Propulsion system, propulsion control device, and propulsion control program

Abstract

To provide a propulsion system which enables improvement of safety of a movable body, and to provide a propulsion controller and a propulsion control program.SOLUTION: In an inverter device 80, an inverter high voltage part 86 is housed in an inverter housing 90. The inverter housing 90 has an inverter opening 92 and an inverter lid part 95. The inverter lid part 95 covers the inverter opening 92 so as to hide the inverter high voltage part 86. When a control mode of a flight control device 40 is set to an interlock mode, electric power supply from a battery 31 to a motor 61 is blocked along with opening of the inverter lid part 95. When the control mode is set to an interlock release mode, electric power supply from the battery 31 to the motor 61 is not blocked even if the inverter lid part 95 is opened. The control mode is set to the interlock release mode while an eVTOL 10 is flying.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The disclosure in this specification relates to a propulsion system, a propulsion control device, and a propulsion control program. [Background technology]

[0002] Patent Document 1 describes a system for controlling a motor. In this system, a control unit, which is a high-voltage device, is housed in a housing box. When the cover of the housing box is opened, the high-voltage power supplied to the control unit is cut off by an interlock circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-112902 Summary of the Invention [Problem to be solved by the invention]

[0004] A motor is sometimes mounted on an aircraft as a drive source for propelling the aircraft. For example, in a configuration in which the system of Patent Document 1 is mounted on an aircraft, if the cover of the storage box is opened due to an unintended external force or the like, the high-voltage power is cut off by the interlock circuit even while the aircraft is in flight. In this configuration, the motor drive stops when the high-voltage power is cut off, raising concerns that the aircraft's safety may be reduced, such as by insufficient propulsion power.

[0005] The main objective of the present disclosure is to provide a propulsion system, a propulsion control device, and a propulsion control program that can improve the safety of an aircraft. [Means for solving the problem]

[0006] The multiple aspects disclosed in this specification employ different technical means to achieve their respective objectives. Furthermore, the reference symbols in parentheses in the claims and this section are merely examples showing the correspondence between specific means described in the embodiments below as one aspect, and do not limit the technical scope.

[0007] In order to achieve the above object, the disclosed embodiment comprises: A propulsion system (30) for propelling an air vehicle (10), comprising: a motor (61) that is driven by power supplied from a power supply unit (31) to propel the aircraft; a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) containing a drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and that covers the opening so as to hide the drive voltage unit; an interlock unit (S104, S608) that sets a control mode for controlling the power supply from the power supply unit to the motor to an interlock mode for cutting off the power supply from the power supply unit to the motor so that application of a drive voltage to the drive voltage unit is stopped when the housing lid is opened; an interlock release unit (S111, S604) that releases the interlock mode when the aircraft is in flight; It is a propulsion system equipped with

[0008] According to the above propulsion system, when the control mode is in interlock mode, the application of drive voltage to the drive voltage unit is stopped when the housing lid is opened. In this case, even if the drive voltage unit is exposed through the opening of the drive housing, the safety of workers and others is prevented from being reduced. Furthermore, when the aircraft is in flight, the interlock mode is released. In this case, even if the housing lid is opened unintentionally, the power supply from the power supply unit to the motor is not cut off due to the interlock mode. Therefore, the safety of the aircraft is prevented from being reduced, such as a lack of propulsive force when the housing lid is opened. As described above, the safety of the aircraft can be improved.

[0009] The disclosed aspects include: a motor (61) that drives the flying object (10) using power supplied from the power supply unit (31); a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) containing a drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and that covers the opening so as to hide the drive voltage unit; A propulsion control device (40) for controlling a propulsion system (30) having: an interlock unit (S104, S608) that sets a control mode for controlling the power supply from the power supply unit to the motor to an interlock mode for cutting off the power supply from the power supply unit to the motor so that application of a drive voltage to the drive voltage unit is stopped when the housing lid is opened; an interlock release unit (S111, S604) that releases the interlock mode when the aircraft is in flight; This is a propulsion control device equipped with the above.

[0010] The above-described propulsion control device can improve the safety of the flying vehicle, similarly to the above-described propulsion system.

[0011] The disclosed aspects include: a motor (61) that drives the flying object (10) using power supplied from the power supply unit (31); a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) containing a drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and that covers the opening so as to hide the drive voltage unit; a propulsion control program (44) for controlling a propulsion system (30) having: At least one processing section (42) As a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode is set to cut off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened (S104, S608); This is a propulsion control program that releases the interlock mode when the aircraft is in flight (S111, S604).

[0012] The propulsion control program can improve the safety of the aircraft, similar to the propulsion system. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the configuration of an eVTOL in a first embodiment. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the propulsion system. [Figure 3] FIG. 2 is a diagram showing a circuit configuration of an inverter device. [Figure 4] FIG. 4 is a diagram showing the circuit configuration of a lid detection circuit. [Figure 5] 4 is a flowchart showing the procedure of flight control processing. [Figure 6] 4 is a flowchart showing the procedure of a discharge control process. [Figure 7]FIG. 10 is a diagram showing the circuit configuration of a lid detection circuit in a second embodiment. [Figure 8] 4 is a flowchart showing the procedure of a discharge control process. [Figure 9] FIG. 10 is a block diagram showing the electrical configuration of a propulsion system according to a third embodiment. [Figure 10] FIG. 10 is a block diagram showing the electrical configuration of a propulsion system according to a fourth embodiment. [Figure 11] 4 is a flowchart showing the procedure of a discharge control process. [Figure 12] 10 is a flowchart showing the procedure of a discharge control process in a fifth embodiment. [Figure 13] 13 is a flowchart showing the procedure of flight control processing in the sixth embodiment. [Figure 14] FIG. 10 is a diagram showing the circuit configuration of another propulsion system. [Figure 15] FIG. 13 is a diagram showing a circuit configuration of an inverter device according to a seventh embodiment. [Figure 16] 4 is a flowchart showing the procedure of a discharge control process. [Figure 17] FIG. 10 is a diagram for explaining a top on-current. [Figure 18] FIG. 10 is a diagram for explaining a bottom on-current. [Figure 19] 10 is a timing chart for explaining how an upper parasitic voltage and a lower parasitic voltage change; [Figure 20] FIG. 13 is a diagram showing a circuit configuration of an inverter device according to an eighth embodiment. [Figure 21] 4 is a flowchart showing the procedure of a discharge control process. [Figure 22] 10 is a flowchart showing the procedure of a first discharge process. [Figure 23] 10 is a flowchart showing the procedure of a second discharge process. [Figure 24] 10 is a timing chart for explaining how an upper parasitic voltage and a lower parasitic voltage change; [Figure 25] 13 is a flowchart showing the procedure of a discharge control process in the ninth embodiment. [Figure 26]10 is a timing chart for explaining how an upper parasitic voltage and a lower parasitic voltage change; [Figure 27] 20 is a flowchart showing the procedure of a discharge control process in a tenth embodiment. [Figure 28] 10 is a timing chart for explaining how an upper parasitic voltage and a lower parasitic voltage change; [Figure 29] FIG. 23 is a diagram showing the circuit configuration of an inverter device according to an eleventh embodiment. [Figure 30] FIG. 23 is a diagram showing the circuit configuration of an inverter device according to a twelfth embodiment. [Figure 31] 4 is a flowchart showing the procedure of flight control processing. [Figure 32] 22 is a flowchart showing the procedure of flight control processing in the thirteenth embodiment. [Figure 33] 23 is a flowchart showing the procedure of flight control processing in the fourteenth embodiment. [Figure 34] 10 is a flowchart showing the procedure of a recovery process. [Figure 35] 22 is a flowchart showing the procedure of flight control processing in the fifteenth embodiment. [Figure 36] 10 is a flowchart showing the procedure of a total shutoff process. [Figure 37] FIG. 23 is a diagram showing the circuit configuration of an inverter device according to a sixteenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0015] First Embodiment The propulsion system 30 shown in FIG. 1 is mounted on the eVTOL 10. The eVTOL 10 is an electric vertical take-off and landing aircraft. An electric vertical take-off and landing aircraft is an electric vertical take-off and landing aircraft that is capable of vertical take-off and landing. eVTOL is an abbreviation for electric Vertical Take-Off and Landing aircraft. The eVTOL 10 is an electric air vehicle that flies in the atmosphere and is sometimes referred to as an electric air vehicle. The eVTOL 10 is also an electric aircraft and is sometimes referred to as an electric aircraft. The eVTOL 10 is a manned air vehicle that carries a crew member. The crew member of the eVTOL 10 includes a pilot who operates or drives the vehicle. The propulsion system 30 is a system that drives the eVTOL 10 to propel it. The propulsion system 30 is sometimes referred to as a flight system.

[0016] The eVTOL 10 has an airframe 11 and a propeller 20. The airframe 11 has an airframe main body 12 and wings 13. The airframe main body 12 is the fuselage of the airframe 11 and has a shape that extends, for example, in the front-to-rear direction. The airframe main body 12 has a crew cabin 14 for passengers to ride in. The wings 13 extend from the airframe main body 12 and multiple wings 13 are provided on the airframe main body 12. The wings 13 are fixed wings. The multiple wings 13 include main wings, a tail, etc.

[0017] The eVTOL 10 has a cabin. The cabin is provided inside the eVTOL 10. For example, the cabin is the internal space of the aircraft body 12, and is formed by the aircraft body 12. The cabin can be a crew cabin 14 or a cargo bay. The crew cabin 14 can be a passenger cabin or a pilot cabin. The crew cabin 14 is provided with seats for the crew to sit in. The crew cabin 14 does not have to have a crew on board, and may store cargo.

[0018] A plurality of propellers 20 are provided on the airframe 11. The eVTOL 10 is a multicopter having at least three propellers 20. For example, at least six propellers 20 are provided on the airframe 11. The propellers 20 are provided on each of the airframe body 12 and the wings 13. The propellers 20 rotate around a propeller axis. The propeller axis is, for example, the center line of the propeller 20. The propellers 20 can generate thrust and lift for the eVTOL 10. The propellers 20 are sometimes referred to as rotors or rotating blades.

[0019] The eVTOL 10 has multiple propellers 20, making it easier to maintain aircraft balance. Even if the propeller output of one propeller 20 is unintentionally reduced, the eVTOL 10 can continue flying using the remaining propellers 20. Propeller output includes the rotation speed and torque of the propellers 20.

[0020] The propeller 20 has blades, a boss, and a propeller shaft. A plurality of blades are arranged in the circumferential direction of the propeller axis. The boss connects the plurality of blades. The propeller shaft is the rotation axis of the propeller 20 and extends from the boss along the propeller axis.

[0021] Flight modes of the eVTOL 10 include vertical takeoff, vertical landing, cruise, hovering, etc. Flight modes are sometimes referred to as flight modes. In vertical takeoff, the eVTOL 10 can take off without running. In vertical takeoff, the eVTOL 10 may rise vertically or may rise diagonally upward. In vertical landing, the eVTOL 10 can land without running. In vertical landing, the eVTOL 10 may descend vertically or may descend diagonally downward.

[0022] Cruising is sometimes referred to as horizontal flight. In cruising, the eVTOL 10 may fly horizontally without moving vertically, or may fly horizontally while moving vertically. Hovering is sometimes referred to as stationary flight. In hovering, the eVTOL 10 may fly as if stationary at a predetermined position in the air, or the eVTOL 10 may deviate vertically or horizontally from the predetermined position.

[0023] The flight modes of the eVTOL10 also include lift. In lift, the eVTOL10 moves in the vertical direction. As a lift, the eVTOL10 may rise diagonally upward or may descend diagonally downward. The eVTOL10 takes off vertically by lifting upward. The eVTOL10 lands vertically by lifting downward.

[0024] The eVTOL 10 is a tilt rotor aircraft. In the eVTOL 10, the tilt angle of the propeller 20 is adjustable. In the eVTOL 10, one propeller 20 can function as both a lift propeller and a cruise propeller. For example, when the eVTOL 10 lifts, the tilt angle is adjusted so that the propeller 20 functions as a lift rotor. When the eVTOL 10 cruises, the tilt angle is adjusted so that the propeller 20 functions as a cruise rotor. Note that the eVTOL 10 does not have to be a tilt rotor aircraft. For example, the eVTOL 10 may have separate propellers 20 for lift and cruise.

[0025] The eVTOL 10 has a battery 31, a distributor 32, a communication unit 34, a flight control device 40, and an EPU 50. The battery 31, the distributor 32, the communication unit 34, the flight control device 40, and the EPU 50 are included in the propulsion system 30. It is sufficient that the propulsion system 30 includes at least the flight control device 40 and the EPU 50. The flight control device 40 is sometimes referred to as a flight controller.

[0026] The battery 31 is connected to the EPU 50 so that it can be electrically connected. The battery 31 is a power supply unit that supplies power to the EPU 50 and corresponds to a power supply unit. The battery 31 is a DC voltage source that applies a DC voltage to the EPU 50. The battery 31 has a secondary battery that can be charged and discharged. Examples of such secondary batteries include a lithium ion battery and a nickel-metal hydride battery. The battery 31 is capable of storing power and corresponds to a power storage device. Note that a fuel cell, a generator, or the like may be used as the power supply unit in addition to or instead of the battery 31.

[0027] The distributor 32 is electrically connected to the battery 31 and the plurality of EPUs 50. The distributor 32 distributes power from the battery 31 to the plurality of EPUs 50. The battery 31 is electrically connected to the plurality of EPUs 50 via the distributor 32. The battery 31 supplies power to the EPUs 50 via the distributor 32.

[0028] The communication unit 34 is a communication device capable of wireless communication with an external device. The external device is a device located away from the eVTOL 10. Examples of external devices include communication devices provided in external facilities on the ground and communication devices provided in other flying vehicles. Examples of external facilities include a control center and a management center. The communication unit 34 is capable of communication with the flight control device 40. The communication unit 34 is connected to the flight control device 40 so that it can communicate via wired communication. Note that the communication unit 34 may also be capable of wireless communication with the flight control device 40.

[0029] 1 and 2, the EPU 50 is a device that drives the propeller 20 to rotate, and corresponds to a drive device. EPU is an abbreviation for Electric Propulsion Unit. The EPU 50 is sometimes referred to as an electric drive device or an electric drive system. An EPU 50 is provided individually for each of the multiple propellers 20. The EPUs 50 are arranged next to the propellers 20 along the propeller axis. All of the multiple EPUs 50 are fixed to the airframe 11. The EPUs 50 support the propellers 20 so that they can rotate. The EPUs 50 are connected to the propellers 20. The propellers 20 are fixed to the airframe 11 via the EPUs 50.

[0030] As shown in FIG. 2 , the eVTOL 10 has a propulsion device 100. The propulsion device 100 is formed to include a propeller 20 and an EPU 50. The propulsion device 100 is a device for propelling the eVTOL 10. The propulsion device 100 causes the eVTOL 10 to fly by rotating the propeller 20. The eVTOL 10 is also a moving body that moves using the propulsion device 100. A plurality of propulsion devices 100 are provided on the eVTOL 10. One propulsion device 100 includes one propeller 20 and one EPU 50 for driving the propeller 20. Note that of the propeller 20 and the EPU 50, only the EPU 50 may be referred to as the propulsion device 100.

[0031] The EPU 50 has a motor device 60 and an inverter device 80. The motor device 60 has a motor 61 and a motor housing 70. The motor housing 70 is a housing and houses the motor 61. The motor 61 is a multi-phase AC motor. The motor 61 is a multi-phase AC rotating electric machine. The motor 61 is the flight drive source for the eVTOL 10 and functions as an electric motor. The motor 61 drives and rotates the propeller 20, enabling the eVTOL 10 to fly. The motor 61 is a flight motor for flying the eVTOL 10. The EPU 50 drives and rotates the propeller 20 by driving the motor 61. A brushless motor, for example, is used as the motor 61.

[0032] The motor 61 has a motor stator 62 and a motor rotor 63. The motor 61 has the motor stator 62. The motor stator 62 is a stator and is fixed to the motor housing 70. The motor rotor 63 rotates relative to the motor stator 62. The rotation of the motor rotor 63 is sometimes referred to as the rotation of the motor 61. The motor 61 is, for example, an axial gap motor. In the motor 61, the motor stator 62 and the motor rotor 63 are aligned in the axial direction of the motor 61. The motor 61 has a motor shaft that rotates together with the motor rotor 63. The motor shaft is rotatably supported by the motor housing 70 or the like.

[0033] The motor 61 is driven by supplying power to the motor stator 62. The motor stator 62 has a stator coil. The stator coil is a multi-phase coil. The stator coil forms an armature. When power is supplied to the motor stator 62, a current flows through the stator coil, causing the motor rotor 63 to rotate. Driving the motor 61 to rotate the motor rotor 63 is sometimes referred to as rotational driving of the motor 61. Rotational driving of the motor 61 is sometimes simply referred to as driving the motor 61.

[0034] The inverter device 80 drives the motor device 60 by supplying power to the motor device 60. The inverter device 80 is a drive unit for driving the motor 61 and corresponds to a motor drive unit. The inverter device 80 has an inverter circuit 85 and an inverter housing 90. The inverter circuit 85 converts the power supplied to the motor 61. The inverter circuit 85 may also be referred to as an inverter, power conversion unit, or control circuit. The inverter circuit 85 performs power conversion for each of the multiple phases. The motor 61 is driven in accordance with the voltage and current supplied from the inverter circuit 85. The inverter housing 90 is a housing that houses the inverter circuit 85 and the inverter control unit 81, which will be described later. The inverter housing 90 corresponds to a drive housing.

[0035] The inverter device 80 has an inverter control unit 81. The inverter control unit 81 performs motor control via an inverter circuit 85. The motor control is control for driving the motor 61. The inverter control unit 81 also performs propulsion control. The propulsion control is control for driving the propulsion device 100. The propulsion control includes motor control. The propulsion control is also control for controlling the EPU 50, and is sometimes referred to as EPU control.

[0036] The inverter control unit 81 has, for example, an ECU. ECU is an abbreviation for Electronic Control Unit. The inverter control unit 81 has a processor 82, a memory 83, and a program 84. The inverter control unit 81 is mainly configured with a computer. This computer has the processor 82, memory 83, an input / output interface, a bus connecting these, etc. The memory 83 stores the program 84. The program 84 is a program for performing propulsion control. The program 84 corresponds to a propulsion control program.

[0037] The processor 82 is hardware for arithmetic processing coupled to the memory 83. The processor 82 executes various processes by accessing the memory 83. The memory 83 is a storage medium that stores a control program and the like. For example, the memory 83 is a non-transitory tangible storage medium that non-temporarily stores computer-readable programs and data. The non-transitory tangible storage medium is a non-transitory tangible storage medium, and is realized by a semiconductor memory, a magnetic disk, or the like. The program 84 includes computer-readable instructions that cause the processor 82 to execute various functions. The processor 82 is a processing unit that executes predetermined processes by executing instructions included in the program 84.

[0038] The inverter control unit 81 controls the motor according to the required output. The required output is the motor output required of the inverter control unit 81. The required output includes, for example, the required torque required for the output torque. The required output is included in a command signal or the like output by the flight control device 40 to the inverter control unit 81. The inverter control unit 81 adjusts the motor output according to the required output. The required output and required torque are sometimes referred to as target output and target torque. Note that torque, current, voltage, motor rotation speed, etc. may also be used as the motor output.

[0039] The inverter control unit 81 controls the motor using command signals from the flight control device 40 and detection signals from various sensors. The various sensors are communicatively connected to the inverter control unit 81. The various sensors include a motor sensor, a battery sensor, and an inverter sensor. The motor sensor is a temperature sensor or the like provided in the motor device 60. The battery sensor is a temperature sensor or the like provided in the battery 31. The inverter sensor is a temperature sensor or the like provided in the inverter device 80.

[0040] The flight control device 40 is communicatively connected to the inverter control unit 81. The flight control device 40 and the inverter control unit 81 may be capable of wireless communication. The flight control device 40 performs overall control to coordinate the drive of the multiple propulsion devices 100. The overall control coordinates the propulsion controls performed by each of the multiple inverter control units 81. The flight control device 40 performs flight control. Flight control is control for flying the eVTOL 10. As flight control, the flight control device 40 controls the propulsion system 30 and EPU 50. Flight control is also control for propelling the eVTOL 10, and is sometimes referred to as propulsion control. The flight control device 40 corresponds to a propulsion control device.

[0041] The flight control device 40 has, for example, an ECU. The flight control device 40 has a processor 42, a memory 43, and a program 44. The flight control device 40 is mainly composed of a computer. This computer has the processor 42, the memory 43, an input / output interface, a bus connecting these, etc. The memory 43 stores the program 44. The program 44 is a program for performing flight control.

[0042] The processor 42 is hardware for arithmetic processing coupled to the memory 43. The processor 42 executes various processes by accessing the memory 43. The memory 43 is a storage medium that stores a control program and the like. For example, the memory 43 is a non-transient tangible storage medium that non-temporarily stores computer-readable programs and data. The program 44 includes computer-readable instructions that cause the processor 42 to execute various functions. The processor 42 is a processing unit that executes predetermined processes by executing instructions included in the program 44.

[0043] The flight control device 40 outputs information necessary for propulsion control to the inverter control unit 81. The flight control device 40 is a higher-level ECU for the inverter control unit 81. The flight control device 40 individually controls the multiple propulsion devices 100 according to the flight mode of the eVTOL 10, etc. The flight control device 40 can individually adjust the output of each propulsion device 100. For example, the flight control device 40 outputs a required output to each of the multiple propulsion devices 100. The required output is the output required of the propulsion device 100. Examples of the required output include the required torque required for the motor 61. Note that torque, current, voltage, motor rotation speed, etc. may also be used as the required output.

[0044] The flight control device 40 performs flight control in accordance with the flight state of the eVTOL 10 and detection signals from various sensors. The flight state of the eVTOL 10 includes the flight mode and the flight attitude of the eVTOL 10. The various sensors are connected to the flight control device 40 so as to be able to communicate with each other.

[0045] In this embodiment, the propulsion device 100 has a plurality of inverter devices 80. For example, the propulsion device 100 has a first inverter device 801 and a second inverter device 802 as the inverter devices 80.

[0046] In the propulsion device 100, both inverter devices 801 and 802 control the motor 61. In the inverter devices 801 and 802, each inverter circuit 85 supplies power to the motor stator 62. In the inverter devices 801 and 802, each inverter control unit 81 controls the motor. The motor 61 is a 2×n-phase motor, where n is a natural number. One of the inverter devices 801 and 802 drives the n-phase motor, and the other drives the remaining n-phase motor. For example, the motor 61 has 2×n-phase coils as motor coils. In the inverter devices 801 and 802, one inverter circuit 85 supplies power to the n-phase coil, and the other inverter circuit 85 supplies power to the remaining n-phase coils.

[0047] In Figure 2, the motor unit 60 is shown as MOTU, the motor stator 62 as STA, and the motor rotor 63 as ROT. The inverter unit 80 is shown as MCU, the inverter circuit 85 as INV, and the inverter control unit 81 as ICD. The processor 82 is shown as PRO, the memory 83 as MEM, and the program 84 as PG. The flight control device 40 is shown as FCD, the processor 42 as PRO, the memory 43 as MEM, and the program 44 as PG.

[0048] The inverter device 80 has a P line 111, an N line 112, and an output line 113. The P line 111 and the N line 112 are electrically connected to the battery 31 and the inverter circuit 85. The P line 111 is electrically connected to the positive electrode of the battery 31. The N line 112 is electrically connected to the negative electrode of the battery 31. In the battery 31, the positive electrode is the high-potential electrode, and the negative electrode is the low-potential electrode. The P line 111 and the N line 112 are power lines for supplying power from the battery 31 to the inverter circuit 85. The P line 111 is a high-potential power line and may be referred to as a high-potential line. The N line 112 is a low-potential power line and may be referred to as a low-potential line.

