Method and system for detecting maloperation of magnetic latching relay

Abstract

The invention provides a method and a system for detecting maloperation of a magnetic latching relay. The method comprises the step of applying a driving signal gradually climbing from an initial voltage to a rated voltage to a coil of the magnetic latching relay. In the voltage climbing process, current changes of the coil are collected in real time, and the current waveform is obtained. Judging whether the magnetic latching relay has maloperation or not according to the occurrence frequency and fluctuation characteristics of inflection points in the current waveform: if the current waveform only has the inflection point for one time, judging that a product normally acts; and if the current waveform has multiple inflection points or abnormal fluctuations, judging that the product has maloperation. By accurately capturing the characteristics of the current waveform, quantitative detection of the maloperation phenomenon is achieved, and the defects that a traditional manual sound listening method is low in efficiency and a contact state detection method is missed in detection and jogging are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of relay detection, and in particular to a method and system for detecting malfunction of a magnetic latching relay. Background Art

[0002] Latching relays are energy-saving relays that use permanent magnets to maintain their contacts. They are controlled on and off by pulse signals, requiring no continuous power supply. They offer low power consumption, long life, and high reliability. They are widely used in smart meters, photovoltaic inverters, smart homes, industrial automation, and electric vehicle charging systems, and are particularly well-suited for circuit control scenarios requiring frequent switching or energy conservation.

[0003] However, during the manufacturing process, magnetic latching relays may experience false tripping when pulsed due to component tolerances, assembly errors, or fluctuations in material properties. This can lead to the relay failing to reliably complete its operation (e.g., the contacts only partially close or remain in an intermediate state). This false tripping can significantly reduce the overload capacity of the contacts and may even cause arcing due to poor contact, leading to equipment damage or fire risk. Therefore, rigorous false tripping detection of magnetic latching relays during production is crucial.

[0004] At present, there are two main detection methods in the industry:

[0005] Manual listening detection: An adjustable power supply pulses the relay, and the operator listens to determine whether the relay's sound is normal. If the sound is weak or jittery, it is considered a false alarm. However, this method relies on manual experience, is inefficient, and cannot be implemented on automated production lines.

[0006] Contact status monitoring: During the pulse drive process, the contact status is collected. If the contacts do not switch as expected, it is determined to be a false operation. However, this method can only identify false operations where the contacts have changed. It cannot effectively detect micro-movements (armature displacement but contact failure), resulting in some defective products being missed.

[0007] Due to the low efficiency and lack of accuracy of existing detection methods, there is an urgent need for a more efficient and reliable detection technology that can quickly and accurately identify the malfunction of magnetic latching relays during the production process, thereby improving product quality and reducing safety hazards. Summary of the Invention

[0008] In order to solve the above problems, the purpose of the present invention is to provide a method and system for detecting malfunction of a magnetic latching relay. By accurately capturing the above characteristics of the current waveform, quantitative detection of malfunction phenomena can be achieved, overcoming the defects of low efficiency of traditional artificial listening methods and missed detection of micro-movements by contact state detection methods.

[0009] The present invention is achieved through the following technical solutions:

[0010] A method for detecting malfunction of a magnetic latching relay, comprising:

[0011] S1. Apply a drive signal to the coil of the magnetic latching relay that gradually increases from the starting voltage to the rated voltage;

[0012] S2. During the voltage ramp-up process, real-time acquisition of the current change of the coil is performed to obtain the current waveform;

[0013] S3. Determine whether the magnetic latching relay malfunctions based on the number of occurrences and fluctuation characteristics of the inflection points in the current waveform:

[0014] If the current waveform has only one inflection point, it is determined that the product is operating normally;

[0015] If the current waveform has multiple inflection points or abnormal fluctuations, it is determined that the product has malfunctioned.

[0016] Furthermore, in S1 , the voltage rising rate of the driving signal changes linearly or nonlinearly, and the rising rate is adjustable.

[0017] Furthermore, in S3, the multiple inflection points include multiple drops and rises in the current waveform.

