Monitoring device and method for monitoring a residual current protective device, system for monitoring residual current, and charging device for an electric vehicle

Abstract

The invention relates to the testing of a residual current protective device. For this purpose, according to the invention an external monitoring device periodically injects test signals into a sensor circuit of the residual current protective device, and evaluates the response of the residual current protective device to these test signals. The periodically injected test signals may have a signal duration which is shorter than the trip delay of the residual current protective device. Optionally, during an initialisation phase, test signals that have a signal duration longer than the trip delay of the residual current protective device may be injected.

Description

[0001] Description

[0002] title

[0003] Monitoring device and method for monitoring a residual current device, residual current monitoring system and charging device for an electric vehicle

[0004] Technical area

[0005] The present invention relates to a method for monitoring a residual current device and a monitoring device for a residual current device. The present invention further relates to a residual current monitoring system and a charging device for an electric vehicle with such a residual current monitoring system.

[0006] background

[0007] Residual current devices (RCDs) typically monitor a total current in a wiring arrangement with multiple electrical conductors, such as a forward conductor and a return conductor. If, in the event of a fault, the electrical current does not flow completely through this wiring arrangement to the consumer and back again, the residual current device can detect this through an increase in the monitored total current in the wiring arrangement and subsequently interrupt the power supply.

[0008] Since such residual current devices play a crucial role in personal protection, the correct functioning of such devices and the associated testing of their functionality are of paramount importance. For example, the publication DE 10 2009 001 962 A1 describes a charging system for an electric vehicle with a residual current device for monitoring fault currents during a charging process.

[0009] Disclosure of the invention

[0010] The present invention provides a method for monitoring a residual current device, a monitoring device for a residual current device, a system for monitoring residual current devices, and a charging device for an electric vehicle with the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

[0011] Accordingly, it is provided:

[0012] A method for monitoring a residual current device, wherein the residual current device comprises a sensor device, a measuring device, and a tripping device. The sensor device is designed to provide a sensor signal corresponding to a total current of a line arrangement with at least two electrical conductors. The measuring device is designed to determine a total current of the line arrangement using the sensor signal from the sensor device. The tripping device is designed to provide a tripping signal if the determined total current exceeds a predetermined threshold value. The method comprises a step for periodically feeding first test signals into a sensor circuit of the sensor device. Furthermore, the method comprises a step for receiving a measurement signal. The measurement signal corresponds to the total current determined by the measuring device.Finally, the method includes a step for checking the functionality of the residual current device. The functionality can be checked, in particular, using the received measurement signal.

[0013] Furthermore, it is planned:

[0014] A monitoring device for a residual current device, wherein the residual current device comprises a sensor device, a measuring device, and a tripping device. The sensor device of the residual current device is designed to provide a sensor signal corresponding to a total current of a line arrangement with at least two electrical conductors. The measuring device is designed to determine a total current of the line arrangement using a sensor signal from the sensor device. The tripping device is designed to provide a tripping signal. In particular, the tripping device can provide the tripping signal if the determined total current exceeds a predetermined threshold value. The monitoring device for the residual current device can be arranged outside the residual current device.In particular, the monitoring device can be designed to periodically feed first test signals into a sensor circuit of the sensor device. Furthermore, the monitoring device is designed to receive a measurement signal. The measurement signal can correspond to the total current determined by the measuring device. Furthermore, the monitoring device is designed to check the functionality of the residual current device. In particular, the monitoring device can check the functionality of the residual current device using the received measurement signal.

[0015] Furthermore, it is planned:

[0016] A system for residual current monitoring with a residual current device and a monitoring apparatus according to the invention. The residual current device comprises a sensor device, a measuring device, and a triggering device. The sensor device is designed to provide a sensor signal corresponding to a total current of a line arrangement with at least two electrical conductors. The measuring device is designed to determine a total current of the line arrangement. The total current can be determined in particular using the sensor signal from the sensor device. The triggering device is designed to provide a trigger signal if the determined total current exceeds a predetermined threshold.

