Method for operating a drive system for a motor vehicle, corresponding drive system for a motor vehicle, and computer program product

Abstract

The invention relates to a method for operating a drive system (1) for a motor vehicle, wherein the drive system (1) comprises a traction battery (2), an electric traction machine (5, 8) electrically connected to the traction battery (2), an internal combustion engine (11) and a generator (12) that can be driven by the internal combustion engine (11) and is electrically connected to the traction battery (2), wherein the drive system (1) comprises a first temperature control circuit (15) for temperature control of the traction battery (2) and a second temperature control circuit (16) for temperature control of the internal combustion engine (11).The invention further provides that the drive system (1) also has a third temperature control circuit for temperature control of the electric traction motor (5), and that the second temperature control circuit (16) is fluidically connected to the first temperature control circuit (15) via a first valve arrangement (18) and to the third temperature control circuit (17) via a second valve arrangement (17). The invention further relates to a drive system (1) for a motor vehicle and a computer program product.

Description

The invention relates to a method for operating a drive system for a motor vehicle, wherein the drive system comprises a traction battery, an electric traction motor electrically connected to the traction battery, an internal combustion engine, and a generator that can be driven by the internal combustion engine and is electrically connected to the traction battery, wherein the drive system comprises a first temperature control circuit for temperature control of the traction battery and a second temperature control circuit for temperature control of the internal combustion engine. The invention further relates to a drive system for a motor vehicle and a computer program product. For example, the prior art document CN 116101026 A describes a method for recovering engine waste heat from a vehicle, which comprises the following steps: determining whether there is a heating requirement for a passenger compartment and / or an energy cell of the vehicle at any given time; if there is a heating requirement for the passenger compartment and / or the energy cell, determining the current state of charge of the energy cell and determining a charging interval in which the current state of charge lies; and determining a waste heat recovery strategy for the vehicle based on the charging interval and / or the current road conditions in which the vehicle is located, and carrying out an engine waste heat recovery action based on the waste heat recovery strategy. Furthermore, document CN 220527026 U discloses a thermal management system comprising an outlet end of a range extender, a first inlet end of a heat exchanger, a battery pack, a second inlet end of a heat exchanger, an outlet end of a heat exchanger, a mechanical water pump and an inlet end of the range extender connected in series to form a first battery heating circuit, wherein the waste heat from the engine in the range extender is used to heat the coolant of the first battery heating circuit in order to heat and warm the battery pack. Further state of the art is known from the publications CN 115891561 A , DE 10 2019 103 520 A1 , EP 3 899 225 B1 , DE 10 2010 060 230 A1 , DE 10 2016 220 847 A1 and GB 2 552 199 A. The object of the invention is to propose a method for operating a drive system for a motor vehicle which has advantages over known methods, in particular enabling particularly efficient operation using the electric traction machine. According to the invention, this is achieved by a method for operating a drive system for a motor vehicle with the features of claim 1. It is provided that the drive system also has a third temperature control circuit for temperature control of the electric traction motor, and that the second temperature control circuit is fluidically connected to the first temperature control circuit via a first valve arrangement and to the third temperature control circuit via a second valve arrangement, wherein at least temporarily, temperature control fluid is exchanged between the first temperature control circuit and the second temperature control circuit for temperature control of the traction battery by means of the first valve arrangement, and at least temporarily, temperature control fluid is exchanged between the second temperature control circuit and the third temperature control circuit for temperature control of the electric traction motor by means of the second valve arrangement. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments described in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are possible. The drive system is preferably an integral part of the motor vehicle, but can of course also exist separately, particularly until the drive system is mounted on or in the motor vehicle. The drive system serves to propel the motor vehicle, thus providing drive torque for propelling the vehicle. To provide this drive torque, the drive system includes an electric traction motor. This motor is coupled to at least one wheel axle of the motor vehicle, so that it provides the drive torque at least temporarily at that wheel axle. The traction motor is electrically connected to the traction battery. The traction battery is an electrical energy storage device in which electrical energy is temporarily stored. For example, it is intended that the traction battery can be charged, at least temporarily, with