Method and device for monitoring a contactor

Abstract

The invention relates to a device for monitoring a switching process of a contactor, wherein the device is designed, for a measurement time, to determine a first measurement value of the potential on the first side of the contactor with the aid of a first measurement unit, and to determine a second measurement value of the potential on the opposite second side of the contactor with the aid of a second measurement unit. The device is also designed, at least for one of the measurement units, to determine a tolerance value of the measurement value measured by the associated measurement unit, the tolerance value depending on the measurement time, and to determine a voltage threshold value for the measurement time on the basis of the tolerance value for the measurement time. Furthermore, the device is designed to compare the potential difference determined on the basis of the first measurement value and on the basis of the second measurement value with the voltage threshold value in order to monitor the switching process of the contactor.

Description

[0001] 24-2590

[0002] Method and device for monitoring a contactor

[0003] The invention relates to a method and a corresponding device designed to monitor a switching operation of a contactor.

[0004] An electrically powered vehicle comprises an electric drive system with an electric motor that is powered by electrical energy from an electrical energy storage device. The nominal voltage of the energy storage device is typically in the high-voltage range, around 400V or more, or 800V or more. The drive system typically includes several contactors that can be opened as needed to galvanically isolate the electrical energy storage device from the drive system and / or the vehicle's charging interface, thus placing the vehicle in a safe (voltage-)safe state.

[0005] This document addresses the technical task of achieving particularly efficient, fast and reliable monitoring of a (switching operation of a) contactor.

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[0008] The problem is solved by each of the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It should be noted that additional features of a claim dependent on an independent claim, without the features of the independent claim itself or only in combination with a subset of the features of the independent claim, can constitute a separate invention independent of the combination of all features of the independent claim, which can be made the subject of an independent claim, a divisional application, or a subsequent application. This applies equally to technical teachings described in the description, which can constitute an invention independent of the features of the independent claims.

[0009] According to one aspect, a device for monitoring the switching operation of a contactor is described. The contactor can be arranged between an electrical energy source, in particular an electrical energy storage device, and an electrical load (e.g., an electric drive motor). The contactor can be configured to galvanically couple the electrical load to the energy source (in the closed state) or to galvanically decouple it from the energy source (in the open state). The contactor can be part of an electrically powered vehicle.

[0010] The first side of the contactor can face the voltage source, in particular the electrical energy storage device, especially such that a first potential induced by the voltage source is present on the first side of the contactor (which is typically essentially constant during a switching operation). The first potential can be 400 V or more, or 800 V or more.

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[0013] The opposite second side of the contactor can be facing away from the voltage source, in particular in such a way that

[0014] • during a closing operation of the contactor, the second potential on the second side of the contactor rises from an initial value, in particular from zero, to the first potential; and / or

[0015] • During the opening process of the contactor, the second potential on the second side of the contactor drops from the first potential to the output value, in particular to zero.

[0016] The second potential on the second side of the contactor can therefore change over time during a switching operation of the contactor.

[0017] The device is configured to determine, at a specific measurement point during the switching process, a first measurement of the (first) potential on the first side of the contactor using a first measuring unit. Furthermore, the device can be configured to determine, at the same measurement point, a second measurement of the (second) potential on the opposite second side of the contactor using a second measuring unit.

[0018] The measuring units typically exhibit a measurement inaccuracy (which may increase with age). As a result, the measured values ​​can deviate from the actual potential on the respective side of the contactor. The measurement inaccuracy of a measuring unit can be accounted for by a tolerance value that specifies the (maximum possible) deviation of the measured value from the actual potential.

[0019] The device is designed to determine a tolerance value for at least one of the measuring units (in particular the second measuring unit) of the measured value (in particular the second measured value) recorded by the respective measuring unit. The tolerance value for the respective

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[0022] The measurement time must be determined. In particular, the tolerance value can depend on the respective measurement time. The device can be configured to determine the tolerance value of the (second) measured value acquired by a measuring unit (especially by the second measuring unit) as a function of the measured value for the respective measurement time. By updating the tolerance value for the respective measurement time, particularly efficient, robust, and timely monitoring of the contactor can be achieved.

