EP3769095A1

EP3769095A1 - Method for monitoring a supply system of a motor vehicle

Info

Publication number: EP3769095A1
Application number: EP19714335.7A
Authority: EP
Inventors: Michael Frommberger; Sebastian GOSS; Bastian Hitz; Monika LENG
Original assignee: Leoni Kabel GmbH
Current assignee: Leoni Kabel GmbH
Priority date: 2018-03-19
Filing date: 2019-03-19
Publication date: 2021-01-27
Also published as: DE102018204182A1; WO2019180002A1; CN111971567A; US20210063457A1

Abstract

The invention relates to a method for monitoring a supply system (2) of a motor vehicle, in particular a high-voltage supply system of an electrically driven motor vehicle, comprising at least two electric components (4, 6) which are connected together via a cable (8). The cable (8) is part of the supply system (2) which additionally has a number of sensors (20, 26) for monitoring at least one state variable of the supply system (2). State variable values which are ascertained by the sensors (20, 26) are used to infer the functionality of the supply system (2).

Description

description

The invention relates to a method for monitoring an electrical supply system of a motor vehicle, in particular a high-voltage supply system of an electrically driven motor vehicle, having at least two components connected to one another via a cable, wherein the cable part of the supply system.

In the automotive sector, cables are subject to generally high mechanical or thermal stresses, for example, which can affect the functionality and performance characteristics of the cable as well as its service life. The mechanical loads include mechanical stresses caused especially by vibrations, for example scouring of insulating material or also influencing electrical contact connections. Thermal loads can arise, for example, in the region of hot (engine) components or else as a result of high currents.

Cables for a motor vehicle are usually designed in such a way that they can reliably withstand the expected loads for the intended service life. Typically, cables are therefore often oversized compared to the actual requirements.

Particularly in the area of high-voltage components, for example in a high-voltage drive train of an electrically driven vehicle, the load is high not least even at high electrical power. Both an overdimension ning as well as an unforeseen failure of the cable should be avoided.

Proceeding from this, the object of the invention is to specify a method for monitoring a supply system of a motor vehicle, in particular a high-voltage supply system, in order to ensure reliable operation of the motor vehicle.

The object is achieved according to the invention by a method for monitoring a supply system of a motor vehicle, especially a high-voltage supply system with the features of claim 1. Preferred Weitererbil applications are included in the dependent claims. The supply system has at least two electrical components connected by a cable, the cable being part of the supply system. The supply system further has a number of sensors which are designed to monitor at least one state variable of the supply system. The values of these state variables ascertained by the at least one sensor are evaluated in a suitable manner, and the functional capability of the supply system is deduced based on these determined values.

Supply system of a motor vehicle in the present case is understood to mean, in particular, a system (permanently) installed inside the vehicle which has the at least two components and the cable. Specifically, these are high-voltage and high-performance components, which are provided for an electric drive train for the ferry operation of the vehicle. These high-performance components are, in particular, a power electronics component, an electric motor, in particular a drive motor for driving the vehicle and / or a battery. This configuration is specifically characterized by continued monitoring during operation by the detection the sensor data allows continuous monitoring or monitoring at discrete intervals of the supply system. The recorded sensor data are thereby wise provided with a timestamp and stored. Historical data is then compared with currently acquired data and, for example, also compared with changes or a gradient of the changes and monitored. Based on this information, a statement about the current state and the current functionality of the supply system is determined and, in particular, a prognosis for the (residual) service life of the supply system.

By means of this control and monitoring, the current state is known almost at any time, and measures can be taken in good time in the event of a decline in functionality.

The functionality of the supply system is understood to mean, in particular, that a statement is made about the entire system or about subcomponents thereof. It is concluded by the recorded sensor data on the functionality and quality especially of the electrical supply of the components. In addition, however, a statement about the state of the components based on the sensor data is preferably made. Thus, for example, an increased, e.g. consumption of a connected component (motor) caused by a defect can be detected by a temperature measurement on the cable.

The state variables are, for example

- the temperature of the cable, the connected components or the environment,

- - Mechanical parameters, such as information on mechanical loads, such as bending, especially vibration, or

- electrical state variables that provide information about the electrical load (voltage, current, frequency).

