Power system control

Abstract

A control system (200-Fig.2) for controlling a power system 300 of a vehicle, the power system comprising: a high voltage (HV) battery 340; a first DC-DC converter 350; and a second DC-DC converter 360, the HV battery being selectively connected to a low voltage (LV) bus 330 via the first or second DC-DC converter. The control system comprises one or more processors (220-Fig.2) collectively configured to: receive information (260-Fig.2) indicative of an operating state of the vehicle; determine, in dependence of the received operating state, a control signal (270-Fig.2) to connect the HV battery to the LV bus via one of the DC-DC converters; and output the determined control signal to connect the HV battery to the LV bus. During a first operating state (e.g., high power loads on the LV bus), a first switch S1 may be closed to couple the HV battery to the LV bus via the first DC-DC converter, and a second switch S2 may be opened. During a second operating state (e.g., low power loads on the LV bus), the second switch may be closed to couple the HV battery to the LV bus via the second DC-DC converter, and the first switch may be opened.

Description

TECHNICAL FIELD The present disclosure relates to a power system for a vehicle. Aspects of the invention relate to a control system for controlling a power system of a vehicle, a power system of a vehicle, a vehicle and a method for operating a control system. BACKGROUND It is known to provide both high voltage and low voltage components in vehicles. Low voltage components may provide important vehicle functions such as assisted steering, braking, and advanced driving assistance systems (ADAS) amongst other functions, and may be typically connected to a low voltage bus such as a 12V bus, optionally with a low voltage battery connected to the low voltage bus. In conventional electric and hybrid vehicles, the low voltage bus and low voltage battery may be powered and / or charged by electrical energy output by a high voltage (such as 400V or 800V) battery, which may be converted to lower voltage by a DC-DC convertor. When the vehicle is in a standby mode, the DC-DC converter stops performing the power conversion, in which case the low voltage battery has to provide any power required to the low voltage bus. However, rising power demands of ADAS systems means that the low voltage battery may become incapable of supplying the required power during this time or may risk complete battery depletion. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a control system for controlling a power system of a vehicle, a power system of a vehicle, a vehicle and a method for operating a control system as claimed in the appended claims. The disclosure provides a technique for controlling a power system of a vehicle, the power system comprising a high voltage battery, a first DC-DC converter and a second DC-DC converter. The high voltage battery is selectively connected to a low voltage bus via either the first DC-DC converter or the second DC-DC converter in dependence on the operating state of the vehicle. According to an aspect of the present invention, there is provided a control system for controlling a power system of a vehicle, the power system comprising a high voltage battery, a first DC-DC converter and a second DC-DC converter, the high voltage battery being selectively connected to a low voltage bus via the first DC-DC converter or the second DC-DC converter, the control system comprising one or more processors collectively configured to: receive information indicative of an operating state of the vehicle; determine, in dependence of the received operating state, a control signal to connect the high voltage battery to the low voltage bus via one of the first DC-DC converter and the second DC-DC converter; and output the determined control signal to connect the high voltage battery to the low voltage bus. In this way, the high voltage battery continues to supply the low voltage loads during a standby mode e.g., when the vehicle is in a parked state and the key has not been inserted. This prevents the low voltage battery from being susceptible to full discharge during standby mode, the risk of which is increased with the rising ADAS loads. Moreover, the second converter provides more efficient power management at standby modes when supplying relatively low power requirements from the high voltage battery. Optionally, connecting the high voltage battery to the low voltage bus via the first DC-DC converter or the second DC-DC converter may cause the power system to: draw electrical power from the high voltage battery; convert the electrical power to a lower voltage; and supply the converted electrical power to the low voltage bus for supplying a low voltage load. Optionally, determining the control signal may further comprise determining a power requirement of a load connected to the low voltage bus in dependence on the received operating state. As such, the high voltage battery may be connected to the low voltage bus via either the first DC-DC converter or the second DC-DC converter depending on the power requirements of the vehicle’s current operating state. Optionally, the first DC-DC converter may be a high power DC-DC converter and the second DC-DC converter may be a low power DC-DC converter. The control signal may comprise further instructions to: connect, in dependence of the received operating state, the high voltage battery to the low voltage bus via the first DC-DC converter during periods of high power loads on the low voltage bus or to connect, in dependence of the received operating state, the high voltage battery to the low voltage bus via the second DC-DC converter during periods of low power loads on the low voltage bus. This ensures that an adequately power sized DC-DC converter supplies the necessary high or low loads to allow for higher efficiency power supply, depending on the operating state of the vehicle. For example, during normal operating mode (i.e., when the occupants are interacting with the vehicle in some way), the high voltage battery may be connected to the low voltage bus via a high power DC-DC converter to provide the higher load demands. However, in standby mode where the load demand is reduced, a low power DC-DC converter may be used to connect the high voltage battery to the low voltage bus, thus preventing the low voltage battery from fully