[0017] Finally, it is planned:

[0018] A charging device for an electric vehicle comprising a charging circuit, a residual current monitoring system according to the invention, and a disconnecting device. The charging circuit is designed to be coupled to an electrical energy source by means of a cable arrangement with at least two electrical conductors. The disconnecting device is designed to interrupt an electrical connection between the electrical energy source and the charging circuit. The residual current monitoring system is designed to monitor the total current in the cable arrangement between the electrical energy source and the charging circuit.

[0019] Advantages of the invention

[0020] Residual current devices play a crucial role, especially for personal protection in electrical systems. It is therefore of utmost importance to ensure the correct functionality of such residual current devices. To this end, the residual current devices must be tested for correct functionality.

[0021] Based on this finding, the invention provides for a concept that can easily and reliably check the functionality of residual current devices, while ensuring high availability of the residual current device. For this purpose, an external device for monitoring or checking a residual current device is provided. By using such external devices for monitoring a residual current device, the monitoring according to the invention can be implemented using components with a high safety standard.

[0022] If the residual current device is used, for example, as part of a quality management (QM) concept, only a device certified according to the required safety standards can be used for monitoring. However, the sensor or residual current device itself does not necessarily have to include a sensor developed according to the safety standards.

[0023] In particular, for applications in the automotive sector, monitoring of the residual current device can be implemented using an external controller with a high safety classification, such as a high Automotive Safety Integrity Level (ASIL). For example, a controller with an ASIL-D classification is possible. The periodic input of externally generated test signals and the subsequent evaluation of signals from the sensor and measuring components of the residual current device enables continuous monitoring of the residual current device's functionality. In this way, the functionality of the monitored residual current device can be achieved with high reliability, especially during operation.If test signals are used for such a test of the residual current device which have a signal duration that is shorter than the tripping time of the residual current device, the functionality of the residual current device can be checked without causing an interruption in the circuit to be monitored.

[0024] A sensor circuit is a part of the sensor device that realizes the sensory detection of the total current in the line arrangement. For example, the sensor circuit in the sensor device can be implemented as a sensor coil. However, depending on the detection concept for the total current, other options for forming the sensor circuit for detecting the total current are also possible.

[0025] The residual current devices to be monitored can in particular be DC-sensitive residual current devices, for example type B or type B+ residual current devices.

[0026] According to one embodiment, the first test signals can comprise AC test signals and DC test signals. In particular, an AC test signal and a DC test signal can be provided alternately. In this way, it is possible to check the functionality of the residual current protective devices for both AC residual currents and DC residual currents.

[0027] According to one embodiment, the first test signals each have a signal duration that is shorter than a predetermined tripping delay of the residual current device. By providing such short test signals, the residual current device can be tested without triggering the residual current device. This makes it possible to continuously test the residual current device without interruption, even during operation.

[0028] According to one embodiment, the method further comprises a step for feeding second test signals into the sensor circuit of the sensor device. The second test signals can have a signal duration that is longer than the predetermined tripping delay of the residual current device. In other words, the second test signals have a signal duration that is intended to trigger the residual current device. Accordingly, the method further comprises a step for detecting a tripping of the residual current device. Furthermore, the method can comprise a step for checking the functionality of the residual current device, wherein the functionality is checked using the detected tripping of the residual current device. In this way, the response of the residual current device, including the complete tripping of the residual current device, can be checked.After functionality has been confirmed by the residual current device tripping, an interruption triggered by the residual current device can be automatically cleared. Similar to the first test signals, the second test signals can also each include at least one DC test signal and one AC test signal. This allows the correct tripping of the residual current device for DC and AC residual currents to be verified.

[0029] According to one embodiment, the second test signals have a signal duration that is shorter than a predefined maximum time period. In particular, the signal duration of the second test signals can be shorter than, for example, twice the predefined tripping delay of the residual current device. The signal duration can also be shorter, for example, than one and a half times the predefined tripping delay of the residual current device. In this way, it can be checked whether the residual current device reacts sufficiently quickly to a fault current.

[0030] According to one embodiment, the second test signals are fed in once in each initialization phase. Such an initialization phase can, for example, be an initialization phase of the residual current device. If the residual current device is used, for example, in the context of a charging device for an electric vehicle, its functionality can be checked by feeding in the test signals before the start of a charging process. It is also conceivable, for example, to perform an initialization each time the vehicle is started. In principle, however, other one-time approaches are also conceivable, in particular when a predetermined process for feeding in the second test signals is started.

