Relay adhesion detection circuit and system

Abstract

The invention discloses a relay adhesion detection circuit and system. The detection circuit comprises a main loop, a voltage sampling circuit and an electrical isolation circuit, the main loop is used for connecting a power supply and a plurality of to-be-detected relays, and the to-be-detected relays are correspondingly connected with different loads; the voltage sampling circuit is in signal connection with the output ends of all the to-be-detected relays and is used for collecting voltage signals of all the to-be-detected relays in the on-off state so as to reflect the on-off state of all the to-be-detected relays; and the electrical isolation circuit is arranged between the voltage sampling circuit and the external control unit and is used for carrying out isolation transmission on the voltage signals acquired by the voltage sampling circuit, so that the external control unit judges whether the relays to be detected are adhered or not according to the voltage signals. According to the scheme, the accuracy of relay adhesion detection is improved, the spatial layout is optimized, the layout difficulty is reduced, the occupied space is reduced, and the detection cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of relay technology, specifically relating to a relay adhesion detection circuit and system. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the power distribution unit (PDU), as a core component of the vehicle's high-voltage electrical system, directly determines the safety and reliability of the entire vehicle's operation. Relays corresponding to critical loads such as the main drive, air conditioning, and oil pump in the PDU need to withstand high voltage and current of hundreds of amperes for extended periods. Under frequent switching, current surges, and high-temperature conditions, they are highly susceptible to contact oxidation, wear, or sticking. Once a relay sticks, the power supply cannot be properly cut off, potentially leading to irreversible safety risks such as surge current and thermal runaway upon the next power-on, seriously threatening the safety of the vehicle and its occupants.

[0003] To ensure driving safety, real-time detection of relay sticking status is necessary. Current technologies generally employ a design where one relay corresponds to one detection circuit, meaning each relay has independent voltage sampling, signal transmission, and isolation protection circuits to detect faults in a single relay. However, the internal space of a new energy vehicle's PDU is compact, and it needs to integrate multiple relays with functional loads. The traditional single-path corresponding detection scheme has inherent drawbacks: as the number of relays increases, the number of components, wiring harness length, and space occupied by the detection circuit also increase. This not only makes circuit board layout extremely difficult, hindering space optimization, but also significantly increases hardware costs and circuit complexity, ultimately affecting the integration and operational stability of the entire PDU system.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a relay adhesion detection circuit and system to solve the problems in related solutions where relay adhesion detection cannot simultaneously meet the requirements of detection accuracy and spatial layout optimization, resulting in large space occupation, high layout difficulty, and high cost. The invention achieves the effects of improving the accuracy of relay adhesion detection, optimizing spatial layout and reducing layout difficulty, reducing space occupation, and lowering detection cost.

[0006] This invention provides a relay sticking detection circuit, comprising: a main circuit, a voltage sampling circuit, and an electrical isolation circuit; the main circuit is used to connect a power supply to multiple relays to be tested, each relay being connected to a different load; the voltage sampling circuit forms a signal connection with the output terminals of all the relays to be tested, and is used to collect the voltage signal of each relay to be tested in the on / off state to reflect the on / off state of each relay to be tested; the electrical isolation circuit is disposed between the voltage sampling circuit and an external control unit, and is used to isolate and transmit the voltage signal collected by the voltage sampling circuit, so that the external control unit can determine whether each relay to be tested is stuck based on the voltage signal.

[0007] In some embodiments, the voltage sampling circuit includes multiple voltage divider circuits, each of which is connected to one of the relays to be tested. The signal outputs of all the voltage divider circuits are converged into a single signal and then connected to the electrical isolation circuit.

[0008] In some implementations, each voltage divider circuit includes multiple series-connected voltage divider resistors for graded voltage reduction processing of the voltage signal corresponding to the relay to be tested.

[0009] In some embodiments, the voltage sampling circuit further includes a voltage regulator element disposed in each group of voltage divider circuits to limit the fluctuation range of the output voltage of the corresponding voltage divider circuit to not exceed a preset value.

[0010] In some embodiments, the voltage sampling circuit further includes a filtering element connected to the signal output terminal of the voltage sampling circuit, which is used to filter out spike pulses and high-frequency interference signals in the voltage signal.

[0011] In some embodiments, the electrical isolation circuit includes an optocoupler, the input of which is connected to the signal output of the voltage sampling circuit, and the output of which is connected to the external control unit, thereby achieving electrical isolation through optical signal conversion.

