DEVICE AND METHOD FOR MONITORING A HIGH-VOLTAGE CONTACTOR IN A VEHICLE

Abstract

The present disclosure relates to a device for monitoring a high-voltage contactor in a vehicle. In one implementation, the high-voltage contactor has a coil with an anchor, the coil is energized with a coil current or a coil voltage to switch the high-voltage contactor, and the high-voltage contactor is switched by a motion of the anchor, thus also changing the inductivity of the coil. The device may include an interface for reading in a measurement value function for the generated coil voltage and/or for the generated coil current during the switching cycle of the high-voltage contactor; an analysis device for determining a motion information representing a travel distance of the anchor based on the measurement value function; and a comparison device for comparing the motion information with a threshold value information. A fault signal is generated when the motion information falls below the threshold information.

Claims

1-7. (canceled)

8. A device for monitoring a high-voltage contactor having a coil and an anchor, wherein the coil is configured to be energized with a current or a voltage, and wherein the anchor is configured to switch the contactor by traveling between plural positions, the device comprising: an interface configured to detect a measurement value function, reflecting a signal value of at least one of the coil current or the coil voltage with respect to time, during a switching cycle of the contactor; an analysis device configured to determine motion information representing a distance traveled by the anchor based on the detected measurement value function; and a comparison device configured to compare the motion information to a threshold and to generate a fault signal when the motion information exceeds the threshold.

9. The device of claim 8, wherein the analysis device is further configured to determine the motion information based on a signal segment of the measurement value function.

10. The device of claim 9, wherein the analysis device is further configured to analyze the signal segment of the measurement value function for at least one of a local maximum or a local minimum.

11. The device of claim 10, wherein the analysis device is further configured to determine the motion information based on a ratio of a signal spacing between the local maximum and the local minimum to a height of the signal segment, wherein the height of the signal segment represents an amplitude range of the signal segment.

12. The device of claim 8, wherein the measurement value function represents a current function of the coil current.

13. The device of claim 9, wherein the threshold comprises a percentage of a height of the signal segment, wherein the height of the signal segment represents an amplitude range of the signal segment.

14. The device of claim 13, wherein the threshold comprises at least 5% of the signal segment height.

15. The device of claim 13, wherein the threshold comprises at least 10% of the signal segment height.

16. The device of claim 10, wherein the analysis device is further configured to determine the motion information based on a time differential between the local maximum and the local minimum and a time span of the signal segment.

17. The device of claim 8, wherein the threshold comprises a value band, wherein the value band comprises an ideal measurement value function having a tolerance range.

18. A method for monitoring a high-voltage contactor having a coil and an anchor, wherein the coil is configured to be energized with a current or a voltage, and the wherein the anchor is configured to switch the contactor by traveling between plural positions, the method comprising: detecting a measurement value function, reflecting a signal value of at least one of the coil current or the coil voltage with respect to time, during a switching cycle of the contactor; determining motion information representing a distance traveled by the anchor based on the measurement value function; comparing the motion information to a threshold; and generating a fault signal when the motion information exceeds the threshold.

19. The method of claim 18, further comprising at least one of filtering or smoothing the measurement value function before determining motion information based on the measurement value function.

20. The method of claim 18, wherein determining motion information further comprises analyzing a signal segment of the measurement value function for at least one of a local maximum or a local minimum.

21. The method of claim 20, wherein determining motion information further comprises determining motion information based on a ratio of a signal spacing between the local maximum and the local minimum to a height of the signal segment, wherein the height of the signal segment represents an amplitude range of the signal segment.

22. The method of claim 18, wherein the measurement value function represents a current function of the coil current.

23. The method of claim 18, wherein the threshold comprises a percentage of a height of the signal segment, wherein the height of the signal segment represents an amplitude range of the signal segment.

24. The method of claim 23, wherein the threshold comprises at least 5% of the signal segment height.

25. The method of claim 20, wherein determining motion information further comprises determining motion information based on a time differential between the local maximum and the local minimum and a time span of the signal segment.

26. The method of claim 18, wherein the threshold comprises a value band, wherein the value bank comprises an ideal measurement value function having a tolerance range.

27. A non-transitory, computer-readable medium storing instructions for monitoring a high-voltage contactor having a coil and an anchor, wherein the coil has a current or a voltage, and the anchor is configured to switch the contactor, the instructions comprising: reading a measurement value function, reflecting a signal value of at least one of the coil current or the coil voltage with respect to time, during a switching cycle of the contactor; determining motion information representing a distance traveled by the anchor based on the measurement value function; comparing the motion information to a threshold; and generating a fault signal when the motion information exceeds the threshold.