According to a preferred embodiment, the sensor itself is integrated in the cable. In this case, the cable is an intelligent cable which itself acquires status data about the state variables. Of particular importance tion is that conclusions about the status of the entire system are made about the condition data of the cable. As stated above, a temperature in the cable is used, for example, based on the then a statement about the state of a component, such as a motor, or even about the state of a connector between the component and the cable is made.

To form the sensor integrated in the cable, the cable preferably has a line element into which a sensor signal is fed and an answer signal is evaluated. The sensor signal is fed in by means of a suitable supply unit and the response signal is evaluated by an evaluation unit. The feed unit and evaluation unit are typically arranged on the same side of the cable. The feed unit is integrated, for example, in a plug of the cable or in a connected thereto supply unit. The evaluation unit itself can be integrated in the feed-in unit or it can also be arranged remotely therefrom. In the latter case, the response signal, also referred to as a reflected signal, is transmitted to the evaluation unit.

The line element is a wire extending along the cable or a pair of wires or another electrical line element.

For evaluating the response signal / reflected signal component, a propagation time measurement is preferably provided, for example in the form of a time domain reflectometry, TDR for short (Time Domain Reflectometry). In this case, a measuring pulse is fed into the sensor wires and the voltage profile of the reflected signal component or response signal is evaluated.

As an alternative to a TDR measurement, a measuring method is preferably used, as described in the subsequently published WO 2018/086949 A1. Their disclosure content, in particular their claims (with accompanying explanations) are hereby expressly included in the present application. Specifically, reference is made to claims 1, 2, 6, 7 and 12 with the associated versions specifically on pages 5/6 and 8/9. In this case, several individual measurements are carried out in the course of a measurement cycle, wherein a measurement signal (measurement pulse) is fed from the feed unit into the sensor wires per single measurement, wherein when exceeding a predetermined voltage threshold (at the feed) due to the reflected signal component, a stop signal is generated, wherein a transit time between the input of the measurement signal and the stop signal is determined, and wherein the voltage threshold value between the individual measurements is changed. The feeding of the measuring pulse takes place, for example, according to a measuring or sampling frequency.

Therefore, exactly one stop signal is generated for each individual measurement. A further evaluation of the reflected signal does not take place. Due to the threshold value changed between the individual measurements, different impurities, which thus lead to different amplitudes in the reflection, are detected by the different propagation times, in particular also locally resolved.

Due to the large number of individual measurements, the transit times (stop signals) of the reflected components are therefore generally recorded at different threshold values. In this respect, this method can be regarded as a voltage-discrete time measuring method. The number of individual measurements is preferably more than 10, more preferably more than 20 or even more than 50 and, for example, up to 100 or even more individual measurements. From the large number of these individual measurements, a large number of stop signals are thus determined, which are arranged distributed over time. The plurality of stop signals in conjunction with the threshold values therefore approximately represent the actual signal course of the injected measurement signal and the reflected components. Conveniently, from these stop signals, the actual signal profile for a fed-in and reflected at the power end measurement signal is approximated, for example by a mathematical Kurvenfit. A respective individual measurement is preferably terminated on the basis of the measurement principle according to the invention, as soon as a stop signal has been issued. In order to reliably check the line as to whether there are a plurality of identical impurities, each resulting in a reflected portion with comparable signal amplitude, a measured dead time is predetermined in a preferred embodiment after a first individual measurement during which the measuring arrangement is quasi deactivated and not on a stop signal responds. Specifically, it is provided that, after a first individual measurement and a detected first stop signal, a second individual measurement is made in which preferably the same threshold value is set as in the first individual measurement. The measurement dead time, within which no detection of a stop signal takes place, is (slightly) greater than the travel time between the start signal and the stop signal detected during the first individual measurement. This avoids that the reflected portion associated with the first stop signal is detected in the second individual measurement. This cycle is preferably repeated several times until no further stop signal is detected. That is to say, the test dead time is respectively adapted to the transit time of the (first, second, third, etc.) stop signal detected in the previous individual measurement, that is, selected to be slightly larger, until no further stop signal is emitted to this set threshold value.