[0023] Typically, a tolerance value is determined for the measured values ​​of both measuring units. The tolerance value for the first measured value can remain essentially constant over time during a contactor switching operation (since the first potential is constant). Conversely, the tolerance value for the second measured value can change over time during the contactor switching operation (e.g., corresponding to the change in the second potential).

[0024] The device can be configured to determine a measurement tolerance function for a measuring unit (in particular for the second measuring unit), wherein the measurement tolerance function specifies a tolerance value for a multitude of different measured values. The measurement tolerance function can, for example, comprise a characteristic map, a lookup table, and / or an analytical function. The measurement tolerance function can be determined in advance (e.g., experimentally) and stored on a memory unit (of the vehicle).

[0025] The tolerance value of the (second) measured value recorded by the (second) measuring unit can be determined in a particularly precise and robust manner using the measurement tolerance function.

[0026] As previously explained, the measurement accuracy of a measuring unit can change over its lifetime. The device may be configured to store aging information related to its state of aging, particularly with regard to...

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[0029] The operating age of the (first or second) measuring unit (during the respective switching process) is to be determined. The measurement tolerance function for the (first or second) measuring unit can then be determined in a particularly precise manner depending on the aging information.

[0030] The device is further configured to determine a voltage threshold value for the measurement time based on the tolerance value (or values) for the measurement time. The voltage threshold value can be determined such that it increases or decreases with increasing (absolute) tolerance value.

[0031] The device can, for example, be configured to determine a constant base threshold value for the switching process for comparison with the potential difference (e.g., read from a memory unit). The base threshold value can be set in such a way that, assuming no measurement errors, the contactor can be monitored precisely and robustly by comparing the base threshold value with the measured potential difference (e.g., to determine the switching state of the contactor).

[0032] The (time-dependent) voltage threshold for the measurement time can then be precisely determined based on the constant base threshold and the time-dependent tolerance value for the measurement time, in particular by adding the tolerance value to the base threshold. In this way, a voltage threshold can be determined efficiently and precisely, taking into account measurement inaccuracies of the measuring units.

[0033] Furthermore, the device is configured to compare the potential difference determined based on the first and second measured values ​​with the voltage threshold value in order to monitor the switching operation of the contactor. The device can, in particular, be configured

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[0036] to determine, depending on the comparison of the potential difference with the voltage threshold for the respective measurement time, whether the contactor is in the closed state or in the open state at the respective measurement time.

[0037] The switching process can be an opening process, in which the contactor is moved from the closed state to the open state. The device can be configured to determine, based on a comparison of the potential difference at the measurement time with the voltage threshold value at the measurement time, whether the contactor is in the open state at that measurement time or not.

[0038] This describes a device that uses a time-dependent voltage threshold to monitor the switching operation of a contactor, in particular to determine the switching state of the contactor in a particularly robust and fast manner.

[0039] The device can be configured to determine, for a sequence of successive measurement points (during the switching process), the first and second measured values ​​for each measurement point and, based on these, the potential difference for each measurement point. Furthermore, the tolerance value for each measurement point and, based on this, the voltage threshold value for each measurement point can be determined (particularly based on a measured value for the respective measurement point). The (switching) state of the contactor at the respective measurement point can then be determined in a particularly robust, reliable, and fast manner by comparing the potential difference with the voltage threshold value for the respective measurement point.

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[0042] According to another aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described that includes the device described in this document.

[0043] According to one aspect, a method for monitoring the switching operation of a contactor (in a motor vehicle) is described. The method comprises (for a measurement point during the switching operation) determining, using a first measuring unit, a first measured value of the potential on a first side of the contactor, and determining, using a second measuring unit, a second measured value of the potential on an opposite second side of the contactor. Furthermore, the method comprises determining, at least for one of the measuring units, a tolerance value for the measured value acquired by the respective measuring unit, wherein the tolerance value depends on the measurement point (and thus changes during the switching operation). The method also comprises determining, based on the tolerance value for the measurement point, a voltage threshold value for the measurement point.Furthermore, the procedure includes comparing the potential difference determined on the basis of the first measured value and on the basis of the second measured value with the voltage threshold value in order to monitor the switching process of the contactor.

