JP2020040550A - Wired power supply type unmanned flight vehicle - Google Patents

Abstract

To provide an unmanned flight vehicle capable of flying for a long time.SOLUTION: A wired power supply type unmanned flight vehicle 10 includes a ground power supply unit that supplies power to an unmanned flight vehicle, an unmanned flight vehicle power unit that supplies power to motors and electronic devices of the unmanned flight vehicle, and a feeder line 14 connecting the ground power supply unit and the unmanned flight vehicle power unit. In the wired power supply type unmanned flight vehicle, supply power supplied from the ground power supply unit to the unmanned flight vehicle power supply unit via the feeder line has a periodic voltage or current waveform. The periodic waveform is an AC waveform or a switching waveform. The AC waveform at a low frequency is a sine wave from a commercial power supply, and the AC waveform at a high frequency is a switching waveform. A circuit configuration of a transformer or a converter can be used for a feeder circuit that performs wired power supply, and a sine wave or a switching waveform is transmitted through the feeder line.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for supplying power to an unmanned aerial vehicle that flies by remote control, such as a small unmanned helicopter or an unmanned aerial vehicle.

  An unmanned aerial vehicle generally called a drone has a plurality of rotary wings, and is capable of three-dimensional movement and stable stopping (hovering) in the air by maneuvering on the ground. For this reason, it is widely used from shooting in the air to transporting objects.

  Unmanned aerial vehicles are powered by a motor mounted on the unmanned aerial vehicle, and power is supplied to the motors, the electronic devices, and the electronic circuits that rotate the rotors. It is an ion battery. The lithium-ion battery is characterized by a high output of 3.7 V per cell while being small and lightweight.

  There is also a system in which a power source is placed on the ground and power is supplied to an unmanned aerial vehicle by wire, and disclosed, for example, in Patent Documents 1 to 4. Although the power supply from the ground is direct current, the motor consumes large power and needs to supply 500 to 1000 W per motor. In many cases, a brushless motor is used as the motor for the rotor blade, and a DC voltage of 12 to 24 V is required. If the power supplied from the ground is set to the same voltage as the DC voltage of the motor, a current of 50 A or more is required, and the power supply line becomes thick and heavy. Since the unmanned aerial vehicle flies over 100 to 150 m, the power supply line needs to be 3 mm or more in thickness, and the weight exceeds 10 kg.

  In order to make the power supply line thinner and lighter, a method of increasing the DC voltage supplied from the ground has been proposed. For example, Patent Document 1 supplies a DC voltage of 200 V or more, for example, 360 V, and Patent Document 2 supplies a DC voltage of 160 V.

  Patent Literature 4 describes that an AC / DC converter is required for the unmanned aerial vehicle when the power transmitted from the ground to the unmanned aerial vehicle is an alternating current, but does not describe any efficiency.

Patent Document 1: JP-A-2006-74257
Patent Document 2: WO2014 / 203593
Patent Document 3: WO2014 / 152159
Patent Document 4: JP-A-2017-013653

  The unmanned aerial vehicle is required to fly for a long time. However, in a conventional system in which a battery is mounted on an unmanned aerial vehicle, the flight time is about 15 to 25 minutes due to a capacity problem. In order to perform a long flight, there is a problem that the capacity of the battery must be increased and the weight of the unmanned aerial vehicle increases.

  In a system in which electric power is supplied to an unmanned aerial vehicle via a wire, electric power is transmitted using a DC voltage, and thus there is a problem that a loss in a transmission line is large. For this reason, efficient power supply is required.

  An object of the present invention is to provide an unmanned aerial vehicle that can fly for a long time.

  (1) A wire-powered unmanned aerial vehicle according to the present invention includes: a ground power supply unit that supplies power to the unmanned aerial vehicle; an unmanned aerial vehicle power unit that supplies power to a motor and an electronic device of the unmanned aerial vehicle; A power supply line connecting the ground power supply unit and the unmanned aerial vehicle power supply unit, and the power supplied from the ground power supply unit to the unmanned aerial vehicle power supply unit via the power supply line is a periodic voltage or It has a current waveform.

  (2) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the supply power is a single-phase AC power.

  (3) In the wire-powered unmanned aerial vehicle according to the present invention, it is preferable that the power supply line is a single-phase three-wire type.

  (4) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the supplied power is three-phase AC power.

  (5) In the wired powered unmanned aerial vehicle according to the present invention, the single-phase AC power or the three-phase AC power is preferably AC power from a commercial power supply.

  (6) In the wired powered unmanned aerial vehicle according to the present invention, preferably, the three-phase AC power is converted from the single-phase AC power.

  (7) In the wire-powered unmanned aerial vehicle according to the present invention, a booster is provided in the ground power supply unit, and AC power from the commercial power supply is boosted by the booster, and the unmanned unmanned aerial vehicle is supplied via a power supply line. Preferably, power is supplied to the flying object power supply.

  (8) In the wire-powered unmanned aerial vehicle according to the present invention, the ground power unit is provided with a DC / AC inverter or an AC / AC converter, and the unmanned aerial vehicle power unit is provided with an AC / DC converter and a DC. / DC and DC / AC inverters are preferably provided.

  (9) In the wire-powered unmanned aerial vehicle according to the present invention, it is preferable that the output waveform of the supplied power is a switching waveform.

  (10) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that a cutoff frequency of the power supply line is higher than a switching frequency of the switching waveform.

  (11) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the power supply line has a function of removing noise from the switching waveform.

  (12) In the wire-powered unmanned aerial vehicle according to the present invention, it is preferable that the wavelength corresponding to the switching frequency is １ ／ of the length of the power supply line.

  (13) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the switching waveform is an output waveform of a chopper circuit.

  (14) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the switching waveform is a transformer output waveform of an insulating converter.

  (15) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the switching element of the chopper circuit or the insulating converter is an element made of a GaN transistor or a SiC transistor.

  (16) In the wire-powered unmanned aerial vehicle according to the present invention, it is preferable that the unmanned aerial vehicle power supply unit is provided with a smoothing circuit.

  (17) In the wire-powered unmanned aerial vehicle according to the present invention, it is preferable that the ground power supply unit includes a vehicle-mounted battery.

  (18) In the wired powered unmanned aerial vehicle according to the present invention, it is preferable that the ground power supply unit includes an engine generator.

  (1) A wired power supply type unmanned aerial vehicle according to the present invention includes a ground power supply unit that supplies power to the unmanned aerial vehicle, an unmanned aerial vehicle power supply unit that supplies power to a motor and an electronic device of the unmanned aerial vehicle, and a ground power supply unit. And a power supply line connecting the unmanned aerial vehicle power supply unit. The power supplied from the ground power supply unit to the unmanned aerial vehicle power supply unit via the power supply line has a periodic voltage or current waveform. For this reason, the AC waveform at a low frequency can be supplied with a small loss by using a high voltage. In addition, when power is supplied at a high frequency, noise is removed by a power supply line, so that it is not necessary to provide a snubber circuit that is generally used, and the number of components can be reduced. Further, the cycle of the voltage or current waveform can be set widely.

  (2) According to the wire-powered unmanned aerial vehicle of the present invention, since the supply power is single-phase AC power, the AC power supply can be easily stepped up by a transformer.

  (3) According to the wire-powered unmanned aerial vehicle of the present invention, since the power supply line is a single-phase three-wire system, power can be transmitted at twice the voltage of the single-phase two-wire system.

  (4) According to the wire-powered unmanned aerial vehicle of the present invention, since the supplied power is three-phase AC power, loss on the power supply line is smaller than that of single-phase AC power.

