Patent Description:
In recent years, vehicles have been developed using electric power as a source of motion. An electric vehicle is an automobile that is powered by an electric motor using energy stored in rechargeable batteries. An electric vehicle may be solely powered by batteries or may be a form of hybrid vehicle powered by for example a gasoline generator. Furthermore, the vehicle may include a combination of electric motor and conventional combustion engine. In general, an electric-vehicle battery (EVB) or traction battery is a battery used to power the propulsion of battery electric vehicles (BEVs). Electric-vehicle batteries differ from starting, lighting, and ignition batteries because they are designed to give power over sustained periods of time. A rechargeable or secondary battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter provides only an irreversible conversion of chemical to electrical energy. Low-capacity rechargeable batteries are used as power supply for small electronic devices, such as cellular phones, notebook computers and camcorders, while high-capacity rechargeable batteries are used as the power supply for hybrid vehicles and the like. Rechargeable batteries may be used as a battery module formed of a plurality of unit battery cells coupled in series and/or in parallel so as to provide a high energy density, in particular for motor driving of a hybrid vehicle. A battery module may be formed by interconnecting the electrode terminals of the plurality of unit battery cells depending on a required amount of power and in order to realize a high-power rechargeable battery. The cells can be connected in series, parallel or in a mixture of both to deliver the desired voltage, capacity, or power density. Components of battery packs include the individual battery modules and the interconnects, which provide electrical conductivity between them.

For meeting the dynamic power demands of various electrical consumers connected to the battery system a static control of battery power output and charging is not sufficient. Thus, steady exchange of information between the battery system and the controllers of the electrical consumers is required. This information includes the battery systems actual state of charge, potential electrical performance, charging ability and internal resistance as well as actual or predicted power demands or surpluses of the consumers.

Battery systems usually comprise a battery control for processing the aforementioned information. The battery control may comprise controllers of the various electrical consumers and contain suitable internal communication busses, e.g. a SPI or CAN interface. The battery control may further communicate with battery submodules, for example with cell supervision circuits or cell connection and sensing units. Thus, the battery control may be provided for managing the battery stack, such as by protecting the battery from operating outside its safe operating area, monitoring its state, calculating secondary data, reporting that data, controlling its environment, authenticating it and/or balancing it. Typically, the battery control may control a power switch to a load and may switch the load in various fault situations.

The <CIT> discloses a multiple battery charging and discharging system which controls the configuration of multiple batteries arranged in multiple battery banks. The <CIT> discloses a technique for detecting an offset error of a current. The <CIT> discloses a vertical bus circuit which includes multiple devices for transmitting signals between the bus devices. The <CIT> discloses a power unit for an electric vehicle which includes a first power source and a second power source to supply power to a load. The <CIT> teaches a battery system with two types of batteries which are used for providing power to various power consumers of the vehicle.

In a cold crank case the power supply for various electronic units of a battery system may provide not sufficient power in a transient time regime. A board net voltage may for example drop down to about <NUM> V (Volts) during cold crank which is not enough for several electronic units.

Current solutions of the prior art use boost converters to support cold crank functionality. For example, boost converters may boost dropped supply voltages from <NUM> V up to <NUM> V to keep power consuming electronic units supplied.

However, boost converters are costly. For the boosting functionality at least inductors, caps, diodes, a MOSFETs and shunts are required. Furthermore, the circuitry has to provide electronic units and power switches, e.g. relays, which means that output power of several watts are needed. For boosting a voltage from <NUM> V currents of around <NUM> A have to be provided.

It is thus an object of the present invention to overcome or reduce at least some of the drawbacks of the prior art. In particular it is an object to provide a power supply system for providing power to components of a battery system whose electrical components are supported with persistent and sufficient power in cold crank conditions thereby circumventing the requirement of a boost converter.

Embodiments of the present disclosure seek to solve at least one of the problems existing in the prior art to at least some extent.

A power supply system for cold crank functionality for providing power to components of a battery system of a vehicle is provided according to claim <NUM>.