[0031] According to one embodiment, checking the functionality of the residual current device comprises evaluating the magnitude of the total current during the injection of a first test signal, in particular a first test signal. By checking the magnitude of the reported total current transmitted by the residual current device to the external monitoring device and, if necessary, comparing it with the current injected by the test signal, further conclusions can be drawn regarding the functionality of the residual current device.

[0032] The above embodiments and further developments can be combined with one another as desired, where appropriate. Further embodiments, further developments, and implementations of the invention also include combinations of features of the invention not explicitly mentioned above or described below with respect to the exemplary embodiments. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

[0033] Short description of the drawings

[0034] Further features and advantages of the invention are explained below with reference to the figures.

[0035] Fig. 1: a schematic representation of a principle diagram for a system for residual current monitoring with a monitoring device according to an embodiment;

[0036] Fig. 2-5: Timing diagrams illustrating the principle for monitoring a residual current device; Fig. 6: a schematic representation of an implementation of a residual current monitoring system for a charging device in an electric vehicle; and

[0037] Fig. 7: a flowchart which may form the basis of a method for monitoring a residual current device according to one embodiment.

[0038] Description of embodiments

[0039] Figure 1 shows a schematic representation of a principle diagram of a residual current monitoring system according to one embodiment. The system comprises a residual current device 2 and a monitoring device 1. As can be seen in Figure 1, the monitoring device 1 can be provided outside the residual current device 2. The residual current device 2 does not necessarily have to have a sensor developed according to safety standards. In particular, it is possible for only the monitoring devices 1 to be developed or certified according to the required safety standards.

[0040] The monitoring device 1 can, for example, be implemented in an external control device. For example, the monitoring device 1 can be implemented at least partially by a controller, in particular an on-board controller of a motor vehicle, in particular an electric vehicle. Such an on-board controller can, for example, be designed or certified according to applicable safety standards, for example, safety requirements according to ASIL-D.

[0041] The cable arrangement 3 shown in Figure 1 can comprise at least two electrical conductors 31, 32. For example, one of the electrical conductors 32 can be a neutral conductor (N) and one of the electrical conductors 31 can be a phase conductor (LI). However, cable arrangements with more than two electrical conductors are also possible, for example, electrical conductors of a three-phase system with LI, L2, L3.

[0042] The residual current device 2 comprises a sensor device 21, a measuring device 22, and a tripping device 23. The sensor device 21 can detect a total current through the line arrangement 3. For example, the sensor device 21 can be a coil-like sensor device that detects the magnetic field around the entire line arrangement 3. Such a sensor coil thus encloses all electrical conductors 31, 32 of the line arrangement 3 and thus forms a sensor circuit around the line arrangement 3.

[0043] The sensor device 21 thus provides a sensor signal corresponding to the total current through the line arrangement 3. This sensor signal can be received by the measuring device 22. In particular, the measuring device 22 can determine the total current through the line arrangement 3, for example using the sensor signal from the sensor device 21. The measuring device 22 can then provide an output signal corresponding to the determined total current. This output signal can be provided, for example, to the triggering device 23. The triggering device 23 can receive the signal from the measuring device 22 and compare it with a predetermined triggering threshold. If the total current exceeds a predetermined threshold, for example, the triggering device 23 can provide a triggering signal. This triggering signal can, for example, trigger an interruption of at least one conductor 31, 32 in the line arrangement 3.In this way, a current flow through the line arrangement 3 can be interrupted if the total current through the line arrangement 3 exceeds a predetermined threshold value and thus at least part of the electrical current does not flow through the line arrangement 3 but via an alternative path.

[0044] When evaluating the total current, the fault current protection device 2 can, if necessary, distinguish between an alternating current component and a direct current component. In particular, different threshold values ​​for triggering by the triggering device 23 can be provided for alternating current and direct current, for example.