[0044] It should be noted that the aspects described in connection with the device, in particular the claims described in connection with the device, are also applicable to the method as corresponding process features.

[0045] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor (e.g., on a vehicle's control unit) and thereby execute the procedure described in this document.

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[0048] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0049] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways. Features listed in parentheses are to be understood as optional features.

[0050] The invention will now be described in more detail using exemplary embodiments.

[0051] Figure 1 shows exemplary components of a vehicle;

[0052] Figure 2a shows exemplary measuring units on a contactor;

[0053] Figure 2b shows exemplary time profiles of the potential difference and the voltage threshold during an opening process; and

[0054] Figure 3 shows a flowchart of an exemplary procedure for monitoring a contactor.

[0055] As stated at the outset, this document deals with the efficient, fast, and reliable monitoring of a contactor. In this context, Fig. 1 shows an exemplary vehicle 100 with an electrical energy storage device 104 for storing electrical energy for operating an electric drive motor (not shown) of the vehicle 100. The vehicle 100 typically includes an inverter 103, which is configured to convert the DC voltage provided by the energy storage device 104 into DC voltage.

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[0058] to convert it into a multi-phase alternating voltage for the operation of the electric drive motor.

[0059] The vehicle 100 further comprises at least one contactor 102 which is configured to establish (when the contactor 102 is closed) or to interrupt (when the contactor 102 is open) the electrically conductive connection between the electrical energy storage device 104 and the inverter 103.

[0060] A (control) device 101 of the vehicle 100 can be configured to cause the contactor 102 to be opened or closed.

[0061] In particular, the device 101 can cause the contactor 102 to be moved from the closed state to the open state in order to decouple the electrical energy storage device 104 from the inverter 103 and / or from the electric drive system of the vehicle 100, and thereby to bring the vehicle 100 into a safe state. It should be ensured that the contactor 102 is actually moved to the open state and does not remain in the closed state (e.g., because a mechanical part of the contactor 102 is jammed).

[0062] Fig. 2a shows an exemplary arrangement for monitoring the switching state of the contactor 102. The arrangement comprises a first measuring unit 201 on the first side of the contactor 102 (which, for example, faces the electrical energy storage device 102) and a second measuring unit 202 on the second side of the contactor 102 (which, for example, faces the inverter 103). The measuring units 201 and 202 are each configured to acquire measured values ​​with respect to the voltage potential at the respective measuring point (i.e., on the respective side of the contactor 102). Based on the difference in the measured values ​​at a specific measurement time, the potential difference, i.e., the voltage, across the contactor 102 at that specific measurement time can be determined.

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[0065] Fig. 2b shows exemplary time profiles of the voltage potential 210 (as a function of time 220) at the two measuring points of the two measuring units 201, 202 during an opening process in which the contactor 102 is moved from the closed state to the open state. At a first time point 221, when the contactor 102 is still closed, the two measuring points each exhibit a specific maximum potential (which corresponds, for example, to the voltage of the energy storage device 104, e.g., 400 V or more). The first measuring point (which faces the electrical energy storage device 104) also exhibits the maximum potential during the opening process and after the contactor 102 has opened, resulting in a constant profile 211 of the (first) potential at the first measuring point.

[0066] On the other hand, the (second) potential at the second measuring point decreases during the opening process to a minimum potential (e.g., zero), resulting in a decreasing profile 212 of the (second) potential at the second measuring point. Fig. 2b also shows the time course 213 of the potential difference (i.e., the difference between the (first) potential at the first measuring point and the (second) potential at the second measuring point). The potential difference increases during the opening process.