A cold crank mode means that the supply voltage of the first power supply has dropped below the threshold voltage due to cold crank. The normal mode is referred to the case, where the supply voltage of the first power supply is above the threshold voltage. The electronic unit may be, expressed in other words, a power consuming electronic unit or a power consuming electronic component of a battery system. In a battery system several electronic units need to be supplied with a sufficient power. The electronic unit is a microprocessor. The microprocessor requires for example a supply voltage of <NUM> V. In the cold crank mode or cold crank case, the first power supply can drop below this required supply voltage, for example down to <NUM> V for a time window of typically about <NUM>-<NUM>. The power switch is a relay. The power switch, i.e. the relay, may be still controllable with a supply voltage of <NUM> V or even below <NUM> V. For example, present relay control units and/or relays may require <NUM> V nominally. Therefore, the power supply system has the advantage that the power switch unit according to the present invention can still be controlled by the first power supply even in the cold crank mode. The electronic unit as separate unit to the switch control unit is electrically connected to the second power supply to be powered in the cold crank mode or cold crank case. First and second power supply may be independent and/or separated from each other. The second power supply may then be not affected during cold crank. The present invention has the advantage that a second power supply can take over the power supply of the electronic unit or electronic units, when the first power supply unit drops below the voltage threshold. The switching unit may be positioned separately from the electronic unit, but the invention is not restricted thereto and the switching unit may also be integrated in the electronic unit itself. Electrically disconnect may mean that the corresponding power supply cannot supply any power to the electronic unit. Electrically connect may mean that the corresponding power supply can supply power to the electronic unit. With the second power supply, which supplies in the cold crank time window, the use of a boost converter is avoided and a persistent power supply also in a cold crank case is provided.

In a preferred embodiment, the first power supply may be a board net voltage of a vehicle and/or the second power supply may be a battery cell stack comprising a plurality of battery cells. The board net voltage may preferably be a <NUM> V board net which is the conventional supply board net in an electric vehicle. The <NUM> V board net may be provided by a <NUM> V battery, e.g. a lead acid battery or a Nickel-Cadmium battery, but the invention is not restricted thereto. The second power supply may preferably be the system voltage of the battery cell stack, which provides preferably <NUM> V, but the invention is not restricted thereto. The <NUM> V output may be provided by a stack of <NUM> battery cells each with a nominal output voltage of <NUM> V, but the invention is also not restricted thereto. In other embodiments, the second power supply may be an intermediate output voltage from a sub stack of the above described battery stack providing <NUM>*n V, where n is the number of battery cells of the sub stack.

Preferably, the threshold voltage may be between <NUM> and <NUM> V, preferably between <NUM> and <NUM> V, more preferably between <NUM> and <NUM> V. These thresholds guarantee that the power supply does not drop below <NUM> V, which for many electronic units, e.g. the microprocessor or CAN transceiver, is the required supply voltage. Therefore, as soon as this threshold is met by the first power supply, the second power supply is electrically connected to the electronic unit such that sufficient power supply is still available.

In a preferred embodiment, the switching unit may be configured to electrically connect the first power supply to the electronic unit and electrically disconnect the second power supply from the electronic unit, when the voltage of the first power supply rises above the threshold voltage. Thereby, the second power supply is advantageously loaded only for the minimum amount of time necessary. Often, the voltage drop of the first power supply may last usually only for several ms, mostly <NUM>-<NUM>, such that after this time interval the first power supply may then fulfill its role as main power supplier.

Preferably, the switching unit may comprise a first input electrically connected to the first power supply, a second input electrically connected to the second power supply and an output electrically connected to the electronic unit. The switching unit is thereby a separate unit, receiving both voltages from both power supplies.

In a preferred embodiment, the switching unit may comprise a first diode, a second diode and an output node, wherein the first power supply is electrically connected to the anode of the first diode, the second power supply is electrically connected to the anode of the second diode and the output node is electrically connected to the cathode of the first and second diode, and wherein the output node is further electrically connected to the electronic unit. A diode is, as commonly known, an electronic element which conducts current primarily in one direction. It thus may have low resistance when forward biased and high resistance when reverse biased. The advantage here is that this selecting unit works fully automatic. The connected diodes select or set the higher voltage of the two power supplies conductive and disconnect or set the lower voltage non-conductive. The switching is thus dependent on the voltages applied to the respective diodes. In particular, the voltage applied to the anode of the second diode coincides with the threshold voltage. A voltage below <NUM> V at the anode of the first diode will set the first diode non-conductive, thus effectively disconnecting the first power supply, while the second diode is set conductive or is in other words forward biased, thus effectively connecting the second power supply.

