Control device and method for actively reducing voltage in a high-voltage system

Abstract

A control device is provided for operating a battery-electric vehicle after an accident. The control device is designed to disconnect the vehicle's high-voltage storage system from the high-voltage system (comprising high-voltage components) on all poles after the accident. Following disconnection, the device uses a measuring device to detect the remaining voltage on a Y-junction of the high-voltage system, depending on the state of the measuring device, which has an active and an inactive state. The control device is designed to switch the measuring device to the active state and couple it to the Y-junction in order to actively dissipate the detected residual voltage in the Y-junction.

Description

The present disclosure relates to a control device for operating a battery-electric motor vehicle after an accident situation and / or to a method for controlling an operation of a battery-electric motor vehicle after an accident situation. Additionally, or alternatively, there is provided a computer program comprising instructions which, when the program is executed by a computer, cause the computer to at least partially execute the method. Additionally, or alternatively, there is provided a computer readable medium comprising instructions which, when the instructions are executed by a computer, cause the computer to at least partially execute the method.Driver assistance systems can have functions for putting BEV (battery electric vehicle) and PHEV (plug-in hybrid vehicles) into a risk-free and / or non-critical system state in hazardous situations and / or accident situations. In known BEV and PHEV motor vehicles, after an accident situation and a subsequent triggering of the accident safety measures, electrical energy may still be present in the high-voltage system (HV system) of the motor vehicle. There may still be a voltage between the poles of the HV system and the body of the motor vehicle. Knowing whether a voltage is applied to the body or whether the motor vehicle is stress free after an accident is important to rescue workers and other persons who must assist with a BEV after an accident or rescue the motor vehicle.In technical implementation, the known systems do not have an active discharge of the motor vehicle under voltage. Instead, it is provided to design the HV system in such a way that it projects beyond an accident without damage and therefore no voltage can be applied to the body which would pose a risk to third parties. However, the damage-free design of the HV system in technical implementation is complicatedFurthermore, a discharge of Y capacitors can be provided. US2020 / 0127469A1 proposes a battery module for use in an electric vehicle. The battery module includes a power source and an insulation monitoring circuit electrically connected to the power source. The electric vehicle includes a Y capacitor module. The insulation monitoring circuit may discharge the Y capacitor module when the battery module is electrically connected to the electric vehicle. The insulation monitoring circuit in the battery module is used as a discharge device to discharge the Y capacitor when the energy content of the Y capacitor is greater than the predetermined threshold.Against the background of this prior art, the object of the present disclosure is to specify an apparatus and / or a method which are each suitable for improving the prior art.The object is achieved by the features of the independent claims. The subordinate claims and the dependent claims each have optional developments of the disclosure.The object is then achieved by a control device for operating a battery-electric motor vehicle after an accident situation. The control device is designed to disconnect a high-voltage accumulator of the motor vehicle from a high-voltage system comprising high-voltage components in all poles after the accident situation. Furthermore, the control device is configured to detect a remaining voltage on a Y path of the high-voltage system as a function of the state of the measuring device after the high-voltage accumulator has been disconnected by means of a measuring device, wherein the measuring device has an active state and an inactive state. In addition, the control device is designed in such a way that it switches the measuring device into the active state and couples it to the Y path in order to actively reduce the detected stress remaining in the Y path.The control device or control unit can be part of or represent the driver assistance system. The control device may be, for example, an electronic control unit (engl. ECU=electronic control unit). The electronic control unit can be an intelligent processor-controlled unit which can communicate with other modules, for example via a central gateway (CGW), and which can optionally form the vehicle electrical system via fieldbuses, such as the CAN bus, LIN bus, MOST bus, FlexRay and / or via the automotive Ethernet, for example together with telematics control units and / or a surroundings sensor system.It is conceivable that the control device controls functions relevant to the driving behavior of the motor vehicle, such as the steering, the engine control, the force transmission, the energy management and / or the brake system. In addition, driving assistance systems, such as a parking assistant, may include an adjusted cruise control (ACC. Adaptive cruise control), a lane keeping assistant, a lane changing assistant, a traffic sign recognition, a light signal recognition, a starting assistant, a night vision assistant and / or an intersection assistant can be controlled by the control device. Furthermore, the control device can provide control signals for controlling further components of the motor vehicle and / or for controlling switching components.For purposes of disclosure, an accident situation with respect to a battery electric vehicle (BEV) may refer to a situation where the BEV is involved in a collision, collision, or other incident that may have caused damage to