Method for connecting auxiliary electrical system to electrical network of vehicle

Abstract

A method (400) for connecting an auxiliary electrical system (300a, 300b) with an electrical power network (200) of a vehicle (100), the method comprising: i) the auxiliary electrical system sending an activation request to the electrical power network of the vehicle; ii) a power network of the vehicle, electrically coupling a battery (210) of the power network of the vehicle to a power output point (230) of the vehicle in response to an activation request sent by the auxiliary electrical system, and providing an indication to the auxiliary electrical system that the power output device has been activated; iii) an auxiliary electrical system, in response to an indication that the power output device has been enabled: pre-charging (416) a DC bus of the auxiliary electrical system, and closing a contactor (312) of the auxiliary electrical system to electrically couple the auxiliary electrical system to a power output point of the vehicle.

Description

Technical Field

[0001] The present disclosure relates to a method for connecting an auxiliary electrical system to an electrical power network of a vehicle. The present disclosure also extends to an auxiliary electrical system and a transport refrigeration unit comprising the auxiliary electrical system, and an electrical power network for a vehicle and a vehicle comprising the electrical power network. Background Art

[0002] It is known to connect an auxiliary electrical system, such as the electrical system of a transport refrigeration unit (TRU), to an electrical power take-off (ePTO) point of a vehicle in order to draw power from the vehicle's electrical network (i.e., the vehicle power network). The vehicle power network may typically include an electrical energy storage system (e.g., a battery) for providing power to various components of the vehicle, such as drive motors coupled to the vehicle's wheels. When connected to the ePTO point, the auxiliary electrical system may receive power from the vehicle battery. For example, where the auxiliary electrical system is the electrical system of the TRU, power drawn by the auxiliary system from the vehicle power network (via the ePTO point) may be used to operate various components of the TRU, such as a compressor, and / or a fan, that forms part of a vapor compression circuit of the TRU.

[0003] In known systems, the vehicle power network may include a contactor for selectively preventing and allowing power to flow to the ePTO point. When the vehicle power network is able to supply power to the ePTO point (e.g., when the battery's state of charge is sufficiently high and / or when the vehicle power network can meet the power demand imposed on the vehicle power network), the contactor may be closed and the auxiliary electrical system may then draw power from the vehicle power network accordingly.

[0004] In such known systems, there is no coordination between the vehicle and the auxiliary electrical system. When the contactors are closed, electricity can flow from the ePTO point. Therefore, during installation of the auxiliary electrical system, when the contactors of the vehicle power network are closed, there is a risk that a high inrush current may flow into the auxiliary electrical system, which may damage the auxiliary electrical system. Furthermore, in the known system, an operator needs to manually connect the auxiliary electrical system to the ePTO point of the vehicle. If the contactors of the vehicle power network are closed before making such a manual connection, there is a risk of electric shock to the operator when making such a connection.

[0005] Therefore, it is desirable to improve the way of making electrical connections between a vehicle power network and an auxiliary electrical system. The present disclosure is designed in view of the above circumstances. Summary of the invention

[0006] According to a first aspect, the present invention provides a method for connecting an auxiliary electrical system to an electrical network of a vehicle, the method comprising: i) the auxiliary electrical system sending an engagement request to the electrical network of the vehicle; ii) in response to the engagement request sent by the auxiliary electrical system, the electrical network of the vehicle electrically couples a battery of the electrical network of the vehicle to an electrical power output point of the vehicle and provides an indication to the auxiliary electrical system that an electrical power take-off has been enabled; iii) the auxiliary electrical system, in response to the indication that the electrical power take-off has been enabled: pre-charging a DC bus of the auxiliary electrical system; and closing contactors of the auxiliary electrical system to electrically couple the auxiliary electrical system to the electrical power output point of the vehicle.

[0007] The method may further comprise the auxiliary electrical system determining that there is a demand for electrical power from the electrical power network of the vehicle before sending the enablement request to the electrical power network of the vehicle.

[0008] The method may further comprise pre-charging the power output device by the power network prior to providing an indication to the auxiliary electrical system that the power output device is enabled.

[0009] Providing an indication that the power output device is enabled may include one or more of: setting an internal state of the power network to enabled; and sending an enable response to the auxiliary electrical system indicating that the power output device is enabled.

[0010] The method may further include the auxiliary electrical system detecting a voltage at the power output point before precharging the DC bus.

