit 41 and the third conversion circuit 43 fail. When the control circuit 44 detects the failure of the first conversion circuit 41 and the third conversion circuit 43, it connects the second conversion circuit 42 to the electric motor 23 for the fuel pump 24. As a result, although the power generation functions of the generator 21 and the motor-generator 22 are lost, the fuel pump 24 can be operated to maintain operation of the gas turbine engine 1.

[0064] 2, when the first irreversible demagnetization determination circuit 47 determines that irreversible demagnetization has occurred in the permanent magnet 22a of the motor generator 22, the control circuit 44 controls the first conversion circuit 41 to supply power from the first conversion circuit 41 to the coil 22b of the motor generator 22 to remagnetize the permanent magnet 22a. Since the permanent magnet 22a of the motor generator 22 is remagnetized using the first conversion circuit 41, which has a larger current capacity than the second conversion circuit 42 for the motor generator 22, the magnetizing effect is enhanced by the larger current.

[0065] When the second irreversible demagnetization determination circuit 48 determines that irreversible demagnetization has occurred in the permanent magnet 23 a of the electric motor 23, the control circuit 44 controls the first conversion circuit 41 or the second conversion circuit 42 to supply power from the first conversion circuit 41 or the second conversion circuit 42 to the coil 23 b of the electric motor 23 to remagnetize the permanent magnet 23 a. Since the permanent magnet 23 a of the electric motor 23 is remagnetized using the first conversion circuit 41 or the second conversion circuit 42, which has a larger current capacity than the third conversion circuit 43 for the electric motor 23 of the electric accessory 25, the magnetizing effect is enhanced by the larger current. In this case, it is preferable to remagnetize the permanent magnet 23 a of the electric motor 23 using the first conversion circuit 41, which has a larger current capacity than the second conversion circuit 42, because the magnetizing effect is sufficiently enhanced by the sufficiently large current.

[0066] The gas turbine engine 1 may be a single-shaft gas turbine engine. A second conversion circuit 42 may be used to drive the motor-generator 22 when starting the engine 1. The motor-generator 22 may be a generator that does not function as a starter motor. The starter of the gas turbine engine 1 may be an APU (Auxiliary Power Unit) or a GPU (Ground Power Unit). The switches 61 to 66 may be omitted.

[0067] The generator 21 may be disposed at a location other than inside the nose cone 8. For example, a configuration may be adopted in which rotational power is transmitted from the low-pressure shaft 11 to the generator 21 disposed outside the outer shell 18 via a power transmission mechanism. The motor generator 22 may be disposed at a location other than inside the cylindrical body 19. For example, a configuration may be adopted in which rotational power is transmitted from the high-pressure shaft 12 to the motor generator 22 disposed outside the outer shell 18 via a power transmission mechanism.

[0068] At least one of the fifth wiring 55 and the sixth wiring 56 may be omitted. The group of the third conversion device 33 and the electric motor 23 may be unrelated to at least one of the group of the first conversion device 31 and the generator 21 and the group of the second conversion device 32 and the motor-generator 22. The fuel pump 24 does not have to be electrically driven.

[0069] Either the group of the first conversion device 31 and the generator 21 or the group of the second conversion device 32 and the motor-generator 22 may be omitted. A configuration may also be adopted in which the motor-generator 22 corresponds to the first electric machine, the second conversion device 32 corresponds to the first conversion device, the electric motor 23 of the electric accessory 25 corresponds to the second electric machine, and the third conversion device 33 corresponds to the second conversion device. A configuration may also be adopted in which the generator 21 corresponds to the first electric machine, the first conversion device 31 corresponds to the first conversion device, the electric motor 23 corresponds to the second electric machine, and the third conversion device 33 corresponds to the second conversion device.

