Battery operated power unit and method for supplying power to external equipment

Abstract

A power unit 1 for supplying power to a variety of interchangeable external equipment 100, 200 includes a battery 10 for storing the power, electrical input and output connectors 11, 12 and control sy

Description

Technical Field [0001J A power unit, often referred to as an industrial open power unit or industrial power unit, is a self-contained power supply system that is interchangeably connectable to a variety of different external equipment to supply power to the external equipment. Background

[0002] Such external equipment may be either fixed or mobile and may be designed for various different applications in industrial, agricultural, transportation, healthcare, and other fields of use.

[0003] Conveniently, by designing such external equipment without an integral power supply unit or prime mover, the manufacturer of such external equipment can avoid the added complexity of designing and manufacturing the power supply or prime mover in-house, concentrating instead on the function of the external equipment, while offering a choice of power supply or prime mover to the end user of the equipment.

[0004] Conventional power units include an internal combustion engine, typically a diesel engine on larger units, and sometimes a gasoline (petrol) engine on smaller units. The unit may provide shaft power from the engine crankshaft to the external equipment, or can be arranged as a genset including an alternator driven by the engine to provide electrical power via AC or DC power output connnectors to the external equipment. The engine and alternator may be mounted on a fixed or wheeled chassis together with a fuel tank for storing fuel for the engine. The unit may also be fitted to another piece of mobile machinery or road going chassis.

[0005] Such power units produce exhaust gas emissions from the engine, which is undesirable in some applications.

[0006] This problem is avoided by electric power units, comprising a rechargeable battery, a battery charge control system for charging the battery from an external power source, and an output power control system including an inverter for supplying power from the battery via the power output connectors to the external equipment.

[0007] Hybrid power units are also available which combine a battery with an internal combustion engine powered genset, wherein the output power supply may be provided from the generator and / or via an inverter from the battery, which may also supply power to start the engine.

[0008] An electrical or hybrid power unit may be mounted for example on a skid chassis or on road wheels so that it can be towed behind a road vehicle between a point of use and a replenishment point at which the fuel tank or battery can be replenished. Summary of the Disclosure

[0009] In accordance with the present disclosure there is provided a power unit, being interchangeably connectable to a variety of different external equipment to supply power to the external equipment.

[0010] The power unit includes a battery, at least one power input connector, and at least one power output connector.

[0011] The power unit further includes a battery charge control system for charging the battery with electrical power supplied from an external power source via the power input connector, and an output power control system for supplying electrical power from the battery to the external equipment via the power output connector.

[0012] The power unit further includes at least one output shaft having an output shaft coupling for connecting the output shaft to an input shaft coupling of the external equipment, and at least one electric motor powered by the battery for driving the at least one output shaft in rotation.

[0013] The power unit further includes a control signal connector, and a motor control system for controlling operation of the electric motor responsive to control signals received from the external equipment via the control signal connector.

[0014] In another aspect, the disclosure provides a method of supplying power to external equipment by means of the power unit.

[0015] The method includes connecting the output shaft via the output shaft coupling to an input shaft coupling of the external equipment; connecting the motor control system via the control signal connector to the external equipment; and controlling operation of the electric motor, by the motor control system, to drive an input shaft of the external equipment in rotation, responsive to control signals received from the external equipment via the control signal connector. Brief Description of the Drawings

[0016] Further features and advantages will be appreciated from the illustrative embodiments that will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which: Figs. 1 and 2 show a power unit in front and rear end view, respectively. Fig. 3 is a schematic side view of the power unit showing the internal components. Fig. 4 is an external side view of the power unit showing the chassis mount fasteners. Fig. 5 is a bottom view of the power unit showing the chassis mount fastener positions. Fig. 6 illustrates a method of use of the power unit. Figs. 7 and 8 show a first external equipment in side and rear view, respectively. Figs. 9 and 10 show a second external equipment in side and rear view, respectively. Fig. 11 shows the first external equipment coupled to the power unit and mounted on a skid support. Fig. 12 shows the first external equipment coupled to the power unit, wherein the power unit is configured as a road trailer. Fig. 13 shows the power unit mounted on a support, wherein the support is configured as a road trailer. Fig. 14 shows the assembly of Fig. 13 with the second external equipment coupled to the power unit and mounted on the platform. Detailed Description

[0017] Referring to Figs. 1 - 5, in accordance with an embodiment of the disclosure, the power unit 1 is interchangeably connectable to a variety of different external equipment to supply power to the external equipment.