Preferably, at least the second diode may be a low drop-out diode. Low drop-out diodes are also referred to as active diodes. These diodes have a reduced inner voltage drop. Thus, voltage losses are reduced or even eliminated. When the voltage input to the anode is 5V, this is then advantageously also the 5V that will supplied to the electronic unit.

In a preferred embodiment, the second power supply is a battery cell stack comprising a plurality of battery cells between a first node and second node, the second node being on a higher electrical potential than the first node and electrically connected to the second input of the switching unit. The first and the second nodes are preferably at the ends of the battery cell stack, but the invention is not restricted thereto. Preferably, the first node is set to ground potential.

Preferably, the power supply system may comprise a voltage regulator electrically interconnected between the second node of the battery cell stack and the second input of the switching unit, wherein the voltage regulator is configured to reduce the input voltage received from the second node to an output voltage supplied to the switching unit which is lower than the input voltage. In preferred cases, the voltage on the second node is <NUM> V. This voltage is in generally too high for supplying the electronic units. In particular, for using the automatic diodes for switching the power supplies, the voltage has to be reduced from <NUM> V to, e.g., preferably <NUM> V by the additional voltage regulator. The voltage regulator requires substantially less components than a boost converter.

In a preferred embodiment, the power supply system may comprise an analog front end chip, AFE, which is electrically connected to the first node and the second node of the battery cell stack to receive the voltage in between, further comprising an internal voltage regulator configured to reduce the received voltage to an output voltage lower than the input voltage, and wherein the AFE is configured supply the output voltage to an output electrically connected to the second input of the switching unit. The analog front end chip, AFE, may be in general suitable to measure several quantities along the battery stack. That includes for example the charging/discharging current, the temperature, voltages and cell voltages. In here, the AFE chip may receive the voltage difference between first and second node. Due to the presence of an internal voltage regulator, the advantage is that this voltage can be internally be transformed into a lower voltage suitable for supply to the electronic unit during cold crank conditions. In this embodiment, advantageously, a separate voltage regulator is not needed.

Preferably, the voltage regulator and/or the internal voltage regulator may be a low-dropout regulator and/or wherein at least one of the voltage regulators may be configured to output a voltage of at least 5V. These regulators are preferably transistor-Zener-diode regulators, e.g. comprising resistors, transistors and Zener-diode, but the invention is not restricted thereto and also other voltage regulator implementations may be used.

In a preferred embodiment, a power supply regulator may be interconnected between the switching unit and the electronic unit, the power supply regulator configured to regulate the received voltage to a supply voltage required by the electronic unit. Thereby, individual voltages can be adapted and varied for the corresponding electronic units.

Preferably, the electronic unit is a microprocessor. The microprocessor may be the main electronic unit in the power supply system for safety purposes, e.g. controlling the power switch, and thus has to be persistently supplied. Therefore, in cold crank conditions, the microprocessor should not be unavailable in that time. Therefore, the present invention guarantees a persistent supply of the microprocessor due to the second power supply.

In a preferred embodiment, the microprocessor may be configured to switch into a low power consumption mode, when the microprocessor detects that the supplied power has dropped below a threshold power. Such low power consumption mode may also be referred to as a sleeping mode. Since the power supplies, in particular from the AFE, may support smaller currents, e.g. <NUM> to <NUM> mA, a low power consumption mode may be suitable to match the reduced power provided. Thus, the microprocessor may be configured to change to a low power consumption mode. In this low power consumption mode the microprocessor may be capable of performing core functions, for example security relevant functions, which may be to control the power switch and initiate a switch off in a fault state.

In another aspect, a battery system with a power supply system according to any of the embodiments as described above is disclosed.

In another aspect, a vehicle is disclosed including a power supply system according any of the embodiments as described above.

Further aspects of the present invention could be learned from the dependent claims or the following description.

Effects and features of the exemplary embodiments, and implementation methods thereof will be described with reference to the accompanying drawings. In the drawings, like reference numerals denote like elements, and redundant descriptions are omitted. Further, the use of "may" when describing embodiments of the present invention refers to "one or more embodiments of the present invention.

