Method for operating an electromechanical switching element

Abstract

A method for operating an electromechanical switching element having at least a plurality of contacts, a coil with a core, and an armature, wherein, in the event of a given condition being met, at a given time in the overtravel region, during opening, opening and closing pulses of the switching element are performed multiple times, or, during closing, closing and opening pulses of the switching element are performed multiple times, such that the coil current flowing into the coil oscillates between a given maximum value and a minimum value, such that the armature is moved in the overtravel region and, as a result, the contacts rub against one another without detaching from one another, wherein the minimum value is defined as the current value at the time at which the armature begins to detach from the core.

Description

Technical Field

[0001] The present invention relates to a method for controlling an electromechanical switching element, and a general component. Background Technology

[0002] When switching electromechanical switching elements such as relays, two types of failures may occur. In one case, the relay fails to make contact during the opening process; in the other case, the current flow through the contacts cannot be interrupted during the closing process. The causes of these failures are varied, including, for example, mechanical jamming of the contacts, oxide buildup, and solder joints. However, many of these causes are reversible; that is, when contacts are mechanically jammed, for example, they can still be released again, and the relay can continue to be used for thousands of switching cycles. Therefore, the faulty switching state of the relay can be corrected by reoperation.

[0003] In DE102014211400A1, when the contacts of the contactor are in contact with a contact resistance not less than a specified value, the contactor performs at least one opening and closing operation.

[0004] In EP3185269B1, the operating current is superimposed on the electrical waveform. This method can only be used during the disconnection process.

[0005] Known measures include, for example, repeating the switching process and applying vibration to the contacts. Measurement techniques for obtaining contact status are also known, for example, from DE102018114425 A1 or WO 202194418 A1.

[0006] However, known methods still need improvement to prevent switching element failure or to delay failure. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide a method for controlling electromechanical switching elements, by which the contact elements can be prevented from sticking or can be detached again.

[0008] The proposed method is for controlling an electromechanical switching element having at least multiple contacts, a coil with an iron core, and an armature. Under given conditions, at a given moment within the overtravel region, during the disconnection process, multiple on / off pulses of the switching element are executed, or during the connection process, multiple off / on pulses of the switching element are executed, causing the coil current flowing into the coil to oscillate between a given maximum and minimum value, causing the armature to move within the overtravel region, thereby causing the contacts to rub against each other without disengaging from each other. The minimum value is defined as the current value at the moment the armature begins to disengage from the iron core.

[0009] In another embodiment, the given condition is that a fault state is identified in which the contacts do not make contact when connected or do not disengage when disconnected, or in which the given condition is that a deterioration in the contact quality of the contacts is detected.

[0010] In another embodiment, the on-time or off-time is selected to be long enough that the coil current reaches the value that the coil current has at a given moment after being turned off or on.

[0011] In another embodiment, it is specified that an overtravel region is continuously determined for each electromechanical switching element during use, and if the overtravel region changes during the service life, the given time of the on or off pulse is adjusted within the overtravel region.

[0012] Another implementation scheme specifies that continuous monitoring is performed to determine whether a given condition is met.

[0013] In another embodiment, a general-purpose component is provided, comprising: an electromechanical switching element having a plurality of contacts and an armature, wherein the armature is configured such that moving the contacts causes them to come into contact or disengage from each other; an integrated measurement technique for determining at least one overtravel region during operation of the electromechanical switching element; and a microcontroller signal-connected to the electromechanical switching element, in which the method is implemented as a software program.

[0014] In another embodiment, the general-purpose component is configured as a relay socket.

[0015] Other features and advantages of the invention will become apparent from the following description of embodiments of the invention and with reference to the accompanying drawings, which illustrate details according to the invention. In variations of the invention, the various features may be implemented individually or in any combination. Attached Figure Description

[0016] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These drawings show:

[0017] Figures 1-3 Views are shown of electromechanical switching elements in different switching states according to the prior art.

