Multicopter

Abstract

To provide a multicopter mounted with a power generator driven by an engine and a chargeable / dischargeable battery, in which overheat of the battery is suppressed and electric power is stably supplied from the battery to motors.SOLUTION: A multicopter 1 includes a plurality of rotors 25 driven by motors 24, a chargeable / dischargeable battery 31, a power generator 42 driven by an engine 41, and a controller 33 for controlling the operation of the engine 41 and the electric power supply between the power generator 42, the battery 31 and the motors 24. The controller 33 supplies generated electric power from the power generator 42 to the motors 24 to satisfy flight electric power, and discharges battery electric power from the battery 31 to the motors 24 to supplement insufficient electric power. When a battery temperature becomes equal to or higher than a determination temperature, the controller determines that there is a possibility of overheat of the battery 31, increases a power generation load of the power generator 42 to increase the generated electric power from the power generator 42 to the motors 24, and reduces a discharge load of the battery 31 to reduce the battery electric power from the battery 31 to the motors 24.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a multicopter that is equipped with an engine-driven generator and a rechargeable battery, and flies by supplying power to a motor to rotate multiple rotors. [Background technology]

[0002] Conventionally, as this type of technology, for example, a multicopter described in Patent Document 1 below is known. This multicopter includes a main body, a plurality of arms extending from the main body in the direction of the half system, and a propeller (rotor) provided near the tip of each arm. The multicopter further includes a device (FCU) for controlling the flight, a device (PMU) for managing the power supplied to the FCU, a first battery for supplying power to the FCU via the PMU, and a lift generating system provided for each arm. In addition to the rotor, each lift generating system includes a motor for rotating the rotor, a device (ESC) for controlling the rotation speed of the motor, and a second battery for supplying power to the motor via the ESC. When a malfunction such as a power drop occurs in the second battery of any of the plurality of lift generating systems, the FCU electrically disconnects the ESC that has been supplied with power from the second battery with the malfunction from the second battery, and controls a switching circuit to connect the ESC to a second battery that is not malfunctioning and is provided in another lift generating system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-93724 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a failure occurs in a power supply source such as a battery during flight of a multicopter, it is required to continue the flight and then land safely. Here, in the multicopter described in Patent Document 1, a plurality of independent second batteries are mounted as a fail-safe against a failure of the second battery, and the power supply from the second battery having a failure is switched to the power supply from another second battery having no failure, thereby dealing with the failure of the second battery and enabling the multicopter to continue flying. However, in the multicopter described in Patent Document 1, when the power supply from the second battery having a failure is switched to the power supply from the other second battery having no failure, the power supply to the corresponding motor is stopped instantaneously. As a result, the rotation of the rotor becomes unstable, and there is a risk that it may be difficult to continue the safe flight and land safely of the multicopter.

[0005] Here, battery malfunctions include excessive temperature rise (overheating) of the battery. The temperature of the battery rises due to the heat of chemical reactions and Joule heat caused by internal resistance. In a multicopter, if battery overheating can be suppressed, battery malfunctions can be reduced. As a result, it is possible to install multiple batteries in a multicopter and eliminate the need to switch from one battery to another.

[0006] This disclosed technology has been made in consideration of the above circumstances, and its purpose is to prevent the battery from overheating and stably supply power from the battery to the motor in a multicopter that is equipped with an engine-driven generator and a chargeable and dischargeable battery to supply power to the motor. [Means for solving the problem]

[0007] In order to achieve the above object, the technology described in claim 1 includes a plurality of rotors, a motor for rotating and driving each rotor, a battery configured to be able to charge and discharge power supplied to the motor, a generator for generating power supplied to the motor and power charged to the battery, an engine for driving the generator, and control means for controlling operation of the engine, supply of power from the generator to the motor, charging of the battery from the generator, and discharging from the battery to the motor, and further including battery temperature detection means for detecting the temperature of the battery in a multicopter that flies by supplying power to the motor to rotate each rotor, and the control means is configured to supply generated power from the generator to the motor in order to satisfy flight power required for the multicopter to fly, and to discharge battery power from the battery to the motor in order to make up for power that is insufficient with the generated power alone, and when the temperature of the battery detected by the battery temperature detection means becomes equal to or higher than a predetermined judgment temperature, the control means increases the generation load of the generator in order to increase the generated power supplied from the generator to the motor, and reduces the discharge load of the battery in order to reduce the battery power discharged from the battery to the motor. When the temperature of the battery detected by the battery temperature detection means becomes equal to or higher than the judgment temperature and then falls to or below a predetermined return temperature, the control means reduces the power generation load of the generator to return to a state before the power generation supplied from the generator to the motor is increased, and increases the discharge load of the battery to return to a state before the battery power discharged from the battery to the motor is reduced. The purpose of this is to