In the following description of embodiments of the present invention, the terms of a singular form may include plural forms unless the context clearly indicates otherwise.

Expressions as "connected to" or "coupled to" to another entity it can be directly connected to or coupled to or one or more elements may be present. It will be further understood that the terms "comprises," "comprising," "includes," and "including," when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

<FIG> discloses a power supply system <NUM> for cold crank functionality for a battery system of a vehicle according to a first embodiment of the invention. The power supply system <NUM> comprises a switch control unit <NUM> for controlling a power switch <NUM> to switch an external load, the latter not shown here. The power switch <NUM> is a relay and the switch control unit <NUM> is a relay control unit.

The power supply system <NUM> further comprises an electronic unit <NUM>. As depicted in <FIG>, the electronic unit <NUM> is a microprocessor <NUM>.

A first power supply <NUM> is electrically connected to the switch control unit <NUM>. Therefore, a node <NUM> is comprised to which the voltage is supplied to by the first power supply <NUM>, wherein the node <NUM> is electrically connected to an input of the switch control unit <NUM>. Thereby, the first power supply <NUM> is configured to supply the switch control unit <NUM> with electric power. The node <NUM> and the line connected to the node may be on high potential provided by the first power supply <NUM>, while the other line may be grounded, see the lower line in <FIG>.

The first power supply <NUM> further is electrically connected to the electronic unit <NUM> in a normal mode and is thereby configured to electrically supply the electronic unit <NUM> with power in a normal mode.

The power supply system <NUM> comprises further a second power supply <NUM>. The second power supply <NUM> may preferably be a battery cell stack <NUM> generating a system voltage VDD at the ends of the battery cell stack <NUM>, as it can be seen in the example embodiments in <FIG>, which provides preferably <NUM> V, but the invention is not restricted thereto. As an example, the <NUM> V output may be provided by a stack of <NUM> battery cells each with a nominal output voltage of <NUM> V, but this is merely an example. The second power supply <NUM> may be for example an intermediate output voltage from a sub stack of the above described battery cell stack <NUM>.

Further, the power supply system <NUM> comprises a switching unit <NUM>. The switching unit <NUM> is configured to electrically disconnect the first power supply <NUM> from the electronic unit <NUM> in a cold crank mode. A cold crank mode occurs when the supply voltage of the first power supply <NUM> drops or is below a threshold voltage. Usually, such a voltage drop occurs for a short time window of about <NUM>-<NUM>. Further the switching unit <NUM> is configured to connect the second power supply <NUM> to the electronic unit <NUM>, such that the second power supply <NUM> supplies the electronic unit <NUM> in the cold crank mode. Thereby, the supply of the electronic unit <NUM>, that is the microprocessor <NUM>, is guaranteed throughout the transient time window of cold crank. In here, as can be seen in <FIG>, the first power supply <NUM> remains electrically connected to the switch control unit <NUM> to supply power to the switch control <NUM> also in the cold crank mode. That is, the node <NUM> is interconnected between switching unit <NUM> and the first power supply <NUM>.

The first power supply <NUM> may preferably be a board net voltage of a vehicle. The board net voltage, as shown in this example embodiment, may support <NUM> V in a normal mode. In a cold crank case, the supply voltage of the first power supply may drop to lower bound above zero, usually <NUM> V, for a certain time, e.g. between <NUM>-<NUM>. The <NUM> V may mostly be a lower bound, i.e. the board net voltage does not drop below the <NUM> V. These <NUM> V may still be sufficient to provide power to the switch control unit <NUM> to operate the power switch <NUM>. A power switch control <NUM>, a relay control, may be operable with voltages below <NUM> V, for example <NUM> volts, such that, as a beneficial effect of the present invention, the first power supply <NUM> remains supplier for the switch control unit <NUM>. Therefore, in cold crank mode, an unnecessary load of the second power supply <NUM> may be avoided.

