Battery management method and battery management system for an on-board electrical system battery of a hybrid motor vehicle

Abstract

Battery management method for an on-board battery (40) of a hybrid motor vehicle (10) with an internal combustion engine (20) and at least one electric machine (30), wherein the internal combustion engine (20) has an exhaust aftertreatment device (21) with at least one electrically heated catalyst (22) and the at least one electric machine (30) can be operated in generator mode to charge the on-board battery (40);wherein the current charge level (SoC_curr) of the on-board battery (40) is continuously monitored and maintained at a required charge level (SoC_req) by means of the electric machine (30), which reliably ensures that the catalyst (22) is electrically heated from the on-board battery (40) to an activation temperature during a subsequent cold start of the internal combustion engine (20), wherein the required charge level (SoC_req) of the on-board battery (40) is continuously determined during operation depending on: - the state of aging (SoH_Cat) of the catalyst (22); - the state of aging (SoH_Bat) of the on-board battery (40) and the ambient temperature (T_exp) of the on-board battery (40) and catalyst (22) expected during the subsequent cold start;wherein the temperatures of the on-board battery (40) and the catalyst (22) expected during a subsequent cold start of the internal combustion engine (20) are estimated on the basis of ambient temperature values ​​at the time of the preceding shutdown of the internal combustion engine (20) or on the basis of an ambient temperature profile over a period of time before the preceding shutdown of the internal combustion engine (20).

Description

[0001] The invention relates to a battery management method and a battery management device for the battery management of an on-board power supply battery of a hybrid motor vehicle with an internal combustion engine with an electrically heated catalyst and at least one electric motor auxiliary drive.

[0002] Increasingly stringent legal regulations require that raw exhaust emissions from combustion engine vehicles be reduced as much as possible, particularly the harmful components of the exhaust gases produced by the combustion of the air / fuel mixture in the cylinders. To achieve this, the combustion engine is increasingly being combined with an electric motor to create a hybrid drive. In certain operating situations, the electric motor, powered by an on-board battery, contributes drive power, thereby reducing the power demand from the combustion engine and consequently lowering exhaust emissions. Furthermore, the electric motor can also be towed by the combustion engine or operated as a generator in regenerative braking mode to recharge the on-board battery.

[0003] Furthermore, it is state of the art to equip combustion engines with an exhaust aftertreatment system in which the environmentally harmful components of the exhaust gas are reduced or converted into harmless components. Various designs of catalytic converter units and filter devices are available for this purpose. Within the exhaust catalysts, a chemical conversion of combustion pollutants takes place through oxidation or reduction of the respective pollutant. For this purpose, the exhaust catalysts have active catalytic zones in which the chemical conversion occurs via a catalytic reaction.

[0004] These systems and components, along with the associated methods and processes, are well known to those skilled in the art. It is also known that the efficiency of the aforementioned catalysts is, in some cases, highly dependent on the operating temperature. The required operating temperature typically ranges from approximately 300 °C to approximately 600 °C, depending on the fuel and coating. A minimum temperature, the so-called start-up or light-off temperature, is usually required to initiate the conversion process. This can lead to unacceptably high, or at least undesirable, pollutant emissions, particularly during the period immediately following a cold start of the combustion engine. This negatively impacts the real-world total pollutant emissions of the combustion engine under real-world driving conditions, the so-called "Real Driving Emissions," which serve as a benchmark for pollutant emissions.Therefore, the aim should be to heat up the largest possible catalyst volume as quickly as possible, at least up to the light-off temperature.

[0005] It is therefore necessary to heat the exhaust catalyst to the desired operating temperature as quickly as possible. This can be achieved through combustion-related measures, meaning measures in which the combustion engine is operated in such a way that the waste heat in the exhaust gas itself can be used to quickly heat the exhaust catalyst. However, this generally leads to higher fuel consumption and can only shorten, but not eliminate, the period after a cold start of the combustion engine during which the catalyst is not yet functioning and increased levels of pollutants are emitted.