Description

BRIEF DESCRIPTION OF FIGURES

[0026] FIG. 1 shows a schematic representation of a device for monitoring a high-voltage contactor in a vehicle in accordance with an exemplary embodiment of the present disclosure.

[0027] FIG. 2 shows a schematic representation of a method for monitoring a high-voltage contactor in a vehicle in accordance with an exemplary embodiment of the present disclosure.

[0028] FIG. 3 through FIG. 4 show measurement value functions for the generated coil current (I) during the switching cycle of various high-voltage contactors.

[0029] FIG. 5 through FIG. 6 show measurement value functions for the generated coil voltage (U) during the switching cycle of various high-voltage contactors.

[0030] FIG. 7 through FIG. 10 each show a measurement value function of a coil current.

[0031] FIG. 11 through FIG. 18 show measurement value functions for the generated coil voltage (U) and/or for the corresponding coil current (I) during the switching cycle of various high-voltage contactors.

[0032] The following provides a detailed description of the embodiments according to the present disclosure based on the figures and at least one exemplary embodiment.

[0033] FIG. 1 shows a schematic representation of an exemplary embodiment for a device 100 for monitoring a high-voltage contactor 110 in a vehicle 140. The vehicle 140 may be a hybrid vehicle 140, a plug-in and/or a purely electrical vehicle 140, or a fuel-cell vehicle 140. The (high-voltage) on-board power system 124 of the vehicle 140 has a voltage greater than 60 Volts direct current (VDC), in particular greater than 480 VDC. In an additional exemplary embodiment, the vehicle has an additional (not shown) low-voltage on-board power system with 12 VDC, 24 VDC or 48 VDC.

[0034] The high-voltage contactor 110 has a coil 112 and an anchor 114, wherein the anchor 114 is movably arranged in the coil 112. The anchor 114 is furthermore coupled with a switching element 132, which in a switched position 136 electrically connects a first contact 128 with a second contact 130. The contacts 128 and 130 are part of the high-voltage on-board power system 124 of the vehicle 140. When the high-voltage contactor 110 is closed, the high-voltage on-board power system 124 is therefore closed and under voltage. In this case, the anchor 114 and/or the switching element 132 coupled thereto is movable between the switched position 132 and an idle position 134. The anchor travels the travel distance 126 between the two positions 128, 130. The coil current I or the coil voltage U can be tapped on the connections of the coil 112.

[0035] The device 100 encompasses an interface for reading in a measurement value function 106, an analysis device 104, and a comparison device 116. The measurement value function 106 represents a signal of the coil current I or of the coil voltage U of the high-voltage contactor. In the shown embodiment, the device 100 also features an optional measurement device 122 arranged to record the coil current I and, at the same time or alternatively, to record the coil voltage U, and to make these available as a measurement value function 106. The measurement value function represents the coil current I and/or the coil voltage U over time. The individual measurement values will generally be polled equidistantly.

[0036] Interface 102 may be used to read the measurement value function 106 into the device 100. The analysis device 104 may be arranged to process the measurement value function 106 and to determine motion information 108. The motion information in this case represents the travel distance 126 covered by the anchor 114 over time. Depending on the embodiment, the analysis device 104 encompasses various functions for this purpose to qualitatively or quantitatively determine the motion information.

[0037] The comparison device 116 compares the motion information 108 with threshold information 118 and provides a fault signal 120 based on the results of the comparison. In other words, the threshold information 118 represents comparison information. For example, when motion information 108 is an individual motion value that represents the travel distance, threshold information 118 correspondingly represents an individual threshold value. As will be shown in other embodiments, motion information 108 may also represent a motion over time. In the latter case, threshold information 118 then also represents a signal over time.

[0038] As already indicated, depending on the embodiment, measurement value function 106 may represent a current function of the coil current I over time or alternatively may represent the coil voltage U over time when the high-voltage contactor 110 is either switched on or off. In one embodiment, both signals are monitored during both switching cycles, thus increasing the analysis certainty and allowing faults to be detected at an early stage. Corresponding stuck contactors may then be detected when they occur and not only during one of the following switching cycles.

[0039] In another embodiment, the analysis device 104 may be arranged to analyze the flank of measurement value function 106. This involves examining the flank for local maximums and local minimums. If no local maximum and no local minimum is found, this indicates a fault event. The identified local maximums and minimums are then analyzed further. The measurement value function in FIG. 3 shows a characteristic signal collapse in the flank, which differs according to the applied voltage and the employed high-voltage contactor.