[0018] Figure 4 A diagram illustrating a normal circuit breaking process and contact friction is shown according to an embodiment of the present invention. Detailed Implementation

[0019] In the following description of the accompanying drawings, the same elements or functions are given the same reference numerals.

[0020] The proposed method is applied in products having an electromechanical switching element 10, which has multiple contacts 7a, 7b, 7c and an armature 5. In particular, the proposed electromechanical switching element 10 of the present invention is incorporated into general-purpose components such as universal sockets, which are used, for example, in industrial automation (DC industrial power grids) or in charging stations for electric vehicles, etc. The electromechanical switching element 10 used herein typically cannot be configured directly after production or based on one or more reference components because different influencing factors, such as the type of switching element, control voltage, mounting position, and installation location, play a role depending on the usage scenario, i.e., the type of switching element, and may alter the switching characteristics of the switching element.

[0021] Therefore, according to the present invention, the electromechanical switching element 10 is operated directly at the installation location to reduce malfunctions. That is, the operation method is performed within a universal assembly. For this purpose, not only measurement technology but also a microcontroller is required, and said measurement technology and microcontroller are incorporated into the universal assembly. The universal assembly can here be implemented as a relay socket.

[0022] The following discussion pertains only to the relay 10 as an electromechanical switching element 10. However, this method can also be used for other electromechanical switching elements, such as contactors. Furthermore, in addition to the embodiment shown herein, where the changeover contact is part of the electromechanical switching element 10, this type of changeover contact can also be integrated into other devices, such as changeover switches.

[0023] exist Figure 1 The diagram illustrates a schematic of a three-pole changeover contact according to a general embodiment. Currently, the changeover contact is, exemplarily, part of an electromechanical switching element 10 or a changeover relay. The electromechanical switching element 10 includes three interfaces assigned to the changeover contacts, and these interfaces are conventionally referred to below as COM interface (“common”) 2a, NC interface (normally closed) 2b, and NO interface (normally open) 2c. Furthermore, the electromechanical switching element 10 includes two relay coil interfaces 3a and 3b, through which a coil current I3 can be supplied to the relay coil 3 (also simply referred to as coil 3) of the electromechanical switching element 10. With the flow of current, the relay coil 3 establishes a magnetic field, which is guided in a magnetic core 4 and applies force to a movable relay armature 5 (also simply referred to as armature 5), which in turn causes movement of one or more contacts 7a, 7b, 7c (also referred to as contact elements or contact pieces) assigned to the respective interfaces 2a, 2b, 2c via a slider 6.

[0024] exist Figure 1The diagram shows the relay 10 in the open state, i.e., contacts 7a and 7b are abutting each other. Figure 2 The diagram shows the relay in the closed state, i.e., contacts 7a and 7c are abutting each other. Figure 3 The diagram illustrates what is known as overtravel. Here, contact 7a rests against contact 7c (relay 10 is closed), and contact 7a is pressed against contact 7c by slider 6 operated by armature 5, as shown by the bending of the upper end of contact 7a. When relay 10 is on and off, there exists a region where contacts 7a and 7c are in contact, but armature 5 is not in contact with coil 3 (more specifically, iron core 8). That is, the connection between contacts 7a and 7c is already conductive, but the bending state of the contact elements is still changing; this region is referred to below as the overtravel region.