  (5) According to the wire-powered unmanned aerial vehicle of the present invention, since the single-phase AC power or the three-phase AC power is the AC power from the commercial power supply, the power supply can be easily used.

  (6) According to the wire-powered unmanned aerial vehicle of the present invention, since the three-phase AC power is converted from the single-phase AC power, the single-phase AC power is widely used and therefore easy to use.

  (7) According to the wire-powered unmanned aerial vehicle of the present invention, the booster is provided in the ground power supply unit, and the AC power from the commercial power is boosted by the booster, and the power supply of the unmanned aerial vehicle is supplied via the power supply line. Since the power is supplied to the unit, the loss in the power supply line can be suppressed.

  (8) In the wire-powered unmanned aerial vehicle of the present invention, the ground power supply unit is provided with a DC / AC inverter or an AC / AC converter, and the unmanned aerial vehicle power supply unit is provided with an AC / DC converter and a DC / DC. And a DC / AC inverter. The AC power is not limited to a commercial power supply, but can be converted to an arbitrary voltage and frequency by a DC / AC inverter or an AC / AC converter, and efficient power supply is possible. In addition, the unmanned aerial vehicle power supply unit is provided with an AC / DC converter, DC / DC and DC / AC inverter, and is used to control devices mounted on the unmanned aerial vehicle, sensors, motors, cameras, and other mounted devices. The most suitable power supply can be supplied.

  (9) According to the wire-powered unmanned aerial vehicle of the present invention, since the supply power is a switching waveform, the switching waveform in the AC / DC converter or the DC / DC converter is supplied from the power supply line, so that the power supply line is provided. Can be used as one component of the converter.

  (10) According to the wire-powered unmanned aerial vehicle of the present invention, since the cutoff frequency of the power supply line is higher than the switching frequency of the switching waveform, the amount of attenuation of the switching waveform can be reduced.

  (11) According to the wire-powered unmanned aerial vehicle of the present invention, since the power supply line has the function of removing noise of a switching waveform, noise generated by switching using the frequency characteristics of the power supply line. Is attenuated.

  (12) In the wire-powered unmanned aerial vehicle of the present invention, the wavelength corresponding to the switching frequency is ４ of the length of the power supply line. If the feeder line becomes longer, the wavelength associated with the switching frequency cannot be ignored, and must be matched with the characteristic impedance of the feeder line. Therefore, the wavelength of the switching frequency is set to １ ／ of the feeder line length. Let me. Thus, the power supply line can have a function as a transformer.

  (13) According to the wire-powered unmanned aerial vehicle of the present invention, since the switching waveform is the output waveform of the chopper circuit, the power supply line can be used for removing noise of the switching waveform generated by the chipper circuit.

(14) According to the wire-powered unmanned aerial vehicle of the present invention, since the switching waveform is the transformer output waveform of the insulated converter, noise can be suppressed by using a transformer.
It is characterized by.

  (15) According to the wire-powered unmanned aerial vehicle of the present invention, since the switching element of the chopper circuit or the insulated converter is an element composed of a GaN transistor or a SiC transistor, switching at a high frequency becomes possible and the size is small. Thus, an efficient power supply circuit can be obtained.

  (16) According to the wire-powered unmanned aerial vehicle of the present invention, since the unmanned aerial vehicle power supply unit is provided with the smoothing circuit, the switching waveform is smoothed to achieve a desired operation for the unmanned aerial vehicle mounted device. Can be converted to power.

  (17) According to the wire-powered unmanned aerial vehicle of the present invention, since the ground power supply unit is equipped with an on-vehicle battery, even where commercial power is not available, an EV (Electric Vehicle), a hybrid vehicle, or the like is used. The unmanned aerial vehicle can be flown by the vehicle-mounted battery.

  (18) According to the wire-powered unmanned aerial vehicle of the present invention, since the ground power supply unit includes the engine generator, the unmanned aerial vehicle can be flown even in a place where commercial power is not available.

FIG. 1 is a conceptual diagram illustrating a wire-powered unmanned aerial vehicle according to an embodiment of the present invention. It is a block diagram explaining the power supply system of a wire feeding type unmanned aerial vehicle. FIG. 3 is a model diagram in a case where power is supplied from a single-phase AC power supply 40 to a power supply line 14 in a low frequency region. FIG. 4 is a model diagram in a case where power is supplied from a three-phase AC power supply to a power supply line in a low frequency region. It is a figure explaining the connection state of the load when three-phase alternating current power is supplied, and the relationship of a phase voltage and a phase current. FIG. 3 is a model diagram in a case where a power supply line 14 is a single-phase three-wire system. It is a figure showing an example of the frequency characteristic of copper wire resistance. It is a figure showing an example of the frequency characteristic of a CV cable. FIG. 4 is a model diagram when the power supply line 14 is viewed as a distributed constant line. It is a model diagram when connecting the load impedance Z _L to the reception terminal (z = 0) of the distributed constant line model. It is a figure which shows the case where a wavelength is (lambda) / 4 with respect to the length of a distributed constant line model. FIG. 2 is a block diagram of a power supply system relating to the unmanned aerial vehicle using an AC power supply of a commercial power supply. FIG. 2 is a diagram illustrating a configuration of a power supply circuit when commercial power is transmitted directly via a power supply line 14. FIG. 3 is a diagram showing a configuration of a power supply circuit in which a booster 44 is provided in a power supply unit 22 and a step-down unit 46 is provided in an unmanned aerial vehicle power supply unit 24 in order to reduce a loss in the power supply line 14. FIG. 4 is a diagram illustrating a configuration of a power supply circuit when AC power is transmitted in a single-phase three-wire system. FIG. 2 is a diagram illustrating a configuration of a power supply circuit for transmitting three-phase power via a power supply line. FIG. 2 is a block diagram of a power supply system related to the unmanned aerial vehicle when transmitting a switching waveform via a power supply line. FIG. 3 is a diagram illustrating a configuration of a power supply circuit that converts a DC power supply 62 into a three-phase AC power supply by a chopper circuit 60 and transmits the power to a power supply line 14. FIG. 2 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on a power supply line using a circuit configuration of a step-down DC / DC converter. FIG. 20 is a diagram illustrating an equivalent circuit in the circuit of the power supply unit 22 illustrated in FIG. 19B in consideration of a parasitic inductance and a parasitic capacitance. FIG. 2 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on a power supply line 14 using a circuit configuration of an asynchronous step-up DC / DC converter. FIG. 2 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on a power supply line using a circuit configuration of a flyback type DC / DC converter. FIG. 2 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on a power supply line by using a circuit configuration of a forward DC / DC converter. FIG. 3 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed by using a power supply line 14 instead of a transformer T, using a circuit configuration of a forward DC / DC converter.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the components in the present embodiment can be appropriately replaced with existing components and the like, and various variations can be made in combination with other existing components. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

  Unmanned aerial vehicles generally called drones have been used in various applications in recent years. However, a typical wireless drone uses a lithium-ion battery as a power source, and its continuous flight time is as short as about 20 minutes, making it unsuitable for applications requiring long flight times. For this reason, a system that enables a long flight by a wired power supply system has been adopted.

  The conventional wired power supply system supplies a DC (direct current) voltage via a power supply line. This is because most electronic devices mounted on unmanned aerial vehicles operate on DC voltage, and need to perform AC / DC conversion even when an alternating current (AC) voltage is supplied. However, when the DC voltage is supplied through the power supply line, the loss is large, and when the power supply line is long, a serious problem occurs.