[0006] Alternatively or additionally, electrically heated exhaust catalysts (EHC = Electrically Heated Catalyst or E-CAT) are also known to be used. These exhaust catalysts have their own electric heating element, which is powered, for example, from the electrical system of a vehicle equipped with an internal combustion engine, i.e., from the vehicle's battery, and which can heat the exhaust catalyst to the desired operating temperature. One advantage of an electrically heated exhaust catalyst is that it can be brought up to operating temperature during a so-called catalyst cold phase, even without the engine running, i.e., before the engine is started. This means that pollutants are converted from the moment the engine is started.

[0007] In an electrically heated exhaust gas catalyst, the electrical heating device is implemented, for example, in the form of one or more electric heating discs through which the gas / exhaust gas flows, which convert electrical power into heating power and which are arranged in the immediate vicinity of a catalyst substrate that is itself unheated.

[0008] Since an electric heating disc has a comparatively small volume and the inner surface of the heating disc itself also has a catalytic coating, this catalytic surface is heated directly, i.e. on site and very quickly.

[0009] The design of such electrically heated exhaust gas catalysts is described, for example, in the publications DE 199 43 846 A1 and DE 44 34 673 A1.

[0010] To ensure functional reliability, i.e., the timely and sufficient heating of the catalyst in every operating situation, it is a prerequisite that the state of charge of the electrical energy storage device from which the catalyst heating is supplied, e.g., an on-board battery of a hybrid vehicle, is sufficient at all times, and especially when restarting the combustion engine from a partially or completely cooled state, to quickly heat the catalyst at least to the starting temperature.

[0011] The invention is therefore based on the objective of providing a battery management method and a battery management system for an on-board power supply battery of a hybrid motor vehicle, which ensures the operational reliability of an electrically heated catalyst of the exhaust aftertreatment device, particularly during or immediately before the start of the combustion engine, so that it can be operated particularly quickly and efficiently and exhibits improved conversion behavior, particularly in the start-up phase of the combustion engine.

[0012] This problem is solved according to the features of the independent method claim directed to a battery management method and the independent apparatus claim directed to a battery management system. Advantageous embodiments of the invention are the subject of the respective dependent claims.

[0013] The battery management method and the battery management system according to the invention result in a high level of operational reliability for the exhaust gas purification system, particularly during each restart of the combustion engine. Advantageously, it is ensured that the state of charge of the vehicle battery, which supplies the electric heating of the catalyst, is sufficient when the combustion engine is switched off to quickly heat the catalyst to at least the starting temperature upon restarting the combustion engine, even after it has completely cooled down and under the expected ambient conditions.

[0014] In this way, sufficient electrical energy is always provided to heat the electrically heated catalyst (EHC) before the start of the internal combustion engine to such an extent that a high conversion rate of pollutants is ensured right from the start of the internal combustion engine.

[0015] The battery management method according to the invention is used for an on-board battery of a hybrid motor vehicle with an internal combustion engine and at least one electric machine, wherein the internal combustion engine has an exhaust aftertreatment system with at least one electrically heated catalyst and at least one electric machine that can be operated in generator mode to charge the on-board battery. The battery's state of charge is continuously monitored and maintained at a required charge level by means of the electric machine, ensuring that the catalyst can be electrically heated from the on-board battery to an activation temperature during a subsequent cold start of the internal combustion engine.The required charge level of the vehicle battery is continuously determined during operation, depending on the aging state of both the catalyst and the vehicle battery, and the temperatures of the vehicle battery and catalyst expected during the following cold start.

[0016] The invention is based on the understanding that the power consumption of the electrically heated catalyst, as well as the performance characteristics of the vehicle battery, change over their service life and depend on other operating conditions, particularly temperature. This must be taken into account when determining the required charge level.

[0017] The term "on-board battery" generally refers to an electrical, rechargeable energy storage device, such as an accumulator, which is connected to an electrical on-board network or at least a part of an electrical on-board network of the hybrid vehicle and supplies energy via this on-board network to heat the electrically heated catalyst.

[0018] In one embodiment of the invention, the nominal charge capacity of the vehicle electrical system battery is used as a further determining factor for determining the required charge level of the vehicle electrical system battery. The nominal charge capacity is understood to be the maximum amount of energy that can be stored, as specified by the manufacturer, when the battery is fully charged and new. The age-related change in the maximum charge capacity is then taken into account in conjunction with the current state of aging.

