Method for operating a motor vehicle for a predetermined period of time after deactivating a high-voltage battery of the motor vehicle and motor vehicle with a control unit designed to carry out such a method

Abstract

Method for operating a motor vehicle (10) for a predetermined period of time after deactivating a high-voltage battery (34) of the motor vehicle (10), wherein the motor vehicle (10) comprises: - a high-voltage electrical system (30) with an electric drive motor (31) and the high-voltage battery (34); - a low-voltage vehicle electrical system (40) with a starter battery (41) and low-voltage consumers (42), wherein the starter battery (41) is designed to supply the low-voltage consumers (42) with electrical energy; and - a DC-DC converter (50) via which the high-voltage vehicle electrical system (30) is coupled to the low-voltage vehicle electrical system (40); characterized in that the high-voltage on-board network (30) has an inverter (33) which can be controlled by an engine control device (32) and which is coupled to the electric drive machine (31), wherein the engine control device (32) is designed to predetermine at least one electrical variable of the electric drive machine (31) provided by the inverter (33) and to limit it to a maximum value, wherein the motor vehicle has a charging device (60) coupled to the high-voltage vehicle electrical system (30) with a charging coil (61) which is designed such that a primary voltage can be induced in the charging coil (61) during a journey of the motor vehicle (10) on a charging line (12) which has at least charging sections (14) designed for contactless charging, and a converter (63) which can be controlled by a converter control device (62), wherein the converter control device (62) is designed to predetermine at least one operating parameter to the converter (63), and the converter (63) is designed, depending on the at least one operating parameter, to convert the induced primary voltage into a secondary voltage in a predefined secondary voltage range, which ranges from a predefined minimum voltage to a predefined maximum voltage, and to provide it to the high-voltage vehicle electrical system (30); comprising the following method steps: - detecting the deactivation of the high-voltage battery (34) while the motor vehicle (10) is traveling on the charging road (12) (S1); - Providing the secondary voltage in the high-voltage vehicle electrical system (30) which is above the predetermined minimum voltage of the secondary voltage range and a tertiary voltage in the low-voltage vehicle electrical system (40) which is above a predetermined minimum voltage of the tertiary voltage, by limiting by means of the engine control device (32) the at least one electrical variable provided to the electric drive machine (31) by the inverter (33) to a predetermined emergency running maximum value which is smaller than the predetermined maximum value (S2).

Description

[0001] The invention relates to a method for operating a motor vehicle for a predetermined period of time after deactivating a high-voltage battery of the motor vehicle and to a motor vehicle having a control unit designed to carry out such a method.

[0002] In motor vehicles that include a high-voltage battery for supplying energy to the vehicle's electric drive unit, the high-voltage battery is deactivated if a fault occurs in the high-voltage battery, for example, due to a detected overvoltage or undervoltage, a temperature increase, or a fault in the high-voltage battery's electronics. For this purpose, the high-voltage battery is typically disconnected from the vehicle's high-voltage electrical system using appropriate switches.

[0003] DE 103 04 764 B3 describes a dual-voltage electrical system integrated into a vehicle's dual-battery electrical system. This dual-voltage electrical system uses two conventional vehicle batteries connected in series. This provides a higher supply voltage for the electrical system for high-power consumers.

[0004] DE 10 2015 008 005 A1 describes a method for operating a motor vehicle, wherein a first electrical system comprises a first battery and a generator, and a second electrical system comprises a second battery. Electrical power from the first battery and the generator can be transferred to the second electrical system via a DC / DC converter by means of voltage conversion by the DC / DC converter.

[0005] The generic document DE 10 2016 216 664 A1 shows a method for determining the functional reliability of a battery, in particular a low-voltage battery of an at least partially electrically powered vehicle, which is subjected to a test pulse.

[0006] Furthermore, in connection with charging options for high-voltage batteries of electrically powered motor vehicles, so-called wireless charging lanes are proposed, i.e. charging lanes for the contactless charging of high-voltage batteries on motor vehicles while the motor vehicle is traveling on such a charging lane. In this context, DE 10 2015 004 701 A1 describes a vehicle that has a charging device for receiving energy from an external charging station integrated into a road. The transfer of energy from this external charging station to the charging device should take place quickly and while the motor vehicle is in operation. The charging device is therefore designed to receive the energy as a power pulse and to initially store the energy in an additional storage device in an electrochemical accumulator. The energy is then transferred from the additional storage device to the accumulator.Such a power pulse can range from, for example, one second to, for example, ten minutes.

[0007] DE 10 2015 121 111 A1 discloses a device for charging an electric road vehicle. The device is designed to be recessed into a roadway and comprises an electromagnetic transmitting coil for generating an electric field such that an electrical voltage is induced in an electromagnetic receiving coil of the road vehicle when the road vehicle travels along the roadway.

[0008] The described disconnection of a defective high-voltage battery from the motor vehicle's high-voltage electrical system results in an immediate loss of propulsion, particularly in purely electrically powered vehicles. During a coasting phase of the motor vehicle caused by the immediate loss of propulsion, an electric steering system, an electric brake, and other relevant driving systems are generally supplied with power from a 12-volt battery, the so-called starter battery of the motor vehicle, until some of the energy content of the starter battery is consumed. However, this may, under certain circumstances, result in the motor vehicle being parked on a busy road, such as a highway.Furthermore, particularly in highly automated motor vehicles, such an emergency situation may result in a situation in which the vehicle's occupants are no longer actively involved in the driving or parking process, for example, because a piloted emergency stop is performed. In such an emergency stop, the vehicle may, for example, be brought to a standstill at a current position immediately after the defective high-voltage battery is disconnected from the high-voltage on-board electrical system, i.e., it may be stopped on a busy road onto which the vehicle was traveling before the defective high-voltage battery was discovered. This poses a potential danger to the vehicle's occupants and other road users.

[0009] It is the object of the invention to provide a solution with which traffic safety for a motor vehicle driving on a charging road can be increased after deactivation of a high-voltage battery of the motor vehicle.

