On-board power system for a motor vehicle and method for operating an on-board power system

Abstract

The invention relates to an on-board power system (B) for a motor vehicle. The motor vehicle comprises at least one battery cell unit (10) which is designed as a so-called SmartCell. In order to operate the battery cell unit (10), the on-board power system (B) furthermore comprises a control device (20). In order to be able to supply electrical energy, the control device (20) comprises a supply interface (V) for delivering a supply voltage (UV). As a rule, the supply voltage (UV) is delivered here by means of an energy supply device (30) of the on-board power system (B), which can be coupled to the control device (20) via a first coupling line (A1). In order to achieve a redundant energy supply of the control device (20), a second coupling line (A2) is provided in addition to the first coupling line (A1), via which the battery cells (11) of the respective battery cell unit (10) can be coupled to the supply interface (V). As a result, the supply voltage (UV) can be delivered via the first coupling line (A1) or via the second coupling line (A2), depending on the operating state of the energy supply device (30).

Description

Technical Field

[0001] This invention relates to an onboard electrical network for motor vehicles, the onboard electrical network including at least one battery cell unit, a control device, and an energy supply device. The invention also relates to a method for operating such an onboard electrical network. Background Technology

[0002] The typical function of this type of onboard electrical network is to ensure the energy supply to the electronic and electrical components of a motor vehicle. To this end, the onboard electrical network includes at least one or more of the aforementioned battery cell units, and its operating status or mode can be monitored and controlled by a control device. An energy supply device is typically provided to supply power to the control device.

[0003] As disclosed, for example, in US 2011 / 0210605 A1, the battery cell unit can be designed as a starter battery. To decouple or disconnect the starter battery from the remaining portion of the vehicle's electrical network in the event of a traffic accident, a mechanical battery disconnect switch is provided. A control device in the form of a microcontroller system is provided to operate the disconnect switch. Here, an energy supply device supplies electrical energy to the microcontroller system. This energy supply device can either draw its energy from the starter battery or, in the event of starter battery failure, from an emergency power supply device. This ensures redundant energy supply to the control device.

[0004] According to DE 10 2017 208 030 A1, battery cell units can also be used to supply safety power supplies to the vehicle's electrical network, such as those used in the brakes or steering systems of a motor vehicle. To ensure a reliable energy supply to these safety power supplies, the battery cell unit includes first and second battery cell branches, which can be coupled to and thereby supply energy to the safety power supplies depending on operating conditions. Therefore, the battery cell branches are used here for redundant energy supply to the safety power supplies.

[0005] However, battery cell units known from the prior art described above are not suitable for use in drive batteries or high-voltage batteries for electric drive systems used to operate motor vehicles.

[0006] For example, EP 3 576 241 A1 provides a vehicle electrical network with battery cell units for an electric drive system used to operate a motor vehicle. Here, a control unit is assigned to the battery cell unit, by means of which the operating parameters of the battery cell unit, such as state of charge or energy demand, can be monitored and controlled. Here, the control unit has two different operating modes: an active mode and a dormant mode. To operate in active mode, the control unit is connected to the entire circuit of the battery cell unit via a buck converter. Conversely, to operate in dormant mode, the control unit is additionally connected only to a branch of the battery cell unit. This specifically means that, depending on the adjusted operating mode, different voltage levels are provided to the control unit by means of the battery cell unit. However, redundant energy supply to the control unit is not provided here. Summary of the Invention

[0007] The object of the present invention is to provide a fail-safe control device for operating at least one battery cell unit of an on-board electrical network for a motor vehicle, the fail-safe meaning being particularly relevant to components of the motor vehicle's drive battery.

[0008] This objective is achieved through the subject matter of the independent claims. Advantageous improvements of the invention are disclosed through the dependent claims, the following description, and the accompanying drawings.

[0009] Therefore, as mentioned at the beginning, an on-board electrical network for motor vehicles, especially electric or hybrid vehicles, is provided. This on-board electrical network includes at least one, or one or more, battery cell units. These battery cell units typically include one or more battery cells or DC cells that can be interconnected in a known manner. Preferably, the respective battery cell units are assigned to the vehicle's drive battery or high-voltage battery. Thus, multiple battery cell units can be connected or combined into a drive battery, for example, in a known manner. To operate the respective battery cell units, the on-board electrical network further includes a control device. Operation specifically refers to controlling and monitoring the operating state of the respective battery cell units. Preferably, the control device is assigned to one or more battery cell units, for example, connected in parallel. The control device can be implemented, in particular, as a control circuit with one or more controllers. To supply electrical energy to the control device used to operate the battery cell units, the on-board electrical network further includes an energy supply device. The design of the energy supply device will be described in detail again below.