the motor vehicle. In an accident situation, the BEV may be damaged by an external force such as the impact of another vehicle, a collision with an obstacle, or other circumstances. This can lead to damage to the vehicle body, the drive components, the HV system, the high-voltage accumulator (HV accumulator) and / or other systems of the motor vehicle. In an accident situation, specific risks may exist in connection with the high-voltage system. In the event of a collision, there may be the possibility of damage to the high-voltage components, such as the high-voltage accumulator, the cables or the control units. These damage can lead to leaks, short circuits or other electrical hazards. Furthermore, in the event of severe damage to the motor vehicle, there may be the potential risk of the high-voltage accumulator undergoing thermal runaway. This relates to uncontrolled overheating or ignition of the high-voltage accumulator on account of damage or malfunctions. In an accident situation, it may be decisive that specific methods for protecting the high-voltage system are observed and carried out in order to minimize the risk of injuries or further damage.In the sense of the present disclosure, a high-voltage accumulator in a battery-electric vehicle (BEV) can consist of or comprise a plurality of battery modules or cell packs, which can be connected in series in order to generate a higher overall voltage. Each battery module may include a plurality of battery cells. The number of poles in a high-voltage accumulator may depend on the type of battery cells and the configuration of the system. Conventional lithium-ion batteries have two poles: a positive (+) pole and a negative (-) pole. The total number of poles may depend on the number of battery modules connected in series. The voltage between the poles of a high-voltage accumulator can be designed to be very high and can comprise several hundred volts to thousands of volts, depending on the battery system and configuration.In the sense of the present disclosure, the all-pole disconnection of a high-voltage accumulator can relate to the process in which the connection of all poles of the high-voltage accumulator is simultaneously disconnected in order to ensure that there is no longer any electrical voltage or current flow between the high-voltage components. This is an important safety mechanism that allows to operate on high voltage components in electric vehicles or to tow the vehicle without having the risk of electric current shock. All-pole disconnection can be effected via a switch or a safety device. These switches or fuses may be designed such that they are capable of interrupting the circuit between all poles of the high-voltage accumulator.For the purposes of the present disclosure, the "Y path" refers to the electrical path or the connection which leads from the high-voltage accumulator to the drive motors. The high-voltage system in a BEV can comprise the high-voltage accumulator, the electrical cables, plug connectors, contactors, inverters and / or the drive motors. The Y path is part of the system in which the high-voltage accumulator provides the electrical energy to the drive motors. The "Y-path" optionally denotes the phase-by-phase arrangement of the components. In this design, the high-voltage accumulator can be considered as the starting point from which electrical cables or busbars lead to the drive motors in a Y-shaped distribution. The Y path may allow efficient distribution of the electrical energy from the high-voltage accumulator to the drive motors as a main path for the electrical current flow and may include various contactors, inverters or other control components.The above-described device offers a number of advantages. Inter alia, the control device according to the disclosure can ensure that the HV system and the HV components are free of voltage after the high-voltage accumulator has been disconnected. Furthermore, a reduction of remaining voltage in the HV system and / or the HV components can take place in an accelerated manner, so that after an accident situation the motor vehicle can be safely rescued by third parties.Possible refinements of the above-described device are explained in detail below.It can be provided that the measuring device comprises an insulation monitoring device. Furthermore, it can be provided that the measuring device comprises an insulation monitor. The isolation monitor may be a safety mechanism in a BEV or PHEV that monitors the isolation integrity of the high voltage system. It can detect possible insulation faults or reductions in the insulation resistances and trigger a shutdown of the high-voltage system in certain situations in order to ensure and / or restore safety. The state or position of the isolation monitor at the shutdown instant refers to the time at which the isolation monitor detects the isolation fault or the reduction in isolation integrity and initiates the shutdown of the system. Depending on the specific configuration of the high-voltage system and the insulation monitor, the voltage present in the system at the time of shutdown may vary. If the isolation monitor detects an isolation fault early and initiates the shutdown of the RF system, the voltage in the RF system may be relatively low. On the other hand, if the isolation monitor detects an isolation fault only late or not at all, the voltage in the system may be higher at the time of shutdown. The magnitude of the voltage at the shutdown torque may have various effects, including the possible risk of an electric current surge or the impairment of the safety of other high-voltage components.An insulation monitoring device may be a device or system used in electrical equipment or equipment to monitor the integrity of the electrical insulation. It may serve to detect possible insulation faults or leakage currents that may occur and could cause potential hazards. The insulation monitor may operate based on the insulation resistance that measures the degree of insulation between the conductive parts and the ground potential. It can