UNIVERSAL AERIAL POWER SUPPLY SYSTEM FOR A TETHERED SMALL UNMANNED AERIAL VEHICLE

Abstract

An electrical power supply system for a tethered small unmanned aerial vehicle has a ground station (1) connected to a universal aerial power supply (13) by a tether (10). The universal aerial power supply is capable of installation into the battery dock of a conventional free flying small unmanned aerial vehicle to deliver power to the small unmanned aerial vehicle systems during flight. The universal aerial power supply is compatible with a range of different small unmanned aerial vehicles and a range of classes of small unmanned aerial vehicles.

Claims

1. An electrical power supply system for a small unmanned aerial vehicle comprising: a ground station including an electrical power supply to deliver power to a tether; a connector to electrically connect a ground end of the tether to the ground station and having an aerial power supply to mechanically and electrically connect to a small unmanned aerial vehicle power dock, wherein the aerial power supply has a connector to enable an airborne end of the tether to be separably connected to the aerial power supply and the ground station has a connector to enable the ground end of the tether to be separably connected, wherein the aerial power supply includes a small unmanned aerial vehicle DC-DC converter; said ground station adapted to deliver a selected one of a range of discrete voltages to the connected tether whereby the voltage delivered by the aerial power supply to the small unmanned aerial vehicle is determined by the voltage applied to the tether so that the aerial power supply can deliver the power demand to any of a range of small unmanned aerial vehicles having differing power requirements.

2. A system according to claim 1 wherein the voltage applied to the tether is selected by means of a switch.

3. A system according to claim 1 wherein the switch is manually operable.

4. A system according to claim 1 wherein, each tether for use with the system is wired with a similar multi pin connector for connection to corresponding connector parts at each of the ground station and the aerial power supply, so that power can only be delivered to the tether and aerial power supply when the ground station output voltage selected is compatible with the tether connected to the ground station.

5. A system according to claim 4 wherein the connector parts each comprise electrically connectable pins, each tether for said system having a conductor wired to a common pin, each tether for a specific class of small unmanned aerial vehicle having a live conductor wired to a class specific pin exclusive to the class.

6. A system according to claim 5 wherein a first pin is the common pin, a second pin is exclusively wired to the live conductor in a class one tether, a third pin is exclusively wired to a live conductor in a class two conductor, and a fourth pin is wired to a live conductor in a class three tether.

7. A system according to claim 1 wherein each conductor pin of a ground station part of a tether connector is connected to a high voltage output of a ground DC-DC converter.

8. A system according to claim 7 wherein each conductor pin of a ground station part of a connector is connected to a high voltage output from the ground DC to DC converter.

9. A system according to claim 8 wherein the low voltage input to the ground DC-DC converter is connected to an output of a voltage adjustment circuit arranged to adjust a source voltage to one of a predetermined set of voltages in response to operation of the switch.

10. A system according to claim 9 wherein the predetermined voltages include 11.1V, 14.8V and 22.2V.

11. A system according to claim 10 wherein the ground DC-DC converter elevates the predetermined voltage by a factor of 16 to apply a tether voltage of 177.6V for a class 1 tether, 236.8V for a class 2 tether and 355.2V for a class three tether.

12. A system according to claim 9 wherein the switch is arranged to set the voltage adjustment circuit output in accordance with the tether selection.

13. A system according to claim 1 wherein the aerial power supply has an adapter interface to emulate a proprietary smart battery interface.

14. A system according to claim 1 wherein the aerial power supply has cooling system.

15. A system according to claim 14 wherein the cooling system is an air cooling system wherein a powered fan forces a flow of air around a casing of the universal power supply.

16. A system according to claim 1 wherein the casing of the aerial power supply is adaptable to engage with a battery dock of the small universal aerial vehicle.

17. A system according to claim 1 wherein the aerial power supply includes a backup battery to provide power in the event of the tether supply failing.

18. A system according to claim 7 wherein the ground station is provided in an enclosure including the tether connector part, switch, ground DC-DC converter and voltage adjustment circuit and a rectifier module to deliver DC to the voltage adjustment circuit, AC being deliverable to the rectifier via a connector in the enclosure connectable to an external AC source.

19. A system according to claim 18 including an inverter arranged to connect to the AC connector in the ground station and having a DC connector adapted to connect to a 12V, 24V or 48V DC source.