[0018] By external equipment is meant an equipment separate from and external to the power unit 1, and connectable to the power unit 1.

[0019] By way of example, Figs. 7 and 8 illustrate a first external equipment configured as a hydraulic power supply unit, including a shaft driven pump (not shown) supplying hydraulic fluid under pressure to hydraulic fluid hose connectors. Hydraulic tools may be connected to the hose connectors so as to power the tools on-site.

[0020] Figs. 9 and 10 illustrate a second external equipment configured as an agricultural cutting or shredding machine having a shaft driven cutter or screw (not shown) at the bottom of a hopper. Agricultural waste or plant material can be deposited in the hopper so as to obtain the comminuted material at the chute.

[0021] Both first and second external equipments include an input shaft coupling 122 for driving, respectively, the pump or cutter, and a controller that generates control signals 32 which are transmitted via a control signal output connector.

[0022] A body 101 of the external equipment is configured for connection to a conventional power unit driven by an internal combustion engine (ICE), conveniently via an SAE standard interface for connection to the engine flywheel housing of the engine. The input shaft coupling is located within the interface and drives the input driveshaft of the external equipment in rotation, in the usual arrangement for any engine driven mechanism. The controller of the external equipment is configured to send control signals 32 to a controller of the ICE (such as an engine control unit, ECU), and to receive response signals 33 from the ECU indicating the operation condition of the engine. In this way, the external equipment 100, 200 is configured to operate the engine to drive the equipment as required to perform its various functions. The external equipment may be controlled from a control panel located on the external equipment, so that the power unit acts as a slave responsive to commands from the controller of the external equipment.

[0023] In the illustrated examples, the first external equipment 100 requires an electrical power supply from the power unit 1, in addition to shaft power, and so is connected to the power output connector 12 of the unit 1 via a power supply cable in use, as shown in Figs. 11 and 12. The second external equipment 200 requires only shaft power.

[0024] Of course, the external equipment could have any function, and could require only electrical power or only shaft power or both.

[0025] Referring again to Figs. 1 - 5, the power unit 1 includes a battery 10, which may be an Lithium-ion battery (such as used to power a vehicle) or any other battery technology. By battery is meant electrical energy storage, irrespective of the storage technology, which may be for example electrochemical or capacitive (supercapacitor) storage, or both.

[0026] The power unit 1 includes at least one power input connector 11, and at least one power output connector 12.

[0027] In the illustrated example there is a single power input connector 11, configured as a charging socket to which a charging cable may be connected. Other arrangement are possible, e g. multiple alternative power input connectors for charging from different power sources, and / or a permanently attached charging cable. A group of power output connectors 12 can be configured to provide different power formats such as single or three phase AC or DC at any voltage and current level as desired.

[0028] The unit also includes a battery charge control system 13, an output power control system 14, and a motor control system 30, which are illustrated schematically. Any or all of these control systems may include any or all of power electronics and switching arrangements, sensing arrangements, and control system logic embodied in software stored in non-transient memory and running on a processor. The control systems may be connected as separate units or combined together in any convenient arrangement, e.g. as different functional aspects of shared hardware.

[0029] The battery charge control system 13 is operable to charge the battery 10 with electrical power supplied from an external power source (not shown) via the power input connector 11. For example, the power source could be any type of charger (e.g. a fast charger) as used for charging electric vehicle batteries, or a single- or three-phase AC power supply.

[0030] The output power control system 14 is operable to supply electrical power from the battery 10 to the external equipment 100, 200 via the power output connector 12. It may include merely a simple fuse or circuit breaker or switch or switching arrangement, or may include one or more transformers or inverters or any other power supply management equipment as known in the art. By way of example, the output power control system 14 may include an inverter for converting DC power from the battery to AC power at any desired voltage. The power supply characteristics may be predefined or may be controllable by the user, e.g. via a control input means located on the unit 1, or via further control signals 32 through the control signal connector 31.

[0031] As best seen in Fig. 2, the unit 1 includes an output shaft 21 having an output shaft coupling 22 for connecting the output shaft 21 to the input shaft coupling 122 of the external equipment.

[0032] An electric motor 20 is powered by the battery 10 to drive the output shaft 21 in rotation about the output shaft axis X21. The motor 20 may be powered via an inverter 34 controlled by the motor control system 30. The motor may be connected directly to the output shaft 21 as shown, or may be connected via a transmission (not shown), e.g. a belt or gear driven transmission.