[0070] As described above, the above embodiments have been described as examples of the technology disclosed in this application. However, the technology of the present disclosure is not limited to these and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Furthermore, the components described in the above embodiments can be combined to create new embodiments. For example, some configurations or methods in one embodiment may be applied to other embodiments, and some configurations in an embodiment can be separated and arbitrarily extracted from other configurations in that embodiment. Furthermore, the components described in the accompanying drawings and detailed description include not only components essential for solving the problem, but also components that are not essential for solving the problem, and are used to illustrate the technology.

[0071] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), graphics processing units (GPUs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. Processors are considered processing circuits or circuits because they include transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0072] [Aspects] The above-described embodiments are specific examples of the following aspects.

[0073] (Aspect 1) An electric machine system for an aircraft comprising: a first electric machine provided in a gas turbine engine; a second electric machine provided in the gas turbine engine; a first conversion circuit that converts between alternating current and direct current; a second conversion circuit that converts between alternating current and direct current; first wiring that can electrically connect the first conversion circuit to a first electric machine to use the first conversion circuit with the first electric machine; second wiring that can electrically connect the second conversion circuit to a second electric machine to use the second conversion circuit with the second electric machine; and third wiring that can electrically connect the first conversion circuit to the second electric machine to use the first conversion circuit with the second electric machine.

[0074] According to the above configuration, while the first conversion circuit is used for the first electric machine and the second conversion circuit is used for the second electric machine, if a failure occurs in the second conversion circuit, the first conversion circuit can be used for the second electric machine. Therefore, even if a failure occurs in the second conversion circuit, the performance of the electric mechanical system can be maintained, and the redundancy of the electric mechanical system provided in the gas turbine engine of an aircraft can be improved.

[0075] (Aspect 2) The electromechanical system of an aircraft according to aspect 1, wherein the system does not include wiring capable of electrically connecting the second conversion circuit to the first electric machine so that the first electric machine uses the second conversion circuit.

[0076] According to the above configuration, system redundancy is increased by the second wiring capable of connecting the first conversion circuit to the second electric machine, while weight increase can be suppressed by not providing wiring capable of connecting the second conversion circuit to the first electric machine.

[0077] (Aspect 3) The aircraft electric machine system according to aspect 1 or 2, wherein the first electric machine and the second electric machine are mechanically connected to a rotating shaft of the gas turbine engine.

[0078] According to the above configuration, it is possible to improve the redundancy of the electric machine mechanically connected to the rotating shaft of the engine.

[0079] (Aspect 4) The electric mechanical system of an aircraft according to aspect 3, wherein the gas turbine engine is a two-shaft gas turbine engine, the rotating shaft includes a high-pressure shaft and a low-pressure shaft, the first electric machine is mechanically connected to the low-pressure shaft, and the second electric machine is mechanically connected to the high-pressure shaft.

[0080] According to the above configuration, it is possible to increase the redundancy of the electromechanical system provided in the two-shaft gas turbine engine of an aircraft.

[0081] (Aspect 5) The aircraft electromechanical system according to Aspect 4, wherein the first electric machine and the second electric machine function as at least generators, the power generation capacity of the second electric machine is smaller than the power generation capacity of the first electric machine, and the current capacity of the second conversion circuit is smaller than the current capacity of the first conversion circuit.

[0082] According to the above configuration, the second electric machine connected to the high voltage shaft and the second conversion circuit corresponding to the second electric machine can be made smaller, which contributes to making the aircraft smaller.

[0083] (Aspect 6) An aircraft electric mechanical system as described in Aspect 5, further comprising a control circuit electrically connected to the first conversion circuit and the second conversion circuit, wherein the second electric machine is a motor-generator, and the control circuit is configured to control the first conversion circuit to supply electric power from the first conversion circuit to the second electric machine when a start command requesting start of the gas turbine engine is generated, in order to cause the second electric machine to drive the high pressure shaft.

[0084] According to the above configuration, the second conversion circuit for the second electric machine can be made smaller, while at the time of engine start, a large current can be supplied to the second electric machine from the first conversion circuit instead of the second conversion circuit, thereby enabling the second electric machine to generate the large torque required for engine start.