[0040] In one embodiment, motion information 108 may be determined as a function of the signal spacing between the characteristic local maximum and the corresponding local minimum. Depending on the embodiment, this may be set in relation to the flank height or alternatively to the duration of the time interval of the flank. Threshold value information 118 may be defined in the corresponding embodiments in percentage of the flank height or the corresponding time interval, e.g. 5%, 10%, 15% or 20%. This may be done in direct dependence on the examined high-voltage contactor 110. In an alternative embodiment, pre-defined threshold values are monitored for the local maximum, and additionally or alternatively, for the local minimum. This may be easily and cost-effectively accomplished in a simple comparison in an ASIC or by a comparator circuit for an analog analysis.

[0041] In yet another embodiment, threshold value information 118 represents a threshold value band. The comparison device 116 in this embodiment may be arranged to compare motion information 108 with the threshold value band. Since the flank of measurement value function 106 already represents the motion of the anchor 114, measurement value function 106 may be compared with a threshold value band, and fault signal 120 may be generated when the examined signal 106 or 108 leaves the threshold value band.

[0042] FIG. 2 shows a method 200 for monitoring a high-voltage contactor in a vehicle in accordance with an embodiment of the present disclosure. The vehicle may be a version of a vehicle 140 shown in FIG. 1. Accordingly, the device 100 shown therein may be equipped with devices for executing the steps of the method 200 shown here.

[0043] The method 200 has step S1, reading in a measurement value function for the corresponding coil voltage (U) and/or the resulting coil current (I) during a switching cycle of the high-voltage contactor; step S2, determining a motion information representing a travel distance of the anchor based on the measurement value function; and step S3, comparing the motion information with a threshold value information, wherein a fault signal is generated when the motion information falls below the threshold value information.

[0044] In an optional embodiment, method 200 features an additional, not shown step, filtering or smoothing the measurement value function before the analysis for the purpose of concealing and/or filtering out small signal changes from the subsequent analysis.

[0045] FIG. 3 through FIG. 6 show measurement value functions 322 for the generated coil current (I) during the switching cycle of various high-voltage contactors. In this example, the measurement value functions 322 correspond to the measurement value functions labeled in FIG. 1 with the identifier 106. The signal 323 additionally shows the electrical state of the switching contacts of the high-voltage contactor. A Cartesian coordinate system represents the time on the abscissa and the voltage and/or current on the ordinate. The measurement value function 320 represents a voltage signal 320 or a function of the coil voltage over time, the measurement value function 322 represents a current signal 322 or a current function 322 of a coil current of the high-voltage contactor.

[0046] In the embodiment shown in FIG. 3, the identifier 324 identifies the signal segment of the voltage signal 320 designated as the flank 324. The flank 324 has a time duration of Δt.sub.1. The flank 324 has a local maximum 326 and a local minimum 328. The flank height or the signal swing are labeled with the identifier 330. The time duration Δt.sub.2 identifies the time interval or the duration between the occurrence of the local maximum 326 and the local minimum 328.

[0047] The change in the coil inductivity caused by the unidirectional motion of the anchor into and out of the coil results in a signal collapse within the (rising) flank 324 of the voltage signal 320. The duration Δt.sub.2 in this exemplary embodiment is approximately 15%-20% of the time duration Δt.sub.1 of the flank 324. The signal spacing between the local maximum 326 and the local minimum 328 in relation to the flank height 330 is at least 60% in the embodiment shown in FIG. 3.

[0048] Possible parameters for detecting a proper function are the start of the collapse, the duration of the collapse, and the current differential of the collapse. While these parameters of course vary depending on the employed contactor, they may nevertheless be defined for any contactor. The contactor state may be defined without the need for making modifications on the contactor (e.g. additional diagnostic contact).

[0049] FIG. 3 shows the function of the coil current 322 during the switch-on cycle, and FIG. 4 shows the function of the coil current 322 during the switch-off cycle of the high-voltage contactor. FIG. 4 shows that the anchor motion energy during the opening phase causes the current to rise during the switch-off cycle.

[0050] In FIG. 4, the measurement value function 322 remains within a threshold value band 432. In this embodiment, the threshold value information may be represented as a threshold value band 432. The motion information may be represented by the measurement value function 322. It is then easy to examine whether the measurement value function 322 remains within the threshold value band 432. A fault signal is generated when the measurement value function 322 leaves the threshold value band.

[0051] In certain aspects, the threshold value band 432 corresponds to an ideal measurement value function 322 with a pre-defined tolerance range.

