Switching device and method for monitoring a switching device

Abstract

A switching device (10) comprises a main switch (11), a coil (12), a control circuit (13), a state diagnostic circuit (15) and a failure diagnostic circuit (16). The coil (12) is coupled to the main switch (11). The control circuit (13) has a coil control circuit (14) coupled to the coil (12). The state diagnostic circuit (15) has an input coupled to the main switch (11). The failure diagnostic circuit (16) has an input side coupled to the control circuit (13). Moreover, a method for monitoring a switching device (10) is provided.

Description

[0001] P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0002] 1

[0003] Description

[0004] SWITCHING DEVICE AND METHOD FOR MONITORING A SWITCHING DEVICE

[0005] TECHNICAL FIELD

[0006] The disclosure is related to a switching device and a method for monitoring a switching device .

[0007] BACKGROUND

[0008] The switching device is realized as electromechanical device which is electrically controlled. The switching device is arranged e . g. between a battery or a power source and a load. Such a switching device may show a failure .

[0009] It is an obj ective of the present application to provide a switching device and a method for monitoring a switching device that detects a failure of the switching device .

[0010] This obj ective is achieved by the subj ect-matter of the independent claims . Further embodiments and developments are given in the dependent claims .

[0011] SUMMARY

[0012] In an embodiment, a switching device comprises a main switch, a coil, a control circuit with a coil control circuit, a state diagnostic circuit and a failure diagnostic circuit . The coil is coupled to the main switch. The coil control circuit is coupled or connected to the coil . The state diagnostic circuit comprises an input coupled to the mainP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0013] 2

[0014] switch. The failure diagnostic circuit comprises an input side coupled to the control circuit .

[0015] Advantageously, the state diagnostic circuit and the failure diagnostic circuit are configured to provide information about a state of the switching device and about a failure inside the switching device .

[0016] In an embodiment of the switching device, the state diagnostic circuit is configured to provide a state signal as a function of a state of the main switch.

[0017] Advantageously, the state signal can be used as feedback of the switching device showing the state of the switching device .

[0018] In an embodiment of the switching device, in a first state, the main switch is in a closed or conducting position. In the first state, a load current can flow through the main switch. In a second state, the main switch is in an open or nonconducting position. In the second state, no load current flows through the main switch.

[0019] In an embodiment, the switching device further comprises a mirror switch which is mechanically connected to the main switch. The mirror switch is configured to change its state in case the main switch changes its state .

[0020] In an embodiment of the switching device, the state diagnostic circuit is coupled or connected to the mirror switch. The state diagnostic circuit is configured to provide the state signal with a first value in case the mirror switch is in a conducting position and with a second value in caseP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0021] the mirror switch is in a non-conducting position. In the conducting position, the mirror switch is in a closed position. In the non-conducting position, the mirror switch is in an open position.

[0022] In an embodiment of the switching device, the main switch comprises a first and a second fixed contact, a contact bridge, and a first and a second movable contact which are arranged at the contact bridge . The main switch comprises an armature . The armature is coupled or connected to the coil and to the contact bridge . The coil is realized as magnetic drive . The coil provides a force on the armature . The force results in a movement of the armature which directly or indirectly moves the contact bridge . In an example, the switching device comprises a spring coupling the armature to the contact bridge and thus realizing an indirect move of the contact bridge by the armature . Thus, the coil is coupled to the main switch.

[0023] In an embodiment of the switching device, the armature of the main switch is mechanically connected to an armature of the mirror switch. Thus, both armatures are moved by the coil in the same direction. Alternatively, the contact bridge of the main switch is mechanically connected to a contact bridge of the mirror switch. Thus, both contact bridges are moved by the armature in the same direction. Thus, the state signal which informs about the position of the mirror switch indicates the position which the main switch should have in the absence of a failure . A failure could be e . g. a melting of contacts caused by an arc . For example, the state signal is a digital signal . For example, the state signal comprises one bit . In an example, the state signal is a pulse-width modulated signal or a bus signal .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0024] In an embodiment of the switching device, the failure diagnostic circuit is configured to provide a failure signal as a function of a failure or of at least a failure detected in or by the control circuit . The failure signal is generated in case of at least one failure . Different failures are monitored and can be reported by the failure signal . For example, the failure signal is a digital signal . For example, the failure signal comprises at least one bit . In an example, the failure signal comprises more than one bit or more than two bits or more than three bits . In an example, the failure signal is a pulse-width modulated signal or a bus signal .

[0025] Advantageously, the failure signal can be used as feedback of the switching device showing the presence or absence of a failure of the switching device .