[0045] The monitoring device 1 comprises a test signal generator 11 and an evaluation device 12. The test signal generator 11 can generate predetermined test signals, in particular alternating current and direct current test signals, and feed them into the sensor circuit of the sensor device 21 of the residual current device 2 via a feed path 11a. In this way, the sensor device 21 of the residual current device 2 detects not only the total current of the electrical conductors 31, 32 of the line arrangement 3, but also an electrical current of the test signal generated by the test signal generator 11. As a result, the measuring device 22 of the residual current device 2 outputs a measured value that includes not only the total current of the line arrangement 3 but also the electrical current of the fed-in test signal.This value determined by the measuring device 22 of the residual current device 2 can be provided to the evaluation device 12 of the monitoring device 1. The evaluation device 12 can then evaluate the signal provided by the measuring device 22. In particular, the evaluation device 12 can check whether the signal provided by the measuring device 22 corresponds to the input test signal. In this case, the functionality of the residual current device can be confirmed. Otherwise, i.e., if the measurement signal output by the measuring device 22 deviates from the input test signal, the evaluation device 12 can detect a fault in the residual current device 2.

[0046] As explained in more detail below, the test signal generator 11 can generate various test signals and feed them into the sensor circuit of the sensor device 21. On the one hand, the test signal generator 11 can generate both alternating current and direct current test signals and feed them into the sensor circuit of the sensor device 21. In this way, the sensitivity of the residual current device 2 to alternating current and direct current faults can be tested. Furthermore, it is also possible to vary the signal duration of the test signals. On the one hand, test signals can be generated which are shorter than a tripping time of the residual current device 2. In this way, it is possible to at least partially test the residual current device 2 without the residual current device 2 triggering an interruption in the line arrangement 3.Furthermore, the test signal generator 11 can also provide test signals whose signal duration is longer than an expected tripping delay of the residual current device 2. In this way, such test signals will cause the residual current device 2 to trigger an interruption in the line arrangement 3. Thus, the complete function of the residual current device 2 up to the interruption of the line arrangement 3 can be checked using such test signals. In this case, the evaluation device 12 can also detect the tripping of the residual current device 2 and take this into account when checking the functionality of the residual current device 2. A check of the functionality using test signals that trigger the tripping of the residual current device 2 is generally carried out before or at the start of a desired operation that requires a current flow through the line arrangement 3.For example, during an initialization phase, a test signal can be generated and fed into the sensor circuit of the sensor device 21, which causes the residual current device 2 to trip. For example, at least one test signal for checking the AC sensitivity and one test signal for checking the DC sensitivity can be fed in. The signal duration of such test signals can, on the one hand, be selected to be long enough that tripping of the residual current device 2 is to be expected, i.e., the signal duration is longer than a tripping delay of the residual current device 2. Furthermore, the signal duration of such test signals can also be selected to be sufficiently short to check whether the residual current device 2 also responds sufficiently quickly.For this purpose, the signal duration of the test signals can, for example, correspond to a maximum length of twice the expected trigger delay or, if necessary, to a maximum of 1.5 times the expected trigger delay.

[0047] Test signals with a signal duration shorter than the tripping delay of the residual current device 2, however, do not trigger the residual current device 2 and thus do not cause an interruption in the line arrangement 3. Such short test signals can therefore also be fed in during operation, i.e., while a current is flowing through the line arrangement 3. In particular, such test signals can be fed in periodically, for example, in order to continuously check the functionality of the residual current device 2 during operation. For this purpose, alternating current and direct current test signals can be fed in alternately. For example, the test signals can be fed in periodically with a period of 100 milliseconds, 1 second, 1 minute, or any other time interval.In particular, it is also possible to configure the period duration for the periodic feeding of the test signals and to adapt it, for example, by means of appropriate parameterization in the evaluation device 12.

[0048] Figure 2 shows a timing diagram for a DC test signal IT without triggering the residual current device 2. The DC test signal IT has a current intensity whose value lies above the response threshold DC-S of the residual current device 2. The pulse duration Δt of the test signal is shorter than the response time tS of the residual current device 2. Due to delays in signal processing, the received output signal I_M from measuring device 22 is received with a time delay compared to the input test signal IT in the evaluation device 12. However, this time delay can be determined in advance and thus taken into account in the evaluation.

