Vehicle power supply control system

Abstract

A control system for controlling a vehicle power supply system 200 of a vehicle. The vehicle power supply system comprises a battery subsystem 210 which is switchable between a low-voltage configurati

Description

TECHNICAL FIELD The present disclosure relates to a vehicle power supply control system. Aspects of the invention relate to a control system for controlling a vehicle power supply system of a vehicle, to a system comprising the control system, to a vehicle comprising such a system, and to a method for controlling a battery system of a vehicle. BACKGROUND Battery electric vehicles (BEVs) comprise traction motors and traction batteries for supplying electrical energy to the traction motors. BEV traction batteries can typically be recharged with electrical energy from a power supply external to the vehicle, such as electrical energy from an electrical grid. Such external power supplies are typically referred to as Electric Vehicle (EV) chargers or charging stations. EV chargers are generally classified into different levels (Levels 1,2 and 3), with higher levels being associated with higher power outputs and faster charging. Level 1 and 2 chargers provide alternating current (AC) to an on-board charger (OBC) of a vehicle, which converts the AC to direct current (DC) which, in turn, is used to charge the traction battery. In contrast, Level 3 chargers typically provide a DC power supply directly to the traction battery of a vehicle. As BEV use becomes more popular, so the demand for more, and faster, EV chargers increases. It is expected that EV chargers will become more powerful over the coming years to meet this demand. BEVs manufactured and sold today therefore need to be compatible with EV chargers having higher power outputs even than the current Level 3. It is against this background that the present invention has been developed. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a control system for controlling a vehicle power supply system of a vehicle, a system comprising the control system, a vehicle comprising such a system, and a method for controlling a battery system of a vehicle as claimed in the appended claims. According to an aspect of the present invention there is provided a control system for controlling a vehicle power supply system of a vehicle, the vehicle power supply system comprising a battery subsystem, wherein the battery subsystem is switchable between a low-voltage configuration in which a plurality of batteries are connected in parallel and a high-voltage configuration in which the plurality of batteries are connected in series, the control system comprising one or more processors collectively configured to: receive a fault signal indicative of a fault in one or more components of the vehicle power supply system; determine a fault-condition battery configuration in dependence on the fault signal; and output a control signal comprising an instruction to configure the battery subsystem in accordance with the fault-condition battery configuration. In an embodiment, the fault-condition battery configuration may prevent the battery from switching to one or both of the low-voltage configuration or the high-voltage configuration. The present invention is advantageous as the battery subsystem can be configured to allow at least some degree of vehicle, or vehicle accessory, use and battery charging, even if a fault has occurred within the vehicle power supply system. The control system comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to: receive a fault signal indicative of a fault in one or more components of the vehicle power supply system; determine a fault-condition battery configuration in dependence on the fault signal; and output a control signal comprising an instruction to configure the battery subsystem in accordance with the faultcondition battery configuration. In an embodiment, the fault-condition battery configuration may prevent the battery from switching to one or both of the low-voltage configuration or the high-voltage configuration. Optionally, the fault signal may comprise one of: a low-voltage fault signal indicative of a first voltage level being unavailable, wherein the first voltage level is associated with the plurality of batteries being connected in parallel, and wherein the control system is configured to determine a low-voltage-fault-condition battery configuration in which the plurality of batteries are connected in series, and to generate a low-voltage-fault control signal upon receipt of the low-voltage fault signal; a high-voltage fault signal indicative of a second voltage level being unavailable, wherein the second voltage level is associated with the plurality of batteries being connected in series, and wherein the control system is configured to determine a high-voltage-fault-condition battery configuration in which the plurality of batteries are connected in parallel, and to generate a high-voltage-fault control signal upon receipt of the high-voltage fault signal; or a charging port fault signal indicative of a charging port of the vehicle being irreversibly connected to the plurality of batteries, and wherein the control system is configured to determine a charging-port-fault-condition battery configuration in which the plurality of batteries are disconnected from one another, and to generate a charging-port-fault control signal upon receipt of the charging port fault signal. This is beneficial as the batteries are connected in series (high-voltage) if there is a fault in the low-voltage system, connected in parallel (low-voltage) if there is a fault in the high-voltage system, and disconnected altogether if there is a charging port where the vehicle charging port is irreversibly connected to the batteries, for example, if switches connecting the charging port to the batteries are welded closed. The low-voltage fault signal may optionally comprise: a first fault signal indicative of one or more switches controlling the parallel connection of the plurality of batteries being stuck open; a second fault signal indicative of a boost convertor of the vehicle power system being inoperative; and / or a third fault signal indicative of one or more switches controlling the connection of the plurality of batteries to the boost convertor being stuck open. Failure of various different components of the low-voltage system may therefore result in reconfiguration of the battery subsystem to the high-voltage (series) configuration. The high-voltage fault signal may comprise: a fourth fault signal indicative of one or more switches controlling the series connection of the plurality of batteries being stuck open; a fifth fault signal indicative of one or more switches controlling the direct connection of the plurality of batteries to a power distribution bus of the vehicle being stuck open. Failure of various different components of the high-voltage system may therefore result in reconfiguration of the battery subsystem to the low-voltage (parallel) configuration. In an embodiment, the charging port fault signal may comprise a sixth fault signal indicative of one or more switches controlling the connection of a charging port of the vehicle to the plurality of batteries being stuck closed. Optionally the control system may be configured to: receive a vehicle use signal indicative of: a drive mode condition in which the vehicle is being driven; a standby condition in which the vehicle is stationary and ready to pull away; a DC charging condition in which the plurality of batteries are being charged by an external DC power source; or an accessory condition in which the vehicle is prevented from being driven and in which onboard accessories are operable, wherein the control system is configured to: prevent generation of the charging-port-fault control signal upon receipt of a vehicle use signal indicative of the drive mode condition, the standby condition, or the DC charging condition; or generate the charging-port-fault control signal only upon receipt of both the charging port fault signal and a vehicle use signal indicative of the accessory condition. This is advantageous as the battery subsystem may still be used to power the vehicle for driving or pulling away manoeuvres even if there is a charging port fault since the charging port fault only has significance when the vehicle is stationary (and therefore able to be connected to an EV charger). The control system may optionally be configured to: output a first set of control signals upon determination of the low-voltage-fault-condition battery configuration, wherein the first set of control signals comprise the low-voltage-fault control signal, an instruction to close the one or more switches controlling the direct connection of the plurality of batteries to the power distribution bus of the vehicle, and an instruction to set the boost convertor into a standby mode; or output a second set of control signals upon determination of the high-voltage-fault-condition battery configuration, wherein the second set of control signals comprise the high-voltage-fault control signal, an instruction to close the one or more switches controlling the connection of the plurality of batteries to the boost convertor, and an instruction to set the boost convertor into an active mode. This is advantageous as key components of the respective low-voltage / high-voltage power supply system can be disabled in the event of a low-voltage / high-voltage fault. The control system may be configured to: receive a charger type connection signal indicative of the type of charger connected to the charging port of the vehicle; determine if the charger type is alternating current; and output a control signal comprising an instruction to set the boost convertor into an active mode if the charger type is alternating current and the fault-condition-battery-configuration is the low-voltage-fault-condition battery configuration. This is beneficial as the batteries may still be charged by an AC power source even if there is a fault in the low-voltage system. In an embodiment the control system may be configured to: receive a charger voltage signal indicative of the rated voltage of a charger connected to the charging port of the vehicle; determine if the rated voltage of the charger is compatible with the fault-condition-battery-configuration; and output a control signal comprising an instruction to prevent charging if the rated voltage of the charger is not compatible with the fault-condition-battery-configuration. This prevents charging if the battery subsystem is unable to be configured appropriately for the rated power of the connected EV charger. According to another aspect of the invention, there is provided a system comprising a control system as described above and a battery subsystem comprising: a plurality of batteries; one or more switches for controlling a parallel connection configuration of the plurality of batteries; and one or more switches for controlling a series connection configuration of the plurality of batteries. Optionally, the system may comprise a vehicle power supply system, wherein the vehicle power supply system comprises: a power distribution bus a boost convertor connected to the power distribution bus; one or more switches for controlling the connection of the plurality of batteries to the boost convertor; one or more switches for controlling the direct connection of the plurality of batteries to the power distribution bus; and one or more switches for controlling the connection of a charging port of the vehicle to the plurality of batteries. According to a further aspect of the invention, there is provided a vehicle comprising a system or a control system as described above. According to yet another aspect of the invention, there is provided a method for controlling a vehicle power supply system of a vehicle, the vehicle power supply system comprising a battery subsystem, wherein the battery subsystem is switchable between a low-voltage configuration in which a plurality of batteries are connected in parallel and a high-voltage configuration in which the plurality of batteries are connected in series, the method comprising: receiving a fault signal indicative of a fault in one or more component of the vehicle power supply system; determining a fault-condition battery configuration in dependence on the fault signal; and outputting a control signal comprising an instruction to configure the battery subsystem in accordance with the fault-condition-battery-configuration, wherein in the fault-condition battery configuration the battery subsystem is prevented from switching to one or both of the low-voltage configuration or the high-voltage configuration. According to a still further aspect of the invention, there is provided computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the method described above. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle in accordance with an embodiment of the invention; Figure 2 shows is a schematic view of a vehicle power supply system of the vehicle of Figure 1; Figure 3 shows a schematic representation of a control system in accordance with an embodiment of the invention; Figure 4 schematically illustrates a system comprising the control system of Figure 3 and the vehicle power supply system of Figure 2; and Figure 5 shows a flow chart depicting a method in accordance with an embodiment of the invention. DETAILED DESCRIPTION A vehicle 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1. As shown in Figure 1, a control system 110 for controlling a vehicle power supply system 200 of the vehicle 100 is installed in the vehicle 100. Figure 2 shows is a schematic view of a vehicle power system 200 of the vehicle 100. The power supply system 200 generally comprises a traction battery or battery pack 210, a load bus 220, and an on-board charger (OBC) 230. The battery pack 210 comprises a battery subsystem of the power supply system 200. In the present embodiment, the vehicle 100 is a battery electric vehicle (BEV), but in other embodiments, the vehicle 100 may be a hybrid electric vehicle (HEV). In the present embodiment, the battery subsystem 210 comprises first and second batteries 211,212 which may be connected in series by closure of battery switch 213, or in parallel by closure of battery switches 214, 215. In Figure 2, battery switch 213 is shown as closed for illustrative purposes. When battery switch 213 is closed, battery switches 214, 215 are open to prevent the batteries being connected in series and in parallel at the same time. Similarly, when battery switches 214, 215 are closed, battery switch 213 is open. The battery subsystem 210 is capable of being charged by either a 400V or 800V supply. Having the capability to accept, for example, substantially 800V (e.g. a voltage between 450V to 850V) or substantially 400V (e.g. a voltage between 250V to 450V) at the same input allows for a flexible system capable of operating and charging with different voltage requirements. The load bus 220 can be directly connected to the battery subsystem 210 by closing load bus switches 216, 217. When the load bus switches 216, 217 are closed, and the battery subsystem 210 is configured with the batteries 211,212 connected in series, the battery subsystem 210 provides a high-voltage, i.e. substantially 800V, supply to the load bus 220. The load bus 220 comprises circuitry which connects the traction battery 210 to one or more inverters of the vehicle 100 which, in turn, control one or more electric motors for providing motive power to the vehicle 100 during driving. In the present embodiment, the load bus 220 comprises high voltage and ground connections 221 to an inverter mounted in the front of the vehicle, and respective high voltage and ground connections 222 to an inverter mounted in the rear of the vehicle. The load bus 220 additionally comprises a bi-directional DCDC converter 223 for converting the high-voltage supply from the traction battery 210 to a nominal 12V supply for powering auxiliary vehicle systems and for providing power to a nominal 12V battery 224. The vehicle 100 is provided with an electrical charging port 225 for receiving an electrical charging plug of an external electrical power supply. In Figure 2, the port 225 is shown schematically and comprises respective first, second and third inlet portions 226, 227, 228. In the present embodiment, the first and second inlet portions 226, 227 are configured to receive respectively the pins of a DC level 3 EV charger. Charging port switches 241,242 are operable to directly connect the first and second inlet portions 226, 227 to the battery subsystem 210. Accordingly, when the vehicle power system 200 is connected to an external DC level 3 power supply via the first and second inlet portions 226, 227, and the battery subsystem is arranged in the series connection configuration with battery switch 213 closed and battery switches 214, 215 open, the batteries 211, 212 are able to be charged by power provided by the DC level 3 EV charger. The third inlet portion 228 of the port 225 is configured to receive the pins of an AC level 1 or level 2 EV charger. The third inlet portion 228 of the charging port 225 is connected directly to the OBC 230. The OBC 230 comprises an AC to DC converter 231 and a boost convertor 232. OBC switches 233, 234 are operable to connect the OCB 230 to the battery subsystem 210. Accordingly, when the vehicle power system 200 is connected to an external AC power supply, and the battery subsystem is arranged in the parallel connection configuration with battery switch 213 open and battery switches 214, 215 closed, the batteries 211,212 are able to be charged by power provided by the AC level 31 or level 2 EV charger. It is not possible to drive the vehicle 100 when the battery subsystem is arranged in the low-voltage parallel connection configuration. However, the boost convertor 232 enables the supply of substantially 800V to the load bus 220 even when the battery subsystem is arranged in the low-voltage parallel connection configuration to enable the battery subsystem 210 to be used to power vehicle accessories such as climate control and entertainment to avoid rapid depletion of the nominal 12V battery 224. The OBC switches 233, 234 are closed in this mode of operation. It is possible that one or more of the components of the vehicle power system 200 may fail. If this happens, one or both of the high-voltage (series) or low-voltage (parallel) configurations of the battery subsystem 210 will be unavailable. This may be due to a fault with a battery switch 213, 214, 215, a load bus switch 216, 217, an OBC switch 233, 234, a charging point switch 241, 242, or the boost convertor 232. For example, if the series battery switch 213 is stuck open, it is not possible to connect the battery subsystem in the high-voltage series configuration, and only the low-voltage parallel configuration will be available. Similarly, if the parallel battery switches 214, 215 are stuck open, it is not possible to connect the battery subsystem 210 in the low-voltage parallel configuration, and only the high-voltage series configuration will be available. Failure of the battery switches 213, 214, 215 is not the only failure mode which will restrict the availability of the high-voltage or low-voltage battery configurations. If there is a failure of a load bus switch 216, 217 the high-voltage