[0052] FIG. 5 shows a defective high-voltage EVC500 contactor during the switch-on cycle, and FIG. 6 shows the same defective EVC500 contactor during the switch-off cycle. The clearly evident collapse of the current function 322 during the flank 324 as shown in FIG. 3 and FIG. 4 does not occur.

[0053] FIG. 7 through FIG. 10 each show a measurement value function 322 of a coil current 322 for various high-voltage contactors. FIG. 7 shows a coil current 322 during a switch-on cycle for a HFE18V-40 high-voltage contactor, FIG. 8 for a EVC175 high-voltage contactor, FIG. 9 for a EVC250 high-voltage contactor, and FIG. 10 for a EVC500 high-voltage contactor.

[0054] The embodiments shown herein allow the coil current 322 during the closing cycle to be monitored with relatively little effort. As the anchor moves, the coil inductivity changes since different anchor lengths are located in the area of the coil's electro-magnetic field. The motion of the anchor in the coil causes a signal collapse of the current signal. The described effects cause a significant collapse of the coil current 322 shortly after the coil is energized. This may be easily detected with little effort by means of software or a corresponding device, for instance in the form of an ASIC. In the event of a stuck contactor (even for a single-sided stuck contactor), the anchor will exhibit no or only little motion. This results in a different coil current function 322 during the switch-on cycle. The diagnosis may be performed on every closing cycle.

[0055] FIG. 11 through FIG. 18 show measurement value functions 106 for the corresponding coil voltage (U) and/or for the corresponding coil current (I) during the switching cycle of various high-voltage contactors.

[0056] The following figures are based on a test-stand setup wherein the contactor to be examined was directly energized with the power supply. The following measurements therefore did not involve the use of electronics. The coil current was recorded with a current probe.

[0057] FIG. 11 shows a current function 322 for a defective EVC250 high-voltage contactor during the switch-on cycle, and FIG. 12 shows a current function 322 for the same defective high-voltage contactor during the switch-off cycle.

[0058] FIG. 13 shows a current function 322 for an intact EVC250 high-voltage contactor during the switch-on cycle. During the switch-on cycle, the current collapses after approximately 9.5 ms for a duration of 5 ms, before rising to the maximum value. This is the expected behavior, which may be verified by a diagnostic function. FIG. 14 shows a current function 322 of the same intact high-voltage contactor during the switch-off cycle. The coil current also rises once again during the switch-off cycle as the anchor drops back. If the electronics are developed in a manner that the coil current may also be measured during the switch-off cycle, a stuck contactor may already be directly detected during the switch-off cycle.

[0059] Depending on the circuit, the voltage across the coil may also be used for the diagnostic function during the switch-off cycle. In the extreme cases shown in FIG. 15 and FIG. 16, the wire to the contactor was subjected to a hard interruption, thus causing the coil current to instantly go to 0 A. However, an inductive voltage that is also dependent on the anchor motion is generated in this case.

[0060] FIG. 15 and FIG. 16 show a defect-free EVC250 high-voltage contactor. FIG. 15 shows the measurement value function 106 of the coil voltage 320 during the switch-on cycle, and during the switch-off cycle in FIG. 16.

[0061] In the same manner, FIG. 17 and FIG. 18 show a defect-free high-voltage contactor of type EVC500.

LIST OF IDENTIFIERS

[0062] 100 Device [0063] 102 Interface for reading in [0064] 104 Analysis device [0065] 106 Measurement value function [0066] 108 Travel distance [0067] 110 High-voltage contactor [0068] 112 Coil [0069] 114 Anchor [0070] I Coil current [0071] U Coil voltage [0072] 116 Comparison device [0073] 118 Threshold value [0074] 120 Fault signal [0075] 122 Measurement device [0076] 124 High-voltage on-board power system [0077] 126 Travel distance [0078] 128 First contact [0079] 130 Second contact [0080] 132 Switching element [0081] 134 Idle position [0082] 136 Switched position [0083] 140 Vehicle [0084] 200 Method [0085] S1 Reading in step [0086] S2 Determination step [0087] S3 Comparison step [0088] 320 Measurement value function, voltage signal [0089] 322 Measurement value function, current signal, current function of a coil current [0090] 323 electrical state of the switching contacts [0091] 324 Flank [0092] 326 local maximum [0093] 328 local minimum [0094] 330 Signal swing, flank height [0095] Δt.sub.1 Time duration of the flank [0096] Δt.sub.2 Time duration [0097] 432 Threshold value band