[0049] The output line 113 is a power line for supplying power from the inverter circuit 85 to the motor 61. The output line 113 is electrically connected to the motor 61 and the inverter circuit 85. For example, the output line 113 is electrically connected to the motor stator 62.

[0050] The inverter device 80 has a smoothing capacitor 114. The smoothing capacitor 114 is a capacitor that smoothes the DC voltage supplied from the battery 31. The smoothing capacitor 114 is connected to the P line 111 and the N line 112 between the battery 31 and the inverter circuit 85. The smoothing capacitor 114 is connected in parallel to the inverter circuit 85.

[0051] The inverter circuit 85 is a power conversion circuit, for example, a DC-AC conversion circuit. The inverter circuit 85 has upper and lower arm circuits 115 for multiple phases. For example, the inverter circuit 85 has an upper and lower arm circuit 115 for each of the U phase, V phase, and W phase. The upper and lower arm circuit 115 has an upper arm switch 116 and a lower arm switch 117. The arm switches 116 and 117 are connected in series to the battery 31. The upper arm switch 116 is connected to the P line 111 so as to be conductive. The lower arm switch 117 is connected to the N line 112 so as to be conductive.

[0052] The arm switches 116 and 117 are transistors such as MOSFETs and IGBTs. MOSFET is an abbreviation for Metal-Oxide-Semiconductor Field-Effect Transistor. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. The arm switches 116 and 117 are switch elements that can convert power by switching. The switch elements are semiconductor elements such as power elements. The arm switches 116 and 117 are conversion switches for converting power. A freewheeling diode is connected in antiparallel to the arm switches 116 and 117.

[0053] The output line 113 is electrically connected to the upper and lower arm circuits 115 in each of the multiple phases. The output line 113 is connected between the upper arm switch 116 and the lower arm switch 117. The inverter circuit 85 of the first inverter device 801 and the inverter circuit 85 of the second inverter device 802 are connected in parallel to the battery 31. A plurality of output lines 113 are provided for each of the first inverter device 801 and the second inverter device 802.

[0054] 2, the inverter housing 90 has an inverter outer wall 91 and an inverter lid 95. The inverter outer wall 91 forms the outer and inner surfaces of the inverter housing 90. The inverter outer wall 91 is made of a metal material or the like. The inverter outer wall 91 houses the inverter circuit 85 and the inverter control unit 81.

[0055] An inverter opening 92 is provided in the inverter outer wall 91. The inverter opening 92 is an opening formed in the inverter outer wall 91. For example, the inverter opening 92 is provided on the outer peripheral surface of the inverter outer wall 91. The inverter opening 92 is an opening for maintenance. A worker such as a pilot can access the inside of the inverter device 80 through the inverter opening 92 to perform maintenance on the inverter device 80.

[0056] The inverter lid 95 is a lid that covers the inverter opening 92. The inverter lid 95 is formed from a metal material or the like. The inverter lid 95 can open the inverter opening 92. The inverter lid 95 can be moved between an open state in which the inverter opening 92 is open and a closed state in which the inverter opening 92 is closed. The inverter lid 95 is normally in a closed state and is temporarily opened during maintenance or the like. For example, the inverter lid 95 is removably fixed to the inverter outer wall 91 with a fastener such as a knob bolt. The inverter lid 95 is opened when removed from the inverter outer wall 91. The inverter lid 95 corresponds to a housing lid.

[0057] Inverter device 80 has an inverter high voltage section 86 and an inverter low voltage section 87. Inverter high voltage section 86 is a section or component of inverter device 80 to which a drive voltage is applied. The drive voltage is a voltage for driving motor 61. For example, the drive voltage is applied as a high voltage to P line 111. The drive voltage is a voltage higher than a control voltage, which will be described later. The drive voltage is a voltage applied to inverter high voltage section 86 in conjunction with the supply of power from battery 31 to motor 61. The drive voltage is applied to output line 113, power terminals of arm switches 116 and 117, the motor coil, etc.

[0058] Inverter high voltage section 86 is a section in inverter device 80 through which current flows in response to application of a drive voltage. Inverter high voltage section 86 includes high voltage wiring such as bus bars forming lines 111-113, terminal components to which the high voltage wiring is connected, semiconductor components forming arm switches 116 and 117, and capacitor components forming smoothing capacitor 114. Inverter high voltage section 86 corresponds to the drive voltage section.

[0059] Inverter high voltage section 86 has a high voltage facing portion 86a. High voltage facing portion 86a is a portion of inverter high voltage section 86 that is located opposite inverter opening 92. High voltage facing portion 86a is at least a part of inverter high voltage section 86. In inverter high voltage section 86, at least a part of the high voltage wiring, at least a part of the terminal components, at least a part of the semiconductor components, at least a part of the capacitor components, etc. can become high voltage facing portion 86a. High voltage facing portion 86a is located opposite inverter lid portion 95. Inverter lid portion 95 closes inverter opening 92 so as to cover high voltage facing portion 86a. In other words, inverter lid portion 95 covers inverter opening 92 so as to hide at least a part of inverter high voltage section 86.

[0060] The inverter low voltage section 87 is a portion or component of the inverter device 80 to which a control voltage is applied. The control voltage is a voltage for controlling the driving of the motor 61. For example, the control voltage is applied as a low voltage to the inverter control section 81. The control voltage is also applied to the control terminals of the arm switches 116 and 117. The inverter low voltage section 87 includes electronic components such as a circuit board that forms the inverter control section 81, low voltage wiring such as communication lines, terminal components to which the low voltage wiring is connected, and sensor components that form various sensors.

[0061] The inverter low-voltage section 87 has a low-voltage facing portion 87a. The low-voltage facing portion 87a is a portion of the inverter low-voltage section 87 that is located opposite the inverter opening 92. The low-voltage facing portion 87a is at least a part of the inverter low-voltage section 87. In the inverter low-voltage section 87, at least a part of the electronic components, at least a part of the low-voltage wiring, at least a part of the terminal components, at least a part of the sensor components, etc. can become the low-voltage facing portion 87a. The low-voltage facing portion 87a is located opposite the inverter lid portion 95. The inverter lid portion 95 closes the inverter opening 92 so as to cover the low-voltage facing portion 87a. In other words, the inverter lid portion 95 covers the inverter opening 92 so as to hide at least a part of the inverter low-voltage section 87.

[0062] When the inverter lid 95 is in the open state, an operator can access the inverter high-voltage section 86 and the inverter low-voltage section 87 through the inverter opening 92. In this case, the high-voltage facing section 86a and the low-voltage facing section 87a of the inverter device 80 are exposed to the outside of the inverter device 80 through the inverter opening 92. This allows an operator to perform maintenance on the inverter high-voltage section 86 and the inverter low-voltage section 87 through the inverter opening 92. For example, an operator can replace components included in the inverter high-voltage section 86 and the inverter low-voltage section 87 through the inverter opening 92.

[0063] The inverter device 80 has an opening peripheral portion 88. The opening peripheral portion 88 is a portion of the inverter device 80 provided around the inverter opening 92. The opening peripheral portion 88 may be a component attached to the high-voltage facing portion 86a, a part of the inverter high-voltage portion 86, a component attached to the low-voltage facing portion 87a, a part of the inverter low-voltage portion 87, or the like. The opening peripheral portion 88 may also be a component attached to the inverter outer wall 91, a part of the inverter outer wall 91, or the like.

[0064] In the inverter device 80, the opening-side contact portion 89 of the opening peripheral portion 88 comes into contact with the lid-side contact portion 97 of the inverter lid portion 95. The opening-side contact portion 89 is part of the opening peripheral portion 88. The lid-side contact portion 97 is part of the inverter lid portion 95. The opening-side contact portion 89 and the lid-side contact portion 97 come into contact with each other when the inverter lid portion 95 is in the closed state, but are separated from each other when the inverter lid portion 95 is in the open state.

[0065] The opening-side contact portion 89 and the lid-side contact portion 97 are provided in the fitting portion where the opening peripheral portion 88 and the inverter lid portion 95 are fitted together. For example, when the inverter lid portion 95 is in the closed state, the convex portion of the inverter lid portion 95 is fitted into the concave portion of the opening peripheral portion 88. The opening-side contact portion 89 is provided on the inner surface of the concave portion of the opening peripheral portion 88. The lid-side contact portion 97 is provided on the outer surface of the convex portion of the inverter lid portion 95. When the convex portion of the inverter lid portion 95 is fitted into the concave portion of the opening peripheral portion 88, the opening-side contact portion 89 and the lid-side contact portion 97 are in contact with each other.

[0066] The opening-side contact portion 89 and the lid-side contact portion 97 are made of a metal material or the like and are electrically conductive. When the opening-side contact portion 89 and the lid-side contact portion 97 are in contact with each other, they are electrically connected to each other.

[0067] In the propulsion device 100, when the inverter lid portion 95 is opened, the power supply from the battery 31 to the motor 61 is cut off. As shown in FIGS. 3 and 4 , the propulsion device 100 has a power supply switch 132. The power supply switch 132 is a switch such as an SMR. SMR is an abbreviation for System Main Relay. The power supply switch 132 can cut off the power supply from the battery 31 to the motor 61. The power supply switch 132 is provided between the battery 31 and the inverter circuit 85. The power supply switch 132 is provided for each of the P line 111 and the N line 112.

[0068] Power supply switch 132 can be switched between an energized state and an interrupted state. When power supply switch 132 is in the energized state, power is supplied from battery 31 to motor 61, and a drive voltage is applied to inverter high voltage unit 86. When power supply switch 132 is in the interrupted state, the power supply from battery 31 to motor 61 is interrupted, and the application of drive voltage to inverter high voltage unit 86 is stopped.

[0069] The power supply switch 132 is provided individually for each of the multiple propulsion devices 100. The power supply switch 132 may be provided integrally with the propulsion device 100, or may be provided independently from the propulsion device 100. In one propulsion device 100, only one power supply switch 132 may be provided for multiple inverter circuits 85, or may be provided individually for each of the multiple inverter circuits 85. The power supply switch 132 may be provided integrally with the inverter device 80, or may be provided independently from the inverter device 80.

[0070] Even when the power supply from the battery 31 to the motor 61 is cut off by the power supply switch 132, the power supply from the battery 31 to the flight control device 40 and the inverter control unit 81 continues. In this case, the flight control device 40 and the inverter control unit 81 can drive the inverter circuit 85 so that the arm switches 116 and 117 turn on and off. In other words, the flight control device 40 and the inverter control unit 81 can control the motor even when the power supply from the battery 31 to the motor 61 is cut off. In FIG. 4, the battery 31 is shown as BAT and the motor 61 as MOT.

[0071] As shown in FIG. 4, the propulsion device 100 has a lid detection circuit 120. The lid detection circuit 120 is a circuit that detects the opening of the inverter lid unit 95. The lid detection circuit 120 is sometimes referred to as a lid detector. The lid detection circuit 120 is communicatively connected to the flight control device 40 via the inverter control unit 81 and a communication path 125. The communication path 125 communicatively connects the inverter control unit 81 and the flight control device 40. The lid detection circuit 120 outputs a detection signal corresponding to the state of the inverter lid unit 95. The detection signal from the lid detection circuit 120 is input to the flight control device 40 via the inverter control unit 81. For example, the lid detection circuit 120 inputs a voltage corresponding to the state of the inverter lid unit 95 to the inverter control unit 81 as a detection signal.

[0072] The lid detection circuit 120 has a lid switch 121 and a detection resistor 122. The detection resistor 122 is formed of a resistive element or the like. A plurality of detection resistors 122 are included in the lid detection circuit 120. The lid switch 121 is opened and closed in accordance with the opening and closing of the inverter lid 95. The lid detection circuit 120 detects the state of the lid switch 121 as the state of the inverter lid 95. The lid switch 121 is provided on the inverter housing 90. For example, when the inverter lid 95 is in a closed state, the lid switch 121 is in an energized state. When the inverter lid 95 is in an open state, the lid switch 121 is in an energized state.

[0073] The lid switch 121 functions as a contact sensor. The opening-side contact portion 89 and the lid-side contact portion 97 form the switch contacts of the lid switch 121. When the opening-side contact portion 89 and the lid-side contact portion 97 come into contact, the contacts of the lid switch 121 come into contact. In this case, the lid detection circuit 120 detects that the inverter lid 95 is in the closed state by the lid switch 121. On the other hand, when the opening-side contact portion 89 and the lid-side contact portion 97 do not come into contact, the contacts of the lid switch 121 come into an open state. In this case, the lid detection circuit 120 detects that the inverter lid 95 is in the open state by the lid switch 121.

[0074] The flight control device 40 performs flight control processing, which will be described with reference to the flowchart in Figure 5. The flight control device 40 repeatedly executes the flight control processing at a predetermined control period.

[0075] The flight control device 40 acquires eVTOL information in step S101 shown in Fig. 5. The eVTOL information is information that indicates the state of the eVTOL 10. Examples of the eVTOL information include information that indicates the flight state of the eVTOL 10 and information that indicates the state of the propulsion device 100. Information that indicates the state of the propulsion device 100 includes the open / closed state of the power supply switch 132 and the drive state of the motor 61. Examples of the eVTOL information include information input to the flight control device 40 from an external device via the communication unit 34.

[0076] In step S102, the flight control device 40 determines whether or not the landing of the eVTOL 10 is complete. The landing of the eVTOL 10 is completed when at least a portion of the eVTOL 10 comes into contact with the ground, or when the attitude of the eVTOL 10 stabilizes after the eVTOL 10 has landed on the ground. For the eVTOL 10, flight ends when landing is complete. When landing of the eVTOL 10 is complete, the flight control device 40 determines that the eVTOL 10 is not in flight but is on the ground.

[0077] When the landing of the eVTOL 10 is complete, the flight control device 40 proceeds to step S104. In step S104, the flight control device 40 turns on the interlock of the inverter cover unit 95. That is, the flight control device 40 enables the interlock for the inverter cover unit 95. For example, the flight control device 40 sets the control mode for controlling the propulsion device 100 to interlock mode. The control mode is a mode for controlling the power supply from the battery 31 to the motor 61. The flight control device 40 performs motor control according to the control mode. The interlock mode is a mode for switching the power supply switch 132 to a cut-off state when the inverter cover unit 95 is opened. In the interlock mode, the power supply from the battery 31 to the motor 61 is cut off by the power supply switch 132 when the inverter cover unit 95 is opened. The function of the flight control device 40 that executes the processing of step S104 corresponds to the interlock unit.

[0078] When the control mode is set to the interlock mode following the completion of landing of the eVTOL 10, the flight control device 40 maintains the control mode in the interlock mode until the eVTOL 10 takes off for the next flight. Note that in Figure 5 etc., interlock is illustrated as IL.

[0079] If the landing of the eVTOL 10 is not complete, the flight control device 40 proceeds to step S103. In step S103, the flight control device 40 determines whether the eVTOL 10 has not yet taken off. The eVTOL 10 may be in a state before takeoff if a portion of the eVTOL 10 is still in contact with the ground, or if the lift generated by the propellers 20 has not yet become large enough to cause the attitude of the eVTOL 10 to become unstable. For the eVTOL 10, being in a state before takeoff does not mean that the eVTOL 10 is not in flight. If the eVTOL 10 has not yet taken off, the flight control device 40 determines that the eVTOL 10 is not in flight but is on the ground. If the eVTOL 10 has not yet taken off, the flight control device 40 proceeds to step S105 while maintaining the control mode in the interlock mode.

[0080] The flight control device 40 may determine whether the eVTOL 10 has not yet taken off by determining whether a flight start command has been received. The flight start command is a command for starting the flight of the eVTOL 10. The flight start command is input to the flight control device 40 from the pilot or an external device. The flight control device 40 determines that the eVTOL 10 has not yet taken off before receiving the flight start command. Furthermore, the flight control device 40 determines that the eVTOL 10 has already taken off after receiving the flight start command.

[0081] If the eVTOL 10 has completed landing or is about to take off, the flight control device 40 determines that the eVTOL 10 is on the ground in interlock mode and proceeds to step S105. In step S105, the flight control device 40 determines whether the inverter lid unit 95 is in the open state. This determination is made using the detection signal of the lid detection circuit 120. An example of a case in which the inverter lid unit 95 is in the open state is when an operator opens the inverter lid unit 95 for maintenance or the like after the eVTOL 10 has completed landing or before takeoff.

[0082] If the inverter cover 95 is in the open state, the flight control device 40 proceeds to step S106. In step S106, the flight control device 40 performs interlock shutdown processing. In the interlock shutdown processing, when the control mode is in interlock mode, processing is performed to shut off the power supply from the battery 31 to the motor 61 in response to the opening of the inverter cover 95. For example, when the inverter cover 95 transitions from the closed state to the open state, the flight control device 40 transitions the power supply switch 132 from the conducting state to the cut-off state. In this state, the application of drive voltage to the inverter high voltage unit 86 is stopped. On the other hand, when the inverter cover 95 remains open, the flight control device 40 maintains the power supply switch 132 in the cut-off state. In this state, a state in which drive voltage is not applied to the inverter high voltage unit 86 is maintained.

[0083] The flight control device 40 performs discharge control processing in step S107. In the propulsion device 100, after the power supply from the battery 31 to the motor 61 is cut off, residual power may remain in the inverter high voltage unit 86, etc. The residual power is power generated by a residual charge remaining in the inverter high voltage unit 86. For example, the residual power is likely to remain in capacitor components such as the smoothing capacitor 114. In the inverter high voltage unit 86, the residual power may generate a residual voltage. If residual power remains in the smoothing capacitor 114, the residual power may generate a residual voltage in the smoothing capacitor 114. Furthermore, the residual voltage generated in the smoothing capacitor 114 may be applied to the lines 111 to 113, the arm switches 116 and 117, etc.

[0084] In the discharge control process, a process is performed to release residual charge from inverter high voltage unit 86. By performing the discharge control process, for example, residual power in smoothing capacitor 114 is discharged. In inverter high voltage unit 86, the residual charge flows to motor 61 as a discharge current, and the residual power is discharged by motor 61. The function of executing the process of step S107 in flight control device 40 corresponds to the discharge execution unit. Residual power decreases over time due to natural discharge in inverter high voltage unit 86. In the discharge control process, the residual charge in inverter high voltage unit 86 is forcibly discharged so that the residual power in inverter high voltage unit 86 is eliminated in a shorter time than natural discharge. The discharge control process of step S107 will be described later.

[0085] If the inverter cover 95 is not in the open state, the flight control device 40 determines that the inverter cover 95 is in the closed state and proceeds to step S108. In step S108, the flight control device 40 performs power supply processing in interlock mode. In the power supply processing in interlock mode, processing is performed to supply power from the battery 31 to the motor 61. For example, when the inverter cover 95 transitions from the open state to the closed state, the flight control device 40 transitions the power supply switch 132 from the cut-off state to the energized state. On the other hand, when the inverter cover 95 remains in the closed state, the flight control device 40 maintains the power supply switch 132 in the energized state.

[0086] If it is determined in steps S102 and S103 that the eVTOL 10 is in flight, the flight control device 40 proceeds to step S109. In step S109, the flight control device 40 determines whether or not takeoff of the eVTOL 10 has started. Takeoff of the eVTOL 10 may have started when at least a portion of the eVTOL 10 has lifted off, or when the lift generated by the propellers 20 has become so large that the attitude of the eVTOL 10 has become unstable. The start of takeoff of the eVTOL 10 means that the eVTOL 10 is in flight. If takeoff of the eVTOL 10 has started, the flight control device 40 determines that the eVTOL 10 is not on the ground and is in flight.

[0087] When takeoff of the eVTOL 10 has begun, the flight control device 40 proceeds to step S111. In step S111, the flight control device 40 turns off the interlock of the inverter cover unit 95. That is, the flight control device 40 disables the interlock for the inverter cover unit 95. For example, the flight control device 40 sets the control mode to interlock release mode. The interlock release mode is a mode for maintaining the power feed switch 132 in an energized state even when the inverter cover unit 95 is opened. In the interlock release mode, the power supply from the battery 31 to the motor 61 continues without being interrupted even when the inverter cover unit 95 is opened. The interlock release mode corresponds to the continuation mode. The function of the flight control device 40 that executes the processing of step S111 corresponds to the interlock release unit.

[0088] When the control mode is set to interlock release mode as the eVTOL 10 begins takeoff, the flight control device 40 maintains the control mode in interlock release mode until the eVTOL 10 completes its current flight and lands at a destination or the like. Note that states in which the interlock is disabled by interlock release mode include a state in which the flight control device 40 acquires information on whether the inverter lid unit 95 is open or closed, and a state in which the flight control device 40 does not acquire information on whether the inverter lid unit 95 is open or closed. Regardless of whether the flight control device 40 acquires information on whether the inverter lid unit 95 is open or closed, in interlock release mode, the power supply switch 132 remains energized even if the lid detection circuit 120 erroneously detects that the inverter lid unit 95 is open. Furthermore, when the flight control device 40 does not acquire information on whether the inverter lid unit 95 is open or closed, the flight control device 40 may or may not acquire a detection signal from the lid detection circuit 120.

[0089] If takeoff of the eVTOL 10 has not commenced, the flight control device 40 proceeds to step S110. In step S110, the flight control device 40 determines whether the eVTOL 10 has not yet landed. The eVTOL 10 may have not yet touched the ground, or the lift generated by the propellers 20 may still be large enough to cause the attitude of the eVTOL 10 to become unstable even after the eVTOL 10 has landed on the ground. For the eVTOL 10, the state before landing is equivalent to the state in flight. If the eVTOL 10 has not yet landed, the flight control device 40 determines that the eVTOL 10 is not on the ground and is in flight. If the eVTOL 10 has not yet landed, the flight control device 40 proceeds to step S112 while maintaining the control mode in the interlock release mode.

[0090] When the eVTOL 10 has started to take off or when the eVTOL 10 is about to land, the flight control device 40 determines that the eVTOL 10 is flying in interlock release mode and proceeds to step S112. In step S112, the flight control device 40 performs power supply processing in interlock release mode. In the power supply processing in interlock release mode, processing is performed to supply power from the battery 31 to the motor 61 regardless of whether the inverter lid unit 95 is open or closed. In other words, by maintaining the power supply switch 132 in a conducting state regardless of the detection signal from the lid detection circuit 120, a state in which a drive voltage is applied to the inverter high voltage unit 86 is maintained.

[0091] Next, the discharge control process will be described with reference to the flowchart in Figure 6. The flight control device 40 performs d-axis drive process in step S201 shown in Figure 6. In the d-axis drive process, a process is carried out to release the residual power of the inverter high voltage unit 86 to the motor 61. In the d-axis drive process, a discharge current flows from the inverter high voltage unit 86 to the motor coil, thereby discharging the residual power of the inverter high voltage unit 86. The function of the flight control device 40 that executes the process of step S201 corresponds to the motor discharge unit.

[0092] In the propulsion device 100, vector control is performed as motor control. For example, the flight control device 40 performs motor control via the inverter control unit 81. The flight control device 40 controls a current vector in a dq coordinate system as vector control. In vector control, a d-axis current and a q-axis current are used. The current vector is a current flowing through the motor 61 and is sometimes referred to as a motor current. The d-axis current is a component in the current vector that generates magnetic flux. The q-axis current is a component in the current vector that generates torque.

[0093] In the d-axis drive process, the flight control device 40 discharges the residual power of the inverter high-voltage unit 86 so that the propeller 20 does not rotate. In the d-axis drive process, the discharge current is controlled so that the motor 61 does not generate torque to rotate the propeller 20. For example, the flight control device 40 performs vector control to achieve d-axis energization, thereby driving the motor 61 along the d-axis with the discharge current. In d-axis energization, only the d-axis current of the d-axis and q-axis currents is output to the motor 61 so that the motor rotor 63 does not rotate. The flight control device 40 performs d-axis energization by controlling the inverter circuit 85 so that the torque and q-axis current of the motor 61 become zero. The function of the flight control device 40 that executes the process of step S201 corresponds to the stop discharge unit.