[0026] In an embodiment of the switching device, the control circuit further comprises a first current sensor and a current measurement monitoring circuit . The first current sensor is coupled or connected to an input of the coil control circuit . The first current sensor is configured to provide a first current signal by detecting or measuring a load current that flows through the main switch. An input of the current measurement monitoring circuit is coupled or connected to the first current sensor . The current measurement monitoring circuit is configured to generate a current sensor monitoring signal as a function of at least the first current signal . An output of the current measurement monitoring circuit is coupled or connected e . g. to the input side of the failure diagnostic circuit . The output of the current measurement monitoring circuit is coupled or connected e . g. to an input of the coil control circuit .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0027] - 5 -

[0028] In an embodiment of the switching device, the control circuit further comprises a second current sensor configured for providing a second current signal by detecting or measuring the load current that flows through the main switch. A further input of the current measurement monitoring circuit is coupled or connected to the second current sensor . The current measurement monitoring circuit is configured to generate the current sensor monitoring signal as a function of the first current signal and of the second current signal .

[0029] For example, the first current sensor and the second current sensor are serially connected to the main switch. The load current flows through the first current sensor, the second current sensor and the main switch.

[0030] In an embodiment of the switching device, the control circuit further comprising a coil de-energizing monitoring circuit which comprises an input coupled or connected to the coil . The coil de-energizing monitoring circuit is configured to provide a coil monitoring signal as a function of a voltage or a current provided at the coil .

[0031] In an embodiment of the switching device, an output of the coil de-energizing monitoring circuit is coupled or connected to the input side of the failure diagnostic circuit . The failure diagnostic circuit is configured to provide the failure signal as a function of the coil monitoring signal . The output of the coil de-energizing monitoring circuit is coupled or connected e . g. to an input of the coil control circuit .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0032] 6

[0033] In an embodiment of the switching device, the control circuit further comprises a power supply circuit and a coil power supply monitoring circuit . The power supply circuit is coupled or connected to a supply input of the coil control circuit . The power supply circuit is configured to provide a supply voltage . The coil power supply monitoring circuit is coupled or connected to the power supply circuit . The coil power supply monitoring circuit is configured to provide a fast-off signal as a function of the supply voltage .

[0034] In an embodiment of the switching device, an output of the coil power supply monitoring circuit is coupled or connected to the input side of the failure diagnostic circuit . The failure diagnostic circuit is configured to provide the failure signal as a function of the fast-off signal . The output of the coil power supply monitoring circuit is coupled or connected e . g. to an input of the coil control circuit .

[0035] In an embodiment of the switching device, the control circuit further comprises an enable input terminal, an enable driver circuit and an enable input monitoring circuit . An input of the enable driver circuit is coupled or connected to the enable input terminal . The enable input monitoring circuit comprises inputs coupled or connected to the enable input terminal and to an output of the enable driver circuit . The enable input monitoring circuit is configured to provide an enable monitoring signal .

[0036] In an embodiment of the switching device, the control circuit further comprises the power supply circuit having an output coupled or connected to the supply input of the coil control circuit . The enable driver circuit comprises a control output coupled or connected to a control input of the power supplyP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0037] circuit . The enable driver circuit provides a control signal to the power supply circuit to set the power supply circuit in an active state or an inactive state . The control output of the enable driver circuit is identical or different from the output of the enable driver circuit that is coupled or connected to the enable input monitoring circuit .

[0038] In an embodiment of the switching device, an output of the enable input monitoring circuit is coupled or connected to the input side of the failure diagnostic circuit . The failure diagnostic circuit is configured to provide the failure signal as a function of the enable monitoring signal . The output of the enable input monitoring circuit is coupled or connected e . g. to an input of the coil control circuit .

[0039] In an embodiment of the switching device, the control circuit comprises at least one circuit or at least two circuits or at least three circuits or all four circuits of a group consisting of the current measurement monitoring circuit, the enable input monitoring circuit, the coil de-energizing monitoring circuit and the coil power supply monitoring circuit .

[0040] In an embodiment, the switching device is implemented as one of a group consisting of a circuit breaker, a contactor, a switch disconnector and a combination of a circuit breaker and a contactor . A combination of a circuit breaker and a contactor can be named e . g. breaktor .

[0041] In an embodiment, the switching device is free of a microcontroller or microprocessor . The switching device does not operate using a software . The switching device is free of a code .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0042] In an embodiment, an arrangement comprises the switching device and a battery management circuit . The battery management circuit can be named battery management system, abbreviated BMS . The arrangement further comprises e . g. a battery and an electric motor . The switching device is arranged e . g. between the battery and the electric motor . The arrangement may be named system. In an example, an electric vehicle comprises the arrangement .