discharging if the vehicle is turned off for long periods of time. Optionally, high power loads on the low voltage bus may be considered loads that are greater than 50W. Optionally, low power loads on the low voltage bus may be considered loads that are less than 50W. The control signal may comprise instructions to: connect the high voltage battery to the low voltage bus via the first DC-DC converter during a first operating state and connect the high voltage battery to the low voltage bus via the second DC-DC converter during a second operating state. Optionally, during the first operating state of the vehicle, the control signal may comprise instructions to: close a first switch, the first switch being a switch that couples the high voltage battery to the low voltage bus via the first DC-DC converter; and open a second switch, the second switch being a switch that couples the high voltage battery to the low voltage bus via the second DC-DC converter. Optionally, during the second operating state of the vehicle, the control signal may comprise instructions to: open a first switch, the first switch being a switch that couples the high voltage battery to the low voltage bus via the first DC-DC converter; and close the second switch, the second switch being a switch that couples the high voltage battery to the low voltage bus via the second DC-DC converter. As such, the control system may be configured to control a set of switches to connect the high voltage battery to the low voltage bus via either the first DC-DC converter or the second DC-DC converter depending on the operating state of the vehicle. This ensures that the most suitable DC-DC converter is always supplying the low voltage loads based upon the power requirements associated with the operating state of the vehicle. The first operating state of the vehicle may be a state wherein one or more components of the vehicle are receiving electrical power above a predefined threshold. For example, the predefined threshold may be 50W. As such, the first operating state may be considered to be a normal operating mode of the vehicle, wherein one or more electrical components of the vehicle are in use and require electrical power above a particular level. This may include a user driving the vehicle, or the occupants interacting with vehicle in some way (e.g., the infotainment system or heating system) even when the vehicle is stationary, wherein said interactions correspond to functions requiring high power loads. The second operating state of the vehicle may be a state wherein the vehicle is parked and wherein the one or more components of the vehicle are receiving zero electrical power and / or electrical power below the predefined threshold. As such, the second operating state may be considered to be a standby mode, when the vehicle is in a parked state and the key has not been inserted. Optionally, the vehicle may be in standby mode when there is no user interaction with any of the electrical components of the vehicle, and / or the interactions with the vehicle correspond to functions requiring low power loads. The second DC-DC converter may further supply converted electrical power to a low voltage battery during the second operating state of the vehicle to maintain the state of charge of the low voltage battery, the low voltage battery being connected to the low voltage bus. This ensures that the low voltage battery is never ran to complete discharge. Thus, the low voltage battery can still be used for startup operations and the like, when required, e.g., when the vehicle enters the first operating state. Optionally, in response to detecting a low state of charge of the low voltage battery, the control signal may cause the first DC-DC converter or the second DC-DC converter to charge the low voltage battery. The second DC-DC converter may supply converted electrical power in the range of 20W-50W, or optionally in the range of 40W-50W. The first DC-DC converter may supply converted electrical power of greater than 1,5kW, or optionally more than 2kW. According to another aspect of the invention, there is provided a power system of a vehicle, the power system comprising the control system of any preceding claim, and further comprising: the high voltage battery; the first DC-DC converter; the second DC-DC converter; the low voltage bus; and the first DC-DC converter and second DC-DC converter being configured to, in dependence on receiving the control signal, connecting the high voltage battery to the low voltage bus via the first DC-DC converter or the second DC-DC converter, such that the first DC-DC converter or the second DC-DC converter draws electrical power from the high voltage battery, converts the electrical power to a lower voltage; and supplies the converted electrical power to the low voltage bus for supplying a low voltage load. In doing so, the high voltage battery continues to supply the low voltage loads during standby mode i.e., when the vehicle is in a parked state and the key has not been inserted. This prevents the low voltage battery from being susceptible to full discharge during standby mode, the risk of which is increased with the rising ADAS loads. Moreover, the second converter provides more efficient power management at standby modes when supplying relatively low power requirements from the high voltage battery. Optionally, the low voltage bus may be a 12V bus. Optionally, the high voltage battery may be an 800V battery. The at least one high voltage battery may comprise a plurality of high voltage battery packs arranged in series with one another. In some cases, the second DC-DC converter may be an auxiliary DC-DC converter, the second auxiliary DC-DC converter may be arranged such that during a first operating state of the vehicle the auxiliary DC-DC converter delivers isolated voltage supplies to one or more components of the first DC-DC converter. The auxiliary DC-DC converter may be a component of the first DC-DC converter such that when it not being used to supply power to the low voltage bus, it provides different isolated voltage levels which act as a power supply to different integrated circuits (IC) of the first DC-DC converter. For example, it supplies the isolated voltage levels for HV driver input voltages which aid in powering the gate drivers in the first DC-DC converter. Optionally, the second DC-DC converter may be an auxiliary DC-DC converter