[0018] Furthermore, after completing the forward voltage rise detection, the method further includes performing a reverse action detection on the magnetic latching relay, the steps of:

[0019] S4: When the latching relay is a single-coil relay, switch the voltage polarity of the coil of the same latching relay and apply a drive signal to the coil that gradually increases from the starting voltage to the rated reverse voltage; when the latching relay is a dual-coil relay, apply a drive signal to the reset coil of the same latching relay that gradually increases from the starting voltage to the rated reset voltage;

[0020] S5. During the application of the driving signal, collecting the current change of the coil in real time to obtain a reverse current waveform;

[0021] S6. Determine whether the magnetic latching relay malfunctions during reverse operation based on the number of occurrences and fluctuation characteristics of the inflection points in the reverse current waveform:

[0022] If the current waveform has only one inflection point, it is determined that the product reset operation is normal;

[0023] If the current waveform has multiple inflection points or abnormal fluctuations, it is determined that the product reset has malfunctioned.

[0024] Furthermore, in S6, the multiple inflection points include multiple rise and fall phenomena in the current waveform.

[0025] Furthermore, the method of switching the voltage polarity includes using a reversing relay or an H-bridge circuit.

[0026] A system for detecting malfunction of a magnetic latching relay, for implementing the aforementioned method, comprising:

[0027] An adjustable voltage source, whose voltage output terminal is connected to the coil input terminal of the magnetic latching relay under test through a drive circuit, and is used to generate a drive signal that climbs from a starting voltage to a rated voltage at a preset rate;

[0028] A current acquisition module, comprising a sampling resistor connected in series in the coil loop, for acquiring the coil current signal in real time and converting it into a voltage signal containing the current signal;

[0029] The microprocessor includes: a digital-to-analog conversion output terminal connected to the control input terminal of the adjustable voltage source and used to output a voltage control signal; an analog-to-digital conversion input terminal connected to the output terminal of the signal amplification and filtering circuit and used to receive a voltage signal including a current detection signal; and a data processing unit configured to: control the adjustable voltage source to complete a voltage ramp-up process; analyze collected current waveform data to identify inflection point characteristics; and determine a malfunction state based on the number of inflection point occurrences and fluctuation characteristics.

[0030] Furthermore, the current acquisition module also includes a signal amplification and filtering circuit, which includes: a differential amplifier, whose positive and negative input terminals are respectively connected to the two ends of the sampling resistor, for extracting the differential voltage of the sampling resistor; a low-pass filter, whose input terminal is connected to the output terminal of the differential amplifier, for eliminating high-frequency noise, and whose output terminal is connected to the analog-to-digital conversion input terminal of the microprocessor.

[0031] Furthermore, the driving circuit includes an H-bridge circuit or a reversing relay, a control end of which is connected to the IO port of the microprocessor, for realizing voltage polarity switching of a single-coil relay or coil selection of a dual-coil relay.

[0032] Furthermore, the IO port of the microprocessor is connected to the driving circuit through an optocoupler isolation circuit to achieve electrical isolation.

[0033] Compared with the prior art, the technical solution of the present invention and its beneficial effects are as follows:

[0034] (1) This invention monitors the inflection points of the coil current waveform during voltage ramp-up and utilizes subtle changes in the current waveform to accurately identify malfunctions. Normal operation results in only one inductance inflection point, while malfunctions result in multiple inflection points / fluctuations due to repeated micro-movements of the armature. By utilizing current sampling and waveform analysis, the intermediate state and minute rotations of the armature can be quantitatively detected, addressing the problem of missed detection with traditional methods and significantly improving the accuracy of malfunction identification.

[0035] (2) The detection method of the present invention verifies the reliability of the setting / single-coil forward drive by forward detection and the stability of the reset / single-coil reverse drive by reverse detection. The relay is qualified only when there are no waveform abnormalities in both the forward and reverse directions. Through bidirectional full-process detection, the hidden dangers of the armature action and reset process can be comprehensively checked, and the malfunctioning products can be intercepted from entering the market at the production end, thereby strengthening the reliability of the on-off control of the magnetic latching relay and reducing the probability of equipment failure caused by malfunction of the relay.