[0010] This object is achieved by a method for operating a motor vehicle for a predetermined period of time after deactivating a high-voltage battery of the motor vehicle, as well as by a motor vehicle with a control unit configured to carry out such a method, according to the independent patent claims. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the dependent claims, the following description, and the figures.

[0011] The invention is based on the finding that road safety for a motor vehicle whose high-voltage battery has been deactivated and which is driving on a charging lane can be increased by enabling continued operation of the motor vehicle for a predetermined period of time after deactivation of the high-voltage battery, for example to enable safe parking of the motor vehicle in the area of ​​a nearby parking bay, on a hard shoulder of the charging lane or after leaving the charging lane via a nearby exit.

[0012] The method according to the invention for operating a motor vehicle for a predetermined period of time after deactivating a high-voltage battery of the motor vehicle is designed for a motor vehicle as described below: The motor vehicle has a high-voltage electrical system with an electric drive motor, an inverter controlled by an engine control unit, and a high-voltage battery. The high-voltage battery is coupled to the inverter and designed to supply the electric drive motor with electrical energy. An inverter is an electrical device that can convert direct voltage into alternating voltage, i.e., direct current into alternating current. For example, the inverter converts the direct voltage provided by the high-voltage electrical system into the alternating voltage required to drive the electric drive motor.The inverter, which can be controlled by the engine control unit, is coupled to the electric drive motor. The engine control unit is designed to specify at least one electrical variable provided by the inverter to the electric drive motor and to limit it to a maximum value. This provided electrical variable can, for example, be a maximum power of the electric drive motor. The corresponding maximum power of the electric drive motor is therefore the maximum power that can be made available to the electric drive motor to drive the motor vehicle.

[0013] The motor vehicle also has a low-voltage electrical system with a starter battery and low-voltage consumers. The starter battery is designed to supply the low-voltage consumers with electrical energy. These low-voltage consumers include, for example, the electric steering system, electric brakes, a turn signal system, a radio, or seat heating. The starter battery is the energy storage device in the motor vehicle, typically referred to as a 12-volt battery and is usually also present in electrically powered vehicles to supply a second electrical system to back up the high-voltage electrical system.

[0014] The motor vehicle also has a DC / DC converter, which connects the high-voltage electrical system to the low-voltage electrical system. The DC / DC converter, typically referred to as a DC / DC converter, is designed to convert a DC voltage applied to an input of the DC / DC converter into a DC voltage with a higher, lower, or inverted voltage level. The DC / DC converter galvanically isolates the high-voltage electrical system from the low-voltage electrical system.

[0015] The motor vehicle further comprises a charging device coupled to the high-voltage vehicle electrical system. The charging device comprises a charging coil designed such that a primary voltage can be induced in the charging coil while the motor vehicle is traveling on a charging lane that has at least charging sections designed for contactless charging. The charging lane is, for example, a so-called wireless charging lane (WCL), a frequently discussed concept for contactless charging of high-voltage batteries of motor vehicles while such motor vehicles are in operation. The charging device also comprises a converter controllable by a converter control device. The converter control device is designed to specify at least one operating parameter, such as a frequency, to the converter.The converter is designed to convert the primary voltage induced by driving on the charging track into a secondary voltage within a predetermined secondary voltage range and to provide it to the high-voltage vehicle electrical system depending on the at least one operating parameter, i.e., for example, depending on the frequency specified for it. The secondary voltage ultimately provided by the charging device to the high-voltage vehicle electrical system thus lies between a predetermined minimum voltage and a predetermined maximum voltage, i.e., the predetermined secondary voltage range extends from the predetermined minimum voltage to the predetermined maximum voltage. The converter is, for example, an AC-to-DC converter that converts the primary voltage present as AC voltage into the secondary voltage present as DC voltage.Typically, this converter is current-controlled, meaning the voltage stabilization within the high-voltage electrical system is achieved by the high-voltage battery. However, using the converter control unit, the current can also be adjusted so that the secondary voltage supplied to the high-voltage electrical system remains within the specified secondary voltage range. This does not require any changes to the converter's hardware; rather, such voltage regulation via the converter is possible using the converter control unit designed for this purpose.

[0016] The method according to the invention comprises the following method steps, which can be executed, for example, by a processor device of a control unit of the motor vehicle, wherein the control unit is coupled to the high-voltage battery, the engine control unit, the starter battery, the converter control unit, and the DC-DC converter: First, a deactivation of the high-voltage battery is detected while the motor vehicle is traveling on the charging station. This deactivation occurs, for example, due to a defect in the high-voltage battery. This defect can be caused by an internal fault in the high-voltage battery, for example, due to overvoltage or undervoltage, excessive temperature within the high-voltage battery, or due to a battery fire.Such internal errors are typically responded to by informing a central control unit in the vehicle and / or control units of consumers within the vehicle of the impending deactivation of the high-voltage battery within a finite fault tolerance period. The corresponding signals are transmitted, for example, via information buses such as FlexRays or CAN connections.

[0017] If the motor vehicle is on the charging route when the deactivation of the high-voltage battery is detected, i.e., on a road that has at least charging sections for contactless charging of the motor vehicle's high-voltage battery, a secondary voltage is provided in the high-voltage vehicle electrical system, which is above the predefined minimum voltage of the secondary voltage range, and a tertiary voltage is provided in the low-voltage vehicle electrical system, which is above a predefined minimum voltage of the tertiary voltage. These respective minimum voltages are provided by the engine control device limiting the at least one electrical variable provided to the electric drive motor by the inverter to a predefined emergency maximum value that is less than the predefined maximum value.For example, the maximum power supplied to the electric drive motor by the inverter can be limited to a specified emergency maximum power, which is lower than the specified maximum power. This ensures that the electric drive motor is supplied with less electrical energy than before the high-voltage battery was deactivated. Without limiting the electrical parameter, such as power, the electric drive motor would continue to draw the same amount of energy from the high-voltage electrical system that it would have drawn if the high-voltage battery had been intact.However, driving the vehicle at the power it was operating at before the high-voltage battery deactivation was detected is not advisable in such an emergency operation, as this could quickly drain the energy of the starter battery, which is actually intended for continued steering and supplying power to the vehicle's brakes. Draining the starter battery by operating the electric drive motor is thus prevented because, for example, the power provided to the electric drive motor is limited to the corresponding maximum emergency operation value by the amount provided by the inverter.This also means that specified low-voltage consumers, such as the vehicle's steering system, remain activated, regardless of whether the secondary voltage for operating the electric drive motor is available in the high-voltage electrical system or not, and can be supplied with energy via the tertiary voltage provided by the starter battery. The vehicle can then continue to be operated at least for the specified period after the high-voltage battery is deactivated and can, for example, be steered to the side of the road and parked there in a controlled manner.