[0010] However, in modern electric or hybrid vehicles, the aforementioned battery cell units can be replaced, for example, by switchable battery cell units or Smartcell battery cells. Accordingly, the corresponding battery cell unit includes an activation circuit having a DC cell and a first semiconductor switch electrically connected in series with the DC cell. Furthermore, the battery cell unit also includes a bridging circuit having a second semiconductor switch electrically connected in parallel with the activation circuit. Thus, the control device is accordingly configured to operate the first and second semiconductor switches in a predetermined switching operation. That is, the control device can provide control signals for turning the semiconductor switches on or off. Here, switching operation means that the semiconductor switch can be switched to an on state and an off state. In the on state, the corresponding semiconductor switch has very good conductivity, thereby enabling a high current to flow through it. In the off state, the corresponding semiconductor switch is high-resistance, that is, it provides high resistance. Therefore, a negligible small current cannot be achieved, or can only be achieved, flowing through the corresponding semiconductor switch. Semiconductor switches, in particular, refer to controllable electronic switches, such as transistors, thyristors, especially transistor and thyristor combination circuits with parallel-connected freewheeling diodes, such as metal-oxide-semiconductor field-effect transistors (MOSFETs), preferably insulated-gate bipolar transistors (IGBTs) with integrated freewheeling diodes, etc.

[0011] In order to enable the switching of semiconductor switches by means of a control device, the control device includes a power supply interface for delivering electrical energy in the form of a supply voltage. Typically, the control device is coupled to an energy supply device via this power supply interface. Here, "coupled" specifically refers to electrical coupling, i.e., a conductive connection. Therefore, in this invention, the concepts of "connection" or "linkage" can also be used as synonyms for the concept of "coupled." That is, the supply voltage is typically provided to the power supply interface via an energy supply device.

[0012] However, in the event of a malfunction in the energy supply device, such as a failure, the control device may also malfunction. Because semiconductor switches are electronic switches, undefined switching states of the semiconductor switches may occur. Consequently, a malfunction in the energy supply device can lead to unexpected disconnection of the battery cells or unexpected short circuits in the battery cell unit.

[0013] To avoid this situation, this invention specifies that the power supply voltage is supplied to the control device in a redundant manner. Here, the aforementioned power supply interface, depending on the operating state or functionality of the energy supply device, can be coupled to the energy supply device via a first connection line and to at least one battery cell in the corresponding battery cell unit via a second connection line. Thus, depending on the operating state of the energy supply device, the power supply voltage is delivered to the power supply interface either via the first connection line (through which the control device can be coupled to the energy supply device) or via the second connection line (through which the control device can be coupled to the battery cell).

[0014] Preferably, during normal operation of the energy supply device, the supply voltage can be delivered to the power supply interface via the first connection line. Conversely, in the event of a malfunction in the energy supply device, the supply voltage can be delivered to the power supply interface via the second connection line. For example, a malfunction can be identified as an interruption or drop in voltage in the first connection line. Therefore, to deliver the supply voltage, either the battery cell voltage (provided by the battery cell) or the energy supply device voltage (provided by the energy supply device) can be used.

[0015] This results in the advantage that power can continue to be supplied to the control unit even in the event of a malfunction in the energy supply device. Here, the supply voltage is directly provided by the corresponding battery cell units, and especially by the battery cells themselves. This ensures the safety of the control unit and, consequently, the vehicle's drive battery in the event of failure.

[0016] The present invention also includes embodiments that produce additional advantages.

[0017] In embodiments of the invention, electrical energy is supplied to the control device from different parts of the vehicle-mounted electrical network. The vehicle-mounted electrical network includes a high-voltage grid as a first part of the power supply, and a low-voltage grid, separate from the high-voltage grid current, as a second part of the power supply. The battery cell unit and the control device are associated with the high-voltage grid, while the energy supply device is associated with the low-voltage grid. That is, in normal operation, the control device is supplied with power from the low-voltage grid. Conversely, in the event of a malfunction, energy is supplied directly from the high-voltage grid itself.