continuously monitor the insulation resistance and compares it with a predetermined threshold value. If the insulation resistance falls below this threshold value, an optional alarm is triggered or a protective measure is initiated. The insulation monitoring device can be used in high-voltage systems, such as are used in battery-electric vehicles (BEVs). It serves to detect possible insulation faults in the high-voltage components, such as batteries, inverters, cables or plug connectors. Isolation monitors optionally ensure that the electrical systems are properly isolated and safety of third party devices and devices is ensured. If an insulation fault is detected, the insulation monitoring device can optionally trigger various protective measures, comprising a disconnection of the circuit, an alarm and / or an error message.It can be provided that the reduction of the voltage comprises a discharge of Y capacitors of the high-voltage components. In addition to the high-voltage accumulator and / or further energy accumulator (fuel cell) for providing the supply energy, further energy accumulators are also provided in the high-voltage system, which optionally cannot be switched off by switching elements but rather have to be discharged. These can optionally not be disconnected from the on-board power supply system via switching elements, since this would be technically too costly. These smaller energy stores can be capacitors which can be provided directly in the HV components for buffering energy (so-called X capacitances) or for suppression of interference (Y capacitors). The Y capacitors here couple the respective HV components capacitively to the electrical ground of the vehicle. In addition, high-resistance insulation resistors are installed between the high-voltage on-board electrical system and the ground. Accelerated voltage dissipation by discharging the Y capacitors may increase safety for third parties to the motor vehicle.It can be provided that the coupling of the measuring device comprises a coupling to the high-voltage negative side of the Y path. The voltage in the Y capacitors of the high-voltage components can thereby optionally be reduced in an accelerated manner.It can be provided that the disconnection of the high-voltage system from the high-voltage accumulator takes place via controllable switching elements and monitoring of the switching elements is provided via switching element adhesion detection. In the sense of the present disclosure, the actuatable switching elements can be designed as contactors. Alternatively or additionally, further / other components can be provided, via which a corresponding voltage and / or currents can be switched for operating the high-voltage system. Switching element stick detection refers to a function or system in a battery electric vehicle (BEV) that serves to monitor the state or integrity of the switching elements and maintain a verifier switching state as well as detect potential issues early.It can be provided that the switching elements have at least one resistance element bridging the switching element. A switching element bridging resistive element is used in switching elements to limit current flow through the coil of the contactor when the switching element is not actuated. It may be connected in parallel to the switching element coil. The main object of the switching element bridging resistance element may be to prevent occurrence of switching sparks and to increase the life of the switching element. Furthermore, adhesive bonding (welding) of the switching units (opener, closer, changer) in the switching element is to be detected and / or avoided.The above description can be summarized in other words and on a possible more specific configuration of the disclosure as described below, wherein the following description is to be interpreted as not restrictive for the disclosure.In BEV vehicles, after a crash shutdown in the HV system, a voltage may still remain between the HV poles and the vehicle body. This to solve and speed its degradation is achieved by the present disclosure. In known systems, no active discharge of the HV system takes place, since corresponding manufacturers have designed the HV system to be free of damage in the event of a crash. This can potentially lead to problems in homologation. Because voltage still remains on the y-path after crash shutdown of the HV system (all-pole disconnection of the HV accumulator from the HV system and rapid discharge on the system side), this discharge must be performed. The level of the voltage depends on the position of the insulation monitor at the switch-off moment. Since it is provided to release the contactor stick detection by means of contactor-bridging resistors, the Y path can be actively discharged from the vehicle via the latter by an active position of the insulation monitor on the HV minus side. An implementation can be effected by corresponding control by means of a computer program.Furthermore, a motor vehicle having the above-described control unit or control device is provided.The motor vehicle can be a passenger car, in particular an automobile, or a commercial vehicle, such as a truck.The motor vehicle may be automated. The motor vehicle can be configured to at least partially and / or at least temporarily adopt longitudinal guidance and / or transverse guidance by means of the control device during automated driving of the motor vehicle.The automated driving can be carried out in such a way that the transportation vehicle is (largely) autonomously moved. The automated driving can be controlled at least partially and / or temporarily by the control device.It is conceivable for the motor vehicle to actively intervene in the transverse guidance of the motor vehicle by a driving assistance system, e.g. by adapting an actual steering wheel position, and optionally passively, e.g. by displaying a turn notice.The motor vehicle may be a motor vehicle of level 0 of autonomy, i.e., the driver performs the dynamic driving task even when supporting systems (e.g., ABS or ESP) are present.The motor