[0085] (Aspect 7) The electromechanical system for an aircraft according to aspect 6, wherein the control circuit is configured to: generate an ignition command to ignite the gas turbine engine when the rotational speed of the rotating shaft increases and reaches a threshold value after issuance of the start command; control the first conversion circuit to stop the supply of power from the first conversion circuit to the second electric machine when it is determined that the start of the gas turbine engine is completed after issuance of the ignition command; switch the connection of the first conversion circuit from the second electric machine to the first electric machine when the start of the gas turbine engine is completed and the power supply is stopped; and after switching the connection of the first conversion circuit from the second electric machine to the first electric machine, cause the first conversion circuit to convert AC generated by the first electric machine to DC, and cause the second conversion circuit to convert AC generated by the second electric machine to DC.

[0086] According to the above configuration, the electrical connection destination of the first conversion circuit is switched in a state where the power supply from the first conversion circuit to the second electric machine is stopped, so that a stable switching operation can be achieved.

[0087] (Aspect 8) An aircraft electric mechanical system according to any of Aspects 5 to 7, further comprising a control circuit electrically connected to the first conversion circuit and the second conversion circuit, wherein the second electric machine is a motor-generator, and the control circuit is configured to control the first conversion circuit to supply electric power from the first conversion circuit to the second electric machine to drive the high pressure shaft when an assist start command requesting assistance in driving the gas turbine engine is generated.

[0088] According to the above configuration, the second conversion circuit for the second electric machine can be made smaller, and when the engine is assisted by the second electric machine, a large current can be supplied to the second electric machine from the first conversion circuit instead of the second conversion circuit, thereby enabling the second electric machine to generate the large torque required for the engine.

[0089] (Aspect 9) The electromechanical system of an aircraft according to any one of Aspects 1 to 8, further comprising: an electric accessory used to operate the gas turbine engine; a third conversion circuit that converts between alternating current and direct current; a fourth wiring that can electrically connect the third conversion circuit to the electric accessory to use the third conversion circuit with the electric accessory; a fifth wiring that can electrically connect the first conversion circuit to the electric accessory to use the first conversion circuit with the electric accessory; and a sixth wiring that can electrically connect the second conversion circuit to the electric accessory to use the second conversion circuit with the electric accessory.

[0090] According to the above configuration, when the third conversion circuit fails, the first conversion circuit or the second conversion circuit can be used for the electric accessories, so that the operation of the engine can be maintained even if the third conversion circuit for the electric accessories necessary for the operation of the engine fails.

[0091] (Aspect 10) An electromechanical system for an aircraft described in any one of Aspects 1 to 9, wherein the second electric machine includes a generator having a permanent magnet and a coil, the current capacity of the first conversion circuit is greater than the current capacity of the second conversion circuit, the electromechanical system further includes: a control circuit electrically connected to the first conversion circuit and the second conversion circuit; and an irreversible demagnetization determination circuit that determines whether irreversible demagnetization has occurred in the permanent magnet, and the control circuit is configured to control the first conversion circuit to supply power from the first conversion circuit to the coil when the irreversible demagnetization determination circuit determines that irreversible demagnetization has occurred in the permanent magnet.

[0092] According to the above configuration, the permanent magnet of the second electric machine is remagnetized using the first conversion circuit, which has a larger current capacity than the second conversion circuit for the second electric machine, so that the magnetization effect can be enhanced by the large current.

[0093] (Aspect 11) The electric accessory includes an accessory and an electric motor having a permanent magnet and a coil and driving the accessory, wherein a current capacity of at least one of the first conversion circuit and the second conversion circuit is greater than a current capacity of the third conversion circuit, and the electromechanical system further includes: a control circuit electrically connected to the first conversion circuit, the second conversion circuit, and the third conversion circuit; and an irreversible demagnetization determination circuit that determines whether irreversible demagnetization has occurred in the permanent magnet, and the control circuit is configured to control the at least one conversion circuit to supply power from the at least one conversion circuit to the coil when the irreversible demagnetization determination circuit determines that irreversible demagnetization has occurred in the permanent magnet.