Conveniently, a signal curve is measured by suitably setting the respective test dead time in combination with a variation of the threshold value. In particular, this also detects falling edges in the signal curve. Signal peaks with rising and falling edges can therefore be detected and evaluated.

Both in the method described in WO 2018/086949 A1 and in a TDR method, the measuring principle is based on the fact that the propagation of the measuring signal within the line element depends on the state variables to be measured. For temperature measurement, for example, a temperature-dependent dielectric is used for the line element, so that the propagation speed changes as a function of the temperature. Mechanical loads or even local thermal loads lead to a local change in the dielectric / line impedance, so that at the sen points a (partial) reflection of the measurement signal occurs, which is used for the evaluation. In this case, a localization of such an impurity is possible.

In a preferred embodiment, an external sensor is arranged outside the cable and is also provided for detecting a state variable.

Conveniently, the external sensor is arranged in addition to the internal sensor of the cable. In this respect, a double detection of sensor data is provided. Under external sensor is understood here that this is not integrated in the cable. At the same time, however, the external sensor is preferably positioned at or in the immediate vicinity of the supply system. In particular, it is arranged inside the vehicle.

The external sensor is preferably a vibration sensor for detecting vibrations, especially vibrations of components of the supply system. Especially in the automotive sector, the unavoidable vibrations that occur during operation are a decisive mechanical load, which can lead to the impairment of electrical systems and also their functionality.

The vibration sensor is arranged for this purpose at a suitable location. In particular, the vibration sensor is arranged in a connection region between the cable and at least one of the two connected components. The connection is in particular a plug connection. As a result of this measure, the vibrations are detected and evaluated directly, especially in the critical connection area, in order to be able to derive statements about the current functionality of the system.

In general, an external sensor is preferably arranged in addition to the sensor integrated in the cable. There are therefore sensor data of both the cable internal Sensor as well as the external sensor considered and evaluated to close on the current functioning of the supply system.

An external vibration sensor is preferably combined with a built-in cable sensor, such as temperature or bending sensor. Preferably, different state variables are detected by the external sensor and the internal sensor. Alternatively, the same state variables are used with the two sensors, as shown in FIG. Temperature, recorded. In a particularly expedient embodiment, a measured value obtained from the integrated sensor is checked and verified on the basis of the measured value of the external sensor. It is therefore checked whether the data transmitted by the cable-internal sensor are plausible. By means of this comparison with an external sensor, for example false diagoses are reduced by the cable-internal sensor. Specifically, for example, a bending sensor integrated in the cable sensor and its data are compared with the movement data of the external sensor and verified whether the data is plausible.

For the evaluation of the obtained data and measured values, these are preferably compared with a comparison system and based on this comparison a statement about the functionality is made. Within the comparison system empirical values are stored, for example in tabular form, so that current state information is derived by comparison with the comparison system.

Alternatively, the comparison system is a mathematical model, which thus simulates the real system and describes it mathematically as a function of the variable state variables. The comparison system is expediently integrated in an evaluation unit to which the measurement data are transmitted. This evaluation unit is integrated, for example, in a control unit of the vehicle. Alternatively, however, it can also be used in a higher-level control center or even in a non-Z manufacturer of the Vehicle belonging organizational unit can be arranged. For example, the data contained by the sensors are transmitted to the manufacturer (supplier) of the cable or of the supply system, which in this way monitors the functioning of the supply system, in particular continuously during operation, in the sense of a service.

In an expedient embodiment, the state variables are detected in a plurality of supply systems, especially in different vehicles built supply systems of the same type and transmitted to this superior, common and thus central evaluation point and evaluation.

The collected data are preferably used for a modification of the comparison system. This allows continuous optimization and further development of the comparison system in order to improve the accuracy of the information.

In addition to the internal sensor and the external sensor, preferably at least one further, external data source, such as e.g. a vehicle control, used and taken into account. From this, for example, conclusions about the current state of the supply system can also be derived from the control commands and / or the measured data from the sensors are subjected to a plausibility check.