[0011] Detecting the voltage at the power output point may include one or more of: receiving an indication of the voltage at the power output point from the vehicle power network; and the auxiliary electrical system monitoring the voltage at the power output point.

[0012] The auxiliary electrical system may pre-charge the DC bus by either: using a pre-charging circuit of the auxiliary electrical system, wherein the pre-charging circuit draws power from a battery; or by the auxiliary electrical system drawing current from the power output point through a resistor.

[0013] When the auxiliary electrical system draws current from the power output point through a resistor to pre-charge the DC bus, the auxiliary electrical system closes its contactor before pre-charging the DC bus.

[0014] When the DC bus is precharged using the precharging circuit of the auxiliary electric system, the auxiliary electric system closes its contactor after precharging the DC bus.

[0015] When the voltage of the DC bus is within a predetermined threshold of the voltage at the power output point, the contactors of the auxiliary electrical system may be closed.

[0016] Communication between the auxiliary electrical system and the power grid can be carried out via the Controller Area Network bus.

[0017] The method may further include the auxiliary electrical system determining that power is no longer required from the vehicle power network.

[0018] The method may further comprise the auxiliary electrical system sending a disengagement request to an electrical network of the vehicle.

[0019] The method may further include assisting the electrical system in performing a discharge process to discharge the DC bus.

[0020] The method may further include electrically decoupling the vehicle battery from the power output point in response to the deactivation request, via the vehicle's power network.

[0021] The method may further include the power network of the vehicle performing a discharge process to discharge the power output point.

[0022] The method may further include the auxiliary electrical system opening a contactor thereof in response to detecting a voltage drop at the power output point.

[0023] The method may further include assisting the electrical system in performing a discharge process to discharge the DC bus.

[0024] According to a second aspect, the present invention provides an auxiliary electrical system configured to be connected to a power network of a vehicle, the auxiliary electrical system comprising: a connector configured to be coupled to the power network of the vehicle; a power distribution unit; contactor, and a DC bus, wherein the auxiliary electrical system is configured to: send an enable request to the power network of the vehicle; and in response to an indication provided by the power network of the vehicle that the power output device of the power network of the vehicle is enabled: pre-charge the DC bus; and close the contactor to electrically couple the auxiliary electrical system to the power output point of the power network of the vehicle.

[0025] According to a third aspect, the present invention provides a vehicle power network configured to be connected to an auxiliary electrical system, the vehicle power network comprising: a battery; a power output point, the power output point being configured to be electrically coupled to the auxiliary electrical system; and a contactor, the contactor being used to selectively couple the battery to the power output point, wherein the vehicle power network is configured to respond to an enablement request sent by the auxiliary electrical system: electrically couple the battery to the power output point; and provide an indication to the auxiliary electrical system that the power output device has been enabled.

[0026] According to a fourth aspect, the present invention provides a method performed by an auxiliary electrical system for connecting an auxiliary electrical system to a power network of a vehicle, the method comprising: sending an activation request to the power network of the vehicle; and in response to an indication provided by the power network of the vehicle that a power output device of the power network of the vehicle is activated: precharging a DC bus of the auxiliary electrical system; and closing a contactor of the auxiliary electrical system to electrically couple the auxiliary electrical system to a power output point of the vehicle.

[0027] According to a fifth aspect, the invention provides a method for connecting an auxiliary electrical system to a vehicle's electrical network, the method comprising: in response to an activation request sent by the auxiliary electrical system: A battery of the power network of the vehicle is electrically coupled to a power take-off point of the vehicle and an indication is provided to the auxiliary electrical system that a power take-off device is enabled.

[0028] According to a sixth aspect, the present invention provides a computer program comprising instructions for causing the auxiliary electrical system of the second aspect to perform the method of the fourth aspect.

[0029] According to a seventh aspect, the present invention provides a computer program comprising instructions for causing the vehicle power network of the third aspect to perform the method of the fifth aspect.

[0030] According to an eighth aspect, the present invention provides a computer-readable medium on which the computer program of the sixth aspect or the seventh aspect is stored.

[0031] According to a ninth aspect, the present invention provides a transport refrigeration unit comprising the auxiliary electrical system of the second aspect and one or more of: a compressor and a fan.

[0032] According to a tenth aspect, the invention provides a vehicle comprising the vehicle power network of the third aspect.