[0094] In step S202, the flight control device 40 counts the discharge counter Cd. The flight control device 40 increments the discharge counter Cd by a predetermined increment. This increment is sometimes referred to as the count-up amount. For example, the flight control device 40 sets the increment to 1 and increments the discharge counter Cd by 1. The count value of the discharge counter Cd indicates the duration of discharge of the inverter high voltage unit 86 due to the d-axis drive process. In the propulsion device 100, the larger the discharge counter Cd, the more the discharge of the inverter high voltage unit 86 progresses, and the more likely the residual power of the inverter high voltage unit 86 is to decrease. The discharge counter Cd is set in the memory 43 or the like.

[0095] In step S203, the flight control device 40 determines whether the discharge counter Cd has reached the counter threshold TCd. The counter threshold TCd is a value determined in advance through testing or the like and stored in the memory 43 or the like. The counter threshold TCd is a value indicating the upper limit of the duration of discharge due to the d-axis drive process, and is a value indicating the time required for the discharge of the inverter high voltage unit 86 due to the d-axis drive process to be completed. For example, the counter threshold TCd is a value indicating the time required for the residual power of the inverter high voltage unit 86 to become zero. When the discharge counter Cd has reached the counter threshold TCd, the flight control device 40 determines that the residual power of the inverter high voltage unit 86 has become zero. In the inverter high voltage unit 86, the residual voltage also becomes zero as the residual power becomes zero.

[0096] When the discharge counter Cd reaches the counter threshold value TCd, the flight control device 40 determines that the discharge of the inverter high voltage unit 86 is complete and proceeds to step S204. In step S204, the flight control device 40 performs d-axis drive stop processing. In the d-axis drive stop processing, processing is performed to end the d-axis drive processing. In the d-axis drive stop processing, drive of the inverter circuit 85 is stopped. For example, the flight control device 40 stops drive of the arm switches 116, 117 so that electrical continuity between the inverter high voltage unit 86 and the motor 61 is interrupted. Note that the flight control device 40 may also stop drive of the arm switches 116, 117 so that electrical continuity between the inverter high voltage unit 86 and the motor 61 is established.

[0097] In step S205, the flight control device 40 performs a discharge notification process. In the discharge notification process, a process is performed to notify that the residual power in the inverter high voltage unit 86 has been discharged. For example, in the discharge notification process, the pilot, external facilities, etc. are notified that the inverter high voltage unit 86 has been discharged by d-axis current application, or that the discharge of the inverter high voltage unit 86 has been completed.

[0098] According to the present embodiment described so far, when the control mode is the interlock mode, the flight control device 40 stops the application of drive voltage to the inverter high voltage unit 86 when the inverter lid 95 is opened. In this case, even if the inverter high voltage unit 86 is exposed through the inverter opening 92, it is possible to prevent a decrease in the safety of workers and the like. For example, when a worker performs maintenance or the like, simply opening the inverter lid 95 stops the application of drive voltage to the inverter high voltage unit 86. This prevents a worker from accidentally touching the inverter high voltage unit 86 with drive voltage still applied.

[0099] Furthermore, the flight control device 40 cancels the interlock mode when the eVTOL 10 is in flight. In this case, even if the inverter lid portion 95 is unintentionally opened, the power supply from the battery 31 to the motor 61 will not be cut off due to the interlock mode. This prevents the safety of the eVTOL 10 from being reduced due to a lack of propulsive force of the eVTOL 10 caused by the opening of the inverter lid portion 95.

[0100] Furthermore, when the eVTOL 10 is in flight, it is unlikely that an occupant such as a pilot will touch the propulsion device 100. Therefore, even if the inverter lid portion 95 is unintentionally opened, the risk of an occupant touching the inverter high-voltage portion 86 with the drive voltage applied is likely to be low. Therefore, when the eVTOL 10 is in flight, the overall safety of the occupants can be improved by prioritizing the prevention of a lack of propulsive force of the eVTOL 10 over the occupants touching the inverter high-voltage portion 86. In this way, setting and releasing the interlock mode can improve the safety of the eVTOL 10.

[0101] According to this embodiment, the flight control device 40 cancels the interlock mode by setting the control mode to the interlock release mode. In the interlock release mode, the power supply from the battery 31 to the motor 61 continues even if the inverter lid unit 95 is opened. Therefore, the interlock release mode can prevent the power supply from the battery 31 to the motor 61 from being unintentionally stopped when the inverter lid unit 95 is opened.

[0102] According to this embodiment, the flight control device 40 releases the interlock mode in conjunction with the takeoff of the eVTOL 10. This configuration avoids a situation in which the interlock mode is enabled while the eVTOL 10 is flying. In other words, it avoids a situation in which the control mode remains set to interlock mode even after the eVTOL 10 has taken off. This reliably prevents the power supply from the battery 31 to the motor 61 from being cut off due to unintentional opening of the inverter lid portion 95.

[0103] Furthermore, in the interlock mode, the power supply switch 132 is maintained in an energized state regardless of the detection signal from the lid detection circuit 120. Therefore, even if the lid detection circuit 120 malfunctions, the power supply from the battery 31 to the motor 61 is prevented from being cut off by the power supply switch 132.

[0104] According to this embodiment, the flight control device 40 sets the control mode to the interlock mode in conjunction with the landing of the eVTOL 10. This configuration avoids a situation in which the interlock mode is disabled after the eVTOL 10 lands. That is, it is possible to avoid a situation in which the control mode remains set to the interlock release mode even though the eVTOL 10 is not flying. This reliably prevents a situation in which a drive voltage remains applied to the inverter high-voltage unit 86 after the eVTOL 10 lands despite the pilot or other operator opening the inverter lid unit 95.

[0105] According to this embodiment, the flight control device 40 maintains the interlock mode when the eVTOL 10 is on the ground. In this case, it is possible to prevent the control mode from being set to the interlock mode when the eVTOL 10 is not flying, such as during maintenance of the eVTOL 10. This reliably prevents a situation in which a drive voltage remains applied to the inverter high-voltage unit 86 even though an operator opens the inverter lid unit 95 during maintenance, for example.

[0106] According to the present embodiment, the flight control device 40 discharges the inverter high voltage unit 86 when the control mode is in the interlock mode and the power supply from the battery 31 to the motor 61 is interrupted as a result of the opening of the inverter lid unit 95. With this configuration, when the inverter lid unit 95 is opened, it is possible to forcibly discharge the residual power of the inverter high voltage unit 86 in a shorter time than natural discharge. This reduces the risk that an operator will touch the inverter high voltage unit 86 while residual power remains in the inverter high voltage unit 86. Furthermore, this reduces the waiting time until the discharge of the inverter high voltage unit 86 is complete compared to natural discharge. Therefore, during maintenance of the eVTOL 10, it is possible to both improve the safety of the operator and reduce the work time, including the waiting time.

[0107] According to this embodiment, the flight control device 40 discharges the residual power of the inverter high voltage unit 86 to the motor 61. With this configuration, it is possible to discharge the inverter high voltage unit 86 without using a dedicated circuit for discharging the residual charge in the inverter high voltage unit 86. Therefore, it is not necessary to provide the propulsion device 100 with a dedicated circuit for discharging the inverter high voltage unit 86. Therefore, it is possible to improve the safety of the eVTOL 10 while avoiding an increase in the size of the propulsion device 100 due to the dedicated circuit.

[0108] According to this embodiment, the flight control device 40 energizes the d-axis of the motor 61, thereby discharging the residual power of the inverter high voltage unit 86 to the motor 61 so that the propeller 20 does not rotate. This configuration prevents the propeller 20 from rotating due to the residual power of the inverter high voltage unit 86, even when the power supply from the battery 31 to the motor 61 is cut off by the power feed switch 132. In other words, a configuration in which the propeller 20 does not rotate even when the motor 61 is driven can be achieved by driving the d-axis of the motor 61. This prevents the safety of the eVTOL 10 from being reduced due to the rotation of the propeller 20 caused by the discharge of the inverter high voltage unit 86.

[0109] For example, if the propeller 20 rotates in response to the discharge of the inverter high voltage unit 86, there is a concern that the rotation of the propeller 20 will generate lift, destabilizing the attitude of the eVTOL 10 and making it easier for an operator to come into contact with the rotating propeller 20. In contrast, in this embodiment, the propeller 20 does not rotate in response to the discharge of the inverter high voltage unit 86, thereby eliminating these concerns.

[0110] In this embodiment, when the inverter lid 95 is opened, the inverter low voltage section 87 as well as the inverter high voltage section 86 are exposed through the inverter opening 92. Therefore, there is a concern that when a worker performs maintenance on the inverter low voltage section 87, such as replacing electronic components, through the inverter opening 92, the worker may accidentally touch the inverter high voltage section 86. In response to this, according to this embodiment, in the interlock mode, the application of the drive voltage to the inverter high voltage section 86 is stopped when the inverter lid 95 is opened. Therefore, even if a worker accidentally touches the inverter high voltage section 86 while performing maintenance on the inverter low voltage section 87, no drive voltage is applied to the inverter high voltage section 86. Therefore, when the worker performs maintenance on the inverter low voltage section 87, the safety of the worker is prevented from being reduced by the inverter high voltage section 86.

[0111] Second Embodiment In the first embodiment, the residual power of the inverter high voltage section 86 is discharged to the motor 61. In contrast to this, in the second embodiment, the residual power of the inverter high voltage section 86 is discharged to a dedicated circuit. The configurations, actions, and effects of the second embodiment that are not specifically described are the same as those of the first embodiment. The second embodiment will be described mainly focusing on the differences from the first embodiment.

[0112] As shown in FIG. 7, the propulsion system 30 has a discharge circuit 141 and a first selection switch 142. The discharge circuit 141 is a circuit for discharging residual power in the inverter high voltage section 86. The discharge circuit 141 is formed including a resistor element, a capacitor element, etc. The discharge circuit 141 is a dedicated circuit for discharging the inverter high voltage section 86. The discharge circuit 141 is an electric circuit separate from the motor 61. The discharge circuit 141 is provided in the propulsion device 100. For example, the discharge circuit 141 is housed in the inverter housing 90. The discharge circuit 141 may also be provided independently of the propulsion device 100. In FIG. 7, the discharge circuit 141 is illustrated as DCH.

[0113] The discharge circuit 141 is electrically connected to the inverter high voltage unit 86. The discharge circuit 141 is electrically connected to the inverter high voltage unit 86 between the inverter high voltage unit 86 and the motor 61. That is, the discharge circuit 141 is electrically connected to the inverter circuit 85 between the inverter circuit 85 and the motor 61. The discharge circuit 141 is connected to a plurality of output lines 113. For example, the discharge circuit 141 is connected to a first line and a second line of the plurality of output lines 113 so as to enable electrical connection between the first line and the second line. The first line and the second line are different output lines 113. In the propulsion device 100, a discharge current flows from the inverter high voltage unit 86 to the discharge circuit 141, thereby discharging residual power in the inverter high voltage unit 86 to the discharge circuit 141.

[0114] The discharge circuit 141 is connected to the smoothing capacitor 114 via the inverter circuit 85. In the inverter high voltage unit 86, when the inverter circuit 85 is in a dischargeable state, the residual power of the smoothing capacitor 114 can be discharged to the motor 61 via the inverter circuit 85. The dischargeable state is a state in which the inverter circuit 85 connects the smoothing capacitor 114 and the motor 61 so that they can be electrically connected. For example, in the dischargeable state, both the upper arm switch 116 connected to one of the first line and the second line and the lower arm switch 117 connected to the other line are electrically connected. In this state, the residual power of the smoothing capacitor 114 is discharged to the motor 61 via the first line and the second line.

[0115] The discharge circuit 141 is configured so that the time required for the discharge circuit 141 to discharge the inverter high voltage unit 86 is shorter than the time required for the motor 61 to discharge the inverter high voltage unit 86. For example, the discharge circuit 141 is configured so that the discharge current flowing from the inverter high voltage unit 86 to the discharge circuit 141 is larger than the discharge current flowing from the inverter high voltage unit 86 to the motor 61. The time required for discharge by the discharge circuit 141 is shorter than the time required for discharge due to d-axis current application in the first embodiment. Note that the time required for discharge by the discharge circuit 141 may be shorter than the time required for discharge associated with rotation of the motor 61 in a fourth embodiment described below. Furthermore, the time required for discharge by the discharge circuit 141 may be shorter than the time required for discharge associated with rotation of the propeller 20 in a fifth embodiment described below.

[0116] First selection switch 142 is capable of cutting off the current flow between inverter high voltage unit 86 and motor 61. First selection switch 142 is provided between inverter high voltage unit 86 and motor 61. First selection switch 142 is provided on output line 113. For example, first selection switch 142 is capable of cutting off at least one of the first line and the second line.

[0117] The first selection switch 142 can selectively connect only one of the motor 61 and the discharge circuit 141 to the inverter high voltage section 86. The first selection switch 142 can be shifted between a first state and a second state. When in the first state, the first selection switch 142 electrically connects the motor 61 and the inverter high voltage section 86 while cutting off electrical continuity between the discharge circuit 141 and the inverter high voltage section 86. When in the second state, the first selection switch 142 electrically connects the discharge circuit 141 and the inverter high voltage section 86 while cutting off electrical continuity between the motor 61 and the inverter high voltage section 86. The first selection switch 142 is provided in the propulsion device 100. For example, the first selection switch 142 is housed in the inverter housing 90. The first selection switch 142 may also be provided independently of the propulsion device 100.

[0118] In the propulsion device 100, when the first selection switch 142 is in the second state, the residual power of the inverter high voltage unit 86 is discharged to the discharge circuit 141 via the first selection switch 142. Also, in the propulsion device 100, when the first selection switch 142 is in the second state and the inverter circuit 85 is in a dischargeable state, the residual power of the smoothing capacitor 114 is discharged to the discharge circuit 141 via the first selection switch 142 and the inverter circuit 85. The first selection switch 142 is sometimes referred to as a discharge switch for discharging the inverter high voltage unit 86.

[0119] The flight control device 40 performs the discharge control process in the same manner as in the first embodiment. In this embodiment, the discharge control process of the flight control process will be described with reference to the flowchart of FIG.

[0120] The flight control device 40 performs a circuit discharge process in step S301 shown in Figure 8. In the circuit discharge process, a process is performed to release residual power in the inverter high-voltage unit 86 to the discharge circuit 141. In the circuit discharge process, the flight control device 40 switches the first selection switch 142 to the second state and switches the inverter circuit 85 to a chargeable state. As a result, a discharge current flows from the inverter high-voltage unit 86 to the discharge circuit 141 via the first selection switch 142, thereby discharging the inverter high-voltage unit 86. In the inverter high-voltage unit 86, a discharge current flows from the smoothing capacitor 114 to the discharge circuit 141 via the inverter circuit 85 and the first selection switch 142, thereby discharging the smoothing capacitor 114. The function of the flight control device 40 that executes the process of step S301 corresponds to the circuit discharge unit.

[0121] After step S301, the flight control device 40 performs steps S202 and S203, similar to the first embodiment. However, in this embodiment, the count value of the discharge counter Cd indicates the duration of discharge of the inverter high voltage unit 86 due to the circuit discharge process. Furthermore, the counter threshold value TCd is a value indicating the upper limit of the duration of discharge due to the circuit discharge process, and is a value indicating the time required for the discharge of the inverter high voltage unit 86 due to the circuit discharge process to be completed.

[0122] When the discharge counter Cd reaches the counter threshold value TCd, the flight control device 40 determines that discharging of the inverter high voltage unit 86 is complete and proceeds to step S302. In step S302, the flight control device 40 performs a circuit de-energization process. In the circuit de-energization process, a process is performed to end the circuit discharge process. In the circuit de-energization process, the energizable connection between the inverter high voltage unit 86 and the discharge circuit 141 is cut off. For example, the flight control device 40 switches the first selection switch 142 to the first state. Note that in the circuit de-energization process, with the first selection switch 142 switched to the first state, the drive of the inverter circuit 85 may be stopped, similar to the d-axis drive stop process of the first embodiment described above.

[0123] After step S302, the flight control device 40 proceeds to step S205 and performs the discharge notification process, as in the first embodiment. In this discharge notification process, a notification is issued that the discharge circuit 141 has discharged the inverter high voltage unit 86.

[0124] According to this embodiment, the flight control device 40 discharges residual power in the inverter high voltage section 86 to the discharge circuit 141. In this configuration, the discharge circuit 141 is a dedicated circuit for discharge, and therefore the inverter high voltage section 86 can be discharged quickly. For example, the time required for the discharge circuit 141 to discharge the inverter high voltage section 86 can be made shorter than the time required for the motor 61 to discharge the inverter high voltage section 86. Therefore, the discharge circuit 141 can reduce the risk that an operator will touch the inverter high voltage section 86 while residual power remains in the inverter high voltage section 86 after the inverter lid 95 is opened.

[0125] Third Embodiment In the second embodiment, the discharge circuit 141 is connected between the motor 61 and the inverter circuit 85. In contrast, in the third embodiment, the discharge circuit 141 is connected between the inverter circuit 85 and the battery 31. The configurations, actions, and effects of the third embodiment that are not specifically described are the same as those of the second embodiment. The third embodiment will be described mainly focusing on the differences from the second embodiment.

[0126] 9 , the discharge circuit 141 is electrically connected to the inverter circuit 85 between the inverter circuit 85 and the battery 31. That is, the discharge circuit 141 is electrically connected to the inverter high voltage unit 86 between the inverter high voltage unit 86 and the battery 31. The discharge circuit 141 is connected to at least the P line 111 of the P line 111 and the N line 112. For example, the discharge circuit 141 is connected to the P line 111 and the N line 112 so as to enable electrical connection between the P line 111 and the N line 112. The discharge circuit 141 is connected between the smoothing capacitor 114 and the power supply switch 132.

[0127] In this embodiment, the propulsion system 30 has a second selection switch 143. The second selection switch 143 is capable of interrupting the flow of electricity between the battery 31 and the inverter high voltage unit 86. The second selection switch 143 is provided between the battery 31 and the inverter high voltage unit 86. The second selection switch 143 is provided on at least one of the P line 111 and the N line 112. For example, the second selection switch 143 is capable of interrupting both the P line 111 and the N line 112.

[0128] The second selection switch 143 can selectively connect only one of the battery 31 and the discharge circuit 141 to the inverter high voltage unit 86. When in a first state, the second selection switch 143 electrically connects the battery 31 and the inverter high voltage unit 86 while cutting off the electrical connection between the discharge circuit 141 and the inverter high voltage unit 86. When in a second state, the second selection switch 143 electrically connects the discharge circuit 141 and the inverter high voltage unit 86 while cutting off the electrical connection between the battery 31 and the inverter high voltage unit 86.

[0129] In the propulsion device 100, when the second selection switch 143 is in the second state, the residual power of the inverter high voltage unit 86 is discharged to the discharge circuit 141 via the second selection switch 143. In this case, the residual power of the smoothing capacitor 114 is also discharged to the discharge circuit 141 via the second selection switch 143. In this embodiment, the discharge circuit 141 is electrically connected to the smoothing capacitor 114 without passing through the inverter circuit 85, so that a discharge current flows from the smoothing capacitor 114 to the discharge circuit 141 regardless of whether the inverter circuit 85 is in a dischargeable state. The second selection switch 143 is sometimes referred to as a discharge switch for discharging the inverter high voltage unit 86.

[0130] In this embodiment, a discharge control process is performed in the same manner as in the second embodiment. For example, the flight control device 40 performs a circuit discharge process in step S301 of the discharge control process, in the same manner as in the second embodiment. In the circuit discharge process, the flight control device 40 switches the second selection switch 143 to the second state. As a result, a discharge current flows from the inverter high-voltage unit 86 to the discharge circuit 141 via the second selection switch 143, thereby discharging the inverter high-voltage unit 86. In the inverter high-voltage unit 86, a discharge current flows from the smoothing capacitor 114 to the discharge circuit 141 via the second selection switch 143, thereby discharging the smoothing capacitor 114. In the inverter high-voltage unit 86, a charging current flows from the smoothing capacitor 114 to the discharge circuit 141 without passing through the inverter circuit 85, so the flight control device 40 does not need to transition the inverter circuit 85 to a dischargeable state when discharging the inverter high-voltage unit 86.

[0131] In this embodiment, the second selection switch 143 may be connected between the power supply switch 132 and the battery 31. In this configuration, when the discharge circuit 141 discharges the inverter high voltage section 86, the flight control device 40 needs to switch the second selection switch 143 to the second state and also to place the power supply switch 132 in the conducting state.

[0132] <Fourth embodiment> In the first embodiment, the inverter high voltage section 86 is discharged by driving the d-axis of the motor 61 so that the motor rotor 63 does not rotate. In contrast, in the fourth embodiment, the inverter high voltage section 86 is discharged by driving the motor 61 so that the motor rotor 63 rotates. The configurations, actions, and effects not specifically described in the fourth embodiment are the same as those in the first embodiment. In the third embodiment, the differences from the first embodiment will be mainly described.

[0133] As shown in Fig. 10, the propulsion system 30 has a clutch 145. The clutch 145 can block the transmission of rotation of the motor rotor 63 to the propeller 20. The clutch 145 is provided between the motor rotor 63 and the propeller 20. For example, the clutch 145 is provided between the motor shaft and the propeller shaft. The clutch 145 is formed to include a one-way clutch, an electromagnetic clutch, or the like.

[0134] The clutch 145 can be switched between a transmission state and a disengagement state. When the clutch 145 is in the transmission state, the torque of the motor 61 is transmitted to the propeller 20. In this case, the torque of the motor 61 causes the propeller 20 to rotate. When the clutch 145 is in the disengagement state, the torque of the motor 61 is not transmitted to the propeller 20. In this case, the propeller 20 does not rotate even if the motor 61 is driven to rotate. In other words, the motor 61 rotates freely relative to the propeller 20.

[0135] In this embodiment, the discharge control process will be described with reference to the flowchart of FIG.

[0136] The flight control device 40 performs motor idle processing in steps S401 and S402 shown in Figure 11. In motor idle processing, the motor 61 is caused to idle relative to the propeller 20, thereby discharging residual power from the inverter high voltage unit 86 to the motor 61. In motor idle processing, even if the motor 61 is driven to rotate, the propeller 20 does not rotate. The functions in the flight control device 40 that execute the processing of steps S401 and S402 correspond to the motor discharge unit and the stop discharge unit.

[0137] The flight control device 40 performs a propeller disconnection process in step S401 of the motor idle process. The propeller disconnection process is a process for preventing the rotation of the motor 61 from being transmitted to the propeller 20. For example, the flight control device 40 transitions the clutch 145 to a disconnected state.

[0138] In step S402, the flight control device 40 performs a rotational drive process. In the rotational drive process, a process for rotationally driving the motor 61 is performed in the same way as when the motor 61 is driven to fly the eVTOL 10. For example, in the rotational drive process, unlike the d-axis drive process of the first embodiment described above, motor control is performed so as to generate torque for rotating the motor rotor 63. For example, the flight control device 40 outputs both a d-axis current and a q-axis current so as to rotate the motor rotor 63. In the motor idling process, because the clutch 145 is in a disengaged state, the propeller 20 does not rotate even if the motor 61 is rotationally driven by the residual power of the inverter high-voltage unit 86.

[0139] After step S402, the flight control device 40 performs steps S202 and S203, as in the first embodiment. However, in this embodiment, the count value of the discharge counter Cd indicates the duration of discharge of the inverter high voltage unit 86 due to the motor idle process. Furthermore, the counter threshold value TCd is a value indicating the upper limit of the duration of discharge due to the motor idle process, and is a value indicating the time required for the discharge of the inverter high voltage unit 86 due to the motor idle process to be completed.