20. A system according to claim 19 wherein the inverter is provided in an enclosure separate from the ground station.

21. A system according to claim 20 wherein the ground station has separable connectable modules comprising: a rectifier module to transform an alternating current supply to a direct current supply for application to the tether; an inverter module separably connectable to the rectifier module, whereby direct current from a direct current source can be converted to an alternating current compatible with the rectifier module; and, a battery module comprising a battery of charge storage devices separably connectable to the inverter module.

22. A system according to claim 1 wherein the aerial power supply comprises a aerial power supply connector part of an electrical connector to connect to a corresponding tether connector part, said small unmanned aerial vehicle connector part delivering current in parallel to two or more DC-DC converter modules in order to distribute heat generation and thereby relatively reduce the operating temperature of the aerial power supply.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of a power supply system for a small unmanned aerial vehicle constructed in accordance with the present invention will now be described, by way of example only, with reference to the accompanying figures, wherein:

[0030] FIG. 1.1 is a diagram of a ground station connector of a first embodiment;

[0031] FIG. 1.2 is a diagram of wiring for a class 1 tether of the first embodiment;

[0032] FIG. 1.3 is a diagram of wiring for a class 2 tether of the first embodiment;

[0033] FIG. 1.4 is a diagram of wiring for a class 3 tether of the first embodiment;

[0034] FIG. 1.5 is a diagram of wiring for a aerial power supply of the first embodiment ;

[0035] FIG. 2 is a diagram of the system of a second embodiment;

[0036] and

[0037] FIG. 3 is a diagram of a third embodiment.

DETAILED DESCRIPTION OF DRAWINGS

[0038] FIG. 1 is a diagram of a first embodiment of a system having a ground station indicated by arrow 1 provided in a case 2. The housing provides a weather proof enclosure for the ground station components which include a battery of rechargeable chemical cells 3, 4 capable of delivering 12V or 24V according to the setting of a switch 5. It may be noted that in variants of the embodiment the 12V or 24V supply may be external, via an electrical connector, and provided, for example, by a vehicle low voltage circuit so the small unmanned aerial vehicle can be powered by the vehicle. Where an internal battery is provided the battery is preferably of rechargeable chemistry and capable of charging via a conventional charging circuit from grid power using technology well known in the art.

[0039] The battery applies a voltage to a DC to DC converter via a voltage adjustment circuit 6 which may adjust the voltage by conventional resistive circuity to output any one of 11.1V, 14.8V or 22.2V. Switch may be manually operable or responsive to other system components as described below. The selected voltage is applied to a DC-DC converter 7, for example, selected from one of the DCM family of DC to DC convertors offered by Vicor®. The converter serves to increase circuit voltage applied to a selected pin 8.2 of a connector 8.0 from nominally 11.1V to 177.6V. A suitable connector 8.0 may be provided by the Jaeger 3 Way Cable Mount MIL Spec Circular Connector Plug, Socket Contacts, MIL-DTL-5015. As illustrated this has seven pins (seven way) or sockets 8.1-8.7 and a housing configured to connect in only one orientation. In the specific example only four pins are used so in practice a four way connector would serve. Ground station connector part 8.0 will be described as having pins 8.1-8.7 for cooperation with a corresponding tether connector part 9.0 attached to a tether 10 having at least two current carrying conductors 10.1 and 10.2. Pin 8.1 is always connected to the common, negative or earth. Pin 8.2 is wired to terminal 2 of a three way switch 11, such that in the condition illustrated 177.6 V is applied to pin 8.2. Pin 8.3 is wired to terminal 3 so that when circuit 7 is switched to deliver 14.8 V to the DC-DC converter 236.8V is applied to pin 8.3. Pin 8.4 is wired to terminal 4 of switch 11 so that when circuit 7 is switched to deliver 22.5V to the DC-DC converter 355.2V is applied to pin 8.4. Whichever pin is live the other pins are open circuit.

[0040] FIGS. 1.2-1.4 illustrate wiring for three classes of tether. Each tether has two conductors which are designated common 10.1 and live 10.2. A ground station connector part 9 and aerial power supply connector part 12 are connected to the conductors as follows:

TABLE-US-00001 small unmanned ground station aerial vehicle Tether class conductor connector pin connector pin 1 10.1 9.1 12.1 10.2 9.2 12.2 2 10.1 9.1 12.1 10.2 9.3 12.3 3 10.1 9.1 12.1 10.2 9.4 12.4

[0041] Thus it is not possible to mismatch tether classes and supply voltage, because if switch 11 is incorrectly set no voltage will be applied to the conductor 10.2.