[0033] In this specification, the word "comprise" or variations such as "includes" or "comprising" will be understood to imply the inclusion of a stated element, integer or step, or a group of elements, integers and steps, but not the exclusion of any other element, integer or step, or a group of elements, integers or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Embodiments of the present disclosure will now be described strictly by way of example only, with reference to the accompanying drawings, in which:

[0035] Figure 1 A vehicle including a transport refrigeration system is shown;

[0036] Figure 2 is a schematic diagram showing the power network and auxiliary electrical systems of the vehicle;

[0037] Figure 3 is a schematic diagram showing the vehicle's electrical network and alternative auxiliary electrical systems;

[0038] Figure 4A is a flow chart illustrating steps in a method for connecting an auxiliary electrical system to an electrical power network of a vehicle;

[0039] Figure 4B is a flow chart illustrating further steps in a method for connecting an auxiliary electrical system to an electrical power network of a vehicle;

[0040] Figure 4C is a flow chart illustrating further steps in a method for connecting an auxiliary electrical system to an electrical power network of a vehicle; and

[0041] Figure 5 A machine-readable medium storing computer programs which, when executed by appropriate processing devices of the vehicle's power network and auxiliary electrical systems, cause the power network and auxiliary electrical systems to perform Figures 4A-4C The method shown in . DETAILED DESCRIPTION

[0042] Figure 1 A vehicle 100 is shown including a transport refrigeration system 110. Figure 1 In the example of FIG. 1 , a transport refrigeration system 110 forms part of an on-road refrigerated semi-trailer having a structure 130 supporting (or forming) at least one climate-controlled compartment 140 that is configured to be cooled and / or heated by a TRU 150. The climate-controlled compartment 140 may take the form of multiple compartments or have multiple zones. The structure 130 includes a chassis. The structure 130 supports the TRU 150. The vehicle 100 also includes a tractor unit 160 that can be removably coupled to the trailer.

[0043] Figure 2is a schematic diagram showing a power network of a vehicle (also referred to herein as a vehicle power network) and auxiliary electrical systems according to the present disclosure.

[0044] Figure 2 The vehicle power network denoted by 200 may be incorporated into or installed in a vehicle (eg Figure 1 ), in the example shown, the vehicle power network includes a battery 210 , a battery management system (BMS) 220 , and a connector 230 .

[0045] The battery 210 may be a high voltage battery having a nominal or rated voltage of, for example, 400 V DC or 800 V DC The battery 210 is coupled to a battery management system 220 .

[0046] The connector 230 is configured to allow the vehicle power network 200 to be coupled to the auxiliary electrical system 300a, for example via a suitable cable. Thus, the connector 230 provides a power take-off (ePTO) point (also referred to simply as a power take-off or ePTO) for the vehicle power network 200 .

[0047] The battery management system 220 is configured to receive a power supply voltage from the battery 210 and provide an output voltage to the connector 230. In the example shown, the battery management system 220 includes a contactor 222 for selectively allowing or preventing current from flowing from the battery 210 to the connector 230. Thus, when the contactor 222 is closed, current can flow from the battery 210 to the connector 230, and when the contactor 222 is open, current cannot flow from the battery 210 to the connector 230. It will be appreciated by those of ordinary skill in the art that the contactor 222 need not be included in the battery management system 220, but may instead be disposed elsewhere in the vehicle power network 200. For example, the contactor 222 may be coupled between the output of the battery management system 220 and the connector 230.

[0048] The auxiliary electrical system 300 a in this example includes a power distribution unit (PDU) 310 a , a core power module (CPM) having a DC link module 320 and a pre-charging circuit 330 , and a connector 340 .

[0049] The power distribution unit 310 a is configured to receive power from the vehicle power network 200 (eg, via a suitable cable coupled between the connector 230 of the vehicle power network 100 and the connector 340 of the auxiliary electrical system 300 a ) and distribute it to the DC link module 320 .

[0050] In the illustrated example, the power distribution unit 310a includes a contactor 312 for selectively allowing or preventing current from flowing from the power distribution unit 310a to the DC link module 320. Thus, when the contactor 312 is closed, current can flow from the power distribution unit 310a to the DC link module 320, and when the contactor 312 is open, current cannot flow from the power distribution unit 310a to the DC link module 320. It will be appreciated by those of ordinary skill in the art that the contactor 312 need not be included in the power distribution unit 310a, but may instead be disposed elsewhere in the auxiliary electrical system 300a. For example, the contactor 312 may be coupled between the connector 340 and the input of the power distribution unit 310a, or between the output of the power distribution unit 310a and the DC link module 320.

