System for controlling the connection configuration of a battery system

Abstract

A system for controlling the configuration of a vehicle battery system 210 controllable between a first configuration in which a plurality of batteries 211, 212 are connected in series, and a second c

Description

TECHNICAL FIELD The present disclosure relates to a system for controlling the connection configuration of a battery system of a vehicle. Aspects of the invention relate to a system for controlling the connection configuration of a battery system of a vehicle, to a battery system of a vehicle, and to a vehicle comprising such systems. 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 system for controlling the connection configuration of a battery system of a vehicle, a battery system of a vehicle, and a vehicle comprising such systems as claimed in the appended claims. According to an aspect of the present invention there is provided a system for controlling the connection configuration of a battery system of a vehicle, wherein the battery system is switchable between a first voltage configuration in which a plurality of batteries are connected in series, and a second voltage configuration in which the plurality of batteries are connected in parallel, the system comprising: a switching arrangement controllable between a first configuration in which the plurality of batteries are connected in series and a second configuration in which the plurality of batteries are connected in parallel, wherein: in the first configuration one or more first configuration switch is in a closed state and one or more second configuration switch is in an open state; and in the second configuration the one or more first configuration switch is in an open state and the one or more second configuration switch is in a closed state; and a first control switch configured to control the one or more first configuration switch; and a second control switch configured to control the one or more second configuration switch. Wherein, optionally, the first and second control switches are configured to receive a control signal, and: the first control switch is configured to control the one or more first configuration switch to be in the closed state when the control signal comprises a voltage at or above a first threshold voltage and to control the one or more first configuration switch to be in the open state when the control signal comprises a voltage below a second threshold voltage; and the second control switch is configured to control the one or more second configuration switch to be in the open state when the control signal comprises a voltage at or above the first threshold voltage and to control the one or more second configuration switch to be in the closed state when the control signal comprises a voltage below the second threshold voltage. The present invention is advantageous as the control switches can be used to control the configuration of the configuration switches, thereby controlling the configuration of the battery system. By configuring the control switches to operate in opposite senses, a single control voltage line can be used to ensure that the battery system cannot be connected in series and parallel at the same time. The first threshold voltage and the second threshold voltage may be the same. For example, the first control switch may be configured to control the one or more first configuration switch to be in the closed state when the control signal comprises a voltage at or above 5 volts, and to control the one or more first configuration switch to be in the open state when the control signal comprises a voltage below 5volts; and the second control switch may be configured to control the one or more second configuration switch to be in the open state when the control signal comprises a voltage at or above 5 volts, and to control the one or more second configuration switch to be in the closed state when the control signal comprises a voltage below 5 volts. It will be understood that the 5 volt example is illustrative only and that any suitable voltage may be used. The control signal comprising a voltage at or above the first threshold voltage optionally corresponds to a logical one, and the control signal comprising a voltage below the second threshold voltage optionally corresponds to a logical zero. This allows the configuration of the battery system to be controlled by a standard commercially available controller. The system may comprise a controller configured to output a control signal comprising: a voltage at or above the first threshold voltage; or a voltage below the second threshold voltage. In one example, the first control switch and / or the second control switch may comprise a transistor. Optionally the first control switch may comprise one of an n-type or a p-type metal-oxide-semiconductor field effect transistor (MOSFET), and the second control switch may comprise the other of an n-type or a p-type MOSFET to facilitate control of the configuration switches in opposite senses. The MOSFETs may each optionally comprise an enhancement type MOSFET, or the MOSFETs may each optionally comprise a depletion type MOSFET. According to another aspect of the present invention there is provided a battery system of a vehicle comprising the system described above and a plurality of batteries. According to a further aspect of the present invention there is provided a vehicle comprising the system as described above or the battery system as 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 a schematic view of a vehicle power supply system comprising a battery system; and Figure 3 shows a schematic diagram of a system for controlling the connection configuration of the battery system of Figure 2. 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 system 110 for controlling the connection configuration of a battery system 210 (see Figure 2) 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 battery system 210, a load bus 220, and an on-board charger (OBC) 230. 