[0008] According to the configuration of the above technology, the multicopter flies by supplying power to the motor to rotate each rotor. Here, the control means controls the operation of the engine, the supply of power from the generator to the motor, charging from the generator to the battery, and discharging from the battery to the motor. Then, in order to satisfy the flight power required for the flight of the multicopter, the control means supplies generated power from the generator to the motor and discharges battery power from the battery to the motor to make up for power that is insufficient with only the generated power. Also, when the temperature of the battery detected by the battery temperature detection means becomes equal to or higher than a predetermined judgment temperature, the control means increases the power generation load of the generator to increase the generated power supplied from the generator to the motor and reduces the discharge load of the battery to reduce the battery power discharged from the battery to the motor. Therefore, when the temperature of the battery becomes equal to or higher than the predetermined judgment temperature and the battery is about to overheat, the generated power supplied from the generator to the motor increases, and instead the battery power borne by the battery decreases, so that the current charged from the generator to the battery and the current discharged from the battery to the motor are suppressed. Furthermore, when the battery temperature drops below a predetermined return temperature after reaching a predetermined threshold temperature, the generator power generation load is reduced to return to the state before the power generation supplied from the generator to the motor was increased, and the battery discharge load is increased to return to the state before the battery power discharged from the battery to the motor was reduced, and therefore the operating load of the engine that drives the generator is reduced to the original state.

[0009] In order to achieve the above object, the technology recited in claim 2 is the technology recited in claim 1, wherein when the control means reduces the discharge load of the battery, the battery current discharged from the battery to the motor is reduced so that it falls within a predetermined range value.

[0010] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1, the battery current discharged from the battery to the motor is reduced to fall within a predetermined range value, so some fluctuation in the reduction of the battery current is allowed.

[0011] In order to achieve the above object, the technology described in claim 3 is the technology described in claim 1 or 2, in which the control means increases the engine speed to increase the generator speed in order to increase the power generation load of the generator.

[0012] According to the configuration of the above technology, the rotation speed of the generator is increased by the engine to increase the power generation load of the generator, thereby achieving the same effect as the technology described in claim 1 or 2.

[0013] In order to achieve the above object, the technology recited in claim 4 is the technology recited in any one of claims 1 to 3, wherein the control means increases the power generation load of the generator stepwise at predetermined time intervals when increasing the power generation load of the generator.

[0014] According to the configuration of the above technology, in addition to the effect of the technology described in any one of claims 1 to 3, the power generation load of the generator is increased stepwise at predetermined time intervals, thereby suppressing sudden changes in the operation of the generator.

[0015] In order to achieve the above object, the technology recited in claim 5 is the technology recited in claim 4, wherein the control means, when reducing the discharge load of the battery, reduces the load stepwise at predetermined time intervals in accordance with a stepwise increase in the power generation load.

[0016] According to the configuration of the above technology, in addition to the effect of the technology described in claim 4, the battery discharge load is gradually reduced at predetermined time intervals in accordance with the gradual increase in the power generation load, thereby suppressing sudden changes in the battery discharge load. Effect of the Invention

[0017] According to the technology described in claim 1, in a multicopter equipped with an engine-driven generator and a rechargeable battery to supply power to the motor, overheating of the battery can be prevented, and power can be stably supplied from the battery to the motor. In addition, it is possible to prevent the engine fuel economy from deteriorating more than necessary.

[0018] According to the technology described in claim 2, in addition to the effect of the technology described in claim 1, sudden movements due to variations in the responsiveness of generators, etc. and the flight behavior of the multicopter are eliminated, thereby realizing stable power supply operation.

[0019] According to the technique recited in claim 3, it is possible to obtain an effect equivalent to that of the technique recited in claim 1 or 2.

[0020] According to the technique recited in claim 4, in addition to the effect of the technique recited in any one of claims 1 to 3, it is possible to operate a battery or the like stably.

[0021] According to the technique recited in claim 5, it is possible to obtain the same effect as the technique recited in claim 4. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing an appearance of a multicopter according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a multicopter according to one embodiment. [Diagram 3] FIG. 1 is a schematic diagram showing a generator engine system and some of its associated devices in one embodiment. [Figure 4] 1 is a graph showing the relationship between the engine speed and power generation current during flight of a multicopter according to one embodiment, and an iso-fuel consumption rate line, iso-output line, full-throttle engine performance line, iso-voltage line, and operating line. [Diagram 5] 5 is a flowchart showing the contents of power supply control in one embodiment. [Figure 6] 5 is a time chart showing the behavior of various parameters related to power supply control when the multicopter is in steady flight in one embodiment. [Figure 7] 10 is a time chart showing the behavior of various parameters related to power supply control when the multicopter increases its cruising speed or altitude during steady flight in one embodiment. [Figure 8] 10 is a time chart showing the behavior of various parameters related to power supply control when the multicopter encounters a headwind during steady flight in one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of a multicopter will be described in detail with reference to the drawings.

[0024] [About the multicopter configuration, etc.] Fig. 1 is a perspective view showing the appearance of a multicopter 1 according to this embodiment. Fig. 2 is a block diagram showing the configuration of the multicopter 1. The configuration of the multicopter 1 will be described in detail below with reference to Figs. 1 and 2.

[0025] A multicopter is a type of helicopter, and is a rotary wing aircraft equipped with three or more rotors. The multicopter 1 of this embodiment includes an airframe 11 and an engine generator unit 12. The airframe 11 includes a plurality of arms 21 (four in this embodiment) with bifurcated tips, an arm base 22 that radially supports the plurality of arms 21 in a cantilever manner, an airframe base 23 that supports the arm base 22, a plurality of motors 24 (eight in this embodiment) provided at the tips of the arms 21, and a plurality of rotors 25 (eight in this embodiment) that are rotationally driven by the motors 24. This multicopter 1 is configured to fly by simultaneously rotating the plurality of rotors 25 by the corresponding motors 24.