[0043] In an embodiment, a method for monitoring a switching device which comprises a main switch, a coil coupled to the main switch, and a control circuit with a coil control circuit coupled to the coil comprises the following steps :

[0044] generating a state signal as a function of a state of the main switch by a state diagnostic circuit, and generating a failure signal as a function of a failure detected in and / or by the control circuit by a failure diagnostic circuit .

[0045] Advantageously, the state of the main switch and failures of circuits inside the control circuit are monitored.

[0046] For example, the failure diagnostic circuit provides the failure signal as a function of at least one signal, of at least two signals, of at least three signals or of the four signals of a group consisting of a current sensor monitoring signal, an enable monitoring signal, a coil monitoring signal and a fast-off signal .

[0047] In an embodiment, the coil control circuit provides electrical power to the coil . For example, the coil control circuit provides a voltage or a coil current to the coil .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0048] The switching device and the arrangement are particularly suitable for the method for monitoring a switching device . Features described in connection with the switching device or the arrangement can therefore be used for the method and vice versa .

[0049] In an example, the switching device is implemented by an ISO 26262 ASIL C compliant safety architecture . In an example, the switching device is realized as a combination of a circuit breaker and a connector, shorted breaktor . Thus, the switching device uses a safety architecture which is safety compliant for ASIL C level with respect to ISO 26262 : 2018 standard .

[0050] In an example, the switching device is utilized in an electric vehicle and is interfaced with a high-level control unit (abbreviated HLCU) . The switching device is used to break the connection between a high voltage battery (abbreviated HV battery) and a battery electric arrangement . The switching device replaces e . g. traditional fuses and contactors . The switching device is independent of the current direction allowing application for both charging and duty use .

[0051] In an example, in order to achieve safe state in case of HV battery over current or short circuit condition in electric vehicles application or failure in the HLCU or switching device failure, the switching device incorporates a safety architecture . The safety architecture is used for detection of over current or open high-voltage contacts event (e . g. via enable signal input or via s supply voltage) . The switching device discharges the coil to open main high-voltage contactsP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0052] (abbreviated HV contacts) on high voltage bus line (abbreviated HV bus line) . This will disconnect the HV battery from the HV bus line . In addition, the HLCU can also open / close the contactor of the switching device on HV bus line on receipt of a control command (via an enable input terminal) in normal operation. The main HV contacts state is reported by a state signal and failure of safety related electronic components internal of the switching device is reported by a failure signal to the HLCU. The HLCU can take safe state of opening the HV-Contacts based upon the state signal and the failure signal .

[0053] In an example, the safety architecture provides at least one of the following safety features :

[0054] - Short circuit protection and predetermined level for over current threshold that open HV-contacts .

[0055] - Open HV-contacts via an enable input or via a power supply that discharges the coil to open main HV contacts on the HV bus line .

[0056] - HLCU can also open / close the contactor of the switching device on HV bus line on receipt of a control command (via the enable input terminal) in normal operation. The control logic is developed with hardware components and does not use any software component .

[0057] - The main HV-contacts state is reported at the state signal . HLCU can take safe state based upon the feedback provided by the state signal .

[0058] - An internal safety critical failure is reported by the failure signal to the HLCU. HLCU can take safe state based upon the feedback provided by the failure signal . In case a fault is present in the switching device, the HLCU is able to take necessary action to bring the arrangement into safe state .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0059] In an example, the safety architecture provides features such as e . g. enable input monitoring and validation, coil power supply monitoring, current measurement monitoring and / or monitoring of fast de-energizing circuit .

[0060] In an example, the architecture is designed to meet the ASIL C rating with over current monitoring circuit and hardware logic block - without micro-processor or micro-controller . The control logic is developed with hardware component and does not use any software component; thus, product cost and software overheads are reduced. The architecture is capable to invoke the safe state in case of required demand of the HLCU, a fault in the HLCU (e . g. fault in enable input, a loss of power to the switching device) or a malfunction of the switching device (internal failure) . The architecture is capable to monitor over current and short circuit current and take safe reaction by a safe opening of the HV-contacts . In case of failure of safety related electronics components internal to switching device, the architecture is capable to detect that and report to the HLCU by the failure signal; the HLCU can take necessary action based on that .

[0061] In an example, an advantage of the switching device is e . g. as following:

[0062] - Irrespective of faults either in HLCU or fault in power supply to the switching device or malfunction of the arrangement or internal faults of the arrangement, the arrangement achieves safe state with the help of the safety architecture described above and below.

[0063] - This safety architecture improves the vehicle reliability and safety in terms of safe shut down of the arrangement in case of short circuit or over current event or in case ofP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0064] - 12 -

[0065] failure in the above mentioned arrangement with the switching device .