[0019] As a further determining factor for determining the required charge level of the vehicle's electrical system battery, the electrical starting energy expected to be required for the subsequent cold start of the combustion engine can be considered or used. This ensures, for example, that if the catalytic converter heats up before the combustion engine is started, the vehicle's electrical system battery still has sufficient energy after the catalyst has heated up to start the combustion engine using the electric motor.

[0020] Naturally, the nominal charge capacity and the required electrical starting energy can also be used in combination to determine the required charge level of the on-board battery, thereby further increasing the functional reliability of the battery management procedure.

[0021] Another embodiment of the battery management system is characterized by the fact that, in addition to generator operation, the electric machine can also be operated in recuperation mode to recover kinetic energy from the hybrid vehicle, or in drive mode to start the combustion engine or to provide supplementary or sole propulsion for the hybrid vehicle. These operating modes are not mutually exclusive. While they cannot be used simultaneously, they can be used alternately, depending on the operating or driving conditions of the hybrid vehicle. For example, if the state of charge drops below the required level, the electric machine can be operated in generator mode, driven by the combustion engine, to recharge the vehicle's electrical system battery.Similarly, coasting or braking phases during hybrid vehicle operation can be used to feed electrical energy into the vehicle's battery through recuperation. Furthermore, the electric motor, similar to a starter-generator, can also be powered from the vehicle's battery to start the combustion engine during propulsion. In addition, the electric motor, powered by the vehicle's battery, can provide additional torque, for example, during acceleration phases of the hybrid vehicle, or be used as the sole, locally emission-free drive system in urban areas.

[0022] In a further development of the battery management method according to the invention, the aging state of the catalyst can be determined continuously or at intervals during operation. This can be done, for example, based on the operating hours of the combustion engine, for instance, using an hour meter. Alternatively or additionally, an average conversion rate during operation can also be determined and used to determine the aging state of the catalyst. Another possibility, which can be considered as an alternative or supplement to the aforementioned methods for determining the aging state of the catalyst, is to determine the average heating time of the catalyst during a cold start until it reaches the activation temperature and to derive the aging state from this. This enables a reliable determination of the aging state of the catalyst during operation and thus a reliable determination of the required charge level of the on-board battery.

[0023] Analogous to the determination of the catalyst's aging state, in a further embodiment of the inventive method, the aging state of the vehicle electrical system battery can be determined continuously or at intervals during operation. This is done, for example, by using measured values ​​for battery current and / or battery voltage during charging and / or discharging and the battery's temperature at the time the measured values ​​are acquired. However, an optional or supplementary numerical aging model of the vehicle electrical system battery can also be used, which is installed, for example, in an electronic control unit and enables a calculation of the battery's aging state during operation based on specific operating data. In this way, the aging state of the vehicle electrical system battery can be determined very reliably, and the required charge level can be determined with high accuracy on this basis.

[0024] Another advantageous embodiment of the method is characterized in that the temperature of the vehicle battery and catalyst expected during a cold start of the combustion engine, on which the required charge level of the vehicle battery is determined, is based on ambient temperature values ​​at the time the combustion engine was previously switched off. This assumes that, due to climatic conditions, generally no very large temperature fluctuations in the environment are to be expected over the average period between switching off and restarting the combustion engine. To increase the reliability of the method despite this simple estimation of the expected temperatures, a temperature reduced by a predetermined amount, for example by 5°C or 10°C, can be used to determine the required charge level of the vehicle battery.

[0025] Alternatively, the expected temperature of the vehicle's battery and catalytic converter during a cold start of the combustion engine can be estimated based on a temperature profile of the ambient temperature over a period prior to the engine being switched off. This allows for the determination of an average temperature level or, if necessary, a temperature range, for example, across day and night temperatures, which can then be used to make a more reliable estimate of the temperatures expected when the combustion engine is restarted. In this case as well, a safety correction to a lower value can be applied, as described above.

[0026] In both of the aforementioned cases, it is assumed that over an assumed period of time during which the system cools down with the combustion engine switched off, the temperatures of the catalyst and the on-board battery will equalize with the ambient temperature.