A further advantage of the present invention may be that the electronic unit <NUM> is persistently supported with voltages above the threshold voltage by the second power supply <NUM>. Hereby, the first and second power supplies <NUM>, <NUM> may be independent and/or separated from each other, as can be seen in the <FIG>, and only the first power supply <NUM> may be affected by the cold crank. Thus, the second power supply <NUM> may be configured to support the required power for the electronic unit <NUM> also during cold crank. The threshold voltage may preferably be set to be between <NUM> and <NUM> V, preferably between <NUM> and <NUM> V, even more preferably between <NUM> and <NUM> V. Electronic units <NUM> within the battery systems as the microprocessor <NUM> require <NUM> V as voltage input. Therefore, this threshold guarantees that voltage requirements are met throughout a crank cold time regime.

Also in the reverse case, when the voltage of the first power supply <NUM> rises back above the threshold voltage again, the switching unit <NUM> may be configured to electrically connect the first power supply <NUM> to the electronic unit <NUM> and electrically disconnect the second power supply <NUM> from the electronic unit <NUM>. Then, the original situation is reestablished. The time, in which the second power supply <NUM> is required, is thereby minimized, since by passing the threshold voltage, the first power supply is again available to provide sufficient power to the electronic unit <NUM> and the second power supply <NUM> is then not needed for this purpose anymore.

The switching unit <NUM>, as can be seen in this example embodiment, may be interconnected between the first power supply <NUM> and the electronic unit <NUM>, and interconnected between the second power supply <NUM> and the electronic unit <NUM>. Explicitly, a first input of the switching unit <NUM> may be electrically connected to the first power supply <NUM> and a second input is electrically connected to the second power supply <NUM>. Thereby, both voltages of the respective power supplies <NUM>, <NUM> are supplied to the switching unit <NUM>. The switching unit <NUM> then may comprise an output, wherein the output may be electrically connected to the electronic unit <NUM>. The described switching unit <NUM> is thereby an individual entity which receives in normal mode as well as in cold crank mode both power supply voltages of the respective power supplies <NUM>, <NUM> and supplies one of them to the electronic unit <NUM>. In alternative embodiments, the switching unit may be integral to the electronic unit <NUM>.

Referring to the second power supply <NUM>, the battery cell stack <NUM> may comprise a first node <NUM> and a second node <NUM>. Here, as example the nodes <NUM>, <NUM> are positioned at the opposite ends of the battery cell stack <NUM> such that potential difference refers to the system voltage VDD provided by the battery cell stack <NUM>, e.g. <NUM> V in the present case as example. The first node <NUM> may be grounded such that the second node <NUM> may refer to the high voltage node.

The second node <NUM>, in this particular embodiment, may be electrically connected to the second input of the switching unit <NUM>. Thereby, the high potential of the battery cell stack <NUM> may be supplied to the switching unit <NUM> and, in a state of cold crank, may be utilized to supply the electronic unit <NUM>, in particular the microprocessor <NUM>.

In this particular example, a voltage regulator <NUM> may be electrically interconnected between the second node <NUM> of the battery cell stack <NUM> and the switching unit <NUM>. In particular, the input of the voltage regulator <NUM> may be electrically connected to the second node <NUM> of the battery cell stack <NUM>, an output of the voltage regulator <NUM> may be electrically connected to the second input of the switching unit <NUM>. The voltage regulator <NUM> may be configured to reduce the input voltage, e.g. the <NUM> V, to an output voltage lower than the input voltage. This voltage may preferably be 5V as it is the operation voltage of a microprocessor <NUM> and many other electronic units <NUM>. In other embodiments, the voltage regulator <NUM> may be configured to output a voltage of at least 5V or of between <NUM> and <NUM> V, preferably between <NUM> and <NUM> V, even more preferably between <NUM> and <NUM> V. This output voltage can also be used to define or set the threshold voltage, see for example <FIG> or <FIG>.

The voltage regulator <NUM> may here be a low-dropout regulator, which typically only requires Zener-diode, resistors and a MOSFET and is thus by far less costly than a boost converter as used in the prior art. This additional external voltage regulator <NUM> is beneficial, as it creates the operational voltage from the too high output voltage of the battery cell stack <NUM> for the power consuming electronic units <NUM> in the cold crank mode, i.e., when the first power supply <NUM> cannot supply enough voltage in a transient cold crank time window of e.g. <NUM>-<NUM>. Then, the regulated voltage may be supplied to the electronic unit <NUM>, as can be seen in <FIG>.