[0066] BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The following description of figures of examples or embodiments may further illustrate and explain aspects of the switching device and the method for monitoring a switching device . Arrangements, devices and circuit blocks with the same structure and the same effect, respectively, appear with equivalent reference symbols . As far as arrangements, devices and circuit blocks correspond to one another in terms of their function in different figures, the description thereof is not repeated for each of the following figures .

[0068] Figure 1 shows an exemplary embodiment of an arrangement with a switching device; and

[0069] Figures 2A to 2E show exemplary embodiments of details of a switching device .

[0070] Figure 1 shows an exemplary embodiment of an arrangement 80 with a switching device 10. The arrangement 80 comprises the switching device 10 and a battery management circuit 81, abbreviated e . g. BMS . The switching device 10 comprises a main switch 11, a coil 12 coupled to the main switch 11, and a control circuit 13 with a coil control circuit 14. The coil control circuit 14 is coupled or connected to the coil 12. Furthermore, the switching device 10 comprises a state diagnostic circuit 15 with an input coupled to the main switch 11. The switching device 10 comprises a failure diagnostic circuit 16 with an input side coupled to the control circuit 13. The switching device 10 is connected toP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0071] the battery management circuit 81. The coil 12 is an actuator coil .

[0072] The control circuit 13 comprises optionally a current measurement monitoring circuit 33 which generates a current sensor monitoring signal DOFF.

[0073] The control circuit 13 comprises optionally an enable input monitoring circuit 47 which generates an enable monitoring signal SEM.

[0074] The control circuit 13 comprises optionally a coil deenergizing monitoring circuit 35 which generates a coil monitoring signal DK.

[0075] The control circuit 13 comprises optionally a coil power supply monitoring circuit 41 which generates a fast-off signal FOFF.

[0076] The coil control circuit 14 comprises e . g. a logic circuit to combine the signals received by the coil control circuit 14. The coil control circuit 14 comprises e . g. a power supply circuit 40 (as shown in Figures 2D and 2E) which couples an output of the logic circuit to an output of the coil control circuit 14. The coil control circuit 14 provides e . g. a coil current ICL to the coil 12.

[0077] The state diagnostic circuit 15 provides a state signal DIA1 as a function of a state of the main switch 11. The state signal DIA1 can be named state diagnostic signal . The failure diagnostic circuit 16 provides a failure signal DIA2 as a function of a failure detected in the control circuit 13. The failure signal DIA2 can be named failure diagnostic signal .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0078] The control circuit 13 comprises at least one circuit or at least two circuits or at least three circuits or all four circuits of a group consisting of the current measurement monitoring circuit 33, the enable input monitoring circuit 47, the coil de-energizing monitoring circuit 35 and the coil power supply monitoring circuit 41. Thus, the failure diagnostic circuit 16 provides the failure signal DIA2 as a function of at least one signal, of at least two signals, of at least three signals or of the four signals of a group consisting of the current sensor monitoring signal DOFF, the enable monitoring signal SEM, the coil monitoring signal DK and the fast-off signal FOFF.

[0079] The switching device 10 has a low voltage interface 17 with the BMS 81. The low voltage interface 17 comprises e . g. the following pins : At pin 1, the state signal DIA1 - showing the diagnosis of the switching state using a mirror contact - is provided to the BMS 81. At pin 2, the failure signal DIA2 -showing the diagnosis internal state - is provided to the BMS 81. At pin3, a power supply is provided to the switching device 10. At pin4, a diagnosis supply is provided to the switching device 10. At pin5, a reference potential GND for the signals and the supply is provided to the switching device 10. At pin6, an enable signal EN is provided to the switching device 10. Pin 3 to pin 6 are not shown in Figure 1 .

[0080] Figure 2A shows an exemplary embodiments of details of a switching device 10 which is a further development of the embodiment shown in Figure 1. The switching device 10 further comprises a mirror switch 20 which is mechanically connectedP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0081] to the main switch 11. The mirror switch 20 changes its state in case the main switch 11 changes its state .

[0082] The main switch 11 comprises a first and a second fixed contact 21, 22, a contact bridge 23, and a first and a second movable contact 24, 25 which are arranged at the contact bridge 23. The main switch 11 comprises an armature 26, indicated by a dashed line . The armature 26 is coupled to the coil 12 and to the contact bridge 23. The coil 12 is realized as magnetic drive . The coil 12 provides a force on the armature 26. The force results in a movement of the armature 26. The armature 26 directly or indirectly moves the contact bridge 23. Thus, the coil 12 is coupled to the main switch 11 .