series battery configuration will not be available for use as there will be no way to transfer the power from the battery subsystem 210 to the load bus 220. Similarly, if there is a failure of an OBC switch 233, 234 the low-voltage parallel battery configuration will not be available for use as there will be no way to transfer the power from the battery subsystem 210 to the load bus 220 at the required substantial voltage of 800V. The low-voltage parallel battery configuration will also not be available for use if there is a fault in the boost convertor 232 as, again, there will be no way to transfer the power from the battery subsystem 210 to the load bus 220 at the required substantial voltage of 800V. If there is a failure of a charging point switch 241,242 such that one or both of the charging point switches 241,242 are welded closed, it is not possible to disconnect the inlet portions 226, 227 of the charging port 225 from the battery subsystem 210. This would result in the inlet portions 226, 227 being connected to the battery subsystem 210 at all times. To prevent this, when required, the batteries 211, 212 of the battery subsystem 210 must be disconnected from each other by opening the battery switches 213, 214, 215. If the vehicle 100 is in a drive mode condition in which it is being driven, or if the vehicle 100 is a standby condition in which it is stationary and ready to pull away, or if the vehicle 100 is a charging condition in which the batteries 211,212 are being charged by a DC EV charger, the batteries 211,212 may be connected in the high-voltage series configuration by closure of battery switch 213 even if a charging point switch 241, 242 is welded closed. However, if the vehicle 100 is an accessory condition in which the vehicle 100 is prevented from being driven and in which onboard accessories are operable (powered by the nominal 12V battery 224), the batteries 211, 212 are disconnected from one another by opening battery switches 213, 214, 215 if a charging point switch 241,242 is welded closed. With reference to Figure 3, there is schematically illustrated a control system 110 for controlling the vehicle power supply system 200 of the vehicle 100. The control system 110 comprises one or more processors 120 collectively configured to receive a fault signal 140 indicative of a fault in one or more components of the vehicle power supply system 200. The control system 110 is configured to determine a fault-condition battery configuration in dependence on the fault signal 140, and output a control signal 150 comprising an instruction to configure the battery subsystem 210 in accordance with the fault-condition battery configuration. The determined fault-condition battery configuration prevents the battery subsystem 210 from switching to one or both of the low-voltage parallel configuration, or the high-voltage series configuration. The control system 110 comprises one or more controllers 111 collectively comprising at least one electronic processor 120 having an electrical input for receiving the input signal 140, and at least one memory device 130 electrically coupled to the at least one electronic processor 120. The at least one memory device 130 has instructions stored therein, and the at least one electronic processor 120 is configured to access the at least one memory device 130 and execute the instructions thereon so as to receive the fault signal 140 indicative of a fault in one or more components of the vehicle power supply system 200, determine a suitable faultcondition battery configuration in dependence on the fault signal, and output a control signal 150 comprising an instruction to configure the battery subsystem 210 in accordance with the fault-condition battery configuration. The fault signal 140 can comprise a low-voltage fault signal which is indicative of a first voltage level being unavailable, wherein the first voltage level is associated with the plurality of batteries being connected in parallel. Upon receipt of the low-voltage fault signal, the control system 110 is configured to determine a low-voltage-fault-condition battery configuration in which the plurality of batteries are connected in series (i.e. the low-voltage parallel battery configuration is unavailable so the high-voltage series configuration must be adopted). The control system 110 then generates a low-voltage-fault control signal comprising an instruction to configure the battery subsystem 210 in accordance with the low-voltage-fault-condition battery configuration. The fault signal 140 can comprise a high-voltage fault signal which is indicative of a second voltage level being unavailable, wherein the second voltage level is associated with the plurality of batteries being connected in series. Upon receipt of the high-voltage fault signal, the control system 110 is configured to determine a high-voltage-fault-condition battery configuration in which the plurality of batteries are connected in parallel (i.e. the high-voltage series battery configuration is unavailable so the low-voltage parallel configuration must be adopted). The control system 110 then generates a high-voltage-fault control signal comprising an instruction to configure the battery subsystem 210 in accordance with the high-voltage-fault-condition battery configuration. The fault signal 140 can comprise a charging port fault signal indicative of a charging port of the vehicle being irreversibly connected to the plurality of batteries. Upon receipt of the charging point fault signal, the control system 110 is configured to determine a charging-port-fault-condition battery configuration in which the plurality of batteries are disconnected from one another. The control system 110 then generates a charging-port-fault control signal comprising an instruction to configure the battery subsystem 210 in accordance with the high-charging-point-fault-condition battery configuration. The low-voltage fault signal can comprise a first fault signal indicative of one or both battery switches 214, 215 which control the parallel connection of the batteries 211,212 being stuck open. The low-voltage fault signal can also comprise a second fault signal indicative of the boost convertor 232 of the vehicle power system 200 being inoperative. Additionally, the low-voltage fault signal can comprise a third fault signal indicative of one or more of the OBC switches 231,232 being stuck open. The high-voltage fault signal can comprise a fourth fault signal indicative