[0025] exist Figure 4 The diagram shows the time curve of the disconnection process of an electromechanical switching element 10, for example, constructed as a relay, according to the prior art. A standardized measurement parameter x / X is given on the vertical axis. max Here, region B0 represents the closed state of relay 10, that is, the armature 5 is attracted to the coil 3, or more precisely, the armature is not in contact with the coil 3, but in contact with the yoke or iron core 8, and in regions B1 and B2, the armature is disengaged from the yoke or iron core 8, and contacts 7a and 7c are abutting each other (as shown in the image). Figure 2 As shown), this results in conductivity (represented by the dashed line L1). Region B1 indicates an overtravel state (such as...). Figure 3 As shown), although armature 5 is disengaged from coil 3, contacts 7a and 7c are not yet disengaged from each other. Area B2 shows the open state of relay 10, that is, contacts 7a and 7c are disengaged from each other, so that there is no longer any conductivity between contacts 7a and 7c (as shown). Figure 1 As shown in the diagram. The solid line represents the coil current I3. It can be seen that during the circuit breaking process, the coil current I3 decreases until it reaches its maximum at time t. 01 The minimum current is reached. This minimum current is defined by the disengagement of armature 5 from the iron core 8 of coil 3 (and can be detected immediately after disengagement). The moment t when armature 5 begins to disengage... 01 The coil current I3 rises again, which can be determined, for example, by calculation using the derivative (from a negative value to a positive value). At that moment t 01 The transition from region B0 to region B1 (overtravel) occurs at the moment when contacts 7a and 7c open. 12 At this point, the device leaves the overtravel zone B1 (enters zone B2, where contacts 7a and 7c are in the open state). Time period d 02 Indicates t 01 and t 12During the time interval between these two periods, although armature 5 is detached from the iron core 8 of coil 3, contacts 7a and 7c remain in contact with each other.

[0026] The object of this invention is to identify faulty switching states and automatically correct them, preventing contacts 7a / 7b or 7a / 7c from disengaging from each other, or contacts 7a / 7b or 7a / 7c from contacting each other but not conducting in the faulty switching state. This is achieved by re-energizing the armature 5 within the overtravel region B1, thereby moving contacts 7a and 7c and causing them to rub against each other, as described below. Here, the disconnection process, i.e., the disconnection process of contacts 7a and 7c, is particularly considered. However, the proposed method can also be applied during the connection process. Depending on the installation, there are two disconnection faults (NO 2c-COM 2a; COM 2a-NC 2b) in the converter, but there are also connection faults for these contact pairs, thus correcting a total of four faults in the switching relay: contacts NO 2c-COM 2a not disengaging, NO 2c-COM 2a not conducting, COM 2a-NC 2b not disengaging, and COM 2a-NC 2b not conducting. Since the following text focuses on the disconnection process, this method will only be described using contacts 7a and 7c. The corresponding parameters, such as I1 and t... ein d ein L2 additionally written to Figure 4 This is to explain how the method works.

[0027] The excitation, (because the complete turn-on process was not executed), in this embodiment is a reconnection or activation pulse, within the overtravel region B1, i.e., during time period d. 02 The time t within ein This is done at [location]. Advantageously, this choice of time t... ein , making it similar to t 01 and t 12 There is a time interval. Time t ein The choice of can be arbitrarily implemented using a microcontroller. From that time t ein Initially, the coil current (hereinafter referred to as I1) rises again (in Figure 4 China and Israel from t ein (As shown by the initial scribing), this prevents contacts 7a and 7c from disengaging. However, these contacts are still energized in the overtravel region and move relative to each other along different trajectories by spring force, causing the contacts to rub against each other or causing force to be applied to the contact connection point. During the re-increase of the coil current I1, contacts 7a and 7c press against each other again. If the coil current I1 reaches a given value at time t during the circuit breaking process... ausIf the selected current value is applied, the circuit is disconnected again, thereby re-energizing contacts 7a and 7c. These contacts then move relative to each other along different trajectories due to spring force, causing them to rub against each other or applying force to the contact connection point. This can be repeated multiple times. Therefore, contacts 7a and 7c generate friction, but they do not disengage from each other, meaning a complete switching cycle is not experienced. Switching element 10 is thus fully conductive during contact friction. The coil current I3 (I1) therefore oscillates between a (given, freely chosen) maximum current and a (limited by armature 5 disengagement) minimum current, thereby always causing armature 5 to move within the overtravel region B1.