Further, the power supply system may comprise a power supply regulator <NUM> interconnected between the switching unit <NUM> and the electronic unit <NUM>. The power supply regulator <NUM> is configured to regulate the received voltage to a particular operational voltage required by the electronic unit <NUM>, e.g. for a particular time interval or for particular tasks.

Only for completeness of the description of <FIG>, the power supply system <NUM> may further comprise an analog-front-end chip <NUM>, AFE to sense and receive analog data of various relevant parameters of the battery cell stack <NUM>. , as can be seen, a shunt <NUM> may be positioned in series with the first node <NUM>. Two nodes, <NUM>, <NUM> are connected on each side of the shunt <NUM> which are electrically connected to the AFE <NUM>. Thereby, charging/discharging current through the shunt <NUM> may be determined by the AFE <NUM> by measuring the (small) voltage drop across the shunt <NUM> for given predetermined (small) resistance. Other parameters to be measured may be the temperature or individual cell voltages (not shown here explicitly).

The AFE <NUM> may then send a state signal to the microprocessor <NUM> via a control line <NUM> indicative of the measured quantity. The microprocessor <NUM> may then send a control signal via control line <NUM> in response to the received state signal to the switch control unit <NUM>. For example, when the AFE <NUM> measures an analogue value indicative of a fault state of the battery cell stack <NUM>, a state signal indicative of the fault state may be sent to the microprocessor <NUM> via control line <NUM>. The microprocessor <NUM> may then in response send a control signal to control the relay control via control line <NUM> to switch the power switch when a fault state is detected.

<FIG> shows a power supply system <NUM> according to a second embodiment of the invention. In the following, only the differences with respect to <FIG> are described. For the same features it is hereby referred to the description of <FIG>.

In this preferred embodiment, a preferred switching unit <NUM> is described, which automatically selects the power supply <NUM>, <NUM> with the higher supply voltage. Therefore, the switching unit <NUM> may comprise a first diode <NUM>, a second diode <NUM> and an output node <NUM>.

The first power supply <NUM>, as can be seen in the <FIG>, may be electrically connected to the anode of the first diode <NUM>. The second power supply <NUM> may be electrically connected to the anode of the second diode <NUM>. The output node <NUM> may be electrically connected to the cathode of the first and second diode <NUM>, <NUM>, and wherein the output node <NUM> may be further electrically connected to the electronic unit <NUM>. The advantage of this particular embodiment is that the selecting works fully automatic. The connected diodes <NUM>, <NUM> select or set the power supply <NUM>, <NUM> with the higher voltage conductive and disconnect or set the power supply <NUM>, <NUM> with the lower voltage non-conductive.

In particular, the voltage applied to the anode of the second diode <NUM> coincides in this embodiment with the threshold voltage. Usually, due to the voltage regulator <NUM> in <FIG> or the internal voltage regulator <NUM> in <FIG>, this voltage may be set to 5V or slightly more, e.g. 5V plus the voltage drop across the second diode, but the invention is not restricted thereto.

Also here, the threshold voltage is between <NUM> and <NUM> V, preferably between <NUM> and <NUM> V, more preferably between <NUM> and <NUM> V.

A voltage below <NUM> V at the anode of the first diode <NUM> may set the first diode <NUM> non-conductive since it is then reverse biased, if <NUM> V are applied to the anode of the second diode <NUM>. Thus, the switching unit <NUM> effectively disconnects the first power supply <NUM>, while the second diode <NUM> is set conductive, since it is then forward biased. When the first power supply <NUM> recovers to a voltage above the threshold voltage after the cold crank time window, i.e. the voltage applied to the anode of the second diode <NUM>, the first diode <NUM> becomes forward biased and the second diode <NUM> reverse biased. Thus, the switching element <NUM> automatically disconnects the second power supply <NUM> and electrically connects the first power supply to the electronic unit <NUM>. Therefore, the switching unit has the advantage of a fully automatic switching unit without additional control units required.

In a preferred embodiment, the second diode <NUM> and/or the first diode <NUM> is a low drop-out diode. Low drop-out diodes are also referred to as active diodes. These diodes have a reduced inner voltage drop and voltage losses are reduced or even eliminated. When a voltage of 5V is applied to the anode of the second diode <NUM>, for example, substantially 5V are also supplied to the electronic unit <NUM> in a cold crank.