[0026] The arm base 22 is provided on the aircraft base 23. A battery 31, a fuel tank 32, a main controller 33, a flight controller 34, a power control unit 35, an electric speed controller 36, etc. are provided inside the arm base 22. The arm base 22 also has an imaging unit 37 that captures or records images of the outside. The imaging unit 37 includes a camera, a recording memory, etc.

[0027] The engine generator unit 12 is suspended below the aircraft base 23. The engine generator unit 12 includes a power generating engine system 15 (including an engine 41) described below, and a generator 42 driven by the engine 41 to generate electricity.

[0028] Each motor 24 is electrically connected to the generator 42 via an electric speed controller 36 (including an inverter (not shown)) and a power control unit 35. With this connection, the electric power generated by the generator 42 is supplied to the motor 24 via the power control unit 35 and the electric speed controller 36.

[0029] The battery 31 is composed of a secondary battery capable of charging and discharging electric power. The battery 31 is electrically connected to the generator 42 via the power control unit 35, and is configured to charge the electric power generated by the generator 42. The battery 31 is electrically connected to each motor 24 via the power control unit 35 and the electric speed controller 36, and is configured to supply electric power discharged from the battery 31 to each motor 24. The battery 31 is provided with sensors (not shown) that detect the current and voltage of the battery 31, and a battery temperature sensor 74 that detects the temperature of the battery 31, and these sensors are configured to send electric signals related to the detection results to the main controller 33. The battery temperature sensor 74 corresponds to an example of a battery temperature detection means in this disclosed technology.

[0030] Fuel (e.g., gasoline) is stored in the fuel tank 32. This fuel is used to drive the engine 41. A level sensor (not shown) provided in the fuel tank 32 is configured to send an electrical signal related to the remaining amount of fuel to the main controller 33.

[0031] The main controller 33 is configured as a small computer and controls all operations related to the multicopter 1. The main controller 33 includes a wind direction acquisition unit 45, a rotation control unit 46, a wind power acquisition unit 47, a machine control unit 48, and an engine control unit 50. Here, for example, the engine control unit 50 controls the operation of the engine 41 in order to control power generation in the generator 42. The main controller 33 controls the operation of the engine 41, the supply of power from the generator 42 to each motor 24, charging from the generator 42 to the battery 31, and discharging from the battery 31 to each motor 24. The main controller 33 corresponds to an example of a control means in the disclosed technology.

[0032] The flight controller 34 is a device that controls the flight of the multicopter 1. The flight controller 34 sends electrical signals to the main controller 33 and the electric speed controller 36 to instruct thrust related to the flight of the multicopter 1, while receiving electrical signals related to the charging state of the battery 31 from the main controller 33. The flight controller 34 receives electrical signals related to the pilot's operation commands from the remote control 30, which will be described later, and electrical signals related to detection results from various sensors 28, which will be described later.

[0033] The power control unit 35 is a device that controls the power supplied to each motor 24. The power control unit 35 receives power generated by the generator 42, supplies and receives power to and from the battery 31, and supplies power to the electric speed controller 36. The power control unit 35 receives an electric signal related to a charge / discharge switching command from the main controller 33. The power control unit 35 also sends an electric signal related to the current of the battery 31 and an electric signal related to the current of the generator 42 to the main controller 33.

[0034] The electric speed controller 36 is a device that controls the rotation speed of each motor 24. The electric speed controller 36 supplies the electric power supplied via the power control unit 35 as drive power to each motor 24. The electric speed controller 36 receives an electric signal related to a thrust command from the flight controller 34.

[0035] The engine generator unit 12 includes a generator 42 and a part of the generator engine system 15 including an engine 41. The engine 41 is a drive source for the generator 42, and in this embodiment, is configured as a small reciprocating gasoline engine. That is, the engine 41 drives the generator 42 so that the generator 42 generates electric power to be supplied to each motor 24 or the battery 31. In addition, various components 57, 60, and 62 constituting the generator engine system 15 described later are configured to receive electric signals related to engine control commands for the purpose of generating electricity from an engine control unit 50 of the main controller 33.

[0036] In this embodiment, the multicopter 1 includes various sensors 28 and a remote control 30. The various sensors 28 include sensors for detecting the altitude, attitude, latitude, longitude, acceleration, and obstacles of the multicopter 1. The remote control 30 is a controller held by the pilot of the multicopter 1, and includes devices such as a transceiver that transmits electrical signals related to operations from a joystick operated by the pilot to the multicopter 1 and receives electrical signals related to operations from the multicopter 1.

[0037] In the multicopter 1 of this embodiment, each motor 24, the battery 31, and the engine 41 constitute a series hybrid system. That is, in this multicopter 1, the engine 41 is used only for generating electricity by the generator 42, each motor 24 is used to rotate and drive each rotor 25, and the battery 31 is used to charge and discharge the electricity generated by the generator 42. In this way, the multicopter 1 is configured to fly by operating the generator 42 with the power of the engine 41 to generate electricity, and operating each motor 24 with the generated electricity to rotate each rotor 25. In addition, in this multicopter 1, the surplus electricity that is supplied to each motor 24 out of the electricity generated by the generator 42 with the power of the engine 41 is temporarily stored in the battery 31, and is supplied from the battery 31 to each motor 24 as needed.