[0018] Here, in a known manner, the distinction between high-voltage and low-voltage power grids lies primarily in their voltage levels and their corresponding reference potentials or ground potentials. Thus, for example, a corresponding (high-voltage) voltage in the high-voltage grid, such as the supply voltage, can be extracted between the positive supply potential and the negative supply potential (as a reference potential). The supply voltage could, for example, be 20VDC (V: volt; DC: direct current). Conversely, for example, a corresponding (low-voltage) voltage in the low-voltage grid, such as the energy supply device voltage, can be extracted between the positive low-voltage potential and the negative low-voltage potential (as a reference potential) or ground potential (GND). The energy supply device voltage could, for example, be 12VDC.

[0019] To enable energy transfer between high-voltage and low-voltage power grids, the energy supply device is preferably coupled to the control device via a current-isolated conversion device, such as a DC / DC converter with current separation. For this purpose, the conversion device may, for example, be connected at one end to the energy supply device and at the other end to a first connection line of the control device. In this case, it is particularly preferred that the conversion device may also be configured to provide a so-called boost conversion function. Thus, the lower voltage of the energy supply device can be converted to a higher supply voltage using the conversion device.

[0020] In another embodiment of the invention, the control device further includes an additional conversion unit for the aforementioned battery cell voltage. That is, the conversion unit is configured to convert the battery cell voltage provided by the battery cell into a supply voltage. For this purpose, the conversion unit may, for example, be connected at one end to the battery cell of the battery cell unit and at the other end to a second connection line of the control device. Preferably, the conversion unit is configured as a DC / DC converter (without current separation) with a boost conversion function. That is, the battery cell used to drive the battery typically only provides a voltage between 2.5VDC and 4.2VDC. Thus, the conversion unit can boost the battery cell voltage to, for example, a supply voltage of 20VDC.

[0021] Now, in the following embodiments, different possibilities are realized for determining the corresponding operating states of the energy supply device. To this end, in embodiments of the invention, the control device additionally includes a communication interface for coupling with a communication device associated with the energy supply device. To determine the operating state, the control device constructs a communication signal provided by the communication device through the communication interface for evaluating the operating state. That is, the communication device can transmit the operating state to the control device in an encoded manner within the communication signal.

[0022] Here, the communication device may be, for example, part of the battery management system of the vehicle's electrical network. Preferably, the communication device is configured as a transceiver or converter (transmitter / receiver). This enables bidirectional signal transmission or communication between the control device and the communication device. For example, this communication can be achieved via bus communication, i.e., through a connection to the vehicle's CAN bus. Advantageously, the communication device is also arranged in the aforementioned low-voltage electrical network. To enable signal transmission between the communication device and the control device, the communication device is preferably connected to the communication interface of the control device via a current-insulated digital isolator.

[0023] In another embodiment of the invention, for determining the operating state of the energy supply device, the control device itself includes a sensor unit. The sensor unit is configured to acquire the voltage supplied by the energy supply device via a first connection line. The control device is configured to evaluate the acquired voltage according to predetermined evaluation criteria to determine the operating state of the energy supply device. For example, the control device may check whether the acquired voltage is within a predetermined voltage range according to the predetermined evaluation criteria. Here, this voltage range can be determined by predetermined voltage limit values. If the acquired voltage exceeds or falls below one of the corresponding voltage limit values, then a functional failure of the energy supply device can be inferred by the control device. For acquiring or measuring the voltage supplied via the first connection line, the sensor unit may include, for example, a voltage sensor or a current sensor.

[0024] The following embodiments realize the possibility of delivering different supply voltages through the first or second connection line depending on the operating state of the energy supply device. To this end, in another embodiment of the invention, the control device includes a disconnecting switch unit for the two connection lines. The control device is configured to switch the disconnecting switch unit to couple the first connection line to the power supply interface or to couple the second connection line to the power supply interface, depending on the operating state of the energy supply device. Thus, the corresponding connection line can be activated or deactivated by means of the disconnecting switch unit. In other words, active switching or transformation can be performed between the connection lines. For this purpose, the disconnecting switch unit may include, for example, one or more electronically operable changeover switches. Preferably, such changeover switches may be configured as relays, contactors, or semiconductor switches.

