Method and device for releasing a switching contact of a mechanical high-voltage switch

Abstract

The invention relates to a method for releasing a switching contact (18) of a mechanical high-voltage switch (10), comprising a mechanical high-voltage switch (10) having a housing (12) and a mechanical vibration device (22) which is arranged externally on the housing (12) of the high-voltage switch (10), wherein a switching state of the mechanical high-voltage switch (10) is monitored, wherein a vibration protocol is activated and the mechanical vibration device (22) is controlled according to the vibration protocol when an operating state of the mechanical high-voltage switch (10) with a high risk of sticking or a stuck switching contact (18) of the mechanical high-voltage switch (10) is detected, wherein vibrations generated by the mechanical vibration device (22) are transmitted from the outside via a housing (12) of the mechanical high-voltage switch (10) to the switching contact (18).wherein at the end of the vibration protocol a check of the switching state of the mechanical high-voltage switch (10) is carried out, as well as a device (20) for carrying out such a method for releasing a switching contact (18) of a mechanical high-voltage switch (10).

Description

[0001] The invention relates to a method for releasing a switching contact of a mechanical high-voltage switch. Furthermore, the invention relates to a device for carrying out such a method for releasing a switching contact of a mechanical high-voltage switch.

[0002] Methods for releasing a switching contact of a mechanical high-voltage switch are known in numerous variations.

[0003] Such a mechanical high-voltage switch can be used, for example, in electrically powered vehicles to connect the traction battery to the electric drive. Two mechanical high-voltage switches can be used, for instance, to create a closed circuit as soon as the high-voltage system is activated and to open the circuit again as soon as the high-voltage system is to be de-energized. Preferably, the mechanical high-voltage switches are each designed as high-voltage relays with a movable switching contact, which can also be referred to as a contactor. In some situations, the mechanical high-voltage switch may need to be opened under load, meaning that current continues to flow during the opening process. In electric vehicles, these currents can reach several hundred amperes, depending on the vehicle's operating state (e.g., charging, charging, or discharging).(when the battery is being charged or the vehicle is accelerating or decelerating). Opening the mechanical high-voltage switch under load can cause the moving switch contact to fuse and stick with the fixed working contacts of the mechanical high-voltage switch. This means that the mechanical high-voltage switch no longer opens, or only opens partially. This mechanical fault can make it impossible to continue driving, and the mechanical high-voltage switch must be replaced.

[0004] From DE 10 2015 016 992 B4, a method for cleaning electrical contacts of an electrical switching device is known. In this method, at least one electrical contact is cleaned, which has at least one first contact element and at least one second contact element. The contact elements can be moved relative to each other into an open position and a closed position. The first contact element and the second contact element are arranged in the closed position and excited to mechanical vibrations relative to each other by applying an electrical waveform to the electrical contact in the closed position. During operation of the switching device, the electrical waveform is superimposed on an electric current.

[0005] From EP 0 294 794 B1, a circuit arrangement for releasing the contacts of a stuck relay is known. One contact of the relay is stationary, while the other contact is located on the ferromagnetic relay armature. When an electrical voltage is applied to the winding of the relay coil, the stationary contact is attracted to the stationary contact. When the relay coil is de-energized, and the relay is functioning correctly, the stationary contact de-energizes, thus separating the two contacts. In this circuit arrangement, a sticking of the relay contacts is detected by a comparator circuit. This comparator circuit is controlled at one input by the relay's control signal and at the other input by the load circuit to be switched by the relay. The circuit compares the waveform of the load signal to be switched by the relay with the waveform of the relay's control signal.In this case, the output signal of the comparator circuit controls a switching device, which, in the event of stuck relay contacts, applies the output signal of a generator producing an alternating voltage or a pulsating direct voltage to the relay winding or to the control input of a relay driver that switches the electric current through the relay winding, instead of the control signal of the relay.

[0006] From WO 2023 / 180582 A1, a power circuit for increasing the release force when switching a mechanical relay in a charger or charging cable for a motor vehicle is known. The relay comprises a spring-loaded armature for establishing or breaking an electrical connection in a primary circuit for charging the motor vehicle. The armature is moved by a control unit via an excitation coil. The relay's control unit is configured to apply a periodic excitation voltage with an excitation frequency corresponding to the natural frequency of the spring-mass system of the relay armature, synchronously with the switching voltage of the excitation coil for breaking the electrical connection. This excitation voltage causes the armature to vibrate, and the resulting dynamic force releases the armature from the contact if it has become stuck due to welding during operation.