[0038] The multicopter 1 configured as described above realizes various flight modes by supplying power to each motor 24 and rotating each of the rotors 25. That is, the multicopter 1 realizes hovering flight by balancing the lift generated by each rotor 25 with the gravity acting on the multicopter 1 by controlling the rotation speed of each rotor 25. The multicopter 1 realizes ascending flight by making the lift generated by each rotor 25 larger than the gravity acting on the multicopter 1, and realizes descending flight by making the lift generated by each rotor 25 smaller than the gravity acting on the multicopter 1. In addition, the multicopter 1 realizes forward, backward, and left / right movement flight by controlling the rotation speed of each rotor 25 and creating an imbalance in the lift generated by each rotor 25. Furthermore, the multicopter 1 realizes turning (rotational) flight by providing a difference in the rotation speed of each rotor 25 that rotates relative to each other.

[0039] Here, the main controller 33 sends an electrical signal regarding a power supply switching command to the power control unit 35, thereby controlling the supply of power generated by the generator 42 to each motor 24 and the charging of the battery 31, and also controlling the discharging of the power charged in the battery 31 to each motor 24.

[0040] [About the generator engine system] Next, the generator engine system 15 will be described. Fig. 3 is a schematic diagram showing the generator engine system 15 of this embodiment and some of its associated devices. The configuration of the generator engine system 15 will be described in detail below with reference to Fig. 3.

[0041] This power generation engine system (hereinafter simply referred to as the "engine system") 15 includes an engine 41 consisting of a single cylinder. The engine 41 is a four-stroke reciprocating engine, and includes one cylinder 52 including a combustion chamber, a crankshaft 53, and other well-known components. The engine 41 is provided with an intake passage 54 through which intake air flows to the engine 41 to introduce the intake air into the cylinder 52, and an exhaust passage 55 for leading out exhaust air from the cylinder 52. An air cleaner 56 is provided at the entrance of the intake passage 54. A surge tank 54a is provided midway through the intake passage 54, and a throttle device 57 is provided upstream of the surge tank 54a. The throttle device 57 opens and closes to adjust the amount of intake air flowing through the intake passage 54. The throttle device 57 is formed of a poppet valve, and includes a valve body (not shown) that reciprocates relative to a valve seat, and a step motor 58 that drives the valve body to vary its opening. The engine system 15 of this embodiment is not provided with a throttle sensor for detecting the opening degree of the valve body (throttle opening degree). The throttle device 57 adjusts the amount of intake air flowing through the intake passage 54 by opening and closing the flow passage with the valve body. Meanwhile, a catalyst 59 for purifying exhaust gas is provided in the exhaust passage 55.

[0042] The intake passage 54 is provided with one injector 60 for injecting fuel into the passage 54. The injector 60 is configured to inject fuel (gasoline) supplied from the above-mentioned fuel tank 32. The engine 41 of this embodiment operates with an engine cycle including a series of intake strokes, compression strokes, explosion strokes, and exhaust strokes. In the intake passage 54, a combustible mixture is formed by the intake air introduced during the intake stroke of the engine cycle and the fuel injected into the intake passage 54 from the injector 60.

[0043] The engine 41 is provided with one spark plug 61 and one ignition coil 62 corresponding to each cylinder 52. The spark plug 61 sparks upon receiving an ignition signal output from the ignition coil 62. In the cylinder 52, the mixture explodes and burns due to the spark action of the spark plug 61 during the compression stroke of the engine cycle, and the explosion stroke progresses. The exhaust gas after combustion is discharged from the cylinder 52 to the exhaust passage 55 during the exhaust stroke. The exhaust gas flows through a catalyst 59, where it is purified, and is discharged to the outside. By periodically repeating this series of engine cycles with a crank angle of 720°C A, the crankshaft 53 of the engine 41 rotates, and the engine 41 obtains an output. In this embodiment, the crankshaft 53 of the engine 41 is directly connected to the drive shaft of the generator 42. Therefore, the rotation speed of the drive shaft of the generator 42 is the same as the rotation speed of the crankshaft 53.

[0044] Various sensors 71, 72, 73 provided corresponding to the engine 41 constitute means for detecting the operating state of the engine 41. The engine temperature sensor 71 provided in the engine 41 detects the temperature of the cylinder block of the engine 41 as the engine temperature THE, and outputs an electric signal corresponding to the detected value. The rotation speed sensor 72 provided in the engine 41 detects the rotation speed of the crankshaft 53 as the engine rotation speed NE, and outputs an electric signal corresponding to the detected value. The intake pressure sensor 73 provided in the surge tank 54a detects the intake pressure PM in the surge tank 54a (intake passage 54), and outputs an electric signal corresponding to the detected value.