  The supply of a DC voltage via a feed line in an unmanned aerial vehicle employs a method of feeding a high-voltage DC voltage of, for example, about 500 V to cover the loss, but the length of the feed line is limited, The range in which the unmanned aerial vehicle flies from the position of the power source is also limited.

  The unmanned aerial vehicle has a limited flight altitude, for example, 150 m or less in Japan. This is because the Civil Aeronautics Law stipulates that manned helicopters must fly at least 300 m in densely populated areas except for takeoff and landing, and at least 150 m in other places. This is because the area is a no-fly area. For this reason, if only the height of the flight is considered, a power supply line of 150 m may be used, but the flight is limited to the flight near the ground-based power supply base station.

  On the other hand, the transmission distance of the radio wave of the transmitter that wirelessly controls the unmanned aerial vehicle is 2000 to 3000 m, and the limit in the horizontal direction is not regulated. Therefore, theoretically, a power supply line of 2000 to 3000 m is necessary. It will be. For example, inundation due to a landslide caused by a landslide caused by a typhoon or heavy rain requires extensive investigation and monitoring over a long period of time, and a horizontal direction of about 2000 to 3000 m is rather a practically required distance. Is the length of the power feed line. For this reason, power supply with an AC voltage with little loss in the power supply line is indispensable.

  FIG. 1 is a conceptual diagram illustrating a wired-powered unmanned aerial vehicle according to an embodiment of the present invention. The unmanned aerial vehicle 10 and the ground-based base station 12 are connected by a power supply line 14, and the power supply line 14 is provided with a winding section 16 for preventing slack. A ground power supply for supplying power to the unmanned aerial vehicle 10, an unmanned aerial vehicle power supply for supplying a power to a motor and an electronic device of the unmanned aerial vehicle 10, and a power supply line connecting the ground power supply and the unmanned aerial vehicle power supply The power supplied from the ground power supply unit to the unmanned aerial vehicle power supply unit via the power supply line 14 has a periodic voltage or current waveform. The ground power supply unit is provided in the base station 12, and the unmanned aerial vehicle power supply unit is provided in the unmanned aerial vehicle 10.

  Although the base station 12 exemplarily shows a car in FIG. 1, the base station 12 may be outdoors or indoors as long as there is a space having a ground power supply unit. When a car is used as the base station 12, a vehicle-mounted battery is used. Further, the ground power supply unit may include an engine generator. Since the AC power is generated by the rotation of the engine, the unmanned aerial vehicle 10 can fly even in a place where commercial power is not available.

  The periodic voltage or current waveform transmitted to the unmanned aerial vehicle power supply unit via the power supply line 14 is a single-phase AC waveform, a three-phase AC waveform, or a switching waveform. The AC waveform is a sine wave, and the switching waveform is a rectangular wave in which a DC voltage is turned on / off by a switching element, or a triangular wave in some cases. Single-phase AC power is supplied by a single-phase AC waveform, and three-phase AC power is supplied by a three-phase AC waveform. Further, a voltage or a current turned on / off by the switching waveform is supplied.

  In the present invention, the transmission of the switching waveform on the power supply line 14 utilizes the basic circuit configuration of various DC / DC converters and AC / DC converters. The switching power supply forms a stabilized power supply by switching a DC voltage at a certain frequency. By using a basic circuit of the switching power supply, a power supply circuit for wired power supply to the unmanned aerial vehicle 10 is provided. It is characterized by: The switching waveform transmitted via the feed line 14 is smoothed by the unmanned aerial vehicle 10 and converted into a voltage required by the stabilized power supply.

  As the single-phase AC power or the three-phase AC power, AC power from a commercial power supply can be used. Three-phase AC power may be converted from single-phase AC power.

  FIG. 2 is a block diagram illustrating a power supply system for a wire-powered unmanned aerial vehicle. The unmanned aerial vehicle 10 includes a receiver 28, a flight control unit 26, an ESC (Electric Speed Controller) 36, a motor 34, a device control unit 30, an on-board device 32, a sensor 38, and an unmanned aerial vehicle power supply unit 24. The base station 12 includes a power supply unit 22 on a ground power supply unit 20, and supplies power to the unmanned aerial vehicle 10 via a power supply line 14. The power supply line 14 is configured to be windable by a winding unit 16, and the winding unit 16 adjusts the length of the power supply line 14 according to the distance between the base station 12 and the unmanned aerial vehicle 10. . The flight of the unmanned aerial vehicle 10 and the control of the on-board equipment 32 are performed by radio transmission of radio waves by the radio transmitter 18 from the ground. Further, the transmitter transmitter 18 may be connected to the unmanned aerial vehicle 10 together with the power supply line 14 by wire. These operations are performed by the pilot using the transmitter transmitter 18.

  The unmanned aerial vehicle 10 includes four quadcopters, six hexacopters, eight octocopters, and the like. The propeller (wing) is rotated by a motor 34. Hovering and forward / backward movement of the unmanned aerial vehicle 10 are performed by adjusting the rotation speed of the propeller. For example, when the rotational speed of the propeller in the forward direction is reduced, the propeller moves forward. Some models can adjust the angle of the propeller.

  When an ascent / descent or forward / backward operation is performed by a propo (proportional control system) 18, radio waves are transmitted to the unmanned aerial vehicle wirelessly and received by the receiver 28 in the unmanned aerial vehicle 10. The flight control unit 26 that has received the command from the receiver 28 performs arithmetic processing based on information from a sensor 38 that detects various information such as tilt, angle, and acceleration, and what kind of rotation each motor 34 causes. Decide. As the sensor 38, a gyro sensor is often used. The ESC 36 receiving the command from the flight control unit 26 rotates the motor 34 according to the command. The sensor 38 may include detection of GPS (Global Positioning System), atmospheric pressure, and the like.

  The unmanned aerial vehicle 10 is equipped with various devices depending on the purpose of the flight. For example, for aerial photography purposes, the mounted device 32 is a camera. It is a carrier for carrying luggage. The device control unit 30 controls the mounted device. When the mounted device 32 is a camera, a video signal captured by the camera is sent from the device control unit 30 to the transmitter 18 via the receiver 28. In this case, the receiver 28 and the transmitter 18 have a function capable of transmitting and receiving. Further, the transmitter 18 is provided with a storage unit for storing a video signal. Of course, the video signal may be stored by connecting to a personal computer or the like. For transmission and reception, 2.4 GHz band is used in Japan.

  As a motor of the unmanned aerial vehicle 10, a three-phase brushless DC motor (hereinafter, abbreviated as a brushless motor) is mainly used. The brushless motor has a built-in magnetic element for detecting the position of the rotor or an optical encoder. A signal is sent to the ESC 36 by this position detector. The motor winding is a three-phase Y-connection. Further, a permanent magnet is used for the rotor, and a Hall IC is used for the magnetic element for detection. A switching element is connected to the motor winding to constitute an inverter.

  The unmanned aerial vehicle power supply unit 24 supplies power to all electrically operated devices mounted on the unmanned aerial vehicle 10. If the motor 34 is a brushless motor, it supplies a three-phase AC voltage or a three-phase AC current whose phase is shifted by 120 degrees, and the flight control unit 26 and the device control unit 30 are configured by a CPU, a logic circuit, a ROM, and the like. , A voltage for the logic circuit is supplied. Further, the receiver 28, the on-board device 32, and the sensor 38 are also supplied with voltages and currents suitable for each.