[0051] The DC link module 320 is configured to receive DC power from the power distribution unit 310a and provide DC power to downstream components or subsystems of the host system (e.g., if the host system is a TRU, a compressor, a fan, etc.). The DC link module 320 may include one or more power converters for converting an input DC voltage of a first amplitude received from the power distribution unit 310a into one or more output DC or AC voltages of an amplitude different from the first amplitude for powering the components or subsystems of the host system.

[0052] The DC link module 320 in this example includes a DC bus 322 having capacitors 324 for smoothing and filtering the DC input voltage received from the power distribution unit 310a, for example, to reduce ripple introduced by any switching power converters that receive the DC input voltage from the DC bus 322. Those of ordinary skill in the art will appreciate that the DC bus 322 and associated DC capacitors 324 need not be incorporated into the DC link module 320, but may instead be provided elsewhere in the auxiliary electrical system 300a.

[0053] To prevent potentially damaging inrush current from flowing into the DC link module 32 (and into any power converters forming part of or coupled to the DC link module 330) when the contactor 312 is first closed to provide a DC voltage to the DC link module 320, the DC bus 322 should be precharged (e.g., by precharging the capacitor 324) before the contactor 312 is closed. The precharge circuit 330 is configured to perform such precharging.

[0054] exist Figure 2In the example shown, the pre-charge circuit 330 is powered by a low voltage battery 332 (e.g., a battery having a nominal or rated output voltage of 12 volts DC) and a DC-DC converter 334. The low voltage battery 332 may be, for example, a low voltage battery of the vehicle 100. The DC-DC converter 334 is configured to convert a relatively low (e.g., 12V) DC voltage to a relatively high (e.g., 400V) DC voltage and provide the relatively high DC voltage to the DC bus 322 to pre-charge the capacitor 324 to a voltage equal to or at least within a pre-defined threshold of the DC voltage magnitude provided by the power distribution unit 310a when the contactor 312 is closed. Pre-charging the capacitor 324 (and therefore the DC bus 322) in this manner reduces the amount of current that can flow into the DC link module 320 when the contactor 312 is first closed.

[0055] Figure 3 is a schematic diagram illustrating a vehicle's electrical power network (also referred to herein as a vehicle electrical power network) and an alternative auxiliary electrical system in accordance with the present disclosure.

[0056] Figure 3 Power grid and alternative auxiliary electrical systems and Figure 2 The power grid and auxiliary electrical systems of Figure 2 and Figure 3 The components are denoted by common reference numerals and will not be described in detail here for the sake of clarity and conciseness.

[0057] Figure 3 The alternative auxiliary electrical system shown in 300b is usually used with Figure 2 The auxiliary electrical system 300 a differs in that it does not include a pre-charge circuit 330 .

[0058] Alternatively, the power distribution unit 310b of the alternative auxiliary electrical system 300b includes an additional pre-charging circuit including a switch or contactor 314 and a resistor 316 coupled in series between an input of the power distribution unit 310b and an output of the power distribution unit 310b. The additional pre-charging circuit enables the DC bus 322 to be pre-charged using current received from the vehicle power network 200 before the contactor 312 is closed.

[0059] When the switch or contactor 314 is closed, current can flow from the vehicle power network 200 (e.g., through a suitable cable coupled between the connector 230 of the vehicle power network 200 and the connector 340 of the auxiliary electrical system 300b) to the DC bus 322, and thus to the capacitor 324, to charge the capacitor 324 and thereby the DC bus 322. The series resistor 316 limits the amount of current that can flow during the pre-charging of the DC bus 322. As in Figure 2 In the example shown, contactor 312 can be closed once capacitor 324 is pre-charged to a voltage equal to a predefined threshold of the amplitude of the DC voltage provided by distribution unit 310a when contactor 312 is closed, or at least a voltage within a predefined threshold of the amplitude of the DC voltage provided by distribution unit 310a when contactor 312 is closed.

[0060] Figure 4A is a diagram for connecting auxiliary electrical systems (e.g. Figure 2 Auxiliary electrical system 300a or Figure 3 The auxiliary power system 300b) is connected to the vehicle power network (eg, Figure 2 and Figure 3 Flow chart of the steps in a method 400 of connecting a vehicle power network 200 ).