integrated within the first DC-DC converter. Optionally, the second DC-DC converter may be a micro DC-DC converter, the second DC-DC converter being arranged to only supply electrical power to the low voltage bus of the vehicle. As such, the micro DC-DC converter may be bespoke made for the purpose of supplying the low voltage bus to thereby provide higher efficiency. The micro DC-DC converter may supply converted electrical power in the range of 20W-80W, or optionally in the range of 40W-50W. The first DC-DC converter may supply converted electrical power of greater than 1,5kW, or optionally greater than 2kW. According to another aspect of the present invention, there is provided a vehicle comprising the control system as mentioned above or the power system as mentioned above. According to yet another aspect of the present invention, there is provided a method for operating a control system for controlling a power system of a vehicle, the power system comprising a high voltage battery, a first DC-DC converter and a second DC-DC converter, the high voltage battery being selectively connected to a low voltage bus via the first DC-DC converter or the second DC-DC converter, the method comprising: receiving information indicative of an operating state of the vehicle; determining, in dependence of the received operating state, a control signal to connect the high voltage battery to the low voltage bus via one of the first DC-DC converter and the second DC-DC converter; and outputting the determined control signal to connect the high voltage battery to the low voltage bus. According to another aspect of the present invention, there is provided computer readable instructions, which when executed by a processor, are arranged to perform the method of the preceding statement. 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 block diagram illustrating a power system of a vehicle according to the prior art; Figure 2 shows a block diagram illustrating a control system of a vehicle according to an embodiment of the present invention; Figure 3A shows a block diagram illustrating a power system of a vehicle according to an embodiment of the present invention; Figure 3B shows a block diagram illustrating a power system of a vehicle according to an embodiment of the present invention; Figure 4 shows a flow chart showing a method according to an embodiment of the present invention; and Figure 5 shows a vehicle in accordance with an embodiment of the invention. DETAILED DESCRIPTION The present disclosure relates to managementof power supply to a low voltage bus from a high voltage battery or high voltage battery packs. As will be described below, various embodiments include a control system, a power system, a vehicle and a method. An electric vehicle such as a battery electric vehicle (BEV) or a hybrid vehicle such as a mild-hybrid electric vehicle (MHEV) or plug-in-hybrid electric vehicle (PHEV) typically includes at least one high voltage battery pack which is used in part to drive an electric motor to drive the vehicle. The vehicle typically also includes a low voltage battery and / or low voltage bus to power auxiliary functions of the vehicle, such as infotainment system, power steering, automatic braking, or ADAS functions. In some cases, the high voltage battery pack may be used as part of a power system of a vehicle to power the low voltage bus and low voltage loads. In this case, a DC-DC convertor is typically used to step up or down the voltage and / or current of the electrical power output by the high voltage battery pack such that it is suitable for use by the low voltage components. However, since the high voltage battery and the associated DC-DC converter are not designed for supplying low loads challenges such as high voltage battery drain, DC-DC converter reliability and derating arise. In otherwords, during off grid parking mode, the high voltage-low voltage (HV-LV) converter goes into standby mode and stops power processing. During this time interval, the LV battery has to support the standby LV load. With advancement in ADAS features, the rising power demand in standby mode increases the probability of LV battery depletion (greater risk in very low temperatures). Once the LV battery is depleted, the only way to start the BEV again is through a jumpstart mechanism from an external LV power supply. The present disclosure relates to an improved power system in which the high voltage battery of a vehicle is connected to the low voltage bus via a secondary DC-DC converter during times when the vehicle is in standby mode. Standby mode may be considered as an operating state in which the vehicle is parked and not in use, that is to say, a user is not interacting with the vehicle in any way. However, it will also be appreciated that standby mode may also include some user interaction with the vehicle (e.g., via informatic and / or telematic systems), such as interactions with the vehicle via mobile applications, vehicle status checks, remote unlocking, and other low power operations. As such, standby mode may also correspond to an operating state wherein the vehicle is parked and the components of the vehicle are receiving zero electrical power and / or electrical power below a predefined threshold. For example, the predefined threshold may be 50W. It will of course be appreciated that this threshold may be any suitable threshold depending on factors such as the power requirements of the various components and functions of the vehicle. When the vehicle is in normal operating mode, the high voltage battery pack is connected to the low voltage bus via a first DC-DC converter. Normal operating mode may be considered as an operating state in which the vehicle is in normal use and wherein one or more components of the vehicle are receiving power. In this respect, it will be appreciated that normal use may correspond to an operating state in which one or more components of the vehicle are receiving power above the predefined threshold. As another example, standby mode may correspond to an operating state in which the vehicle is in a parked state and only a predefined set of functions are in use, wherein the predefined set of functions require low power loads. In such cases, the normal operating mode may correspond to an operating state in which additional functions are in use, wherein the additional functions require high power loads. The use of a first