[0018] Limiting the electrical quantity supplied to the electric drive motor is necessary and sensible, since the coupling between the high-voltage on-board power supply and the low-voltage on-board power supply via the DC-DC converter could potentially lead to rapid discharge of the starter battery if the electrical quantity supplied to the electric drive motor is not limited to a lower emergency maximum value than the previously specified maximum value. By providing the secondary voltage and the tertiary voltage as described, the voltage in the high-voltage on-board power supply and the low-voltage on-board power supply can also be stabilized, since both the secondary voltage and the tertiary voltage are limited at least with respect to a lower limit of a respective voltage range, i.e., with respect to respective minimum voltages.

[0019] The invention also includes further developments which result in additional advantages.

[0020] In an advantageous embodiment of the invention, it is provided that the at least one electrical variable specified to the electric drive motor by the inverter, which is limited by the engine control unit to the predetermined maximum emergency operation value, is a power of the electric drive motor limited to an emergency operation maximum power and / or a current gradient of the electric drive motor limited to an emergency operation maximum current gradient. The emergency operation maximum power and the emergency operation maximum current gradient can be selected depending on whether the motor vehicle is currently located on one of the charging sections of the charging lane or between two such charging sections.If the motor vehicle is not currently traveling through a charging section, the high-voltage battery is deactivated and, due to the detected defect, no longer provides sufficient energy to supply the electric drive motor to the motor vehicle's electric drive unit. This means that the high-voltage vehicle electrical system does not have sufficient energy available to operate the electric drive unit as before the high-voltage battery was deactivated, without causing the starter battery of the low-voltage vehicle electrical system to drain more quickly than if only the low-voltage consumers were supplied with electrical energy from the starter battery. While the motor vehicle is between two charging sections, the maximum emergency power and the maximum emergency current gradient could therefore typically be set to 0 watts and 0 amperes per second, respectively.However, if the motor vehicle is currently located above one of the charging sections of the charging lane, this maximum emergency operating value can be selected such that the electric drive motor is supplied with sufficient energy, enabling, for example, acceleration of the motor vehicle using the electric drive motor. The motor vehicle, which has accelerated again in this way, can, for example, approach an emergency stopping bay at the side of the charging lane particularly quickly or, for example, exit a curve in the charging lane to stop the motor vehicle in an area of ​​the charging lane that is more visible to other road users.

[0021] Limiting the current gradient is particularly useful for preventing a vehicle occupant from accelerating sharply after detecting that the high-voltage battery has been deactivated, which would drain a particularly large amount of energy from the high-voltage electrical system and the low-voltage electrical system coupled to it. Furthermore, large currents in a relatively short period of time can lead to instabilities in both the high-voltage electrical system and the low-voltage electrical system. For example, overvoltages can occur, which can lead to a defect in the DC-DC converter or in low-voltage consumers, such as the steering or brakes.Ultimately, by limiting the two electrical variables mentioned, both the maximum power of the electric drive motor and the current per unit time for driving the electric drive motor can be reduced in such a way that reliable and maximum long-lasting continued operation of the low-voltage consumers in the low-voltage on-board network, such as an electric steering system or an electric brake, is enabled by means of the energy supply of the low-voltage on-board network by the starter battery.

[0022] Another particularly advantageous embodiment of the invention provides that the provided secondary voltage is below the predetermined maximum voltage of the secondary voltage range, and the tertiary voltage is below a predetermined maximum voltage of the tertiary voltage. This is achieved by modifying the at least one operating parameter using the converter control device such that, when converting the induced primary voltage into the secondary voltage in the high-voltage vehicle electrical system, the converter provides the maximum power that can be absorbed by the high-voltage vehicle electrical system within a predetermined time interval. The upper limit of the secondary voltage range and a corresponding tertiary voltage range can thus be determined by appropriately controlling the converter control device.For this purpose, the converter control unit operates the converter in voltage-sensitive mode to ultimately stabilize the energy supply from the charging station to the high-voltage vehicle electrical system, which in turn is coupled to the low-voltage vehicle electrical system, i.e., to keep it below the respective specified maximum voltages. The maximum voltage of the secondary voltage range is selected such that the secondary voltage provided to the high-voltage vehicle electrical system by the converter is sufficient to operate the electric drive motor while the vehicle is traveling on one of the charging sections of the charging station. At the same time, however, damage to low-voltage consumers in the low-voltage vehicle electrical system due to an influence on the tertiary voltage by the primary voltage induced in the charging coil is prevented, since both the secondary voltage and the tertiary voltage are limited to the respective specified maximum voltage.Because the high-voltage battery is deactivated, the energy provided by the charging station can no longer be stored in the high-voltage battery. Any energy fed into the high-voltage electrical system via the charging device must therefore be consumed, for example, as power to drive the electric drive motor or high-voltage consumers included in the high-voltage electrical system, such as the vehicle's energy-intensive air conditioning system, and absorbed by the corresponding lines in the high-voltage electrical system.By limiting the secondary voltage and the tertiary voltage to respective maximum voltage values ​​in combination with the already described limitations of the secondary voltage and the tertiary voltage to values ​​above respective predetermined minimum voltages, a voltage level lying within the respective voltage range of the secondary voltage and the tertiary voltage and thus stable can be achieved in the high-voltage on-board network and in the low-voltage on-board network of the motor vehicle, so that at all times, i.e. also when driving between charging sections of the charging route, the low-voltage consumers, such as the steering and the brakes of the motor vehicle, continue to function and can be supplied with sufficient energy and, in addition, the electric drive motor can be supplied with energy while driving on a charging section.