[0007] DE 10 2012 011 251 A1 discloses a device with an electromechanical relay in an electrical load circuit and an electrical control circuit, wherein the relay has a contact bridge that can be moved electromechanically against the force of a return spring, wherein a detection device detects a relay malfunction with a “sticky” contact bridge and, as a countermeasure, the electrical control circuit is then activated with successive pulses for a corresponding “shaking free” of the contact bridge until it is released and reset with the opening of the load circuit.

[0008] DE 10 2012 207 592 A1 discloses a circuit arrangement comprising a relay and at least one control unit for controlling the relay, wherein feedback is provided to the control unit via a feedback contact on the output line of the relay, by means of which the switching state of the relay can be determined. The control unit is configured such that, upon detection of a contact interruption with the relay closed, the relay is actuated by the control unit once or several times.

[0009] The invention is based on the objective of providing a method for releasing a switching contact of a mechanical high-voltage switch and a device for carrying out such a method for releasing a switching contact of a mechanical high-voltage switch, which prevents a movable switching contact of the mechanical high-voltage switch from sticking or releases an existing sticking of the movable switching contact.

[0010] This problem is solved by a method for releasing a switching contact of a mechanical high-voltage switch with the features of claim 1 and by a device for releasing a switching contact of a mechanical high-voltage switch with the features of claim 9. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0011] To provide a method for releasing a switching contact of a mechanical high-voltage switch, preventing or releasing a stuck moving contact, the switching state of the mechanical high-voltage switch is monitored. A vibration protocol is activated, and a mechanical vibration device is controlled according to this protocol when a high-risk operating state of the mechanical high-voltage switch or a stuck switching contact is detected. Vibrations generated by the mechanical vibration device are transmitted externally to the switching contact via the housing of the mechanical high-voltage switch. At the end of the vibration protocol, the switching state of the mechanical high-voltage switch is also checked.

[0012] Furthermore, a device is proposed comprising a mechanical vibration device and an evaluation and control unit, designed to perform a method for releasing a switching contact of a mechanical high-voltage switch. The mechanical vibration device is arranged externally on the housing of the mechanical high-voltage switch and is designed to generate vibrations and transmit them from the outside via the housing to the switching contact. The evaluation and control unit is designed to control the mechanical vibration device with at least one control signal having a predetermined frequency, amplitude, and duration when an operating condition of the mechanical high-voltage switch with a high risk of sticking or a stuck switching contact is detected.

[0013] Embodiments of the invention combine proactive vibration excitation to prevent adhesion or welding with a reactive approach to break existing adhesion or welding. Proactive excitation of the mechanical vibration device minimizes arc residue and adhesive forces by providing targeted vibration assistance when opening the mechanical high-voltage switch, before adhesion or welding can occur. Reactive excitation of the mechanical vibration device breaks existing adhesion or welding, for example, through a multi-stage vibration protocol. This protocol can cycle through several intensities, which can be progressively increased to break even stubborn adhesion or welding.Furthermore, the mechanical vibration device can be mechanically coupled to the housing in such a way that the generated vibrations act selectively on the contacts of the mechanical high-voltage switch without stressing adjacent components. Preferably, the mechanical vibration device can be attached to the housing of the mechanical high-voltage switch by means of screw or clamping mechanisms. This positioning enables effective transmission of the vibrations to the attached or welded contacts.

[0014] Embodiments of the invention can preferably be used for mechanical high-voltage switches in electrically powered vehicles. Such a mechanical high-voltage switch is a safety-critical component that must reliably switch high-voltage currents. Adhesions or welds occur primarily in the event of a fault, when the mechanical high-voltage switch is opened under load. The term "mechanical high-voltage switch" is understood below to mean an electrical switch comprising a movable switching contact, two fixed working contacts, and an electromagnet, and suitable for carrying a high current load of up to several hundred amperes to establish a closed circuit in the high-voltage system of a vehicle. Preferably, the mechanical high-voltage switch can be designed as a high-voltage relay, which can also be referred to as a contactor. In this case, the movable switching contact is held in an open position by a return spring.When the electromagnet generates an electromagnetic field, the switching contact moves into an operating position, establishing an electrical connection between the two working contacts, thus creating a closed circuit. Current can flow until the electromagnet itself is de-energized and the magnetic field is dissipated. The return spring then moves the switching contact back to its open position.