[0061] If the vehicle power network 200 can supply power to the auxiliary electrical systems 300a, 300b, the ePTO of the vehicle power network 100 can be activated (enabled). In some examples (e.g., where there is a permanent electrical coupling between the battery 210 and the battery management system 220), the ePTO can be always activated, or can be automatically activated when the vehicle's electrical system is activated (e.g., when the vehicle electrical system is turned on by turning the ignition key, pressing a switch, etc.). In other examples, the ePTO can be manually activated, such as by activating a switch on the vehicle dashboard or remotely activated through an application, etc. Activating the ePTO in this manner can activate the electrical connection between the battery 210 and the battery management system 220, for example, by closing a switch or contactor in the coupling between the battery 210 and the battery management system 220.

[0062] When the ePTO is activated, the vehicle power network 200 may set the internal state to be enabled by the ePTO. When the ePTO is not activated (or disabled), the vehicle power network 200 may set the internal state to be unavailable for activation.

[0063] In response to the auxiliary electrical system 300a, 300b determining that there is a demand for power from the vehicle power network 200 ( Figure 4AIn step 402, the auxiliary electrical system 300a, 300b communicates with the vehicle power network 200 to check the status of the ePTO of the vehicle power network 200 (step 404). For example, in order to check the status of the ePTO, the auxiliary electrical system 300a, 300b can query the internal status of the vehicle power network 200.

[0064] If the status check of the ePTO indicates that the ePTO of the vehicle power network 200 is ready for activation with the auxiliary electrical system 300a, 300b, the auxiliary electrical system 300a, 300b sends an activation request to the vehicle power network 100 (step 406).

[0065] In response to the enablement request, the vehicle power network 200 may pre-charge the ePTO, such as by charging a capacitor of or associated with the battery management system 220 (step 408), and couple the ePTO to the vehicle battery 210, such as by closing the contactor 222 to electrically couple the connector 230 of the vehicle power network 200 to the battery 210 (step 410).

[0066] Once the voltage at the ePTO of the vehicle power network 200 (e.g., the voltage across a capacitor of or associated with the battery management system 220) is equal to the voltage of the battery 210 (or at least within some predefined threshold of the voltage of the battery 210), the vehicle power network 220 sets its internal state to be ready for activation with the auxiliary electrical systems 300a, 300b (step 412). Additionally or alternatively, the vehicle power network 200 may send an activation response to the auxiliary electrical systems 300a, 300b indicating that the vehicle power network 200 is ready for activation with the auxiliary electrical systems 300a, 300b.

[0067] The auxiliary electrical system 300a, 300b may detect (at step 414) the voltage of the ePTO of the vehicle power network 200. In some examples, the vehicle power network 200 may send an indication of the voltage of the ePTO to the auxiliary electrical system 300a, 300b (e.g., periodically or continuously). In other examples, the auxiliary electrical system 300a, 300b may use an appropriate sensing device to monitor the voltage at the ePTO.

[0068] In response to the internal state of the vehicle power network 200 changing to ready to enable and / or an enable response message, the auxiliary electrical system 300a, 300b begins (at step 416) a pre-charge routine to pre-charge the DC bus 322 to a voltage equal to or close to the ePTO voltage.

[0069] In the auxiliary electrical system 300a, as described above with reference to Figure 2As described, pre-charging is performed using the pre-charging circuit 330 to pre-charge the DC bus 322 from the battery 332 of the auxiliary electrical system 300 a.

[0070] In the alternative auxiliary electrical system 300b, as shown in FIG. Figure 3 As described, pre-charging is performed using the pre-charging circuit (switch or contactor 314 and resistor 316) of the power distribution unit 310b to pre-charge the DC bus 322 from the vehicle power network 200. In order to allow the pre-charging current to flow from the vehicle power network 200 (via resistor 316) to the DC bus 322, at step 420b, the alternative auxiliary electrical system 300b is operable to close its contactor 312 before commencing the pre-charging routine. Thus, when the alternative auxiliary electrical system 300b is connected to the vehicle power network 200, step 420b of the method 400 is performed before step 416. The resistor 316 limits the current that can flow into the DC bus 322, thereby preventing potentially destructive inrush currents.

[0071] Once the voltage of the DC bus 322 (e.g., the voltage across the capacitor 324) reaches a voltage equal to or at least within a predefined threshold of the voltage of the ePTO of the vehicle power network 200 (step 418), the auxiliary electrical systems 300a, 300b close their contactors 312 (step 420a) to allow current to flow from the vehicle power network 200 to the DC link modules 320 of the auxiliary electrical systems 300a, 300b.