  The ground power supply unit 20 includes a power supply unit 22 that supplies power to the unmanned aerial vehicle power supply unit 24 of the unmanned aerial vehicle 10 via the power supply line 14. The length of the power supply line 14 is adjusted by the winding unit 24 to prevent slack. In the unmanned aerial vehicle power supply unit 24, the supply power is once converted into a DC voltage, and further converted into a voltage suitable for each device of the unmanned aerial vehicle 10, and supplied.

  The present invention is characterized in that the power supplied from the power supply unit 22 has a periodic voltage or current waveform. The term “periodic” means a waveform having a constant frequency. In general, transmission of a waveform having a frequency requires consideration of a characteristic impedance depending on the length of the power supply line 14.

  The characteristic impedance changes depending on the frequency. In a low-frequency region that is sufficiently larger than the length of the feed line 14, the characteristic impedance is not affected by the wavelength, and the waveform reaches the unmanned aerial vehicle power supply unit 24 in the same phase. Can be considered as a lumped constant circuit. When the frequency increases, the frequency characteristics of the feeder line 14 must be taken into consideration even in a lumped circuit. Further, in a high frequency region where the frequency is higher, the effect of the standing wave cannot be ignored, and it is necessary to consider the reflected wave and to perform impedance matching.

  The length of the power supply line 14 may be 150 m, for example, if it covers only a height of 150 m. However, considering horizontal movement, a length of 2000 to 3000 m is required at the maximum.

If the frequency is f and the wavelength is λ, the speed of light is 3 × 10 ⁸ m / s, so that f = 3 × 10 ⁸ / λ. In consideration of the standing wave and impedance matching at λ / 4, when the length of the feed line 14 is 150 m, f = 3 × 10 ⁸ / (150 × 4) = 500 kHz. In the case where the length of the power supply line 14 is 3000 m, a similar calculation results in 25 kHz.

  Therefore, in the case of AC power transmission via the feed line 14, the frequency f and the length of the feed line 14 are in a very close relationship, the wavelength λ is sufficiently long with respect to the length of the feed line 14, and the lumped constant circuit , A medium-frequency region that can be considered in a lumped-constant circuit but in which the frequency characteristics of the feed line 14 must be considered, and a high-frequency region in which the presence of a standing wave must be considered. There must be. By supplying power in conformity with this frequency, efficient power supply can be performed. Hereinafter, the characteristics of the power supply line and the frequency in the low frequency region, the medium frequency region, and the high frequency region will be described.

The low-frequency region is a frequency region when the wavelength of the AC waveform is sufficiently long with respect to the length of the feed line 14. For example, when transmitting a commercial AC power supply, the frequency is 50 or 60 Hz, and when the frequency is 50 Hz, the wavelength λ is 6 × 10 ⁶ m. Even when the length of the feed line 14 is 3000 m, the wavelength λ is sufficiently long, and the feed line 14 can be considered as a lumped constant circuit.

FIG. 3 is a model diagram in a case where power is supplied from the single-phase AC power supply 40 to the power supply line 14 in a low frequency region. Single-phase AC power is supplied from the single-phase AC power supply 40 in the power supply unit 22 to the unmanned aerial vehicle power supply unit 24 via the power supply line 14. Let R be the feed line equivalent resistance of the feed line 14. Assuming that the voltage of the single-phase AC power supply 40 is V and the current flowing through the power supply line 14 is I, the loss power W _los is expressed by the following equation.
W _los = RI ² (1)
From equation (1), since the feeder line equivalent resistance R is constant, the smaller the current I, the smaller the power loss. If the same power W is supplied, W = VI, and the higher the voltage is, the smaller the current is. Therefore, the higher the voltage of the power supply line 14 is, the smaller the power loss is.

  FIG. 4 is a model diagram in a case where power is supplied from the three-phase AC power supply 42 to the power supply line 14 in a low frequency region. Three-phase AC power is supplied from the three-phase AC power supply 42 in the power supply unit 22 to the unmanned aerial vehicle power supply unit 24 via the power supply line 14. In the case of power supply by the three-phase AC power supply 42, the phase voltage and the phase current of the load change depending on the connection state of the load, that is, the Y connection or the Δ connection.

FIG. 5 is a diagram illustrating the relationship between the connection state of the load, the phase voltage, and the phase current when three-phase AC power is supplied. FIG. 5A is a diagram in the case where the load Z is Y-connected. In the Y connection, the phase current is the same as the current I flowing through the power supply line 14, but the phase voltage is 1/3 ^{1/2 of the} line voltage V. FIG. 5B is a diagram in the case where the load Z has a Δ connection. In the [Delta] connection, the phase voltage is the same as the line voltage V of the power supply line 14, but the current I flowing through the load Z is 1/3 ^1/2 . Therefore, in the case of three phases, the sum of the phase powers is the power supplied in three phases, and therefore, even if the load Z is Y-connected or the load Z is Δ-connected, the supplied power in three phases is 3 ^1/2 V · I, and ^31/2 times the power of the single-phase AC power can be obtained. Therefore, it is more advantageous to supply three-phase AC power to the power supply line 14 than to single-phase AC power.

FIG. 6 is a model diagram when the power supply line 14 is a single-phase three-wire system. The single-phase three-wire system is a system in which a neutral wire is grounded, and single-phase AC power is supplied to the upper and lower power supply lines 14 from the power supply unit 22 to the unmanned aerial vehicle power supply unit 24. In the case of the single-phase three-wire system, assuming that the power supply line equivalent resistance is R, the current flowing through the power supply line 14 is I, and the voltage at the load Z is V, the three-phase three-wire system is the single-phase three-wire system. Since current does not basically flow (cancels to zero) in the middle line among the lower lines, the loss power W _los lost in the power supply line 14 is equal to the load connected to the upper and lower lines. W _los = 2R · I ² . The power _{W Z} consumed by the load _becomes W Z = 2V · I. Since the current I is twice as large as that of the single-phase two-wire system shown in FIG. 3, if the power supplied to the load and the power loss in the power supply line are the same as the single-phase two-wire system, In the three-wire system, the feed line equivalent resistance R is １ ／.

  Since the feeder line equivalent resistance R of the feeder line 14 is inversely proportional to the cross-sectional area of the feeder line 14, the diameter of the single-phase three-wire feeder line 14 may be half that of the single-phase two-wire type. The weight can be reduced.

In the low frequency region, power supply may be performed in consideration of the power supply line equivalent resistance R of the power supply line 14, and a description has been given mainly of a commercial power supply having a frequency of 50 to 60 Hz.
(1) The higher the voltage is, the smaller the loss power W _{los in the} power supply line 14 is.
(2) The loss power W _los is smaller in three-phase AC power than in single-phase AC power.
(3) As for power supply of single-phase AC power, a single-phase three-wire system has less power loss W _los than a single-phase two-wire system, and the power supply line can be reduced in weight.

Next, power supply in the medium frequency region will be described. Medium frequency region, the switching frequency f _s of the power supply unit is directed to a frequency range to be considered a frequency characteristic of the feed line 14. The switching waveform is generated by turning on and off a DC voltage by a switching element. Thus, the switching waveform is used as the power supply.

  For example, assume that a CV cable is used as the power supply line 14. A CV cable is a cable in which a conductor is covered with a cross-linked polyethylene and the outer periphery is covered with a vinyl sheath. If a copper wire is used for the conductor, the resistance increases as the frequency increases due to a skin effect or the like.