[0015] Embodiments of the invention enable increased reliability, as the risk of failure of the mechanical high-voltage switches and thus of the corresponding high-voltage battery assembly can be significantly reduced. Furthermore, the ability to release stuck or welded switching contacts of the mechanical high-voltage switches without having to replace them results in considerable savings in spare parts costs and labor. In addition, the service life of the mechanical high-voltage switches can be extended by preventing the repeated sticking or welding of the switching contact. The vibration protocol can be fully automated and integrated into existing vehicle control systems.

[0016] In an advantageous embodiment of the method, the contact resistance and switching times of the switching contact can be continuously monitored during the execution of the vibration protocol. This allows the success of the measure to be quickly detected and the excitation of the mechanical vibration device to be intelligently adjusted.

[0017] In a further advantageous embodiment of the method, the vibrations can be generated with a frequency, amplitude, and duration adapted to the mechanical high-voltage switch. Thus, the frequencies, amplitudes, and duration of the vibrations can be dynamically adjusted based on the operating conditions and the age of the mechanical high-voltage switch. The vibration frequencies can be preset to lie outside the resonant frequencies of the battery mounts or the vehicle structure to avoid negative effects. Furthermore, the vibrations can be generated with a frequency, amplitude, and duration adapted to the operating state or the degree of adhesion. In this way, an impending emergency shutdown of the mechanical high-voltage switch can be detected as an operating state with a high risk of adhesion. In operating states with a high risk of adhesion, or...To prevent welding failure, vibration excitation can be activated even during the opening of the mechanical high-voltage switch.

[0018] In a further advantageous embodiment of the method, the vibration protocol can be executed with vibrations at several intensity levels, which may differ in frequency, amplitude, and / or duration. Thus, in operating conditions with a high risk of adhesion or welding, the vibration protocol can reduce initial adhesion forces at the start of the opening process. In a transition phase, the vibration protocol can support complete separation of the contacts through moderate vibrations. In a final phase, the vibration protocol can ensure that the contacts remain completely separated and no residue adheres. A staged vibration protocol can also be initiated to break adhesions or welds, which can cycle through several progressively increasing intensities to break even stubborn adhesions or welds.The vibration protocol, at its first intensity level, can gently stimulate loose adhesions or welds without stressing the mechanical high-voltage switch. At its second intensity level, the protocol can overcome adhesive forces and micro-welds through increased vibration intensity. At its third intensity level, the vibration protocol can break down stubborn adhesions or welds through high-frequency vibrations with maximum amplitude.

[0019] In a further advantageous embodiment of the method, the vibration protocol can be terminated if a disconnected switching contact is detected during the switching state check. Alternatively, the vibration protocol can be repeated at least once if the switching contact remains engaged. In this case, a warning message indicating the need for manual intervention can be generated and displayed if the switching contact remains engaged after a predetermined number of vibration protocols have been performed.

[0020] In an advantageous embodiment of the device, the housing of the high-voltage switch can be mounted with vibration damping. Such vibration-isolating measures can prevent negative effects on other vehicle components. For example, rubber mounts or mounts made of other suitable vibration-damping materials can be used to prevent the transmission of vibrations.

[0021] The advantages and preferred embodiments described for the inventive method for releasing a switching contact also apply to the inventive device for carrying out the method for releasing a switching contact.