[0012] In some embodiments, the electrical isolation circuit further includes a diode connected in series with the input terminal of the optocoupler to prevent reverse voltage from impacting the optocoupler.

[0013] In some embodiments, the main circuit is further provided with a protection element, which is connected in series with the relay under test to prevent reverse voltage from impacting the relay under test.

[0014] In some implementations, the external control unit compares the collected voltage signal with the preset voltage signal threshold corresponding to each of the relays to be tested in a preset on / off state to determine whether the relays to be tested are stuck together.

[0015] In conjunction with the aforementioned relay adhesion detection circuit, the present invention further provides a relay adhesion detection system, comprising: the aforementioned relay adhesion detection circuit.

[0016] In this invention, the main circuit of the relay sticking detection circuit connects a power supply to multiple relays to be tested, each corresponding to a different load. A voltage sampling circuit is connected to the output signals of all the relays to be tested and collects the voltage signals indicating their on / off states. An electrical isolation circuit is located between the voltage sampling circuit and an external control unit, isolating and transmitting the collected voltage signals for the external control unit to determine whether the relays are stuck. This improves the accuracy of relay sticking detection, optimizes the spatial layout and reduces layout difficulty, reduces space occupation, and lowers detection costs.

[0017] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the relay adhesion detection circuit. Figure 2 This is a schematic diagram of a relay adhesion detection circuit; Figure 3 This is a schematic diagram of the self-test process for the relay adhesion detection circuit. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] According to an embodiment of the present invention, a relay adhesion detection circuit is provided, which is as follows: Figure 1As shown, it includes: a main circuit, a voltage sampling circuit, and an electrical isolation circuit. The main circuit connects the power supply to multiple relays under test, each relay corresponding to a different load. The voltage sampling circuit forms a signal connection with the output terminals of all the relays under test, and is used to collect the voltage signal of each relay under test in its on / off state to reflect the on / off state of each relay. The electrical isolation circuit is located between the voltage sampling circuit and the external control unit, and is used to isolate and transmit the voltage signal collected by the voltage sampling circuit, so that the external control unit can determine whether each relay under test is stuck based on the voltage signal.

[0022] like Figure 2 As shown, the main circuit refers to the core circuit that connects the power supply, multiple relays K1-K6 to be tested, load equipment (air conditioner, electric heating, etc.) and protection components. It is the basic path for realizing the on / off control of the load power supply.

[0023] The main circuit provides operating voltage to the relays under test. When a relay receives an on / off command, its contacts close or open, thereby controlling the power supply to or off of the corresponding load. For example, when relay K1 corresponding to the air conditioner load closes, the air conditioner receives power; when it opens, the air conditioner is de-energized. Simultaneously, diodes in the main circuit prevent reverse voltage from impacting the relays, while resistors assist in monitoring the circuit current, ensuring stable operation of the main circuit.

[0024] The voltage sampling circuit is a circuit module containing six voltage-group circuits (including resistors R1-R24 and R25, diodes D1-D6, Zener diode ZD1, and capacitor C1) used to collect voltage signals under the on / off state of the relay to be tested, providing raw signals for adhesion judgment.

[0025] The voltage sampling circuit has six voltage divider circuits, each corresponding to a relay to be tested (e.g., the first voltage divider circuit R1-R4 corresponds to relay K1, and the second group R5-R8 corresponds to relay K2). All voltage divider circuits are connected to the output terminals of the relays. When a relay is closed, its output voltage is transmitted to the corresponding voltage divider circuit. After being divided by R1-R4 (or other group resistors), regulated by ZD1, and filtered by C1, a low-level signal is output. When the relay is open, the output voltage disappears, and the voltage divider circuit outputs a high-level signal.

[0026] Electrical isolation circuit refers to a circuit module consisting of an isolation optocoupler U and a diode, which is set between the voltage sampling circuit and the external control unit DSP to block the interference of the main circuit high voltage to the control unit.

[0027] Since the main circuit voltage of new energy vehicles can reach over 700V, directly transmitting the signal from the voltage sampling circuit to the external control unit could easily damage the control unit. Therefore, the isolation optocoupler in the electrical isolation circuit converts the sampled electrical signal into an optical signal. The optical signal is then transmitted to the output of the optocoupler and converted back into an electrical signal before being transmitted to the external control unit.