[0027] In another embodiment of the invention, the temperatures of the vehicle's electrical system battery and catalytic converter expected during a cold start of the combustion engine are estimated based on geographical data of the hybrid vehicle's location and geographically and seasonally associated expected temperature values ​​or temperature forecasts for the vehicle's ambient temperature. The hybrid vehicle's location can be determined, for example, via a GPS system assigned to the vehicle. The geographically and seasonally associated expected temperature values ​​or temperature forecasts can then be retrieved in real time from relevant databases, for example, via an internet connection. This allows even large-scale, temperature-relevant changes in the hybrid vehicle's location to be advantageously considered in the temperature estimation.

[0028] The stated problem is further solved by a battery management system according to the invention for an on-board battery of a hybrid motor vehicle with an internal combustion engine, which has an exhaust aftertreatment system with at least one electrically heated catalyst, and at least one electric machine that can be operated in generator mode to charge the on-board battery. The battery management system, which is represented, for example, by a separate electronic control unit or one integrated into a central vehicle control unit, is configured to carry out the battery management method according to one of the embodiments described above and is connected, in terms of control technology, at least to the on-board battery, the electric machine, and the electrically heated catalyst.For example, a sequence program is stored in a memory area of ​​the electronic control device, which is executed to control the method according to the invention.

[0029] The battery management system according to the invention advantageously ensures, in analogy to the method according to the invention, that the state of charge of the vehicle battery, which supplies the electric heating of the catalyst, is sufficient when the combustion engine is switched off to quickly heat the catalyst, even after complete cooling and under the expected ambient conditions, to at least the starting temperature when the combustion engine is restarted.

[0030] One embodiment of the battery management system according to the invention is characterized in that it has an electronic processor module which is set up to acquire measurement data and input information, to perform calculations required for the battery management method on the basis of the acquired measurement data and information, and to output resulting control signals, in particular according to a stored sequence program. This enables rapid, up-to-date acquisition of all relevant data and information and continuous control or regulation of the charge level of the vehicle's electrical system battery based on this data.

[0031] Another version of the battery management system features a power module designed to control power flows between the vehicle battery, the electric machine and the electrically heated catalyst, depending on the control signals from the aforementioned processor unit. This allows for a system-technical and spatial separation of the processor module, which naturally operates with comparatively low electrical currents and voltages, from the power module, which operates with comparatively high electrical voltages and currents, for example, to heat the catalytic converter and charge the vehicle's electrical system battery. This makes it easy to avoid mutual electrical and electromagnetic interference between the processor module and the power module.

[0032] Features of the illustrated embodiments can, provided they are not mutually exclusive or only alternatively applicable, individually or in combination supplement and further develop the subject matter of the independent claims. Advantages and embodiments of the invention

[0033] The battery management method or battery management system for an on-board battery of a hybrid vehicle is explained in more detail below using the following description of an exemplary embodiment with reference to the drawing. The drawing shows: Fig. 1 a simplified schematic representation of a hybrid motor vehicle with an embodiment of a battery management system according to the invention; Fig. 2 an example of a flowchart of a battery management method according to the invention; Fig. 3 a diagram illustrating the dependence of the power output of an on-board power supply battery on its state of aging; Fig. 4 a diagram illustrating the dependence of the power output of an on-board battery on its operating temperature and Fig. 5 a diagram illustrating the dependence of the power consumption of the heating of an electrically heated catalyst until the start-up temperature is reached, on its state of aging.

[0034] The Fig. Figure 1 shows a simplified schematic representation of a hybrid vehicle 10 with an internal combustion engine 20 and an electric machine 30 integrated into the drivetrain. An exhaust aftertreatment system 21 is connected to the internal combustion engine 20. This system comprises an exhaust pipe 24 connected to the internal combustion engine 20, an electrically heated catalyst 22 arranged in the exhaust pipe 24, and a further exhaust aftertreatment component 23, for example a particulate filter, located downstream of the catalyst 22 in the exhaust pipe 24. Furthermore, a battery management system 50 according to the invention, comprising a processor module 51 and a power module 52, an on-board battery 40, and a temperature sensor 56 are arranged in the hybrid vehicle 10.

[0035] The processor module 51 of the battery management system 50 is electrically connected to the electric motor 30, the electrically heated catalyst 22, the vehicle battery 40, the temperature sensor 56, and the power module 52 via signal connections 70. The power module 52 is electrically connected to the electric motor 30, the electrically heated catalyst 22, and the vehicle battery 40 via power connections 60. The signal connections 70 and power connections 60 shown here are also to be understood schematically and do not provide information about the actual number of connecting lines required between the individual components of the overall system for transmitting the necessary signal and power currents.