[0094] According to the above configuration, the permanent magnet of the electric accessory is re-magnetized using a conversion circuit having a larger current capacity than the third conversion circuit for the electric accessory, so that the magnetizing effect can be enhanced by the large current.

[0095] (Aspect 12) The electromechanical system of an aircraft according to aspect 11, wherein a current capacity of the first conversion circuit is greater than a current capacity of the second conversion circuit, and the control circuit is configured to control the first conversion circuit to supply power from the first conversion circuit to the coil when the irreversible demagnetization determination circuit determines that irreversible demagnetization has occurred in the permanent magnet.

[0096] According to the above configuration, the permanent magnet of the electric accessory is re-magnetized using the first conversion circuit, which has a larger current capacity than the second conversion circuit, so that the magnetizing effect can be sufficiently enhanced by the large current.

[0097] (Aspect 13) The aircraft electric mechanical system according to Aspect 1 or 2, wherein the first electric machine is a generator mechanically connected to a rotating shaft of the gas turbine engine, and the second electric machine is an electric motor of an electric accessory used to operate the gas turbine engine.

[0098] According to the above configuration, it is possible to improve the redundancy of the electric accessories used to operate the engine.

[0099] REFERENCE SIGNS LIST 1 Gas turbine engine 2 Rotating shaft 11 Low pressure shaft 12 High pressure shaft 21 Generator; first electric machine 22 Motor generator; second electric machine or first electric machine 22a Permanent magnet 22b Coil 23 Electric motor; third electric machine or second electric machine 23a Permanent magnet 23b Coil 24 Fuel pump 25 Electric accessory 30 Electromechanical system 41 First conversion circuit 42 Second conversion circuit 43 Third conversion circuit 44 Control circuit 47 First irreversible demagnetization determination circuit 48 Second irreversible demagnetization determination circuit 51 First wiring 52 Second wiring 53 Third wiring 54 Fourth wiring 55 Fifth wiring 56 Sixth wiring 61 to 66 Switches

Claims

1. An electromechanical system for an aircraft comprising: a first electric machine provided in a gas turbine engine; a second electric machine provided in the gas turbine engine; a first conversion circuit that converts between AC and DC; a second conversion circuit that converts between AC and DC; first wiring that can electrically connect the first conversion circuit to the first electric machine to use the first conversion circuit with the first electric machine; second wiring that can electrically connect the second conversion circuit to the second electric machine to use the second conversion circuit with the second electric machine; and third wiring that can electrically connect the first conversion circuit to the second electric machine to use the first conversion circuit with the second electric machine.

2. An aircraft electromechanical system according to claim 1, which does not include wiring capable of electrically connecting said second conversion circuit to said first electric machine in order to use said second conversion circuit with said first electric machine.

3. An aircraft electromechanical system according to claim 1 or 2, wherein the first electric machine and the second electric machine are mechanically connected to a rotating shaft of the gas turbine engine.

4. An aircraft electromechanical system according to claim 3, wherein the gas turbine engine is a two-shaft gas turbine engine, the rotating shafts include a high-pressure shaft and a low-pressure shaft, the first electric machine is mechanically connected to the low-pressure shaft, and the second electric machine is mechanically connected to the high-pressure shaft.

5. An aircraft electromechanical system according to claim 4, wherein the first electric machine and the second electric machine function as at least generators, the power generation capacity of the second electric machine is smaller than the power generation capacity of the first electric machine, and the current capacity of the second conversion circuit is smaller than the current capacity of the first conversion circuit.