[0140] When the discharge counter Cd reaches the counter threshold value TCd, the flight control device 40 determines that the discharge of the inverter high voltage unit 86 is complete and proceeds to step S403. In step S403, the flight control device 40 performs a rotational drive stop process. In the rotational drive stop process, a process for stopping the rotational drive process is performed. For example, in the rotational drive stop process, a process similar to the d-axis drive stop process in the first embodiment is performed. The rotational drive stop process is also a process for stopping the motor idle process.

[0141] In step S404, the flight control device 40 performs propeller transmission processing. In the propeller transmission processing, when the motor 61 is driven to rotate, processing is performed to transmit the rotation of the motor 61 to the propeller 20. For example, the flight control device 40 transitions the clutch 145 to a transmission state.

[0142] After step S404, the flight control device 40 proceeds to step S205 and performs the discharge notification process, as in the first embodiment. In this discharge notification process, it is notified that the inverter high voltage unit 86 has been discharged due to the motor idling process or the rotation drive process.

[0143] According to this embodiment, the flight control device 40 causes the motor 61 to idle relative to the propeller 20, thereby discharging the residual power of the inverter high voltage unit 86 to the motor 61 so that the propeller 20 does not rotate. As with the first embodiment, this configuration prevents the propeller 20 from rotating due to the residual power of the inverter high voltage unit 86 even when the power supply from the battery 31 to the motor 61 is cut off by the power feed switch 132. In other words, the clutch 145 can realize a configuration in which the propeller 20 does not rotate even when the motor 61 is driven to rotate.

[0144] Fifth Embodiment In the first embodiment, the inverter high voltage section 86 discharges electricity so that the propeller 20 does not rotate. In contrast, in the fifth embodiment, the inverter high voltage section 86 discharges electricity so that the propeller 20 rotates. The configurations, actions, and effects of the fifth embodiment that are not specifically described are the same as those of the first embodiment. The fifth embodiment will be described mainly focusing on the differences from the first embodiment.

[0145] In this embodiment, the discharge control process will be described with reference to the flowchart of FIG.

[0146] The flight control device 40 performs propeller rotation processing in step S501 shown in Figure 12. In the propeller rotation processing, processing is performed to rotationally drive the motor 61 so as to rotate the propeller 20. For example, in a configuration in which the propulsion system 30 has a clutch 145 as in the fourth embodiment, the flight control device 40 rotationally drives the motor 61 while keeping the clutch 145 in a transmission state. In the propeller rotation processing, the flight control device 40 performs motor control so as to generate torque to rotate the motor rotor 63, as in the rotational drive processing of the fourth embodiment. The functions of the flight control device 40 that execute the processing of step S501 correspond to the motor discharge unit and the rotation discharge unit.

[0147] In step S502, the flight control device 40 determines whether the attitude of the eVTOL 10 is stable while the eVTOL 10 is on the ground. When the propeller 20 is rotating due to the residual power of the inverter high voltage unit 86, the rotation of the propeller 20 is likely to generate lift on the eVTOL 10. When the rotation speed of the motor 61 increases and the lift of the eVTOL 10 becomes large to a certain extent, the attitude of the eVTOL 10 is likely to become unstable. Examples of cases where the attitude of the eVTOL 10 becomes unstable include when the attitude of the eVTOL 10 changes so that the eVTOL 10 sways in the roll direction, pitch direction, or yaw direction.

[0148] The flight control device 40 uses the eVTOL information to determine whether the attitude of the eVTOL 10 is stable. For example, the propulsion system 30 has an attitude sensor that detects the attitude of the eVTOL 10. The attitude sensor is provided in the eVTOL 10 and outputs a detection signal to the flight control device 40. The attitude sensor is formed by including a speed sensor, a gyro sensor, an altitude sensor, etc. The flight control device 40 acquires the detection signal of the attitude sensor as eVTOL information. The flight control device 40 uses the detection result of the attitude sensor to determine whether the attitude of the eVTOL 10 is stable.

[0149] When the attitude of the eVTOL 10 is stable, the flight control device 40 performs the processes of steps S202 and S203, as in the first embodiment. However, in this embodiment, the count value of the discharge counter Cd indicates the duration of discharge of the inverter high voltage unit 86 due to the propeller rotation process. Furthermore, the counter threshold value TCd is a value indicating the upper limit of the duration of discharge due to the propeller rotation process, and is a value indicating the time required for the discharge of the inverter high voltage unit 86 due to the propeller rotation process to be completed.

[0150] When the discharge counter Cd reaches the counter threshold value TCd, the flight control device 40 determines that the discharge of the inverter high voltage unit 86 is complete, and proceeds to step S503. In step S403, the flight control device 40 performs propeller stop processing. In the propeller stop processing, processing for stopping the propeller rotation processing is performed. For example, in the propeller stop processing, processing similar to the d-axis drive stop processing in the first embodiment is performed. The propeller stop processing is also processing for stopping the rotation drive of the motor 61.

[0151] After step S503, the flight control device 40 proceeds to step S205 and performs the discharge notification process, as in the first embodiment. In this discharge notification process, it is notified that the inverter high voltage unit 86 has been discharged due to the propeller rotation process.

[0152] If the attitude of the eVTOL 10 is not stable, the flight control device 40 proceeds to step S504. In step S504, the flight control device 40 performs a rotation reduction process. In the rotation reduction process, processing is performed to reduce the rotation speed of the propeller 20. The flight control device 40 controls the inverter circuit 85 so that the rotation speed of the propeller 20 is reduced to an extent that the attitude of the eVTOL 10 on the ground is stable. For example, the flight control device 40 performs motor control so that the rotation of the motor 61 and the propeller 20 is reduced by setting the required torque to a small value that is sufficient to stabilize the attitude of the eVTOL 10.

[0153] According to this embodiment, flight control device 40 discharges the residual power of inverter high voltage unit 86 to motor 61 so as to rotate propeller 20. In this configuration, propeller 20 rotates even though the power supply from battery 31 to motor 61 is cut off by power feed switch 132, allowing an operator such as a pilot to visually notice that inverter high voltage unit 86 is discharging. This prevents an operator from touching inverter high voltage unit 86 when the inverter cover 95 has been opened and discharging of inverter high voltage unit 86 has not yet been completed.

[0154] Furthermore, in this configuration, the residual power of the inverter high voltage unit 86 rotates the propeller 20 together with the motor 61. Therefore, consumption of the residual power is more likely to increase compared to the configuration in which the propeller 20 is not rotated, as in the fourth embodiment. Therefore, the time required for the inverter high voltage unit 86 to complete discharge can be shortened by the rotation of the propeller 20.

[0155] Sixth Embodiment In the sixth embodiment, the inverter high voltage section 86 discharges when the power supply from the battery 31 to the motor 61 is cut off, regardless of whether the inverter lid section 95 is open or closed. The configurations, actions, and effects not specifically described in the sixth embodiment are the same as those in the first embodiment. The sixth embodiment will be described mainly focusing on the differences from the first embodiment.

[0156] The flight control device 40 performs flight control processing in the same manner as in the first embodiment. In this embodiment, the flight control processing will be described with reference to the flowchart of FIG.

[0157] In step S601 shown in Fig. 13, the flight control device 40 acquires eVTOL information, similar to step S101 in the first embodiment. In step S602, the flight control device 40 determines whether to power off the eVTOL 10. The flight control device 40 uses the eVTOL information to determine whether to power off the eVTOL 10. For example, the flight control device 40 determines whether to power off the eVTOL 10 in response to an input operation by the pilot, an input signal from an external facility, or the like.

[0158] For example, the flight control device 40 determines whether to turn off the main switch of the eVTOL 10. When turning off the main switch, the flight control device 40 determines to power off the eVTOL 10. The main switch is a power switch for the eVTOL 10, and is a switch for turning on and off the power of the eVTOL 10. The power of the propulsion system 30 is turned on and off by the main switch, along with the power of the eVTOL 10. The main switch can cut off the power supply from the battery 31 to the propulsion device 100, the communication unit 34, and the flight control device 40. Note that the main switch may include a power supply switch 132.

[0159] When powering off the eVTOL 10, the flight control device 40 proceeds to step S613. The flight control device 40 performs power-off processing in step S613. In the power-off processing, processing is performed to turn off the power of the eVTOL 10. For example, the flight control device 40 switches the main switch to the OFF state. In the power-off processing, the power supply switch 132 is also switched to the OFF state. When the main switch is switched to the OFF state, residual power may remain in the inverter high-voltage unit 86, just as in the case when the power supply switch 132 is switched to the OFF state in the interlock mode in the first embodiment described above.

[0160] Therefore, the flight control device 40 performs off-discharge processing in step S614. In the off-discharge processing, processing is performed to discharge the inverter high voltage unit 86. The flight control device 40 performs processing to discharge the residual power of the inverter high voltage unit 86 to the motor 61. In the off-discharge processing, the discharge control processing of the first, fourth, and fifth embodiments is performed. For example, in the off-discharge processing, the d-axis drive processing of step S201, the rotation drive processing of step S402, and the propeller rotation processing of step S501 are performed. The function of the flight control device 40 that executes the processing of step S614 corresponds to the off-discharge unit.

[0161] If the eVTOL 10 is not to be powered off, the flight control device 40 proceeds to step S603. In step S603, the flight control device 40 determines whether the eVTOL 10 is in flight. This determination is made using the eVTOL information.

[0162] If the eVTOL 10 is in flight, the flight control device 40 proceeds to step S604. In step S604, the flight control device 40 sets the control mode to interlock release mode. For example, if the control mode is interlock mode, the flight control device 40 switches the control mode from interlock mode to interlock release mode. Also, if the control mode is already in interlock release mode, the flight control device 40 maintains the control mode in interlock release mode. The function in the flight control device 40 that executes the processing of step S604 corresponds to the interlock release unit.

[0163] In step S605, the flight control device 40 determines whether the eVTOL 10 and an obstacle come abnormally close together. Obstacles that may occur when the eVTOL 10 is flying include other aircraft in flight and tall buildings. The other aircraft is a flying object different from the eVTOL 10. The eVTOL 10 and an obstacle may come abnormally close together when there is a high possibility that the eVTOL 10 will come into contact with or collide with the obstacle, or when the flight control device 40 detects contact or collision between the eVTOL 10 and the other aircraft. A situation in which the eVTOL 10 comes abnormally close together with an obstacle during flight constitutes an emergency situation for the eVTOL 10.

[0164] If the eVTOL 10 comes abnormally close to an obstacle while flying, the flight control device 40 proceeds to step S606. In step S606, the flight control device 40 performs forced shutdown processing. The forced shutdown processing is processing for forcibly cutting off the power supply from the battery 31 to the motor 61. The forced shutdown processing includes processing for switching the main switch to the OFF state and processing for switching the power supply switch 132 to the shutdown state. In the forced shutdown processing, the power supply from the battery 31 to the motor 61 is cut off for at least one of the multiple propulsion devices 100.

[0165] In step S607, the flight control device 40 performs forced discharge processing. In forced discharge processing, processing is performed to discharge residual power in the inverter high voltage unit 86. The flight control device 40 performs forced discharge processing so that the time required for discharging the inverter high voltage unit 86 through forced discharge processing is shorter than the time required for discharging the inverter high voltage unit 86 through the off discharge unit. In forced discharge processing, residual power in the inverter high voltage unit 86 is discharged more rapidly than when the inverter high voltage unit 86 is discharged through the off discharge unit. In forced discharge processing, the discharge control processing of the second embodiment described above is performed, etc. For example, in forced discharge processing, the circuit discharge processing of step S301 described above is performed. In this embodiment, as in the second embodiment described above, the propulsion system 30 has a discharge circuit 141.

[0166] In step S605, if the eVTOL 10 does not abnormally approach an obstacle, the flight control device 40 ends this flight control process.

[0167] If the eVTOL 10 is not in flight in step S603, the flight control device 40 determines that the eVTOL 10 is on the ground and proceeds to step S608. In step S608, the flight control device 40 sets the control mode to interlock mode. For example, if the control mode is in interlock release mode, the flight control device 40 switches the control mode from interlock release mode to interlock mode. Also, if the control mode is already in interlock mode, the flight control device 40 maintains the control mode in interlock mode. The function in the flight control device 40 that executes the processing of step S608 corresponds to the interlock unit.

[0168] In step S609, the flight control device 40 determines whether the inverter lid portion 95 is in the open state, similar to step 105 in the first embodiment. A situation in which the inverter lid portion 95 is open in interlock mode while the eVTOL 10 is on the ground corresponds to an emergency situation for the eVTOL 10.

[0169] If the inverter lid portion 95 is not in the open state, the flight control device 40 proceeds to step S610. As in step S610, the flight control device 40 determines whether the eVTOL 10 and an obstacle will come abnormally close together. Obstacles when the eVTOL 10 is on the ground include other aircraft on the ground, other aircraft flying at low altitude, and buildings. When both the eVTOL 10 and the other aircraft are on the ground, the eVTOL 10 and the other aircraft may come abnormally close together due to at least one of the eVTOL 10 and the other aircraft moving on the ground. A situation in which the eVTOL 10 on the ground comes abnormally close to an obstacle constitutes an emergency situation for the eVTOL 10.

[0170] If the eVTOL 10 comes abnormally close to an obstacle while on the ground, the flight control device 40 performs the processes of steps S606 and S607, similar to when the eVTOL 10 comes abnormally close to an obstacle while in flight. In this case, the flight control device 40 performs forced shutoff processing and forced discharge processing. On the other hand, if the inverter lid unit 95 is not in the open state while the eVTOL 10 is on the ground and the eVTOL 10 does not come abnormally close to an obstacle, the flight control device 40 simply ends this flight control processing.

[0171] If the inverter cover 95 is in the open state in step S609, the flight control device 40 proceeds to step S611. In step S611, the flight control device 40 performs the interlock cutoff process, similar to step S106 in the first embodiment.

[0172] In step S612, the flight control device 40 performs interlock discharge processing. In the interlock discharge processing, processing is performed to discharge residual power from the inverter high voltage unit 86. The function of the flight control device 40 that executes the processing of step S612 corresponds to the discharge execution unit.

[0173] The flight control device 40 performs interlock discharge processing so that the time required for discharging the inverter high voltage unit 86 through the interlock discharge processing is shorter than the time required for discharging the inverter high voltage unit 86 through the off discharge unit. In the interlock discharge processing, the residual power of the inverter high voltage unit 86 is discharged more rapidly than when the inverter high voltage unit 86 is discharged through the off discharge unit. In the interlock discharge processing, the discharge control processing of the second embodiment described above is performed. For example, in the interlock discharge processing, the circuit discharge processing of step S301 described above is performed. The function of the flight control device 40 that executes the processing of step S612 corresponds to the interlock discharge unit.

[0174] In inverter device 80, the larger the discharge current flowing from inverter high voltage unit 86 to discharge circuit 141, the shorter the time required for inverter high voltage unit 86 to discharge. On the other hand, there is a concern that the larger the discharge current flowing from inverter high voltage unit 86 to discharge circuit 141, the more likely the discharge capacity of discharge circuit 141 will decrease due to progressive deterioration. For example, it is thought that the more frequently discharges inverter high voltage unit 86 by discharge circuit 141, the more likely the discharge capacity of discharge circuit 141 will decrease. In other words, the discharge capacity of discharge devices and the like that form discharge circuit 141 is more likely to decrease.

[0175] In contrast, according to the present embodiment, when the eVTOL 10 is powered off, the inverter high voltage unit 86 is discharged by off-discharge processing. In this case, the inverter high voltage unit 86 is discharged more slowly than the inverter high voltage unit 86 is rapidly discharged by interlock discharge processing. In off-discharge processing, the inverter high voltage unit 86 is discharged by the motor 61, and the discharge current flowing to the motor 61 is limited by motor control. Therefore, the discharge current flowing to the motor 61 is unlikely to become excessive, and the discharge current is unlikely to cause deterioration of the motor 61. Furthermore, in off-discharge processing, there is no need to use the discharge circuit 141 to discharge the inverter high voltage unit 86, and therefore the frequency with which the discharge circuit 141 is used to discharge the inverter high voltage unit 86 can be reduced. This makes it possible to suppress a decrease in the discharge capacity of a discharge device or the like.

[0176] In this embodiment, if the eVTOL 10 comes abnormally close to an obstacle while the eVTOL 10 is flying or on the ground, the power supply from the battery 31 to the motor 61 is cut off by forced cut-off processing. In this case, it is possible to prevent an abnormality from occurring in the eVTOL 10 due to power being supplied from the battery 31 to the motor 61 when the eVTOL 10 comes abnormally close to an obstacle. Also, in this case, the inverter high-voltage unit 86 is rapidly discharged by forced discharge processing. Therefore, it is possible to prevent an abnormality from occurring in the eVTOL 10 due to residual power remaining in the inverter high-voltage unit 86 when the eVTOL 10 comes close to an obstacle.

[0177] Seventh Embodiment In the seventh embodiment, the arm switches 116 and 117 are switched so that the residual power of the smoothing capacitor 114 is discharged to the inverter circuit 85. The configurations, actions, and effects of the seventh embodiment that are not particularly described are the same as those of the first embodiment. The seventh embodiment will be described mainly focusing on the differences from the first embodiment.

[0178] As shown in FIG. 15 , the inverter device 80 has an upper switch component 116P and a lower switch component 117P. The upper switch component 116P is a semiconductor component that forms the upper arm switch 116. The lower switch component 117P is a semiconductor component that forms the lower arm switch 117. The switch components 116P and 117P have switch protection units (not shown). The switch protection units protect the arm switches 116 and 117. The switch protection units are packages made of a resin material or the like, and cover the arm switches 116 and 117.

[0179] The upper switch component 116P includes an upper diode 116a and an upper parasitic capacitance 116b. The lower switch component 117P includes a lower diode 117a and a lower parasitic capacitance 117b. The diodes 116a and 117a and the parasitic capacitances 116b and 117b are included in the inverter circuit 85. The diodes 116a and 117a and the parasitic capacitances 116b and 117b are included in the upper and lower arm circuits 115 in each of the multiple phases.

[0180] The diodes 116a and 117a are freewheeling diodes and are connected in anti-parallel to the arm switches 116 and 117. The diodes 116a and 117a are freewheeling diodes of the arm switches 116 and 117. The switch components 116P and 117P may include freewheeling diodes. In this case, the diodes 116a and 117a are parasitic diodes that are originally included in the switch components, separate from the freewheeling diodes.

[0181] The upper parasitic capacitance 116b is the parasitic capacitance of the upper arm switch 116. The lower parasitic capacitance 117b is the parasitic capacitance of the lower arm switch 117. In the switch components 116P and 117P, the parasitic capacitances 116b and 117b exist in a state where they are connected in parallel to the arm switches 116 and 117. The parasitic capacitances 116b and 117b are, for example, about 100 nF. The parasitic capacitances 116b and 117b are portions of the switch components 116P and 117P that act as capacitors.

[0182] The arm switches 116 and 117 can be switched between an ON state and an OFF state. The ON state is a state in which current can be passed through the arm switches 116 and 117. The ON state corresponds to a current-carrying state. The OFF state is a state in which current is cut off from the arm switches 116 and 117. The OFF state corresponds to a cut-off state.

[0183] The eVTOL 10 is provided with a plurality of batteries 31. In the propulsion system 30, power is supplied to the first inverter device 801 and power is supplied to the second inverter device 802 by separate batteries 31. The plurality of batteries 31 include a first battery 31a and a second battery 31b. The batteries 31a and 31b are included in the propulsion system 30. The first battery 31a is electrically connected to the first inverter device 801. The first battery 31a is capable of supplying power to the first inverter device 801. The second battery 31b is electrically connected to the second inverter device 802. The second battery 31b is capable of supplying power to the second inverter device 802.

[0184] The eVTOL 10 is provided with a plurality of power feed switches 132. The plurality of power feed switches 132 include a first power feed switch 132a and a second power feed switch 132b. The power feed switches 132a and 132b are included in the propulsion system 30. The first power feed switch 132a can cut off the power supply from the first battery 31a to the first inverter device 801. The second power feed switch 132b can cut off the power supply from the second battery 31b to the second inverter device 802.

[0185] The propulsion system 30 has a first battery voltage sensor 151a, a second battery voltage sensor 151b, a capacitor voltage sensor 152, and an inverter temperature sensor 153. The voltage sensors 151a, 151b, and 152 are included in various sensors. The first battery voltage sensor 151a is a sensor that detects the voltage of the first battery 31a. The second battery voltage sensor 151b is a sensor that detects the voltage of the second battery 31b. The battery voltage sensors 151a and 151b are communicatively connected to the flight control device 40. The battery voltage sensors 151a and 151b output detection signals corresponding to the voltages of the batteries 31a and 31b to the flight control device 40. The battery voltage sensors 151a and 151b may output the detection signals to the inverter control unit 81.

[0186] The capacitor voltage sensor 152 is a sensor that detects the voltage of the smoothing capacitor 114. The capacitor voltage sensor 152 is included in the inverter device 80. The capacitor voltage sensor 152 is communicatively connected to the inverter control unit 81. The capacitor voltage sensor 152 outputs a detection signal corresponding to the voltage of the smoothing capacitor 114 to the inverter control unit 81. The detection signal of the capacitor voltage sensor 152 is input to the flight control device 40 via the inverter control unit 81. The capacitor voltage sensor 152 is provided in each of the first inverter device 801 and the second inverter device 802.

[0187] The inverter temperature sensor 153 is a sensor that detects the temperature of the inverter device 80. The inverter temperature sensor 153 is included in the inverter device 80. The inverter temperature sensor 153 is communicatively connected to the inverter control unit 81. The inverter temperature sensor 153 outputs a detection signal corresponding to the temperature of the inverter device 80 to the inverter control unit 81. The detection signal of the inverter temperature sensor 153 is input to the flight control device 40 via the inverter control unit 81.

[0188] The inverter temperature sensor 153 is housed in the inverter housing 90. The inverter temperature sensor 153 can detect the internal temperature of the inverter housing 90. For example, the inverter temperature sensor 153 can detect the temperature of the inverter high-voltage section 86 and the temperature of the inverter low-voltage section 87. The temperature of the inverter high-voltage section 86 includes the temperature of the upper switch component 116P, the temperature of the lower switch component 117P, and the temperature of the inverter circuit 85. When the temperatures of the switch components 116P and 117P are high, the temperature detected by the inverter temperature sensor 153 is likely to be high.

[0189] In this embodiment, the discharge control process will be described with reference to the flowchart in Fig. 16. The discharge control process is a process performed on the inverter device 80. The flight control device 40 performs the discharge control process separately for each of the first inverter device 801 and the second inverter device 802. For example, the flight control device 40 executes the discharge control process for the first inverter device 801 and the discharge control process for the second inverter device 802 in synchronization with each other.

[0190] In step S701 shown in FIG. 16, the flight control device 40 determines whether the up / down counter Ca is a value equal to n times 2, where n is an integer. The flight control device 40 determines whether the up / down counter Ca is an even number. The up / down counter Ca is a counter that indicates the total number of times the up-on process has been completed and the number of times the down-on process has been completed. The up-on process and the down-on process will be described later. If the up / down counter Ca is an even number, the flight control device 40 proceeds to step S702.

[0191] In step S702, the flight control device 40 performs an upper-on process. The upper-on process is a process for putting the inverter circuit 85 into the upper-on state. The upper-on process includes a process for transitioning the inverter circuit 85 to the upper-on state and a process for maintaining the inverter circuit 85 in the upper-on state. In the upper-on state, the upper arm switches 116 are in the on state while the lower arm switches 117 are in the off state for all of the multiple phases. The upper-on state corresponds to the upper energized state.