vehicle may be a motor vehicle of level 1 of autonomy, i.e. may have certain driver assistance systems which assist the driver in vehicle operation, such as the cruise control (ACC) speed.The motor vehicle may be a motor vehicle of level 2 of autonomy, i.e. may be partially automated in such a way that functions such as automatic parking, lane keeping or lateral guidance, general longitudinal guidance, acceleration and / or deceleration of driver assistance systems are adopted.The motor vehicle can be a motor vehicle of the level 3 of autonomy, i.e. conditionally automated in such a way that the driver does not have to continuously monitor the system of the vehicle. The motor vehicle independently performs functions such as triggering the turn signal, lane change and / or lane keeping. The driver can devote to other attacks, but if necessary is requested to take over guidance within a pre-warning period of time by the system.The motor vehicle can be a motor vehicle of the level of autonomy 4, i.e. be highly automated to such an extent that the guidance of the vehicle is permanently taken over by the system of the vehicle. If the driving tasks are no longer managed by the system, the driver can be requested to take over the guidance.The motor vehicle may be a motor vehicle of the level of autonomy 5, i.e. be fully automated in such a way that the driver is not required to fulfil the driving task. Besides the destination setting and starting of the system, no human intervention is required. The motor vehicle can manage without steering wheel and pedals.The description above with reference to the control device applies analogously also to the motor vehicle and vice versa.Further provided is a method for controlling operation of a battery electric motor vehicle after a crash situation. The motor vehicle has a high-voltage accumulator and a high-voltage system having high-voltage components. The method comprises: all-pole disconnection of the high-voltage accumulator from the high-voltage system after the accident situation; detection of a remaining voltage on a Y path of the high-voltage system via a state-dependent measuring device after disconnection of the high-voltage accumulator, the measuring device has an active state and an inactive state; and switching the measuring device into the active state and coupling it to the Y path in order to actively reduce the detected voltage remaining in the Y path.The control method can be a computer-implemented method, i.e. one, several or all steps of the method can be executed at least partially by a computer or a device for data processing, optionally the control device.The description above with reference to the control device and to the motor vehicle applies analogously also to the method and vice versa.Furthermore, a computer program comprising instructions which, when the program is executed by a computer, cause the computer to at least partially carry out or carry out the method described above is provided. A program code of the computer program can be present in any code, in particular in a code suitable for controllers of motor vehicles.The description above with reference to the control device, the motor vehicle and the method also applies analogously to the computer program and vice versa.Furthermore, a computer-readable medium, in particular a computer-readable storage medium, is provided. The computer-readable medium includes instructions that, when the instructions are executed by a computer, cause the computer to at least partially perform the methods described above.That is, a computer readable medium including a computer program as defined above may be provided. The computer readable medium may be any digital data storage device, such as a USB stick, hard disk, CD-ROM, SD card, or SSD card (or SSD drive / SSD hard disk).The computer program does not necessarily have to be stored on such a computer-readable storage medium in order to be made available to the motor vehicle, but can also be obtained externally via the Internet or in some other way.The description above with reference to the method, the control device, the computer program and the motor vehicle applies analogously also to the computer-readable medium and vice versa.An optional embodiment will be described below with reference to FIGS. 1 and 2. FIG. 1 schematically shows a motor vehicle having a control device according to the disclosure for operating a battery-electric motor vehicle after an accident situation, and FIG. 2 schematically shows a flow diagram of a method according to the disclosure for controlling an operation of the motor vehicle.The motor vehicle 1 according to an optional embodiment, which is only schematically illustrated in FIG. 1, has the disclosed control device 2. Furthermore, motor vehicle 1 has a high-voltage accumulator 4. Electrical energy can be provided for the high-voltage components of the high-voltage system via the high-voltage accumulator 4. In addition, a measuring device 3 can be provided. The measuring device can comprise an insulation monitoring device and / or an insulation monitor. The control device 2 is configured to execute the method V, described in detail below also with reference to FIG. 2, for controlling an operation of a battery-electric motor vehicle 1 after a crash situation. In a first step S 1, the method comprises all-pole disconnection of the high-voltage accumulator 4 from the high-voltage system after the accident situation. In a further step S 2, it is provided to record a remaining voltage on a Y path of the high-voltage system via a state-dependent measuring device 3 after disconnection of the high-voltage accumulator 4. The measuring device 3 has an active and an inactive state. In addition, in a further step S 3, the measuring device 3 is switched to the active state and couples it to the Y path in order to actively reduce the detected stress remaining in the Y path. For this purpose, the measuring device 3 can be transferred into the active state when the high-voltage accumulator is disconnected from the high-voltage system. The active state