[0023] In a further embodiment of the invention, it is provided that, in order to provide the secondary voltage and the tertiary voltage, which are each below the respective predetermined maximum voltage, energy recovery is reduced or prevented by operating the motor vehicle in a recuperation mode. The recuperation mode of a motor vehicle is often implemented using so-called regenerative brakes, also known as regenerative brakes. In this case, the regenerative brake recovers kinetic energy as electrical energy when the motor vehicle is braking. This energy is supplied, for example, to the motor vehicle's high-voltage electrical system, resulting in overvoltages or undervoltages compared to when the motor vehicle is operated with the recuperation mode deactivated.These overvoltages or undervoltages can occur, in particular, because the storage of the recovered electrical energy in the deactivated high-voltage battery is not possible. To ensure that the secondary voltage is within the specified secondary voltage range and the tertiary voltage is also within the specified tertiary voltage range, the recuperation mode, i.e., the associated energy recovery, should be at least throttled or even completely deactivated. This can compensate for any resulting lack of braking torque in the vehicle by a corresponding function in a brake control unit for controlling the brakes, so that the deceleration values ​​typically achieved by the vehicle can be achieved even when the recuperation mode is reduced or prevented.

[0024] In a further advantageous embodiment of the invention, it is provided that, in order to provide the secondary voltage and the tertiary voltage, which are each below the respective predetermined maximum voltage, the DC-DC converter limits an electrical battery variable provided by the starter battery, in particular a power and / or a current gradient, to a corresponding predetermined maximum battery variable. Thus, the maximum power or the current gradient of the DC-DC converter for supplying the low-voltage vehicle electrical system is also reduced, again with the aim of achieving stable secondary voltages, i.e., secondary voltages within the predetermined secondary voltage range, and stable tertiary voltages, i.e., tertiary voltages within the predetermined tertiary voltage range.In this case, it is particularly advantageous to select a relatively low power and current gradient in the low-voltage vehicle electrical system compared to operation with a defect-free, functional high-voltage battery. This allows for a particularly long period of operation of the vehicle after the high-voltage battery has been deactivated due to a detected high-voltage battery defect.

[0025] In a further particularly advantageous embodiment of the invention, it is provided that the low-voltage consumers and the high-voltage consumers included in the high-voltage vehicle electrical system are each assigned to a first or a second priority class. In order to provide the secondary voltage and the tertiary voltage, which are each above the respective predetermined minimum voltage, the low-voltage consumers and the high-voltage consumers of the first priority class continue to be supplied with electrical energy after the shutdown of the high-voltage battery has been detected, and the low-voltage consumers and the high-voltage consumers of the second priority class are deactivated. The low-voltage consumers and the high-voltage consumers of the high-voltage vehicle electrical system are thus assigned to two different priority classes. These priority classes are referred to as the first priority class and the second priority class.The first priority class includes, for example, low-voltage and high-voltage consumers designed to contribute to the driving operation of the motor vehicle. Examples of such first-priority class consumers include the vehicle's steering and brakes, as well as hazard warning lights and vehicle dynamics control. Low-voltage and high-voltage consumers in the second priority class include, for example, comfort functions such as seat heating, a radio, or a crosswind compensation device. Other second-priority class consumers include, for example, an electric air conditioning compressor or an on-board charger (OBC), which enables power charging processes and direct current charging communication for charging the high-voltage battery.To ensure that the specified operating period for the motor vehicle after deactivation of the high-voltage battery lasts as long as possible, energy consumption in the motor vehicle during this operation should be kept particularly low. Therefore, only those low-voltage and high-voltage consumers that are assigned to the first priority class and thus contribute to the operation of the motor vehicle should continue to be supplied with electrical energy.

[0026] A further embodiment of the invention provides that, in order to provide the secondary voltage and the tertiary voltage, which are each above the respective predetermined minimum voltage, the low-voltage consumers, which continue to be supplied with electrical energy after the high-voltage battery has been detected to be switched off, are placed in a standby mode if the motor vehicle is not currently traveling over a charging section. At times when no primary voltage is indicated by the charging coil due to traveling over a charging section, all components of the motor vehicle that are not switched off are thus operated in a standby mode, i.e., in the so-called standby mode.This standby mode ensures that the voltage supply to the low-voltage electrical system, provided by the high-voltage electrical system independently of the starter battery, is maintained for a longer period than if the activity of the corresponding consumers remains unchanged. However, if the motor vehicle is currently driving through a charging section or, for example, through a charging lane that consists of a single charging section extending the length of the charging lane and thus does not include any sections that do not constitute a charging section, the low-voltage consumers that continue to be supplied with electrical energy after the high-voltage battery is switched off remain, for example, in an active mode and are not switched to standby mode.By placing the low-voltage consumers in standby mode, a particularly long period of time after deactivation of the high-voltage battery for operating the vehicle is also made possible, since energy is saved in the low-voltage vehicle electrical system during journeys over sections of the charging route that are not charging sections.