and second DC-DC converter enables the provisions of more efficient power management as the secondary DC-DC converter can be more suitably sized for the power requirements associated with the low voltage loads of the vehicle in standby mode. In this context, low voltage loads may refer to loads such as headlights, power steering, radio, USB charging, LiDAR, GPS, Ultrasound, IMU, RADAR, camera, computer processing etc. Figure 1 shows an example power system 100 in accordance with the prior art. The power system 100 comprises a low voltage battery 110, load voltage load 120, low voltage bus 130, high voltage battery 140 and a DC-DC converter 150. The DC-DC converter 150 is coupled to the low voltage bus 130 via a switch (S1). In this example, the switch S1 is shown as being closed. In this arrangement, the low voltage load 120 will be supplied from the low voltage battery 110 during periods of low load, e.g. when the vehicle is in standby mode, and the low voltage load 120 will be supplied from the high voltage battery 140 via the DC-DC converter 150 during periods of high load e.g., normal operating mode of the vehicle. However, as electric vehicles continue to develop and become more complex the amount of low voltage loads 120 are also increasing. This is largely due to the increase in ADAS systems. These ADAS systems provide low voltage loads 120 during standby mode and normal operating mode. Thus, a problem arises wherein the low voltage battery 110 is no longer sufficient to supply the low voltage loads 120 for extended periods of timing. If the low voltage battery 110 was to supply the low voltage load 120 for an extended period of time in standby mode it will run the risk of full battery depletion which could prevent operation of some required functions of the vehicle. The low voltage battery 110 cannot be increased in size as eventually the size and weight of the low voltage battery 110 would either effect the performance of the vehicle or simply be too big to be housed within the vehicle. In some cases, the high voltage battery 140 can be used to supply the low voltage load 120 via the DC-DC converter 150. However, the DC-DC converter 150 is sized forthe required loads ofthe normal operating mode of the vehicle and therefore is too large for supplying the low voltage load 120 during standby mode ofthe vehicle. In this scenario, using the high voltage battery 140 and the DC-DC converter 150 to supply the low voltage loads 120 during standby mode ofthe vehicle would be massively inefficient. Therefore, there is a need to provide a power system, and associated control system, which can utilise the high voltage battery 140 to supply low voltage loads 120 with increased efficiency. A control system 200 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 2 and the power systems 300 in accordance with an embodiment of the present invention is described herein with reference to accompanying Figure 3. As shown in Figure 5, the control system 200 or the power system 200 can be installed in a vehicle 500. With reference to Figure 2, there is illustrated a control system 200 for a vehicle 500. The control system 200 comprises one or more controllers 210. The control system 200 is for controlling a power system of a vehicle 500 such as the power system 300 of Figure 3, which is described in detail below. The control system 200 as illustrated in Figure 2 comprises one controller 210, although it will be appreciated that this is merely illustrative. The controller 210 comprises processing means 220 and memory means 230. The processing means 220 may be one or more electronic processing device 220 which operably executes computer-readable instructions. The memory means 230 may be one or more memory devices 230. The memory means 230 is electrically coupled to the processing means 220. The memory means 230 is configured to store instructions, and the processing means 220 is configured to access the memory means 230 and execute the instructions stored thereon. The controller 210 comprises an input means 240 and an output means 250. The input means 240 may comprise an electrical input of the controller 210. The output means 250 may comprise an electrical output of the controller 210. The input means 240 is arranged to receive a first input signal 260 comprising information indicative of an operating state of the vehicle. The operating states of the vehicle may refer to a standby mode and a normal operating mode. The standby mode may be considered as when the vehicle 500 is parked and the vehicle 500 has not been started (e.g., via a key or start button). As described above, standby mode may correspond to a state in which there is no user interaction with the vehicle 500, although it will be appreciated that standby mode may also include some user interaction with the vehicle 500 (e.g., via informatic and / or telematic systems), such as interactions with the vehicle 500 via mobile applications, vehicle status checks, remote unlocking, and other low power operations. As such, standby mode may correspond to an operating state in which the vehicle 500 is parked and the components of the vehicle 500 are receiving zero electrical power and / or electrical power below a predefined threshold. For example, the predefined threshold may be 50W. The normal operating mode may be considered as when the one or more components of the vehicle 500 are receiving electrical power. Optionally, the normal operating mode may correspond to an operating state wherein one or more components of the vehicle 500 are receiving power above the predefined threshold. As another example, standby mode may correspond to an operating state in which the vehicle is parked and only a predefined set of functions are in use, wherein the predefined set of functions require low power loads. In such cases, the normal operating mode may correspond to an operating state in which additional functions are in use, wherein the additional functions require high power loads. Optionally, the first input signal 260 may comprise information indicative of a power supply requirement of a load connected to the low voltage bus. In this respect, the first input signal 260 may be indicative of a request from the low voltage bus for electrical power to supply a low voltage load and / or a low voltage bus and may vary depending on the current operating state of the vehicle 500, e.g. which functions of a vehicle 500 