[0033] A control signal connector 31 is arranged to communicate control signals from the external equipment 100, 200 to the unit 1, and response signals from the unit 1 back to the external equipment. The control signals can control the motor 20 and may also control the electrical power supply via the power output connector(s) 12.

[0034] The control signal connector 31 may be arranged as a mechanical connector for a wired connection, such as an industry standard controller area network bus control system connector (as shown), or alternatively may be a wireless connector such as a transceiver (not shown).

[0035] The motor control system 30 is arranged to control operation of the electric motor 20 responsive to the control signals 32 received from the external equipment 100, 200 via the control signal connector 31.

[0036] A cooling fan 35 may be provided for cooling the power electronics and / or the battery.

[0037] As best seen in Fig. 2, the unit may include an output shaft mount 40 connectable in fixed relation to a body 101 of the external equipment 100, 200, wherein the output shaft 21 is rotatable about its axis X21 relative to the output shaft mount 40.

[0038] The output shaft mount 40 may define an array of output shaft mount fastener positions 41 surrounding an output shaft axis X21 of the output shaft 21. The array may be a circular array and may be coaxial with the output shaft axis X21.

[0039] The array of output shaft mount fastener positions 41 may correspond to a fastener position array of an SAE standard internal combustion engine flywheel housing.

[0040] For example, the mount may include an circular array of 8, 12 or 16 tapped fastener holes equally spaced around the shaft axis, with the array having a diameter from about 283mm to about 851mm, corresponding to an SAE no. 6, 5, 4, 3, 2, 1, 1 / 2, 0, or 00 ICE flywheel housing (often referred to as a bell housing).

[0041] In the illustrated example, the mount is configured in accordance with an SAE No. 3 engine flywheel housing.

[0042] The unit 1 may further include a chassis 50 (e g. a framework) supporting the battery 10 and the electric motor 20, the chassis 50 having chassis mounts 51 for fixing the chassis 50 to a support 300. The chassis mounts may be parts of a frame, as shown, or separate legs or struts (not shown).

[0043] As shown, the chassis mounts 51 may define a plurality of alternative chassis mount fastener positions 52 for fixing the chassis 50 to the support 300. In the illustrated example, the chassis mount fastener positions 52 are configured as holes formed in the chassis 50 for receiving bolts. Alternatively the chassis 50 could include adaptable or interchangeable brackets or feet (not shown) defining the chassis mount fastener positions 52, that can be configured as required to suit the support 300.

[0044] As illustrated, the output shaft mount 40 may define a circular array of output shaft mount fastener positions 41 surrounding the output shaft axis X21 of the output shaft 21, wherein the chassis mounts 51 define a plurality of chassis mount fastener positions 52 for fixing the chassis 50 to the support 300, the chassis mount fastener positions 52 being spaced apart in a chassis mount plane P51. In this arrangement, the output shaft mount fastener positions 41 may be spaced apart in an output shaft mount plane P40 perpendicular to the chassis mount plane P51. This makes it possible to mount the unit and the external equipment on a support 300 configured as a base frame or platform, with the external equipment connected to the output shaft mount 40, so that the support 300 helps to maintain the respective parts in fixed relation.

[0045] As illustrated in Figs. 13 and 14, this is particularly advantageous where the external equipment 200 is relatively large.

[0046] In such arrangements, as illustrated by the assembly of Figs. 13 and 14, the support 300 may be mounted on road wheels 60 for supporting the assembly on a road, and the assembly may include a towbar 61 for towing the assembly behind a vehicle (not shown). The chassis 50 may be fixed to the support 300 by chassis mount fasteners (such as bolts 53, Fig. 4) located at the chassis mount fastener positions 52. The support 300 extends beyond the power unit 1 to form a platform 301 for supporting the external equipment 200 when the external equipment 200 is connected to the output shaft mount 40.

[0047] In this configuration, the whole assembly can be towed periodically to a suitable charging location to recharge the battery 10.

[0048] Figs. 12 illustrates another possible arrangement, wherein the unit 1 includes road wheels 60 for supporting the power unit 1 on a road, and a towbar 61 for towing the power unit 1 behind a vehicle (not shown). Where the external equipment 100 is relatively compact, it may be mounted on the output shaft mount 40 without requiring a shared support frame 300, so that like the assembly of Fig. 14, the assembly of Fig. 12 can be towed to a charging location to recharge the battery 10 when required.