[0192] 17, when the inverter circuit 85 is in the high-side on state, a first high-side on-current IH1 and a second high-side on-current IH2 flow through the inverter device 80. The first high-side on-current IH1 is a discharge current for discharging the residual power of the smoothing capacitor 114 to the inverter circuit 85. Discharging the residual power of the smoothing capacitor 114 to the inverter circuit 85 is sometimes referred to as intra-inverter discharging.

[0193] The first upper on-current IH1 flows from the smoothing capacitor 114 through the upper arm switch 116 to the lower parasitic capacitance 117b. The residual power of the smoothing capacitor 114 is supplied to the lower parasitic capacitance 117b by the first upper on-current IH1 and is stored in the lower parasitic capacitance 117b. In the upper on-processing, the lower parasitic capacitance 117b is charged with the residual power of the smoothing capacitor 114. That is, in the upper on-processing, the residual charge of the smoothing capacitor 114 moves to the lower parasitic capacitance 117b.

[0194] The second upper on-current IH2 is a discharge current that discharges the power stored in the upper parasitic capacitance 116b to the upper arm switch 116. The second upper on-current IH2 flows in a circulating manner between the upper arm switch 116 and the upper parasitic capacitance 116b. In the upper switch component 116P, the power of the upper parasitic capacitance 116b is consumed by the internal resistance of the upper arm switch 116 and the internal resistance of the upper switch component 116P, and as a result, the power of the upper parasitic capacitance 116b is discharged to the upper arm switch 116. As will be described later, when the inverter circuit 85 is in the lower on-state, the residual power of the smoothing capacitor 114 is stored in the upper parasitic capacitance 116b by the first lower on-current IL1.

[0195] Returning to FIG. 16, in step S703, the flight control device 40 measures the upper-on time TH. The upper-on time TH is the duration for which the upper-on process continues. The upper-on time TH is also the elapsed time after the inverter circuit 85 transitions to the upper-on state. As the upper-on time TH increases, the amount of charge stored in the lower parasitic capacitance 117b increases due to the first upper-on current IH1, and the lower parasitic voltage VdsL (see FIG. 19) increases. The lower parasitic voltage VdsL is the voltage of the lower parasitic capacitance 117b. As the upper-on process continues, the lower parasitic voltage VdsL reaches a lower peak voltage VdsLp. The lower peak voltage VdsLp is a value determined by the amount of residual power in the smoothing capacitor 114, the size of the lower parasitic capacitance 117b, and other factors. The lower peak voltage VdsLp is the maximum value of the lower parasitic voltage VdsL during the period for which the upper-on process continues. During the period in which the top-side ON process continues, the bottom-side parasitic voltage VdsL reaches the bottom-side peak voltage VdsLp and is then maintained at the bottom-side peak voltage VdsLp.

[0196] In step S704, the flight control device 40 determines whether the upper on-time TH has reached the upper on-threshold JTH. The upper on-threshold JTH is a value determined in advance through testing or the like and is stored in the memory 43 or the like. The upper on-threshold JTH is set to, for example, 50 μsec. The upper on-threshold JTH is a value indicating the upper limit of the upper on-time TH. The upper on-threshold JTH is set to a value indicating a time longer than the time required for the lower parasitic voltage VdsL to reach the lower peak voltage VdsLp.

[0197] If the upper on-time TH has not reached the upper on-threshold JTH, the flight control device 40 continues the current upper on-processing and ends the discharge control process. In this case, the flight control device 40 executes steps S701 to S704 in the next discharge control process. The flight control device 40 repeatedly executes steps S701 to S704 until the upper on-time TH reaches the upper on-threshold JTH. In steps S702 to S704, the flight control device 40 maintains the inverter circuit 85 in the upper on state so that the residual power of the smoothing capacitor 114 is stored in the lower parasitic capacitance 117b and the power of the lower parasitic capacitance 117b is discharged to the lower arm switch 117. The function of the flight control device 40 that executes steps S702 to S704 corresponds to the upper maintaining unit.

[0198] If the upper on-time TH reaches the upper on-threshold JTH, the flight control device 40 determines that this upper on-processing is complete and proceeds to step S708. In step S708, the flight control device 40 counts the up / down counter Ca. The up / down counter Ca counts the number of times the smoothing capacitor 114 has been discharged by the upper on-processing.

[0199] The flight control device 40 adds a predetermined additional value to the up / down counter Ca. For example, the flight control device 40 sets the additional value to 1 and increments the up / down counter Ca by 1. The up / down counter Ca is set in the memory 43 or the like. If the up / down counter Ca is an even number and the up / down ON process has been executed, the up / down counter Ca becomes an odd number after being counted. Furthermore, if the up / down ON time TH reaches the up / down ON threshold JTH, the flight control device 40 resets the up / down ON time TH to zero.

[0200] In step S709, the flight control device 40 determines whether the up / down counter Ca has reached the up / down counter threshold TCa. The up / down counter threshold TCa is a value determined in advance through testing or the like, and is stored in the memory 43 or the like. The up / down counter threshold TCa is a value indicating the number of times the up-ON process and the down-ON process are executed. The larger the up / down counter threshold TCa, the more times the up-ON process and the down-ON process are executed. The up / down counter threshold TCa sets the length of the period during which the smoothing capacitor 114 continues to discharge due to the up-ON process and the down-ON process.

[0201] If the up / down counter Ca has not reached the up / down counter threshold TCa, the flight control device 40 ends the discharge control process. In this case, the flight control device 40 executes the process of step S701 in the next discharge control process.

[0202] If the up / down counter Ca is not an even number in step S701, the flight control device 40 proceeds to step S705 and performs a lower-side ON process. The lower-side ON process is a process for setting the inverter circuit 85 to the lower-side ON state. The lower-side ON process includes a process for transitioning the inverter circuit 85 to the lower-side ON state and a process for maintaining the inverter circuit 85 in the lower-side ON state. In the lower-side ON state, the lower arm switches 117 are in the ON state while the upper arm switches 116 are in the OFF state for all of the multiple phases. The lower-side ON state corresponds to a lower-side energized state.

[0203] 18, when the inverter circuit 85 is in the low on state, a first low on current IL1 and a second low on current IL2 flow through the inverter device 80. The first low on current IL1 is a discharge current for discharging the residual power of the smoothing capacitor 114 to the inverter circuit 85.

[0204] The first lower on-current IL1 flows from the smoothing capacitor 114 to the upper parasitic capacitance 116b through the lower arm switch 117. The residual power of the smoothing capacitor 114 is supplied to the upper parasitic capacitance 116b by the first lower on-current IL1 and is stored in the upper parasitic capacitance 116b. In the lower on-processing, the upper parasitic capacitance is charged by the residual power of the smoothing capacitor 114. That is, in the lower on-processing, the residual charge of the smoothing capacitor 114 moves to the upper parasitic capacitance 116b.

[0205] The second lower on-current IL2 is a discharge current that discharges the power stored in the lower parasitic capacitance 117b to the lower arm switch 117. The second lower on-current IL2 flows in a circulating manner between the lower arm switch 117 and the lower parasitic capacitance 117b. In the lower switch component 117P, the power of the lower parasitic capacitance 117b is consumed by the internal resistance of the lower arm switch 117 and the internal resistance of the lower switch component 117P, and as a result, the power of the lower parasitic capacitance 117b is discharged to the lower arm switch 117. As described above, when the inverter circuit 85 is in the upper on-state, the residual power of the smoothing capacitor 114 is stored in the lower parasitic capacitance 117b by the first upper on-current IH1.

[0206] Returning to FIG. 16, in step S706, the flight control device 40 measures the bottom on-time TL. The bottom on-time TL is the duration for which the bottom on-processing continues. The bottom on-time TL is the elapsed time after the inverter circuit 85 transitions to the bottom on state. As the bottom on-time TL increases, the amount of charge stored in the upper parasitic capacitance 116b increases due to the first bottom on-current IL1, and the upper parasitic voltage VdsH (see FIG. 19) increases. The upper parasitic voltage VdsH is the voltage of the upper parasitic capacitance 116b. As the bottom on-processing continues, the upper parasitic voltage VdsH reaches the upper peak voltage VdsHp. The upper peak voltage VdsHp is a value determined by the amount of residual power in the smoothing capacitor 114, the size of the upper parasitic capacitance 116b, and other factors. The upper peak voltage VdsHp is the maximum value of the upper parasitic voltage VdsH during the period for which the bottom on-processing continues. During the period in which the low-side ON process continues, the high-side parasitic voltage VdsH reaches the high-side peak voltage VdsHp and is then maintained at the high-side peak voltage VdsHp.

[0207] In step S707, the flight control device 40 determines whether the lower on-time TL has reached the lower on-threshold JTL. The lower on-threshold JTL is a value determined in advance through testing or the like, and is stored in the memory 43 or the like. The lower on-threshold JTL is set to, for example, 50 μsec. The lower on-threshold JTL is a value indicating the upper limit of the lower on-time TL. The lower on-threshold JTL is set to a value indicating a time longer than the time required for the upper parasitic voltage VdsH to reach the upper peak voltage VdsHp.

[0208] If the bottom on-time TL has not reached the bottom on-threshold JTL, the flight control device 40 continues the current bottom on-processing and ends the discharge control process. In this case, the flight control device 40 repeatedly executes the processes of steps S701 and S705 to S707 until the bottom on-time TL reaches the bottom on-threshold JTL. In steps S705 to S707, the flight control device 40 maintains the inverter circuit 85 in the bottom on state so that the residual power of the smoothing capacitor 114 is stored in the upper parasitic capacitance 116b and the power of the upper parasitic capacitance 116b is discharged to the upper arm switch 116. The function of the flight control device 40 that executes the processes of steps S705 to S707 corresponds to a bottom maintaining unit.

[0209] When the bottom on time TL reaches the bottom on threshold JTL, the flight control device 40 determines that this bottom on process is complete, proceeds to step S708, and counts the up / down counter Ca. The up / down counter Ca counts the number of times the smoothing capacitor 114 has been discharged by the bottom on process, in addition to the number of times the smoothing capacitor 114 has been discharged by the bottom on process.

[0210] If the up / down counter Ca is an odd number and the down-on process has been executed, the up / down counter Ca is counted up to an even number. Also, if the down-on time TL reaches the down-on threshold JTL, the flight control device 40 resets the down-on time TL to zero. In step S709, if the up / down counter Ca has not reached the up / down counter threshold TCa, the flight control device 40 performs the process of step S701 in the next discharge control process.

[0211] The flight control device 40 continues the up-on processing for the up-on threshold JTH1 until the up-down counter Ca reaches the up-down counter threshold TCa, and then executes it again after an interval of the down-on threshold JTL. The flight control device 40 continues the down-on processing for the down-on threshold JTL until the up-down counter Ca reaches the up-down counter threshold TCa, and then executes it again after an interval of the up-on threshold JTH. The up-on threshold JTH is a value that indicates the duration of the up-on processing and also a value that indicates the cycle of the down-on processing. The down-on threshold JTL1 is a value that indicates the duration of the down-on processing and also a value that indicates the cycle of the up-on processing. The up-on threshold JTH and the down-on threshold JTL are set to the same value. Note that the up-on threshold JTH and the down-on threshold JTL may be set to different values.

[0212] The flight control device 40 alternately repeats the up-down counter Ca threshold value TCa with the up-down counter Ca threshold value TCa and the down-down counter Ca threshold value TCa. When the up-down counter Ca reaches the up-down counter Ca threshold value TCa, the flight control device 40 proceeds to step S710. The flight control device 40 performs the all-off process in step S710. The all-off process is a process for transitioning the inverter circuit 85 from the up-down counter Ca threshold value TCa to the all-off state. In the all-off state, both the upper arm switch 116 and the lower arm switch 117 are in the off state for all of the multiple phases. The all-off state is sometimes referred to as the all-shut state. Furthermore, when the up-down counter Ca reaches the up-down counter Ca threshold value TCa, the flight control device 40 resets the up-down counter Ca to zero.

[0213] In step S711, the flight control device 40 performs a discharge notification process similar to step S205 in the first embodiment. In the discharge notification process of this embodiment, the fact that the smoothing capacitor 114 has been discharged is notified by the up-ON process and the down-ON process.

[0214] The flight control device 40 repeatedly executes flight control processing to repeatedly transition the inverter circuit 85 between the up-ON state and the down-ON state in steps S701 to S709. The function in the flight control device 40 that executes the processing in steps S701 to S709 corresponds to the conversion transition unit. In steps S701 to S711, the flight control device 40 operates the arm switches 116, 117 so that the residual power in the smoothing capacitor 114 is discharged to the inverter circuit 85. The function in the flight control device 40 that executes the processing in steps S701 to S711 corresponds to the conversion discharge unit.

[0215] When repeatedly executing the upper-ON process and the lower-ON process, the flight control device 40 prevents both the upper arm switch 116 and the lower arm switch 117 from being in the ON state in one phase. In other words, the flight control device 40 repeatedly executes the upper-ON process and the lower-ON process so as to prevent a short circuit between the P line 111 and the N line 112 via the upper arm switch 116 and the lower arm switch 117. For example, when transitioning the inverter circuit 85 from one of the upper-ON state and the lower-ON state to the other, the flight control device 40 transitions the inverter circuit 85 from one state to an all-OFF state, and then transitions the inverter circuit 85 from the all-OFF state to the other.

[0216] Next, the manner in which the residual power of the smoothing capacitor 114 is reduced by the discharge control process will be described with reference to Fig. 19. In Fig. 19, the upper arm switch 116 is shown as SW_H, the lower arm switch 117 is shown as SW_L, the on state is shown as ON, and the off state is shown as OFF.

[0217] As shown in Figure 19, at timing t1, with the start of the upper-side ON process, the upper arm switch 116 is switched to the ON state, and the lower arm switch 117 is switched to the OFF state. The upper-side ON time TH increases with the start of the upper-side ON process. The upper / lower-side counter Ca starts counting from zero with the start of the discharge control process. The lower-side parasitic voltage VdsL starts increasing with the start of the upper-side ON process, and after reaching the lower-side peak voltage VdsLp, is maintained at the lower-side peak voltage VdsLp until the upper-side ON process ends.

[0218] In the smoothing capacitor 114, the capacitor voltage Vdc decreases as the lower parasitic voltage VdsL increases. The capacitor voltage Vdc is the voltage of the smoothing capacitor 114. The capacitor voltage Vdc decreases as the residual power of the smoothing capacitor 114 decreases. During the period in which the lower parasitic voltage VdsL is held at the lower peak voltage VdsLp, the capacitor voltage Vdc is also held.

[0219] At timing t2, the upper on-time TH reaches the upper on-threshold JTH, the upper on-processing is terminated, and the lower on-processing is started. When the upper on-time TH reaches the upper on-threshold JTH, the upper on-time TH is reset to zero, and the upper / lower counter Ca is incremented by 1. At timing t2, the upper arm switch 116 is switched to the OFF state, and the lower arm switch 117 is switched to the ON state. The lower on-time TL increases as the lower on-processing is started.

[0220] The upper parasitic voltage VdsH starts to increase as the lower-side ON process starts, and after reaching the upper peak voltage VdsHp, is maintained at the upper peak voltage VdsHp until the lower-side ON process ends. The lower-side parasitic voltage VdsL starts to decrease as the upper-side ON process ends, drops to almost zero, and is maintained at almost zero until the next upper-side ON process starts. In the smoothing capacitor 114, the capacitor voltage Vdc decreases as the upper parasitic voltage VdsH increases. During the period in which the upper parasitic voltage VdsH is maintained at the upper peak voltage VdsHp, the capacitor voltage Vdc is also maintained.

[0221] At timing t3, the lower on-time TL reaches the lower on-threshold JTL, the lower on-processing is terminated, and a second upper on-processing is initiated. When the lower on-time TL reaches the lower on-threshold JTL, the lower on-time TL is reset to zero, and the upper / lower counter Ca is incremented by 1. At timing t3, the lower arm switch 117 is switched to the OFF state, and the upper arm switch 116 is switched to the ON state.

[0222] In the second upper-side on-processing, similar to the previous upper-side on-processing, the lower parasitic voltage VdsL begins to increase with the start of the upper-side on-processing and reaches the lower peak voltage VdsLp. The lower peak voltage VdsLp in the second upper-side on-processing is smaller than the lower peak voltage VdsLp in the first upper-side on-processing, due to factors such as a decrease in the residual power of the smoothing capacitor 114. In the inverter device 80, the lower peak voltage VdsLp decreases stepwise each time the upper-side on-processing is repeated.

[0223] At timing t4, the upper on-time TH reaches the upper on-threshold JTH, the upper on-processing ends, and a second lower on-processing starts. When the upper on-time TH reaches the upper on-threshold JTH, the upper on-time TH is reset to zero, and the upper / lower counter Ca is incremented by 1. At timing t4, the upper arm switch 116 is switched to the off state, and the lower arm switch 117 is switched to the off state.

[0224] In the second low-side ON process, similar to the previous low-side ON process, the high-side parasitic voltage VdsH starts to increase with the start of the low-side ON process and reaches the high-side peak voltage VdsHp. The high-side peak voltage VdsHp in the second low-side ON process is smaller than the high-side peak voltage VdsHp in the first low-side ON process due to factors such as a decrease in the residual power of the smoothing capacitor 114. In the inverter device 80, the high-side peak voltage VdsHp decreases stepwise each time the low-side ON process is repeated.

[0225] In the discharge control process, the upper on threshold JTH and the lower on threshold JTL are set so that the temperature of the inverter circuit 85 does not become too high. The upper on threshold JTH is set to a value indicating a longer time period so that the temperatures of the upper switch component 116P and the lower switch component 117P do not become too high in the upper on process. For example, the upper on threshold JTH is set so that heat dissipation from the lower switch component 117P is sufficient during the period in which the lower parasitic voltage VdsL is maintained at the lower peak voltage VdsLp, even if the upper switch component 116P generates heat due to the charging of the lower parasitic capacitance 117b. Furthermore, the upper on threshold JTH is set so that heat dissipation from the upper switch component 116P is sufficient during the period in which the upper parasitic voltage VdsH is maintained at approximately zero, even if the upper switch component 116P generates heat due to the discharging of the upper parasitic capacitance 116b.

[0226] The lower on-threshold JTL is set to a value indicating a relatively long time so that the temperatures of the upper switch component 116P and the lower switch component 117P do not become too high during the lower on-process. For example, the lower on-threshold JTL is set so that heat dissipation from the upper switch component 116P is sufficient during the period in which the upper parasitic voltage VdsH is maintained at the upper peak voltage VdsHp, even if the upper switch component 116P generates heat due to the charging of the upper parasitic capacitance 116b. Furthermore, the lower on-threshold JTL is set so that heat dissipation from the lower switch component 117P is sufficient during the period in which the lower parasitic voltage VdsL is maintained at approximately zero, even if the lower switch component 117P generates heat due to the discharging of the lower parasitic capacitance 117b.

[0227] In particular, when the temperatures of the switch components 116P and 117P are high, such as immediately after the driving of the motor 61 is stopped, it is preferable to discharge the smoothing capacitor 114 while dissipating heat from the switch components 116P and 117P. In contrast, in this embodiment, the upper on-threshold JTH and the lower on-threshold JTL are set so that the temperatures of the switch components 116P and 117P are lower than immediately after the driving of the motor 61 is stopped.

[0228] According to this embodiment, the flight control device 40 operates the arm switches 116, 117 so that the residual power in the smoothing capacitor 114 is discharged to the inverter circuit 85. With this configuration, it is possible to discharge the smoothing capacitor 114 without using a dedicated discharge circuit for discharging the residual charge in the smoothing capacitor 114. This makes it possible to improve the safety of the eVTOL 10 while avoiding the propulsion device 100 from being increased in size by the amount of the dedicated discharge circuit.

[0229] In this embodiment, it is possible to consume the residual charge in the smoothing capacitor 114 by utilizing the switching loss of the inverter circuit 85. Therefore, the propulsion device 100 does not require an additional device such as a dedicated discharge circuit. Furthermore, the propulsion device 100 does not need to energize the motor 61, and does not need to move the propeller 20. Therefore, there is no concern that the airframe 11 will become unstable, and the discharge current of the smoothing capacitor 114 can be adjusted arbitrarily by adjusting the capacitances of the parasitic capacitances 116b and 117b and the upper on-threshold JTH and the lower on-threshold JTL, without the need for monitoring means such as a current sensor for monitoring the state of the propulsion device 100.

[0230] According to this embodiment, the flight control device 40 repeatedly transitions the inverter circuit 85 between the upper on state and the lower on state. With this configuration, when the inverter circuit 85 is in the upper on state, the residual power of the smoothing capacitor 114 can be stored in the lower parasitic capacitance 117b, while the power stored in the upper parasitic capacitance 116b can be discharged to the upper arm switch 116. Furthermore, when the inverter circuit 85 is in the lower on state, the residual power of the smoothing capacitor 114 can be stored in the upper parasitic capacitance 116b, while the power stored in the lower parasitic capacitance 117b can be discharged to the lower arm switch 117. Therefore, by repeatedly transitioning the inverter circuit 85 between the upper on state and the lower on state, the smoothing capacitor 114 can be discharged using the arm switches 116 and 117, the parasitic capacitances 116b and 117b, etc.

[0231] According to this embodiment, the flight control device 40 maintains the inverter circuit 85 in the upper on state so that the residual power of the smoothing capacitor 114 is stored in the lower parasitic capacitance 117b and so that the power of the upper parasitic capacitance 116b is discharged to the upper arm switch 116. The flight control device 40 also maintains the inverter circuit 85 in the lower on state so that the residual power of the smoothing capacitor 114 is stored in the upper parasitic capacitance 116b and so that the power of the lower parasitic capacitance 117b is discharged to the lower arm switch 117. Therefore, the residual power of the smoothing capacitor 114 can be discharged to the arm switches 116 and 117 via the parasitic capacitances 116b and 117b.

[0232] The propulsion device 100 mounted on the eVTOL 10 may be designed to increase motor output and reduce the inductance of the motor 61. For this reason, the propulsion device 100 requires a high switching frequency for the inverter circuit 85. In contrast, in this embodiment, the parasitic capacitances 116b, 117b of the arm switches 116, 117 tend to increase, and the inverter circuit 85 can be driven at a high switching frequency. For this reason, it is possible to discharge the smoothing capacitor 114 in a short time simply by charging and discharging the parasitic capacitance 116b.

[0233] Eighth Embodiment In the eighth embodiment, in the discharge control process, the switching of the inverter circuit 85 in the first inverter device 801 and the switching of the inverter circuit 85 in the second inverter device 802 are performed at different timings. The configurations, actions, and effects not specifically described in the eighth embodiment are the same as those in the seventh embodiment. The eighth embodiment will be described mainly focusing on the differences from the seventh embodiment.

[0234] 20, similarly to the first embodiment, the first inverter device 801 and the second inverter device 802 are electrically connected to a common battery 31. The propulsion system 30 has a battery voltage sensor 151. The battery voltage sensor 151 is a sensor that detects the voltage of the battery 31. The battery voltage sensor 151a has the same configuration as the battery voltage sensors 151a and 151b.

[0235] In this embodiment, the inverter circuit 85 and smoothing capacitor 114 included in the first inverter device 801 are referred to as a first inverter circuit 851 and a first smoothing capacitor 114a. The first inverter circuit 851 corresponds to a power conversion unit and a first conversion unit. The inverter circuit 85 and smoothing capacitor 114 included in the second inverter device 802 are referred to as a second inverter circuit 852 and a second smoothing capacitor 114b. The second inverter circuit 852 corresponds to a power conversion unit and a second conversion unit.

[0236] The first inverter circuit 851 and the first smoothing capacitor 114a, and the second inverter circuit 852 and the second smoothing capacitor 114b are connected in parallel to the battery 31 and the power supply switch 132. Therefore, the first inverter circuit 851 and the first smoothing capacitor 114a, and the second inverter circuit 852 and the second smoothing capacitor 114b are connected to each other via the P line 111 and the N line 112 so as to be electrically conductive to each other.