[0036] (3) The detection system of the present invention has the adaptability to multiple scenarios: the voltage climbing rate is adjustable, the commutation circuit (electromagnetic relay / H-bridge optional), and the sampling resistor can be flexibly adjusted according to the relay specifications (single coil / dual coil, different rated voltages); at the same time, the microprocessor automatically controls the voltage drive, waveform analysis, and result judgment, replacing manual operation. The detection efficiency is much higher than the traditional manual method, adapting to the batch detection needs of the automated production line, taking into account both accuracy and production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the current waveform of the product with normal forward operation provided by the first embodiment of the present invention;

[0038] Figure 2 、 Figure 3 This is the current waveform of the product with malfunction in the forward direction provided by the first embodiment of the present invention;

[0039] Figure 4 This is a block diagram of a system for detecting malfunction of a magnetic latching relay provided in a second embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] A method for detecting malfunction of magnetic latching relay

[0043] S1. Voltage Ramp Drive: For the magnetic latching relay (single or dual coil) being tested, a drive signal is applied to its operating coil (single coil is positive polarity, dual coil is the set coil) through an adjustable voltage source, which increases from the starting voltage (0V) to the rated operating voltage at a preset rate. The voltage ramp rate can be set to linear or nonlinear (such as exponential) depending on the relay model, and the rate is adjustable to adapt to the testing requirements of products with different specifications and different sensitivities. For example, for a relay with a rated voltage of 12V, the ramp time can be set to 500ms, and the voltage can increase linearly from 0V to 12V.

[0044] S2. Current Signal Acquisition: During the voltage ramp, the coil current signal is collected in real time via a sampling resistor connected in series with the coil loop. This is converted into a voltage signal recognizable by the microprocessor and then transmitted to the microprocessor's analog-to-digital converter input. The acquisition frequency should be no less than 1kHz to ensure that even small current fluctuations are captured. In addition to sampling resistors, current transformers can also be used to collect current signals.

[0045] S3. Current waveform analysis and malfunction determination: The data processing unit of the microprocessor analyzes the collected current waveform data and identifies the inflection point features in the waveform.

[0046] If the current waveform has only one obvious inflection point (i.e., a sudden change in the current rising rate due to a sudden change in inductance), it indicates that the relay can reliably operate when the voltage reaches the action threshold, and the forward action is normal. Figure 1 ;

[0047] If the current waveform has multiple inflection points (such as two or more drops and then rises) or small abnormal fluctuations, such as Figure 2 、 Figure 3 , indicating that the relay has armature micro-movement or intermediate state during the operation process, and it is judged that there is false operation in the forward action.

[0048] To ensure that there is no abnormality in the relay during the reset process, a reverse action test is required after completing the forward test.

[0049] S4, reverse drive signal application:

[0050] For a single-coil latching relay, the coil voltage polarity is switched, and a drive signal is applied to the coil that ramps from a starting voltage (0V) to a rated reverse voltage at a preset rate. The reverse voltage amplitude can be the same as the rated forward voltage, or different, but with opposite polarity. Switching the coil voltage polarity can be accomplished using either a reversing relay or an H-bridge circuit. Electromagnetic reversing relays are low-cost and suitable for low-frequency testing, while H-bridge circuits, comprised of MOS transistors, offer fast response and are suitable for high-speed automated testing lines.

[0051] For a dual-coil magnetic latching relay: directly apply a drive signal to its reset coil, which increases from the starting voltage (0V) to the rated reset voltage at a preset rate.

[0052] S5. Reverse current signal acquisition: During the reverse voltage rising process, the coil current signal is collected in real time and transmitted to the microprocessor after processing.