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 system 210 comprises first and second batteries 211,212 which may be connected in series by closure of first configuration switch 213, or in parallel by closure of second configuration switches 214, 215. The configuration switches 213, 214, 215 together for a switching arrangement 205. In Figure 2, the first configuration switch 213 is shown as closed for illustrative purposes. When the first configuration switch 213 is closed, second configuration switches 214, 215 are open to prevent the batteries being connected in series and in parallel at the same time. Similarly, when second configuration switches 214, 215 are closed, the first configuration switch 213 is open. The battery system 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 fora flexible system capable of operating with different voltage requirements. The load bus 220 can be directly connected to the battery system 210 by closing load bus switches 216, 217. When the load bus switches 216, 217 are closed and the battery system 210 is configured with the batteries 211, 212 connected in series, the battery system 210 provides a high-voltage, i.e. substantially 800V, supply to the load bus 220. The load bus 220 comprises circuitry which connects the battery system 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 system 210. Accordingly, when the vehicle power system 200 is connected to an external DC power supply via the firstand second inlet portions 226,227, and the battery system 210 is arranged in the series connection configuration with first configuration switch 213 closed and second configuration 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 OBC 230 to the battery system 210. Accordingly, when the vehicle power system 200 is connected to an external AC power supply, and the battery system 210 is arranged in the parallel connection configuration with first configuration switch 213 open and second configuration switches 214, 215 closed, the batteries 211,212 are able to be charged by power provided by the AC level 1 or level 2 EV charger. It is not possible to drive the vehicle 100 when the battery system 210 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 system 210 is arranged in the low-voltage parallel connection configuration to enable the battery system 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. The first configuration switch 213 and the second configuration switches 214, 215 are electrically operated switches which require an electrical power supply in order to operate. The configuration switches 213, 214, 215 are arranged so that they default to an open condition when no power is supplied. In the present embodiment, the configuration switches 213, 214, 215 are electromagnetic switches which close when an electric current is supplied to the switch, and open when there is no electric current supplied to the switch. Figure 3 shows a schematic diagram of the system 110 for controlling the connection configuration of the battery system 210. The system 110 comprises a controller 115 which is configured to output a control signal on a control line 116. The controller 115 receives power from a power supply line 114 which is connected to the bi-directional DCDC converter 223 and the nominal 12V battery 224 via an n-type MOSFET 112. The control pin 111 of the n-type MOSFET 112 is connected to a separate control voltage by a control line (not shown). The n-type MOSFET 112 acts as a switch to control power supply to the controller 115 and to a power supply line 117. The control line 116 is connected to the control pin 121 of an n-type MOSFET 120 and to the control pin 123 of a p-type MOSFET 122. The n-type MOSFET 120 forms a first control switch located between the first configuration switch 213 and the power supply line 117. Similarly, the p-type MOSFET 122 forms a second control switch located between the second configuration switches 214, 215 and the power supply line 117. In use, when it is desired to configure the battery system 210 in the series configuration, the controller 115 outputs a control voltage onto the control line 116. The control voltage has a value at or above a first threshold voltage (for example 5 volts) at which the n-type MOSFET is configured to ‘turn on’. Consequently, the n-type MOSFET becomes conductive and connects the first configuration switch 213 to the power supply line 117 thereby causing the first configuration switch 213 to close. In contrast to this, the p-type MOSFET is configured to ‘turn on’ only when the control voltage has a value below a second threshold voltage (for example 5 volts). Consequently, the p-type MOSFET does not connect the second configuration switches 214, 215 to the power supply line 117 so that the second configuration switches 214, 215 do not close. When it is desired to configure the battery system 210 in the parallel configuration, the controller 115 outputs a control voltage onto the control line 116 which is below the first threshold voltage at which the n-type MOSFET is configured to ‘turn on’. Consequently, the n-type MOSFET does not ‘turn on’ to connect the first configuration switch 213 to the power supply line 117. The first configuration switch 213 therefore does not close, or opens if already closed. By contrast, the p-type MOSFET ‘turns on’ when the control voltage is below the second threshold voltage and so connects the second configuration switches 214, 215 to the power supply line 117 so that the second configuration switches 214, 215 close. The threshold voltage at which the n-type MOSFET is configured to ‘turn on’ is typically 5 volts. However, any suitable voltage threshold may be used. A control voltage at or above the first threshold voltage corresponds to a logical ‘one’ and a control voltage below the second threshold voltage corresponds to a logical ‘zero’. In the example described above, the first threshold voltage and the second threshold voltage are the same. It will be clear to a person skilled in the art that the controller 115 may be configured to output different control voltages on the control line 116. For example the controller may output a voltage which is nominally, but not exactly 5 volts (for example 4.5 volts), and my output a voltage which is nominally, but not exactly 0 volts (for example 0.5 volts), In this example, the first threshold voltage is 4.5 volts and the second threshold voltage is 0.5 volts. It will be clear to a person skilled in the art that the arrangement described in relation to Figure 3 can be modified such that the first configuration switch is controlled by a p-type MOSFET and the second configuration switches are controlled by an n-type MOSFET. In this case, when it is desired to configure the battery system 5 210 in the series configuration, the controller 115 outputs a control voltage onto the control line 116 having a value below second threshold voltage, and when it is desired to configure the battery system 210 in the parallel configuration, the controller 115 outputs a control voltage onto the control line 116 having a value at or above the second threshold value. 10 The MOSFETs 120,122 shown in Figure 3 are enhancement type MOSFETs. It will be understood by a person skilled in the art that depletion type MOSFETs could be used as an alternative, in which case the controller 115 would be configured to function in the opposite sense to that described above. It will be appreciated that various changes and modifications can be made to the present invention without 15 departing from the scope of the present application.