[0027] In a further embodiment of the invention, it is provided that, in order to provide the secondary voltage and the tertiary voltage, which are each above the respective predetermined minimum voltage, the low-voltage consumers and the high-voltage consumers are switched off, switched on, or supplied with reduced electrical energy depending on the tertiary voltage and the secondary voltage according to a predetermined functional cascade after the high-voltage battery has been switched off, depending on the tertiary voltage and the secondary voltage. Thus, depending on the current secondary voltage and tertiary voltage, individual low-voltage consumers and high-voltage consumers can be switched on, remain activated at least in an energy-saving mode, or switched off in a predetermined order specified by the so-called functional cascade.This makes it possible, for example, for the respective consumers in the high-voltage electrical system and / or the low-voltage electrical system to switch off or at least reduce their electrical output in the event of an undervoltage in the high-voltage electrical system and / or the low-voltage electrical system. Reducing the electrical output is particularly useful for high-voltage consumers, as it ensures that the power consumption of the high-voltage consumers does not lead to unstable conditions in the high-voltage section. In addition, at high voltages in the high-voltage electrical system, individual inverters and converters can be controlled in such a way that they draw more power from the high-voltage electrical system than at lower voltages. In such situations with high voltages in the high-voltage electrical system, second-priority consumers, for example comfort consumers, can also be switched on in order to stabilize the secondary voltage in the high-voltage electrical system.Such overvoltages in the high-voltage electrical system can occur, for example, when driving through a charging section suddenly provides more power to operate high-voltage consumers or even low-voltage consumers in the high-voltage electrical system. This can, for example, provide more electrical power to the vehicle's drive engine, but can also reactivate comfort functions, such as crosswind compensation, that were previously deactivated to save energy.

[0028] In a further particularly advantageous embodiment of the invention, it is provided that if the motor vehicle is not traveling on one of the charging sections of the charging lane, the motor vehicle is piloted to the nearest charging section. The motor vehicle is thus put into a so-called sailing mode; if the motor vehicle's electric drive motor is not currently supplied with energy, the motor vehicle "sails" to the location of the nearest charging section by means of appropriate control commands to the motor vehicle's steering system. There, the motor vehicle is then at least temporarily supplied with energy from the charging lane, so that the motor vehicle can be subjected to acceleration, at least temporarily. As soon as the motor vehicle has reached the nearest charging section, the motor vehicle's electric drive motor can be supplied with energy for as long as the motor vehicle travels through the charging section.As soon as it leaves the charging section, the vehicle "sails" to the nearest charging section, meaning it is piloted to reach the nearest charging section where acceleration can be applied again. The vehicle is therefore designed to always reach the nearest charging section in piloted driving mode.

[0029] Alternatively, or in addition to piloted control of the motor vehicle from one charging section to the nearest charging section, appropriate instructions can be displayed on a corresponding display device inside the vehicle to a driver manually controlling the motor vehicle. These instructions can, for example, indicate a lane change or rolling in the current lane to the nearest charging section.

[0030] However, the motor vehicle should not be operated in such a way that it continues to drive indefinitely despite the high-voltage battery being detected as disconnected. The described procedural steps are intended solely to ensure that the motor vehicle continues to operate for the specified period, for example, by reaching the nearest parking bay, hard shoulder, or exit, in order to prevent the motor vehicle from suddenly breaking down on a busy road or blocking the charging lane for other motor vehicles.

[0031] The invention further comprises a motor vehicle having a high-voltage electrical system with an electric drive motor, an inverter which can be controlled by an engine control device and is coupled to the electric drive motor, wherein the engine control device is designed to predetermine at least one electrical variable of the electric drive motor provided by the inverter and to limit it to a maximum value, and the high-voltage battery. The motor vehicle further comprises a low-voltage electrical system with a starter battery and low-voltage consumers, wherein the starter battery is designed to supply the low-voltage consumers with electrical energy. Furthermore, the motor vehicle according to the invention comprises a DC-DC converter, via which the high-voltage electrical system is coupled to the low-voltage electrical system, and a charging device coupled to the high-voltage electrical system and having a charging coil.The charging coil is designed such that a primary voltage can be induced in the charging coil while the motor vehicle is traveling on a charging line that has at least charging sections designed for contactless charging. Furthermore, the charging device of the motor vehicle comprises a converter controllable by a converter control device, wherein the converter control device is designed to specify at least one operating parameter to the converter, and the converter is designed, depending on the at least one operating parameter, to convert the induced primary voltage into a secondary voltage within a predetermined secondary voltage range, which extends from a predetermined minimum voltage to a predetermined maximum voltage, and to provide it to the high-voltage vehicle electrical system.

[0032] The motor vehicle further comprises a control unit having a processor device. The control unit is coupled to the high-voltage battery, the engine control device, the starter battery, the converter control device, and the DC-DC converter. The processor device is configured to detect deactivation of the high-voltage battery while the motor vehicle is traveling on the charging station and to provide the secondary voltage in the high-voltage vehicle electrical system that is above the minimum voltage of the secondary voltage range and a tertiary voltage in the low-voltage vehicle electrical system that is above a minimum voltage of the tertiary voltage. By appropriately controlling the engine control device by the control unit, the at least one electrical variable specified by the inverter for the electric drive motor can be limited to a specified emergency maximum value that deviates from the specified maximum value.The control unit, which has the processor device, is thus designed overall to carry out an embodiment of the method according to the invention. The preferred embodiments presented in connection with the method according to the invention and their advantages apply accordingly, where applicable, to the motor vehicle according to the invention.

[0033] The invention also includes the control unit for the motor vehicle. This control unit has the processor device configured to carry out an embodiment of the method according to the invention. For this purpose, the processor device can have at least one microprocessor and / or one microcontroller. Furthermore, the processor device can have program code configured to carry out the embodiment of the method according to the invention when executed by the processor device. The program code can be stored in a data memory of the processor device.

[0034] The invention also includes combinations of the features of the described embodiments.

[0035] An embodiment of the invention is described below. It shows: Fig. 1 a schematic representation of a motor vehicle on a loading lane with loading sections; Fig. 2 a schematic representation of a motor vehicle, comprising a high-voltage electrical system, a low-voltage electrical system and a charging device; and Fig. 3 shows a schematic representation of a signal flow graph for a method for operating a motor vehicle for a predetermined period of time after deactivation of a high-voltage battery of the motor vehicle.

[0036] The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass combinations of the features of the embodiment other than those illustrated. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

[0037] In the figures, the same reference symbols designate elements with the same function.