[0049] Fig. 11 illustrates another possible arrangement where the support 300 is configured as a skid supporting the unit 1 coupled to the external equipment 100. The assembly could be mounted for example on a vehicle that is parked onsite in use, and then driven to a charging location to recharge the battery 10 when required.

[0050] As shown in Figs. 11,12 and 14, the external equipment 100, 200 may be connected in use via a signal cable to the control signal connector 31 of the unit 1.

[0051] The motor control system 30 may be arranged to generate response signals 33, and to transmit the response signals 33 via the control signal connector 31, responsive to control signals 32 received from the external equipment 100, 200. The response signals 33 may be indicative of an operational condition of the electric motor 20, and may be configured to emulate response signals generated by a control system of an internal combustion engine in a corresponding said operational condition. [0052J The control signals 32 and response signals 33 may be standardised in accordance with a controller area network bus control system as commonly used in controlling internal combustion engines in vehicles, thus emulating the operational communications of an engine control unit (ECU).

[0053] That is to say, the signals 32, 33 may be in accordance with an industrial standard defining the signal format or protocol of a controller area network bus control system, e.g. a CAN (RTM) bus system.

[0054] By way of example, the signals 32, 33 may be in accordance with any or all of industrial standards ISO 11898-1:2015, ISO 11898-2:2016, ISO 11898-3:2006, ISO 11898-4:2004, ISO 11898-5:2007, and ISO 11898-6:2013.

[0055] In this way, a shaft powered external equipment 100, 200 configured for use with a conventional power unit having an ICE (internal combustion engine) may be connected to the novel power unit without any adaptation of its control system. The response signals 33 emulate the expected response of the ECU of an internal combustion engine reflecting the operational condition of the electric motor, and so corresponding to the control signal that would be produced by the ECU if the ICE were in a corresponding operational condition.

[0056] It will be appreciated of course that the operational conditions of the electric motor 10 will not necessarily have exact counterparts in the operational conditions of the ICE; thus, the response signals 33 are selected to indicate the most appropriate operational condition of the ICE corresponding to the momentary operational condition of the electric motor 10. Similarly, the motor control system 30 will respond to the control signals 32 as appropriate to reflect the operational requirements of the electric motor 10 which differ from those of the ICE.

[0057] By way of example, if the control signal 32 commands the motor controller 30 to energise glow plugs of a diesel engine, the motor controller may respond by generating a response signal 33 indicating that the engine is ready, but need not make any adjustment to the state of the electric motor, since the motor 10 is capable of producing power immediately on demand even when cold. If the control signal 32 demands more power, then the motor controller 30 may respond by supplying more power to the electric motor 10. Those skilled in the art will readily appreciate how the control output and response signals 33 of the motor controller, reflecting the actual operational condition of the electric motor 10, can be mapped appropriately onto the range of operational conditions of an ICE (whether fuelled for example by diesel or petrol) as commanded by the control signals 32, so as to provide the appropriate indication that allows the external equipment to exercise control over the motor 10 as if it were an ICE.

[0058] It should be understood that by response signals 33 is meant any signals produced by the motor control system 30, whether or not in response to control signals 32 from the external equipment. For example, the motor control sytsem 30 may generate an initial response signal 33 indicating that the motor control system 30 is available on the network.

[0059] The response signals 33 may also indicate for example fault conditions or alerts, such as low battery power alerts, which may prompt the external equipment 100, 200 to respond appropriately, e.g. by shutting down operation.

[0060] By way of example, the control signals 32 and response signals 33 may include any or all of the examples set out in the following table (which is to say, the signals 32, 33 may correspond to one or more lines of the table.)

[0061] Example signal configurations Control signal 32 Commanded Response signal 33 Actual operational (from external operational (from motor condition of electric equipment) condition of ICE controller) motor 10 Key switch - on Power up Wait to start (glowplug light) Wait to start Insulation resistance checks Crank command Engine starts Speed feedback signal = 120rpm Precharge inverters, Close contactors, motor = Orpm Key Switch - Off Power down, open contactors Desired RPM = idle Speed feedback signal = idle Speed = Orpm Contactors still closed. 12 / 24V voltage output charging battery Oil P check Oil P = good when contactors closed Throttle - operation Speed = 1000-2200 Speed = 1000-2200 Engine Warning Indicator Illuminate on warning fault with electrical system Derate Emissions System Failure Indicator (also known as MIL) Always OK Engine Coolant Temp Gauge Use motor / inverter coolant temperature signal Torque limit Limit the engine output torque Limit the motor output torque

[0062] Preferably the power unit 1 does not include an internal combustion engine. All of the power that is supplied to the external equipment 100, 200 may be stored in, and supplied from the battery 10, whether as electrical power via the power output connector 12 or as shaft power via the output shaft 21. Advantageously, the battery 10 may supply a higher power than flows during recharging, so that it can be used to supply external equipment with a high but intermittent power demand.