[0028] The external control unit DSP can receive signals transmitted via an isolated optocoupler and determine whether the relay under test is stuck by the voltage signal.

[0029] The external control unit pre-stores standard voltage signals for the relay under test in "command closed" and "command open" states (e.g., low level when closed, high level when open). When the actual voltage signal is received after isolation transmission, the control unit compares the actual signal with the standard signal: if the relay receives a closing command but the actual signal is high, or receives an opening command but the actual signal is low, then the relay is determined to have a sticking fault.

[0030] In some embodiments, the voltage sampling circuit includes multiple voltage divider circuits, each of which is connected to one of the relays to be tested. The signal outputs of all the voltage divider circuits are converged into a single signal and then connected to the electrical isolation circuit.

[0031] Six voltage divider circuits correspond one-to-one with the relays K1-K6 to be tested. During testing, each relay is controlled to turn on and off sequentially according to a preset order. Only one relay (the one currently being tested) is active at any given time, while the rest remain off. Only the voltage divider circuit corresponding to the currently tested relay receives a high-voltage signal input and outputs a valid level. The other untested relays, being off, receive no high-voltage input, resulting in no current flowing through their voltage divider circuits, and the Zener diode ZD1 is cut off, outputting an invalid high level. This avoids interference from invalid signals from untested relays with the current test result. Furthermore, the external control unit does not need to identify multiple signals; it only needs to read the level of a single converged signal to directly determine the status of the currently tested relay.

[0032] When the testing process reaches a specific relay (e.g., K1), only this relay receives the closing command and closes normally. The high-voltage signal generated at its output terminal is transmitted to the corresponding voltage divider circuit R1-R4. Current flows sequentially through R1, R2, R3, and R4, gradually reducing the high-voltage signal to the voltage range regulated by Zener diode ZD1 through a four-stage voltage divider. ZD1 conducts to stabilize the voltage, and capacitor C1 filters out high-frequency interference in the signal, ultimately forming a stable low-level effective signal output from the signal output terminal of this circuit. At this time, the other relays K2-K6 are all in the open state, and their corresponding voltage divider circuits R5-R24 have no high-voltage input and no effective output. When this relay receives the disconnect command and disconnects normally, its corresponding voltage divider circuit has no signal input and outputs a high-level effective signal, while the other voltage divider circuits remain at an ineffective high level.

[0033] Signal convergence ensures that only the circuit corresponding to the currently detected object outputs a valid level at any given time, while invalid high levels output by other circuits do not affect the transmission of the valid signal. For example, when detecting K1, only R1-R4 output a low level (valid signal), while R5-R24 output a high level (invalid signal). The converged single-channel signal is low (valid signal dominates, invalid high levels do not add interference). When detecting K2, only R5-R8 output the corresponding valid level, while the others output high levels, and the converged signal remains the current valid level. This convergence method does not require voltage superposition or timing coordination, nor does it require an external control unit to separate multiple signals. Only one valid signal exists at a time, and the external control unit can directly read the level of the single-channel converged signal to determine the on / off state of the currently detected relay.

[0034] The valid voltage level signal corresponding to the currently detected object is transmitted to the input terminal of the optocoupler in the electrical isolation circuit via the convergence path. The optocoupler converts the electrical signal into an optical signal, preventing the high voltage of the main circuit from being directly conducted to the external control unit. After the optical signal is transmitted internally by the optocoupler, it is restored to an electrical signal and then transmitted to the external control unit. The external control unit compares the actual received single-channel convergence signal level with the preset rules (the closing command corresponds to the expected low level, and the opening command corresponds to the expected high level): if a low level is received when the closing command is given and a high level is received when the opening command is given, the current detection relay is determined to be normal; if a high level is received when the closing command is given (cannot close) or a low level is received when the opening command is given (cannot open), the current detection relay is determined to be stuck.

[0035] In some implementations, each voltage divider circuit includes multiple series-connected voltage divider resistors for graded voltage reduction processing of the voltage signal corresponding to the relay to be tested.