[0067] To monitor the opening process of contactor 102, the potential difference across contactor 102 can be compared with a voltage threshold. It can be determined that contactor 102 has successfully moved into the open state when, and especially as soon as, the potential difference reaches or exceeds the voltage threshold. Monitoring the potential difference ensures reliable and safe switching (especially opening) of contactor 102.

[0068] When determining the voltage threshold, the measurement accuracy of the measuring units 201 and 202 is typically taken into account. The measurement accuracy

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[0071] The accuracy of a measuring unit 201, 202 can be defined, for example, by a percentage value that indicates how much the actual value of the measured potential can deviate from the measured value recorded by the measuring unit 201, 202. For example, a measurement accuracy of x% can indicate that the actual value of the potential (with a certain probability, such as 99% or more) lies above or below the recorded measured value by at most a tolerance value of x% of the measured value.

[0072] To determine the voltage threshold S for monitoring the measured potential difference across the contactor 102, the maximum potential value Vmax, recorded by measuring units 201 and 202 during an opening operation, can be taken into account. Furthermore, a basic threshold B for the potential difference can be defined, at which (assuming no measurement inaccuracies) it can be assumed that the contactor 102 is reliably open. To account for the measurement inaccuracy of measuring units 201 and 202, this basic threshold B can be increased by the maximum possible measurement error or tolerance value x% * Vmax (for both measuring units 201 and 202), resulting in the voltage threshold S being: S = B + 2 * x% * Vmax. In this way, a constant voltage threshold S 214 can be provided for monitoring the opening operations of the contactor 102 (as shown in Fig. 2b).

[0073] The constant voltage threshold value 214 is relatively high, which means that the open state of the contactor 102, and thus the safe state of the vehicle's electrical drive system 100, can only be detected relatively late (e.g., at time 224). As can be seen in Fig. 2b, the measured value V recorded by the second measuring unit 202 decreases from the maximum value Vmax during the opening process over time 220. Consequently, the absolute value of the tolerance value, i.e., x%*V, also decreases over time 220. This fact can be taken into account to create a dynamic

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[0076] The goal is to determine the voltage threshold 215, which changes during the opening process. The dynamic voltage threshold 215 can be determined as S(t) = B + x%* Vmax + x%* V(t), where S(t) is the voltage threshold 215 at a specific time t, and where V(t) is the measured value of the second measuring unit 202 at that specific time t.

[0077] The function "x%*V(t)" is an example of a measurement tolerance function for a measurement unit 201, 202. The measurement tolerance function can specify a tolerance value for a large number of different measured values ​​of the measurement unit 201, 202, by which the recorded measured value can deviate from the actual potential.

[0078] As can be seen in Fig. 2b, the dynamic voltage threshold 215 decreases over time 220 during an opening process. This means that the potential difference crosses the dynamic voltage threshold 215 at time 225, which is before time 224, when the potential difference crosses the constant voltage threshold 214. The use of a dynamic voltage threshold 215 thus makes it possible to detect the open state of the contactor 102 and therefore the achievement of the safe state of the electrical drive system particularly early (without impairing the reliability of the detection).

[0079] When comparing voltages before and after a contactor (e.g., relay) 102, a threshold value 214, 215 can be used to detect that the contactor 102 is open. The threshold value 214, 215 influences how quickly and reliably the open state of the contactor 102 can be detected, which in turn affects the reliability and robustness of the detection and thus the supply of electrical energy to a vehicle 100.

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[0082] As explained above, a constant threshold value 214 can be defined, which takes into account the measurement tolerances of the different measuring units 201, 202. The calculation of the threshold value 214 is typically performed in advance and for different vehicle variants, which is relatively complex. Furthermore, degradation processes of an assembly (e.g., the aging of the insulation) are usually difficult to account for.

[0083] As described in this document, when determining the threshold value 215, the tolerance assumption of the one or more measuring units 201, 202 can be taken into account, so that the threshold value 215 can be dynamically adjusted and thus kept as small as possible, thereby reducing the detection time and / or increasing the robustness of the threshold value 215.