[0045] The engine system 15 includes the above-mentioned engine control unit 50 for controlling the operation of the engine 41. The various sensors 71 to 73 are connected to the engine control unit 50. The step motor 58 of the throttle device 57, the injectors 60, and the ignition coil 62 are also connected to the engine control unit 50. As is well known, the engine control unit 50 includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like.

[0046] In this embodiment, the engine control unit 50 controls a throttle device 57 (step motor 58), each injector 60, and an ignition coil 62 based on electric signals from various sensors 71 to 73 in order to operate the engine 41.

[0047] FIG. 4 shows a graph of the relationship between the engine speed and the generator 42 current (power generation current) during flight of the multicopter 1 and the iso-fuel consumption rate line EFCL, iso-power line EOL, engine full-throttle performance line WOT, iso-voltage line IL, and operating line OL. In FIG. 4, the iso-fuel consumption rate line EFCL is shown by a dashed line, the iso-power line EOL is shown by a solid line, the engine full-throttle performance line WOT is shown by a thick two-dot dashed line, the iso-voltage line IL is shown by a dashed line, and the operating line OL is shown by a thick solid line. The operating line OL is set so as to be perpendicular to the iso-fuel consumption rate line EFCL. The multiple iso-voltage lines IL have a higher voltage from the left side A1 to the right side A2 of the arrangement. The multiple iso-power lines EOL have a higher output from the lower side B1 to the upper side B2 of the arrangement. The multiple iso-fuel consumption rate lines EFCL have a higher fuel consumption rate from the middle side C1 to the outer side C2 of the arrangement. In this embodiment, the output of the engine 41 is set to transition on the operating line OL so that the flight output of the multicopter 1 and the power generation output of the generator 42 are the same. In the multicopter 1, the generator 42 is usually operated at a fuel consumption operating point P1 on the operating line OL where the fuel consumption of the engine 41 is optimal, and when the state of charge (SOC) drops or extremely large flight power is required, the generator 42 is operated at an output operating point P2 on the operating line OL, and when overheating of the battery 31 is to be avoided, the generator 42 is operated at an intermediate operating point P3 on the operating line OL between the fuel consumption operating point P1 and the output operating point P2. Regardless of this, the output of the generator 42 is changed according to the flight power.

[0048] In the multicopter 1 of this embodiment, the cause of overheating of the battery 31 configured to be chargeable and dischargeable is mainly the influence of Joule heat due to internal resistance. In order to avoid overheating of the battery 31, it is preferable to reduce the current due to charging and discharging of the battery 31 to as close to zero as possible. The power required for flying the multicopter 1 varies depending on the motion state and attitude of the aircraft 11, and disturbances such as wind. By changing the output of the generator 42 in accordance with the flight power required for this flight, the current related to charging and discharging of the battery 31 can be reduced to as close to zero as possible, making it possible to suppress overheating of the battery 31. Therefore, the main controller 33 is configured to execute the following power supply control in order to suppress overheating of the battery 31.

[0049] Here, the main controller 33 is configured to supply generated power PG (see Figures 6 to 8) from the generator 42 to each motor 24 in order to satisfy the flight power FP (see Figures 6 to 8) required for the flight of the multicopter 1, and to discharge battery power BP (see Figures 6 to 8) from the battery 31 to each motor 24 to make up for the power that is insufficient with the generated power PG alone.

[0050] [About power supply control] Next, a description will be given of the power supply control executed by the main controller 33. The contents of this power supply control are shown in a flowchart in FIG.

[0051] When the process proceeds to this routine, the main controller 33 acquires the temperature (battery temperature) THB of the battery 31 based on the detection value of the battery temperature sensor 74 in step 100 .

[0052] Next, in step 110, the main controller 33 judges whether the acquired battery temperature THB is equal to or higher than a predetermined judgment temperature TH1. This judgment temperature TH1 is, for example, "60° C." If the judgment result is positive, the main controller 33 judges that there is a risk of overheating in the battery 31, and moves the process to step 120. If the judgment result is negative, the main controller 33 judges that there is no risk of overheating in the battery 31, and returns the process to step 100.

[0053] In step 120, the main controller 33 controls the power control unit 35 to increase the load current JLC ​​of the generator 42 by, for example, "5 A."

[0054] Next, in step 130, the main controller 33 increases the power generation load of the generator 42 in order to increase the generated power PG supplied from the generator 42 to each motor 24. To this end, the main controller 33 controls the throttle device 57 (increases the throttle opening) to increase the rotation speed of the engine 41 and thereby increase the rotation speed of the generator 42, for example, by "200 rpm."

[0055] Next, in step 140, the main controller 33 reduces the discharge load of the battery 31 in order to reduce the battery power BP discharged from the battery 31 to each motor 24. To this end, the main controller 33 controls the power control unit 35 to reduce the battery current BC discharged from the battery 31.

[0056] Next, in step 150, the main controller 33 judges whether the battery current BC is within a predetermined range value RV1. This range value RV1 is, for example, "-10A to +10A." Here, the main controller 33 smoothes the battery current BC to suppress variations in the battery current BC. If the result of this judgment is positive, the main controller 33 shifts the process to step 160, and if the result of this judgment is negative, the main controller 33 returns the process to step 120.