[0025] As an addition or alternative to active switching via a disconnecting switch unit, automatic switching from the energy supply device to the battery cell and vice versa is also possible. To this end, in another embodiment of the invention, the first and second connection lines are connected in parallel to the power supply interface. Furthermore, the energy supply device is configured to provide a voltage (first interface voltage) via the first connection line in a first normal operating state, which is larger than the voltage (second interface voltage) provided via the battery cell through the second connection line by a predetermined difference. In the event of a functional failure, the energy supply device is conversely configured to provide a first interface voltage smaller than the second interface voltage. This difference can be selected by those skilled in the art based on the design of the control device. Preferably, the difference can be between 0.1VDC and 1VDC. In normal operating state, the first interface voltage can be, for example, approximately 20VDC. Thus, in normal operating state, the second interface voltage can be, for example, 19VDC. Now, if a functional failure occurs in the energy supply device, it leads to an interruption of the energy supply device voltage and, consequently, the first interface voltage, as described at the beginning. Therefore, preferably, in the event of a functional failure, the first interface voltage has a smaller absolute value than the second interface voltage. The first interface voltage can be, for example, approximately 0VDC.

[0026] Now, connecting the two connection lines in parallel to the power supply interface has the advantage that the higher of the two voltages is always automatically provided as the supply voltage and delivered to the power supply interface. Therefore, the energy supply is particularly resistant to fluctuations in the voltage of the first interface or the energy supply device.

[0027] In another embodiment of the invention, an advantageous design is implemented for switch operation. Here, the control device is configured to operate the semiconductor switches in a clock-driven manner according to a predetermined switch operation during normal operation of the energy supply device. Conversely, in the event of a malfunction in the energy supply device, the control device is configured to switch the semiconductor switches to a predetermined switching state and preferably maintain them in that state. That is, each of the semiconductor switches is either switched to an ON state or a OFF state. Thus, switch operation is also related to the operating state of the energy supply device. Therefore, in the event of a malfunction, the defined switching state of the semiconductor switches can be adjusted. Furthermore, the energy consumption of the control device used to operate the semiconductor switches can be minimized or reduced.

[0028] Here, the aforementioned clock operation specifically refers to the cyclic switching of semiconductor switches according to a predetermined switching pattern. That is, multiple switching processes are set up sequentially, from an on state to an off state, and vice versa. For this purpose, the control device can, for example, provide a corresponding pulse-width modulated control signal to switch the corresponding semiconductor switch. Here, for example, the battery management system can select or predetermine the switching pattern based on the energy demand of the vehicle's electric drive system.

[0029] To monitor the battery cell units in terms of their functionality, in another embodiment of the invention, the control device includes a monitoring unit for the battery cell units. The monitoring unit is configured to acquire monitoring signals including at least one physical parameter of the battery cell unit. The control device is then configured to evaluate the corresponding monitoring signals to determine the operating state of the battery cell units. Furthermore, the control device is configured to store the corresponding monitoring signals in the event of a functional failure of the energy supply device in the control device's data memory. That is, the control device additionally includes a data memory for temporarily storing the corresponding monitoring signals.

[0030] Therefore, even when a functional failure of the energy supply device occurs, such as when the corresponding operating mode or failure of the battery cell unit can be diagnosed and recorded. Thus, the diagnosis or monitoring of the battery cell unit is typically performed within the aforementioned battery management system of the vehicle. As described above, the battery management system is usually located within the low-voltage power grid. However, in the event of a failure of the energy supply device, a failure of the low-voltage vehicle power grid may also occur, making it impossible to monitor the battery cell unit through the battery management system.

[0031] As physical parameters, such as the voltage, current, or temperature of the battery cell unit, can be acquired or measured. Therefore, the monitoring unit may also include, for example, at least one voltage sensor and / or at least one current sensor and / or at least one temperature sensor.

[0032] The present invention also relates to a method for operating the vehicle-mounted electrical network described above. Here, a power supply voltage is supplied to the control device of the vehicle-mounted electrical network via a power supply interface to cause semiconductor switches to operate at predetermined switching modes. Subsequently, the power supply interface is coupled to the energy supply device via a first connection line and to a corresponding battery cell of at least one of the corresponding battery cell units via a second connection line, according to the aforementioned operating state of the energy supply device.

[0033] The present invention also includes improvements to the method according to the invention, which have the features already described in conjunction with the improvements to the vehicle-mounted electrical network according to the invention. For this reason, corresponding improvements to the method according to the invention will not be described here.

[0034] The present invention also includes combinations of features of the described embodiments. Attached Figure Description

[0035] Embodiments of the present invention will now be described. For this purpose, the only accompanying drawing is:

[0036] A schematic diagram of a circuit for an onboard electrical network for a motor vehicle is shown, which has a redundant energy supply for the control device of the battery cell unit for operating the onboard electrical network. Detailed Implementation

[0037] The embodiments described below are preferred embodiments of the present invention. In the embodiments, the components of the described embodiments represent individual, independent features of the present invention, which also independently improve the present invention. Therefore, the disclosure should also include combinations of features different from those shown in the embodiments. Furthermore, the described embodiments may be supplemented by other features among the features already described in the present invention.