of indicative of the battery switch 213 controlling the series connection of the batteries 211,212 being stuck open. The high-voltage fault signal can also comprise a fifth fault signal indicative of one or both of the load bus switches 216, 217 being stuck open. The charging port fault signal can comprise a sixth fault signal indicative of one or both of the charge port switches 241,242 being stuck closed. In an embodiment, the control system 110 may be configured to receive a vehicle use signal indicative of an operational condition of the vehicle 100. The operational condition may be a drive mode condition in which the vehicle is being driven, a standby condition in which the vehicle is stationary and ready to pull away, a DC charging condition in which the plurality of batteries are being charged by an external DC power source, or an accessory condition in which the vehicle is prevented from being driven and in which onboard accessories are operable. To enable use of the battery subsystem 210 to power the vehicle 100 in certain circumstances, the control system 110 is configured to prevent generation of the charging-port-fault control signal upon receipt of a vehicle use signal indicative of the drive mode condition, the standby condition, orthe DC charging condition. To prevent permanent connection of the battery subsystem 210 to the inlet portions 226, 227 of the charging port in certain circumstances, the control system 110 is configured to generate the charging-port-fault control signal only upon receipt of both the charging port fault signal and a vehicle use signal indicative of the accessory condition. The control system 110 may be configured to output a first set of control signals upon determination of the low-voltage-fault-condition battery configuration, wherein the first set of control signals comprise the low-voltage-fault control signal, an instruction to close the load bus switches 216, 217, and an instruction to set the boost convertor 232 into a standby mode. This first set of control signals configures the vehicle power supply system 200 for high-voltage use. The control system 110 may also be configured to or output a second set of control signals upon determination of the high-voltage-fault-condition battery configuration, wherein the second set of control signals comprise the high-voltage-fault control signal, an instruction to close the OBC switches 233, 234, and an instruction to set the boost convertor 232 into an active mode. This second set of control signals configures the vehicle power supply system 200 for low-voltage use. The control system 110 may be configured to receive a charger type connection signal which is indicative of the type of charger connected to the charging port 225 of the vehicle 100. The control system 110 may be configured to determine if the chargertype is alternating current (AC), and to output a control signal comprising an instruction to set the boost convertor 232 into an active mode if the charger type is AC and the faultcondition-battery-configuration is the low-voltage-fault-condition battery configuration. This allows the batteries 211,212 to be charged by an AC power source even if there is a fault in the low-voltage system. In an embodiment the control system 110 may be configured to receive a charger voltage signal which is indicative of the rated voltage of a charger connected to the charging port 225 of the vehicle 100. The control system 110 may be configured to determine if the rated voltage of the charger is compatible with the faultcondition-battery-configuration, and to output a control signal comprising an instruction to prevent charging if the rated voltage of the charger is not compatible with the fault-condition-battery-configuration. This prevents charging if the battery subsystem 210 is unable to be configured appropriately for the rated power of the connected EV charger. The control system 110 as illustrated in Figure 3 comprises one controller 111, although it will be appreciated that this is merely illustrative. The controller 111 comprises an input means 141 and an output means 151. The input means 141 may comprise an electrical input 141 of the controller 111. The output means 151 may comprise an electrical output 151 of the controller 111. Figure 4 schematically illustrates a system 300 comprising the control system 110 and the vehicle power supply system 200. Figure 5 schematically illustrates a method 400 for controlling the vehicle power supply system 200 of the vehicle100. The method 400 comprising a first step 401 in which a fault signal 440 is received, the fault signal 440 being indicative of a fault in one or more component of the vehicle power supply system 200. In a second step 402, a fault-condition battery configuration is determined in dependence on the fault signal 440, and in a third step 403 a control signal 450 comprising an instruction to configure the battery subsystem in accordance with the fault-condition-battery-configuration is output. The fault-condition battery configuration prevents the battery subsystem from being configured in one or both of the low-voltage parallel configuration or the high-voltage series configuration. The method 400 may be performed by the control system 110 illustrated in Figure 3. In particular, the memory 130 may comprise computer-readable instructions which, when executed by the processor 120, perform the method 400 according to an embodiment of the invention. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A control system for controlling a vehicle power supply system of a vehicle, the vehicle power supply system comprising a battery subsystem, wherein the battery subsystem is switchable between a low-voltage configuration in which a plurality of batteries are connected in parallel and a high-voltage configuration in which the plurality of batteries are connected in series, the control system comprising one or more processors collectively configured to:receive a fault signal indicative of a fault in one or more components of the vehicle power supply system;determine a fault-condition battery configuration in dependence on the fault signal; and output a control signal comprising an instruction to configure the battery subsystem in accordance with the fault-condition battery configuration, wherein in the fault-condition battery configuration the battery subsystem is prevented from switching to one or both of the low-voltage configuration or the high-voltage configuration.