[0084] The measurement tolerance of a measuring unit 201, 202 can have an absolute component and / or a relative component. The relative component can refer to the maximum measurable measuring range (at the respective measurement time 220), whereby the measuring range can change during an opening process (i.e., over time 220). Thus, the measurement tolerances in the absolute "worst case" are not considered (as with the static threshold value 215), but rather the measurement tolerances at the respective measurement time 220 are considered, which can change (in particular, decrease) over time 220 during an opening process. Therefore, the measurement tolerances, and thus the threshold value 214, can be dynamically adjusted, in particular reduced, over time 220.This method of dynamically calculating the threshold value 214 can be flexibly adapted to different variants of an electric drive system and / or an electric energy storage device 104. Furthermore, aging effects can be efficiently taken into account (e.g., by adjusting the measurement tolerance of one or more parameters).

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[0087] several measuring units 201, 202 over the lifetime of one or more measuring units 201, 202).

[0088] Fig. 3 shows a flowchart of an exemplary (possibly computer-implemented) method 300 for monitoring a switching operation (in particular an opening operation) of a contactor 102 (of an electrically powered motor vehicle 100). The contactor 102 can be configured to decouple the electrical energy storage device 104 of the vehicle 100 from the electrical drive system of the vehicle 100 (in the open state of the contactor 102). The method 300 can be implemented by a control device 101 of the vehicle 100.

[0089] Method 300 comprises, for a measurement time 220 (during the switching operation of the contactor 102), determining 301, using a first measuring unit 201, a first measured value of the potential on a first side of the contactor 102, and determining 302, using a second measuring unit 202, a second measured value of the potential on an opposite second side of the contactor 102. Based on the first measured value and based on the second measured value, the potential difference across the contactor (for measurement time 220) can be determined, e.g., as the difference between the first and the second measured value.

[0090] Furthermore, the method 300 includes determining 303 a tolerance value for at least one of the measuring units 201, 202 of the measured value recorded by the respective measuring unit 201, 202. The tolerance value can depend on the measurement time 220. In particular, the tolerance value can be different for different measurement times 220. In one example, the second measured value changes during the switching process. The tolerance value for the second measured value can then change (e.g., depending on the second measured value, in particular proportionally to the second measured value).

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[0093] The tolerance value for the first measured value may change over time (220) during the switching process. On the other hand, it may remain constant over time.

[0094] The procedure 300 further includes determining 304, on the basis of the tolerance value (in particular on the basis of the tolerance values) for the measurement time 220, a voltage threshold value 215 for the measurement time 220.

[0095] For example, the determined tolerance value (or tolerance values) can be added to a (time-constant) basic threshold value to determine the stress threshold value 215.

[0096] Furthermore, the procedure 300 includes comparing 305 the potential difference determined on the basis of the first measured value and on the basis of the second measured value with the voltage threshold value 215 in order to monitor the switching operation of the contactor 102. Based on the comparison, it can be determined in particular whether the contactor 102 is in the open state or in the closed state at the measurement time 220.

[0097] The measures described in this document enable the state, in particular the open state, of a contactor 102 to be detected in a reliable, robust and fast manner.

[0098] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems by way of example.