[0049] Figure 3 shows a timing diagram for testing a residual current device 2 with an alternating current test signal without tripping the residual current device 2. Analogous to the previously described case, an alternating current test signal IT is fed in, the current intensity of which lies above the response threshold AC-S of the residual current device 2. The signal duration Δt of the test signal IT is also shorter than the tripping delay tS of the residual current device 2. Thus, even when such an alternating current test signal IT is fed in, the residual current device 2 will not trip and thus interrupt the line arrangement 3.

[0050] Figure 4 shows a timing diagram for a DC test signal IT with a signal duration At that is longer than the tripping delay tS of the residual current device 2. Accordingly, after the time period tS corresponding to the tripping delay, the residual current device 2 will generate a tripping signal A to trigger an interruption of the line arrangement 3. Here, too, the tripping threshold is DC-S.

[0051] Finally, Figure 5 shows a timing diagram for the injection of an alternating current test signal IT with a signal duration that exceeds the tripping delay tS of the residual current device 2. Here, too, the current of the test signal IT is above the tripping threshold AC-S. Thus, after the tripping delay tS, the residual current device 2 will output a tripping signal A to trigger an interruption of the line arrangement 3.

[0052] Figure 6 shows a schematic representation of a charging device for an electric vehicle with a system for residual current monitoring according to one embodiment. An electrical energy source 200, in particular an alternating current source, can provide electrical energy, which is converted by means of a charging circuit 110 into an electrical voltage suitable for charging an electrical energy storage device 300, for example the traction battery of an electric vehicle. In this case, the previously described system 100 for residual current monitoring with a residual current protective device 2 and a monitoring device 1 can be provided in the line arrangement 3 between the electrical energy source 200 and the charging circuit 110. In such a configuration, for example, before or afterAt the beginning of the charging process, the functionality of the residual current device 2 is first checked using one or more test signals that trigger the residual current device to trip. In this way, the complete functionality of the residual current device 2 up to the interruption of the line arrangement 3 can be checked. During the energy transfer, i.e. during the charging process of the electrical energy storage device 300, the functionality of the residual current device 2 can then be checked by periodically feeding in test signals, wherein the test signals are sufficiently short not to trigger the residual current device 2. Such test signals can be fed in periodically at a predetermined frequency. In particular, for example, test signals with an alternating current test signal and a direct current test signal can be fed in alternately.In this way, the functionality of the residual current device can be continuously checked even during operation, i.e. during the charging process.

[0053] Figure 7 shows a flowchart that may form the basis of a method for monitoring a residual current device 2 according to one embodiment. In particular, the method can be applied to the previously described residual current device 2. The method can be implemented, for example, by the previously described monitoring device 1. Accordingly, the statements made previously in connection with Figures 1 to 6 also apply to the method described below. Conversely, the previously described components can also be designed to implement the method described below.

[0054] In a step Si 1, a first test signal can be fed into a sensor circuit of the sensor device 21 of the residual current device 2. Such a first test signal can, in particular, be a test signal whose signal length is shorter than the tripping delay of the residual current device 2. The current strength of the test signal can be above the tripping threshold of the residual current device 2. The test signal can be either an alternating current test signal or a direct current test signal. In particular, alternating current and direct current test signals can be fed in alternately. The test signals can be fed in periodically, in particular with a predetermined period or frequency.

[0055] In step S12, measurement signals corresponding to a determined total current are received. In particular, the measurement signals may correspond to a total current determined by a measuring device 22 of the residual current device 2.

[0056] Subsequently, in step S13, the functionality of the residual current device 2 can be checked. In particular, the functionality of the residual current device 2 can be checked using the received measurement signals.

[0057] Since the test signals used for steps SI 1 to S13 are above the tripping thresholds of the residual current device 2, but shorter than the tripping delay of the residual current device 2, it is expected that the residual current device 2 will not trigger an interruption of the line arrangement 3 with such test signals. Accordingly, the functionality of the residual current device 2 can be continuously checked by periodically feeding the test signals and subsequent evaluation.