[0038] In the accompanying drawings, the same reference numerals denote elements that have the same function.

[0039] The accompanying diagram illustrates a schematic representation of an embodiment of an on-board electrical network B, for example, that can be installed in a motor vehicle. Here, the on-board electrical network B comprises two separate power sources: a low-voltage grid or low-voltage on-board electrical network NV and a high-voltage grid or high-voltage on-board electrical network HV. Here, in a known manner, the difference between these two power sources lies in their respective reference potentials. The low-voltage on-board electrical network NV currently includes a low-voltage positive potential NV+ and a ground potential GND as reference potentials, the ground potential being provided, for example, by the vehicle body. The high-voltage on-board electrical network HV currently includes a supply positive potential UV+ and a supply negative potential UV- as reference potentials.

[0040] The high-voltage vehicle-mounted electrical network (HV) includes a battery cell unit 10 for providing electrical power to the drive unit of a motor vehicle, and a control device 20 for controlling and monitoring the battery cell unit 10. Thus, the battery cell unit 10 can be part of the drive battery of the motor vehicle. To form the drive battery, the battery cell unit 10 can, for example, be interconnected with one or more other battery cell units via a battery cell interface AB in a known manner. As shown in the figures, the battery cell unit 10 is configured as a so-called SmartCell. That is, the battery cell unit 10 includes an activation line AL having a battery cell 11 and a first semiconductor switch 12 connected to the positive terminal of the battery cell 11 via a first end. Furthermore, the battery cell unit also includes a bridging line. The bridging circuit includes a second semiconductor switch 13. Here, the second semiconductor switch 13 is connected to the negative terminal of the battery cell 11 via its first terminal. Furthermore, the two semiconductor switches 12 and 13 are directly connected to each other via their respective second terminals. Here, the semiconductor switches 12 and 13 are configured, for example, as metal-oxide-semiconductor field-effect transistors (MOSFETs) with parallel-connected freewheeling diodes.

[0041] Now, by designing the battery cell unit 10 as a SmartCell, it is possible to adjust the voltage supplied to the electric drive device through the battery cell interface AP. For this purpose, the first and second semiconductor switches 12 and 13 can operate in a predetermined switching mode. That is, for example, the semiconductor switches 12 and 13 can be alternately or cyclically switched between on / off and deactivated states, depending on the energy demand of the drive device. This avoids the simultaneous activation or deactivation of the semiconductor switches 12 and 13 during switching operation, which could potentially cause a short circuit in the battery cell 11.

[0042] The operation of semiconductor switches 12 and 13 is a function of control device 20. For this purpose, control device 20 includes controller 21, which may be configured as a microcontroller. A gate driver 24 is connected to controller 21. Semiconductor switches 12 and 13 can be switched according to corresponding control commands from controller 21 by means of gate driver 24. Preferably, gate driver 24 has logic gates or logic circuits to always lock one of semiconductor switches 12 and 13 accordingly and thus keep it in a deactivated switching state. This effectively prevents the simultaneous on / off of semiconductor switches 12 and 13. In MOSFETs, switching is typically achieved by adjusting the so-called gate voltage of the corresponding semiconductor switches 12 and 13, i.e., switching to a defined switching state. For example, setting a gate voltage of 15VDC can switch the corresponding semiconductor switches 12 and 13 to an on switching state and thus switch them to a state where they can conduct very well. Conversely, setting a gate voltage of -8VDC can switch the corresponding semiconductor switches 12 and 13 to an off or high-resistance switching state.

[0043] The gate voltage typically does not involve the positive and negative supply potentials UV+ and UV- of the high-voltage vehicle electrical grid HV. Therefore, to provide the gate voltage, the control device 20 includes a current-separated gate switching unit 25, which is connected to the positive and negative supply potentials UV+ and UV-. The gate switching unit 25 enables a current-separated drive power supply TN with a reference potential different from that of the positive and negative supply potentials UV+ and UV-. The drive power supply TN includes the positive and negative gate potentials G+ and G- as reference potentials, between which a corresponding gate voltage can be intercepted.