[0036] Signals from the vehicle battery 40 are transmitted via the signal connections 70 to the processor module 51. These signals are representative of the state of charge of the vehicle battery 40 and can be used to determine its aging state. Signals from the electrically heated catalyst 22 are transmitted to the processor module 51. These signals are representative of the current catalyst temperature and may also provide information about the catalyst's aging state. Signals from the temperature sensor 56 are transmitted to the processor module 51. These signals are representative of the ambient temperature.Signals can be transmitted between the electric machine 30 and the processor module 51, for example, providing information about the current operating conditions of the electric machine 30 or switching the electric machine 30 into different operating modes, such as generator operation, recuperation operation, or drive operation. Signals are transmitted between the processor module 51 and the power module 52 to control the power flows between the electric machine 30, the electrically heated catalyst 22, and the vehicle battery 40. For this purpose, the power module 52 is electrically connected to the electric machine 30, the electrically heated catalyst 22, and the vehicle battery 40 via power connections 60.

[0037] Such a configuration of the overall system makes it possible to continuously monitor the current charge level (SoC_curr) of the vehicle battery 40 and to maintain it at a required charge level (SoC_req) by means of the electric machine 30, so that electrical heating of the catalyst 22 to an activation temperature is reliably ensured by the vehicle battery 40 during a subsequent cold start of the combustion engine 20, whereby the required charge level (SoC_req) of the vehicle battery 40 is continuously determined during operation depending on the determined state of aging (SoH_Cat) of the catalyst 22, the determined state of aging (SoH_Bat) of the vehicle battery 40 and the ambient temperature (T_exp) of the vehicle battery 40 and catalyst 22 expected during the subsequent cold start.

[0038] In Fig. Figure 2 schematically illustrates the process of one embodiment of the method according to the invention in a block diagram. The block labeled Use_Bat generally represents an operating mode of the hybrid vehicle, referred to as Use_Bat, in which the vehicle battery 40 feeds energy into the vehicle's electrical system for various electrical functions. The following block, labeled SoC_curr, symbolizes the continuous monitoring of the current charge level, SoC_curr.

[0039] In parallel, the required charge level, SoC_req, is determined to ensure that the catalyst 22 is reliably heated to an activation temperature by the on-board battery 40 during a subsequent cold start of the combustion engine 20. This is symbolized by the block labeled SoC_req.The required charge level, SoC_req, is continuously determined during operation depending on the aging state, SoH_Cat, of the catalyst 22, the aging state, SoH_Bat, of the on-board battery 40, the ambient temperature, T_exp, of the on-board battery 40 and catalyst 22 expected during the following cold start, the nominal charge capacity, NCC_Bat, of the on-board battery and the electrical starting energy, StE_req, expected to be required for the following cold start of the internal combustion engine 20, which is symbolized by the correspondingly marked blocks that are directly connected to the SoC_req block, which symbolizes the determination of the required charge level SoC_req.

[0040] The block labeled SoC_curr < SoC_req symbolizes the continuous comparison of the current charge level SoC_curr of the on-board battery 40 with the determined required charge level SoC_req. If the current charge level SoC_curr is below the determined required charge level SoC_req, the system switches to a charging mode, Char_Bat, in which the on-board battery 40 is charged. This charging mode, Char_Bat, is maintained at least until the current charge level SoC_curr exceeds the required charge level SoC_req. Once this is achieved, the system switches back to the operating mode, Use_Bat.To avoid constantly switching back and forth between the use mode, Use_Bat, and the charging mode, Char_Bat, the value for the required charge level, SoC_req, can be increased by a safety margin in the charging mode, Char_Bat, which must be exceeded before switching to the use mode, Use_Bat.

[0041] Fig. Figure 3 shows a diagram illustrating the dependence of the power available from an on-board battery on its age and charge level. The available power, P, (vertical) is plotted against the charge level, SoC, (horizontal). The diagram includes a power curve for a new on-board battery, P_nBat, and a power curve for an on-board battery at the end of its specified service life, P_oBat, which lies consistently below the power curve P_nBat.