[0099] January 10, 2025

Claims

24-2590 - 16 - Claims 1) Device (101) for monitoring a switching operation of a contactor (102); wherein the device (101) is configured for a measurement time (220), - to determine a first measured value of the potential on a first side of the contactor (102) using a first measuring unit (201); - to determine a second measured value of the potential on an opposite second side of the contactor (102) using a second measuring unit (202); - to determine a tolerance value for at least one of the measuring units (201, 202) of the measured value recorded by the respective measuring unit (201, 202); wherein the tolerance value depends on the measurement time (220); - to determine a voltage threshold value (215) for the measurement time (220) based on the tolerance value for the measurement time (220); and - to compare a potential difference determined on the basis of the first measured value and on the basis of the second measured value with the voltage threshold value (215) in order to monitor the switching process of the contactor (102). 2) Device (101) according to claim 1, wherein the device (101) is configured to determine the tolerance value of the measured value detected by a measuring unit (201, 202) as a function of the measured value. 3) Device (101) according to claim 2, wherein the device (101) is configured, 10.01.202524-2590 - 17 - - to determine a measurement tolerance function for a measuring unit (201, 202); wherein the measurement tolerance function specifies a tolerance value for a multitude of different measured values; and - to determine the tolerance value of the measured value recorded by the measuring unit (201, 202) using the measurement tolerance function. 4) Device (101) according to claim 3, wherein the device (101) is configured, - To determine aging information relating to an aging state, in particular in relation to an operating age, of the unit of measurement (201, 202); and - to determine the measurement tolerance function for the measuring unit (201, 202) depending on the aging information. 5) Device (101) according to one of the preceding claims, wherein the device (101) is configured to determine, depending on the comparison of the potential difference with the voltage threshold value (215) for the measurement time (220), whether the contactor (102) is in a closed state or in an open state at the measurement time (220). 6) Device (101) according to one of the preceding claims, wherein the device (101) is configured for a sequence of successive measurement times (220) each, - to determine the first and second measured values ​​for the respective measurement time (220) and, based on these, the potential difference for the respective measurement time (220); - in particular based on a measured value for the respective measurement time (220), the tolerance value for the respective measurement time (220) and based on this the voltage- 10.01.202524-2590 - 18 - to determine the threshold value (215) for the respective measurement time (220); and - to determine the state of the contactor (102) at the respective measurement time (220) based on the comparison of the potential difference with the voltage threshold value (215) for the respective measurement time (220). 7) Device (101) according to one of the preceding claims, wherein the device (101) is configured, - to determine a constant basic threshold value for the switching process for comparison with the potential difference; and - to determine the voltage threshold (215) for the measurement time (220) on the basis of the constant basic threshold and on the basis of the time-dependent tolerance value for the measurement time (220), in particular by adding the tolerance value to the basic threshold. 8) Device (101) according to one of the preceding claims, wherein - the switching operation is an opening operation in which the contactor (102) is moved from the closed state to the open state; and - the device (101) is set up to determine, on the basis of comparing the potential difference for the measurement time (220) with the voltage threshold value (215) for the measurement time (220), whether the contactor (102) is in the open state at the measurement time (220) or not. 9) Device (101) according to one of the preceding claims, wherein - the first side of the contactor (102) faces a voltage source, in particular an electrical energy storage device (104), 10.01.202524-2590 - 19 - in particular such that a first potential caused by the voltage source is present on the first side of the contactor; - the second side of the contactor (102) is turned away from the voltage source, in particular such that -during a closing operation of the contactor (102), the potential on the second side of the contactor (102) rises from an initial value, in particular from zero, to the first potential; and / or -during an opening operation of the contactor (102), the potential on the second side of the contactor (102) drops from the first potential to the output value, in particular to zero; and - the tolerance value of the second measurement value recorded by the second measuring unit (202) depends on the measurement time (220) and / or on the second measurement value. 10) Method (300) for monitoring a switching operation of a contactor (102); wherein the method (300) comprises, for a measurement time (220), - determining (301), using a first measuring unit (201), a first measured value of the potential at a first side of the contactor (102); - Determine (302), using a second measuring unit (202), a second measured value of the potential on an opposite second side of the contactor (102); - Determine (303) at least for one of the measuring units (201, 202) a tolerance value of the measured value recorded by the respective measuring unit (201, 202); wherein the tolerance value depends on the measurement time (220); - Determine (304), based on the tolerance value for the measurement time (220), a voltage threshold value (215) for the measurement time (220); and 10.01.202524-2590 - 20 - - Comparing (305) a potential difference determined on the basis of the first measurement and on the basis of the second measurement with the voltage threshold (215) to monitor the switching operation of the contactor (102).

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