[0044] In order to achieve the control of the battery cell unit 10 described above, a power supply is provided for the control device 20 and, in particular, the controller 21. For this purpose, the control device 20 includes a power supply interface V, through which the control device 20 is connected to the positive supply potential UV+ and the negative supply potential UV-. The supply voltage UV can be supplied to the control device 20 through the power supply interface V.

[0045] Typically, the supply voltage UV is provided to the power interface V via a low-voltage vehicle electrical network NV. For this purpose, the low-voltage vehicle electrical network NV includes an energy supply device 30, which is configured, for example, as a DC / DC converter connected to a low-voltage positive potential NV+ and a ground potential GND. Thus, the voltage, defined in detail below, that can be intercepted between the low-voltage positive potential NV+ and the ground potential GND, can be converted into the energy supply device voltage UE by means of the DC / DC converter. During normal operation of the energy supply device 30, the energy supply device voltage UE can be, for example, 12VDC.

[0046] To supply the energy supply device voltage UE to the control device 20, as shown in the accompanying drawings, the energy supply device 30 is connected to the first connection line A1 of the control device 20 via a current-separated conversion device 31. The first connection line A1 is in turn directly connected to the power supply interface V. Thus, the energy supply device voltage UE generated by the energy supply device 30 can be converted into a first interface voltage UA1 that can be intercepted in the first connection line A1. Subsequently, the first interface voltage UA1 can be supplied to the power supply interface V as a power supply voltage. During normal operation of the energy supply device 30, the first interface voltage UA1 can, for example, be 20V. Accordingly, the conversion device 31 can be configured, for example, as a current-isolated boost converter to increase the energy supply device voltage UE to the first interface voltage UA1. To prevent the control device 20 from also transmitting electrical energy to the low-voltage vehicle power grid, a freewheeling diode is additionally connected to the first connection line.

[0047] To supply the power supply voltage UV to the controller 21, the controller 21 is connected to the power supply interface via a conversion unit 22. Here, the conversion unit 22 is configured as a DC-DC voltage step-down converter. Thus, the power supply voltage UV present at the power supply interface V can be reduced to a controller voltage US for supplying to the controller 21. During normal operation of the energy supply device 30, the controller voltage US can be, for example, 5VDC.

[0048] However, if a functional failure occurs in the low-voltage vehicle electrical network NV, and consequently, a functional failure occurs in the energy supply device 30, then the supply of energy to the control device 20 from the low-voltage vehicle electrical network NV can no longer be guaranteed. A functional failure could be, for example, a complete failure of the energy supply device 30. Alternatively, a functional failure could also be a temporary limitation or temporary fluctuation in the energy supply device voltage UE. Thus, compared to the absolute value of the energy supply device voltage UE in normal operation, the functional failure results in an interruption or decrease in the energy supply device voltage UE. Therefore, a decrease in the first interface voltage UA1 may also occur, thus preventing the control device 20 from receiving a complete supply voltage, such as 20VDC. Consequently, there is no longer sufficient electrical energy to supply the controller 21, gate driver 24, and gate converter 25, and undefined switching states of semiconductor switches 12 and 13 may occur. Thus, for example, undesirable bridging of battery cell 11 may occur, or battery cell unit 10 may be short-circuited with other battery cell units of the drive battery.

[0049] To avoid the cascading effects of events in the event of a failure of the energy supply device 30, redundant energy is supplied directly from the high-voltage vehicle-mounted power grid HV. Here, the energy supply source is provided by the battery cells 11 of the battery cell unit 10. For this purpose, the battery cells 11 (using their positive and negative terminals respectively) are connected to the second connection line A2 via another conversion unit 23. Thus, the second connection line A2 is directly connected to the power supply interface V in parallel with the first connection line A1. Therefore, the battery cell voltage UB generated by the battery cells 11 can be converted into a second interface voltage UA2 that can be intercepted in the second connection line A2. The typical value of the battery cell voltage UB is usually between 2.5VDC and 4.2VDC. Therefore, the conversion unit 23 can be configured, for example, as a DC-DC voltage boost converter. Thus, the battery cell voltage UB can be boosted to the second interface voltage UA2. Subsequently, the second interface voltage UA2 can be supplied to the power supply interface V as the supply voltage UV.

[0050] Here, during normal operation of the energy supply device 30, a voltage absolute value slightly smaller than the absolute value of the first interface voltage UA1 is selected or set for the second interface voltage UA2. For example, the second interface voltage UA2 can be 19.5VDC. Thus, depending on the operating state of the energy supply device 30 (normal operation or functional failure), the supply voltage UV can be automatically provided via the first or second connection lines A1, A2. This allows for particularly rapid switching or transformation of the energy source supplying the control device 20 within the vehicle electrical network B. It also allows for easy balancing of slight fluctuations or voltage interruptions in the low-voltage vehicle electrical network NV.