  FIG. 7 is a diagram illustrating an example of a frequency characteristic of the copper wire resistance. In the illustrated example, when the frequency exceeds 10 kHz, the resistance increases due to the skin effect and the proximity effect of a plurality of strands. In addition, the equivalent capacitance between the lines is added, and as the frequency increases, the attenuation in the CV cable increases.

FIG. 8 is a diagram illustrating an example of the frequency characteristics of the CV cable. In the illustrated example, the attenuation increases when the frequency exceeds 10 kHz. In the medium frequency region, the power supply is designed using this frequency characteristic. When the cut-off frequency of 3dB attenuation and f _c, the cutoff frequency f _c is higher it is necessary than the switching frequency f _s. If the opposite view, a frequency lower than the cut-off frequency as the switching frequency range, the switching frequency f _s, it is necessary to design at a frequency included in the switching frequency range.

  In the frequency characteristic shown in FIG. 8, since the attenuation amount becomes 20 dB or more when the frequency exceeds 100 kHz, the rising and falling of the switching waveform becomes gentle. This is suitable for removing noise. A switching power supply forms a circuit by connecting electronic components and semiconductor components to be used with a wiring pattern. Noise is generated by a surge / ringing voltage generated when the switching element is turned off, a parasitic inductance of the wiring pattern and a switching element. Is generated as a resonance frequency due to the parasitic capacitance of. In a general switching power supply, the resonance frequency of the noise has a short wiring pattern and is several MHz or more. Therefore, the noise frequency exists in a frequency region where the attenuation is sufficiently large in the frequency characteristic, and the frequency characteristic of the power supply line 14 can be used as a noise removing function.

Power supply unit, by increasing the switching frequency f _s, since it reduced the capacitor of the capacitor to be used, the coil or transformer inductance can be miniaturized electronic components. However, by increasing the switching frequency f _s, the wavelength λ is shortened and the length of the feed line 14 can not be ignored. This frequency region is defined as a high frequency region. For example, a metal LAN cable is used for the power supply line 14 in the high frequency range.

  In the high-frequency region, the power supply line 14 cannot be handled by the lumped-constant circuit theory. Therefore, it is necessary to use the electromagnetic field theory or the distributed constant circuit theory. The electromagnetic field on the feed line 14 is expressed as a superposition of various electromagnetic field modes. The distribution of the traveling wave and the reflected wave of the voltage / current in the feed line 14 and the state of the standing wave accompanying the distribution are based on the distributed constant line theory. By associating the propagation constant and the wave impedance of each mode present in the feeder line 14 with the propagation constant and the characteristic impedance of the distributed constant line, it is also possible to extract the wave property of each mode.

  There are several modes that can exist in the feed line 14, and the most basic mode among them is the TEM. The TEM mode is a mode in which both the electric field and the magnetic field exist only in a section perpendicular to the propagation direction of the electromagnetic wave. The cutoff frequency in the TEM mode is 0. In other words, when a TEM mode can exist, it can propagate at all frequencies. In general, a TEM mode exists in a transmission line in which there are two or more conductors, that is, the feed line 14.

FIG. 9 is a model diagram when the power supply line 14 is viewed as a distributed constant line. FIG. 9A shows a distributed constant line model of the feed line 14. FIG. 9B illustrates a first-order lumped-constant circuit model of the distributed-constant line model. When the propagation direction is the positive direction of the z-axis, the minute section Δz of the feed line 14 is represented by a lumped constant. R, L, G, and C in FIG. 9 are defined as follows.
R: Series resistance per unit length L: Series inductance per unit length G: Shunt conductance per unit length C: Shunt capacitance per unit length

At this time, the characteristic impedance Z ₀ and the propagation constant γ are given by the following equations.
Z ₀ = {(R + jωL) / (G + jωC)} ^1/2 (2)
γ = {(R + jωL) (G + jωC)} ^1/2 (3)

Figure 10 is a model diagram when connecting the load impedance Z _L to the reception terminal (z = 0) of the distributed constant line model. When reception terminal the (z = 0) to the load impedance Z _L is connected, the reflection coefficient at the reception terminal Γ is expressed by the following equation.
_{Γ = (Z L -Z 0)} / (Z L + Z 0) ··· (4)

If the feed line is that it is lossless line, the power W _L transmitted actually to the load Z _L is given by the following equation input power as W _in.
W _L = (1− | Γ | ² ) W _in (5)

When gamma = 0, the load impedance Z _L is equal to the characteristic impedance of the distributed constant line model. At this time, no reflection occurs at the receiving end, and the load and the distributed constant line model are said to be matched. When the reflection coefficient に お け る at the receiving end is not 0 (Γ ≠ 0), a reflected wave returning from the receiving end to the incident end exists in the transmission line (feeding line 14). The reflected wave interferes with the incident wave to generate a standing wave. At this time, the ratio of the maximum value V _max of the voltage to the minimum value V _min of the voltage in the distributed constant line model is referred to as a voltage standing wave ratio (VSWR: Voltage Standing Wave Ratio).

  When VSWR is 1, no standing wave occurs in the distributed constant line model. The distance between adjacent maximum or minimum voltages is λ / 2, and the distance between the maximum and minimum voltages is λ / 4.

FIG. 11 is a diagram illustrating a case where the wavelength is λ / 4 with respect to the length of the distributed constant line model. In this case, the input impedance _{Z in is} converted Z _in ^{= Z} 0 2 / _{Z L,} and the load impedance _{Z L} to the inverse. At this time, when the power supply voltage and V _in, the voltage V _L and the current I _L in the load is as follows.
V _L = V _in · Z _L / (jZ ₀ ) (6)
_{I L = V in / (jZ} 0) ··· (7)

From the above equation, the length of the feed line 14, when a quarter of the wavelength λ of the switching frequency f _s, the impedance is a pure resistance, when connecting the load impedance Z _L described above impedance of the feed line 14 , The voltage on the load side rises. Therefore, a boosting transformer can be formed by the power supply line 14. For example, when Z ₀ = 50Ω and Z _L = 100Ω, the voltage doubles, and when Z ₀ = 50Ω and Z _L = 1000Ω, the voltage doubles. At this time, since noise cannot be impedance-matched, it is attenuated by reflected waves. Therefore, efficient power supply becomes possible.

  Next, a power supply system for the unmanned aerial vehicle 10 will be described.

  FIG. 12 is a block diagram of a power supply system for the unmanned aerial vehicle 10 using an AC power supply of a commercial power supply. The power supply unit 22 on the ground includes an AC power supply 40 that draws commercial power through an outlet, and a booster 44 that boosts the AC power supply 40. When a commercial power supply cannot be used, the AC power supply 40 may use a power generator such as a diesel generator. Electric power from the power supply unit 22 is transmitted to the unmanned aerial vehicle 10 via the power supply line 14.

  The unmanned aerial vehicle 10 is provided with an unmanned aerial vehicle power supply unit 24. In the unmanned aerial vehicle power supply unit 24, the power transmitted through the power supply line 14 is stepped down by the step-down unit 46, and is converted into a DC voltage by the rectifying bridge 48 and the smoothing circuit 50. The converted DC voltage is converted by a DC / DC converter 52 into a voltage suitable for the receiver 28, the flight control circuit 26, the device control circuit 30, the mounted device 32, and the sensor 38, and supplied. The propeller of the unmanned aerial vehicle 10 is rotated by, for example, a three-phase brushless DC motor. The rotation of the three-phase brushless DC motor is controlled by the motor drive waveform converted into three phases by the DC / AC inverter 54 and the ESC 36. Since the propeller is rotated by the three-phase brushless DC motor, the unmanned aerial vehicle 10 is controlled by the control of the three-phase brushless DC motor.