[0057] Here, when the process returns from step 150 to step 120, the main controller 33 repeats the processes of steps 120 to 150. When increasing the load current JLC ​​and the rotation speed (power generation load) of the generator 42, the main controller 33 increases them stepwise at predetermined time intervals (e.g., 1 second). When reducing the battery current BC (discharge load) of the battery 31, the main controller 33 reduces it stepwise at predetermined time intervals (e.g., 1 second) in accordance with the stepwise increase in the load current JLC ​​and the rotation speed (power generation load).

[0058] In step 160 , the main controller 33 acquires the battery temperature THB based on the detection value of the battery temperature sensor 74 .

[0059] Next, in step 170, the main controller 33 judges whether the captured battery temperature THB is equal to or lower than a predetermined return temperature TH2. The return temperature TH2 is, for example, "55° C." If the result of this judgment is positive, the main controller 33 determines that there is no risk of overheating in the battery 31, and moves the process to step 180. If the result of this judgment is negative, the main controller 33 determines that there is still a risk of overheating in the battery 31, and returns the process to step 160.

[0060] In step 180, the main controller 33 returns the load current JLC ​​and the rotation speed (power generation load) of the generator 42 to the state before it was determined that there was a risk of overheating in the battery 31. To this end, the main controller 33 controls the power control unit 35 and the throttle device 57.

[0061] Furthermore, in step 190, the main controller 33 returns the battery current BC (discharge load) to the state before it was determined that there was a risk of overheating in the battery 31. To achieve this, the main controller 33 controls the power control unit 35. After that, the main controller 33 temporarily ends the process.

[0062] According to the above-described power supply control, when the battery temperature THB detected by the battery temperature sensor 74 becomes equal to or higher than a predetermined judgment temperature TH1, the main controller 33 judges that there is a risk of overheating of the battery 31, and increases the power generation load of the generator 42 in order to increase the generated power PG supplied from the generator 42 to each motor 24, and reduces the discharge load of the battery 31 in order to reduce the battery power BP discharged from the battery 31 to each motor 24.

[0063] According to the above-mentioned power supply control, when the main controller 33 reduces the discharge load of the battery 31, the main controller 33 reduces the battery current BC discharged from the battery 31 to each motor 24 so that it falls within a predetermined range value RV1.

[0064] According to the above-described power supply control, the main controller 33 increases the rotation speed of the engine 41 to increase the rotation speed of the generator 42 in order to increase the power generation load of the generator 42 .

[0065] According to the above-described power supply control, when the main controller 33 increases the power generation load of the generator 42, it increases the load stepwise at predetermined time intervals.

[0066] In addition, according to the power supply control described above, when reducing the discharge load of the battery 31, the main controller 33 reduces the discharge load in stages at predetermined time intervals in accordance with the gradual increase in the power generation load of the generator 42.

[0067] Furthermore, according to the power supply control described above, when the battery temperature THB detected by the battery temperature sensor 74 becomes equal to or higher than a predetermined judgment temperature TH1 and then drops to a predetermined return temperature TH2 or lower, the main controller 33 determines that there is no risk of overheating in the battery 31, and reduces the power generation load of the generator 42 to return the generated power PG supplied from the generator 42 to each motor 24 to the state before it was determined that there was a risk of overheating in the battery 31, and increases the discharge load of the battery 31 to return the battery power BP discharged from the battery 31 to each motor 24 to the state before it was determined that there was a risk of overheating in the battery 31.

[0068] [Actions and Effects of Multicopters] According to the configuration of the multicopter 1 of this embodiment described above, the multicopter 1 flies by supplying power to each motor 24 to rotate each rotor 25. Here, the main controller 33 (control means) controls the operation of the engine 41, the supply of power from the generator 42 to each motor 24, charging from the generator 42 to the battery 31, and discharging from the battery 31 to each motor 24. In order to satisfy the flight power FP required for the flight of the multicopter 1, the main controller 33 supplies the generated power PG from the generator 42 to each motor 24, and discharges the battery power BP from the battery 31 to each motor 24 to make up for the power shortage caused by the generated power PG alone. In addition, when the battery temperature THB detected by the battery temperature sensor 74 becomes equal to or higher than a predetermined judgment temperature TH1, the main controller 33 judges that the battery 31 is at risk of overheating, and increases the power generation load of the generator 42 to increase the power generation power PG supplied from the generator 42 to each motor 24, and reduces the discharge load of the battery 31 to reduce the battery power BP discharged from the battery 31 to each motor 24 (reducing the battery current BC). Therefore, when the temperature of the battery 31 becomes equal to or higher than the predetermined judgment temperature TH1 and is likely to overheat, the power generation power PG supplied from the generator 42 to each motor 24 increases, and instead the battery power BP borne by the battery 31 decreases, so that the current charged from the generator 42 to the battery 31 and the battery current BC discharged from the battery 31 to each motor 24 are suppressed. Therefore, in the multicopter 1 equipped with the generator 42 driven by the engine 41 and the chargeable and dischargeable battery 31 to supply power to each motor 24, overheating of the battery 31 can be suppressed, and power can be stably supplied from the battery 31 to each motor 24. As a result, it is possible to prevent the rotation of each motor 24 from becoming unstable due to overheating of the battery 31, thereby enabling safe flight and landing of the multicopter 1 to be achieved.