externally supplied electrical energy. This means that the vehicle is electrically connected to an external charging station and the traction battery is charged using electrical energy supplied by the charging station. Since the amount of energy that can be temporarily stored in the traction battery is limited, the drive system incorporates a range extender. The range extender comprises the internal combustion engine and the generator. The generator is connected to the internal combustion engine, allowing it to be driven by the engine. At least temporarily, the generator is driven by the internal combustion engine and thus provides electrical energy through its generator operation. It is important to note that the internal combustion engine and the generator are preferably completely disconnected from the wheel axle, meaning they are not mechanically connected to it. The electrical energy supplied by the generator is, for example, fed at least temporarily and at least partially to the traction battery, which is electrically connected to the generator for this purpose. Additionally or alternatively, the supplied electrical energy is used, at least temporarily and at least partially, to operate the traction motor. It is therefore possible to supply the electrical energy supplied by the generator entirely to the traction battery, entirely to the traction motor, or partly to the traction battery and partly to the traction motor. The wheel axle, which can be driven by the traction motor, is, for example, one of several wheel axles of the motor vehicle, in particular a front axle or a rear axle. The traction motor is part of a drive unit that serves to drive the respective wheel axle. It can be provided that the drive unit is the first drive unit and that, in addition to the first drive unit, a second drive unit is part of the drive system. The second drive unit also has an electric traction motor. Preferably, the first drive unit is connected to a first wheel axle of the motor vehicle, and the second drive unit is connected to a second wheel axle. The first drive unit drives the first wheel axle, and the second drive unit drives the second wheel axle.Preferably, both the first traction machine and the second traction machine are electrically connected to the traction battery. The traction battery, traction motor, and internal combustion engine must be cooled, at least periodically. This means that heat is either removed from or added to them, particularly to adjust their respective temperatures towards their operating temperatures. The drive system has several temperature control circuits for this purpose. One circuit cools the traction battery, another cools the internal combustion engine, and a third cools the electric traction motor. Each circuit operates at least periodically to maintain the temperature of its respective component: the traction battery, the traction motor, or the internal combustion engine. For this purpose, a temperature control fluid is circulated in each temperature control circuit. The temperature control fluid is preferably in the form of a coolant. For example, it is provided that a fluid pump is located in each of the temperature control circuits, so that the temperature control fluid can be circulated separately and independently of the other temperature control circuits. Preferably, a heat exchanger is also provided in each of the temperature control circuits, which is specifically designed and configured to dissipate heat from the respective temperature control circuit or from the respective temperature control fluid towards the external environment of the vehicle. The heat exchanger can also be referred to as a radiator. The temperature control circuits are fluidically connected to each other via the first and second valve arrangements. Each valve arrangement has at least one switching valve. This means that each valve arrangement has exactly one switching valve or several switching valves. Fluidically, the first valve arrangement is located between the first and second temperature control circuits, and the second valve arrangement is located between the second and third temperature control circuits. Each valve assembly has at least two settings. In the first setting, the temperature control circuits connected to the respective valve assembly are fluidically separated from each other, and in the second setting, they are fluidically connected. This means that in the first setting, an exchange of temperature control fluid via the respective valve assembly between the temperature control circuits connected to it is prevented, whereas in the second setting, fluid exchange via the respective valve assembly between the temperature control circuits connected to it is permitted or occurs. In the first setting of the first valve arrangement, fluid exchange between the first and second temperature control circuits is prevented, whereas in the second setting of the first valve arrangement, temperature control fluid is exchanged between the first and second temperature control circuits. In the first setting of the second valve arrangement, fluid exchange between the second and third temperature control circuits is prevented, and in a second setting of the second valve arrangement, temperature control fluid is exchanged between the second and third temperature control circuits, at least temporarily. While it is generally known to use the heat generated during the operation of the internal combustion engine to temperature-control the traction battery in order to improve efficiency, the method described here achieves a further improvement in efficiency. For this purpose, the