[0036] The voltage at the output of the relay under test can reach hundreds of volts, far exceeding the tolerance range of the external control unit and electrical isolation circuit. If a single resistor is used for voltage division, not only will the resistor need to have an extremely high withstand voltage (increasing hardware costs and procurement difficulties), but the voltage signal may also fluctuate drastically due to excessively large single voltage drop, affecting the detection accuracy. However, when four resistors are connected in series, the total voltage is evenly distributed across each resistor according to the resistance value ratio, with each resistor only bearing a portion of the voltage load, achieving a graded voltage reduction process of "high voltage → multiple low voltage stages → target low voltage". This design reduces the withstand voltage requirement of a single resistor and allows for precise control of the final output voltage range by adjusting the number and resistance values ​​of the resistors, ensuring the stability of signal transmission.

[0037] The resistance values ​​of the four series resistors in each voltage-shaping circuit can be adapted to the voltage characteristics of the corresponding relay to be tested, ensuring that the relay voltage signals corresponding to different loads can be converted into a unified low-level range that is easy for external control units to compare through step-down.

[0038] In some embodiments, the voltage sampling circuit further includes a voltage regulator element disposed in each group of voltage divider circuits to limit the fluctuation range of the output voltage of the corresponding voltage divider circuit to not exceed a preset value.

[0039] The voltage regulator is a Zener diode ZD1. When the load corresponding to the relay under test is working, the output voltage may fluctuate momentarily due to factors such as load startup and current fluctuations. If the voltage is only stepped down in stages using voltage divider resistors, the fluctuating high voltage will still cause the output voltage to be unstable after voltage division. However, the Zener diode ZD1 has the characteristic of "voltage stabilization after reverse breakdown". Placing it in each voltage division circuit, it can conduct when the voltage after voltage division reaches the Zener voltage value of ZD1, clamping the voltage at a fixed value. Even if there are fluctuations in the input high voltage, the output voltage can remain stable, ensuring the accuracy and reliability of the signal received by the external control unit.

[0040] Each voltage regulator circuit can also be configured with a separate Zener diode, which can be matched with the voltage characteristics of the corresponding load to avoid the problem of poor voltage matching in some circuits caused by multiple circuits sharing a single Zener element.

[0041] In some embodiments, the voltage sampling circuit further includes a filtering element connected to the signal output terminal of the voltage sampling circuit, which is used to filter out spike pulses and high-frequency interference signals in the voltage signal.

[0042] The filtering element is a capacitor C1 connected in parallel. After the voltage sampling circuit uses voltage divider resistors to step down the voltage and Zener diodes to regulate it, the output voltage signal may still contain residual spikes (such as the instantaneous high voltage generated when relay K closes) and high-frequency interference (such as noise caused by the electromagnetic environment inside the vehicle). If these interference signals are directly transmitted to the electrical isolation circuit and the external control unit, it may cause the control unit to misjudge (such as misinterpreting a spike as a valid low level). As a filtering element, capacitor C1 has the characteristic of "passing AC and blocking DC". Spikes and high-frequency interference are AC signals and will be bypassed or absorbed by the capacitor, allowing only stable DC valid signals to pass through, thereby ensuring the purity of signal transmission.

[0043] In some embodiments, the electrical isolation circuit includes an optocoupler, the input of which is connected to the signal output of the voltage sampling circuit, and the output of which is connected to the external control unit, thereby achieving electrical isolation through optical signal conversion.

[0044] The load corresponding to the relay under test in the main circuit is a high-voltage load, with the main circuit voltage reaching over 700V during operation. However, the external control unit is a low-voltage sensitive device, typically withstanding only 3.3V or 5V. If the signal from the voltage sampling circuit is directly transmitted to the control unit, the high voltage may be conducted through the signal path, causing component burnout. Simultaneously, voltage fluctuations and electromagnetic interference in the main circuit may also affect the signal recognition accuracy of the control unit. Optocouplers, through photoelectric conversion, completely isolate the high-voltage circuit from the control circuit electrically, retaining only the logical consistency of the signal. This blocks the high-voltage conduction path and avoids the direct impact of electromagnetic interference, ensuring system safety and detection accuracy.

[0045] In some embodiments, the electrical isolation circuit further includes a diode connected in series with the input terminal of the optocoupler to prevent reverse voltage from impacting the optocoupler.