[0069] In addition, according to the configuration of this embodiment, the battery current BC discharged from the battery 31 to each motor 24 is reduced to fall within a predetermined range value RV1, so some fluctuation is allowed in the reduction of the battery current BC. Therefore, there is no sudden movement due to variations in the responsiveness of the generator 42 and the power controller unit 35 and the flight behavior of the multicopter 1, and a stable power supply operation can be realized.

[0070] Furthermore, according to the configuration of this embodiment, the power generation load of the generator 42 is increased stepwise at predetermined time intervals, which prevents abrupt changes in the operation of the generator 42. This allows the battery 31 and the power controller unit 35 to operate stably.

[0071] Furthermore, according to the configuration of this embodiment, the discharge load of the battery 31 is gradually reduced at predetermined time intervals in accordance with the gradual increase in the power generation load of the generator 42, thereby suppressing a sudden change in the discharge load of the battery 31. Therefore, the battery 31 and the power controller unit 35 can be operated stably.

[0072] Furthermore, according to the configuration of this embodiment, when the battery temperature THB becomes equal to or higher than a predetermined judgment temperature TH1 and then falls to or below a predetermined return temperature TH2, and there is no longer a risk of overheating in the battery 31, the power generation load of the generator 42 is reduced in order to return the generated power PG supplied from the generator 42 to each motor 24 to the state before it was determined that there was a risk of overheating in the battery 31, and instead, the discharge load of the battery 31 is increased in order to return the battery power BP borne by the battery 31 to the state before it was determined that there was a risk of overheating in the battery 31. Therefore, the operating load of the engine 41 that drives the generator 42 is reduced to the original state. This makes it possible to suppress unnecessary deterioration in fuel efficiency of the engine 41.

[0073] FIG. 6 shows, in a time chart, the behavior of various parameters related to the power supply control when the multicopter 1 flies steadily according to this embodiment. FIG. 7 shows, in a time chart, the behavior of various parameters related to the power supply control when the multicopter 1 increases its cruising speed or its altitude during steady flight according to this embodiment. FIG. 8 also shows, in a time chart, the behavior of various parameters related to the power supply control when the multicopter 1 encounters a headwind during steady flight according to this embodiment. In FIG. 6 to FIG. 8, (a) shows the change in the battery temperature THB, (b) shows the state of the flight power FP required for the flight of the multicopter 1, (c) shows the change in the generated power PG of the generator 42, (d) shows the change in the engine speed NE (which is also the speed of the generator 42), (e) shows the change in the load current JLC ​​of the generator 42, (f) shows the change in the battery power BP, and (g) shows the change in the battery current BC discharged from the battery 31. However, in FIG. 7 and FIG. 8, the change in battery temperature THB in (a) is omitted.

[0074] As shown in FIG. 6, when the multicopter 1 flies steadily, at time t1, when the battery temperature THB (a) becomes equal to or higher than a predetermined judgment temperature TH1 (for example, 60° C.), the engine speed NE (d) increases (for example, 200 rpm), the generated power PG (c) increases accordingly (for example, 250 W), and the load current JLC ​​(e) increases (for example, 5 A). At this time, in accordance with the increase in the load current JLC, the battery power BP (f) decreases (for example, 250 W), and the battery current BC (gf) decreases (for example, 5 A). After that, even at time t2 when a predetermined time (for example, 1 second) has elapsed, the engine speed NE (d) further increases (for example, 200 rpm), the generated power PG (c) further increases (for example, 250 W), and the load current JLC ​​(e) further increases (for example, 5 A). At this time, in accordance with the increase in the load current JLC, the battery power BP of (f) further decreases (e.g., 250 W), the battery current BC of (gf) further decreases (e.g., 5 A), and the battery current BC falls within a predetermined range value RV1 (e.g., +10 A to -10 A). Thus, according to the power supply control of this embodiment, the operating point of the generator 42 is changed until the battery current BC falls within the predetermined range value RV1, the engine speed NE of (d), the generated power PG of (c), and the load current JLC ​​of (e) increase stepwise at predetermined times (e.g., 1 second), and in accordance with the increase in the load current JLC, the battery power BP of (f) and the battery current BC of (g) decrease stepwise at predetermined times (e.g., 1 second). Here, at time t2, the battery current BC (g) falls within a predetermined range value RV1, so there is no change in the generated power PG (c), the engine speed NE (d), the load current JLC ​​(e), the battery power BP (f), and the battery current BC (g), and at time t3, the battery temperature THB starts to decrease. Then, at time t4, when the battery temperature THB falls below a predetermined return temperature (e.g., 55°C), the generated power PG (c), the engine speed NE (d), and the load current JLC ​​(e) each decrease to their original states before they increased, and the battery power BP (f) and the battery current BC (g) increase to their original states before they decreased.In this way, when the multicopter 1 is in steady flight, the flight power FP (b) is satisfied by the generated power PG (c) and the battery power BP (f) and is always a constant value. According to the power supply control of this embodiment, when the battery temperature THB becomes equal to or higher than a predetermined judgment temperature TH1, the burden ratio of the generated power PG is increased and the burden ratio of the battery power BP is reduced instead, so that an increase in the battery temperature THB can be avoided.