[0038] In Fig. 1 shows a motor vehicle 10 traveling along a charging lane 12. This charging lane 12 has charging sections 14 designed for contactless charging. The motor vehicle 10 comprises a control unit 20, a high-voltage electrical system 30, a charging device 60, and a low-voltage electrical system 40. The low-voltage electrical system 40 is electrically coupled to the high-voltage electrical system 30 via a DC-DC converter 50. The charging device 60 is also electrically coupled to the high-voltage electrical system 30. The control unit 20 is designed to control individual components of the high-voltage electrical system 30, the charging device 60, the low-voltage electrical system 40, and the DC-DC converter 50.

[0039] In Fig. 2 shows a detailed outline of the individual components of the motor vehicle 10. The high-voltage electrical system 30 comprises an electric drive motor 31, which is designed to supply a high-voltage battery 34 of the high-voltage electrical system 30 with electrical energy. Furthermore, the high-voltage electrical system 30 comprises an inverter 33, which can be controlled by an engine control unit 32 and is coupled to the electric drive motor 31. The engine control unit 32 is designed to specify at least one electrical variable provided by the inverter 33, in particular a power and / or a current gradient, of the electric drive motor 31 and to limit it to a maximum value, that is to say in particular to a maximum power and / or a maximum current gradient. The high-voltage electrical system 30 also comprises, for example, two further high-voltage consumers 35, such as an energy-intensive air conditioning system and a heater.

[0040] The low-voltage electrical system 40 of the motor vehicle 10 comprises a starter battery 41, which is, for example, a 12-volt battery for a motor vehicle 10, and low-voltage consumers 42. The starter battery 41 is designed to supply the low-voltage consumers 42 with electrical energy. The low-voltage consumers 42 include, for example, a steering system 42a of the motor vehicle 10 or brakes of the motor vehicle 10. Such low-voltage consumers 42 are relevant for the operation of the motor vehicle 10 and can thus be assigned to a first priority class of low-voltage consumers 42 and / or high-voltage consumers 35. The second low-voltage consumer 42 outlined here is a seat heater 42b of the motor vehicle 10. This low-voltage consumer 42 is a so-called comfort consumer and thus a low-voltage consumer 42 of a second priority class of consumers of the motor vehicle 10.

[0041] The high-voltage electrical system 30 is electrically coupled to the low-voltage electrical system 40 via the DC-DC converter 50. However, the high-voltage electrical system 30 is also electrically coupled to the charging device 60. The charging device 60 comprises a charging coil 61 designed to induce a primary voltage in the charging coil 61 while the motor vehicle 10 is traveling on the charging line 12, which has at least charging sections 14 designed for contactless charging. The charging device 60 also comprises a converter 63 that can be controlled by a converter control device 62. The converter control device 62 is designed to specify at least one operating parameter for the converter.The converter 63 is further designed to convert the induced primary voltage into a secondary voltage in a predetermined secondary voltage range, which extends from a predetermined minimum voltage to a predetermined maximum voltage, and to provide it to the high-voltage vehicle electrical system 30, depending on the at least one operating parameter.

[0042] The control unit 20 has a processor device 21 and is coupled to the high-voltage battery 34, the engine control device 32, the starter battery 41, the converter control device 62, and the DC-DC converter 50. The processor device 21 is designed to carry out a method for operating the motor vehicle 10 for a predetermined period of time after deactivating the high-voltage battery 34 of the motor vehicle 10.

[0043] In Fig.3, the individual method steps of this method for operating the motor vehicle 10 for a predetermined period of time after deactivation of the high-voltage battery 34 of the motor vehicle 10 are shown as a signal flow graph. In a first step S1, a deactivation of the high-voltage battery 34 is determined while the motor vehicle 10 is traveling on the charging station 12. In a next step S2, the secondary voltage is provided in the high-voltage electrical system 30, which is above the predetermined minimum voltage of the secondary voltage range, and a tertiary voltage is provided in the low-voltage electrical system 40, which is above a predetermined minimum voltage of the tertiary voltage.This is achieved by limiting, by means of the motor control device 32, at least one electrical variable provided to the electric drive motor 31 by the inverter 33, that is to say, for example, the power and / or the current gradient of the electric drive motor 31, to a predefined emergency running maximum value that is less than the predefined maximum value. Thus, for example, the maximum power of the electric drive motor 31 can be limited to a predefined emergency running maximum power that is less than the predefined maximum power. Alternatively or additionally, the maximum current gradient that can occur in the electric drive motor 31, for example for accelerating the motor vehicle 10, can be reduced to a predefined emergency running maximum current gradient that is less than the predefined maximum current gradient.With this step S2, the minimum voltage of the secondary voltage and the corresponding minimum voltage for the tertiary voltage are determined.

[0044] In further additional method steps S3 to S5, it can be achieved that the provided secondary voltage is below the predetermined maximum voltage of the secondary voltage range and the tertiary voltage is below a predetermined maximum voltage of the tertiary voltage. This is possible by modifying the at least one operating parameter in a step S3 using the converter control device 62 such that the converter 63, when converting the induced primary voltage into the secondary voltage in the high-voltage vehicle electrical system 30, provides the maximum power that can be absorbed by the high-voltage vehicle electrical system 30 in a predetermined time interval. Alternatively or additionally, in a step S4, energy recovery can be reduced or prevented by operating the motor vehicle 10 in a recuperation mode.Alternatively or additionally, in a step S5 of the DC-DC converter 50, an electrical battery size provided by the starter battery 41, in particular a power and / or a current gradient, can be limited to a corresponding predetermined maximum battery size.