[0053] S6. Reverse waveform analysis and malfunction determination

[0054] The microprocessor analyzes the reverse current waveform:

[0055] If the current waveform has only one obvious inflection point, it indicates that the relay is reliably reset and the reverse action is normal;

[0056] If the current waveform has multiple inflection points (such as multiple rises and falls) or abnormal fluctuations, it indicates that there is micro-movement of the armature during the reset process, which is judged as a false operation in the reverse action.

[0057] Malfunctions in magnetic latching relays are caused by micro-motion of the armature (unreliable actuation or an intermediate state) due to component tolerances or assembly errors. The core principle is that during normal relay operation, the balance between the coil's magnetic field and the force acting on the permanent magnet is disrupted, causing the armature to rotate reliably once, resulting in a sudden change in coil inductance, generating a reverse electromotive force (EMF) and a single inflection point in the current waveform. During voltage ramping, a malfunctioning relay experiences multiple small rotations (micro-motions) of the armature due to unstable force. Each rotation causes a sudden change in inductance, generating multiple reverse electromotive forces and causing multiple inflection points or fluctuations in the current waveform.

[0058] This embodiment achieves quantitative detection of malfunction phenomena by accurately capturing the above-mentioned characteristics of the current waveform, overcoming the defects of low efficiency of the traditional artificial listening method and missed detection of micro-movements by the contact state detection method.

[0059] Example 2

[0060] See Figure 4 , a system for detecting malfunction of a magnetic latching relay, comprising:

[0061] An adjustable voltage source, with its voltage output connected to the relay coil input under test via a driver circuit, generates a drive signal under microprocessor control that ramps from 0V to a rated voltage (forward or reverse) at a preset rate (linear or nonlinear). Its control input, connected to the microprocessor's digital-to-analog converter output, receives a voltage control signal to adjust the output voltage ramp rate and target value.

[0062] The current acquisition module includes a sampling resistor connected in series in the coil loop, which is used to acquire the coil current signal in real time. It also includes a signal amplification and filtering circuit, which includes a differential amplifier and a low-pass filter. The positive and negative inputs of the differential amplifier are respectively connected to the two ends of the sampling resistor to extract the voltage difference across the sampling resistor. The input of the low-pass filter is connected to the output of the differential amplifier, and the output of the low-pass filter is connected to the analog-to-digital conversion input of the microprocessor (see below) to eliminate high-frequency noise. The purified voltage signal, which includes the current signal, is output to the analog-to-digital conversion input of the microprocessor.

[0063] The microprocessor includes a digital-to-analog converter output, an analog-to-digital converter input, and a data processing unit. The digital-to-analog converter output outputs a voltage control signal to the adjustable voltage source, precisely controlling the voltage ramp. The analog-to-digital converter input receives the amplified and filtered voltage signal and converts it into a digital signal. The data processing unit controls the start and stop of the adjustable voltage source and controls the voltage parameters. It also reconstructs the waveform of the collected digital current signal, identifying inflection points by slope changes. Based on the number of inflection points and fluctuation characteristics of the forward and reverse waveforms, it outputs a false trip determination result.

[0064] The drive circuit includes a reversing relay or an H-bridge circuit composed of MOS transistors. Its control terminal is connected to a microprocessor's I / O port, and the microprocessor controls the voltage polarity. The control terminal of the drive circuit can be connected to the processor's I / O pin via an optocoupler to achieve electrical isolation and prevent interference. For dual-coil relays, the drive circuit is a coil selection circuit, with the microprocessor controlling the selection of the set coil or reset coil.

[0065] The detection system of this embodiment further includes a display module, which is connected to the microprocessor and is used to display waveforms.

[0066] While the foregoing description shows and describes preferred embodiments of the present invention, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments, and can be modified within the scope of the present invention by the teachings herein or by techniques or knowledge in the relevant art. Modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention are intended to be within the scope of the appended claims.