[0083] The mirror switch 20 has a contact bridge that is mechanically linked with the contact bridge 23 of the main switch 11. In Figure 2A, the mirror switch 20 is in a conducting position, while the main switch 11 is in a nonconducting position. After a movement of the armature 26, the mirror switch 20 is in a non-conducting position, while the main switch 11 is in a conducting position. In case the mirror switch 20 and the main switch 11 are both in a conducting position, the switching device 10 has a failure . The failure may result from melting of the first movable contact 24 and of the first fixed contact 21 (or of the second movable contact 25 and of the second fixed contact 22 ) such that the contact pair cannot be opened any more .

[0084] The state diagnostic circuit 15 provides the state signal DIA1 with a first value in case the mirror switch 20 is in a conducting position and with a second value in case the mirror switch 20 is in a non-conducting position.P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0085] - 16 -

[0086] In an alternative not-shown embodiment, the mirror switch 20 and the main switch 11 are both in a conducting position at one point of time and the mirror switch 20 and the main switch 11 are both in a non-conducting position at another point of time .

[0087] Figures 2B shows an exemplary embodiment of details of a switching device 10 which is a further development of the embodiments shown in Figures 1 and 2A. The control circuit 13 further comprises a first current sensor 31 and the current measurement monitoring circuit 33 with an input coupled to the first current sensor 31. The first current sensor 31 is coupled to the coil control circuit 14. The control circuit 13 further comprises a second current sensor 32 coupled to a further input of the current measurement monitoring circuit 33. The first current sensor 31 and the second current sensor 32 are serially connected to the main switch 11. An output of the current measurement monitoring circuit 33 is coupled to an input of the failure diagnostic circuit 16.

[0088] The first current sensor 31 provides a first current signal SCI by detecting a load current IL that flows through the main switch 11. The second current sensor 32 provides a second current signal SC2 by measuring the load current IL . The current measurement monitoring circuit 33 generates a current sensor monitoring signal DOFF as a function of the first current signal SCI and of the second current signal SC2 . The failure diagnostic circuit 16 provides the failure signal DIA2 as a function of the current sensor monitoring signal DOFF.P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0089] - 17 -

[0090] The coil control circuit 14 compares a value of the second current signal SC2 with a reference value to detect a short circuit . In case of a short circuit, the coil control circuit 14 sets the main switch 11 in a non-conductive state .

[0091] The current measurement monitoring circuit 33 detects a failure in the first and the second the current sensors 31, 32. The current measurement monitoring circuit 33 generates the current sensor monitoring signal DOFF with a first value in case the first current signal SCI and the second current signal SC2 show a deviation of the value of the coil current IL and with a second value in case the first current signal SCI and the second current signal SC2 show identical or approximately identical values of the coil current IL. The first and the second current sensors 31, 32 are realized identically or non-identically . The first and the second current sensors 31, 32 are implemented e . g. as Hall sensors .

[0092] Figures 2C shows an exemplary embodiment of details of a switching device 10 which is a further development of the embodiments shown in Figures 1, 2A and 2B . The control circuit 10 further comprises the coil de-energizing monitoring circuit 35 which comprises an input coupled to the coil 12. The coil 12 has a first coil terminal 36 and a second coil terminal 37. For example, the input of the coil de-energizing monitoring circuit 35 is coupled or connected to the first coil terminal 36. The second coil terminal 37 is connected or coupled to a reference potential terminal 39. The coil de-energizing monitoring circuit 35 comprises e . g. a comparator or a Schmitt trigger circuit .

[0093] An output of the coil de-energizing monitoring circuit 35 is coupled to the input side of the failure diagnostic circuitP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0094] 16. The output of the coil de-energizing monitoring circuit 35 is coupled e . g. to an input of the coil control circuit 14 .

[0095] The coil de-energizing monitoring circuit 35 provides the coil monitoring signal DK as a function of a voltage or a current provided at the coil 12. For example, a voltage UFW is tapped at the first coil terminal 36 and is provided to the coil de-energizing monitoring circuit 35. The failure diagnostic circuit 16 provides the failure signal DIA2 as a function of the coil monitoring signal DK.

[0096] Figures 2D shows an exemplary embodiments of details of a switching device 10 which is a further development of the embodiments shown in Figures 1, 2A, 2B and 20. The control circuit 13 further comprises the power supply circuit 40 with an output coupled to a supply input of the coil control circuit 14. The control circuit 13 further comprises the coil power supply monitoring circuit 41 coupled to the output of the power supply circuit 40 or to the supply input of the coil control circuit 14. An output of the coil power supply monitoring circuit 41 is coupled to the input side of the failure diagnostic circuit 16. The coil power supply monitoring circuit 41 is optionally coupled to an input of the coil control circuit 14.