[0045] Additionally or alternatively, the operating state of the low-voltage consumers 42 and the high-voltage consumers 35 is influenced by method steps S8 to S10. These method steps for influencing the operating state of the low-voltage consumers 42 and the high-voltage consumers 35 also ensure that the secondary voltage and the tertiary voltage, each of which is above the respective predetermined minimum voltage, are provided. In step S8, the low-voltage consumers 42 and the high-voltage consumers 35 of the first priority class continue to be supplied with electrical energy after the deactivation of the high-voltage battery 34 is detected, and the low-voltage consumers 42 and the high-voltage consumers 35 of the second priority class are deactivated.In addition, in a step S9, the low-voltage consumers 42, which continue to be supplied with electrical energy after the high-voltage battery 34 has been switched off, can be put into a ready mode, i.e. into a standby mode, if the motor vehicle 10 is not currently traveling over a charging section 14.

[0046] In step S10, alternatively or additionally, the low-voltage consumers 42 and the high-voltage consumers 35 are switched off, switched on and continue to be supplied with reduced electrical energy, depending on the tertiary voltage and the secondary voltage, in accordance with a predetermined functional cascade after the deactivation of the high-voltage battery 34 has been determined.

[0047] If the motor vehicle 10 is not traveling on one of the charging sections 14 of the charging lane 12, the motor vehicle 10 can be piloted to the nearest charging section 14. There, the motor vehicle 10 can be subjected to acceleration, at least temporarily, since the electric drive motor 31 can be supplied with energy there, at least temporarily.

[0048] Overall, the examples show how, with the method for operating the motor vehicle 10 for a predetermined period of time after deactivating the high-voltage battery 34 of the motor vehicle 10, it is possible to continue to control the motor vehicle 10 at least by means of the steering 42a and to drive it by means of energy supply to the electric drive motor 31 while driving through one of the charging sections 14, in order to ultimately reach the nearest parking bay, a hard shoulder of the charging lane 12, or the nearest exit from the charging lane 12 with the motor vehicle 10. There, the motor vehicle 10 can be stopped in a controlled manner and, if necessary, with the intervention of an occupant of the motor vehicle 10. This is possible because a relatively stable voltage is realized in both the high-voltage on-board electrical system 30 and the low-voltage on-board electrical system 40, specifically with the aid of method steps S2 to S10.This means that the secondary voltage and the tertiary voltage each lie within specified voltage ranges between the respective minimum voltages and maximum voltages.

[0049] The method therefore comprises, when the motor vehicle 10 travels on one of the loading sections 14, at least some of the following method steps: - Switching off comfort consumers and consumers without function while driving (S8); - switching the converter 63 to a voltage-sensitive operation in order to try to stabilize the secondary voltage using an energy supply from the charging section 14 (S3); - reducing the maximum permissible electrical power for the electric drive machines 31 by the electric drive machine 31 or by inverters and / or AC / DC converters responsible for controlling the electric drive machine 31, i.e. the inverter 33 (S2); - limiting the maximum current gradient for the electric drive motor 31, since the high-voltage electrical system 30 without the high-voltage battery 34 must be treated more sensitively in terms of control technology (because rapid current gradients lead to high voltage gradients due to finite capacities and their limited stabilization options compared to the impedance of the high-voltage battery 34) (S2); - the significant reduction or complete prevention of recuperation of the electric drive motor 31, whereby the voltage stability is further increased (it is advantageous in this case to compensate for missing braking torques by a corresponding function in a brake control unit, so that normal deceleration values ​​of the motor vehicle 10 can be achieved) (S4); - reducing the current gradients and / or the maximum power of the DC-DC converter 50 for supplying the low-voltage vehicle electrical system 40 in order to achieve a stable high-voltage intermediate circuit (S5); - the introduction of specific functional cascades, whereby a modification of a voltage derating in components, i.e. in consumers of the motor vehicle 10, is activated (because in the case of undervoltages, the low-voltage consumers 42 and / or the high-voltage consumers 35 switch off early or reduce their electrical power accordingly; moreover, in the case of high voltages in the high-voltage intermediate circuit, the inverters and converters 63 can draw more power from the high-voltage on-board network 30; however, comfort consumers can also be switched on in these cases in order to further stabilize the high-voltage intermediate circuit) (S10).

[0050] The method further comprises, if the motor vehicle 10 is not traveling on one of the loading sections 14, in addition to or alternatively to the aforementioned method steps, at least some of the following method steps: - All components, i.e. all low-voltage consumers 42, remain in standby mode, ensured by the energy supply of the low-voltage consumers 42 by means of the starter battery 41 (S9), which is independent of the high-voltage on-board network 30; - Attempts by the motor vehicle 10 to reach the next loading section 14 (either piloted or by giving appropriate instructions to the occupants, including changing lanes and / or simply “rolling” to the next loading section 14).