[0063] Referring now to Fig. 6, a method of supplying power to external equipment 100, 200 includes providing the power unit 1 (step 1); connecting the output shaft 21 via the output shaft coupling 22 to an input shaft coupling 122 of the external equipment (step 2); and connecting the motor control system 30 via the control signal connector 31 to the external equipment (step 3). The method further includes controlling operation of the electric motor 20, by the motor control system 30, to drive an input shaft 121 of the external equipment in rotation, responsive to control signals 32 received from the external equipment via the control signal connector 31 (step 4). Industrial Applicability

[0064] The novel power unit can be used to supply either or both of shaft power and electrical power to any external equipment to which it is connected, without the emissions associated with conventional power units driven by internal combustion engines.

[0065] Advantageously, by emulating the control system of an internal combustion engine, the novel power unit can be connected to shaft driven external equipment as a direct replacement for a conventional internal combustion engine power unit, without reconfiguring the control system of the external equipment.

[0066] By arranging the shaft mount to correspond to an SAE standard internal combustion engine flywheel housing, a shaft driven external equipment designed for connection to a flywheel housing of an internal combustion engine can be connected directly to the novel power unit without further adaptation.

[0067] By providing chassis mounts in combination with the output shaft mount, and preferably also arranging the output shaft mount plane perpendicular to the chassis mount plane, both the novel power unit and the external equipment can be mounted on a fixed horizontal support or bed 300 and coupled together at the output shaft mount 40 to provide a single assembly, which can then be shipped to the end user for operation in a convenient format. For example, the fixed bed could be arranged as a skid chassis (e.g. as shown in Fig. 11) or a wheeled chassis (e.g. as shown in Figs. 13 and 14), or as the floor of a container (e.g. a multimodal ISO shipping container) (not shown) for containerised applications.

[0068] In summary, a power unit for supplying power to a variety of interchangeable external equipment includes a battery for storing the power, electrical input and output connectors and control systems for charging the battery and supplying electrical power from the battery to the external equipment, and an output shaft driven by a motor powered by the battery for supplying shaft power to the external equipment. A motor control system 30 controls operation of the motor 20 responsive to control signals 32 received from the external equipment via a control signal connector 31. The control system may emulate the controller of an internal combustion engine, and the power unit may include an output shaft mount corresponding to an SAE standard flywheel housing, so that the power unit may be used as a direct replacement for a conventional power unit having an internal combustion engine.

[0069] The skilled person will appreciate that many other types of external equipment may be driven by the power unit, which can supply either or both of shaft power and electrical power as may be required, and irrespective of the function of the external equipment.

[0070] The novel power unit may be used for both static and mobile applications, and may differ from the illustrated example, e.g. in its shape or dimensions or other characteristics.

[0071] The novel power unit may be configured to provide any desired amount of electrical power, for example, from about lOkW up to 250kW or more.

[0072] The unit could include two or more motors controlled as described above, each driving a respective output shaft 21 and output shaft coupling 22 and preferably having a respective output shaft mount 40 as described above, so as to supply shaft power to more than one input shaft of the external equipment (or to more than one shaft driven external equipment.)

[0073] A cooling system including for example a liquid coolant may be provided for cooling the power electronics or other components of the unit 1.

[0074] Many further adaptations are possible within the scope of the claims.

[0075] In the claims, reference numerals and characters are provided in parentheses, purely for ease of reference, and should not be construed as limiting features. LIST OF ELEMENTS TITLE: Battery operated power unit and method for supplying power to external equipment FILE: 24-0782GB01 1 Power unit 10 Battery 11 Power input connector 12 Power output connector 13 Battery charge control system 14 Output power control system 20 Electric motor 21 Output shaft 22 Output shaft coupling 30 Motor control system 31 Control signal connector 32 Control signals 33 Response signals 34 Inverter 35 Cooling fan 40 Output shaft mount 41 Output shaft mount fastener position 50 Chassis 51 Chassis mount 52 Chassis mount fastener position 53 Chassis mount fastener 60 Road wheels 61 Towbar 100 First external equipment 101 Body of external equipment 121 Input shaft of external equipment 122 Input shaft coupling 200 Second external equipment 300 Support 301 Platform P40 Output shaft mount plane P51 Chassis mount plane X21 Output shaft axis