[0051] However, as mentioned at the beginning, the control device 20 not only controls the battery cell unit 10, but also additionally monitors the operating parameters of the battery cell unit 10. For this purpose, the control device 20 includes a voltage sensor 26, a current sensor 27, and a temperature sensor 28, each individually connected to the controller 21. Thus, the corresponding physical parameters of the battery cell unit 10 can be measured using these sensors and provided to the controller as monitoring signals for evaluation. For example, the battery cell voltage UB can be measured as a physical parameter using the voltage sensor 26. The current supplied by the battery cell unit 10 can be measured as a physical parameter using the current sensor 27. Finally, the temperature can be measured as a physical parameter using the temperature sensor 28. In the subsequent evaluation, the controller can, for example, check whether the corresponding physical parameters are within the expected value range. From this, a functional failure of the battery cell unit 10 can be inferred. Preferably, the operating mode of the battery cell unit 10 is determined by evaluating one or more monitoring signals using the controller 21.

[0052] To enable individual monitoring of each battery cell 10 and overall monitoring of the multiple battery cell units that together form the drive battery, it is preferable to transmit a defined operating mode, for example as an operating mode signal, to the vehicle's battery management system. The battery management system is typically located in the low-voltage vehicle electrical network NV. Here, the battery management system is shown, for example, via a communication device 40 in the low-voltage vehicle electrical network NV. For transmitting the operating mode signal, the control device 20 additionally includes a communication line K or communication interface directly connected to the controller 21. The communication device 40 is now connected to the communication line K via a digitizer 41 or a digital isolator with current separation. Preferably, the communication device 40, digitizer 41, and controller 21 can be configured for bidirectional signal transmission. Thus, for example, control commands can also be provided to the control device 20 by the battery management system.

[0053] To ensure that battery cell unit 10 can be monitored even in the event of a functional failure in the low-voltage power grid, controller 20 preferably includes a data memory (not shown in the accompanying drawings). Thus, in the event of a functional failure, the corresponding operating mode signal in the form of operating data can be temporarily stored in the data memory until, for example, communication with communication device 40 can be restored. Therefore, even if the communication connection with the low-voltage vehicle power grid NV fails, battery cell unit 10 can still be monitored.

[0054] As an alternative to the embodiment shown in the accompanying drawings, instead of automatically selecting the energy supply source, the device can actively switch to the corresponding energy supply source. For this purpose, the control device 20 may include, for example, a separate unit in the form of a changeover switch, which can electrically couple either the first electrical connection line to the power supply interface or the second connection line to the power supply interface, depending on the functionality of the energy supply device 30. To determine the functionality of the energy supply device 30, the controller 21 of the control device 30 may, for example, monitor the first interface voltage UA1. Alternatively, the operating status of the energy supply device 30 can also be transmitted to the controller 21 of the control device 20 via the communication device 40.

[0055] According to this alternative embodiment of the vehicle-mounted electrical network B, a corresponding method for operating the vehicle-mounted electrical network B may include the following steps (not shown). In the decision-making step, functionality, i.e., the operating status of the energy supply device 30, is first checked, as described above. If the controller 21 determines that the energy supply device 30 is operating normally, then the controller 21 may operate the disconnect switch unit to electrically connect the first connection line A1 to the power supply interface V. Thus, the supply voltage UV can be supplied to the control device 20 via the energy supply device 30. Conversely, if it is determined during the check that the energy supply device 30 has a functional failure, then the controller 21 may instead operate the disconnect switch unit to electrically disconnect the first connection line A1 from the power supply interface V and electrically connect the second connection line A2 to the power supply interface V. Thus, the supply voltage UV for operating the control device 20 can be provided via the battery cell 11.

[0056] Therefore, the examples generally demonstrate how redundant energy supply can be provided in SmartCells used in electric vehicles.