[0237] The flight control device 40 causes the first inverter circuit 851 to discharge the first smoothing capacitor 114a and the second inverter circuit 852 to discharge the second smoothing capacitor 114b in parallel. Meanwhile, the flight control device 40 causes the first inverter circuit 851 to switch to discharge the first smoothing capacitor 114a and the second inverter circuit 852 to switch to discharge the second smoothing capacitor 114b at different times.

[0238] In this embodiment, the discharge control process will be described with reference to the flowchart in Fig. 21. This discharge control process includes both a process performed on the first inverter device 801 and a process performed on the second inverter device 802. For example, the discharge control process includes a process of discharging the first smoothing capacitor 114a by switching the first inverter circuit 851, and a process of discharging the second smoothing capacitor 114b by switching the second inverter circuit 852.

[0239] 21, the flight control device 40 determines whether the common counter Cb is equal to n times 2. The flight control device 40 determines whether the common counter Cb is an even number. If the common counter Cb is an even number, the flight control device 40 proceeds to step S802.

[0240] In step S802, the flight control device 40 performs a first discharge process. The first discharge process is a process for discharging the first inverter device 801. In the first discharge process, an upper-ON process and a lower-ON process are alternately and repeatedly performed on the first inverter device 801. That is, in the first discharge process, a process is performed for repeatedly transitioning the first inverter circuit 851 between an upper-ON state and a lower-ON state. The function of the flight control device 40 that executes the process of step S802 corresponds to a first transition unit.

[0241] After the first discharge process, the flight control device 40 proceeds to step S804. In step S804, the flight control device 40 determines whether the first up / down counter Ca1 has been counted in this discharge control process. The first up / down counter Ca1 indicates the total number of times the up-ON process has been completed and the number of times the down-ON process has been completed in the first discharge process. If the first up / down counter Ca1 has been counted, the flight control device 40 determines that one of the up-ON process or the down-ON process has been completed in the first discharge process, and proceeds to step S806.

[0242] If the first up / down counter Ca1 has not been counted, the flight control device 40 proceeds to step S805. In step S805, the flight control device 40 determines whether the second up / down counter Ca2 has been counted in the current discharge control process. The second up / down counter Ca2 indicates the total number of times the up-ON process has been completed and the number of times the down-ON process has been completed in the second discharge process. If the second up / down counter Ca2 has been counted, the flight control device 40 determines that one of the up-ON process and the down-ON process has been completed in the second discharge process, and proceeds to step S806.

[0243] When the first up-down counter Ca1 or the second up-down counter Ca2 has been counted, the flight control device 40 counts the common counter Cb in step S806. The flight control device 40 increments the common counter Cb by a predetermined increment. For example, the flight control device 40 sets the increment to 1 and increments the common counter Cb by 1. The common counter Cb is set in the memory 43 or the like. If the common counter Cb is an even number after the first discharge process has been executed, the common counter Cb becomes an odd number when counted.

[0244] In step S807, the flight control device 40 determines whether the common counter Cb has reached a common counter threshold TCb. The common counter threshold TCb is a value determined in advance through testing or the like, and is stored in the memory 43 or the like. The common counter threshold TCb indicates the number of times the first discharge process and the second discharge process described below are executed. The larger the common counter threshold TCb, the greater the number of times the first discharge process and the second discharge process are executed. The common counter threshold TCb sets the length of time during which the first inverter device 801 continues to discharge through the first discharge process, and the length of time during which the second inverter device 802 continues to discharge through the second discharge process.

[0245] If the common counter Cb has not reached the common counter threshold value TCb, the flight control device 40 ends the discharge control process. In this case, the flight control device 40 executes the process of step S801 in the next discharge control process.

[0246] If the common counter Cb is not an even number in step S801, the flight control device 40 proceeds to step S803. In step S803, the flight control device 40 performs a second discharge process. The second discharge process is a process for discharging the second inverter device 802. In the second discharge process, an upper-ON process and a lower-ON process are alternately and repeatedly performed on the second inverter device 802. In other words, in the second discharge process, a process is performed for repeatedly transitioning the second inverter circuit 852 between an upper-ON state and a lower-ON state. The second discharge process will be described later. The function of the flight control device 40 that executes the process of step S803 corresponds to a second transition unit.

[0247] After the second discharge process, the flight control device 40 performs the processes of steps S804 and S805. If the first up-down counter Ca1 or the second up-down counter Ca2 is counted in steps S804 and S805, the flight control device 40 proceeds to step S806 and counts the common counter Cb. If the common counter Cb is an odd number after the second discharge process has been performed, the common counter Cb becomes an even number after being counted. If the common counter Cb has not reached the common counter threshold value TCb in step S807, the flight control device 40 performs the process of step S801 in the next discharge control process.

[0248] The flight control device 40 alternately repeats the first discharge process of step S802 and the second discharge process of step S803 until the common counter Cb reaches the common counter threshold TCb. When the common counter Cb reaches the common counter threshold TCb, the flight control device 40 proceeds to step S808 and performs all-off processing. The all-off processing is processing for transitioning each of the first inverter circuit 851 and the second inverter circuit 852 to an all-off state. Furthermore, when the common counter Cb reaches the common counter threshold TCb, the flight control device 40 resets the common counter Cb to zero.

[0249] In step S809, the flight control device 40 performs a discharge notification process similar to step S205 in the first embodiment. In the discharge notification process of this embodiment, it is notified that the first inverter device 801 and the second inverter device 802 have been discharged by the first discharge process and the second discharge process.

[0250] The flight control device 40 repeatedly executes flight control processing to repeatedly transition the inverter circuits 851, 852 between the up-ON state and the down-ON state in steps S801 to S807. The function in the flight control device 40 that executes the processing in steps S801 to S807 corresponds to a conversion transition unit. In steps S801 to S809, the flight control device 40 operates the arm switches 116, 117 so that the residual power in the smoothing capacitors 114a, 114b is discharged to the inverter circuits 851, 852. The function in the flight control device 40 that executes the processing in steps S801 to S809 corresponds to a conversion discharge unit.

[0251] The flight control device 40 shifts the timing at which the first inverter circuit 851 transitions from one of the up-ON state and the down-ON state to the other so that it does not coincide with the timing at which the second inverter circuit 852 transitions from one of the up-ON state and the down-ON state to the other. For example, the flight control device 40 uses a common counter Cb to shift the timing at which the up-ON process or the down-ON process starts in the first discharge process and the timing at which the up-ON process or the down-ON process starts in the second discharge process. The function of the flight control device 40 that executes the processing of steps S801, S806, and S807 corresponds to a timing shifting unit.

[0252] Next, the first discharge process will be described with reference to the flowchart in Figure 22. The flight control device 40 performs the processes of steps S901 to S908 shown in Figure 22. The processes of steps S901 to S908 correspond to the processes of steps S701 to S708 in the seventh embodiment. In the first discharge process, the up / down counter Ca will be referred to as the first up / down counter Ca1, the up on time TH will be referred to as the first up on time TH1, and the up on threshold JTH will be referred to as the first up on threshold JTH1. In addition, the down on time TL will be referred to as the first down on time TL1, and the down on threshold JTL will be referred to as the first down on threshold JTL1.

[0253] If the first up / down counter Ca1 is an even number in step S901, the flight control device 40 performs up-on processing in step S902 and measures the first up-on time TH1 in step S903. The flight control device 40 continues the up-on processing until the first up-on time TH1 reaches the first up-on threshold JTH1 in step S904. If the first up-on time TH1 reaches the first up-on threshold JTH1, the flight control device 40 counts the first up / down counter Ca1 in step S908.

[0254] If the first up / down counter Ca1 is not an even number, the flight control device 40 performs down-on processing in step S905 and measures the first down-on time TL1 in step S906. The flight control device 40 continues the down-on processing until the first down-on time TL1 reaches the first down-on threshold JTL1 in step S907. If the first down-on time TL1 reaches the first down-on threshold JTL1, the flight control device 40 counts the first up / down counter Ca1 in step S908.

[0255] The second discharge process will be described with reference to the flowchart in Figure 23. The flight control device 40 performs the processes of steps S1001 to S1008 shown in Figure 23. The processes of steps S1001 to S1008 correspond to the processes of steps S701 to S708 in the seventh embodiment. In the second discharge process, the up / down counter Ca will be referred to as the second up / down counter Ca2, the up on time TH will be referred to as the second up on time TH2, and the up on threshold JTH will be referred to as the second up on threshold JTH2. In addition, the down on time TL will be referred to as the second down on time TL2, and the down on threshold JTL will be referred to as the second down on threshold JTL2.

[0256] If the second up / down counter Ca2 is an even number in step S1001, the flight control device 40 performs up-on processing in step S1002 and measures the second up-on time TH2 in step S1003. The flight control device 40 continues the up-on processing until the second up-on time TH2 reaches the second up-on threshold JTH2 in step S1004. If the second up-on time TH2 reaches the second up-on threshold JTH2, the flight control device 40 counts the second up / down counter Ca2 in step S1008.

[0257] If the second up / down counter Ca2 is not an even number, the flight control device 40 performs down-on processing in step S1005 and measures the second down-on time TL2 in step S1006. The flight control device 40 continues the down-on processing until the second down-on time TL2 reaches the second down-on threshold JTL2 in step S1007. When the second down-on time TL2 reaches the second down-on threshold JTL2, the flight control device 40 counts the second up / down counter Ca2 in step S1008.

[0258] Next, the switching behavior of the inverter circuits 851, 852 due to the discharge control process will be described with reference to Fig. 24. In Fig. 24, the first inverter circuit 851 is illustrated as INV1, and the second inverter circuit 852 is illustrated as INV2. In the first inverter circuit 851 and the second inverter circuit 852, the parasitic voltages VdsH, VdsL change in response to the start and end of the upper-side ON process and the lower-side ON process, similar to the parasitic voltages VdsH, VdsL in the seventh embodiment.

[0259] 24, at timing t11, the upper-side ON process is started in the first discharge process, and the upper arm switch 116 is switched to the ON state and the lower arm switch 117 is switched to the OFF state in the first inverter circuit 851. Then, at timing t12, the upper-side ON process is ended in the first discharge process and the lower-side ON process is started. In the first inverter circuit 851, the second upper-side ON process is started at timing t13, and the second lower-side ON process is started at timing t14.

[0260] In the second discharge process, the top-on process is started at a timing different from the top-on process and bottom-on process of the first discharge process. For example, the top-on process of the second discharge process is started at timing t11a. This timing t11a is between timing t11, when the top-on process of the first discharge process is started, and timing t12, when the bottom-on process of the first discharge process is started. In the discharge control process, the first discharge process and the second discharge process are alternately performed depending on whether the common counter Cb is an even number, so timing t11a is midway between timing t11 and timing t12.

[0261] Furthermore, in the second discharge process, the bottom-on process is started at a different timing than the top-on process and the bottom-on process of the first discharge process. For example, the bottom-on process of the second discharge process is started at timing t12a. This timing t12a is between timing t12 when the bottom-on process of the first discharge process starts and timing t13 when the top-on process of the first discharge process starts. In the discharge control process, the first discharge process and the second discharge process are alternately performed depending on whether the common counter Cb is an even number, so timing t12a is midway between timing t12 and timing t13.

[0262] According to this embodiment, the flight control device 40 staggers the timing at which the first inverter circuit 851 transitions from one of the up-on state and the down-on state to the other and the timing at which the second inverter circuit 852 transitions from one of the up-on state and the down-on state to the other. With this configuration, even if noise such as EMC noise occurs due to switching of the inverter circuits 851 and 852, the timing at which the noise occurs can be staggered between the first inverter circuit 851 and the second inverter circuit 852. This makes it possible to prevent abnormalities from occurring in the inverter circuits 851 and 852 due to, for example, overlapping of noise generated in the first inverter circuit 851 and the second inverter circuit 852.

[0263] In this embodiment, the first inverter circuit 851 and the second inverter circuit 852 are electrically connected via the P line 111 and the N line 112. In this configuration, there is a concern that noise generated due to switching of the inverter circuits 851 and 852 may be transmitted to the inverter circuits 851 and 852 or the filter circuit via the P line 111 and the N line 112. For example, the filter circuit is a DC-side filter circuit and is provided between the battery 31 and the smoothing capacitors 114a and 114b. In contrast, according to this embodiment, the timing of noise generation due to switching differs between the first inverter circuit 851 and the second inverter circuit 852, so that the peak value of noise transmitted to the filter circuit, etc., can be reduced.

[0264] Ninth Embodiment In the seventh embodiment, when the top-on process and the bottom-on process are alternately repeated, the duration of the top-on process and the bottom-on process is kept constant. In contrast, in the ninth embodiment, the duration of the top-on process and the bottom-on process is gradually shortened. The configurations, actions, and effects of the ninth embodiment that are not specifically described are the same as those of the seventh embodiment. The ninth embodiment will be described mainly focusing on the differences from the seventh embodiment.

[0265] In this embodiment, the discharge control process will be described with reference to the flowchart in Figure 25. The flight control device 40 executes the processes of steps S701 to S711, as in the seventh embodiment. After executing the upper on process in step S702, if the upper on time TH reaches the upper on threshold JTH in step S704, the flight control device 40 proceeds to step S1101.

[0266] In step S1101, the flight control device 40 subtracts the upper subtraction value VaH from the upper on threshold JTH. The upper subtraction value VaH is a value determined in advance through testing or the like, and is stored in memory 43 or the like. The upper subtraction value VaH is set to, for example, several microseconds. The upper on threshold JTH1 decreases by the upper subtraction value VaH each time the upper on processing is repeated. The flight control device 40 shortens the period for which the next upper on processing will continue compared to the period for which the current upper on processing will continue. The function of the flight control device 40 that executes the processing of step S1101 corresponds to the upper shortening unit.

[0267] For example, as shown in FIG. 26, the next upper on threshold JTH_n+1 is smaller than the current upper on threshold JTH_n by the upper subtraction value VaH. The next upper on threshold JTH_n+1 corresponds to the period during which the next upper on state is maintained. The current upper on threshold JTH_n corresponds to the period during which the current upper on state is maintained. Each time the inverter circuit 85 transitions to the upper on state, the period during which the inverter circuit 85 is maintained in the upper on state is shortened by the upper subtraction value VaH. For example, the period between timings t23 and t24 during which the second upper on process continues is shorter than the period between timings t21 and t22 during which the first upper on process continues. Furthermore, each time the inverter circuit 85 transitions to the lower on state, the interval between the two lower on states before and after the transition is shortened by the upper subtraction value VaH.

[0268] Returning to FIG. 25, after the bottom ON processing is executed in step S705, if the bottom ON time TL1 reaches the bottom ON threshold JTL in step S707, the flight control device 40 proceeds to step S1102.

[0269] In step S1102, the flight control device 40 subtracts the lower ON threshold JTL by the lower subtraction value VaL. The lower subtraction value VaL is a value determined in advance through testing or the like, and is stored in memory 43 or the like. The lower subtraction value VaL is set to, for example, several microseconds. The lower ON threshold JTL1 decreases by the lower subtraction value VaL each time the lower ON process is repeated. The flight control device 40 shortens the period for which the next lower ON process will continue than the period for which the current lower ON process will continue. The function of the flight control device 40 that executes the process of step S1102 corresponds to the lower shortening unit.

[0270] For example, as shown in FIG. 26, the next lower on threshold JTL_n+1 is smaller than the current lower on threshold JTL_n by the lower subtraction value VaL. The next lower on threshold JTL_n+1 corresponds to the period during which the next lower on state is maintained. The current lower on threshold JTL_n corresponds to the period during which the current lower on state is maintained. Each time the inverter circuit 85 transitions to the lower on state, the period during which the inverter circuit 85 is maintained in the lower on state is shortened by the lower subtraction value VaL. For example, the period between timings t24 and t25 during which the second lower on process continues is shorter than the period between timings t22 and t23 during which the first lower on process continues. Furthermore, each time the inverter circuit 85 transitions to the upper on state, the interval between the two upper on states before and after the transition is shortened by the lower subtraction value VaL.

[0271] In this embodiment, the functions of the flight control device 40 to execute the processing of steps S1101 and S1102 are included in the conversion transition unit and the conversion discharge unit.

[0272] According to this embodiment, the flight control device 40 sets the period during which the next upper on state is maintained shorter than the period during which the current upper on state is maintained, and sets the period during which the next lower on state is maintained shorter than the period during which the current lower on state is maintained, for the inverter circuit 85. This configuration can shorten the period during which the upper parasitic voltage VdsH is maintained at the upper peak voltage VdsHp and the period during which the lower parasitic voltage VdsL is maintained at the lower peak voltage VdsLp. This shortens the time required to discharge the residual power in the smoothing capacitor 114 to the inverter circuit 85.

[0273] The switch components 116P, 117P are more likely to generate heat as the peak voltages VdsHp, VdsLp increase. Furthermore, the peak voltages VdsHp, VdsLp gradually decrease as the upper-side ON process and the lower-side ON process are repeated. Therefore, the amount of heat generated by the switch components 116P, 117P decreases as the upper-side ON process and the lower-side ON process are repeated. Therefore, even if the duration of the next upper-side ON process is set shorter than the duration of the current lower-side ON process, as in this embodiment, the heat generated by the switch components 116P, 117P is unlikely to cause an increase in the temperatures of the switch components 116P, 117P. This prevents the temperatures of the switch components 116P, 117P from rising excessively, while shortening the time required for discharging the smoothing capacitor 114.

[0274] When the smoothing capacitor 114 discharges, a large amount of charge remains in the smoothing capacitor 114 immediately after the start of discharge, which tends to increase the amount of heat generated by the switch components 116P and 117P due to the operation of the inverter circuit 85. Therefore, the duration of the upper-on process and the lower-on process is initially extended to prevent overheating of the switch components 116P and 117P. As the discharge of the smoothing capacitor 114 progresses and the remaining charge in the smoothing capacitor 114 decreases, the amount of heat dissipated by the switch components 116P and 117P also tends to decrease. For this reason, shortening the duration of the upper-on process and the lower-on process quickly completes the discharge of the smoothing capacitor 114. The cycle may be changed in steps or continuously. The duration of the upper-on process and the lower-on process is sometimes simply referred to as the cycle.

[0275] Tenth Embodiment In the ninth embodiment, when the upper-side ON process and the lower-side ON process are alternately and repeatedly performed, the duration of the upper-side ON process and the lower-side ON process is gradually shortened. In contrast, in the tenth embodiment, the duration of the upper-side ON process and the lower-side ON process is set according to the state of the smoothing capacitor 114. The configurations, actions, and effects not specifically described in the tenth embodiment are the same as those of the seventh embodiment. In the tenth embodiment, the differences from the seventh embodiment will be mainly described.

[0276] In this embodiment, the discharge control process will be described with reference to the flowchart in Figure 27. The flight control device 40 executes the processes of steps S701 to S711, as in the seventh and ninth embodiments. After executing the upper ON process in step S702, if the upper ON time TH1 reaches the upper ON threshold JTH in step S704, the flight control device 40 proceeds to step S1201.

[0277] In step S1201, the flight control device 40 determines whether the inverter temperature Tinv has reached the inverter temperature threshold JTinv. The inverter temperature Tinv is the temperature of the inverter device 80. Examples of the inverter temperature Tinv include the temperatures of the switch components 116P and 117P and the temperature of the inverter circuit 85. The inverter temperature Tinv is a parameter that indicates the state of the inverter circuit 85. The flight control device 40 acquires the inverter temperature Tinv using the detection signal of the inverter temperature sensor 153. The inverter temperature threshold JTinv is a value that is determined in advance through testing or the like, and is stored in the memory 43 or the like.

[0278] If the inverter temperature Tinv reaches the inverter temperature threshold JTinv, the flight control device 40 proceeds to step S1203. In step S1203, the flight control device 40 adds the upper on threshold JTH by the upper addition value VbH. The upper addition value VbH is a value determined in advance through testing or the like and is stored in the memory 43 or the like. The upper addition value VbH is set to, for example, several microseconds. If the inverter temperature Tinv has reached the inverter temperature threshold JTinv, the upper on threshold JTH increases by the upper addition value VbH each time the upper on processing is repeated. In this case, the flight control device 40 sets the duration for the next upper on processing to be longer than the duration for the current upper on processing.

[0279] If the inverter temperature Tinv has not reached the inverter temperature threshold JTinv, the flight control device 40 proceeds to step S1202. In step S1202, the flight control device 40 determines whether the lower peak voltage VdsLp is equal to or greater than the lower peak threshold JVdsLp. The lower peak voltage VdsLp is a parameter that indicates the charge or discharge state of the lower parasitic capacitance 117b. The lower peak voltage VdsLp is one of the parameters that indicate the state of the inverter circuit 85.

[0280] The lower peak threshold JVdsLp is a value determined in advance through testing or the like, and is stored in the memory 43 or the like. The lower peak threshold JVdsLp is set to a value that prevents excessive heat from being generated in the lower switch component 117P as the lower parasitic capacitance 117b is charged or discharged. For example, when the lower peak voltage VdsLp is equal to or greater than the lower peak threshold JVdsLp, the lower switch component 117P is likely to generate a large amount of heat as the lower parasitic capacitance 117b is charged or discharged. When the lower peak voltage VdsLp is smaller than the lower peak threshold JVdsLp, the lower switch component 117P is unlikely to generate a large amount of heat even when the lower parasitic capacitance 117b is charged or discharged.

[0281] If the lower peak voltage VdsLp is equal to or greater than the lower peak threshold JVdsLp, the flight control device 40 proceeds to step S1204. In step S1204, the flight control device 40 maintains the upper on threshold JTH at its current value without increasing or decreasing it.

[0282] If the lower peak voltage VdsLp is not equal to or greater than the lower peak threshold JVdsLp, the flight control device 40 proceeds to step S1205. In step S1205, the flight control device 40 subtracts the upper subtraction value VaH from the upper on threshold JTH, similar to step S1101 in the ninth embodiment. The function of the flight control device 40 that executes the processing of step S1205 corresponds to the upper reduction unit.

[0283] In steps S1201 to S1205, the flight control device 40 variably sets the upper on threshold JTH according to the state of the inverter circuit 85. The upper on threshold JTH indicates the period during which the inverter circuit 85 is maintained in the upper on state. The upper on threshold JTH corresponds to the upper maintenance period. The function of the flight control device 40 that executes the processing of steps S1201 to S1205 corresponds to the maintenance setting unit.

[0284] As shown in FIG. 28, assume that the first and second upper-side ON processes are initiated when the inverter temperature Tinv is higher than the inverter temperature threshold JTinv. In this case, the period between times t33 and t34 during which the second upper-side ON process continues is longer than the period between times t31 and t32 during which the first upper-side ON process continues. At time t35 when the third upper-side ON process starts, the inverter temperature Tinv is lower than the inverter temperature threshold JTinv. Furthermore, during the second upper-side ON process, the lower peak voltage VdsLp is lower than the lower peak threshold JVdsLp. Therefore, the period between times t35 and t36 during which the third upper-side ON process continues is shorter than the period between times t33 and t34 during which the second upper-side ON process continues.

[0285] Returning to FIG. 27, after the bottom ON process is executed in step S705, if the bottom ON time TL reaches the bottom ON threshold JTL in step S707, the flight control device 40 proceeds to step S1206.

[0286] In step S1206, the flight control device 40 determines whether or not the inverter temperature Tinv has reached the inverter temperature threshold JTinv, similar to step S1201. If the inverter temperature Tinv has reached the inverter temperature threshold JTinv, the flight control device 40 proceeds to step S1207.