[0046] The signal transmitted from the voltage sampling circuit to the optocoupler may generate reverse voltage due to circuit abnormalities (such as voltage divider circuit failure or power fluctuations), or reverse current surges may occur during signal transmission. The input terminal of the optocoupler is an internal light-emitting diode (LED), which has weak reverse voltage withstand capability. If reverse voltage or current directly acts on the LED, it may cause the diode to break down and be damaged, leading to the failure of the electrical isolation circuit and the inability to achieve high-voltage isolation and signal transmission. The unidirectional conductivity of the diode can precisely block reverse voltage and current, allowing only the forward effective signal current to flow through the optocoupler input terminal, thus physically protecting the LED at the input terminal of the optocoupler and preventing damage from reverse surges.

[0047] In some embodiments, the main circuit is further provided with a protection element, which is connected in series with the relay under test to prevent reverse voltage from impacting the relay under test.

[0048] The protective components are diodes D1-D6. The loads corresponding to the relays under test in the main circuit are mostly high-voltage inductive loads. These loads generate a reverse electromotive force due to electromagnetic induction during start-up, shutdown, or power failure, resulting in a reverse voltage. Simultaneously, power fluctuations or circuit faults can also cause voltage polarity reversal. The relay contacts, which carry hundreds of amperes of current for extended periods, are already at risk of oxidation and sticking. The impact of reverse voltage further exacerbates contact wear and arcing, shortening the relay's lifespan and even directly inducing sticking failure. The diodes D1-D6, connected in series with the relay, utilize their unidirectional conductivity, allowing only forward operating current to pass through, blocking reverse voltage and current, thus protecting the relay contacts and coil from the source and reducing the factors that induce sticking failure.

[0049] In some implementations, the external control unit compares the collected voltage signal with the preset voltage signal threshold corresponding to each of the relays to be tested in a preset on / off state to determine whether the relays to be tested are stuck together.

[0050] The on / off state of the relay under test has a fixed correspondence with the voltage level signal. When normally closed, the voltage sampling circuit outputs a low level, which is transmitted to the external control unit after being converted by an optocoupler. When normally open, the voltage sampling circuit outputs a high level, the optocoupler is cut off, and the external control unit receives the high level. The external control unit compares the actual received signal with the standard by using a preset "command-level" correspondence standard, thereby deducing the true state of the relay and accurately identifying sticking faults.

[0051] Figure 2 In the circuit, power supplies VCC1-VCC6 are connected to relays K1-K6 respectively (loads include air conditioners, electric heaters, etc.). The output of each relay is connected in series with the corresponding group of resistors (e.g., K1 is connected to resistors R1, R2, R3, R4). The end of the resistor group is connected to a diode (e.g., R4 is connected to diode D1). The outputs of all diodes converge and are connected to Zener diode ZD1. At the same time, resistor R25 and capacitor C1 are connected in parallel, with one end connected to ZD1 and the other end grounded to GND2. The output of Zener diode ZD1 is connected to the input of optocoupler U1. The output of optocoupler U1 is connected in series with resistor R26 (connected to power supply VCC7) and then connected to the external control unit DSP. Optocoupler U1 is also grounded to GND3.

[0052] When a relay (e.g., K1) is closed, the high-voltage signal from the corresponding power supply is stepped down by resistors R1-R4, then transmitted unidirectionally to the convergence node via diode D1. After being stabilized by Zener diode ZD1 and filtered for interference by capacitor C1 and resistor R25, a low-level signal is input to optocoupler U1. Optocoupler U1 converts the electrical signal into an optical signal, then back into an electrical signal for transmission to the DSP. The DSP receives the low level signal and determines that the relay is closed normally. When the relay is open, there is no high-voltage signal input, optocoupler U1 is cut off, and the DSP receives a high level signal and determines that the relay is open normally. If the relay is stuck (e.g., K1 cannot be opened), it will continuously output a low level signal. The DSP receives a signal that does not match the expected command and determines that the relay is stuck.

[0053] Figure 3 The self-test procedure for the relay sticking detection circuit involves initiating a self-test after the system is powered on with low voltage. The self-test of each relay is initiated sequentially in the order of "Air Conditioner → Electric Heating → Electric Defrosting → Oil Pump → Air Pump → Main Drive". After each relay self-test is completed, its normality is checked. If normal, the self-test proceeds to the next relay; if abnormal, the corresponding fault is recorded, and the process continues to the next relay. Once all relay self-tests are complete, if all are normal, all relays are allowed to close and be energized. If abnormalities are found, all fault information is summarized and a relay sticking fault is reported to the instrument. This entire process achieves comprehensive troubleshooting of relay sticking faults and ensures that even if one relay fails, the self-tests of the remaining relays can still be completed, guaranteeing the integrity of the detection.