[0042] A dashed horizontal line represents the theoretical heating power required for the catalyst, HP_req, at 5 kW. The intersections of the required heating power, HP_req, with the power curves P_nBat and P_oBat show that the required charge level of the battery for heating the catalyst in a new state, SoC_req_nBat, is approximately 39%, whereas the required charge level of an aged battery, SoC_req_oBat, is significantly higher at approximately 53%. Therefore, as the vehicle battery ages, the required charge level, SoC_req, for heating the catalyst is higher than for a new vehicle battery. This must be taken into account when determining the required charge level, SoC_req.

[0043] Fig. Figure 4 shows a diagram illustrating the dependence of the power available from an on-board battery on the operating temperature. The available power, P, (vertical) is plotted against the state of charge (SoC), (horizontal). A power curve for an on-board battery at +10°C, P_+10°C, and a power curve for an on-board battery at -10°C, P_-10°C, are shown, the latter remaining consistently below the power curve P_+10°C. A dashed horizontal line represents the theoretical heating power required for heating the catalytic converter, HP_req, at 5 kW. The intersection points of the required heating power, HP_req, with the power curves P_+10°C and P_-10°C show that the charge level of the battery required to heat the catalyst in the "warm" state, SoC_req_+10°C, is approximately 30%, whereas the required charge level of the "cold" battery, SoC_req_-10°C, is significantly higher at approximately 54%.At low operating temperatures of the vehicle's electrical system battery, the required charge level (SoC_req) for heating the catalytic converter is higher than at higher operating temperatures. This must be taken into account when determining the required charge level (SoC_req).

[0044] Fig.Figure 5 shows a diagram illustrating the dependence of the required charge level, SoC_req, of the vehicle battery for heating the catalyst on the catalyst's state of aging. The available power, P, (vertical) is plotted against the charge level, SoC, (horizontal). The graph shows a power curve for a vehicle battery at -10°C, P_-10°C. It has been shown that a new catalyst requires less heating power, or less energy, to heat up to its activation temperature than an aged catalyst. In the example shown, the required heating power for a new catalyst, HP_req_nC, is approximately 5 kW and is shown with a dashed horizontal line. The required heating power for an aged catalyst, HP_req_oC, is approximately...A heating output of 6 kW was determined and also entered with a dashed horizontal line.

[0045] The intersection points of the two dashed horizontal lines HP_req_nC and HP_req_oC with the performance curve P-10°C show that the required charge level for the new catalyst, SoC_req_nC, is significantly lower at approximately 53% than the required charge level for the aged catalyst, SoC_req_oC, at approximately 66%. Therefore, the aging state of the catalyst must also be considered when determining the required charge level, SoC_req. Reference symbol list 10 Hybrid. Motor vehicle 20 internal combustion engine 21 Exhaust aftertreatment system 22 Catalyst 23 Exhaust aftertreatment component 24 Exhaust pipe 30 electric machine 40 On-board electrical system battery 50 Battery Management System 51 Processor module 52 Power module 56 Temperature sensor 60 power connection 70 Signal connection SoC (State of Charge) - Charge level of the vehicle's electrical system battery State of Health (SoH) SoH_Bat Aging status of the vehicle electrical system battery Use_Bat Operating mode of the vehicle electrical system battery Char_Bat charging operating mode of the vehicle electrical system battery NCC_Bat Nominal Charge Capacity SoC_curr: current charge level of the vehicle's electrical system battery SoC_req required charge level of the vehicle electrical system battery SoH_Cat Catalyst Aging State T_exp expected temperature StE_req required electrical starting energy P Performance P_nBat performance curve of a new on-board battery (new Battery) P_oBat performance curve of an aged vehicle electrical system battery (old Battery) P+10°C Performance curve of an on-board power supply battery at +10°C P-10°C Performance curve of an on-board electrical system battery at -10°C SoC_req_nBat required charge level for a new on-board battery SoC_req_oBat required charge level for an aged on-board battery SoC_req+10°C required charge level at +10°C heating power SoC_req-10°C required charge level at +10°C heating power SoC_req_nC required charge level for a new catalyst SoC_req_oC required charge level for an aged catalyst HP_req required heating power HP_req_nC required heating power of a new catalyst HP_req_oC required heating power of an aged catalyst QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 19943846 A1