are active and the power requirements of those functions. Similarly, the power supply requirements of the low voltage bus may also vary depending on a charge state of a low voltage battery. Optionally, the low voltage bus load information may include current and / or voltage information. In some cases, the processing means 220 may be configured to determine a power supply requirement of a load connected to the low voltage bus in dependence on the first input signal 260. In this respect, the first input signal 260 may comprise a signal indicative of whether one or more components of the vehicle 500 are receiving electrical power. If first input signal 260 is indicative of a standby mode, the processing means 220 may determine a low power supply requirement, for example, the components of the vehicle 500 are receiving no electrical power and / or electrical power below a predefined threshold. Conversely, if the first input signal is indicative of a normal operating mode the processing means 220 may determine a relatively higher power supply requirement, for example, the components of the vehicle 500 are receiving power above the predefined threshold. Optionally, the input means 240 may further receive second input signal 262, wherein the second input signal 262 is indicative of state of charge information of one or more of a plurality of high voltage battery packs. The state of charge information may indicate a remaining charge of the high voltage battery pack. The state of charge information may further indicate a maximum state of charge of the high voltage battery pack. Additionally, or alternatively, the second input signal 262 may be indicative of state of charge information of the low voltage battery. The state of charge information may indicate a remaining charge of the low voltage battery. The state of charge information may further indicate a maximum state of charge of the low voltage battery. Optionally, the input means 240 may further receive a third input signal 264, wherein the third input signal 264 comprises capability information indicative of an operational capability of the one or more high voltage battery packs and / or the plurality of DC-DC convertors. For example, the capability information may indicate a maximum output of electrical power that the high voltage battery pack and / or DC-DC convertors are capable of outputting. Further, the capability information may indicate preferred operational conditions of the high voltage battery pack and / or DC-DC convertor, such as a preferred output relative to the maximum output. In this example, the preferred operational conditions may correspond to input and / or output conditions of the high voltage battery pack and / or DC-DC convertor in which the high voltage battery pack and / or DC-DC convertor operate more efficiently than compared to outside of the preferred operational conditions. The processing means 220 is configured to receive information indicative of an operating state of the vehicle 500 e.g., from the first input signal 260 connected to the input means 240, and then determine, in dependence on the received operating state of the vehicle 500, a control signal 270 to connect the high voltage to the low voltage bus via one of the first DC-DC converter and the second DC-DC converter. The processing means 220 is then further configured to output the determined control signal 270 via the output means 150 to connect the high voltage battery to the low voltage bus. In some examples, the control signal 270 may further comprise instructions to charge the low voltage battery 310 from the high voltage battery 340 in response to detecting a low state of charge of the low voltage battery 310. This may be achieved by coupling the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 or the second DC-DC converter 360 by closing the associated switch e.g. the first switch (S1) forthe first DC-DC converter 350 orthe second switch (S2) forthe second DC-DC converter. This ensures that the low voltage battery is never ran to complete discharge. Thus, the low voltage battery may still be used for startup operations and the like, when required, e.g., when the vehicle 500 enters the first operating state. Figures 3A-B show a block diagram illustrating a power system 300 according to an embodiment of the present invention. With reference to Figures 3A-B, there is illustrated a power system 300 for a vehicle 500. The power system 300 of Figures 3A-B may operate under the control of the control system 200 of Figure 1, and particularly the control signal 270 of Figure 2 may be output to one or more components of the power system 300 of Figures 3A-b. The power system 300 may further comprise a low voltage ground or low voltage return in some examples. The power system 300 of Figures 3A-B comprises a low voltage bus 330, a high voltage battery 340, a first DC-DC converter 350 and a second DC-DC converter. The power system 300 of Figures 3A-B may also comprise a low voltage battery pack 310, a low voltage load 320, a first switch (S1) and a second switch (S2). It can be seen that the low voltage battery 310 and the low voltage load are connected to the low voltage bus 330. Similarly, the high voltage battery 340 is selectively coupled to the low voltage bus 330 via either the first DC-DC converter 350 orthe second DC-DC converter 360. As shown in Figure 3A, the selective coupling may be achieved by closing the first switch (S1) and opening the second switch (S2) to couple the high voltage battery 340 via the first DC-DC converter 350. Similarly, as shown in Figure 3B, the selective coupling may be achieved by closing the second switch (S2) and opening the fit switch (S1) to couple the high voltage battery 340 via the second DC-DC converter 360. Therefore, based on the operating state of the vehicle 500, the power system 300 will supply power to the low voltage bus 330 from the high voltage battery 340 via the first DC-DC converter 350 or the second DC-DC converter 360. During low load operating conditions e.g. standby mode, the high voltage battery 340 will be coupled to the low voltage bus 330 via the second DC-DC converter 360, as shown in Figure 3B. This is because the second DC-DC converter 360 has a lower power rating then the first DC-DC converter 350 and is therefore more suitable for supplying lower power loads. As such, during higher load operating conditions e.g. normal operating mode, the