[0072] Figure 4B is a flow chart illustrating further steps in the method 400 which may be performed if the auxiliary electrical system 300a, 300b determines that power from the vehicle power network 200 is no longer required.

[0073] At step 422, the auxiliary electrical system 300a, 300b determines that power is no longer needed from the vehicle power network 200. The auxiliary electrical system 300a, 300b may then perform a discharge process to reduce the voltage on its DC bus 322 to zero (step 424). The auxiliary electrical system 300a, 300b may also send a deactivation request to the vehicle power network 200 (step 426). In response to the deactivation request, the vehicle power network 200 may perform its own discharge process (step 428), such as by opening the contactor 222, to reduce the voltage at the ePTO before decoupling the vehicle battery 210 from the ePTO (step 430).

[0074] Figure 4Cis a flow chart illustrating further steps in method 400 that may be performed if the vehicle power network 200 unilaterally deactivates the ePTO, such as by opening contactor 222. This may occur, for example, if the state of charge of the vehicle battery 210 drops below a predefined minimum level (e.g., a minimum level at which the vehicle battery 210 can safely or reliably power the vehicle and auxiliary electrical systems 300a, 300b).

[0075] When the vehicle power network 200 deactivates the ePTO (step 432), the ePTO voltage rapidly begins to drop to zero (step 434). It should be recalled that the auxiliary electrical system 300a, 300b detects the ePTO, for example using an appropriate sensing device or based on an indication of the ePTO voltage sent by the vehicle power network 200. At step 436, the auxiliary electrical system 300a, 300b detects the voltage drop due to the deactivation of the ePTO (e.g., this can be distinguished from normal fluctuations in the ePTO voltage by the auxiliary electrical system 300a, 300b based on the rate of change of the ePTO voltage or the magnitude of the ePTO voltage drop). In response, the auxiliary electrical system 300a, 300b opens its contactor 312 (step 438), and can then perform a discharge process to reduce the voltage on its DC bus to zero (step 440).

[0076] exist Figures 4A-4C In the illustrated method 400, communication between the vehicle power network 200 and the auxiliary electrical systems 300a, 300b (e.g., sending enable requests and disable requests from the auxiliary electrical systems 300a, 300b to the vehicle power network 200, and sending enable responses and indications of ePTO voltage from the vehicle power network 200 to the auxiliary electrical systems 400a, 300b) can be performed via a controller area network (CAN) bus, with the vehicle power network 200 and the auxiliary electrical systems 300a, 300a each being provided with a suitable CAN node and CAN transceiver, as is well known to those skilled in the art.

[0077] Thus, the method 400 provides a handshake protocol or signal exchange protocol for connecting the auxiliary electrical system 300a, 300b to the vehicle power network 200 in a manner that ensures that pre-charging of the DC bus 324 is properly performed, thereby reducing the risk of potentially damaging inrush current to the auxiliary electrical system 300a, 300b. In addition, the handshake protocol improves operator safety.

[0078] No current can flow from the vehicle power network 200 until at least steps 404, 410-412, and 416-420a / 420b of method 400 are completed. Therefore, when an operator manually connects the auxiliary electrical system 300a, 300b to the vehicle's ePTO, no current can flow from the ePTO, thereby reducing the risk of electric shock to the operator.

[0079] When the auxiliary electrical systems 300a, 300b no longer need to receive power from the vehicle power network 200, or when the vehicle power network unilaterally deactivates the ePTO, an additional step of discharging the DC bus of the auxiliary electrical systems 300a, 300b can be performed, which further improves operator safety because no residual electrical energy is stored in the auxiliary electrical systems 300a, 300a after the auxiliary electrical systems 300a, 300b stop receiving power from the vehicle power network 200.

[0080] Similarly, when the auxiliary electrical systems 300a, 300b are no longer required to receive power from the vehicle power network 200, an additional step of discharging the ePTO can be performed, which further improves operator safety because the ePTO contains no residual power after stopping powering the auxiliary electrical systems 300a, 300b.