first and second valve arrangements are adjusted, at least temporarily, such that the temperature control fluid is exchanged between the temperature control circuits to temperature-control the electric traction machine, in particular to supply it with heat. The efficiency of the electric traction motor depends, at least in part, on its temperature. Optimal efficiency is achieved when the temperature corresponds to the traction motor's operating temperature. The further the temperature deviates from the operating temperature, either towards higher or lower temperatures, the lower the traction motor's efficiency. For this reason, heat should be supplied to the traction motor, at least intermittently, provided by the internal combustion engine and / or the traction battery. Additionally or alternatively, heat is dissipated from the traction motor and supplied to the internal combustion engine and / or the traction battery, at least intermittently.Additionally or alternatively, it is planned to supply heat provided by the internal combustion engine to the traction battery, or to supply heat provided by the traction battery to the internal combustion engine and / or the traction motor. For this purpose, the valve arrangements are adjusted accordingly and the temperature control circuits are operated accordingly. For heat exchange between the traction motor and the internal combustion engine, the second and third temperature control circuits are operated to circulate the temperature control fluid, and the second valve arrangement is adjusted such that the second and third temperature control circuits are fluidically connected. For heat exchange between the traction battery and the internal combustion engine, the first and second temperature control circuits are operated to circulate the temperature control fluid, and the first valve arrangement is adjusted such that the first and second temperature control circuits are fluidly connected. For heat exchange between the traction battery and the traction motor, the first, second, and third temperature control circuits are each operated to circulate the temperature control fluid. Additionally, the first valve arrangement is adjusted such that the first temperature control circuit is fluidically connected to the second, and the second valve arrangement is adjusted such that the second temperature control circuit is fluidly connected to the third. The fluid connection between the first and third temperature control circuits is thus established via the second temperature control circuit, preferably exclusively. This approach results in flexible operation and high efficiency of the drive system. A further development of the invention provides that the electric traction motor is heated, at least temporarily, by means of heat dissipated from the internal combustion engine and / or the traction battery, through appropriate adjustment of the first valve arrangement and / or the second valve arrangement. This has already been mentioned. Additionally, it is naturally intended that the temperature control circuits be operated in such a way that heat is exchanged between the internal combustion engine and / or traction battery on the one hand, and the traction motor on the other. This serves to achieve high efficiency. A further development of the invention provides that the traction battery is heated, at least temporarily, by means of heat dissipated from the internal combustion engine and / or the electric traction motor, through appropriate adjustment of the first valve arrangement and / or the second valve arrangement. In addition to or as an alternative to temperature control of the electric traction motor, temperature control, and in particular heating, of the traction battery can also be carried out. For this purpose, heat is supplied to the traction battery from the internal combustion engine or the traction motor. Here, too, it is provided that the valve arrangement is adjusted accordingly and the temperature control circuit is operated in such a way that heat is exchanged between the aforementioned devices. This achieves the advantages already explained. A further development of the invention provides that the internal combustion engine for driving the generator is operated depending on at least one of the following parameters: current charge level of the traction battery, traction engine temperature, traction battery temperature, ambient temperature, vehicle route, and user request. For example, it is possible to operate the internal combustion engine depending on only one of the aforementioned parameters. However, operation depending on several of the aforementioned parameters, or even all of them, is particularly preferred. The current state of charge (SoC) of the traction battery describes the amount of electrical energy currently stored in the battery. The state of charge is also commonly referred to as the SoC. The traction machine temperature refers to the temperature of the traction machine itself, such as the temperature of the machine housing, stator, or rotor. The traction machine temperature is measured or determined using a model. The traction battery temperature is the temperature of the traction battery. For example, the temperature inside the battery housing or inside a battery cell is used as the traction battery temperature. The traction battery temperature is also measured or determined using a model.The ambient temperature describes the temperature present in the external environment of the motor vehicle. The route of a motor vehicle is understood to be the route that the motor vehicle is expected to travel. The route is