[0028] Here, in Figure 4 The maximum current (maximum coil current I3) and minimum current (its value at time t) are represented by "1" on the vertical axis. 01 Choose the moment t at any position between (existing) to break off. aus In this embodiment, time t is selected at approximately 2 / 3 of the full-coil current I3. aus However, another disconnection time t can also be selected based on the control. aus And thus select another disconnected coil current I3. For example, excitation can be performed in a band of 90% to 40% of the coil current I3.

[0029] From the selected time t aus and connection time t ein The duration of disconnection d is obtained from this. aus Connection duration d ein From the connection time t ein With time t aus2 The time interval between these intervals is calculated, and at that time t aus2 Above, the coil current I1 reaches the same level as at time t. aus The disconnected coil current I3 is at the same height. (Due to d) aus and d ein The sum of these values ​​yields the frequency of the (pulse width) signal used for manipulation, and is derived from d. aus and d ein The duty cycle of the signal is derived from the ratio. Preferably, a high frequency of 50Hz or higher is achieved; in this embodiment, it is 200Hz.

[0030] Advantageously, the method is terminated as soon as possible when contacts 7a and 7b are detected to have successfully made contact (when the circuit is closed) or contacts 7a and 7c are detected to have disengaged (when the circuit is open). Advantageously, monitoring is performed continuously or at given intervals. If the corresponding detection cannot be performed after a given time period, relay 10 is de-circuited and a fault signal is issued.

[0031] Therefore, the proposed re-excitation results in contacts 7a and 7c rubbing against each other multiple times, but without opening (not separating), thus maintaining a conductive connection between the contacts, as if by... Figure 4 As indicated by dotted line L2 in the diagram. The term "multiple times" can be understood as (during the disconnection process) repeatedly turning on and off pulses multiple times or (during the connection process) repeatedly turning off and on pulses multiple times, preferably continuously, until no more fault conditions are obtained, wherein limits can be set on the duration or frequency of the friction.

[0032] Furthermore, a complete switching cycle is not experienced during excitation. Instead, within the overtravel region B1, i.e., the time period d between the disengagement of armature 5 and the disengagement of contacts 7a and 7c. 02 Within, at time t ein At this point, a new stimulus occurs before contacts 7a and 7c separate from each other.

[0033] This method is event-based and advantageously executed when a fault condition is identified, i.e., when contacts 7a and 7c are not disengaged or when a conductive connection cannot be re-established due to deposits. The contaminants between the contacts are removed or the coated material is worn away by friction generated by multiple on-off pulses (during the disconnection process) or multiple off-on pulses (during the connection process).

[0034] However, this method can also be executed under conditions different from the currently identified fault state, such as preventative execution. This method can be executed based on the identification of a predictable fault state, i.e., preventative execution. Here, for example, if vibration is detected in the coil current I3 at the end of the switching process, it can be inferred that the switching element 10 is in a degraded state (deterioration in the contact quality of contacts 7a, 7b, and 7c). Here, although a fault state has not yet been obtained, in which contacts 7a and 7c no longer separate from each other (when relay 10 is open) or (when relay 10 is closed) do not form a conductive connection, the fault state is already predictable and therefore expected. Thus, this method can be executed preventatively.

[0035] In a less preferred embodiment, the method may also be performed preventively after a fixed number of switching processes of relay 10.

[0036] As already mentioned, this method can be performed not only during the connection process but also during the disconnection process, because a fault state can occur in both processes, namely, contacts 7a / 7c and 7a / 7b do not disconnect from each other or are not conducting.

[0037] To implement this method, data (coil current I3, time t) is collected during each switching process when the electromechanical switching element 10 is first used, i.e., after it is installed in the application, so that the overtravel region B1 can be determined. As mentioned above, this can be determined from the time difference between the first sign change of the time derivative of the coil current and the first change in the conductivity of contacts 7a / 7c, 7a / 7b. By acquiring data in every switching process as much as possible, the overtravel region B1 can be adjusted, for example, due to aging of the relay 10 during its service life. Therefore, this method is adaptive.