[0097] The power supply circuit 40 provides a supply voltage VDD to the supply input of the coil control circuit 14 and to the coil power supply monitoring circuit 41. The coil power supply monitoring circuit 41 provides the fast-off signal FOFF as a function of the supply voltage VDD. The fast-off signal FOFF is applied to the failure diagnostic circuit 16.P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0098] - 19 -

[0099] The failure diagnostic circuit 16 provides the failure signal DIA2 as a function of the fast-off signal FOFF.

[0100] The coil power supply monitoring circuit 41 comprises e . g. a comparator or a Schmitt trigger and provides the fast-off signal FOFF with a first value in case the supply voltage VDD is below a voltage value and with a second value in case the supply voltage VDD is above or equal the voltage value .

[0101] Figures 2E shows an exemplary embodiment of details of a switching device 10 which is a further development of the embodiments shown in Figures 1, 2A, 2B, 20 and 2D. The control circuit 13 further comprises an enable input terminal 45 and an enable driver circuit 46 with an input coupled to the enable input terminal 45. The enable input terminal 45 can be realized as enable pin. Additionally, the control circuit 13 further comprises the enable input monitoring circuit 47 having an input coupled to the enable input terminal 45 and a further input coupled to an output of the enable driver circuit 46. An output of the enable input monitoring circuit 47 is coupled to the input side of the failure diagnostic circuit 16. Optionally, the output of the enable input monitoring circuit 47 is coupled to an input of the coil control circuit 14.

[0102] The enable signal EN is applied to the enable input terminal 45. The enable signal EN is applied to the input of the enable driver circuit 46 and to the input of the enable input monitoring circuit 47. The enable input monitoring circuit 47 provides an enable monitoring signal SEM as a function of the enable signal EN and of a control signal SC at the output of the enable driver circuit 46. The failure diagnostic circuitP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0103] 16 provides the failure signal DIA2 as a function of the enable monitoring signal SEM.

[0104] In an example, the control circuit 13 comprises the power supply circuit 40 having an output coupled to the supply input of the coil control circuit 14. The output of the enable driver circuit 46 or a further output of the enable driver circuit 46 is coupled to a control input of the power supply circuit 40. The enable driver circuit 46 comprises e . g. at least one of an inverter, a buffer or a level shifter . The enable driver circuit 46 provides the control signal SC to the power supply circuit 40 to set the power supply circuit 40 in an active state or an inactive state .

[0105] The switching device 10 achieves product safety compliance of HV circuit protection device in EV applications . Thus, an electromechanical switchgear (e . g. comprising the switching device 10 which implements a contactor) is driven by safety related monitoring. The contactor as described above offers fail-safe behavior (i . e . taking arrangement to safe state) when the contactor fails to open HV contacts during HV battery over-current or short-circuit condition or if there is a failure in the low voltage interface 17 to the BMS 81 (BMS is the abbreviation for battery management circuit) or if there is a failure in the contactor itself . The switching device 10 comprises the above described safety architecture in order to definitely achieve safe state (i . e . open HV contact) in these failure conditions .

[0106] For example, a safety requirement (safety goal) is that the switching device 10 shall open the HV contact if requested by the BMS 81.P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0107] Comparison with a contactor without safety architecture : Such a contactor can open the HV contact with command input from the BMS 81, but a fail-safe mechanism is not available within the contactor .

[0108] The above described switching device 10 has the following safety mechanism (abbreviated SM) to comply the safety requirements in case of failure : If the switching device 10 fails to open HV contact using command from the BMS 81 due to an internal failure of the switching device 10, then the BMS 81 can detect the HV contact status on the state signal DIA1 of the switching device 10 and removes coil power of the switching device 10 to open the HV contact .

[0109] Another safety requirement (safety goal) is e . g. that the switching device 10 shall open if a short circuit is detected .

[0110] A contactor without safety architecture can detect a short circuit current and open the HV contact, but a fail-safe mechanism is not available within such a contactor .

[0111] The above described switching device 10 has the following safety mechanism to comply the safety requirements in case of failure : The switching device 10 monitors and detects an internal failure related to the first current sensor 31 such as drift, open / short circuit, also circuit that open / close HV contact, and failure related to command input . In case of a failure of a safety related electronic component internal to the switching device 10, the architecture is capable to detect this and to report to the BMS 81 over the failure signal DIA2 ; the BMS 81 can achieve a safe state by opening the HV contact using command or power .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0112] - 22 -

[0113] A further safety requirement (safety goal) is e . g. that the switching device 10 shall provide status of the HV contact (open / close) .

[0114] At a contactor without safety architecture, a HV contact status is not available within the contactor .