[0054] The technical solution of this embodiment connects the main circuit of the relay sticking detection circuit to the power supply and multiple relays to be tested corresponding to different loads. The voltage sampling circuit is connected to the output signal of all relays to be tested and collects the voltage signal of their on / off state. The electrical isolation circuit is located between the voltage sampling circuit and the external control unit to isolate and transmit the collected voltage signal, allowing the external control unit to determine whether the relay is stuck. This improves the accuracy of relay sticking detection, optimizes the spatial layout and reduces the layout difficulty, reduces the space occupied and lowers the detection cost.

[0055] According to embodiments of the present invention, a relay adhesion detection system corresponding to a relay adhesion detection circuit is also provided.

[0056] Since the processing and functions implemented by the relay adhesion detection system in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned relay adhesion detection circuit, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0057] The technical solution of this invention connects a power supply to multiple relays under test, each corresponding to a different load, in the main circuit of the relay sticking detection circuit. A voltage sampling circuit is connected to the output signals of all relays under test and collects the voltage signals indicating their on / off states. An electrical isolation circuit is located between the voltage sampling circuit and the external control unit, isolating and transmitting the collected voltage signals for the external control unit to determine whether the relays are sticking. This improves the accuracy of relay sticking detection, optimizes the spatial layout and reduces layout difficulty, reduces space occupation, and lowers detection costs.

[0058] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.

[0059] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of the claims.

Claims

1. A relay adhesion detection circuit, characterized in that, include: Main circuit, voltage sampling circuit, and electrical isolation circuit; The main circuit is used to connect the power supply and multiple relays to be tested, and the relays to be tested are connected to different loads. The voltage sampling circuit is connected to the output terminals of all the relays to be tested to collect the voltage signals of each relay to be tested in the on / off state, so as to reflect the on / off state of each relay to be tested. The electrical isolation circuit is located between the voltage sampling circuit and the external control unit. It is used to isolate and transmit the voltage signal collected by the voltage sampling circuit, so that the external control unit can determine whether each of the relays to be tested is stuck based on the voltage signal.

2. The relay adhesion detection circuit according to claim 1, characterized in that, The voltage sampling circuit includes multiple voltage divider circuits. Each voltage divider circuit is connected to one of the relays to be tested. The signal outputs of all the voltage divider circuits are converged into a single signal and then connected to the electrical isolation circuit.

3. The relay adhesion detection circuit according to claim 2, characterized in that, Each voltage divider circuit includes multiple series-connected voltage divider resistors for performing graded voltage reduction processing on the voltage signal of the corresponding relay to be tested.

4. The relay adhesion detection circuit according to claim 2, characterized in that, The voltage sampling circuit also includes a voltage regulator element, which is disposed in each group of voltage divider circuits to limit the fluctuation range of the output voltage of the corresponding voltage divider circuit to not exceed a preset value.

5. The relay adhesion detection circuit according to claim 1, characterized in that, The voltage sampling circuit also includes a filtering element, which is connected to the signal output terminal of the voltage sampling circuit and is used to filter out spike pulses and high-frequency interference signals in the voltage signal.

6. The relay adhesion detection circuit according to claim 1, characterized in that, The electrical isolation circuit includes an optocoupler, the input of which is connected to the signal output of the voltage sampling circuit, and the output of which is connected to the external control unit. Electrical isolation is achieved through optical signal conversion.

7. The relay adhesion detection circuit according to claim 6, characterized in that, The electrical isolation circuit also includes a diode connected in series with the input terminal of the optocoupler to prevent reverse voltage from impacting the optocoupler.

8. The relay adhesion detection circuit according to claim 1, characterized in that, The main circuit is also equipped with a protection element, which is connected in series with the relay under test to prevent reverse voltage from impacting the relay under test.

9. The relay adhesion detection circuit according to claim 1, characterized in that, The external control unit compares the collected voltage signal with the preset voltage signal threshold corresponding to each of the relays to be tested in a preset on / off state to determine whether the relays to be tested are stuck together.

10. A relay adhesion detection system, characterized in that, include: The relay adhesion detection circuit as described in any one of claims 1 to 9.

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