[0038] To acquire data and perform adjustments, a general-purpose component is provided. This component not only possesses the necessary measurement techniques, such as those for measuring current, but also includes a microcontroller capable of performing the corresponding calculations and controlling the relay 10. Within the microcontroller, this method is implemented as a software program. This method is also used, for example, to control the relay 10 using a PWM signal.

[0039] The advantages of this method are that it prevents numerous equipment failures caused by faulty relays 10. Furthermore, the system has a low response time, allowing the equipment to continue operating uninterrupted. Another advantage is that friction can be immediately stopped without reconnection, as there is no vibration behavior. Moreover, the technical implementation as a self-sufficient, universal switching assembly ensures minimal application workload for the user. Attached Figure Description

[0041] 2a COM interface

[0042] 2b NC interface

[0043] 2c NO interface

[0044] 3. Relay coil

[0045] 3a, 3b Relay coil interface

[0046] 4. Magnetic core

[0047] 5. Relay armature

[0048] 6 sliders

[0049] 7a-7c Contact elements

[0050] 8 Iron core

[0051] 10. Electromechanical switching elements, such as relays

[0052] Armature position when B0 contact is closed

[0053] B1 Armature position during overtravel (overtravel region)

[0054] Armature position with B2 contact open

[0055] I3 coil current

[0056] I1 Coil current during friction

[0057] I3_max and I1_max are the maximum values ​​of the coil current.

[0058] I3_min Minimum coil current

[0059] L1, L2 conductivity

[0060] t time

[0061] t aus Disconnection time

[0062] t aus2 The moment of friction break

[0063] t ein Connection time

[0064] t 12 When the contact opens

[0065] t 01 The moment the armature disengages

[0066] d 02 Time period / Duration of over-trip

[0067] d aus Disconnection duration

[0068] d ein Connection duration

Claims

1. A method for controlling an electromechanical switching element (10), said electromechanical switching element having at least a plurality of contacts (7a, 7b, 7c), a coil (3) with an iron core (8), and an armature (5), wherein - Under the given conditions - At a given time (t) within the overtravel region (B1) ein At point ), during the disconnection process, the switching element (10) is repeatedly activated and deactivated, or during the connection process, the switching element (10) is repeatedly activated and deactivated, causing the coil current (I3, I1) flowing into the coil (3) to oscillate between a given maximum value (I3_max; I1_max) and a minimum value (I3_min), thereby causing the armature (5) to move within the overtravel region (B1), and thus causing the contacts (7a, 7b, 7c) to rub against each other without disengaging from each other. in, The minimum value (I3_min) is defined as the moment (t) when the armature (5) begins to separate from the core (8). 01 The current value at ().

2. The method according to claim 1, wherein, The given condition is to identify a fault state in which the contacts do not make contact when connected or do not disengage when disconnected, or wherein the given condition is to detect a deterioration in the contact quality of the contacts (7a, 7b, 7c).

3. The method according to claim 1, wherein, Connection duration (d) ein The disconnection or on-off duration is chosen to be such that the coil current (I1) reaches the coil current at a given time (t0) after disconnection or on-off. aus The value that is present at location ).

4. The method according to claim 1, wherein, For each electromechanical switching element (10), the overtravel region (B1) is continuously determined during use, and if the overtravel region changes during the service life, the given time (t) of the turn-on pulse or turn-off pulse is adjusted within the overtravel region (B1). ein ).

5. The method according to claim 1, wherein, Continuous monitoring is performed to determine whether the given conditions are met.

6. A general-purpose component (100) having: - An electromechanical switching element (10) having a plurality of contacts (7a, 7b, 7c) and an armature (5), wherein the armature is configured to move the contacts (7a, 7b, 7c) such that the contacts come into contact with or disengage from each other, and - Integrated measurement technology for determining at least one overtravel region (B1) during the operation of an electromechanical switching element (10), and - A microcontroller connected to an electromechanical switching element (10) in a signal connection, wherein the method according to any one of the preceding claims is implemented as a software program.

7. The general-purpose component (100) according to claim 6 is configured as a relay socket.

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