[0115] The above described switching device 10 has the following safety mechanism (SM) to comply the safety requirements in case of failure : If the HV contact status detected as the state signal DIA1 does not match with a command received by the switching device 10 from the BMS 81, then the BMS 81 can remove coil power to open the HV contact . The architecture is capable to invoke the safe state (i . e . open HV contact) , if the BMS 81 demands this, if there is a fault in the BMS 81 (e . g. fault in enable input or loss of power to the switching device 10) or if there is a malfunction (internal failure) of the switching device 10.

[0116] The HV contact state is reported at a feedback output providing the state signal DIA1 . The failure of safety related electronic components internal to the switching device 10 are reported at a feedback output providing the failure signal DIA2 to the BMS 81. The BMS 81 can take safe state of opening the HV contact based upon the state signal DIA1 and / or the failure signal DIA2 either by an enable command or by removing the coil power supply.

[0117] Advantageously, the safety architecture improves reliability and safety of a vehicle by invoking the safe state in case of required demand from the BMS 81, fault in the BMS 81 (e . g. fault in low voltage interface 17, e . g. command or powerP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0118] 23

[0119] supply) or malfunction of the switching device 10 (internal safety related electronics failure) . The architecture is designed to meet the ISO 26262 ASIL C rating with control logic blocks using hardware components - without micro-processor or micro-controller - and does not use any software component . Thus, product cost and software overheads are reduced and there is no need to implement ISO 26262-part 6 standard .

[0120] The invention is not limited to the description of the embodiments . Rather, the invention comprises each new feature as well as each combination of features, particularly each combination of features of the claims, even if the feature or the combination of features itself is not explicitly given in the claims or embodiments .P2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0121] - 24 -

[0122] Reference numerals

[0123] 10 switching device

[0124] 11 main switch

[0125] 12 coil

[0126] 13 control circuit

[0127] 14 coil control circuit

[0128] 15 state diagnostic circuit

[0129] 16 failure diagnostic circuit

[0130] 17 low voltage interface

[0131] 20 mirror switch

[0132] 21, 22 fixed contact

[0133] 23 contact bridge

[0134] 24, 25 movable contact

[0135] 26 armature

[0136] 31 first current sensor

[0137] 32 second current sensor

[0138] 33 current measurement monitoring circuit 35 coil de-energizing monitoring circuit 36, 37 coil terminal

[0139] 39 reference potential terminal

[0140] 40 power supply circuit

[0141] 41 coil power supply monitoring circuit 45 enable input terminal

[0142] 46 enable driver circuit

[0143] 47 enable input monitoring circuit

[0144] 80 arrangement

[0145] 81 battery management circuit

[0146] DIA1 state signal

[0147] DIA2 failure signal

[0148] DK coil monitoring signal

[0149] DOFF current sensor monitoring signal EN enable signalP2024, 1205 WO N / P24-1727WO01 February 6, 2026

[0150] - 25 -

[0151] FOFF fast-off signal

[0152] ICL coil current

[0153] IL load current

[0154] SCI first current signal SC2 second current signal SEM enable monitoring signal UFW voltage

[0155] VDD supply voltage

Claims

P2024 , 1205 WO N / P24- 1727WO01 February 6 , 2026- 26 -Claims1 . A switching device ( 10 ) , comprisinga main switch ( 11 ) ,a coil ( 12 ) coupled to the main switch ( 11 ) ,a control circuit ( 13 ) with a coil control circuit ( 14 ) coupled to the coil ( 12 ) ,a state diagnostic circuit ( 15 ) with an input coupled to the main switch ( 11 ) , anda failure diagnostic circuit ( 16 ) with an input side coupled to the control circuit ( 13 ) .2 . The switching device ( 10 ) of claim 1 ,wherein the state diagnostic circuit ( 15 ) is configured to provide a state signal ( DIA1 ) as a function of a state of the main switch ( 11 ) .3 . The switching device ( 10 ) of claim 1 or 2 ,wherein the switching device ( 10 ) further comprises a mirror switch ( 20 ) which is mechanically connected to the main switch ( 11 ) and is configured to change its state in case the main switch ( 11 ) changes its state ,wherein the state diagnostic circuit ( 15 ) is coupled to the mirror switch ( 20 ) and is configured to provide the state signal ( DIA1 ) with a first value in case the mirror switch ( 20 ) is in a conducting position and with a second value in case the mirror switch ( 20 ) is in a non-conducting position .4 . The switching device ( 10 ) of one of claims 1 to 3 , wherein the failure diagnostic circuit ( 16 ) is configured to provide a failure signal ( DIA2 ) as a function of a failure detected in the control circuit ( 13 ) .P2024, 1205 WO N / P24-1727WO01 February 6, 2026- 27 -5. The switching device ( 10) of one of claims 1 to 4, wherein the control circuit ( 13) further comprisesa first current sensor (31 ) coupled to an input of the coil control circuit ( 14 ) and configured for providing a first current signal (SCI ) by measuring a load current ( IL) that flows through the main switch ( 11 ) , anda current measurement monitoring circuit (33) with an input coupled to the first current sensor (31 ) ,wherein the current measurement monitoring circuit (33) is configured to generate a current sensor monitoring signal (DOFF) as a function of at least the first current signal (SCI ) .