  Hereinafter, power transmission on the power supply line 14 using the AC power supply 40 will be described based on embodiments. The circuit configuration of the unmanned aerial vehicle 10 indicates a circuit up to the smoothing circuit 50 in the unmanned aerial vehicle power supply unit 24.

<Example 1>
FIG. 13 is a diagram illustrating a configuration of a power supply circuit when the commercial power is transmitted directly via the power supply line 14. The power supply unit 22 is an AC power supply 40 from an outlet or an engine generator. A voltage of 100 V is transmitted to the power supply line 14 at 50 or 60 Hz. In the unmanned aerial vehicle power supply unit 24, the AC power is converted into a DC voltage by a rectifying bridge 48 for rectifying the AC and a smoothing circuit 50. The rectifying bridge 48 includes four diodes D ₁ , D ₂ , D ₃ , and D ₄ , and the smoothing circuit 50 has a smoothing capacitor _Co connected in parallel.

<Example 2>
FIG. 14 is a diagram illustrating a configuration of a power supply circuit in which the power supply unit 22 is provided with a booster unit 44 and the unmanned aerial vehicle power supply unit 24 is provided with a step-down unit 46 in order to reduce loss in the power supply line 14. The step-up unit 22 uses a step-up transformer T ₁ , and the step-down unit 46 uses a step-down transformer T ₂ . AC voltage stepped down by the step-down transformer T ₂ are, are converted into DC voltage by the rectifier bridge 48 and the smoothing circuit 50.

  Commercial power transmitted in an urban area is transmitted at 6600 V in a transmission line in order to suppress power loss, and the voltage is reduced to 100 V by a transformer and supplied to ordinary households. In general, the power semiconductor of the power supply circuit has a withstand voltage of about 1 kV at present, but in order to suppress the power loss in the power supply line 14, power is supplied at an AC voltage of 1 kV or more, and the voltage is reduced by the step-down unit 46. By setting the voltage to be usable by the power semiconductor, efficient power supply becomes possible. For example, the voltage supplied to the power supply line 14 is set to 2 to 3 kV, and the voltage is reduced to 1 kV or less by the step-down unit 46. Such voltage conversion can be easily realized by a transformer in an alternating current.

<Example 3>
FIG. 15 is a diagram illustrating a configuration of a power supply circuit when AC power is transmitted in a single-phase three-wire system. An AC power supply 40 is a commercial power source, it is converted into the single-phase three-wire system by transformer T _3. And a neutral line from the center of the secondary winding of the transformer T ₃ Pull the feed line 14. The upper and lower power supply lines 14 have a voltage of 100 V in opposite phase with respect to the neutral wire, and the voltage is 200 V when voltage is taken out from the upper and lower power supply lines. In the circuit configuration shown in FIG. 15, the neutral wire is grounded by the unmanned aerial vehicle power supply unit 24, and the voltage is taken out as 200 V from the upper and lower feeder lines. In the case of the single-phase three-wire system, no current flows through the neutral wire, so that the voltage drop in the power supply line 14 can be suppressed to ４ of that in the case of the single-phase two-wire system.

<Example 4>
FIG. 16 is a diagram illustrating a configuration of a power supply circuit for transmitting three-phase power via the power supply line 14. FIG. 16A shows a circuit configuration for directly transmitting three-phase power via the power supply line 14. The power supply unit 22 receives a commercial three-phase AC power supply 58 and transmits power via the power supply line 14. FIG. 16B shows a circuit configuration obtained by converting a single-phase AC power supply 40 into three phases by a converter 60. As shown in FIG. 16B, the three-phase AC power supply 58 may be converted from a single-phase AC power supply 40 into three phases by the converter 24, or may be generated by an engine generator. In the unmanned aerial vehicle power supply unit 24, a three-phase AC is provided by a rectifying bridge 48 including six diodes D ₁ , D ₂ , D ₃ , D ₄ , D ₅ , and D ₆ and a smoothing capacitor _Co of a smoothing circuit 50. The voltage is converted to a DC voltage. In the three-phase AC voltage, the phases of the three AC voltage waveforms are shifted by 120 degrees, the pulsating current in the rectifying bridge is smaller than that of the single-phase AC voltage, and the DC voltage can be efficiently converted.

  Next, transmission of a switching waveform on a power supply line using a circuit configuration of a switching power supply will be described. The switching waveform is mainly used in a middle frequency region and a high frequency region.

  FIG. 17 is a block diagram of a power supply system relating to the unmanned aerial vehicle 10 when a switching waveform is transmitted through the power supply line 14. In the power supply unit 22, a switching waveform in which the DC power supply 62 is turned on and off by the chopper circuit 60 is generated, and the generated switching waveform is sent to the power supply line. The DC power supply 62 may be a power supply using an AC / DC converter that converts alternating current (AC) into direct current (DC).

  The switching waveform generated by the chopper circuit is converted into a DC voltage by the smoothing circuit 50 of the unmanned aerial vehicle power supply unit 24 in the unmanned aerial vehicle 10. The converted DC voltage is converted by a DC / DC converter 52 into a voltage suitable for the receiver 28, the flight control circuit 26, the device control circuit 30, the mounted device 32, and the sensor 38, and supplied. What rotates the propeller of the unmanned aerial vehicle 10 is, for example, a three-phase brushless DC motor. The rotation of the propeller is controlled by the motor drive waveform converted by the DC / AC inverter 54 into three phases and the motor control by the ESC 36. The power transmission of the unmanned aerial vehicle 10 through the power supply line 14 using the DC power supply 62 will be described based on an embodiment. The circuit configuration of the unmanned aerial vehicle 10 indicates a circuit up to the smoothing circuit 50 in the unmanned aerial vehicle power supply unit 24.

<Example 5>
FIG. 18 is a diagram showing a configuration of a power supply circuit that converts a DC power supply 62 into a three-phase AC power supply by a chopper circuit 60 and transmits the power to the power supply line 14. The DC power source 62, an input capacitor _{C in} is connected in parallel. The chopper circuit 60 includes three high-side switching elements SW ₁ , SW ₃ , and SW ₅ and three low-side switching elements SW ₂ , SW ₄ , and SW ₆ . The high-side switching element SW ₁ and the low-side switching element SW ₂ , the high-side switching element SW ₃ and the low-side switching element SW ₄ , the high-side switching element SW ₅ and the low-side switching element SW ₆ are connected in series, respectively, and their respective series circuits are connected. Is controlled to turn on / off the high-side switching element and the low-side switching element by shifting the phase by 120 degrees. Thereby, a three-phase AC waveform is generated.

The voltage used in the unmanned aerial vehicle 10 is about several tens of volts. An on-board battery of an EV (Electric Vehicle) has a high DC voltage of about 500 V, and therefore, the voltage from the on-board battery can be directly converted into a three-phase AC waveform and sent to the power supply line 14. In unmanned air supply unit 24, by the smoothing capacitor _{C 0} of the rectifier bridge 48 and a smoothing circuit 50 for a three-phase alternating current composed of diodes _D 1 to D _6, are converted into DC voltage.

For the transmission of power on the power supply line 14 using the switching waveform, various DC / DC converter circuit configurations can be used. The DC / DC converter has a circuit configuration in which a switching voltage is generated from a DC voltage by a switching element, and a desired DC voltage is obtained by smoothing. Switching is an operation to turn on and off the switching element SW by the switching frequency f _s, can boost-buck voltage, there is a synchronous and asynchronous.