According to a further independent aspect, a method for monitoring a charging system of an electrically driven vehicle is provided, wherein the charging system comprises a charging station, a charging cable, a battery as well as a number of sensors, based on the values determined by the sensors for the state variable is deduced on the functionality of the charging system. At least one of the variables temperature, mechanical load (eg bending, vibration) and moisture are preferably monitored as state variables. Preferably, the charging cable is monitored for these variables. It is expedient to monitor several and in particular all of these three variables.

The advantages and preferred embodiments mentioned above with regard to the supply system in the motor vehicle are to be transferred to the charging system in the same way. The cable versions must therefore be transferred to the charging box.

In general, the method described here is not necessarily limited to use in the automotive sector. As an alternative, it is also applied to electrical supply systems, for example in (industrial) plants, in which electrical components, in particular consumers, are supplied with energy via a cable.

An embodiment of the invention will be explained in more detail with reference to the figure. This shows in a schematic, highly simplified representation of an electrical supply system of a motor vehicle, especially a high-voltage supply system.

The FIGURE shows a supply system 2 which has a first component 4, a second component 6 and a cable 8 connecting these two components 4, 6. The first component is in particular a vehicle battery 4, in the case of the second component 6 in particular power electronics, such as an inverter and especially an electric motor 6, which is designed as a drive or drive motor for driving the electrically operable motor vehicle is. The traction motor 6 is connected to a control unit 10 in connection. The two components 4, 6 can furthermore have integrated monitoring units 12 which, for example, detect state variables of these in the components 4, 6, such as, for example, temperature, current current consumption or current output. The cable 8 is over connections 14A, 14B on the one hand connected to the battery 2 and on the other hand to the electric motor 6. This may be, for example, connectors. Alternatively, the individual supply lines of the cable 8 are firmly contacted, for example by terminals, screw terminals, etc.

The cable 8 is generally a supply cable, which typically has a plurality of electrical supply wires, which is designed for power transmission of the required power between the battery 4 and the electric motor 6. In this high-voltage system, power of several 10 kW, typically more than 50 kW and typically more than 100 kW continue to be transmitted during operation. Electric drive powers are often in the range between 100 and 200 kW. For larger vehicles or higher power ratings, electrical power of up to 500 kW or up to almost 1,000 kW is also transmitted. The voltage for such systems is typically in the range of a few hundred volts.

In the exemplary embodiment, a line element 16, hereinafter also referred to as a sensor line, is integrated into the cable 8. Insofar, the line element 16 is part of an integrated sensor 20 of the cable 8. Alternatively, a discretely arranged sensor could also be arranged in the cable path 8 or at several points of the cable 8 ,

The sensor based on the line element 16 or the method for determining a value of a state variable, such as, for example, the temperature of the cable, is based on the fact that a measurement signal is fed into the line element 16 and a response signal is determined thereon. The response signal is typically a reflected signal. This embodiment is based on the consideration that reflections within the cable (line element 16) occur and are rejected due to defects within the cable. The measuring signal is fed by means of a feed unit 22. The reflected signal runs back to the feed unit 22 and is for example selected there directly or transmitted to an evaluation unit 24. telt. The feed unit 24 is integrated, for example, in a connector 14A.

In addition, a further, external sensor 26 is provided, which is designed as a vibration sensor. This is arranged at critical, vibration-loaded points, preferably in the connection region 14B to the second component 6 out. There occur operationally particular high-frequency vibrations, since the electric motor 6 is connected to a drive axle and thus vibrations are transmitted through contact with the road. The connection point to the battery 4, however, is less loaded.

Furthermore, a further vibration sensor can be arranged at a reference point, which serves as a reference base and as a comparison basis. The evaluation unit 24 is designed to receive the sensor data, preferably both of the integrated sensor 20 and of the external sensor 26. The data of these sensors 20, 26 are detected as sensor data S. In addition, further measurement data or information about the state variables are preferably acquired, which originate, for example, from further external sensors arranged outside the supply system or also from the monitoring units 12 or also from the control unit 10. The relevant information is referred to as external data E transmitted to the evaluation unit 24. On the basis of the transmitted current data, the evaluation unit 24 determines the current functional status. Depending on the current Funktionszu- state then the operation is controlled or regulated in a preferred embodiment, especially if a functional impairment has been determined, this is used for a current limit.