Claims

1. A system for controlling the connection configuration of a battery system of a vehicle, wherein the battery system is switchable between a first voltage configuration in which a plurality of batteries are connected in series, and a second voltage configuration in which the plurality of batteries are connected in parallel, the system comprising:a switching arrangement controllable between a first configuration in which the plurality of batteries are connected in series and a second configuration in which the plurality of batteries are connected in parallel, wherein:in the first configuration one or more first configuration switch is in a closed state and one or more second configuration switch is in an open state; andin the second configuration the one or more first configuration switch is in an open state and the one or more second configuration switch is in a closed state;anda first control switch configured to control the one or more first configuration switch; anda second control switch configured to control the one or more second configuration switch, wherein the first and second control switches are configured to receive a control signal, and:the first control switch is configured to control the one or more first configuration switch to be in the closed state when the control signal comprises a voltage at or above a first threshold voltage and to control the one or more first configuration switch to be in the open state when the control signal comprises a voltage below a second threshold voltage; andthe second control switch is configured to control the one or more second configuration switch to be in the open state when the control signal comprises a voltage at or above the first threshold voltage and to control the one or more second configuration switch to be in the closed state when the control signal comprises a voltage below the second threshold voltage.

2. The system of claim 1, wherein the control signal comprising a voltage at or above the first threshold voltage corresponds to a logical one, and the control signal comprising a voltage below the second threshold voltage corresponds to a logical zero.

3. The system of claim 1 or 2, comprising a controller configured to output the control signal comprising:a voltage at or above the first threshold voltage; or a voltage below the second threshold voltage.

4. The system of any preceding claim, wherein the first control switch and / or the second control switch comprises a transistor.

5. The system of claim 4, wherein the first control switch comprises one of an n-type or a p-type metal-oxide-semiconductor field effect transistor, and the second control switch comprises the other of an n-type or a p-type MOSFET.

6. The system of claim 5, wherein each MOSFET is an enhancement type MOSFET.

7. A battery system of a vehicle comprising the system of any one of claims 1 to 6 and a plurality ofbatteries.

58. A vehicle comprising the system of any one of claims 1 to 6 or the battery system of claim 7.10

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