2. The control system as claimed in claim 1, wherein the fault signal comprises one of:a low-voltage fault signal indicative of a first voltage level being unavailable, wherein the first voltage level is associated with the plurality of batteries being connected in parallel, and wherein the control system is configured to determine a low-voltage-fault-condition battery configuration in which the plurality of batteries are connected in series, and to generate a low-voltage-fault control signal upon receipt of the low-voltage fault signal;a high-voltage fault signal indicative of a second voltage level being unavailable, wherein the second voltage level is associated with the plurality of batteries being connected in series, and wherein the control system is configured to determine a high-voltage-fault-condition battery configuration in which the plurality of batteries are connected in parallel, and to generate a high-voltage-fault control signal upon receipt of the high-voltage fault signal; ora charging port fault signal indicative of a charging port of the vehicle being irreversibly connected to the plurality of batteries, and wherein the control system(110) is configured to determine a charging-port-fault-condition battery configuration in which the plurality of batteries are disconnected from one another, and to generate a charging-port-fault control signal upon receipt of the charging port fault signal.

3. The control system as claimed in claim 2, wherein the low-voltage fault signal comprises:a first fault signal indicative of one or more switches controlling the parallel connection of the plurality of batteries being stuck open;a second fault signal indicative of a boost convertor of the vehicle power system being inoperative; and / ora third fault signal indicative of one or more switches controlling the connection of the plurality of batteries to the boost convertor being stuck open.