Claims

What is claimed is:

1. A power unit (1), being interchangeably connectable to a variety of different external equipment (100, 200) to supply power to the external equipment (100, 200);the power unit (1) including:a battery (10);at least one power input connector (11);at least one power output connector (12);a battery charge control system (13) for charging the battery (10) with electrical power supplied from an external power source via the power input connector (11);an output power control system (14) for supplying electrical power from the battery (10) to the external equipment (100, 200) via the power output connector (12);and further including:at least one output shaft (21) having an output shaft coupling (22) for connecting the output shaft (21) to an input shaft coupling (122) of the external equipment (100, 200);at least one electric motor (20) powered by the battery (10) for driving the at least one output shaft (21) in rotation;a control signal connector (31); anda motor control system (30) for controlling operation of the electric motor (20) responsive to control signals (32) received from the external equipment via the control signal connector (31).

2. A power unit (1) according to claim 1, further including an output shaft mount (40) connectable in fixed relation to a body (101) of the external equipment (100, 200);the output shaft (21) being rotatable relative to the output shaft mount (40).

3. A power unit (1) according to claim 2, wherein the output shaft mount (40) defines an array of output shaft mount fastener positions (41) surrounding an output shaft axis (X21) of the output shaft (21).

4. A power unit (1) according to claim 3, wherein the array of output shaft mount fastener positions (41) corresponds to a fastener position array of an SAE standard internal combustion engine flywheel housing.

5. A power unit (1) according to claim 2, further including a chassis (50) supporting the battery (10) and the electric motor (20), the chassis (50) having chassis mounts (51) for fixing the chassis (50) to a support (300).

6. A power unit (1) according to claim 5, wherein the output shaft mount (40) defines a circular array of output shaft mount fastener positions (41) surrounding an output shaft axis (X21) of the output shaft (21); andthe chassis mounts (51) define a plurality of chassis mount fastener positions (52) for fixing the chassis (50) to the support (300), the chassis mount fastener positions (52) being spaced apart in a chassis mount plane (P51); andthe output shaft mount fastener positions (41) are spaced apart in an output shaft mount plane (P40) perpendicular to the chassis mount plane (P51).

7. An assembly including:the power unit (1) according to claim 6;a support (300) mounted on road wheels (60) for supporting the assembly on a road; anda towbar (61) for towing the assembly behind a vehicle;the chassis (50) being fixed to the support (300) by chassis mount fasteners (53) at said chassis mount fastener positions (52);the support (300) extending beyond the power unit to form a platform (301) for supporting the external equipment (200) when the external equipment (200) is connected to the output shaft mount (40).

8. A power unit (1) according to claim 2, further including road wheels (60) for supporting the power unit on a road, and a towbar (61) for towing the power unit (1) behind a vehicle.

9. A power unit (1) according to claim 1, wherein the motor control system (30) is arranged to generate response signals (33), and to transmit the response signals (33) via the control signal connector (31), responsive to said control signals (32) received from the external equipment (100, 200);said response signals (33) being indicative of an operational condition of the electric motor (20), and configured to emulate response signals generated by a control system of an internal combustion engine in a corresponding said operational condition.

10. A power unit (1) according to claim 9, wherein said control signals (32) and said response signals (33) are standardised in accordance with a controller area network bus control system.

11. A power unit (1) according to claim 1, wherein the power unit (1) is arranged to supply all of said power to the external equipment (100, 200) from the battery (10), as electrical power via the power output connector (12) or as shaft power via the output shaft (21).

12. A power unit (1) according to claim 1, wherein the power unit (1) does not include an internal combustion engine.

13. A method of supplying power to external equipment (100, 200), including:(SI) providing a power unit (1) according to claim 1;(S2) connecting the output shaft (21) via the output shaft coupling (22) to an input shaft coupling (122) of the external equipment (100, 200);(S3) connecting the motor control system (30) via the control signal connector (31) to the external equipment (100, 200); and(S4) controlling operation of the electric motor (20), by the motor control system (30), to drive an input shaft (121) of the external equipment (100, 200) in rotation, responsive to control signals (32) received from the external equipment (100, 200) via the control signal connector (31).

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