[0022] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. In the drawings, identical reference numerals denote components or elements that perform the same or analogous functions. These show: Fig. 1 a schematic flowchart of an embodiment of a method according to the invention for releasing a switching contact of a mechanical high-voltage switch; Fig. 2 a schematic representation of an embodiment of a high-voltage battery arrangement with a device according to the invention for releasing a switching contact of a mechanical high-voltage switch; Fig. 3 a schematic representation of the device according to the invention for releasing a switching contact of a mechanical high-voltage switch made of Fig. 2 with the switching contact in an open position; Fig. 4 a schematic representation of the device according to the invention for releasing a switching contact of a mechanical high-voltage switch made of Fig. 2 with the switching contact in a working position; and Fig. 5 a schematic representation of the device according to the invention for releasing a switching contact of a mechanical high-voltage switch made of Fig. 2 with the switching contact in an adherent state.

[0023] As from Fig. As can be seen in Figure 1, the illustrated embodiment of a method 100 according to the invention for releasing a switching contact 18 of a Fig. 2, Fig. 3, Fig. 4 to Fig. Figure 5 of the mechanical high-voltage switch 10 shows a step S100 in which the switching state of the mechanical high-voltage switch 10 is monitored. In step S110, a vibration protocol is activated, and in step S120, a mechanical vibration device 22 is controlled according to the vibration protocol if an operating state of the mechanical high-voltage switch 10 with a high risk of sticking or a stuck switching contact 18 of the mechanical high-voltage switch 10 is detected. In step S130, vibrations generated by the mechanical vibration device 22 are transmitted via a housing 12 of the mechanical high-voltage switch 10 to the switching contact 18. In step S140, at the end of the vibration protocol, a check of the switching state of the mechanical high-voltage switch 10 is performed.

[0024] As from Fig. As can be seen further in Figure 1, in the illustrated embodiment, the vibration protocol is terminated in step S150 if a released switching contact 18 is detected during the switching state check. If it is determined in step S140 that the switching contact 18 is still engaged, the vibration protocol is repeated at least once. In the illustrated embodiment, the number of completed vibration protocols is counted in step S160. If the number of completed vibration protocols is below a predetermined value, for example, three, the vibration protocol is repeated with modified parameters if necessary, and the method 100 continues with step S100. If the number of completed vibration protocols corresponds to the predetermined value, a warning message indicating the need for manual intervention is generated and displayed in step S170, and the method is terminated in S150.

[0025] As from Fig. 2, Fig. 3, Fig. 4 to Fig. As can be seen in Figure 5, the device 20 for carrying out the method 100 for releasing a switching contact 18 of a mechanical high-voltage switch 10 comprises a mechanical vibration device 22 and an evaluation and control unit 30. The mechanical vibration device 22 is arranged externally on a housing 12 of the mechanical high-voltage switch 10 and is designed to generate vibrations and transmit them externally via the housing 12 to the switching contact 18. The evaluation and control unit 30 is designed to control the mechanical vibration device 22 with at least one control signal having a predetermined frequency, amplitude, and duration when an operating state of the mechanical high-voltage switch 10 with a high risk of sticking or a stuck switching contact 18 is detected.

[0026] In the illustrated embodiment, the housing 12 of the high-voltage switch 10 is mounted with vibration damping. This prevents negative effects on the vehicle structure, noise generation, or sensitive sensors. Furthermore, the set vibration parameters are monitored in real time to ensure that no unwanted effects occur. In addition, the vibration amplitude is limited to a minimum sufficient to overcome the adhesive forces of the bonded or welded contacts without transmitting significant vibrations to the vehicle. If necessary, the vibrations can be automatically deactivated.

[0027] As from Fig. As can be seen further in Figure 2, the illustrated high-voltage battery arrangement 1 for a vehicle comprises a high-voltage battery 3, which can be connected to an electric motor 5 of the vehicle via two mechanical high-voltage switches 10, and a motor control unit 7, which controls the two mechanical high-voltage switches 10. In the illustrated embodiment, the mechanical high-voltage switches 10 are suitable for carrying a high current load of up to several hundred amperes in order to establish a closed circuit in the illustrated high-voltage battery arrangement 1 of the vehicle. A first high-voltage switch 10A, shown on the left, connects a positive terminal of the high-voltage battery 3 to the electric motor 5, and a second high-voltage switch 10B, shown on the right, connects a negative terminal of the high-voltage battery 3 to the electric motor 5. Each of the two mechanical high-voltage switches 10 comprises two fixed working contacts 16 and one movable switching contact 18.In this configuration, a first working contact 16A is electrically connected to the high-voltage battery 3, and a second working contact 16B is electrically connected to the electric motor 5. Each of the two mechanical high-voltage switches 10 is associated with a mechanical vibration device 22, which is arranged on a housing 12 of the respective mechanical high-voltage switch 10 and, in the illustrated embodiment, is controlled by a common evaluation and control unit 30. As shown in the figure below. Fig. As can be seen further in Figure 2, a first vibration device 22A is assigned to the first mechanical high-voltage switch 10A and a second vibration device 22B is assigned to the second mechanical high-voltage switch 10B.