[0081] The method 400 may be implemented in software (i.e., one or more computer programs) that is executed by appropriate processing devices (e.g., microprocessors, microprocessors, etc.) of the vehicle power network 200 and the auxiliary electrical systems 300a, 300b. It should be understood that the first computer program will be executed by the processing device of the auxiliary electrical systems 300a, 300b to perform those steps of the method 400 performed by the auxiliary electrical systems 300a, 300a (which may be regarded as constituting a first method performed by the auxiliary electrical systems 300a, 300b), and the second computer program will be run by the processing device of the vehicle power network 200 to perform those steps of the method 400 performed by the vehicle power network 200 (which may be regarded as constituting a second method performed by the vehicle power network 200).

[0082] Figure 5A first machine-readable medium 500 and a second machine-readable medium 550 are shown highly schematically, on which a first computer program 510 is stored, which first computer program 510 contains instructions, which when executed by a suitable processing device 520 of the auxiliary electrical system 300a, 300b, cause the auxiliary electrical system 300a, 300b to perform the steps of the above-mentioned first method, and on which a second computer-readable medium 550 a second computer program 560 is stored, which second computer program 560 contains instructions, which when executed by a suitable processing device 570 of the vehicle power network 200, cause the vehicle power network 200 to perform the steps of the above-mentioned second method.

[0083] Unless mutually exclusive, features described in connection with any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore, unless mutually exclusive, any feature described herein may be applied to any aspect and / or combined with any other feature described herein. Furthermore, while the present disclosure is made in the context of transport refrigeration systems and / or vapor compression circuits, it should be understood that the present disclosure has other possible applications in other technical fields.

[0084] The present disclosure covers all changes, substitutions, changes, alterations and modifications to the exemplary embodiments herein that will be understood by a person of ordinary skill in the art. Similarly, where appropriate, the attached claims cover all changes, substitutions, changes, alterations and modifications to the exemplary embodiments herein that will be understood by a person of ordinary skill in the art. In addition, in the attached claims, references to a device or system or a component of a device or system that is suitable for, arranged to, capable of, configured to, activated to, capable of being operated to or operable to perform a specific function cover the device, system or component, regardless of whether it or its specific function is actuated, opened or unlocked, as long as the device, system or component is so adapted, arranged, capable of, configured to, activated to, capable of being operated or operable. Therefore, without departing from the scope of the present disclosure, the systems, devices and methods described herein may be modified, added or omitted. For example, the components of the systems and devices may be integrated or separated. In addition, the operations of the systems and devices disclosed herein may be performed by more, less or other components, and the described methods may include more, less, or other steps. In addition, the steps may be performed in any suitable order. "Each" used in this document refers to each member of a set or each member of a subset of a set.

[0085] Although exemplary embodiments are shown in the drawings and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques shown in the drawings and described above.

[0086] Unless specifically noted otherwise, items depicted in the drawings are not necessarily drawn to scale.

[0087] All examples and conditional language described herein are intended for teaching purposes to help readers understand the present disclosure and the concepts contributed by the inventors to further develop the art, and are interpreted as not being limited to these specifically cited examples and conditions. Although the embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions and modifications may be made to the present disclosure without departing from the spirit and scope of the present disclosure.

[0088] Although specific advantages are listed above, various embodiments may include some, zero or all of the listed advantages. In addition, after reading the above drawings and descriptions, those of ordinary skill in the art may easily see other technical advantages.

[0089] It should be noted that the above-mentioned embodiments illustrate rather than limit the present disclosure, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim, "a" or "an" does not exclude a plurality, and a single feature or other unit may perform the functions of several units recited in a claim. Any reference numerals or labels in a claim should not be construed as limiting its scope.

Claims

1. A method for connecting an auxiliary electrical system to a power network of a vehicle, the method comprising: i) the auxiliary electrical system sends an activation request to the electrical power network of the vehicle; ii) in response to the activation request sent by the auxiliary electrical system, the electrical power network of the vehicle electrically couples a battery of the electrical power network of the vehicle to a power output point of the vehicle and provides an indication to the auxiliary electrical system that a power output device has been activated; iii) in response to the indication that the power output device has been enabled, the auxiliary electrical system: pre-charging a DC bus of the auxiliary electrical system; as well as A contactor of the auxiliary electrical system is closed to electrically couple the auxiliary electrical system to the power output point of the vehicle.

2. The method according to claim 1, further comprising: The auxiliary electrical system determines that there is a demand for electrical power from the electrical power network of the vehicle before sending the enable request to the electrical power network of the vehicle.

3. The method according to claim 1, further comprising: The power network pre-charges the power output device prior to providing the indication to the auxiliary electrical system that the power output device is enabled.