[0287] In step S1208, the flight control device 40 adds the lower on threshold JTL by the lower addition value VbL. The lower addition value VbL is a value determined in advance through testing or the like and is stored in the memory 43 or the like. The lower addition value VbL is set to, for example, several microseconds. If the inverter temperature Tinv has reached the inverter temperature threshold JTinv, the lower on threshold JTL increases by the lower addition value VbL each time the lower on processing is repeated. In this case, the flight control device 40 sets the duration for the next lower on processing to be longer than the duration for the current lower on processing.

[0288] If the inverter temperature Tinv has not reached the inverter temperature threshold JTinv, the flight control device 40 proceeds to step S1207. In step S1207, the flight control device 40 determines whether the upper peak voltage VdsHp is equal to or greater than the upper peak threshold JVdsHp. The upper peak voltage VdsHp is a parameter that indicates the charge or discharge state of the upper parasitic capacitance 116b. The upper peak voltage VdsHp is one of the parameters that indicate the state of the inverter circuit 85.

[0289] The upper peak threshold JVdsHp is a value determined in advance through testing or the like, and is stored in the memory 43 or the like. The upper peak threshold JVdsHp is set to a value that prevents excessive heat from being generated in the upper switch component 116P as the upper parasitic capacitance 116b is charged or discharged. For example, when the upper peak voltage VdsHp is equal to or greater than the upper peak threshold JVdsHp, the upper switch component 116P is likely to generate a large amount of heat as the upper parasitic capacitance 116b is charged or discharged. When the upper peak voltage VdsHp is smaller than the upper peak threshold JVdsHp, the upper switch component 116P is unlikely to generate a large amount of heat even when the upper parasitic capacitance 116b is charged or discharged.

[0290] If the upper peak voltage VdsHp is equal to or greater than the upper peak threshold JVdsHp, the flight control device 40 proceeds to step S1209. In step S1209, the flight control device 40 maintains the lower on threshold JTL at its current value without increasing or decreasing it.

[0291] If the upper peak voltage VdsHp is not equal to or greater than the upper peak threshold JVdsHp, the flight control device 40 proceeds to step S1210. In step S1210, the flight control device 40 subtracts the lower subtraction value VaL from the lower on threshold JTL, similar to step S1102 in the ninth embodiment. The function of the flight control device 40 that executes the processing of step S1210 corresponds to the lower reduction unit.

[0292] In steps S1206 to S1210, the flight control device 40 variably sets the lower on threshold JTL according to the state of the inverter circuit 85. The lower on threshold JTL indicates the period during which the inverter circuit 85 is maintained in the lower on state. The lower on threshold JTL corresponds to the lower maintenance period. The function of the flight control device 40 that executes the processing of steps S1206 to S1210 corresponds to the maintenance setting unit. Furthermore, the function of the flight control device 40 that executes the processing of steps S1201 to S1210 is included in the conversion transition unit and the conversion discharge unit.

[0293] As shown in FIG. 28, assume that the first and second low-side ON processes are initiated when the inverter temperature Tinv is higher than the inverter temperature threshold JTinv. In this case, the period between times t34 and t35 during which the second low-side ON process continues is longer than the period between times t32 and t33 during which the first low-side ON process continues. At time t36 when the third low-side ON process starts, the inverter temperature Tinv is lower than the inverter temperature threshold JTinv. Furthermore, during the second low-side ON process, the upper peak voltage VdsHp is lower than the upper peak threshold JVdsHp. Therefore, the period between times t36 and t37 during which the third low-side ON process continues is shorter than the period between times t32 and t33 during which the second low-side ON process continues.

[0294] According to this embodiment, the flight control device 40 sets the time for which the inverter circuit 85 is maintained in the upper on state and the time for which the inverter circuit 85 is maintained in the lower on state, depending on the state of the inverter circuit 85. With this configuration, it is possible to prioritize either suppressing a temperature rise in the inverter circuit 85 or shortening the discharge time of the smoothing capacitor 114, depending on the state of the inverter circuit 85. For example, when the inverter temperature Tinv is relatively high, it is possible to prioritize suppressing a temperature rise in the inverter circuit 85 over shortening the discharge time of the smoothing capacitor 114, and to lengthen the time for which the inverter circuit 85 is maintained in the upper on state or the lower on state. In this case, the period for which the parasitic voltages VdsH and VdsL are maintained at the peak voltages VdsHp and VdsLp is extended, which facilitates heat dissipation from the inverter circuit 85.

[0295] Furthermore, when the inverter temperature Tinv is relatively low, it is possible to shorten the time for which the inverter circuit 85 is maintained in the high-side ON state or the low-side ON state, giving priority to shortening the discharge time of the smoothing capacitor 114 over suppressing the temperature rise of the inverter circuit 85. In this case, the time for which the parasitic voltages VdsH, VdsL are maintained at the peak voltages VdsHp, VdsLp is shortened, which tends to shorten the time required for discharging the smoothing capacitor 114.

[0296] In this embodiment, to quickly discharge the smoothing capacitor 114, it is desirable to switch the arm switches 116 and 117 at high speed. In other words, it is desirable to shorten the cycle in which the inverter circuit 85 transitions between the upper-side on state and the lower-side on state. However, there is a concern that the inverter circuit 85 may overheat if it is driven without cooling air to actively cool the inverter circuit 85. In response to this, appropriate discharge control can be achieved by optimizing the cycle in which the inverter circuit 85 transitions between the upper-side on state and the lower-side on state, taking into account circumstances different from those when driving a motor.

[0297] Eleventh Embodiment In the eleventh embodiment, capacitors other than the parasitic capacitances 116b and 117b are provided for the arm switches 116 and 117. The configurations, actions, and effects not specifically described in the eleventh embodiment are the same as those of the seventh embodiment. The eleventh embodiment will be described mainly focusing on the differences from the seventh embodiment.

[0298] As shown in Fig. 29, the inverter device 80 has an upper snubber capacitor 161 and a lower snubber capacitor 162. The upper snubber capacitor 161 is connected in parallel to the upper arm switch 116. The upper snubber capacitor 161 can reduce noise such as surge voltages generated by switching of the upper arm switch 116. The upper snubber capacitor 161 is connected in parallel to the upper parasitic capacitance 116b. The upper snubber capacitor 161 may or may not be included in the upper switch component 116P.

[0299] The lower snubber capacitor 162 is provided in parallel with the lower arm switch 117. The lower snubber capacitor 162 can reduce noise such as surge voltage generated by switching of the lower arm switch 117. The lower snubber capacitor 162 is connected in parallel with the lower parasitic capacitance 117b. The lower snubber capacitor 162 may or may not be included in the lower switch component 117P.

[0300] When the inverter circuit 85 is shifted to the upper on state, the residual power of the smoothing capacitor 114 is stored in the lower snubber capacitor 162 in addition to the lower parasitic capacitance 117b. Then, the power stored in the upper parasitic capacitance 116b and the power stored in the upper snubber capacitor 161 is discharged to the upper arm switch 116. When the inverter circuit 85 is shifted to the lower on state, the residual power of the smoothing capacitor 114 is stored in the upper snubber capacitor 161 in addition to the upper parasitic capacitance 116b. Then, the power stored in the lower snubber capacitor 162 in addition to the power stored in the lower parasitic capacitance 117b is discharged to the lower arm switch 116. Therefore, the snubber capacitors 161 and 162 can shorten the time required for discharging the smoothing capacitor 114.

[0301] Note that snubber resistors may be connected in series to the snubber capacitors 161 and 162. In this configuration, the power stored in the snubber capacitors 161 and 162 is likely to be consumed by the snubber resistors.

[0302] <Twelfth embodiment> In the twelfth embodiment, discharge control is started after cutoff of the power supply to the motor 61 is detected. The configurations, actions, and effects of the twelfth embodiment that are not specifically described are the same as those of the sixth embodiment. The twelfth embodiment will be described mainly focusing on the differences from the sixth embodiment.

[0303] 30, like the eighth embodiment, the propulsion system 30 has a battery voltage sensor 151 and a capacitor voltage sensor 152. The capacitor voltage sensor 152 is provided in each of the first inverter device 801 and the second inverter device 802.

[0304] In this embodiment, the flight control process will be described with reference to the flowchart in Figure 31. The flight control device 40 executes the processes of steps S601 to S614, similar to the sixth embodiment. After the forced shutdown process of step S606 is performed, the flight control device 40 proceeds to step S1301.

[0305] In step S1301, the flight control device 40 determines whether the capacitor voltage Vdc is smaller than the capacitor voltage threshold TVdc. The flight control device 40 acquires the capacitor voltage Vdc using the detection signal of the capacitor voltage sensor 152. The capacitor voltage threshold TVdc is a value determined in advance through testing or the like, and is stored in the memory 43 or the like. The capacitor voltage threshold TVdc is set to a value that indicates that the power supply from the battery 31 to the inverter circuit 85 has been cut off.

[0306] If the capacitor voltage Vdc is lower than the capacitor voltage threshold TVdc, the flight control device 40 determines that the power supply from the battery 31 to the inverter circuit 85 has been cut off, and performs the forced discharge process in step S607. This prevents a situation in which the forced discharge process is performed in step S607 even though the power supply from the battery 31 to the inverter circuit 85 was not properly cut off in step S606.

[0307] When the power supply switch 132 is normally disconnected, the capacitor voltage Vdc, which is the voltage of the high-voltage DC path in the inverter device 80, should drop to a value corresponding to the voltage of the battery 31. Therefore, the capacitor voltage threshold TVdc is set to a value lower than the voltage range in the energized state and higher than the voltage range in the disconnected state. The voltage range in the energized state is the voltage range that can be detected by the capacitor voltage sensor 152 when the power supply switch 132 is in the energized state. The voltage range in the disconnected state is the voltage range that can be generated by the residual power in the smoothing capacitor 114 when the power supply switch 132 is in the disconnected state. This allows the propulsion system 30 to start discharge control appropriately and reliably without malfunctioning.

[0308] After performing the interlock cutoff processing in step S611, the flight control device 40 proceeds to step S1302. In step S1302, the flight control device 40 determines whether the capacitor voltage Vdc is lower than the capacitor voltage threshold TVdc, as in step S1301. If the capacitor voltage Vdc is lower than the capacitor voltage threshold TVdc, the flight control device 40 performs the inverter lock discharge processing in step S612. This prevents a situation in which the interlock discharge processing is performed in step S612 even though the power supply from the battery 31 to the inverter circuit 85 was not properly cut off in step S611.

[0309] After the power-off process of step S613 is performed, the flight control device 40 proceeds to step S1303. In step S1303, the flight control device 40 determines whether the capacitor voltage Vdc is lower than the capacitor voltage threshold TVdc, as in step S1301. If the capacitor voltage Vdc is lower than the capacitor voltage threshold TVdc, the flight control device 40 performs the off-discharge process of step S614. This prevents a situation in which the off-discharge process is performed in step S614 even though the power supply from the battery 31 to the inverter circuit 85 was not properly cut off in step S613.

[0310] To prevent malfunctions, it is preferable that the discharge control start conditions in all of steps S607, S612, and S614 include the capacitor voltage Vdc being smaller than the capacitor voltage threshold TVdc. However, in processes that prioritize starting discharge as quickly as possible, such as forced discharge processes and interlock discharge processes that require discharge in a short period of time, the discharge control start conditions do not necessarily include the capacitor voltage Vdc being smaller than the capacitor voltage threshold TVdc. On the other hand, the discharge control start conditions may include the capacitor voltage Vdc being smaller than the capacitor voltage threshold TVdc only for discharge control processes when the power is off.

[0311] <Thirteenth embodiment> In the thirteenth embodiment, it is notified that discharge control is not being performed. The configurations, actions, and effects of the thirteenth embodiment that are not specifically described are the same as those of the sixth embodiment. The thirteenth embodiment will be described mainly focusing on the differences from the sixth embodiment.

[0312] In this embodiment, the flight control processing will be described with reference to the flowchart in Figure 32. The flight control device 40 executes the processing of steps S601 to S614, similar to the sixth and twelfth embodiments. If the eVTOL 10 and an obstacle come abnormally close to each other in steps S605 and S610, the flight control device 40 proceeds to step S1401.

[0313] In step S1401, the flight control device 40 performs a discharge warning process. In the discharge warning process, a warning is issued to an operator or the like that the power supply from the battery 31 to the motor 61 has not been cut off, that voltage is being applied to the inverter high voltage unit 86, that residual power remains in the inverter high voltage unit 86, and so on. Examples of the discharge warning process include displaying a warning on the display that discharge control is not yet complete, turning on a lamp such as a warning light, and emitting a warning sound. The flight control device 40 issues a warning to reliably prevent an operator from getting an electric shock during the period from when the situation calls for discharge control to when discharge control is completed.

[0314] After step S1401, if the forced shutoff process and forced discharge process are completed in steps S606 and S607, the flight control device 40 proceeds to step S1402. In step S1402, the flight control device 40 performs warning termination process. In the warning termination process, processing is performed to terminate the discharge warning process started in step S1401.

[0315] If the inverter lid unit 95 is in the open state in step S609, the flight control device 40 proceeds to step S1403. In step S1403, the flight control device 40 performs discharge warning processing, similar to step S1401. After step S1403, if the interlock cutoff processing and interlock discharge processing are completed in steps S611 and S612, the flight control device 40 proceeds to step S1404. In step S1404, the flight control device 40 performs warning end processing, similar to step S1402.

[0316] If the eVTOL 10 is powered off in step S602, the flight control device 40 proceeds to step S1405. In step S1405, the flight control device 40 performs discharge warning processing, similar to step S1401. After step S1405, if the power-off processing and off-discharge processing are completed in steps S613 and S614, the flight control device 40 proceeds to step S1406. In step S1406, the flight control device 40 performs warning end processing, similar to step S1402.

[0317] If the discharge control in step S607 or the like ends before the discharge of inverter high voltage unit 86 is completed, the warning display continues as long as the conditions for warning display are met, such as when inverter lid unit 95 is in the open state.

[0318] <Fourteenth embodiment> In the fourteenth embodiment, after the power supply to the motor 61 is cut off, processing is performed to restore the power supply to the motor 61. The configurations, actions, and effects not specifically described in the fourteenth embodiment are the same as those of the sixth embodiment. The fourteenth embodiment will be described mainly focusing on the differences from the sixth embodiment.

[0319] In this embodiment, the flight control processing will be described with reference to the flowchart in Figure 33. The flight control device 40 executes the processing of steps S601 to S614, as in the sixth and thirteenth embodiments. After completing the forced shutoff processing and forced discharge processing of steps S606 and S607, the flight control device 40 proceeds to step S1501. In step S1501, the flight control device 40 executes recovery processing. The recovery processing is processing for restoring power supply to the motor 61.

[0320] The return processing will be described with reference to the flowchart in Fig. 34. The flight control device 40 determines whether or not there is a drive request in step S1601 shown in Fig. 34. Examples of cases in which there is a drive request include when the situation in which the eVTOL 10 and an obstacle are abnormally close to each other is resolved, or when an operation to restart the EPU 50 is performed by the pilot or the like.

[0321] If there is a drive request, the flight control device 40 proceeds to step S1602. The flight control device 40 performs EPU confirmation processing in step S1602. The EPU confirmation processing determines whether the EPU 50 is in a state where it can be driven. Examples of EPU confirmation processing include a process for determining whether the detected value of the current sensor is normal, and a process for determining whether the detected value of the voltage sensor is normal. If the detected value of the current sensor is normal, the flight control device 40 determines that it has been confirmed that no short circuit, ground fault, leakage current, etc. has occurred in the P line 111, N line 112, inverter circuit 85, etc.

[0322] In step S1603, the flight control device 40 determines whether or not the EPU 50 is functioning normally. The flight control device 40 determines whether or not the EPU 50 is functioning normally using information such as the current detection value acquired in the EPU confirmation process.

[0323] If the EPU 50 is normal, the flight control device 40 proceeds to step S1604 and performs EPU drive processing. The EPU drive processing involves processing to resume driving the EPU 50. The EPU drive processing includes processing to return the power supply switch 132 from a cut-off state to a power-on state.

[0324] If the EPU 50 is not normal, the flight control device 40 proceeds to step S1605 and performs EPU abnormality processing. EPU abnormality processing includes processing to notify that an abnormality has occurred in the EPU 50 and processing to prevent the EPU 50 from starting to operate. If an abnormal approach between the eVTOL 10 and an obstacle is detected and forced shut-off processing and forced discharge processing for the EPU 50 are still being executed, the EPU 50 cannot be restarted even if the EPU 50 is normal. In contrast, in this embodiment, if there is no abnormality in the EPU 50, operation of the EPU is resumed in order to continue the flight of the eVTOL 10.

[0325] <Fifteenth embodiment> In the fifteenth embodiment, when the power supply to the inverter high voltage section 86 is cut off, the power supply to the inverter low voltage section 87 is cut off. The configurations, actions, and effects not specifically described in the fifteenth embodiment are the same as those of the first embodiment. The fifteenth embodiment will be described mainly focusing on the differences from the first embodiment.

[0326] In this embodiment, the flight control process will be described with reference to the flowchart of Fig. 35. The flight control device 40 executes the processes of steps S101 to S112, similar to the first embodiment.

[0327] After completing the power supply process in step S108, the flight control device 40 proceeds to step S1702, where it determines whether to power off, similar to step S602 in the sixth embodiment. If power is to be turned off, the flight control device 40 proceeds to step S1703, where it performs power-off processing similar to step S613 in the sixth embodiment. Note that the processes of steps S1702 and S1703 may be performed individually for each of the multiple EPUs 50. For example, the flight control device 40 selects an EPU 50 to which power supply is to be cut off in step S1702, and switches the power supply switch 132 of that EPU 50 from the conducting state to the cut-off state in step S1703. After step S103, the flight control device 40 proceeds to step S107.

[0328] After completing the discharge control process in step S107, the flight control device 40 proceeds to step S1701. In step S1701, the flight control device 40 performs a full shutdown process. The full shutdown process is a process for shutting off both the application of the drive voltage and the application of the control voltage to the EPU 50.

[0329] The full shutoff process will be described with reference to the flowchart in Figure 36. In step S1801 shown in Figure 36, the flight control device 40 determines whether or not discharging of the inverter high voltage unit 86 has been completed. For example, the flight control device 40 determines whether or not discharge notification processing has been performed in step S205 of the first embodiment. If discharge notification processing has been performed, the flight control device 40 determines that discharging of the inverter high voltage unit 86 has been completed.

[0330] When the discharge of the inverter high voltage unit 86 is complete, the flight control device 40 proceeds to step S1802. In step S1802, the flight control device 40 determines whether to cut off the control voltage. The control voltage may be cut off when the eVTOL 10 is powered off or when an operation to cut off the control voltage is performed by the pilot or the like. If the control voltage is cut off, the power supply to the inverter low voltage unit 87 is cut off.

[0331] If the control voltage is to be cut off, the flight control device 40 proceeds to step S1803. In step S1803, the flight control device 40 determines whether preparations for cutting off the control voltage are complete. Preparations for cutting off the control voltage include processing such as storing information for performing flight control processing in non-volatile memory such as ROM.

[0332] If preparations for cutting off the control voltage are complete, the flight control device 40 proceeds to step S1804. In step S1804, the flight control device 40 cuts off the control voltage. Processing for cutting off the control voltage includes processing for cutting off the path that connects the battery 31 and the inverter low voltage unit 87 so that electricity can flow between them, processing for stopping the operation of a device that applies the control voltage to the inverter low voltage unit 87, and the like.

[0333] For example, three conditions are assumed for preparation to end control other than discharge control. The first condition is that, if a diagnosis of the propulsion system 30, inverter control unit 81, or flight control device 40 is performed before shutdown, that diagnosis is completed. The second condition is that information required for the next flight or flight history management is transmitted to the flight control device 40 and recorded in memory 43 or transmitted to an external device. The third condition is that a worker such as a pilot performs a forced shutdown operation. Furthermore, if the propulsion device 100 is equipped with multiple inverter devices 80, the control voltage is turned off after it has been confirmed that all of them are ready.

[0334] <Sixteenth embodiment> In the sixteenth embodiment, the voltage of the discharge circuit 141 is detected. The configurations, actions, and effects not specifically described in the sixteenth embodiment are the same as those of the first embodiment. The sixteenth embodiment will be described mainly focusing on the differences from the first embodiment.

[0335] As shown in FIG. 37 , in the EPU 50, one motor 61 is driven by one inverter device 80. The inverter device 80 has a discharge voltage sensor 155. The discharge voltage sensor 155 is a sensor that detects the voltage of the discharge circuit 141. The discharge voltage sensor 155 is communicatively connected to the flight control device 40.

[0336] In this embodiment, a plurality of voltage sensors, such as voltage sensors 151, 152, and 155, are provided in the high-voltage DC path for one inverter device 80. Also, in the seventh embodiment, a common battery 31 is connected to a plurality of inverter devices 80, and a voltage sensor 152 is provided in the high-voltage DC path of each inverter device 80. In such a configuration in which a plurality of voltage sensors are provided, the flight control device 40 or the like may diagnose the normality or abnormality of the power supply system or voltage sensor by comparing the values ​​of the respective voltage sensors with each other.

[0337] When the power supply switch 132 is in the on state, each voltage sensor should output a voltage value equivalent to the battery voltage. On the other hand, when the power supply switch 132 is in the off state, the voltage sensor on the battery side of the power supply switch 132 should indicate a voltage equivalent to the battery voltage. Furthermore, when the power supply switch 132 is in the off state, the voltage sensor in the inverter device 80 should indicate a voltage lower than the battery voltage. When the power supply switch 132 is switched from one of the on state and the off state to the other, the voltage sensor in the inverter device 80 should indicate a change in voltage value in accordance with the switching of the power supply switch 132. Furthermore, during discharge control, the voltage sensor in the inverter device 80 should indicate a decrease in voltage as the discharge control progresses.

[0338] Therefore, by comparing the outputs of multiple voltage sensors that should show similar voltages and voltage changes, it becomes possible to accurately detect abnormalities in the propulsion system 30, the EPU 50, etc.

[0339] Furthermore, if an instruction to end the discharge control is received during the discharge control, the discharge control may be ended even if the discharge is not completed. Examples of cases in which an instruction to end the discharge control is received during the discharge control include when a reflight command is received during the discharge control or when an instruction to forcibly shut off the power is received by an operator.

[0340] <Other embodiments> The disclosure of this specification is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and elements shown in the embodiments, and can be implemented in various modifications. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and elements from the embodiments. The disclosure encompasses the substitution or combination of parts and elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope is defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0341] In each of the above embodiments, a housing lid such as the inverter lid 95 may be provided on at least one of the motor housing 70 and the inverter housing 90. In this case, at least one of the motor housing 70 and the inverter housing 90 corresponds to the drive housing. For example, the housing lid may be provided on the motor housing 70. In this configuration, the housing lid covers the opening of the motor housing 70 to hide the motor high-voltage section. The motor high-voltage section is a portion or component of the motor device 60 to which a drive voltage is applied, and corresponds to the drive voltage section. Examples of the motor high-voltage section include coil components that form the motor coil and bus bar components that are electrically connected to the coil components. It is preferable that a discharge circuit 141 is electrically connected to the motor high-voltage section via a first selection switch 142.

[0342] In each of the above embodiments, the flight control device 40 may be configured in any way to detect the opening of the inverter lid unit 95. For example, the flight control device 40 may detect that the inverter lid unit 95 has been opened using a detection signal from a lid sensor. The lid sensor may be formed to include a contact sensor, similar to the lid detection circuit 120, or may be formed to include a non-contact sensor. Furthermore, a signal indicating that the inverter lid unit 95 has been opened may be input to the flight control device 40 by an operator performing an input operation, for example.

[0343] In each of the above embodiments, in addition to the discharge duration, the discharge current, the residual voltage, etc. may be used as a parameter for completing the discharge of inverter high voltage unit 86. For example, in the first embodiment, after the discharge of inverter high voltage unit 86 is started by the d-axis drive process, the d-axis drive stop process may be performed when the discharge current or the residual voltage becomes small enough to be reduced to a reference value.