[0028] As from Fig. 3, Fig. 4 to Fig. As can be seen in Figure 5, which shows a more detailed representation of the first mechanical high-voltage switch 10A with the first mechanical vibration device 22, the depicted mechanical high-voltage switch 10 comprises, in addition to the two stationary working contacts 16A, 16B and the movable switching contact 18, a return spring 19 and an electromagnet 14. As can be seen from Fig. As can be seen in Figure 3, the movable switching contact 18 is held in the open position shown by the return spring 19. If the electromagnet 14 generates an electromagnetic field, then the switching contact 18 is moved into a position shown in Figure 3. Fig. 4. The working position shown is moved, in which the switching contact 18 establishes an electrical connection between the two working contacts 16, thus creating a closed circuit. Current can flow until the electromagnet 14 itself is de-energized and the magnetic field is thus dissipated. The return spring 19 then moves the switching contact back into its position. Fig. 3 shown open position. If the mechanical high-voltage switch 10 is opened under load, this can lead to the event described in Fig. Figure 5 shows the mechanical high-voltage switch 10 in a stuck or welded state, in which the switching contact 18 adheres, for example, by a weld 9 to one or both working contacts 16. This means that the mechanical high-voltage switch 10 can no longer open fully or can only open partially. This condition can be avoided by embodiments of the invention.

[0029] In the illustrated embodiments of the invention, the contact resistance and switching times of the switching contact 18 are continuously monitored during the execution of the vibration protocol. This allows the success of the vibration protocol or the degree of adhesion to be detected.

[0030] In the illustrated embodiments, the vibrations are generated with a frequency, amplitude, and duration adapted to the mechanical high-voltage switch 10. Additionally, the frequency, amplitude, and duration of the generated vibrations are adapted to the operating condition or the degree of adhesion. An impending emergency shutdown of the mechanical high-voltage switch 10 is recognized as an operating condition with a high risk of adhesion. The vibration protocol is executed with vibrations at several intensity levels, which differ in frequency and / or amplitude and / or duration.

[0031] In the illustrated embodiments, the vibration protocol activates 10 start vibrations at the beginning of the opening of the mechanical high-voltage switch in operating conditions with a high risk of adhesion or welding. These initial vibrations operate in a low frequency range of, for example, 20 to 30 Hertz, have a low amplitude of, for example, 0.1 millimeters, and a short duration of, for example, 0.5 seconds. This reduces initial adhesion forces at the start of the opening process.

[0032] In a second intensity level, the vibration protocol activates transition vibrations, which lie in a second, higher frequency range of, for example, 40 to 60 Hertz, have a higher amplitude of, for example, 0.2 millimeters, and a longer duration of, for example, 1.0 second. This allows for complete contact separation through moderate vibrations.

[0033] In a third intensity level, the vibration protocol activates final vibrations, which operate in a third, higher frequency range of, for example, 80 to 100 Hertz, have a medium amplitude of, for example, 0.15 millimeters, and a short duration of, for example, 0.5 seconds. This ensures that the contacts remain completely disconnected and no residue adheres to them.

[0034] To loosen adhesions or welds, a staged vibration protocol is initiated, which can cycle through several progressively increasing intensities to loosen even stubborn adhesions or welds. For example, in the first stage, the vibration protocol activates low-intensity vibrations in a low frequency range of, for example, 15 to 25 Hertz, with a low amplitude of, for example, 0.1 millimeters and a short duration of, for example, 1.0 second. This allows for gentle stimulation to loosen adhesions or welds without stressing the mechanical high-voltage switch.