[0058] Optionally, for example, during an initialization phase, the residual current device can be checked using further test signals, wherein the further test signals have a signal duration intended to trigger the residual current device 2. For this purpose, for example, in step S21, such a test signal can be fed into the sensor circuit of the sensor device 21 of the residual current device 2, which test signal has a signal duration that is longer than the specified or expected tripping delay of the residual current device 2. Subsequently, in step S22, tripping of the residual current device 2 can be detected, and in step S23, the functionality of the residual current device 2 can be checked. In particular, the check can be carried out using the detected tripping of the residual current device 2.The input of such test signals for triggering the residual current device 2 can be either an AC test signal or a DC test signal. In summary, the present invention relates to the testing of a residual current device. For this purpose, it is provided that, by means of an external monitoring device, test signals are periodically input into a sensor circuit of the residual current device and the response of the residual current device to these test signals is evaluated. The periodically input test signals can have a signal length that is shorter than a tripping delay of the residual current device. Optionally, test signals can be input during an initialization phase whose signal length is longer than the tripping delay of the residual current device.

Claims

Claims 1. Method for monitoring a residual current protective device (2) with a sensor device (21) which is designed to provide a sensor signal corresponding to a total current of a line arrangement (3) with at least two electrical conductors (31, 32), a measuring device (22) which is designed to determine a total current of the line arrangement (3) using the sensor signal from the sensor device (21), and a triggering device (23) which is designed to provide a triggering signal if the determined total current exceeds a predetermined threshold value, the method comprising the following steps: periodically feeding (Si l) first test signals into a sensor circuit of the sensor device (21); Receiving (S12) a measurement signal corresponding to the total current determined by the measuring device (22); and Checking (S13) the functionality of the residual current device (2) using the received measuring signal.

2. The method of claim 1, wherein the first test signals alternately comprise an AC test signal and a DC test signal.

3. Method according to claim 1 or 2, wherein the first test signals have a signal duration which is shorter than a predetermined tripping delay of the residual current protective device (2).

4. The method according to any one of claims 1 to 3, wherein the method further comprises the following steps: Feeding (S21) second test signals into the sensor circuit of the sensor device (21), wherein the second test signals have a signal duration which is longer than the predetermined tripping delay of the residual current protective device (2); Detecting (S22) a tripping of the residual current device (2); and Checking (S23) the functionality of the residual current device (2) using the detected tripping of the residual current device (2).

5. The method according to claim 4, wherein the second test signals have a signal duration which is shorter than a predetermined maximum time period, in particular shorter than twice the predetermined tripping delay of the residual current protective device (2).

6. The method according to claim 4 or 5, wherein the feeding (S21) of the second test signals takes place once in an initialization phase.

7. Method according to one of claims 1 to 7, wherein the checking (S13) of the functionality of the residual current protective device (2) comprises an evaluation of a level of the total current during the feeding (Si l) of a first test signal.

8. A monitoring device (10) for a residual current device (2) comprising a sensor device (21) designed to provide a sensor signal corresponding to a total current of a line arrangement (3) having at least two electrical conductors (31, 32), a measuring device (22) designed to determine a total current of the line arrangement (3) using the sensor signal from the sensor device (21), and a triggering device (23) designed to provide a triggering signal if the determined total current exceeds a predetermined threshold value, wherein the monitoring device (10) is arranged outside the residual current device (2) and is designed to periodically feed first test signals into a sensor circuit of the sensor device (21), to receive a measurement signal corresponding to the total current determined by the measuring device (22),and to check the functionality of the residual current device (2) using the received measuring signal., 9. A system (100) for residual current monitoring, comprising: a residual current device (2) with a sensor device (21) designed to provide a sensor signal corresponding to a total current of a line arrangement (3) with at least two electrical conductors (31, 32); a measuring device (22) designed to determine a total current of the line arrangement (3) using the sensor signal from the sensor device (21); a triggering device (23) designed to provide a trigger signal if the determined total current exceeds a predetermined threshold value; and a monitoring device (10) according to claim 8.

10. A charging device for an electric vehicle, comprising a charging circuit (110) designed to be coupled to an electrical energy source (200) by means of a line arrangement (3) with at least two electrical conductors (31, 32); a disconnecting device designed to interrupt an electrical connection between the electrical energy source (200) and the charging circuit (110); a system (100) for residual current monitoring according to claim 9, wherein the system (100) is designed to monitor a total current in the line arrangement (3) between the electrical energy source (200) and the charging circuit (110).

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