Claims

1. An on-board electrical system (B) for a motor vehicle, comprising at least one battery cell unit (10), a control device (20) and an energy supply device (30), characterized in that The corresponding battery cell unit (10) includes: an activation line (AL) having a battery cell (11) and a first semiconductor switch (12) electrically connected in series with the battery cell; and a bridge line (ÜL) electrically connected in parallel with the activation line (AL) having a second semiconductor switch (13). The control device (20) is configured to operate the first and second semiconductor switches (12, 13) with predetermined switch operation. The control device (20) has a power supply interface (V) for delivering a supply voltage (UV), wherein the power supply interface... (V) Depending on the operating status of the energy supply device (30), it can be coupled to the energy supply device (30) via a first connection line (A1) and to at least one of the battery cells (11) of the corresponding battery cell units (10) via a second connection line (A2), wherein the control device (20) has a communication interface (K) for coupling with a communication device (40) associated with the energy supply device (30), and the control device (20) is configured to evaluate the communication signals provided through the communication interface (K) to determine the operating status of the energy supply device (30).

2. The on-board electrical system (B) according to claim 1, wherein The vehicle-mounted electrical network (B) includes a high-voltage grid (HV) and a low-voltage grid (NV) that is current-separated from the high-voltage grid. The battery cell unit (10) and the control device (20) are associated with the high-voltage grid (HV), and the energy supply device (30) is associated with the low-voltage grid (NV).

3. The on-board electrical system (B) according to claim 1 or 2, wherein The control device (20) has a conversion unit (23) configured to convert the battery cell voltage (UB) provided by the battery cell (11) into a supply voltage (UV).

4. The on-board electrical network (B) according to claim 1 or 2, wherein, The control device (20) includes a sensor unit configured to acquire a voltage supplied by an energy supply device (30) via a first connection line (A1), and the control device (20) is configured to evaluate the acquired voltage according to a predetermined evaluation criterion to determine the operating state of the energy supply device (30).

5. The on-board electrical network (B) according to claim 1 or 2, wherein, The control device (20) includes a disconnecting switch unit for two connection lines (A1, A2), wherein the control device (20) is configured to switch the disconnecting switch unit according to the operating state of the energy supply device (30) to couple the first connection line (A1) to the power supply interface (V) or to couple the second connection line (A2) to the power supply interface (V).

6. The on-board electrical network (B) according to claim 1 or 2, wherein, The first and second connection lines (A1, A2) are connected in parallel to the power supply interface (V). The energy supply device (30) is configured to provide a voltage (UA1) through the first connection line (A1) in normal operation, which is greater than the voltage (UA2) provided by the battery cell (11) through the second connection line (A2). The energy supply device (30) is also configured to provide a voltage (UA1) through the first connection line (A2) in the event of a malfunction, which is less than the voltage (UA2) provided by the battery cell (11) through the second connection line (A2).

7. The on-board electrical network (B) according to claim 1 or 2, wherein, The control device (20) is configured to operate the semiconductor switches (12, 13) in a clock-operated manner according to a predetermined switching operation during normal operation of the energy supply device (30), and the control device (20) is configured to switch the semiconductor switches (12, 13) to a predetermined switching state in the event of a functional failure of the energy supply device (30).

8. The on-board electrical network (B) according to claim 1 or 2, wherein, The control device (20) includes a monitoring unit (26, 27, 28) for the battery cell unit (10), the monitoring unit being configured to acquire a monitoring signal including at least one physical parameter of the battery cell unit (10), and the control device (20) being configured to evaluate the corresponding monitoring signal to determine the operating state of the battery cell unit (10), and to store the corresponding monitoring signal in the data storage of the control device (20) in the event of a functional failure of the energy supply device (30).

9. A method for operating an onboard electrical network (B), wherein, The on-board electrical network (B) has at least one battery cell unit (10), a control device (20), and an energy supply device (30). The battery cell unit (10) comprises: an activation line (AL) having a battery cell (11) and a first semiconductor switch (12) electrically connected in series with the battery cell; and a bridge line (ÜL) electrically connected in parallel with the activation line (AL) having a second semiconductor switch (13). The control device (20) is configured to operate the first and second semiconductor switches (12, 13) with predetermined switch operation. The control device (20) has a power supply interface (V) for delivering a supply voltage (UV). The control device (20) is configured to evaluate the communication signals provided through the communication interface (K) to determine the operating status of the energy supply device (30). The control device (20) delivers the supply voltage (UV) to the power supply interface (V) via the first connection line (AL) through the energy supply device (30) or via the second connection line (A2) through the battery cell (11) of at least one of the corresponding battery cell units (10). The control device (20) has a communication interface (K) for coupling with a communication device (40) associated with the energy supply device (30). The control device (20) is configured to evaluate the communication signals provided through the communication interface (K) to determine the operating status of the energy supply device (30).

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