Claims

[1] Method for operating a motor vehicle (10) for a predetermined period of time after deactivating a high-voltage battery (34) of the motor vehicle (10), wherein the motor vehicle (10) comprises: - a high-voltage electrical system (30) with an electric drive motor (31) and the high-voltage battery (34); - a low-voltage vehicle electrical system (40) with a starter battery (41) and low-voltage consumers (42), wherein the starter battery (41) is designed to supply the low-voltage consumers (42) with electrical energy; and - a DC-DC converter (50) via which the high-voltage vehicle electrical system (30) is coupled to the low-voltage vehicle electrical system (40); characterized by , that the high-voltage on-board network (30) has an inverter (33) which can be controlled by an engine control device (32) and which is coupled to the electric drive machine (31), wherein the engine control device (32) is designed to predetermine at least one electrical variable of the electric drive machine (31) provided by the inverter (33) and to limit it to a maximum value, wherein the motor vehicle has a charging device (60) coupled to the high-voltage vehicle electrical system (30) with a charging coil (61) which is designed such that a primary voltage can be induced in the charging coil (61) during a journey of the motor vehicle (10) on a charging line (12) which has at least charging sections (14) designed for contactless charging, and a converter (63) which can be controlled by a converter control device (62), wherein the converter control device (62) is designed to predetermine at least one operating parameter to the converter (63), and the converter (63) is designed, depending on the at least one operating parameter, to convert the induced primary voltage into a secondary voltage in a predefined secondary voltage range, which ranges from a predefined minimum voltage to a predefined maximum voltage, and to provide it to the high-voltage vehicle electrical system (30); comprising the following method steps: - detecting the deactivation of the high-voltage battery (34) while the motor vehicle (10) is traveling on the charging road (12) (S1); - Providing the secondary voltage in the high-voltage vehicle electrical system (30) which is above the predetermined minimum voltage of the secondary voltage range and a tertiary voltage in the low-voltage vehicle electrical system (40) which is above a predetermined minimum voltage of the tertiary voltage, by limiting by means of the engine control device (32) the at least one electrical variable provided to the electric drive machine (31) by the inverter (33) to a predetermined emergency running maximum value which is smaller than the predetermined maximum value (S2). [2] Method according to the preceding claim, characterized bythat as the at least one electrical variable which is limited by the engine control device (32) to the predetermined emergency running maximum value and which is predetermined for the electric drive machine (31) by the inverter (33), a power of the electric drive machine (31) is limited to an emergency running maximum power and / or a current gradient of the electric drive machine (31) is limited to an emergency running maximum current gradient. [3] Method according to one of the preceding claims, characterized bythat the secondary voltage provided is below the predetermined maximum voltage of the secondary voltage range and the tertiary voltage is below a predetermined maximum voltage of the tertiary voltage, in that the at least one operating parameter is modified by means of the converter control device (62) such that the converter (63), when converting the induced primary voltage into the secondary voltage in the high-voltage vehicle electrical system (30), provides a maximum of the power that can be absorbed by the high-voltage vehicle electrical system (30) in a predetermined time interval (S3). [4] Method according to the preceding claim, characterized by in that, in order to provide the secondary voltage and the tertiary voltage, which are each below the respective predetermined maximum voltage, energy recovery is reduced or prevented by operating the motor vehicle (10) in a recuperation mode (S4). [5] Method according to one of claims 3 or 4, characterized byin that, in order to provide the secondary voltage and the tertiary voltage, which are each below the respective predetermined maximum voltage, the DC-DC converter (50) limits an electrical battery size provided by the starter battery (41), in particular a power and / or a current gradient, to a corresponding predetermined maximum battery size (S5). [6] Method according to one of the preceding claims, characterized bythat the low-voltage consumers (42) and the high-voltage consumers (35) included in the high-voltage on-board network (30) are each assigned to a first or a second priority class and, in order to provide the secondary voltage and the tertiary voltage, which are each above the respective predetermined minimum voltage, the low-voltage consumers (42) and the high-voltage consumers (35) of the first priority class continue to be supplied with electrical energy after the high-voltage battery (34) has been detected to be switched off and the low-voltage consumers (42) and the high-voltage consumers (35) of the second priority class are deactivated (S8). [7] Method according to the preceding claim, characterized byin that, in order to provide the secondary voltage and the tertiary voltage, which are each above the respective predetermined minimum voltage, the low-voltage consumers (42), which continue to be supplied with electrical energy after the high-voltage battery (34) has been switched off, are put into a standby mode if the motor vehicle (10) is not currently traveling over a charging section (14) (S9). [8] Method according to one of claims 6 or 7, characterized by in that, in order to provide the secondary voltage and the tertiary voltage, which are each above the respective predetermined minimum voltage, the low-voltage consumers (42) and the high-voltage consumers (35) are switched off, switched on or supplied with reduced electrical energy (S10) depending on the tertiary voltage and the secondary voltage after the deactivation of the high-voltage battery (34) has been detected, in accordance with a predetermined functional cascade. [9] Method according to one of the preceding claims, characterized by that, if the motor vehicle (10) is not traveling on one of the loading sections (14) of the loading road (12), the motor vehicle (10) is piloted to the nearest loading section (14). [10] Motor vehicle (10) comprising: - a high-voltage vehicle electrical system (30) with an electric drive motor (31) and a high-voltage battery (34); - a low-voltage vehicle electrical system (40) with a starter battery (41) and low-voltage consumers (42), wherein the starter battery (41) is designed to supply the low-voltage consumers (42) with electrical energy; and - a DC-DC converter (50) via which the high-voltage vehicle electrical system (30) is coupled to the low-voltage vehicle electrical system (40); characterized by , that the high-voltage on-board network (30) has an inverter (33) which can be controlled by an engine control device (32) and which is coupled to the electric drive machine (31), wherein the engine control device (32) is designed to predetermine at least one electrical variable of the electric drive machine (31) provided by the inverter (33) and to limit it to a maximum value, wherein the motor vehicle (10) has a charging device (60) coupled to the high-voltage vehicle electrical system (30) with a charging coil (61) which is designed such that a primary voltage can be induced in the charging coil (61) during a journey of the motor vehicle (10) on a charging line (12) which has at least charging sections (14) designed for contactless charging, and a converter (63) which can be controlled by a converter control device (62), wherein the converter control device (62) is designed to predetermine at least one operating parameter to the converter (63), and the converter (63) is designed, depending on the at least one operating parameter, to convert the induced primary voltage into a secondary voltage in a predefined secondary voltage range which extends from a predefined minimum voltage to a predefined maximum voltage, and to provide it to the high-voltage vehicle electrical system (30); wherein the motor vehicle (10) comprises a control unit (20) which is coupled to the high-voltage battery (34), the engine control device (32), the starter battery (41), the converter control device (62), and the DC-DC converter (50), and comprises a processor device (21) which is designed to detect deactivation of the high-voltage battery (34) while the motor vehicle (10) is traveling on the charging route (12) and to provide the secondary voltage in the high-voltage vehicle electrical system (30) which is above the minimum voltage of the secondary voltage range, and a tertiary voltage in the low-voltage vehicle electrical system (40) which is above a minimum voltage of the tertiary voltage, by means of appropriate control of the engine control device (32) by the control unit (20) limiting the at least one electrical variable specified by the inverter (33) for the electric drive machine (31) to a specified emergency maximum value which deviates from the specified maximum value.

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