Claims

1. A method for detecting malfunction of a magnetic latching relay, characterized in that: include: S1. Apply a drive signal to the coil of the magnetic latching relay that gradually increases from the starting voltage to the rated voltage; S2. During the voltage ramp-up process, the current change of the coil is collected in real time to obtain the current waveform; S3. Determine whether the magnetic latching relay malfunctions based on the number of occurrences and fluctuation characteristics of the inflection points in the current waveform: If the current waveform has only one inflection point, it is determined that the product is operating normally; If the current waveform has multiple inflection points or abnormal fluctuations, it is determined that the product has malfunctioned.

2. A method for detecting malfunction of a magnetic latching relay according to claim 1, characterized in that: In S1, the voltage rising rate of the driving signal changes linearly or nonlinearly, and the rising rate is adjustable.

3. The method for detecting malfunction of a magnetic latching relay according to claim 1, wherein: In S3, the multiple inflection points include multiple drops and rises in the current waveform.

4. The method for detecting malfunction of a magnetic latching relay according to claim 1, wherein: The method further includes performing a reverse action detection on the magnetic latching relay after completing the forward voltage rise detection, the steps of which are as follows: S4: When the latching relay is a single-coil relay, switch the voltage polarity of the coil of the same latching relay and apply a drive signal to the coil that gradually increases from the starting voltage to the rated reverse voltage; when the latching relay is a dual-coil relay, apply a drive signal to the reset coil of the same latching relay that gradually increases from the starting voltage to the rated reset voltage; S5. During the application of the driving signal, collecting the current change of the coil in real time to obtain a reverse current waveform; S6. Determine whether the magnetic latching relay malfunctions during reverse operation based on the number of occurrences and fluctuation characteristics of the inflection points in the reverse current waveform: If the current waveform has only one inflection point, it is determined that the product reset operation is normal; If the current waveform has multiple inflection points or abnormal fluctuations, it is determined that the product reset has malfunctioned.

5. The method for detecting malfunction of a magnetic latching relay according to claim 1, wherein: In S6, the multiple inflection points include multiple rise and fall phenomena in the current waveform.

6. The method for detecting malfunction of a magnetic latching relay according to claim 1, wherein: Methods for switching the voltage polarity include using a reversing relay or an H-bridge circuit.

7. A system for detecting malfunction of a magnetic latching relay, for implementing the method according to any one of claims 1 to 6, characterized in that: include: An adjustable voltage source, whose voltage output terminal is connected to the coil input terminal of the magnetic latching relay under test through a drive circuit, and is used to generate a drive signal that climbs from a starting voltage to a rated voltage at a preset rate; A current acquisition module, comprising a sampling resistor connected in series in the coil loop, for acquiring the coil current signal in real time and converting it into a voltage signal containing the current signal; Microprocessor, including: A digital-to-analog conversion output terminal connected to the control input terminal of the adjustable voltage source for outputting a voltage control signal; an analog-to-digital conversion input terminal connected to the output terminal of the signal amplification and filtering circuit, and configured to receive a voltage signal including a current detection signal; The data processing unit is configured to: control the adjustable voltage source to complete the voltage climbing process; analyze the collected current waveform data to identify the inflection point characteristics; and determine the malfunction state according to the number of inflection point occurrences and fluctuation characteristics.

8. The system according to claim 7, characterized in that The current acquisition module further includes a signal amplification and filtering circuit, which includes: A differential amplifier, whose positive and negative input terminals are respectively connected to the two ends of the sampling resistor, is used to extract the differential voltage of the sampling resistor; A low-pass filter has an input end connected to the output end of the differential amplifier for eliminating high-frequency noise, and an output end connected to the analog-to-digital conversion input end of the microprocessor.

9. The system according to claim 7, wherein: The driving circuit includes an H-bridge circuit or a reversing relay, a control end of which is connected to the IO port of the microprocessor, and is used to realize voltage polarity switching of a single-coil relay or coil selection of a double-coil relay.

10. The system according to claim 9, characterized in that The IO port of the microprocessor is connected to the drive circuit through an optical coupling isolation circuit to achieve electrical isolation.

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