6. An electromechanical system for an aircraft as set forth in claim 5, further comprising a control circuit electrically connected to said first conversion circuit and said second conversion circuit, said second electric machine being a motor-generator, and said control circuit being configured to control said first conversion circuit to supply electric power from said first conversion circuit to said second electric machine in order to cause said second electric machine to drive said high pressure shaft when a start command requesting start of said gas turbine engine is generated.

7. The electromechanical system of claim 6, wherein the control circuit is configured to: generate an ignition command to ignite the gas turbine engine when the rotational speed of the rotating shaft increases and reaches a threshold value after issuance of the start command; control the first conversion circuit to stop the supply of power from the first conversion circuit to the second electric machine when it is determined that the start of the gas turbine engine has been completed after the issuance of the ignition command; switch the connection of the first conversion circuit from the second electric machine to the first electric machine when the start of the gas turbine engine has been completed and the power supply has been stopped; and after switching the connection of the first conversion circuit from the second electric machine to the first electric machine, cause the first conversion circuit to convert the AC generated by the first electric machine to DC, and cause the second conversion circuit to convert the AC generated by the second electric machine to DC.

8. An aircraft electromechanical system according to any one of claims 5 to 7, further comprising a control circuit electrically connected to the first conversion circuit and the second conversion circuit, wherein the second electric machine is a motor-generator, and the control circuit is configured to control the first conversion circuit to supply electric power from the first conversion circuit to the second electric machine in order to cause the second electric machine to drive the high pressure shaft when an assist start command requesting assistance in driving the gas turbine engine is generated.

9. An electromechanical system for an aircraft according to any one of claims 1 to 8, further comprising: an electric accessory used in operation of the gas turbine engine; a third conversion circuit that converts between AC and DC; a fourth wiring that can electrically connect the third conversion circuit to the electric accessory so that the third conversion circuit is used with the electric accessory; a fifth wiring that can electrically connect the first conversion circuit to the electric accessory so that the first conversion circuit is used with the electric accessory; and a sixth wiring that can electrically connect the second conversion circuit to the electric accessory so that the second conversion circuit is used with the electric accessory.

10. An electromechanical system for an aircraft according to any one of claims 1 to 9, wherein the second electric machine includes a generator having a permanent magnet and a coil, the current capacity of the first conversion circuit is greater than the current capacity of the second conversion circuit, and the electromechanical system further comprises: a control circuit electrically connected to the first conversion circuit and the second conversion circuit; and an irreversible demagnetization determination circuit that determines whether irreversible demagnetization has occurred in the permanent magnet, and the control circuit is configured to control the first conversion circuit to supply power from the first conversion circuit to the coil when the irreversible demagnetization determination circuit determines that irreversible demagnetization has occurred in the permanent magnet.

11. An electromechanical system for an aircraft as set forth in claim 9, wherein the electric accessory includes an accessory and an electric motor having a permanent magnet and a coil and driving the accessory, wherein the current capacity of at least one of the first conversion circuit and the second conversion circuit is greater than the current capacity of the third conversion circuit, and the electromechanical system further includes: a control circuit electrically connected to the first conversion circuit, the second conversion circuit, and the third conversion circuit; and an irreversible demagnetization determination circuit that determines whether irreversible demagnetization has occurred in the permanent magnet, and the control circuit is configured to control the at least one conversion circuit to supply power from the at least one conversion circuit to the coil when the irreversible demagnetization determination circuit determines that irreversible demagnetization has occurred in the permanent magnet.

12. An electromechanical system for an aircraft as described in claim 11, wherein the current capacity of the first conversion circuit is greater than the current capacity of the second conversion circuit, and the control circuit is configured to control the first conversion circuit to supply power from the first conversion circuit to the coil when the irreversible demagnetization determination circuit determines that irreversible demagnetization has occurred in the permanent magnet.

13. An aircraft electromechanical system according to any one of claims 1 to 12, wherein the first electric machine is a generator mechanically connected to a rotating shaft of the gas turbine engine, and the second electric machine is an electric motor of an electric accessory used to operate the gas turbine engine.

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