4. The control system as claimed in claim 2 or claim 3, wherein the high-voltage fault signal comprises:a fourth fault signal indicative of one or more switches controlling the series connection of the plurality of batteries being stuck open;a fifth fault signal indicative of one or more switches controlling the direct connection of the plurality of batteries to a power distribution bus of the vehicle being stuck open.

5. The control system as claimed in any of claims 2 to 4, wherein the charging port fault signal comprises a sixth fault signal indicative of one or more switches controlling the connection of a charging port of the vehicle to the plurality of batteries being stuck closed.

6. The control system as claimed in claim 5 configured to:receive a vehicle use signal indicative of:a drive mode condition in which the vehicle is being driven;a standby condition in which the vehicle is stationary and ready to pull away;a DC charging condition in which the plurality of batteries are being charged by an external DC power source; oran accessory condition in which the vehicle is prevented from being driven and in which onboard accessories are operable,wherein the control system is configured to:prevent generation of the charging-port-fault control signal upon receipt of a vehicle use signal indicative of the drive mode condition, the standby condition, or the DC charging condition; orgenerate the charging-port-fault control signal only upon receipt of both the charging port fault signal and a vehicle use signal indicative of the accessory condition.

7. The control system as claimed in claim 5 or 6 configured to:output a first set of control signals upon determination of the low-voltage-fault-condition battery configuration, wherein the first set of control signals comprise the low-voltage-fault control signal, an instruction to close the one or more switches controlling the direct connection of the plurality of batteries to the power distribution bus of the vehicle, and an instruction to set the boost convertor into a standby mode; oroutput a second set of control signals upon determination of the high-voltage-fault-condition battery configuration, wherein the second set of control signals comprise the high-voltage-fault control signal, an instruction to close the one or more switches controlling the connection of the plurality of batteries to the boost convertor, and an instruction to set the boost convertor into an active mode.

8. The control system as claimed in claim 7 configured to:receive a charger type connection signal indicative of the type of charger connected to the charging port of the vehicle;determine if the charger type is alternating current; andoutput a control signal comprising an instruction to set the boost convertor into an active mode if the charger type is alternating current and the fault-condition-battery-configuration is the low-voltage-fault-condition battery configuration.

9. The control system as claimed in any preceding claim configured to:receive a charger voltage signal indicative of the rated voltage of a charger connected to the charging port of the vehicle;determine if the rated voltage of the charger is compatible with the fault-condition-battery-configuration; andoutput a control signal comprising an instruction to prevent charging if the rated voltage of the charger is not compatible with the fault-condition-battery-configuration.

10. A system comprising the control system of any preceding claim and a battery subsystem comprising: a plurality of batteries;one or more switches for controlling a parallel connection configuration of the plurality of batteries; andone or more switches for controlling a series connection configuration of the plurality of batteries.

11. The system, wherein the vehicle power supply system comprises: a power distribution bus;a boost convertor connected to the power distribution bus;one or more switches for controlling the connection of the plurality of batteries to the boost convertor;one or more switches for controlling the direct connection of the plurality of batteries to the power distribution bus; andone or more switches for controlling the connection of a charging port of the vehicle to the plurality of batteries.

12. A vehicle comprising the system of claim 10 or 11 or the control system of claims 1 to 9.

13. A method for controlling a vehicle power supply system of a vehicle, the vehicle power supplysystem comprising a battery subsystem, wherein the battery subsystem is switchable between a low-voltage configuration in which a plurality of batteries are connected in parallel and a high-voltage configuration in which the plurality of batteries are connected in series, the method comprising:receiving a fault signal indicative of a fault in one or more component of the vehicle power supply system;determining a fault-condition battery configuration in dependence on the fault signal; and outputting a control signal comprising an instruction to configure the battery subsystem in accordance with the fault-condition-battery-configuration, wherein in the fault-condition battery configuration the battery subsystem is prevented from switching to one or both of the low-voltage configuration or the high-voltage configuration.14

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