Furthermore, it is provided that on the basis of the transmitted sensor data, a prediction about the expected remaining life is taken. For this purpose, for example, in the evaluation unit 24, a comparison system deposited, especially a mathematical model, which maps the supply system 2 and based of which the influence of the values of the individual state variables on the real supply system 2 can be simulated and evaluated for predictions.

According to an alternative application, the supply system 2 is designed as a charging system, in which case one of the two components 4, 6 represents a charging station and the other represents the motor vehicle battery 4. The cable 8 is formed in this case as a charging cable.

The remarks on the supply system are analogously also transferred to the charging system.

Due to the need to reduce the charging time, high-performance charging systems are being used. It is specifically developed for charging power of 500A and more at 1000V, but this is not the limit, especially with regard to the snow removal of trucks. With charging capacities beyond 500kW, the issue of safety takes on a new status. Especially in cooled charging systems, the charging line is the warmest element in the charging system on the temperature side. By integrating continuously measuring sensors 20, 26, as described above, the mean line temperature of the charging cable and / or a localization of a hotspot are detected, for example. By means of two differently arranged sensor elements 20, 26, a distinction is preferably made between heating from the inside (by high charging current) or heating from outside (for example, solar irradiation). The internal temperature of the charging cable is preferably determined by the integrated sensor 20 and the externally acting temperature, preferably by the external sensor 26.

According to a preferred embodiment, the sensor, in particular the integrated sensor 20, is designed for the detection of a fluid intrusion into the interior of the charging cable 8, which is due to a crack in the outer jacket (eg penetration of rainwater) or a crack of the inner cooling hoses (outlet of cooling liquid) and accordingly also detected by the evaluation.

In this case, a signal characterization is also preferably used to differentiate between the type of liquid. Such a sensor is in turn formed, for example, as an integrated sensor 20 in the cable 8 with the line element 16 (sensor line) into which a measuring pulse is fed. Its spread is characteristically changed in the presence of the liquid. Preferably, a further or a combined sensor is integrated, which is able to detect mechanical influences. Depending on the structure of the sensor 20 (line element 16) and / or by a suitable supply and evaluation of the supplied measuring pulse, in particular by a variably adjustable sampling frequency with which the measuring pulse is fed, the sensitivity of the sensor can be determined here be desired statement designed.

As an example, a change could be detected here from a permanent deformation (vehicle stands on the charging cable 8) to the dynamic detection of temporary bends (for example when plugged in).

In addition to the integrated sensor 20, a further external sensor 26 is preferably also provided in the charging system. This is, for example, a temperature sensor, which is preferably mounted in or on a charging plug, via which the charging cable 8 is connected to an energy source or energy sink.

As described above for the supply system, preferably a link to the external sensor 26 and / or further data sources is undertaken. On the one hand, this serves to check the plausibility of the signals generated by the internal sensor 20. On the other hand, knowledge about further dependencies and their effects on the charging cable (pattern recognition) are detected and determined via the further data sources or external sensors 26. From this then again the statements for the functional ability, eg an output improved and specified, for example, by an adjustment of the comparison system described above. In particular, a weather database for a currently prevailing ambient temperature is used as data sources. Alternatively or additionally, a charge control zb in the charging station or in the vehicle is used as an additional data source, are used in the charging process via the current and voltage waveforms.

By comparing the captured se- conon data with the above-described comparison system, statements about the functionality are made. For example, either ad hoc messages are generated in the event of critical states. In such a case, the charging system is preferably downshifted or switched off. That With the charging system, for example, the charging current is regulated as a function of the determined current state of the cable. In addition, creeping effects (continual signal drifts) are also preferably compensated with the comparison system and / or with historical measurement data from the sensors. Through a usage history, ie comparison with historical measurement data, on the basis of which statements about the previous use can be derived, forecasts are preferably derived for the (residual) service life. This helps to ensure a smooth loading operation.

The evaluation of a usage history specifically for a statement about a remaining service life is equally applied to the previously described supply system in the motor vehicle.