  Hereinafter, power transmission on the power supply line 14 using the DC power supply 62 will be described based on embodiments. The circuit configuration of the unmanned aerial vehicle 10 indicates a circuit up to the smoothing circuit 50 in the unmanned aerial vehicle power supply unit 24.

<Example 6>
FIG. 19 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on the power supply line 14 using the circuit configuration of the step-down DC / DC converter. FIG. 19A shows a configuration in which a circuit configuration of an asynchronous step-down DC / DC converter is used. DC voltage because a DC power source 62 is turned on and off at a switching frequency _{f s} by the switching element SW. The switching waveform generated here is transmitted to the smoothing circuit 50 of the unmanned aerial vehicle power supply unit 24 via the power supply line 14. The smoothing circuit 50 includes an inductor L _O connected in series and a smoothing capacitor C _O connected in parallel.

FIG. 19B is a diagram in a case where a circuit configuration of a synchronous step-down DC / DC converter is used. Synchronous, the switching elements SW ₁ and the switching element SW ₂ in the chopper circuit is turned on and off in synchronism with the switching frequency f _s. The smoothing circuit 50 is the same as the asynchronous type.

In the mid-frequency region, the switching frequency f _s, it is necessary to set in consideration of the frequency characteristic of the feed line 14. The power supply line 14 has frequency characteristics, and its transmittable frequency is limited by a cutoff frequency. Therefore, the switching frequency f _s is, it is required is less than the cutoff frequency of the feed line 14, noise, taking advantage of the frequency characteristic of the feed line 14, the frequency of the noise is cut-off frequency of the feed line 14 If it is above, it will be attenuated by the feeder line 14, and the feeder line 14 can be used effectively. The frequency of the noise is high, and the main sources are the parasitic inductance and ESR (equivalent resistance) depending on the wiring pattern of the circuit board in the power supply unit 22, and the parasitic capacitance of the switching element.

FIG. 20 is a diagram showing an equivalent circuit in the circuit of the power supply unit 22 shown in FIG. 19B in consideration of parasitic inductance and parasitic capacitance. Since the switching element depends on the type of the element to be selected, where the power MOSFET, and the high-side switching element SW ₁ and the low-side switching element SW ₂ and power MOSFET.

The parasitic elements are the parasitic inductance L _S1 and ESR (Equivalent Serial Resistance) _in the input capacitor C _in . ESR also exists in the wiring, and is collectively referred to as ESR ₁ in FIG. In the power MOSFET, the body diode and the parasitic capacitance were used as parasitic elements without considering the Miller capacitance and the gate capacitance. In the high-side switching element SW _1, shows a parasitic capacitance _{C S1} and the body diode _{D S1,} the low-side switching element SW _2, the equivalent circuit the parasitic capacitance _{C S2} and the body diode _{D S2} as a parasitic element.

Parasitic inductance also occurs in wiring, layout, vias, etc., but is shown in FIG. 20 by wiring parasitic inductances L _S2 , L _S3 , and L _S4 .

On and off the high-side switching element SW ₁ and the low-side switching element SW ₂ is controlled by a gate drive signal, the noise is mainly the high-side switching element SW ₁ and the low-side switching element SW ₂ is generated when the off easy. When the high-side switching element SW ₁ is turned on, through the high-side switching element SW ₁ from the DC power source 62, current flows to the return current of the low-side switching element SW ₂ to cancel.

The recovery function the current of the low side switching element SW ₂ is the low-side switching element SW ₂ of the body diode D _S2 also becomes zero has a reverse current flows through the body diode D _S2 until no carriers stored. The recovery current is input capacitor C _in, a short circuit current i flowing through the loop comprising the high side switching element SW ₁ and the low-side switching element SW _2, energy is stored in all the parasitic capacitance present in the loop.

This energy is released at the moment when the recovery does not work. At this time, resonance occurs in the parasitic inductance and the parasitic capacitance in the loop, causing surge or ringing, thereby generating noise. Since the high-side switching element SW ₁ is turned in the on state, the parasitic capacitance C _S1 of the high-side switching element SW _1, regardless the frequency of the high frequency ringing, the resonant frequencies of all of the parasitic inductance and capacitance of the loop is there.

The high-side switching element SW ₁ and the low-side noise during the OFF switching element SW ₂ is typically several hundred MHz, the input capacitor _{C in} a current surge high di / dt, the high-side switching element SW ₁ and the low-side switching element circulating in the high-frequency ringing loop of SW _2. Thus, the input to the capacitor _{C in} the surge voltage is generated which depends on the di / dt, the high-side switching element SW ₁ and the low-side switching element SW ₂ is ringing dV / dt corresponding to the voltage V of the DC power supply 62 Voltage is generated. The high-frequency ringing current flowing through the loop generates a magnetic flux depending on the area of the loop, and the magnetic flux is radiated to the outside, so that electromagnetic waves are induced as electromagnetic waves in the strip line or loop of the board of the device.

  As described above, the noise generated in the power supply unit 22 has a high frequency, and can be sufficiently attenuated by selecting the power supply line 14 in consideration of the frequency characteristics. Transmission of the switching waveform on the power supply line 14 using the circuit configuration of the DC / DC converter is effective in other circuit configurations.

FIG. 21 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on the power supply line 14 by using a circuit configuration of an asynchronous boost DC / DC converter. The chopper circuit 60 includes an inductor L, a diode D, and a switching element SW. A synchronous configuration may be used with the diode D as a switching element. The smoothing circuit 50 in the unmanned aerial vehicle power supply unit 24 has a circuit configuration in which a smoothing capacitor _CO is connected in parallel. When the switching element SW is turned on and off, energy is stored in the inductor when the switching element SW is on, and the energy stored in the inductor is released via the diode D when the switching element SW is off, thereby boosting the voltage. The diode D may be a synchronous type in place of the switching element SW. The configuration of the boosting type power supply circuit is effective when the voltage of the DC power supply 62 to be used is low.

FIG. 22 is a diagram illustrating a configuration of a power supply circuit in a case where power transmission is performed on the power supply line 14 using a circuit configuration of a flyback type DC / DC converter. The power supply circuit uses a circuit configuration of a flyback type DC / DC converter. The chopper circuit 60 includes a transformer T and a switching element SW. The switching element SW turns on and off a DC voltage from the DV power supply 62 via the transformer T. The primary winding wound around the core of the transformer T is connected to the drain of the switching element SW. The primary and secondary sides of the transformer T have opposite polarities as indicated by dots. The secondary side of the transformer T is connected to the power supply line 14. The smoothing circuit 50 in the unmanned aerial vehicle power supply unit 24 includes a diode D connected in series and a smoothing capacitor _CO connected in parallel.

  When a gate voltage is applied to the gate of the switching element SW and the switching element SW is turned on, a primary current flows through the primary winding. When the primary current flows, a magnetic flux is generated in the core of the transformer T, and the core is magnetized to store energy. At this time, on the secondary side, the direction of the diode D connected via the power supply line 14 is reversed, so that the secondary side current does not flow on the secondary side.

When the switching element SW is turned off due to the cutoff of the gate voltage, the primary current does not flow, and the switching element voltage of the switching element SW is in a state where the voltage of the DC power supply 62 is directly applied. The energy stored in the core of the transformer T is released and flows from the secondary winding toward the diode D. When all the energy is released, that is, when the secondary current becomes zero, the gate voltage of the switching element SW is applied again to turn on the switching element SW. Since the primary winding and the secondary winding of the transformer T have the function of a choke coil, there is a feature that noise is hardly generated. Therefore, the GaN-HEMT is used as the switching element SW for the purpose of increasing the frequency. The GaN-HEMT is a power device that has a high withstand voltage and can operate at high speed. The switching element SW may be an element made of a SiC transistor in addition to a GaN transistor. These fast power semiconductors, and some switching frequency f _s is available than 1 MHz.