determined either predictively or upon request by the vehicle's user. The route typically starts from a point, such as the vehicle's current position, and extends to a destination. The destination is specified by the vehicle's user, for example, during route planning, or it is determined predictively, particularly based on data describing the vehicle's previous driving behavior. A user request describes a setting specified by the vehicle's user. For example, the user request is set via a control element and therefore depends on the control element's setting.The advantages described above are achieved by operating the internal combustion engine to drive the generator depending on at least one of the aforementioned quantities. A further development of the invention provides that, based on a start point and a destination point, the route of the motor vehicle and, based on the route, the charge level of the traction battery along the route are predictively determined. The route has already been discussed. It extends from the start point to the destination point. The current position of the motor vehicle is used, for example, as the start point. The destination point, on the other hand, is preferably specified by the user of the motor vehicle or determined based on statistical data describing the previous driving operation of the motor vehicle. Between the start point and the destination point, the route is determined by means of route planning, which preferably uses map data describing a road network in the vicinity of the motor vehicle. Based on the route, the charge level at each of several points along the route is predictively determined.For example, this is done based on topographical data that describe an elevation profile along the route. Based on the predictively determined charge level, it is determined whether the internal combustion engine is operated to drive the generator and thus provide electrical energy. This is the case, for example, if it is determined that the charge level will fall below a certain threshold along the route. Specifically, in this case, the internal combustion engine is operated even before the current charge level falls below the threshold or a different threshold. This allows for particularly targeted use of the range extender. A further development of the invention provides that if the charge level falls below a threshold value due to the current charge level and / or the predictively determined charge level of the traction battery, the internal combustion engine is operated to drive the generator, and the electrical energy supplied by the generator is used to operate the traction motor and / or the traction battery is supplied with energy. The operation of the internal combustion engine is thus adjusted depending on the current charge level and / or the predictively determined charge level. For example, the internal combustion engine operates if either the current charge level or the predictively determined charge level falls below the charge level threshold. If this condition is met, the range extender is operated to provide electrical energy, which is either used directly to power the traction motor or first supplied to the traction battery. In either case, a sufficiently long vehicle range and high efficiency are achieved. A further development of the invention provides that if the charge level threshold is exceeded by the current charge level and / or the predictively determined charge level of the traction battery, the internal combustion engine is operated, provided that a temperature, in particular the traction engine temperature, the traction battery temperature, and / or the ambient temperature, falls below a temperature threshold. Thus, if the temperature is lower than the temperature threshold, the range extender should be operated, provided that the current charge level or the predictively determined charge level is simultaneously higher than the charge level threshold. This ensures that at low temperatures, sufficient heat is provided by the internal combustion engine to warm the traction engine and / or the traction battery, thereby achieving particularly efficient operation. The advantages already described are again achieved. A further development of the invention provides that the internal combustion engine operates independently of the temperature as long as the charge level falls below a further charge level threshold. This further charge level threshold is lower than the charge level threshold; in particular, it corresponds to a minimum permissible charge level of the traction battery. This means that the range extender is always operated if the traction battery, due to its low charge level, can no longer provide electrical energy to operate the traction engine. This ensures reliable operation of the vehicle. The invention further relates to a drive system for a motor vehicle, in particular for carrying out the method according to the explanations in this description, wherein the drive system comprises a traction battery, an electric traction machine electrically connected to the traction battery, an internal combustion engine and a generator which can be driven by the internal combustion engine and is electrically connected to the traction battery, wherein the drive system comprises a first temperature control circuit for temperature control of the traction battery and a second temperature control circuit for temperature control of the internal combustion engine. The drive system is designed to also include a third temperature control circuit for temperature control of the electric traction machine, and the second temperature control circuit is fluidically connected to the first temperature control circuit via a first valve arrangement and to the third temperature control circuit via a second valve arrangement, wherein the drive system is designed and configured to exchange temperature control fluid at least temporarily between the first temperature control circuit and the second temperature control circuit for temperature control of the traction battery by means of the first valve arrangement and at least temporarily between the second temperature control circuit and the third temperature control circuit for temperature control of the electric traction machine by means of the second valve arrangement. The advantages of such a drive system design and procedure have already been discussed. Both the drive system and the method for operating it may be further developed as explained in this description, and reference is made to those explanations. Furthermore, the invention relates to a computer program product comprising commands that cause the drive system to execute the described method as described herein. For the advantages and possible advantageous embodiments, reference is made to the description in its entirety. The features and combinations of features described in the description, in particular those described in the following figure description and / or shown in the figures, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention, in particular the scope of the claims. Thus, embodiments that are not explicitly shown or explained in the description and / or the figures, but which emerge from or can be derived from the explained embodiments, particularly within the scope of the claims, are also to be considered as encompassed by the invention. The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. Figure 1, the only one, shows a schematic representation of a drive system for a motor vehicle in a first embodiment. Figure 1 shows a schematic representation of a drive system 1 for a motor vehicle in a first embodiment. The drive system 1 includes a traction battery 2, which is designed and configured for the intermediate storage of electrical energy. Furthermore, the drive system 1 has a first drive unit 3 and a second drive unit 4. The first drive unit 3 comprises a traction motor 5, an inverter 6, and a gearbox 7. The traction motor 5 is electrically connected to the traction battery 2 via the inverter 6. It is connected to a wheel axle of a motor vehicle, for example, a front axle, via the gearbox 7. The second drive unit 4, analogous to the first drive unit 3, comprises a traction motor 8, an inverter 9, and a gearbox 10. The traction motor 8 is electrically connected to the traction battery 2 via the inverter 9 and is driven by the gearbox 10 and connected to a second wheel axle of the vehicle. Furthermore, the drive system 1 comprises an internal combustion engine 11 and a generator 12, which together form a range extender 13. The generator 12 is connected to the internal combustion engine 11 for drive purposes and is electrically connected to the traction battery 2 via an inverter 14. The drive system 1 has a first temperature control circuit 15 for temperature control of the traction battery 2. A second temperature control circuit 16 serves to temperature control the internal combustion engine 11, and a third temperature control circuit 17 serves to temperature control the first drive unit 3, the second drive unit 4, and the inverter 14.In an alternative embodiment, it may also be provided that the first temperature control circuit 15 serves to temperature control the traction battery 2, the second temperature control circuit 16 serves to temperature control the internal combustion engine 11, the generator 12 and the inverter 14, and the third temperature control circuit 17 serves to temperature control the first drive unit 3 and the second drive unit 4. In each case, a first valve arrangement 18 and a second valve arrangement 19 are present. The first valve arrangement 18 is fluidically located between the first temperature control circuit 15 and the second temperature control circuit 16, and the second valve arrangement 19 is fluidically located between the second temperature control circuit 16 and the third temperature control circuit 17. The first valve arrangement 18 allows the first temperature control circuit 15 and the second temperature control circuit 16 to be fluidically connected, and the second valve arrangement 19 allows the second temperature control circuit 16 and the third temperature control circuit 17 to be fluidically connected. At least temporarily, the valve arrangements 18 and 19 are set such that heat supplied by the traction battery 2 and / or the internal combustion engine 11 is fed to the third temperature control circuit 17 and thus to the traction motor 5 and / or the traction motor 8. This occurs depending on at least one of the following parameters: the current charge level of the traction battery, the temperature of the traction motor, the temperature of the traction battery, the ambient temperature, the vehicle's route, and the user's request. This ensures a particularly high efficiency of the drive system 1. REFERENCE MARK LIST: 1 Drive system 2 Traction battery 3 1st drive unit 4 2nd drive unit 5 Traction motor 6 Inverter 7 Gearbox 8 Traction motor 9 Inverter 10 Gearbox 11 Internal combustion engine 12 Generator 13 Range extender 14 Inverter 15 1st temperature control circuit 16 2nd temperature control circuit 17 3rd temperature control circuit 18 1st valve assembly 19 2nd valve assembly

Claims