Overall, the monitoring of the supply system described here, especially of the monitored charging system, achieves both a high degree of operational safety and a high operational utilization of the supply system. Due to the particularly continuous monitoring, therefore, the entire supply system can be optimized and the safety margins in the structural design, such as conductor cross-sections ... can be reduced. The high level of safety ensures, in particular with the charging cable, that the user never comes into contact with an overheated or mechanically damaged cable. Furthermore, the charging processes can be optimized in order to achieve the highest possible degree of utilization for the operator (active control of charging and cooling processes).

In a preferred embodiment, an information exchange of the charging system is provided with other elements of a charging infrastructure. In particular, an exchange of information between the supply network (energy supplier) - charging station - charging cable - motor vehicle (inlet box, HV cabling up to the battery) is provided. This results in mutual dependencies, each leading to optimal utilization of the entire charging path. In this case, the states of the lines are seen as essential, controlling elements, both in the supply network, the charging line or the on-board network of the vehicle.

Claims

claims

1. A method for monitoring a supply system of a motor vehicle, in particular a high-voltage supply system of an electrically driven motor vehicle, comprising at least two electrical components connected via a cable, wherein the cable is part of the supply system, which further comprises a number of Has sensors for monitoring at least one state variable of the Versorgungssys- system, being closed on the basis of the values determined by the sensors for the state variable on the functioning of the supply system.

2. The method of claim 1, wherein the sensor is integrated in the cable.

3. The method of claim 1 or 2, wherein the sensor is formed by a line element of the cable, in which a sensor signal is fed and a response signal is evaluated.

4. The method of claim 3, wherein a plurality of individual measurements are carried out in the course of a measurement cycle, wherein

- the measurement signal is fed into the line element per individual measurement,

when a predetermined threshold value is exceeded as a result of the reflected measurement signal component, a stop signal is generated and the individual measurement is terminated in particular,

- A running time between the input of the measuring signal and the stop signal is determined, and

- Preferably, the threshold value between the individual measurements is changed.

5. The method as claimed in claim 4, wherein after a first stop signal has been detected in a first individual measurement, a second individual measurement with preferably the same threshold value as in the first individual measurement is undertaken, a measurement dead time being present in the second individual measurement. is given, which is greater than the detected during the first individual measurement runtime for the first stop signal, so that the first stop signal associated with the associated reflected component is not detected in the second single measurement.

6. The method according to any one of claims 1 to 5, wherein outside of the cable, an external sensor is arranged for detecting a state variable.

7. The method of claim 6, wherein the external sensor is a vibration sensor.

8. The method of claim 7, wherein the vibration sensor is disposed at a connection between the cable and one of the components.

9. The method according to any one of claims 2 to 7, wherein in addition to the im

Cable integrated sensor an external sensor is located outside the cable and a reading from the external sensor is evaluated in addition to the sensor integrated in the cable to indicate the current functioning of the power supply system.

10. The method of claim 9, wherein based on the measured value of the external sensor, a measured value obtained from the integrated sensor as i.O. or not i.O. is classified.

11. The method according to any one of claims 1 to 10, wherein the determined measured values for the state variables are compared with a comparison system and from this a statement about the functionality is made.

12. The method of claim 11, wherein the state variable for a plurality of supply systems detected, transmitted to a higher common common evaluation point and used for a modification of the comparison system.

13. The method according to any one of claims 1 to 12, wherein at least one further data source, such as a vehicle control, is used and considered for the assessment of the operability.

14. A method for monitoring a charging system of an electrically driven motor vehicle, comprising at least two electrical components connected to one another via a charging cable, namely a charging station and a battery, wherein the charging system supply system comprises a number of sensors for monitoring at least a state variable of the

Has on the basis of the values determined by the sensors for the state variable on the functioning of the charging system is closed.

15. The method of claim 14, wherein the charging cable is monitored by means of a built-in charging cable sensor on the temperature, mechanical loads and on the ingress of moisture.

16. The method of claim 14 or 15, wherein a charge control via a

Value via a current charging current or a current charging voltage, and these values are used to check the plausibility of the values determined by the sensors.

17. Method according to one of claims 14 to 16, in which an internal state variable, in particular temperature, is detected with a sensor integrated in the charging cable and in which by means of an external sensor a state variable outside the charging cable, in particular an ambient temperature is detected.