[0075] On the other hand, as shown in FIG. 7, when the multicopter 1 increases the cruising speed or increases the altitude during steady flight, or as shown in FIG. 8, when the multicopter 1 receives a headwind during steady flight, during steady flight from time t0 to time t3, the various parameters (b) to (g) behave similarly to those in FIG. 6. Then, at time t4, when the multicopter 1 increases the cruising speed or receives a headwind and the flight power FP increases, immediately thereafter, the battery power BP (f) increases once, and the battery current BC (g) increases. Then, when the battery current BC (g) exceeds a predetermined range value RV1, at time t5, the engine speed NE (d) increases (e.g., 200 rpm) to increase the output of the generator 42, and accordingly the generated power PG (c) increases (e.g., 250 W), and the load current JLC ​​(e) increases (e.g., 5 A). Then, between time t5 and time t7, (c) generated power PG, (d) engine speed NE, and (e) load current JLC ​​increase stepwise at predetermined time intervals (e.g., 1 second), and in accordance with these increases, (f) battery power BP and (g) battery current BC decrease stepwise at predetermined time intervals (e.g., 1 second). In this way, even when flight power FP increases, the burden of generated power PG is increased, but the burden of battery power BP is reduced instead, so that an increase in battery temperature THB can be avoided.

[0076] Furthermore, according to the configuration of the multicopter 1 of this embodiment, the engine 41 of the power generating engine system 15 drives the generator 42 to generate electricity, and the generated electricity is supplied to each motor 24 to fly the multicopter 1. The generated electricity is also charged to the battery 31 to replenish the charge. Therefore, even if the engine 41 stops and the generator 42 cannot be driven, the power charged in the battery 31 can be supplied to each motor 24, enabling the multicopter 1 to fly. Therefore, the cruising distance and flight time of the multicopter 1 can be extended by the amount that the battery 31 can be charged and replenished with the power generated by the generator 42.

[0077] [Another embodiment] It should be noted that the disclosed technology is not limited to the above-described embodiment, and parts of the configuration can be appropriately modified and implemented without departing from the spirit of the disclosed technology.

[0078] (1) In the above embodiment, the opening of the throttle device 57 is controlled to change the rotation speed of the engine 41. However, instead of the throttle device 57, the amount of fuel injected from the injector 60 may be controlled, or the ignition of the air-fuel mixture by the spark plug 61 may be controlled.

[0079] (2) In the above embodiment, the appearance of the multicopter 1 shown in FIG. 1 is merely an example, and the shape of the airframe 11, the number and arrangement of the motors 24 and rotors 25, etc. can be changed as appropriate. [Industrial Applicability]

[0080] The disclosed technology can be applied to a multicopter equipped with an engine-driven generator and a rechargeable battery. [Explanation of symbols]

[0081] 1 Multicopter 24 Motor 25 Rotor 31 Battery 33 Main controller (control means) 41 Engine 42 Generator 74 Battery temperature sensor (battery temperature detection means) THB Battery Temperature FP flight power PG Power Generation BP Battery Power JLC Generator Load Current BC Battery Current RV1 Range Value TH1 judgment temperature

Claims

1. A plurality of rotors; a motor for driving and rotating each of the rotors; a battery configured to be capable of charging and discharging power supplied to the motor; a generator for generating power supplied to the motor and power charged to the battery; an engine for driving the generator; A multicopter includes a control unit for controlling operation of the engine, supply of electric power from the generator to the motor, charging of the battery from the generator, and discharging of the battery to the motor, and the multicopter flies by supplying electric power to the motor to rotate each rotor, a battery temperature detection means for detecting a temperature of the battery; The control means is configured to supply generated power from the generator to the motor in order to satisfy the flight power required for flying the multicopter, and to discharge battery power from the battery to the motor in order to compensate for power that is insufficient with only the generated power, the control means, when the temperature of the battery detected by the battery temperature detection means becomes equal to or higher than a predetermined judgment temperature, increases a power generation load of the generator in order to increase the generated power supplied from the generator to the motor, and reduces a discharge load of the battery in order to reduce the battery power discharged from the battery to the motor; When the temperature of the battery detected by the battery temperature detection means becomes equal to or higher than the judgment temperature and then falls to or below a predetermined return temperature, the control means reduces the power generation load of the generator in order to return the generated power supplied from the generator to the motor to the state before the increase, and increases the discharge load of the battery in order to return the battery power discharged from the battery to the motor to the state before the reduction. A multicopter characterized by

2. The multicopter according to claim 1, When the control means reduces the discharge load of the battery, the control means reduces the battery current discharged from the battery to the motor so that the battery current falls within a predetermined range. A multicopter characterized by

3. The multicopter according to claim 1 or 2, The control means increases the rotation speed of the engine to increase the power generation load of the generator. A multicopter characterized by

4. The multicopter according to any one of claims 1 to 3, When increasing the power generation load of the generator, the control means increases the power generation load stepwise at predetermined time intervals. A multicopter characterized by

5. The multicopter according to claim 4, When the control means reduces the discharge load of the battery, the control means reduces the discharge load stepwise at predetermined time intervals in accordance with a stepwise increase in the power generation load. A multicopter characterized by

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