[0009] DE 4434673 A1

[0009]

Claims

[1] Battery management method for an on-board network battery (40) of a hybrid motor vehicle (10) with an internal combustion engine (20) and at least one electric machine (30), - wherein the internal combustion engine (20) has an exhaust gas aftertreatment device (21) with at least one electrically heatable catalyst (22) and the at least one electric machine (30) can be operated in a generator mode for charging the on-board network battery (40); wherein the current charge level (SoC_curr) of the on-board power supply battery (40) is continuously monitored and maintained by the electric machine (30) at a required charge level (SoC_req), which reliably ensures electrical heating of the catalyst (22) to an activation temperature during a subsequent cold start of the internal combustion engine (20), fed from the on-board power supply battery (40), wherein the required charge level (SoC_req) of the vehicle electrical system battery (40) is continuously determined during operation as a function of - the ageing state (SoH_Cat) of the catalyst (22); - the ageing state (SoH_Bat) of the on-board network battery (40) and - the ambient temperature (T_exp) of the on-board network battery (40) and catalytic converter (22) to be expected during the following cold start. [2] Method according to claim 1, characterized by that the nominal charge capacity (NCC_Bat) of the on-board network battery (40) and / or the electrical starting energy (StE_req) expected to be required for the subsequent cold start of the internal combustion engine (20) are used as further determining factors to determine the required charge level (SoC_req) of the on-board network battery (40). [3] Method according to one of the preceding claims, characterized by that the electrical machine (30) in addition to the generator operation also - in a recuperation mode for recovering kinetic energy of the hybrid motor vehicle (10) or - is operable in a drive mode for starting the internal combustion engine (20) or for supporting or solely driving the hybrid motor vehicle (10). [4] Method according to one of the preceding claims, characterized by that the ageing state of the catalyst (22) is determined continuously or at intervals during operation on the basis of - operating hours of the combustion engine (20) and / or - an average conversion rate in operation and / or - an average heating time from cold start to activation temperature. [5] Method according to one of the preceding claims, characterized by that the ageing state of the vehicle electrical system battery (40) is determined continuously or at intervals during operation using - measured values for battery current and / or battery voltage during charging and / or discharging and a temperature of the vehicle electrical system battery (40) present when the measured values are recorded and / or - a numerical ageing model of the on-board network battery (40). [6] Method according to one of the preceding claims, characterized by that the temperatures of the on-board network battery (40) and catalyst (22) to be expected during a cold start of the combustion engine (20) - based on ambient temperature values at the time of the previous shutdown of the internal combustion engine (20) or - be estimated on the basis of a temperature value profile of the ambient temperature over a period of time before the preceding switching off of the internal combustion engine (20). [7] Method according to one of claims 1 to 5, characterized bythat the temperatures of the on-board network battery (40) and the catalyst (22) to be expected during a cold start of the internal combustion engine (20) are estimated on the basis of geographical data of the location of the hybrid motor vehicle (10) and of geographically and seasonally assigned temperature expectation values or of geographically assigned temperature forecasts for the ambient temperature of the hybrid motor vehicle (10). [8] Battery management system (50) for an on-board network battery (40) of a hybrid motor vehicle (10) with an internal combustion engine (20) and at least one electric machine (30), - wherein the internal combustion engine (20) has an exhaust gas aftertreatment device (21) with at least one electrically heatable catalyst (22) and - the at least one electrical machine (30) can be operated in a generator mode for charging the on-board network battery (40), wherein the battery management system (50) is set up to carry out the battery management method according to one of claims 1 to 7 and is connected in terms of control technology at least to the on-board network battery (40), the electrical machine (30) and the electrically heatable catalyst (22). [9] Battery management system (50) according to claim 8, characterized by , that it - an electronic processor module (51) which is designed to acquire measurement data, to carry out the arithmetic operations required for the battery management method on the basis of the acquired measurement data and to output control signals resulting therefrom. [10] Battery management system (50) according to claim 9, characterized by , that it - a power module (52) for controlling power currents between the on-board network battery (40), the electric machine (30) and the electrically heatable catalyst (22) as a function of the control signals of the processor module (51).

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