<FIG> shows a power supply system <NUM> according to a third embodiment of the present invention. Also in the following only the differences with respect to <FIG> are described. For the same features it is hereby referred to the description of <FIG>. Even though, the following embodiment is described with the specific switching unit <NUM> as described in <FIG>, it is clear that the following embodiment can also be combined with the features of <FIG>, only.

In this embodiment, the power supply system <NUM> may comprise as well an analog front end chip <NUM>, AFE. The AFE <NUM> is hereby electrically connected to the first node <NUM> and the second node <NUM> of the battery cell stack <NUM> to measure and receive the voltage in between the nodes <NUM>, <NUM>. Again, in other embodiments, the AFE <NUM> may receive cell voltages of individual battery cells <NUM> or sub stacks of the battery cell stack. Therefore, first node <NUM> and second node <NUM> may have different positions within the battery cell stack <NUM>. Here, in this preferred embodiment, the first node <NUM> and the second node <NUM> positioned at the respective ends of the battery cell stack <NUM>. The AFE <NUM> thus receives the system voltage VDD, typically <NUM> V, but the invention is not restricted thereto.

In this particular preferred embodiment, the AFE <NUM> may comprise an internal voltage regulator <NUM>. The internal voltage regulator <NUM> may be configured to reduce the received voltage to an output voltage lower than the input voltage. Preferably, the output voltage of the internal voltage regulator <NUM>, and thus from the AFE <NUM>, may be at least <NUM> V or exactly <NUM> V or slightly above to compensate for a voltage loss at the second diode <NUM>. The voltage may again be between <NUM> and <NUM> V, preferably between <NUM> and <NUM> V, more preferably between <NUM> and <NUM> V.

The AFE <NUM> may be configured to supply the output voltage to an output electrically connected to the second input of the switching unit <NUM> or, in case of the embodiment described in <FIG>, to the anode of the second diode <NUM>.

Also here, the internal voltage regulator <NUM> may be a low-dropout regulator. These regulators are preferably transistor-Zener-diode regulators, e.g. comprising resistors, transistors and Zener-diode, but the invention is not restricted thereto and also other voltage regulator implementations may be used.

In a further embodiment, when the electronic unit <NUM> is a microprocessor <NUM>, the microprocessor <NUM> may be configured to switch into a low power consumption mode. The condition for that may be that the microprocessor <NUM> detects that the supplied power or supplied current to the microprocessor <NUM> has dropped below a threshold power or threshold current, respectively. Since the power supplies, in particular from the voltage regulator <NUM> of the AFE <NUM> since it may be weaker than an external voltage regulator as in <FIG>, may support smaller currents, e.g. typically between <NUM> to <NUM> mA a low power consumption mode may be beneficial. This mode may be implementable by an application or computer program runnable on the microprocessor <NUM>, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functionalities described herein. The computer program instructions may be stored in a memory which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM).

Claim 1:
A power supply system (<NUM>) for cold crank functionality for providing power to components of a battery system of a vehicle, comprising:
- a microprocessor (<NUM>);
- a first power supply (<NUM>);
- the first power supply (<NUM>) electrically connected to the microprocessor (<NUM>) to electrically supply the microprocessor (<NUM>) in a normal mode;
- a second power supply (<NUM>);
characterized in,
- a relay control unit (<NUM>) for controlling a relay (<NUM>) to switch an external load;
- a switching unit (<NUM>) configured to:
electrically disconnect the first power supply (<NUM>) from the microprocessor (<NUM>) in a cold crank mode, whereas a cold crank mode occurs when the voltage of the first power supply (<NUM>) drops below a threshold voltage;
electrically connect the second power supply (<NUM>) to the microprocessor (<NUM>) in the cold crank mode, the second power supply (<NUM>) configured to electrically supply the microprocessor (<NUM>) in the cold crank mode; and
- the first power supply (<NUM>) is electrically connected to the relay control unit (<NUM>) to supply the relay control unit (<NUM>) in the normal mode and in the cold crank mode, whereas the relay control unit (<NUM>) is operable with voltages below the threshold voltage.