FIG. 23 is a diagram illustrating a configuration of a power supply circuit in the case where power transmission is performed on the power supply line 14 using the circuit configuration of the forward DC / DC converter. The chopper circuit 60 includes a transformer T and a switching element SW, and the switching element SW turns on / off the DC voltage from the DC power supply 62 via the transformer. The primary winding wound around the core of the transformer T is connected to the drain of the switching element SW. The primary and secondary sides of the transformer T have the same polarity as shown by the dots. The secondary side of the transformer T is connected to the power supply line 14. Smoothing circuit 50 on the unmanned air vehicle power supply unit 24 includes a diode D ₁ connected in series, and a parallel-connected commutation diode D ₂ and a smoothing capacitor C _O.

When a gate voltage is applied to the gate of the switching element SW and the switching element SW is turned on, a primary current flows through the primary winding. Flows primary current, magnetic flux is generated in the core of the transformer T, secondary side, the diode D ₁ connected via a feed line 14 passing a secondary current, the current to the smoothing capacitor C _O Supply. When turned off by the interruption of the gate voltage, the primary current does not flow, energy stored in the core of the transformer T supplies a current to the smoothing capacitor C _O via the diode D _2. The forward type is a type in which the transformer is excited in only one direction, and has a feature that noise is unlikely to be generated as in the flyback type.

FIG. 24 is a diagram showing the configuration of a power supply circuit in the case where power transmission is performed by using the circuit configuration of the forward DC / DC converter instead of the transformer T with the power supply line 14. The chopper circuit 60 has no transformer T, and the DC power supply 62 and the drain of the switching element SW are connected to the power supply line 14. Smoothing circuit 50 is similar to the circuit shown in FIG. 23, the receiving end of the feed line 14, connects the load impedance Z _L in parallel.

In the high frequency region, can not be ignored length of the feed line 14 to the switching frequency, for example, the feed line 14 of length 100 m, the speed of light as 3 × ¹⁰ 8 m / s, the wavelength corresponding to the switching frequency _{f s} If λ is the length of the feed line 14, the switching frequency is 3 MHz. The length of the feed line 14, the lambda / 4 impedance matching, since the wavelength is four times the switching frequency _{f s} is 750 kHz. Also the length of the feed line 14 as 3000 m, considering the alignment of the lambda / 4, the switching frequency _{f s} is 1 MHz. FIG. 24 schematically shows the length of the power supply line 14 and the state of λ / 4 matching of the switching waveform.

As described above, when the length of the power supply line 14 and the wavelength of the switching waveform are matched at λ / 4, the voltage at the load becomes Z _L / Z ₀ times the voltage of the DC power supply 62, and This produces the same effect as. Therefore, when the power supply circuit is configured using the circuit configuration of the forward DC / DC converter, a power supply circuit having the power supply line 14 as the transformer T instead of the transformer T can be configured. As a result, the transformer T can be eliminated. Since energy is not stored in the power supply line 14, the transformer T cannot be used in the power supply circuit using the flyback type DC / DC converter.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the spirit of the present invention.

f frequency _{f s} switching frequency λ wave V voltage I current W power _{W los} power loss R feed line equivalent resistance Γ reflection coefficient _{Z in} the input impedance _{Z 0} characteristic impedance _{Z L} load impedance _{D, D 1, D 2,} D 3, D _{4, D} 5, _{D 6} diodes _{C O} smoothing capacitor _{C in} the input capacitor _{T, T 1, T 2,} T 3 trans _{SW, SW 1, SW 2,} SW 3, SW 4, SW 5, SW 6 switching elements L, L _O inductor 10 unmanned air 12 base station 14 feeder line 16 take-up unit 18 propoxycarbonyl transmitter 20 ground power supply unit 22 power supply unit 24 unmanned air supply unit 26 the flight controller 28 receiver 30 device control unit 32 mounted device 34 Motor 36 ESC
38 Sensor 40 Single-phase AC power supply 42 Three-phase AC power supply 44 Boost unit 46 Step-down unit 48 Rectifier bridge 50 Smoothing circuit 52 DC / DC converter 54 DC / AC converter 56 Boost unit 58 Three-phase AC power supply 60 Chopper circuit 62 DC power supply

Claims (18)

A ground power supply for supplying power to the unmanned aerial vehicle,
An unmanned aerial vehicle power supply unit for supplying power to the motor and the electronic device of the unmanned aerial vehicle,
A power supply line connecting the ground power unit and the unmanned aerial vehicle power unit,
With
Supply power supplied from the ground power supply unit to the unmanned aerial vehicle power supply unit through the power supply line has a periodic voltage or current waveform,
A wired powered unmanned aerial vehicle characterized by the following. The power supply is a single-phase AC power,
The wire-powered unmanned aerial vehicle according to claim 1, wherein: The power supply line is a single-phase three-wire system;
The wire-powered unmanned aerial vehicle according to claim 2, characterized in that: The supply power is three-phase AC power;
The wire-powered unmanned aerial vehicle according to claim 1, wherein: The single-phase AC power or the three-phase AC power is AC power from a commercial power supply,
The wire-powered unmanned aerial vehicle according to claim 2 or 4, wherein: The three-phase AC power has been converted from the single-phase AC power,
The wire-powered unmanned aerial vehicle according to claim 4, characterized in that: A booster is provided in the ground power supply,
AC power from the commercial power supply is boosted by the booster, and is supplied to the unmanned aerial vehicle power supply via the power supply line,
The wire-powered unmanned aerial vehicle according to claim 5, characterized in that: A DC / AC inverter or an AC / AC converter is provided in the ground power supply unit, and an AC / DC converter, DC / DC and DC / AC inverter are provided in the unmanned aerial vehicle power supply unit;
The wire-powered unmanned aerial vehicle according to claim 1, wherein: The output waveform of the supply power is a switching waveform,
The wire-powered unmanned aerial vehicle according to claim 1, wherein: The cutoff frequency of the power supply line is higher than the switching frequency of the switching waveform,
The wire-powered unmanned aerial vehicle according to claim 9, characterized in that: The power supply line has a function of removing noise from the switching waveform,
The wire-powered unmanned aerial vehicle according to claim 9, characterized in that: A wavelength corresponding to the switching frequency is １ ／ of a length of the power supply line;
The wire-powered unmanned aerial vehicle according to claim 9, characterized in that: The switching waveform is an output waveform of a chopper circuit;
The wire-powered unmanned aerial vehicle according to claim 9, characterized in that: The switching waveform is a transformer output waveform of an isolated converter,
The wire-powered unmanned aerial vehicle according to claim 9, characterized in that: The switching element of the chopper circuit or the insulation type converter is an element including a GaN transistor or a SiC transistor,
The wire-powered unmanned aerial vehicle according to claim 13, wherein: The unmanned aerial vehicle power supply unit is provided with a smoothing circuit,
The wire-powered unmanned aerial vehicle according to claim 9, characterized in that: The ground power supply unit includes an in-vehicle battery,
The wire-powered unmanned aerial vehicle according to claim 1, wherein: The ground power unit includes an engine generator,
The wire-powered unmanned aerial vehicle according to claim 1, wherein: