Method for overload protection of at least one electrical component in an electrical circuit of a motor vehicle and control device for a motor vehicle, motor vehicle and storage medium

Abstract

Method for overload protection of at least one electrical component (16) in an electrical circuit (11) of a motor vehicle (10), wherein at least one overload case (31) is defined for the respective electrical component (16), according to which an overload exists if a current intensity (19) of an electrical current (I) flowing through the component (16) is above a respective threshold value (33) for longer than a respective predetermined time period (32), and a processor circuit (22) operates a respective mean value filter (30) for protection against the respective overload case (31), which repeatedly calculates a respective current mean value (M) of the current intensity (19) according to a predetermined calculation rule over a respective current time interval (34) corresponding to the respective time period (32) predetermined by the overload case (31) and outputs a time signal (36) of the mean value (M) at a filter output (35),and a predetermined protective measure (23) for the component (16) is controlled in dependence on the time signal (36), characterized in that , a) in the circuit (11), a power prediction circuit (24) of an energy storage device (12') of the circuit (11) carries out a prediction routine (25) for predicting an electrical power that can be delivered and / or absorbed by the energy storage device (12') in a predetermined future time interval, and depending on the prediction, a signal (26) for controlling an operating behavior of at least one other component (27) of the circuit (11) is generated, and the protective measure (23) acts on the signal (26) of the power prediction circuit (24), and / or b) one mean value filter (30) is provided for each component (16) for several overload cases (31) and the several mean value filters (30) are operated in parallel, and / or c) at least one separate overload case (31) is defined for several components (16) of the circuit (11).

Description

[0001] The technology disclosed here relates to a method for overload protection for at least one electrical component in an electrical circuit of a motor vehicle. An overload is defined as an electrical current in the electrical component having a current intensity greater than a predefined threshold value for longer than a predetermined period of time. Different overload cases can occur for each component, differing in the length of time for which threshold value must be exceeded for an overload to occur. The invention also encompasses a control unit by means of which overload protection can be provided in a circuit of a motor vehicle, a computer-readable storage medium for implementing the overload protection in a control unit, and a motor vehicle having a control unit according to the invention.

[0002] A motor vehicle contains electrical circuits or switching circuits, each of which may include an electrical power supply, the on-board electrical system (wiring), and at least one electrical component connected to the on-board electrical system. Such a circuit may contain one or more power electronic components that are subject to high requirements in terms of current-carrying capacity. For example, a power converter for operating an electrical machine in a motor vehicle's drive system must be able to handle a current of more than 50 or even more than 100 amperes. However, if an electrical current flows continuously above a certain threshold, this can lead to the aforementioned overload, which can result in overheating, for example. For example, an excessively high electrical current under known operating conditions can exceed the thermal load capacity of a power electronic component.But not only power electronic components, but electrical components in general can be at risk from such an overload.

[0003] However, it is not possible to measure the current temperature of every component, so overheating cannot be detected by measurement everywhere. For example, in connectors, relays, or other components that do not have dedicated temperature sensors to protect the component, excessive current can cause damage to the component or even its failure, without this being detectable in advance by measuring a temperature increase. This can then also render a vehicle unfit for operation.

[0004] Effective temperature protection generally requires dedicated temperature sensors in the respective component, which is not always feasible due to space constraints, for example, in a connector. The costs of providing such temperature monitoring can also be undesirably high.

[0005] An alternative to temperature measurement can be to estimate the current temperature of a component using a digital model. This involves measuring the electrical current flowing through the component in question and using a thermal model to determine how hot the component might currently be. If it is detected that the maximum permissible temperature has been exceeded, a protective measure is initiated, such as shutting down the circuit.

[0006] However, this control system interrupts the operation of the vehicle's circuit due to overheating. It would be advantageous, however, if overheating could be prevented in advance.

[0007] However, an electrical component in a circuit is not only at risk from overheating. Another overload scenario can arise when excessive current causes wear or aging of a component, such as a relay or a connector. In these cases, wear can occur at the contact points of mechanically separable contacts due to high currents, for example, due to corrosion or oxidation. A voltage drop due to excessive current can also lead to aging or even breakdown of electrical insulation. Temperature measurement and / or a digital thermal model do not provide protection against these overload scenarios.

[0008] DE 10 2016 209 354 A1 discloses an overcurrent protection device for a high-voltage vehicle electrical system, comprising a semiconductor switch configured to disconnect a supply line of the system and a current measuring device configured to detect a value of an indicator for the strength of a load current flowing through the semiconductor switch. A disadvantage of this device is that no power prediction circuit is provided, the signal of which controls the operating behavior of a component of the circuit, and the signal can be modified by the protection device.

[0009] DE 197 27 825 A1 describes a monitoring method for an electrical circuit into which a time-varying current is fed from a power grid. Here, too, a disadvantage is that no power prediction circuit is provided, the signal of which controls the operating behavior of a component of the circuit, although the signal can be modified by the protective device.

[0010] The invention in DE 10 2007 006 564 A1 relates to a miniature circuit breaker or power switch in which an actuator element, which interrupts the current path between the input terminal and the output terminal, is electronically controlled. Here, too, it is disadvantageous that no power prediction circuit is provided, the signal of which controls the operating behavior of a component of the circuit, whereby the signal can be modified by the protective device.

[0011] DE 10 2009 027 387 A1 discloses a device and a method for reliably protecting an electrical line with a controllable switching element that can assume at least two states: a first state with a first resistance and a second state with a second resistance lower than the first resistance. A disadvantage here, too, is that no power prediction circuit is provided, the signal of which controls the operating behavior of a component of the circuit, whereby the signal can be modified by the protective device.

[0012] DE 10 2014 200 946 A1 discloses an overload monitoring device for an electrical system, wherein parameters are generated from measured values, and an overload situation is detected based on the measured values ​​and / or the parameters using time data from a time measuring device. A disadvantage here, too, is that no power prediction circuit is provided, the signal of which controls the operating behavior of a component of the circuit, although the signal can be modified by the protective device.

[0013] A preferred object of the technology disclosed here is to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution. In particular, a preferred object of the technology disclosed here is to protect at least one electrical component in a circuit of a motor vehicle from at least one overload event. Further preferred objects may arise from the advantageous effects of the technology disclosed here.

[0014] The objects are achieved by the subject matter of the independent patent claims. The dependent patent claims represent preferred embodiments. Further advantageous embodiments of the invention are described in the following description and the figures.

[0015] The invention provides a method for providing overload protection for at least one electrical component in an electrical circuit of a motor vehicle. At least one overload case is defined for the respective electrical component, according to which an overload or overload exists if the current intensity of an electrical current flowing through the component is above a respective threshold value for longer than a predetermined period of time. An overload case therefore has the two parameters "duration" and "threshold value" in relation to the current intensity. The type of overload, for example due to overheating or contact corrosion or voltage damage, does not have to be defined. One overload case or several overload cases can be defined for a respective component.Two different overload scenarios can arise, for example, if an overload can be generated in the component by a peak current and a continuous current. The peak current lasts for a shorter period than the continuous current, but a higher threshold applies than for the continuous current. For example, a component can be overloaded if a current greater than 200 amperes flows for at least 10 seconds. A component can also or alternatively be overloaded if a current greater than 40 amperes flows for at least 10 minutes.

[0016] A processor circuit is provided to carry out the method. This processor circuit operates a mean value filter to protect against each respective overload case. One mean value filter is therefore provided for each monitored overload case and for each electrical component to be protected. The mean value filter monitors "slidingly" by generating a time signal made up of a series or sequence of mean values ​​that are calculated continuously or step by step one after the other. The current signal value of the time signal is obtained by calculating the mean value by calculating a current mean value of the current over a current time interval according to a predetermined calculation rule. The time interval over which the mean value is calculated corresponds to the time period specified by the overload case.As will be explained later, the terms “duration” and “time interval” must be distinguished, since in the case of a recursive mean calculation the time interval of the mean filter can only be equivalent to the duration.

[0017] The resulting time signal of the mean value is output at a filter output of the mean value filter. The respective current signal value of the time signal indicates the current mean value, which is calculated over the immediately preceding time interval, for example, over the last 10 seconds. Therefore, the current values ​​within the immediately preceding time interval are taken into account to calculate the mean value according to the calculation rule. The time interval for the respective mean value filter is selected so that it corresponds to the specified time period specified by the respective monitored overload case.

[0018] The processor circuit controls a predetermined protective measure for the component depending on the time signal of the mean value. The time signal of the mean value can be converted or mapped, for example, using a mapping rule or mapping function, into a control signal for the protective measure, such as an upper limit for the current intensity of the current in question. For example, a characteristic curve, a look-up table, or a calculation formula can be used for this purpose. A person skilled in the art can determine a suitable functional relationship based on measurement tests.

[0019] The invention offers the advantage that no complex monitoring of the actual temperature of an electrical component in a circuit is necessary. Instead, by defining a specific overload event (duration and threshold value for the current), each overload event can be monitored before it occurs using the time signal of the mean value. The protective measure can also consist of preventing the specific overload event, so that an emergency shutdown of the circuit is not necessary. Instead, by adapting the operating mode of the motor vehicle, continuous operation of the same can be enabled without an actual overload event occurring. The mean value filter can thus, for example, simulate or estimate the process of heating up the component. The protective measure can then throttle the current before overheating occurs.The applicable current threshold values ​​can be found in the component specification.

[0020] According to one aspect of the invention, the protective measure acts on a so-called power prediction circuit. For this purpose, this power prediction circuit is provided in an energy storage device of the circuit, and the power prediction circuit executes a prediction routine to predict the electrical power that can be delivered and / or absorbed by the energy storage device for a predetermined future time interval. Such a prediction routine for an energy storage device is known in the prior art. For example, a corresponding power prediction circuit is part of a traction battery or battery for a drive system of a motor vehicle. The prediction routine states which power flow (delivered and / or absorbed electrical power) is expected for a predetermined future time interval (for example, the next ten seconds or the next 30 seconds).Depending on the prediction routine, the power prediction circuit generates a signal for controlling the operating behavior of at least one other component of the circuit (i.e., an electrical component other than the circuit's energy storage device). This signal can, for example, specify the target value for the power and / or current in the circuit. The protective measure acts accordingly on this signal of the power prediction circuit. Thus, if the power prediction circuit generates a signal for controlling the operating behavior of at least one component of the circuit, for example, to specify the electrical power and / or current to be converted by this component, the protective measure can now manipulate or falsify this signal in order to bring about the described throttling.Thus, at least one component of the circuit implements a reduced electrical power and / or current, so that not only the result of the prediction routine is taken into account, but also the at least one overload case.

[0021] According to a further aspect of the invention, it is additionally or alternatively provided that a mean value filter is provided for each component for multiple overload cases, and the multiple mean value filters are operated in parallel. Thus, a protective measure can be controlled for each component for different overload cases, since a respective differential signal is available. Thus, a component can be protected against multiple possible overload cases without having to provide a separate sensor system for each possible overload case.

[0022] According to a further aspect of the invention, it is additionally or alternatively provided that at least one separate overload case is defined for each component of the circuit. For example, the circuit can be digitally simulated, and a mean value filter or a parallel connection of several mean value filters can be used or provided for each component to be monitored. Thus, a difference signal is available for all monitored components of the circuit at any time for each overload case, which can be used to determine the remaining difference to the respective threshold value defined by the overload case.

[0023] The invention also includes embodiments which provide additional advantages.

[0024] In one embodiment, the processor circuit determines a difference signal for each mean filter, which determines the difference between the respective time signal of the mean filter and the respective threshold value of the overload case. The difference signal indicates a difference of the time signal from the respective threshold value, and the control of the protective measure is carried out depending on the determined difference signal. The general dependence on the respective time signal of the mean value, as stated above, thus results indirectly via the difference signal. Each overload case therefore includes a moving mean filter and a difference signal determined from its time signal, which determines the distance or difference of the time signal from the threshold value.The differential signal indicates how far the component is from the respective overload event, i.e., the difference or distance between the mean current value and the threshold value. The differential signal can be used to control the protective measure, especially when the overload event has not yet occurred, but the mean current is still below the threshold value. It is then possible to detect an approach to the threshold value and thus an approach to the overload event, and to control the protective measure in such a way that the overload event is counteracted preventively. Since there is a separate differential signal for each overload event, a respective protective measure or a central protective measure can be controlled individually for all overload cases to be monitored.

[0025] In one embodiment, the protective measure controlled by the difference signal comprises, in the event that the difference signal signals that the mean value is below the threshold value, a throttling control for throttling an electrical power and / or current in the circuit counteracts a further approach of the mean value to the threshold value. In other words, a further increase of the mean value towards the threshold value is slowed down or prevented. For this purpose, an electrical power that is converted in the circuit and / or a current that flows through the component is reduced or throttled. The throttling takes place in relation to, for example, a setpoint value that can actually be predetermined for the operation of the circuit, for example by a control unit of the motor vehicle.This setpoint is changed or influenced by the throttling control, so that the originally externally specified setpoint is reduced or throttled in such a way that a reduction in power and / or current results, which counteracts the further approach of the mean current to the threshold. In this case, it can be provided that the mean can approach the threshold further, but at a slower rate. This embodiment offers the advantage of counteracting the overload before it occurs. The throttling control can be implemented, for example, as a circuit for a control unit and / or as a control program for a processor of a control unit.

[0026] In one embodiment, the amount of a reduction in power and / or current caused by the throttling control is set as a function of an amount of the difference, as signaled by the difference signal, and / or as a function of a gradient of the difference signal. The smaller the amount of the difference, the greater the reduction. The steeper or greater the gradient of the difference signal, the greater the reduction. The intervention in the operation of the circuit is therefore greater or stronger the closer the mean value is to the threshold value and / or the steeper or faster the mean value approaches the threshold value when the mean value is smaller than the threshold value. The throttling of power and / or current is thus advantageously carried out in a demand-oriented manner.If the threshold is exceeded, the throttle can be set to increase the further the threshold is exceeded. In this case, the circuit can also be shut down.

[0027] In one embodiment, the throttling effected by the throttling control is applied to a battery in the circuit and / or to an electrical machine in the circuit. With regard to the battery, for example, its power output and / or power consumption can be reduced. If, for example, a certain power output and / or power consumption is specified by the said setpoint, this can be reduced as a function of the difference signal as a protective measure. With regard to an electrical machine, the mechanical power generated by it and / or the electrical power generated in generator mode can also be reduced. By throttling the current released by the battery, the circuit as a whole is effectively and advantageously protected. By throttling the electrical machine, a main source of overload is advantageously throttled.

[0028] In one embodiment, the respective averaging filter comprises a non-recursive filter. A non-recursive filter stores the measured current values ​​individually for the specified time interval of the averaging calculation and then calculates the average using the calculation rule. This requires a correspondingly large data memory to store all current values. The advantage of a non-recursive filter is that the time interval of the averaging filter corresponds exactly to the time period to be monitored, as defined by the overload case.

[0029] In one embodiment, the respective mean value filter comprises a recursive filter. A recursive mean value filter requires less storage space than a non-recursive filter. The time base or the time interval for which the mean value is calculated depends on the so-called feedback component of the recursive filter. The larger the feedback component, the larger the monitored time interval or the time interval considered for the mean value. By selecting an appropriate feedback component, a recursive filter can be adjusted to the time period to be monitored, as specified by the overload case. A recursive filter has the advantage that it can be implemented with low data storage requirements.

[0030] In one embodiment, a PT1 filter is provided as the recursive filter. This has proven particularly advantageous in terms of memory requirements and computational effort for implementing the method.

[0031] In one embodiment, the said calculation rule on the basis of which the mean value is calculated comprises calculating an RMS value (RMS - Root Mean Square) or an MS value (MS - Mean Square) as the mean value. The individual current values ​​are therefore squared, then summed, and the sum is then scaled to an average value (divided by the number of measured values ​​or as a moving average), which yields the MS value and is optionally mapped to the RMS value using a square root. This calculation rule has proven particularly advantageous for controlling the protective measure, since squaring results in increased or particular sensitivity for large deviations of the current value from the mean value. For example, a current measurement signal can be fed to a squarer, which generates squared signal values.The resulting signal of the squared signal values ​​can be converted into the mean signal using the mean filter. A recursive low-pass filter, for example, can be used as the mean filter. This can be implemented as a TP1 filter.

[0032] To carry out the method according to the invention, the described processor circuit must be operated. For this purpose, the invention provides a non-volatile, computer-readable storage medium on which program instructions are stored which, when executed by the processor circuit, cause it to carry out an embodiment of the method according to the invention. Such a storage medium can be designed, for example, as a flash memory or as an SSD (Solid State Disc) or as an HDD (Hard Disk Drive), or generally as a non-volatile digital data storage device. The program instructions can be designed, for example, as so-called binary code (machine language) for the processor circuit.

[0033] To carry out the method in a motor vehicle, the invention provides a control unit that is configured to receive a respective current intensity signal relating to a respective current intensity of a circuit from at least one measuring circuit. For this purpose, the control unit can be coupled to the at least one measuring circuit, for example, via an electrical line and / or a data bus. The control unit further comprises said processor circuit, which is coupled to an embodiment of the storage medium according to the invention and is configured to carry out an embodiment of the method according to the invention. For this purpose, the processor circuit can have at least one CPU (Central Processing Unit) and / or at least one GPU (Graphical Processing Unit).

[0034] Finally, the invention also encompasses a motor vehicle with a circuit in which at least one electrical component is provided. The circuit can, for example, be based on an on-board electrical system of the motor vehicle. The circuit can, for example, have an electrical generator and / or an accumulator (battery) as an electrical energy source. The circuit can, for example, have a transistor or a relay or a connector or a power converter or an electrical machine or a cable or a circuit board as a component, to name just a few examples. The overload case defined for a component can, for example, be taken from or read off a data sheet for the respective component. An overload case can also be determined through measurements or tests on a prototype of the respective component.In the motor vehicle according to the invention, the circuit is coupled to at least one measuring circuit for a current signal relating to a current in the circuit. Such a measuring circuit can be based on prior art technology, for example, on measuring the current using a shunt resistor and / or a Hall sensor. In the motor vehicle according to the invention, an embodiment of the control unit according to the invention is provided, which can receive or accept the current signal from the respective measuring circuit.

[0035] In the context of the invention, the term “motor vehicle” refers in particular to a passenger car, truck or motorcycle.

[0036] The technology disclosed here will now be explained using the figures. They show: Fig. 1 is a schematic representation of an embodiment of the motor vehicle according to the invention; Fig. 2 a diagram with a schematic curve of a measurement signal of a current; Fig. 3 a diagram with a schematic curve of the current intensity and a schematic curve of a time signal of an average value of the current intensity; Fig. 4 a diagram with a schematic curve of a time signal of an average value and illustration of the calculation of a difference signal; and Fig. 5 a diagram with a schematic curve of a temperature signal that was measured by means of an additional temperature sensor during a test of the invention.

[0037] In the following description of the alternative embodiments illustrated in the figures, the same reference numerals are used for features that are identical and / or at least comparable in their design and / or mode of operation compared to other embodiments illustrated in the figures. Unless explained again in detail, their design and / or mode of operation corresponds to the design and / or mode of operation of the features already described above.

[0038] Fig. 1 shows a motor vehicle 10 in which a circuit 11 may be provided, which may include, for example, a hybrid traction battery (e.g., a so-called 48-V mild hybrid system) or, more generally, a battery 12, an electrical system 13, power electronics 14 (e.g., a power converter), and an electric machine 15. The circuit 11 shown is merely an example of a circuit. A circuit may generally include an electrical energy source and / or an electrical storage device, as well as at least one electrical component that is operated together with the electrical energy source and / or the electrical energy storage device. Fig. Figure 1 illustrates how an electrical current I can be generated in the circuit 11 by the battery 12 based on a cell stack C, which can be switched by means of an electrical component 16, for example, an electrical switch or relay. The current I can be fed via the vehicle electrical system 13 to the power electronics 14, which can adjust phase currents for different electrical phases 17 of the electric machine 15 based on the current I so that the electric machine 15 acts, for example, as the drive of the motor vehicle 10.

[0039] A measuring circuit 18 can be coupled to the circuit 11, which can measure the respective current intensity 19 of the current I. By measuring the current intensity 19 continuously or at predetermined times, the measuring circuit 18 can provide a measurement signal or current intensity signal 20 of the current I, which can be provided to a control unit 21. The control unit 21 can contain a processor circuit 22, which, based on the current intensity signal 20 of the measuring circuit 18, can control one or more protective measures 23, by means of which an overload or an overload for the component 16 and / or at least one further or different component (not shown) can be prevented.

[0040] The battery 12 can, for example, operate a power prediction circuit 24, which determines, in a manner known per se, what electrical power the battery 12 can convert (absorb and / or deliver) in a predetermined future time interval. Based on a power prediction generated by a prediction routine 25, the power prediction circuit can generate a signal 26, which can be used, for example, as a component 27 of the power electronics 14 to control the electrical power converted by the electric machine 15 such that it operates according to the predicted power capability or the electrical power that can be provided or absorbed by the battery 12. The protective measure 23 can act on the signal 26 of the power prediction circuit 24 to effect an additional throttling 28 of the power.This results in a corresponding reduction in the current intensity 19 of the current I, so that a load on the component 16 by the current I can be reduced.

[0041] To control the protective measure 23, the processor circuit 22 can operate one or more mean value filters 30 for the current signal 20 to calculate a moving average of the current 19. It is shown how two mean value filters 30 can be operated in parallel. However, the number can also be fewer than two or more than two. One or more mean value filters 30 can be operated for the component 16 alone or for several components. By means of the respective mean value filter 30, a possible overload case 31 relating to the monitored component 16 is monitored. An overload case 31 is defined by a time period 32 and a threshold value 33, both of which relate to the current 19 of the current I flowing through the respective component 16.The respective mean value filter 30 calculates a current mean value for a time interval 34 which corresponds to the time duration 32, so that a time signal 36 of the mean value M is produced as a moving mean value filter 30 at a filter output 35. By forming or calculating the difference between the time signal 36 and the threshold value 33, a difference signal 38 is produced which indicates how far below or above the threshold value 33 the current mean value M is. As a result, the throttling 28, for example, can be adjusted continuously or step by step as a protective measure 32 depending on the currently signaled difference between the mean value M and the threshold value 33, so that the protective measure 31 can be controlled depending on the difference signal 38.

[0042] Fig. Figure 2 illustrates, over time t in seconds s, how the current intensity 19 of the current I can change or vary. The positive and negative current values ​​indicate that, for example, the electric machine 15 can be operated both in motor mode and in generator mode. The power prediction circuit 24 can define a power limit using signal 26. If the throttling 28 is then applied to the signal 26 as a protective measure 32, the adjusted signal 26' results, which also includes the protection of the component 16 against an overload 31. Fig. 2 shows that, for example, at a time TD, the throttling 28 is applied to prevent the occurrence of an overload event 31. In other words, the operation of the circuit 11 is still possible because the overload event 31 is successfully prevented by the throttling 28.

[0043] Fig. 3 shows, by way of example, how the current mean value M can be calculated in an average value filter 30 over time t, starting from a current time T1 for a past time interval 34, which corresponds to the time interval 32 defined by the respective monitored overload case 31. Since the current mean value M is updated over time t, the overall time signal 36 results at the filter output 35. To illustrate the effect of the average value filter 30, the time curve of the current intensity 19 of the current I, i.e. the current intensity signal 20, is also illustrated.

[0044] The mean value filter thus considers the current values ​​of current 19 from the current time T1 back to a time T0, which is defined by the end of the monitored time interval 34. The monitored time interval 34 can, for example, be precisely specified by a non-recursive filter or be an equivalent time interval that results from a recursive filter in a known manner depending on the feedback component. A preferred recursive filter is the TP1 filter.

[0045] Fig. Figure 4 illustrates how, in the difference calculation D, a difference 40 of the time signal 36 of the mean value M to the threshold value 33 can be calculated. The illustrated difference 40 applies to the current time T1. Thus, the total difference signal 38 results over time t.

[0046] Fig. 5 illustrates that in the event that the difference signal 38 signals that the time signal 36 has not yet exceeded the threshold value 33, but the difference 40 is smaller than a predetermined value, the throttling 28 can be triggered. Fig. Figure 5 illustrates a measurement result from a test drive in which, in addition to the processor circuit 22 with the mean value filters 30, a temperature sensor was also operated in the battery 12. However, this temperature sensor is not necessary for the implementation of the method, but was only used for its verification. It shows how a temperature signal 41, which can represent the temperature of the component 16, increases over time t. If the throttling 28 is then activated at time TD (see Fig.2), this can counteract a further increase in temperature, so that, for example, a critical temperature 42, which represents a thermal overload of component 16, can be prevented. Thus, uninterrupted operation of circuit 11 is possible, while still avoiding overloading each monitored component 16 by controlling protective measure 32 by means of the respective differential signal 38, even if an overload event 31 has not yet occurred.

[0047] In the processor circuit 22, corresponding program instructions can be stored in a storage medium S.

[0048] The battery 12 represents an energy storage device 12' of the circuit 11.

[0049] The protective measure 23 can be implemented or realized, for example, by a throttling circuit 23', which can be provided or realized, for example, by a control unit of the motor vehicle.

[0050] In other words, the technology disclosed here takes into account the following aspects: 1. A current-based calculation of the component-specific heat input during operation of the components. 2. Comparison of the heat input with the current carrying capacity according to the manufacturer's specifications. 3. Reduction of the specific heat input in the component through intelligent predictive control of the power supplying sources and / or current drawing loads in the on-board power system. 4. Replacement of the physically exact, but complex online calculation algorithms regarding the locally impressed heat input by simple averaging methods such as digital signal filters and thus a computing power-saving implementation of the temperature protection algorithms in the vehicle.

[0051] The implementation can be provided as follows: In order to avoid overheating of the battery disconnect switch and / or another component in a circuit, the time-averaged root mean square value of the battery current is determined continuously or at predetermined times (RMS current) and the power of the centrally power-generating electric machine is reduced via the vehicle operating strategy even before a permissible RMS time limit (threshold value) is reached. - This reduces the battery's charge / discharge current (and thus RMS value) and prevents any further temperature increase in the battery and the battery disconnect switch. - In the vehicle, the required current averaging and the corresponding comparison with the maximum permissible times for certain current limits are approximated by a simple (PT1) low-pass filtering of the squared current.

[0052] The advantages are the following: 1) Cost-effective temperature component protection through intelligent evaluation of current values ​​in the vehicle. 2) High safety and availability of vehicle functions. Avoiding breakdowns.

[0053] Fast reaction capability in the field via alternative parameterization of the current protection algorithms in the event of unforeseeable aging phenomena - e.g. increased resistance due to contact oxidation and thus increased critical heat input in components.

[0054] Simply integrating the current over time is completely inadequate for a non-linear temperature development of a component (theoretically, the heat conduction, radiation, and convection currents would have to be continuously calculated). Instead, a method is provided that is based on component current measurements and compares several RMS currents continuously determined during vehicle operation with different experimentally determined limit values / permissible component currents for short / long periods of time. If it becomes apparent during driving that one or more RMS thresholds are exceeded, the current is successively reduced until the affected RMS value (time signal of the mean value) decreases again (to a value less than the threshold or less than the threshold minus a predetermined buffer value), and then the full system power can be operated again (according to the specified setpoint, i.e., without throttling).This makes complete deactivation of the circuit unnecessary, ensuring maximum functional availability. The method is closely aligned with real-world conditions (measured nonlinear thermal properties of the components). In a second approach, a very fast and / or computationally efficient implementation of the precise RMS degradation algorithm (i.e., the aforementioned calculation rule) in the vehicle is achieved using a parameterization of a PT1 curve based on an RMS calculation.

[0055] In the context of the technology disclosed herein, the term "essentially" (e.g., "essentially vertical axis") includes the exact property or value (e.g., "vertical axis") as well as deviations that are insignificant for the function of the property / value (e.g., "tolerable deviation from vertical axis").

[0056] The foregoing description of the present invention is for illustrative purposes only and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention and its equivalents.

Claims

[1] Method for overload protection of at least one electrical component (16) in an electrical circuit (11) of a motor vehicle (10), wherein at least one overload case (31) is defined for the respective electrical component (16), according to which an overload exists if a current intensity (19) of an electrical current (I) flowing through the component (16) is above a respective threshold value (33) for longer than a respective predetermined time period (32), and a processor circuit (22) for protection against the respective overload case (31) operates a respective mean value filter (30), which repeatedly calculates a respective current mean value (M) of the current intensity (19) according to a predetermined calculation rule over a respective current time interval (34) corresponding to the respective time period (32) predetermined by the overload case (31), and outputs a time signal (36) of the mean value (M) at a filter output (35),and a predetermined protective measure (23) for the component (16) is controlled in dependence on the time signal (36), , characterized by , that a) in the circuit (11), a power prediction circuit (24) of an energy storage device (12') of the circuit (11) carries out a prediction routine (25) for predicting an electrical power that can be delivered and / or absorbed by the energy storage device (12') in a predetermined future time interval, and depending on the prediction, a signal (26) for controlling an operating behavior of at least one other component (27) of the circuit (11) is generated, and the protective measure (23) acts on the signal (26) of the power prediction circuit (24), and / or b) one mean value filter (30) is provided for each component (16) for several overload cases (31) and the several mean value filters (30) are operated in parallel, and / or c) at least one separate overload case (31) is defined for several components (16) of the circuit (11). [2] Method according to claim 1, wherein a difference signal (38) is determined which indicates a difference (40) of the time signal (36) from the respective threshold value (33), and the control of the protective measure (23) is carried out in dependence on the determined difference signal (38). [3] Method according to claim 2, wherein the protective measure (23) comprises that, in the event that the difference signal (38) signals that the mean value (M) is below the threshold value (33), a throttling control (23') for throttling (28) an electrical power and / or the current intensity (19) in the circuit (11) counteracts a further approach of the mean value (M) to the threshold value (33). [4] Method according to claim 3, wherein an amount of a reduction in the power and / or current (19) caused by the throttling control (23') is set as a function of an amount of the difference (40) and / or as a function of a gradient of the difference signal (38). [5] Method according to claim 3 or 4, wherein the throttling (28) is applied to a battery (12) of the circuit (11) and / or to an electric machine (15) of the circuit (11). [6] Method according to one of the preceding claims, wherein the respective mean filter (30) comprises a non-recursive filter. [7] Method according to one of the preceding claims, wherein the respective mean filter (30) comprises a recursive filter. [8] Method according to claim 7, wherein the recursive filter is designed as a PT1 filter. [9] Method according to one of the preceding claims, wherein the calculation rule comprises calculating an RMS value, root mean square value, or an MS value, mean square value, as the mean value (M). [10] Non-volatile, computer-readable storage medium (S) on which program instructions are stored which, when executed by a processor circuit (22), cause the latter to carry out a method according to one of claims 1 to 9. [11] Control unit (21) for a motor vehicle (10), wherein the control unit (21) is configured to receive from at least one measuring circuit (18) a respective current intensity signal (20) relating to a current intensity (19) of a current (I) of a circuit (11) of the motor vehicle (10), characterized by , that the control unit (21) has a processor circuit (22) which is connected to a storage medium according to claim 10 and is adapted to carry out a method according to one of claims 1 to 9. [12] Motor vehicle (10) with a circuit (11), wherein the circuit (11) is coupled to at least one measuring circuit (18) for a current intensity signal (20) relating to a current (I) of the circuit (11), characterized by that a control device (21) according to claim 11 is provided in the motor vehicle (10).

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