high voltage battery 340 will be coupled to the low voltage bus 330 via the first DC-DC converter 350, as shown in Figure 3A. In this regard, the first DC-DC converter 350 may be a high power DC-DC converter and the second DC-DC converter 360 may be a low power DC-DC converter. In other words, the first DC-DC converter 350 and second DC-DC converter 360 are configured to, in dependence on receiving the control signal 270, connect the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 or the second DC-DC converter 360, such that the first DC-DC converter 350 or the second DC-DC converter 360 draws electrical power from the high voltage battery 340, converts the electrical power to a lower voltage; and supplies the converted electrical power to the low voltage bus 330 for supplying a low voltage load 320. In doing so, the high voltage battery 340 continues to supply the low voltage loads during standby mode e.g., when the vehicle 500 is in a parked state and the key has not been inserted (i.e., to start the vehicle). This prevents the low voltage battery 310 from being susceptible to full discharge during standby mode, the risk of which is increased with the rising ADAS loads. Moreover, the second DC-DC converter 360 provides more efficient power management at standby modes when supplying relatively low power requirements from the high voltage battery 340. In some examples, the low voltage bus 330 may be a 12V bus and the high voltage battery 340 may be an 800V battery or a set of two 400V batteries. The high voltage battery may comprise a plurality of high voltage battery packs, which may be arranged in series with one another. In some examples, the second DC-DC converter 360 of the power system 300 may be an auxiliary DC-DC converter. In such cases, the auxiliary DC-DC converter may be arranged so that during a first operating state (e.g., normal operating mode) of the vehicle 500 the auxiliary DC-DC converter delivers isolated voltage supplies to one or more components of the first DC-DC converter 350, but during a second operating state (e.g., standby mode) of the vehicle 500 the auxiliary DC-DC converter delivers power from the high voltage battery 340 to the low voltage bus 330 via the closed second switch (S2). As previously mentioned, in some examples the second DC-DC converter 360 may be an auxiliary DC-DC converterthat is electrically integrated within the first DC-DC converter 350. In this regard, the auxiliary DC-DC converter may be a component of the first DC-DC converter 350 such that when it not being used to supply power to the low voltage bus 330, it may provide different isolated voltage levels which act as a power supply to different integrated circuits (IC) of the first DC-DC converter 350. For example, it may supply the isolated voltage levels for high voltage driver input voltages which aid in powering the gate drivers in the first DC-DC converter 350. Further, the auxiliary DC-DC converter, during the first operating state of the vehicle 500, may supply isolated voltage levels to orforthe following components of the first DC-DC converter 350: high voltage drivers, high voltage sensing, safety switches, low voltage drivers, sensing and protection, biasing and DSP etc. It is also worth noting that the auxiliary DC-DC converter may supply isolated voltage levels for the first DC-DC converter 350 between 3.3V and 21V, but may include 3.3V, 5V, 12V, 21V etc. It is worth noting that the auxiliary DC-DC converter may be electrically connected to the first DC-DC converter 350. The auxiliary DC-DC converter may be mounted on the same PCB as the first DC-DC converter 350. In a further example, the second DC-DC converter 360 may be a micro DC-DC converter which may be arranged to only supply electrical power to the low voltage bus 330 via the second switch (S2) in accordance with the disclosure of the present invention. As such, the micro DC-DC converter may be bespoke made for the purpose of supplying power to the low voltage bus 330 from the high voltage battery and thereby may be more efficient at supplying power to the low voltage bus 330 from the high voltage battery 340. The micro DC-DC converter may supply converted electrical power from the high voltage battery 340 in the range of 20Wto 80W, or optionally the micro DC-DC converter may supply converted electrical power from the high voltage battery 340 in the range of 40W to 50W. In contrast, the first DC-DC converter 350 may supply converted electrical power of greater than 1.5kW from the high voltage battery 340 to the low voltage bus 330, or optionally the first DC-DC converter 350 may supply converted electrical power of greater than 2kW. It is worth noting that the micro DC-DC converter may be mounted on the same PCB as the first DC-DC converter 350. In an example, the second DC-DC converter 360 may be configured to further supply converted electrical power from the high voltage battery 340 to the low voltage battery 310 via the low voltage bus 330 during the second operating state of the vehicle 500. This may be done to maintain the state of charge of the low voltage battery 310. This ensures that the low voltage battery is never ran to complete discharge. Thus, the low voltage battery may still be used for startup operations and the like, when required, e.g., when the vehicle 500 enters the first operating state. The above may be implemented by detecting a low state of charge of the low voltage battery 310. This may be detected via the second input signal 262 as discussed previously. In response, the control signal 270 may cause the first DC-DC converter 350 or the second DC-DC converter 360 to charge the low voltage battery 310. This may be achieved by coupling the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 or the second DC-DC converter 360 by closing the associated switch e.g. the first switch (S1) for the first DC-DC converter 350 or the second switch (S2) for the second DC-DC converter. Figure 4 shows a flow chart showing a method 400 according to an embodiment of the present invention. The method 400 of Figure 4 may be implemented by the control system 200 of Figure 2 and / or the power system 300 of Figure 3. The method 400 of Figure 4 may be stored on computer readable storage medium, or as computer readable instructions. The method 400 of Figure 3 includes, at 410, receiving information indicative of an operating state of the vehicle 500. As