[0035] In a second intensity level, the vibration protocol activates, for example, medium-intensity vibrations in a higher frequency range of, for example, 50 to 70 Hertz, with a higher amplitude of, for example, 0.2 millimeters and a longer duration of, for example, 2.0 seconds. This increased vibration intensity allows for the overcoming of adhesion forces and micro-welding points.

[0036] In a third intensity level, the vibration protocol activates, for example, high-intensity vibrations in a third, higher frequency range of, for example, 90 to 150 Hertz, with an even higher amplitude of, for example, 0.3 millimeters and a duration of, for example, 2.0 seconds. This enables the removal of stubborn adhesions or welds through high-frequency vibrations with maximum amplitude. REFERENCE MARK LIST 1 High-voltage battery assembly 3 high-voltage batteries 5 electric motor 7 Engine control unit 9 Welding 10, 10A, 10B mechanical high-voltage switch 12 cases 14 Electromagnet 16, 16A, 16B fixed work contacts 18 Switching contacts 19 Return spring 20 Device for releasing switching contacts 22, 22A, 22B Vibration device 24 vibration motor 26 coupling spring 28 knocking plate 30 Evaluation and control unit S1, S2 control contact 100 methods for releasing switch contacts S100 to S170 process step

Claims

[1] Method (100) for releasing a switching contact (18) of a mechanical high-voltage switch (10), comprising a mechanical high-voltage switch (10) having a housing (12) and a mechanical vibration device (22) arranged externally on the housing (12) of the high-voltage switch (10), wherein a switching state of the mechanical high-voltage switch (10) is monitored, wherein a vibration protocol is activated and the mechanical vibration device (22) is controlled according to the vibration protocol when an operating state of the mechanical high-voltage switch (10) with a high risk of sticking or a stuck switching contact (18) of the mechanical high-voltage switch (10) is detected, wherein vibrations generated by the mechanical vibration device (22) are transmitted from the outside via the housing (12) of the mechanical high-voltage switch (10) to the switching contact (18),where, at the end of the vibration protocol, a check of the switching state of the mechanical high-voltage switch (10) is carried out. [2] Method (100) according to claim 1, characterized by , that during the execution of the vibration protocol a contact resistance and switching times of the switching contact (18) are continuously monitored. [3] Method (100) according to claim 1 or 2, characterized by , that the vibrations are generated with a frequency, amplitude and duration adapted to the mechanical high-voltage switch (10). [4] Method (100) according to any one of claims 1 to 3, characterized by that the vibrations are generated with a frequency, amplitude and duration adapted to the operating condition or to a degree of adhesion. [5] Method (100) according to any one of claims 1 to 4, characterized by , that an impending emergency shutdown of the mechanical high-voltage switch (10) is recognized as an operating condition with a high risk of adhesion. [6] Method (100) according to any one of claims 1 to 5, characterized by , that the vibration protocol is performed with vibrations at several intensity levels, which differ in frequency and / or amplitude and / or duration. [7] Method (100) according to any one of claims 1 to 6, characterized by , that the vibration protocol is terminated if a released switching contact (18) is detected during the switching state check, or that the vibration protocol is repeated at least once if the switching contact (18) remains stuck. [8] Method (100) according to any one of claims 1 to 7, characterized by , that a warning message indicating a required manual intervention is generated and issued if the switching contact (18) remains stuck after a predetermined number of vibration protocols have been performed. [9] Device (20) comprising a mechanical vibration device (22) and an evaluation and control unit (30) and configured to perform the method for releasing a switching contact (18) of a mechanical high-voltage switch (10) according to any one of claims 1 to 8, wherein the mechanical vibration device (22) is arranged externally on a housing (12) of the mechanical high-voltage switch (10) and is configured to generate vibrations and transmit them from the outside via the housing (12) to the switching contact (18), wherein the evaluation and control unit (30) is configured to control the mechanical vibration device (22) with at least one control signal having a predetermined frequency, a predetermined amplitude and a predetermined duration when an operating state of the mechanical high-voltage switch (10) with a high risk of sticking or a stuck switching contact (18) is detected. [10] Device (20) according to claim 9, characterized by, that the housing (12) of the high-voltage switch (10) is mounted in a vibration-damping manner.

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