6. The switching device ( 10) of claim 5,wherein the control circuit ( 13) further comprises a second current sensor (32 ) configured for providing a second current signal (SC2 ) by measuring the load current ( IL) that flows through the main switch ( 11 ) , andwherein the current measurement monitoring circuit (33) is additionally coupled to the second current sensor (32) and is configured to generate the current sensor monitoring signal (DOFF) as a function of the first current signal (SCI) and of the second current signal (SC2 ) .

7. The switching device ( 10) of claim 5 or 6,wherein an output of the current measurement monitoring circuit (33) is coupled to the input side of the failure diagnostic circuit ( 16) , andwherein the failure diagnostic circuit ( 16) is configured to provide the failure signal (DIA2 ) as a function of the current sensor monitoring signal (DOFF) .

8. The switching device ( 10) of one of claims 1 to 7,P2024, 1205 WO N / P24-1727WO01 February 6, 2026- 28 -wherein the control circuit ( 13) further comprises a coil deenergizing monitoring circuit (35) which comprises an input coupled to the coil ( 12 ) , andwherein the coil de-energizing monitoring circuit (35) is configured to provide a coil monitoring signal (DK) as a function of a voltage or a current provided at the coil ( 12 ) .

9. The switching device ( 10) of claim 8,wherein an output of the coil de-energizing monitoring circuit (35) is coupled to the input side of the failure diagnostic circuit ( 16) , andwherein the failure diagnostic circuit ( 16) is configured to provide the failure signal (DIA2 ) as a function of the coil monitoring signal (DK) .

10. The switching device ( 10) of one of claims 1 to 9, wherein the control circuit ( 13) further comprisesa power supply circuit (40) with an output coupled to a supply input of the coil control circuit ( 14 ) and configured to provide a supply voltage (VDD) anda coil power supply monitoring circuit (41 ) coupled to the power supply circuit (40) and configured to provide a fast-off signal (FOFF) as a function of the supply voltage (VDD) .

11. The switching device ( 10) of claim 10,wherein an output of the coil power supply monitoring circuit (41 ) is coupled to the input side of the failure diagnostic circuit ( 16) , andwherein the failure diagnostic circuit ( 16) is configured to provide the failure signal (DIA2 ) as a function of the fast-off signal (FOFF) .P2024 , 1205 WO N / P24- 1727WO01 February 6 , 2026- 29 -12 . The switching device ( 10 ) of one of claims 1 to 11 , wherein the control circuit ( 13 ) further comprisesan enable input terminal ( 45 ) ,an enable driver circuit ( 46 ) with an input coupled to the enable input terminal ( 45 ) , andan enable input monitoring circuit ( 47 ) having inputs coupled to the enable input terminal ( 45 ) and to an output of the enable driver circuit ( 46 ) ,wherein the enable input monitoring circuit ( 47 ) is configured to provide an enable monitoring signal ( SEM) .13 . The switching device ( 10 ) of claim 12 ,wherein an output of the enable input monitoring circuit ( 47 ) is coupled to the input side of the failure diagnostic circuit ( 14 ) , andwherein the failure diagnostic circuit ( 16 ) is configured to provide the failure signal ( DIA2 ) as a function of the enable monitoring signal ( SEM) .14 . The switching device ( 10 ) of one of claims 1 to 13 , wherein the switching device ( 10 ) is implemented as one of a group consisting of a circuit breaker, a contactor, a switch disconnector and a combination of a circuit breaker and a contactor .15 . A method for monitoring a switching device ( 10 ) , wherein the switching device ( 10 ) comprises a main switch ( 11 ) , a coil ( 12 ) coupled to the main switch ( 11 ) , and a control circuit ( 13 ) with a coil control circuit ( 14 ) coupled to the coil ( 12 ) ,wherein the method comprisesP2024 , 1205 WO N / P24- 1727WO01 February 6 , 2026generating a state signal ( DIA1 ) as a function of a state of the main switch ( 11 ) by a state diagnostic circuit ( 15 ) , andgenerating a failure signal ( DIA2 ) as a function of a failure detected in the control circuit ( 13 ) by a failure diagnostic circuit ( 16 ) .

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