discussed above, the received information indicative of an operating state may indicate that the vehicle 500 is in standby mode or in normal operating mode. For example, the received information indicative of an operating state may indicate that the vehicle 500 is parked and one or more components of the vehicle are receiving zero electrical power and / or electrical power below a predefined threshold (standby mode) or that one or more components of the vehicle 500 are receiving electrical power above the predefined threshold (normal operating mode). The received information may also indicate the power supply requirement of the low voltage bus 330, and may comprise voltage and / or current information of a low voltage load 320 required by the low voltage bus 330. The method 400 of Figure 4 further includes, at 420, determining, in dependence of the received operating state, a control signal to connect the high voltage battery 340 to the low voltage bus 330 via one of the first DC-DC converter 350 and the second DC-DC converter 360. The control signal may include instructions to open or close switches that connect the first DC-DC converter 350 and the second DC-DC converter 360 to the low voltage bus 330. In some examples, determining the control signal may also comprise determining a power requirement of a load connected to the low voltage bus 330 in dependence on the received operating state of the vehicle 500. In this regard, the connected load may be the low voltage load 320. The dependence on the received operating state of the vehicle 500 will have an effect on the power requirement as the power requirement will be higher in the normal operating mode of the vehicle 500 compared to the standby mode of the vehicle 500. The control signal 270 may comprise further instructions to connect, in dependence of the received operating state, the high voltage battery 340 to the low volage bus 330 via the first DC-DC converter 350 during periods of high power loads on the low voltage bus 330 or to connect, in dependence of the received operating state, the high voltage battery 340 to the low voltage bus 330 via the second DC-DC converter 360 during periods of low power loads on the low voltage bus 330. In other words, the control signal may connect the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 when the vehicle 500 is in a normal operating mode and connect the high voltage battery 340 to the low voltage bus 330 via the second DC-DC converter 360 when the vehicle 500 is in a standby operating state. Further, the control signal may comprise instructions to connect the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 during a first operating state and connect the high voltage battery 340 to the low voltage bus 330 via the second DC-DC converter 360 during a second operating state. The first operating state may refer to an operating state corresponding to higher power loads or normal operating mode of the vehicle 500 whereas the second operation state may refer to an operating state corresponding to lower power loads or standby mode of the vehicle 500. Higher power loads may refer to loads that are greater than 50W and lower power loads may refer to loads that are less than 50W. To facilitate the above, the control signal may comprise instructions such that during the first operating state of the vehicle 500, the instructions may close a first switch (S1), the first switch being a switch that couples the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 and open a second switch (S2), the second switch being a switch that couples the high voltage battery 340 to the low voltage bus 330 via the second DC-DC converter 360. On the contrary, the control signal may comprise instructions such that during the second operating state of the vehicle 500, the instructions may open a first switch (S1), the first switch being a switch that couples the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350; and close the second switch (S2), the second switch being a switch that couples the high voltage battery 340 to the low voltage bus 330 via the second DC-DC converter 360. The method 400 comprises, at 430, outputting the determined control signal to connect the high voltage battery 340 to the low voltage bus 330. Outputting the determined control signal may connect the high voltage battery 340 to the low voltage bus 330 via the first DC-DC converter 350 or the second DC-DC converter 360, such that the first DC-DC converter 350 or the second DC-DC converter 360 draws electrical power from the high voltage battery 330, converts the electrical power to a lower voltage; and supplies the converted electrical power to the low voltage bus 330 for supplying a low voltage load 320. Optionally, the method 400 may comprise a further step relating to determining the state of charge of the low voltage battery 310. In this respect, the state of charge of the low voltage battery 310 may be supplied by the second input signal 262. In response to detecting a low state of charge of the low voltage battery, the control signal 270 may be configured to cause the first DC-DC converter or the second DC-DC converter to charge the low voltage battery. As such, the second DC-DC converter may further supply converted electrical power to a low voltage battery during the second operating state of the vehicle to maintain the state of charge of the low voltage battery, the low voltage battery being connected to the low voltage bus. Figure 5 shows a vehicle 500 in accordance with an embodiment of the invention. The vehicle 500 may include the control system 200 of Figure 2 and the power system 300 of Figure 3. Whilst the control system 200 and power system 300 are shown as separate units, it will be appreciated that this is illustrative and that the control system 200 and power system 300 may be integrated as a single unit. For example, the power system 300 may comprise the control system 200. As described above, the vehicle 500 may be an electric vehicle such as a battery electric vehicle (BEV) or a hybrid vehicle such as a mild-hybrid electric vehicle (MHEV) or plug-in-hybrid electric vehicle (PHEV). Vehicle 500 may also be an EGO vehicle, i.e., a vehicle that is equipped with autonomous or semi-autonomous driving 5 technology and is capable of sensing and navigating its environment without direct input from a human driver. 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. 10