of the measuring device can be understood here in such a way that a voltage measurement or insulation resistance measurement is not necessarily also to be carried out in this active state, so that switching of one or more switchable elements of the measuring device takes place, as a result of which the total insulation resistance is reduced for the time period of the active state.Furthermore, it can be provided that the measuring device 3 comprises an insulation monitoring device and / or an insulation monitor. Via an active state of the measuring device 3, the remaining voltage can be actively dissipated via the latter. It is provided that the reduction of the voltage comprises a discharge of Y capacitors of the high-voltage components.Furthermore, the coupling of the measuring device 3 comprises coupling it to the high-voltage negative side of the Y path. The isolation monitor may also assume various positions or states depending on the current parameters and the specific system requirements. In normal operation of the insulation monitor, the high-voltage system is in a normal operating state and the insulation monitor continuously monitors the insulation integrity in order to ensure that no insulation faults are present. If a potential insulation fault or a reduction in the insulation resistances is present in the high-voltage system, the insulation monitor can change to a warning state. In this position, a warning signal can be provided / output. In the presence of a severe insulation fault or a hazardous reduction in insulation integrity, the insulation monitor can trigger a shutdown of the high-voltage system. In this state, the connection between the high-voltage accumulator and the high-voltage components is completely interrupted in order to ensure safety. The RF components are then discharged according to the disclosure.Furthermore, the disconnection of the high-voltage system from the high-voltage accumulator 4 can take place via controllable switching elements and a monitoring of the switching elements can be provided via a switching element adhesion detection. The switching elements can be designed as contactors. The voltage and the current can be provided from the high-voltage accumulator 4 to the high-voltage system and the high-voltage components via the contactors. A high-voltage component can comprise the drive(s). The contactors can be controlled via the control device 2. It can be provided that the switching elements have at least one resistance element bridging the switching element. The resistance element may be formed as a single resistance element or cascade of resistors. Contactor sticking detection can be carried out.List of reference characters1 Motor vehicle 2 Control device 3 Measuring device 4 High-voltage accumulator V Method S 1-S 3 Method stepsReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 2020 / 0127469A1

[0004]

Claims

Control device (2) for operating a battery-electric motor vehicle (1) after an accident situation, wherein the control device (2) is designed to: - disconnect a high-voltage accumulator (4) of the motor vehicle (1) after the accident situation from a high-voltage system comprising high-voltage components in all poles; - after the disconnection of the high-voltage accumulator (4) via a measuring device (3) to record a remaining voltage on a Y section of the high-voltage system as a function of the state of the measuring device (3), wherein the measuring device (3) has an active and an inactive state, characterized in that - the control device (2) is designed to switch the measuring device (3) into the active state and to couple it to the Y section in order to actively reduce the recorded voltage remaining in the Y section.Control device (2) according to the preceding claim, characterized in that the measuring device (3) comprises an insulation monitoring device and / or an insulation monitor.Control device (2) according to at least one of the preceding claims, characterized in that the reduction of the voltage comprises discharging Y capacitors of the high-voltage components.Control device (2) according to at least one of the preceding claims, characterized in that the coupling of the measuring device (3) comprises coupling the latter to the high-voltage negative side of the Y path.Control device (2) according to at least one of the preceding claims, characterized in that the disconnection of the high-voltage system from the high-voltage accumulator (4) takes place via controllable switching elements and monitoring of the switching elements is provided via switching element adhesion detection.Control device (2) according to the immediately preceding claim, characterized in that the switching elements have at least one resistance element bridging the switching element.Motor vehicle, characterized in that the motor vehicle comprises the control device according to one of Claims 1 to 6.Method (V) for controlling operation of a battery-electric motor vehicle (1) after a crash situation, wherein the motor vehicle (1) has a high-voltage accumulator (4) and a high-voltage system having high-voltage components, the method comprising: - all-pole disconnection (S1) of the high-voltage accumulator (4) from the high-voltage system after the crash situation; - detecting (S2) a remaining voltage on a Y path of the high-voltage system via a state-dependent measuring device (3) after disconnection of the high-voltage accumulator (4), wherein the measuring device (3) has an active state and an inactive state, - switching the measuring device (3) into the active state and coupling it to the Y path in order to actively reduce the detected voltage remaining in the Y path.A computer program, characterized in that the computer program comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method according to claim 8.A computer readable medium, characterized in that the computer readable medium comprises instructions which, when the instructions are executed by a computer, cause the computer to carry out the method of claim 8.

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