[0344] In each of the above embodiments, the control mode may be changed at any timing. For example, when the eVTOL 10 is flying, the control mode may be changed to the interlock release mode or the interlock mode when predetermined conditions are met regarding the pilot's operation, the flight state of the eVTOL 10, etc. Also, when the eVTOL 10 is on the ground, the control mode may be changed to the interlock mode or the interlock release mode when predetermined conditions are met regarding the pilot's operation, the flight state of the eVTOL 10, etc. Furthermore, the control mode may be set to the interlock mode when the eVTOL 10 is powered on.

[0345] In each of the above embodiments, the residual power of inverter high voltage unit 86 may be discharged in any manner. For example, in the above second embodiment, inverter high voltage unit 86 may be discharged by both motor 61 and discharge circuit 141. In this configuration, first selection switch 142 can connect both motor 61 and discharge circuit 141 to inverter circuit 85. This makes it possible to further shorten the time required for discharging inverter high voltage unit 86 by both motor 61 and discharge circuit 141.

[0346] In each of the above embodiments, the discharge switch such as the first selection switch 142 may be provided in any manner as long as it enables discharge of the inverter high voltage unit 86. For example, the discharge switch may be connected in series to the discharge circuit 141.

[0347] As shown in Figure 14, in a configuration in which the propulsion system 30 is provided with a third selection switch 144 as a discharge switch, the third selection switch 144 and a discharge circuit 141 are connected in series between the P line 111 and the N line 112. In this configuration, the third selection switch 144 and the discharge circuit 141 are connected in parallel to the smoothing capacitor 114 and the inverter high voltage unit 86. The third selection switch 144 can be switched between a conductive state and a cut-off state. When the third selection switch 144 is in the conductive state, the discharge circuit 141 can discharge the inverter high voltage unit 86 and the smoothing capacitor 114.

[0348] Furthermore, in this configuration, the flight control device 40 switches the power supply switch 132 to the disconnected state during the circuit discharge process, and then switches the third selection switch 144 to the conducting state. As a result, a discharge current flows from the inverter high voltage unit 86 to the discharge circuit 141 via the third selection switch 144, thereby discharging the inverter high voltage unit 86. In other words, the residual power in the smoothing capacitor 114 is discharged to the discharge circuit 141 via the third selection switch 144. Preferably, the flight control device 40 is configured to determine whether the power supply switch 132 is in the disconnected state, and switch the third selection switch 144 to the conducting state only when it is determined that the power supply switch 132 is in the disconnected state.

[0349] In each of the above embodiments, the flight control device 40 may perform partial upper-on processing in addition to or instead of upper-on processing. In partial upper-on processing, processing is performed to place the inverter circuit 85 in a partial upper-on state. In the partial upper-on state, the upper arm switches 116 are turned on in at least one phase, and the upper arm switches 116 of the remaining phases are turned off. In the partial upper-on state, the lower arm switches 117 are turned off in all phases. The partial upper-on state corresponds to the upper energized state.

[0350] Furthermore, the flight control device 40 may perform partial bottom on processing in addition to or instead of the bottom on processing. In the partial bottom on processing, processing is performed to set the inverter circuit 85 to a partial bottom on state. In the partial bottom on state, the lower arm switches 117 are turned on in at least one phase, and the lower arm switches 117 of the remaining phases are turned off. In the partial bottom on state, the upper arm switches 116 are turned off in all phases. The partial bottom on state corresponds to a bottom energized state.

[0351] The flight control device 40 may alternately and repeatedly perform a partial-up-on process and a partial-down-on process, just as it alternately and repeatedly performs an upper-on process and a lower-on process. That is, the flight control device 40 may repeatedly transition the inverter circuit 85 between a partial-up-on state and a partial-down-on state.

[0352] When repeatedly transitioning the inverter circuit 85 between the partial-up on state and the partial-down on state, the flight control device 40 may variably set the phase to be transitioned to the on state. For example, when executing the partial-up on process and the partial-down on process as a set, the flight control device 40 may transition a phase to the on state in the current set that is different from the phase transitioned to the on state in the previous set.

[0353] However, it is preferable that the flight control device 40 repeats the partial top-on process and the partial bottom-on process so as not to flow current to the motor 61. For example, the flight control device 40 prevents the overlap between the top-on period during which the upper arm switch 116 is in the on state in the partial top-on process of the previous set and the bottom-on period during which the lower arm switch 117 is in the on state in the partial bottom-on process of the current set. If the top-on period and the bottom-on period overlap, there is a concern that current will flow to the motor 61 through the upper arm switch 116 of one phase and the lower arm switch 117 of another phase during the overlapping period. In contrast, if the top-on period and the bottom-on period do not overlap, current will not flow to the motor 61 through the upper arm switch 116 of one phase and the lower arm switch 117 of another phase.

[0354] Furthermore, when repeatedly transitioning the inverter circuit 85 between the partial-upper-ON state and the partial-lower-ON state, the flight control device 40 may variably set the number of phases to be transitioned to the ON state. The flight control device 40 may transition a different number of phases to the ON state in a current set than the number of phases transitioned to the ON state in the previous set. For example, the flight control device 40 may gradually decrease the number of phases to be transitioned to the ON state in the partial-upper-ON state or the partial-lower-ON state. For example, the flight control device 40 may repeatedly execute the upper-ON process and the lower-ON process when the capacitor voltage Vdc is higher than a predetermined voltage, and repeatedly execute the partial-upper-ON process and the partial-lower-ON process when the capacitor voltage Vdc falls below the predetermined voltage.

[0355] In each of the above embodiments, at least a part of the programs stored in the memories 43 and 83 may be rewritten via wireless communication such as OTA, which stands for Over the Air.

[0356] In each of the above embodiments, flight control processing may be performed by at least one of the inverter control unit 81 and the flight control device 40. The propulsion control program may be included in at least one of the programs 44 and 84. Furthermore, at least one processing unit that executes the propulsion control program may include at least one of the processors 42 and 82.

[0357] In each of the above embodiments, the vertical take-off and landing aircraft on which the flight control device 40 is mounted may be an electrically operated vertical take-off and landing aircraft in which at least one EPU 50 drives at least one propeller 20. For example, a configuration in which one propeller 20 is driven by multiple EPUs 50, or a configuration in which one EPU 50 drives multiple propellers 20, may also be used.

[0358] In each of the above embodiments, the air vehicle on which the EPU 50 is mounted does not have to be a vertical take-off and landing aircraft as long as it is electrically powered. For example, the air vehicle may be an electric aircraft capable of take-off and landing with a taxiing motion. Furthermore, the air vehicle may be a rotary-wing aircraft or a fixed-wing aircraft. The air vehicle may also be an unmanned air vehicle without a crew member on board. The unmanned air vehicle may or may not have a crew cabin 14. Furthermore, a pilot may remotely control the air vehicle.

[0359] In each of the above embodiments, the moving body on which the EPU 50 is mounted does not have to be an aircraft as long as it can move by rotation of a rotating body. For example, the moving body may be a vehicle, a ship, a construction machine, or an agricultural machine. For example, if the moving body is a vehicle or a construction machine, the rotating body may be a wheel for movement, and the output shaft may be an axle. If the moving body is a ship, the rotating body may be a screw propeller for propulsion, and the output shaft may be a propeller shaft.

[0360] In each of the above embodiments, the flight control device 40 and the inverter control unit 81 are provided by a control system including at least one computer. The control system includes at least one processor that is hardware. If this processor is referred to as a hardware processor, the hardware processor can be provided by the following (i), (ii), or (iii).

[0361] (i) A hardware processor may be a hardware logic circuit. In this case, the computer is implemented by a digital circuit including a large number of programmed logic units (gate circuits). The digital circuit may include a memory that stores at least one of a program and data. The computer may be implemented by an analog circuit. The computer may be implemented by a combination of a digital circuit and an analog circuit.

[0362] (ii) The hardware processor may be at least one processor core that executes a program stored in at least one memory. In this case, a computer is provided by at least one memory and at least one processor core. The processor core is referred to as a CPU, for example. The memory is also referred to as a storage medium. The memory is a non-transitory, tangible storage medium that non-temporarily stores "at least one of a program and data" that can be read by the processor.

[0363] (iii) The hardware processor may be a combination of (i) above and (ii) above, where (i) and (ii) are located on different chips or on a common chip.

[0364] That is, at least one of the means and functions provided by the flight control device 40 and the inverter control unit 81 can be provided by hardware only, software only, or a combination thereof.

[0365] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0366] (Technical thought 1) A propulsion system (30) for propelling an air vehicle (10), comprising: a motor (61) that drives the flying object using power supplied from a power supply unit (31) to propel the flying object; a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) that houses the drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and that covers the opening so as to hide the drive voltage unit; an interlock unit (S104, S608) that sets, as a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode for cutting off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened; an interlock release unit (S111, S604) that releases the interlock mode when the flying object is in flight; A propulsion system comprising:

[0367] (Technical thought 2) The interlock release unit is The propulsion system described in Technical Idea 1, wherein the interlock mode is released by setting the control mode to a continuous mode in which power supply from the power supply unit to the motor continues even when the housing lid unit is opened.

[0368] (Technical Thought 3) The propulsion system described in Technical Idea 1 or 2, wherein the interlock release unit releases the interlock mode in conjunction with the takeoff of the aircraft.

[0369] (Technical Thought 4) The propulsion system according to any one of Technical Ideas 1 to 3, wherein the interlock unit sets the interlock mode in accordance with the landing of the flying object.

[0370] (Technical Thought 5) The propulsion system according to any one of Technical Ideas 1 to 4, wherein the interlock unit maintains the interlock mode when the flying object is on the ground.

[0371] (Technical Thought 6) A propulsion system described in any one of technical ideas 1 to 5, comprising a discharge execution unit (S107, S612) that discharges the drive voltage unit when the control mode is in the interlock mode and the power supply from the power supply unit to the motor is cut off due to the opening of the housing lid unit.

[0372] (Technical Thought 7) The discharge execution unit The propulsion system according to Technical Idea 6, further comprising a motor discharge unit (S201, S401, S402, S501) that discharges residual power of the drive voltage unit to the motor.

[0373] (Technical Thought 8) The discharge execution unit The propulsion system according to Technical Idea 6 or 7, further comprising a stop discharge unit (S201, S401, S402) that discharges the residual power of the drive voltage unit to the motor so that the propeller (20) of the aircraft does not rotate.

[0374] (Technical Thought 9) The discharge execution unit A propulsion system according to any one of Technical Ideas 6 to 8, comprising a rotary discharge unit (S501) that discharges residual power from the drive voltage unit to the motor so that the propeller (20) of the aircraft rotates.

[0375] (Technical Thought 10) The discharge execution unit The propulsion system according to any one of Technical Ideas 6 to 9, further comprising a circuit discharge unit (S301) that discharges residual power of the drive voltage to a discharge circuit (141) different from the motor.

[0376] (Technical Thought 11) a power conversion unit (85, 851, 852) having a switch element (116, 117) included in the drive voltage unit, and converting the power supplied from the power supply unit to the motor by switching the switch element; a smoothing capacitor (114) included in the drive voltage unit and connected to the power conversion unit in a conductive manner; Equipped with The discharge execution unit A propulsion system described in any one of Technical Ideas 6 to 10, having a conversion discharge unit (S701 to S711, S801 to S809) that operates the switch element so that the residual power of the smoothing capacitor is discharged to the power conversion unit.

[0377] (Technical Thought 12) The power conversion unit and upper and lower arm circuits (115) each provided for a plurality of phases, each of which includes an upper arm switch (116) as the switching element and a lower arm switch (117) as the switching element different from the upper arm switch, The conversion and discharge unit A propulsion system as described in Technical Idea 11, which has a conversion transition unit (S701 to S709, S801 to S807) that repeatedly transitions the power conversion unit between an upper current state in which the upper arm switch is in a current-on state and the lower arm switch is in a cut-off state in each of the upper and lower arm circuits of multiple phases, and a lower current state in which the lower arm switch is in a cut-off state and the upper arm switch is in a current-on state in each of the upper and lower arm circuits of multiple phases.

[0378] (Technical Thought 13) The conversion and discharge unit A propulsion system as described in Technical Idea 12, which has a maintenance setting unit (1201-1210) that sets an upper maintenance period (JTH) during which the upper power state is maintained and a lower maintenance period (JTL) during which the lower power state is maintained according to the state of the power conversion unit when the conversion transition unit repeatedly transitions the power conversion unit between the upper power state and the lower power state.

[0379] (Technical Thought 14) The conversion and discharge unit an upper shortening unit (S1101, 1205) that, when the conversion transition unit repeatedly transitions the power conversion unit to the upper power-on state, makes a period (JTH_n+1) during which the next upper power-on state is maintained shorter than a period (JTH_n) during which the current upper power-on state is maintained; a lower shortening unit (S1102, 1210) that, when the conversion transition unit repeatedly transitions the power conversion unit to the lower power conduction state, makes a period (JTL_n+1) during which the next lower power conduction state is maintained shorter than a period (JTL_n) during which the current lower power conduction state is maintained; 14. A propulsion system according to technical idea 12 or 13, comprising:

[0380] (Technical Thought 15) a first conversion unit (851) that is the power conversion unit and is connected to the motor so as to be electrically connected; a second conversion unit (852) that is the power conversion unit different from the first conversion unit and is connected in parallel to the first conversion unit so as to be electrically connected to the motor; Equipped with The conversion and discharge unit includes: a first transition unit (S802) that repeatedly transitions the first conversion unit between the upper current conduction state and the lower current conduction state; a second transition unit (S803) that repeatedly transitions the second conversion unit between the upper current conduction state and the lower current conduction state; a timing shifting unit (S801, S806, S807) that shifts the timing at which the first conversion unit transitions from one of the upper current conduction state and the lower current conduction state to the other and the timing at which the second conversion unit transitions from one of the upper current conduction state and the lower current conduction state to the other; 15. A propulsion system according to any one of Technical Ideas 12 to 14, which has the above features.

[0381] (Technical Thought 16) The conversion transition unit an upper maintaining unit (S702 to S704) that maintains the power conversion unit in the upper conducting state so that residual power of the smoothing capacitor is stored in the parasitic capacitance (117b) of the lower arm switch and so that power stored in the parasitic capacitance (116b) of the upper arm switch is discharged to the upper arm switch; a lower maintaining unit (705 to S707) that maintains the power conversion unit in the lower energized state so that residual power in the smoothing capacitor is stored in the parasitic capacitance of the upper arm switch and so that power stored in the parasitic capacitance of the lower arm switch is discharged to the lower arm switch; 16. A propulsion system according to any one of Technical Ideas 12 to 15, having the above.

[0382] (Technical Thought 17) The discharge execution unit an off-discharge unit (S614) for discharging the residual power of the driving voltage unit when the aircraft is powered off; an interlock discharge unit (S612) that discharges residual power of the driving voltage unit more rapidly than the discharge by the off discharge unit when the control mode is the interlock mode and the power supply from the power supply unit to the motor is cut off as the housing lid unit is opened; The propulsion system according to technical idea 6,

[0383] (Technical Thought 18) a motor (61) that drives the flying object (10) using power supplied from the power supply unit (31); a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) that houses the drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and that covers the opening so as to hide the drive voltage unit; A propulsion control device (40) for controlling a propulsion system (30) having: an interlock unit (S104, S608) that sets, as a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode for cutting off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened; an interlock release unit (S111, S604) that releases the interlock mode when the flying object is in flight; A propulsion control device comprising:

[0384] (Technical Thought 19) a motor (61) that drives the flying object (10) using power supplied from the power supply unit (31); a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) that houses the drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and that covers the opening so as to hide the drive voltage unit; a propulsion control program (44) for controlling a propulsion system (30) having: At least one processing section (42) As a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode is set to cut off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened (S104, S608); A propulsion control program that releases the interlock mode when the flying object is in flight (S111, S604). [Explanation of symbols]

[0385] 10...eVTOL as an aircraft, 20...propeller, 30...propulsion system, 31...battery as power supply unit, 40...flight control device as propulsion control device, 42...processor as processing unit, 44...program as propulsion control program, 61...motor, 85...inverter circuit as power conversion unit, 851...first inverter circuit as power conversion unit and first conversion unit, 852...second inverter circuit as power conversion unit and second conversion unit, 86...inverter high voltage unit as drive voltage unit, 90...inverter housing as drive housing, 92...inverter opening as opening, 95...inverter lid as housing lid, 114...smoothing capacitor, 115...upper and lower arm circuits, 116...upper arm switch as switch element, 116b...upper parasitic capacitance as parasitic capacitance, 117...lower arm switch as switch element, 117b...lower parasitic capacitance as parasitic capacitance, 141...discharge circuit, JTH...upper on threshold as upper maintenance period, JTL...lower on threshold as lower maintenance period.

Claims

1. A propulsion system (30) for propelling an air vehicle (10), comprising: a motor (61) that is driven by power supplied from a power supply unit (31) to propel the flying object; a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) containing the drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and covers the opening so as to hide the drive voltage unit; an interlock unit (S104, S608) that sets, as a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode for cutting off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened; an interlock release unit (S111, S604) that releases the interlock mode when the flying object is in flight; A propulsion system comprising:

2. The interlock release unit is 2. The propulsion system according to claim 1, wherein the interlock mode is released by setting the control mode to a continuous mode in which power supply to the motor continues even when the housing lid is opened.

3. The propulsion system according to claim 1 or 2, wherein the interlock release unit releases the interlock mode in response to takeoff of the aircraft.

4. The propulsion system according to claim 1 or 2, wherein the interlock unit sets the interlock mode in accordance with landing of the flying object.

5. The propulsion system according to claim 1 or 2, wherein the interlock unit maintains the interlock mode when the flying vehicle is on the ground.

6. 3. The propulsion system according to claim 1, further comprising a discharge execution unit (S107, S612) that discharges the drive voltage unit when the control mode is the interlock mode and the power supply from the power supply unit to the motor is cut off as the housing lid is opened.

7. The discharge execution unit 7. A propulsion system according to claim 6, further comprising a motor discharge unit (S201, S401, S402, S501) that discharges residual power from the drive voltage unit to the motor.

8. The discharge execution unit 7. The propulsion system according to claim 6, further comprising a stop discharge unit (S201, S401, S402) that discharges residual power from the drive voltage unit to the motor so that the propeller (20) of the flying vehicle does not rotate.

9. The discharge execution unit 7. The propulsion system according to claim 6, further comprising a rotation discharge unit (S501) that discharges residual power from the drive voltage unit to the motor so that the propeller (20) of the flying vehicle rotates.

10. The discharge execution unit 7. The propulsion system according to claim 6, further comprising a circuit discharge unit (S301) that discharges the residual power of the drive voltage to a discharge circuit (141) separate from the motor.

11. a power conversion unit (85, 851, 852) having a switch element (116, 117) included in the drive voltage unit, and converting the power supplied from the power supply unit to the motor by switching the switch element; a smoothing capacitor (114) included in the drive voltage unit and connected to the power conversion unit in a conductive manner; Equipped with The discharge execution unit 7. The propulsion system according to claim 6, further comprising a conversion / discharge unit (S701 to S711, S801 to S809) that operates the switch element so that residual power in the smoothing capacitor is discharged to the power conversion unit.

12. The power conversion unit The inverter includes an upper arm switch (116) as the switching element and a lower arm switch (117) as the switching element different from the upper arm switch, and has upper and lower arm circuits (115) provided for each of a plurality of phases, The conversion and discharge unit The propulsion system according to claim 11, further comprising a conversion transition unit (S701 to S709, S801 to S807) that repeatedly transitions the power conversion unit between an upper current state in which the upper arm switches are in a current-on state and the lower arm switches are in a cut-off state in each of the upper and lower arm circuits of multiple phases, and a lower current state in which the lower arm switches are in a cut-off state and the upper arm switches are in a current-on state in each of the upper and lower arm circuits of multiple phases.

13. The conversion and discharge unit A propulsion system as described in claim 12, further comprising a maintenance setting unit (1201 to 1210) that sets an upper maintenance period (JTH) during which the upper current state is maintained and a lower maintenance period (JTL) during which the lower current state is maintained according to the state of the power conversion unit when the conversion transition unit repeatedly transitions the power conversion unit between the upper current state and the lower current state.

14. The conversion and discharge unit an upper shortening unit (S1101, 1205) that, when the conversion transition unit repeatedly transitions the power conversion unit to the upper current conduction state, sets a period (JTH_n+1) during which the next upper current conduction state is maintained shorter than a period (JTH_n) during which the current upper current conduction state is maintained; a lower shortening unit (S1102, 1210) that, when the conversion transition unit repeatedly transitions the power conversion unit to the lower current conduction state, makes a period (JTL_n+1) during which the next lower current conduction state is maintained shorter than a period (JTL_n) during which the current lower current conduction state is maintained; 13. The propulsion system of claim 12, comprising:

15. a first conversion unit (851) that is the power conversion unit and is connected to the motor so as to be electrically connected; a second conversion unit (852) that is the power conversion unit different from the first conversion unit and is connected to the motor so as to be connected in parallel to the first conversion unit; Equipped with The conversion and discharge unit a first transition unit (S802) that repeatedly transitions the first conversion unit between the upper current conduction state and the lower current conduction state; a second transition unit (S803) that repeatedly transitions the second conversion unit between the upper current conduction state and the lower current conduction state; a timing shifting unit (S801, S806, S807) that shifts the timing at which the first conversion unit transitions from one of the upper current conduction state and the lower current conduction state to the other and the timing at which the second conversion unit transitions from one of the upper current conduction state and the lower current conduction state to the other; 13. The propulsion system of claim 12, comprising:

16. The conversion transition unit an upper maintaining unit (S702 to S704) that maintains the power conversion unit in the upper conducting state so that residual power in the smoothing capacitor is stored in the parasitic capacitance (117b) of the lower arm switch and so that power stored in the parasitic capacitance (116b) of the upper arm switch is discharged to the upper arm switch; a lower maintaining unit (705 to S707) that maintains the power conversion unit in the lower energized state so that residual power in the smoothing capacitor is stored in the parasitic capacitance of the upper arm switch and so that power stored in the parasitic capacitance of the lower arm switch is discharged to the lower arm switch; 13. The propulsion system of claim 12, comprising:

17. The discharge execution unit an off-discharge unit (S614) for discharging the residual power of the driving voltage unit when the flying object is powered off; an interlock discharge unit (S612) that, when the control mode is the interlock mode and the power supply from the power supply unit to the motor is cut off as the housing lid is opened, discharges the residual power of the drive voltage unit more rapidly than the discharge by the off discharge unit; 7. The propulsion system of claim 6, further comprising:

18. a motor (61) that drives the flying object (10) using power supplied from the power supply unit (31); a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) containing the drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and covers the opening so as to hide the drive voltage unit; A propulsion control device (40) for controlling a propulsion system (30) having: an interlock unit (S104, S608) that sets, as a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode for cutting off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened; an interlock release unit (S111, S604) that releases the interlock mode when the flying object is in flight; A propulsion control device comprising:

19. a motor (61) that drives the flying object (10) using power supplied from the power supply unit (31); a drive voltage section (86) to which a drive voltage for driving the motor is applied in response to the supply of power from the power supply section to the motor; a drive housing (90) containing the drive voltage section; a housing lid (95) that is provided to be able to open an opening (92) of the drive housing and covers the opening so as to hide the drive voltage unit; A propulsion control program (44) for controlling a propulsion system (30) having: At least one processing section (42) As a control mode for controlling the power supply from the power supply unit to the motor, an interlock mode is set to cut off the power supply from the power supply unit to the motor so that application of the drive voltage to the drive voltage unit is stopped when the housing lid is opened (S104, S608). A propulsion control program that releases the interlock mode when the flying object is in flight (S111, S604).

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