Claims

1. A control system for controlling a power system of a vehicle , the power system comprising a high voltage battery , a first DC-DC converter and a second DC-DC converter, the high voltage battery being selectively connected to a low voltage bus via the first DC-DC converter or the second DC-DC converter, the control system comprising one or more processors collectively configured to:receive information indicative of an operating state of the vehicle ;determine, in dependence of the received operating state, a control signal to connect the high voltage battery to the low voltage bus via one of the first DC-DC converter and the second DC-DC converter; andoutput the determined control signal to connect the high voltage battery to the low voltage bus .

2. The control system of claim 1, wherein determining the control signal further comprises determining a power requirement of a load connected to the low voltage bus in dependence on the received operating state.

3. The control system of any preceding claim, wherein the first DC-DC converter is a high power DC-DC converter and the second DC-DC converter is a low power DC-DC converter.

4. The control system of any preceding claim, wherein the control signal comprises further instructions to: connect, in dependence of the received operating state, the high voltage battery to the low voltage bus via the first DC-DC converter during periods of high power loads on the low voltage bus , or to connect, in dependence of the received operating state, the high voltage battery to the low voltage bus via the second DC-DC converter during periods of low power loads on the low voltage bus .

5. The control system of any preceding claim, wherein the control signal comprises instructions to: connect the high voltage battery to the low voltage bus via the first DC-DC converter during a first operating state and connect the high voltage battery to the low voltage bus via the second DC-DC converter during a second operating state.

6. The control system of claim 5, wherein, during the first operating state of the vehicle , the control signal comprises instructions to:close a first switch , the first switch being a switch that couples the high voltage battery to the low voltage bus via the first DC-DC converter; andopen a second switch, the second switch being a switch that couples the high voltage battery to the low voltage bus via the second DC-DC converter.

7. The control system of claim 5 or 6, wherein, during the second operating state of the vehicle , the control signal comprises instructions to:open a first switch , the first switch being a switch that couples the high voltage battery to the low voltage bus via the first DC-DC converter; andclose the second switch, the second switch being a switch that couples the high voltage battery to the low voltage bus via the second DC-DC converter.

8. The control system of any of claims 5 to 7, wherein the first operating state of the vehicle is a state wherein one or more components of the vehicle are receiving electrical power above a predefined threshold.

9. The control system of claim 8, wherein the second operating state of the vehicle is a state wherein the vehicle is parked, and wherein the one or more components of the vehicle are receiving zero electrical power and / or electrical power below the predefined threshold.

10. The control system of any claim 5 to 9, wherein the second DC-DC converter further supplies converted electrical power to a low voltage battery during the second operating state of the vehicle to maintain the state of charge of the low voltage battery , the low voltage battery being connected to the low voltage bus.

11. A power system of a vehicle , the power system comprising the control system of any preceding claim, and further comprising:the high voltage battery ;the first DC-DC converter;the second DC-DC converter;the low voltage bus ; andthe first DC-DC converter and second DC-DC converter being configured to, in dependence on receiving the control signal, connecting the high voltage battery to the low voltage bus via the first DC-DC converter or the second DC-DC converter, such that the first DC-DC converter or the second DC-DC converter draws electrical power from the high voltage battery , converts the electrical power to a lower voltage; and supplies the converted electrical power to the low voltage bus for supplying a low voltage load.

12. The power system of claim 11, wherein the second DC-DC converter is an auxiliary DC-DC converter, the second DC-DC converter being arranged such that, during a first operating state of the vehicle, the second DC-DC converter delivers isolated voltage supplies to one or more components of the first DC-DC converter.

13. The power system of claim 11, wherein the second DC-DC converter is a micro DC-DC converter, the second DC-DC converter being arranged to only supply electrical power to the low voltage bus of the vehicle.

14. A vehicle comprising the control system of any of claims 1 to 10 or the power system of any of claims 11 to 13.5 15. A method for operating a control system for controlling a power system of a vehicle , the powersystem comprising a high voltage battery , a first DC-DC converter and a second DC-DC converter, the high voltage battery being selectively connected to a low voltage bus via the first DC-DC converter or the second DC-DC converter, the method comprising:receiving information indicative of an operating state of the vehicle ;10 determining, in dependence of the received operating state, a control signal to connect thehigh voltage battery to the low voltage bus via one of the first DC-DC converter and the second DC-DC converter; andoutputting the determined control signal to connect the high voltage battery to the low voltage bus.15

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