[0042] Conveniently the voltage circuit 6 may be driven in response to the position of switch 11.

[0043] The system provides a aerial power supply 13. aerial power supply 13 has a case 14 adapted to cooperate with a power supply dock “D” provided in the small unmanned aerial vehicle. Cooperate should be understood to mean that the case includes electrical terminals located to communicate with the electrical terminals in the dock D and that the aerial power supply case is shaped and sized to be secured closely into the dock D using whatever mechanical securing devices are compatible with dock D. The case 14 will present a aerial power supply connector part 15 compatible with the tether connector part 12 whereby the tether can be mechanically and electrically connected. Connector 15 has a first pin 15.1 wired to communicates with the pin 12.1 and with a common terminal on a aerial power supply DC-DC converter 16 which is mounted into the case 14. Pins 15.2, 15.3 and 15.4 are each in electrical communication with a live terminal of the DC-DC converter. Thus the voltage applied to the DC to DC converter is determined by the tether and ground station. The output voltage from the DC to DC converter in the example will be one sixteenth of the applied voltage, ie for a class 1 tether, 11.1V, for class 2 tether, 14.8V and for class 3 22.5V. It will be appreciated that these are nominal voltages and in practice these can vary within tolerance limits according to the conditions of operation of the small unmanned aerial vehicle, such as temperature and other factors.

[0044] With the voltages at the aerial power supply DC to DC converter stepped down to small unmanned aerial vehicle compatible voltages the voltage is applied to the small unmanned aerial vehicle systems.

[0045] Some small unmanned aerial vehicles require a smart battery power pack. This commonly incorporates circuitry to determine the condition of the battery pack in terms of factors such as charge state, temperature, voltage output etc. This is then applied to the small unmanned aerial vehicle control system (17) which will respond by enabling or disabling the small unmanned aerial vehicle for service. The aerial power supply includes a smart service emulator 18 which imitates the signals which would otherwise be delivered from a smart battery pack in order to enable the small unmanned aerial vehicle for service.

[0046] The aerial power supply also includes a backup battery 19 which is charged from the DC-DC converter. In the event the tether supply fails the backup battery 19 can provide sufficient power to enable the small unmanned aerial vehicle to land safely.

[0047] Although only illustrated in FIG. 2 the aerial power supply may also include a cooling system 20 in this case shown as a cooling fan arranged to circulate air through the aerial power supply casing and thereby cool the aerial power supply components. In variants of the embodiments the cooling system may be provided by heat pipes and or heat sinks alone or combination with a cooling fan. This is more important for tethered small unmanned aerial vehicle's because they are capable of and likely to be used for prolonged periods of hovering/motionless flight so that the cooling effect of movement through air is attenuated relative to an untethered small unmanned aerial vehicle.

[0048] FIG. 2 illustrates a second embodiment of the system wherein the ground station is configured to be modular. The ground station has an AC power module 21 with an enclosure presenting a connector 8 similar to the connector 8 of the first embodiment, and connected to a contained circuit 6 and switch 11. However, circuit 6 draws power from an AC rectifier in the enclosure which in turn draws power from an AC source. In order to draw power the enclosure may include conventional electrical AC power connectors, preferably all-weather connectors. The AC grid source can be either of a 240V or 110 V AC source. In either case the current is rectified to 400V DC before being stepped down in circuit 6 to the standard tether voltages described previously. The aerial power supply is the same as the previously described aerial power supply.

[0049] This allows the small unmanned aerial vehicle to be powered from a distributed power grid or from a free standing generator.

[0050] An inverter module 22 is provided in a case to deliver AC power at 110V or 240V from a DC source at 12V or 24V. The inverter module includes a DC connector to facilitate connection to a DC power source such as a 12V, 24V or 48 V battery or a vehicle low voltage system.

[0051] A free standing battery pack 23 is provided capable of being plugged into the inverter module 22 and when the inverter module is plugged into the AC module 21 in order to deliver power from a low voltage, ie 12V or 24V battery to power the small unmanned aerial vehicle.

[0052] The third embodiment differs from the first and second embodiment in that the aerial power supply includes two or more DC-DC converters 16.1, 16.2 connected to the connector part 15 in parallel. This helps to reduce the current flowing through either of the two converters and thereby distribute the heat generated and keep temperature down. The other components of the system are essentially the same as aerial power supply 13 in the first and second embodiments with wiring changes as will be evident to the person skilled in the art.