4. The method according to claim 1, wherein: Providing the indication that the power output device is enabled includes one or more of the following: setting an internal state of the power network to enabled; and An enable response is sent to the auxiliary electrical system indicating that the power output device has been enabled.

5. The method according to claim 1, further comprising: The auxiliary electrical system detects a voltage at the power output point before pre-charging the DC bus.

6. The method according to claim 5, wherein: Detecting the voltage at the power output point includes one or more of the following: receiving an indication of a voltage at a power output point from the vehicle power network; and The auxiliary electrical system monitors the voltage at the power output point.

7. The method according to claim 1, wherein: The auxiliary electrical system pre-charges the DC bus in any of the following ways: using a pre-charge circuit of the auxiliary electrical system, wherein the pre-charge circuit draws power from a battery; or Current is drawn from the power take-off point via a resistor by the auxiliary electrical system.

8. The method according to claim 1, wherein: When the voltage of the DC bus is within a predetermined threshold of the voltage at the power output point, the contactor of the auxiliary electrical system is closed.

9. The method according to claim 1, further comprising: The auxiliary electrical system: determining that power from the power network of the vehicle is no longer required; sending a deactivation request to the power network of the vehicle; Optionally, performing a discharge process to discharge the DC bus; and In response to the deactivation request, the electrical power network of the vehicle: electrically decoupling the vehicle battery from the power output point; and Optionally, a discharging process is performed to discharge the power output point.

10. The method according to claim 1, further comprising: In response to detecting a voltage drop at the power output point, the auxiliary electrical system opens its contactor; and Optionally, a discharge process is performed to discharge the DC bus.

11. An auxiliary electrical system configured to be connected to a power network of a vehicle, the auxiliary electrical system comprising: a connector configured to couple with the power network of the vehicle; Power distribution unit; contactors, and DC bus, Wherein, the auxiliary electrical system is configured as follows: sending an enablement request to the power network of the vehicle; and In response to an indication provided by the power network of the vehicle that a power output device of the power network of the vehicle is enabled: pre-charging the DC bus; and The contactor is closed to electrically couple an auxiliary electrical system to a power output point of the electrical power network of the vehicle.

12. A vehicle power network configured to be connected to an auxiliary electrical system, the vehicle power network comprising: Battery; a power take-off point configured to be electrically coupled to the auxiliary electrical system; and a contactor for selectively coupling the battery to the power output point, wherein the vehicle power network is configured to respond to an activation request sent by the auxiliary electrical system: electrically coupling the battery to the power output point; and An indication is provided to the auxiliary electrical system that the power take-off device is enabled.

13. A method performed by an auxiliary electrical system for connecting an auxiliary electrical system to a power network of a vehicle, the method comprising: sending an enablement request to the power network of the vehicle; and In response to an indication provided by the power network of the vehicle that a power output device of the power network of the vehicle is enabled: pre-charging a DC bus of the auxiliary electrical system; as well as A contactor of the auxiliary electrical system is closed to electrically couple the auxiliary electrical system to a power output point of the vehicle.

14. A method performed by an electrical power network of a vehicle for connecting an auxiliary electrical system to the electrical power network of the vehicle, the method comprising: In response to an enable request sent by the auxiliary electrical system: A battery of the power network of the vehicle is electrically coupled to a power take-off point of the vehicle and an indication is provided to the auxiliary electrical system that a power take-off device is enabled.

15. A computer program comprising instructions for configuring an auxiliary electrical system to connect to an electrical network of a vehicle, the auxiliary electrical system comprising: a connector configured to couple with the power network of the vehicle; Power distribution unit; contactor, and a DC bus, wherein the auxiliary electrical system is configured to: send an enable request to the power network of the vehicle; and in response to an indication provided by the power network of the vehicle that the power output device of the power network of the vehicle has been enabled: pre-charge the DC bus; and close the contactor to electrically couple the auxiliary electrical system to the power output point of the power network of the vehicle to perform the method according to claim 13.

16. A computer program comprising instructions for configuring a vehicle power network to connect to an auxiliary electrical system, the vehicle power network comprising: Battery; a power take-off point configured to be electrically coupled to the auxiliary electrical system; and a contactor for selectively coupling the battery to the power output point, wherein the vehicle power network is configured to, in response to an enable request sent by the auxiliary electrical system: electrically couple the battery to the power input point; and provide an indication to the auxiliary electrical system that the power output device has been enabled, so as to perform the method according to claim 14.

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