Method for operating a drive system (1) for a motor vehicle, wherein the drive system (1) comprises a traction battery (2), an electric traction machine (5, 8) electrically connected to the traction battery (2), an internal combustion engine (11), and a generator (12) that can be driven by the internal combustion engine (11) and is electrically connected to the traction battery (2), wherein the drive system (1) comprises a first temperature control circuit (15) for temperature control of the traction battery (2) and a second temperature control circuit (16) for temperature control of the internal combustion engine (11), characterized in that the drive system (1) also comprises a third temperature control circuit (17) for temperature control of the electric traction machine (5), and the second temperature control circuit (16) is fluidically connected to the first temperature control circuit (15) via a first valve arrangement (18) and to the third temperature control circuit (17) via a second valve arrangement (19).wherein at least temporarily, temperature control fluid is exchanged between the first temperature control circuit (15) and the second temperature control circuit (16) for temperature control of the traction battery (2) by means of the first valve arrangement (18) and at least temporarily, temperature control fluid is exchanged between the second temperature control circuit (16) and the third temperature control circuit (17) for temperature control of the electric traction machine (5, 8) by means of the second valve arrangement (19). Method according to claim 1, characterized in that the electric traction machine (5, 8) is heated at least temporarily by means of heat removed from the internal combustion engine (11) and / or from the traction battery (2) by appropriately adjusting the first valve arrangement (18) and / or the second valve arrangement (19). Method according to one of the preceding claims, characterized in that the traction battery (2) is heated at least temporarily by means of heat removed from the internal combustion engine (11) and / or from the electric traction machine (5, 8) by appropriately adjusting the first valve arrangement (18) and / or the second valve arrangement (19). Method according to one of the preceding claims, characterized in that the internal combustion engine (11) is operated to drive the generator (12) depending on at least one of the following quantities: current charge level of the traction battery (2), traction engine temperature, traction battery temperature, ambient temperature, route of the motor vehicle and user request. Method according to one of the preceding claims, characterized in that the route of the motor vehicle and, based on the route, a charge level of the traction battery (2) along the route are predictively determined using a starting point and a destination point. Method according to one of the preceding claims, characterized in that when a charge level threshold is undershot by the current charge level and / or the predictively determined charge level of the traction battery (2), the internal combustion engine (11) is operated to drive the generator (12) and electrical energy provided by means of the generator (12) is used to operate the traction machine (5, 8) and / or supplied to the traction battery (2). Method according to one of the preceding claims, characterized in that if the charge level threshold is exceeded by the current charge level and / or the predictively determined charge level of the traction battery (2), the internal combustion engine (11) is operated, provided that a temperature falls below a temperature threshold. Method according to one of the preceding claims, characterized in that the internal combustion engine (11) is operated independently of the temperature, provided that the charge level falls below a further charge level threshold value. Drive system (1) for a motor vehicle for carrying out the method according to one or more of the preceding claims, wherein the drive system (1) comprises a traction battery (2), an electric traction motor (5, 8) electrically connected to the traction battery (2), an internal combustion engine (11), and a generator that can be driven by the internal combustion engine (11) and is electrically connected to the traction battery (2), wherein the drive system (1) comprises a first temperature control circuit (15) for temperature control of the traction battery (2) and a second temperature control circuit (16) for temperature control of the internal combustion engine (11), characterized in that the drive system (1) also comprises a third temperature control circuit (17) for temperature control of the electric traction motor (5, 8).8) and the second temperature control circuit (16) is fluidically connected to the first temperature control circuit (15) via a first valve arrangement (18) and to the third temperature control circuit (17) via a second valve arrangement (19), wherein the drive system (1) is designed and configured to exchange temperature control fluid at least temporarily between the first temperature control circuit (15) and the second temperature control circuit (16) for temperature control of the traction battery (2) by means of the first valve arrangement (18) and at least temporarily between the second temperature control circuit (16) and the third temperature control circuit (17) for temperature control of the electric traction machine (5, 8) by means of the second valve arrangement (19). Computer program product comprising commands that cause the drive system (1) according to claim 9 to execute the method according to one or more of claims 1 to 8.

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