Relay state monitoring circuit and system, and insulation and voltage resistance test system

Abstract

The utility model discloses a state monitoring circuit and system of a relay and an insulation and voltage resistance test system, which are applied to the field of relays, and because a first voltage detection circuit and a second voltage detection circuit are respectively connected to two ends of the relay, the first voltage of the first detection circuit is the voltage of one end of the relay, and the second voltage of the second detection circuit is the voltage of the other end of the relay. The second voltage of the second voltage detection circuit is the voltage of the other end of the relay. The resistance value of the first voltage detection circuit and the resistance value of the second voltage detection circuit are both larger than the resistance value of the relay, so that the first voltage detection circuit and the second voltage detection circuit share more voltage, and the state determination circuit can collect the first voltage and the second voltage. Even if the relay is closed, the voltage difference of the relay can be determined through the collected first voltage and second voltage, and the state of the relay can be effectively monitored based on the voltage difference of the relay.

Description

Technical Field

[0001] The present application relates to the field of relays, and particularly to a relay status monitoring circuit and system, and an insulation withstand voltage test system. Background Art

[0002] In order to ensure the safety performance of electrical equipment, it is necessary to perform an insulation withstand voltage test on the electrical equipment. A relay is usually provided in the circuit loop where the electrical equipment is located. If the status of the relay is abnormal, it may cause a high potential difference to form between the main circuit board where the electrical equipment is located and the high-voltage line, resulting in a low insulation resistance value and misjudgment, thereby affecting the accuracy of the insulation withstand voltage test result. Therefore, before performing an insulation withstand voltage test on the electrical equipment, it is necessary to monitor the status of the relay in advance.

[0003] In the related art, the relay status monitoring circuit may include a digital-to-analog converter and a controller. Among them, one end of the digital-to-analog converter is connected to both ends of the relay, and the other end of the digital-to-analog converter is connected to the controller. The analog-to-digital converter is used to collect the pressure difference of the relay, and the controller is used to determine the status of the relay based on the pressure difference collected by the analog-to-digital converter.

[0004] However, when the relay is closed, its internal resistance is small. At this time, the analog-to-digital converter may not be able to collect the pressure difference of the relay, resulting in an inability to effectively monitor the status of the relay. Utility Model Content

[0005] In view of the above problems, the present application provides a relay status monitoring circuit and system, and an insulation withstand voltage test system, which can solve the problem that the status of the relay cannot be effectively monitored when the relay is closed in the related art.

[0006] On the one hand, a relay status monitoring circuit is provided. The status monitoring circuit includes: a first voltage detection circuit, a second voltage detection circuit, and a status determination circuit;

[0007] Among them, one end of the first voltage detection circuit is used to be connected to one end of the relay, and the other end of the first voltage detection circuit is connected to one end of the second voltage detection circuit through the device to be tested for insulation;

[0008] The other end of the second voltage detection circuit is used to be connected to the other end of the relay;

[0009] The status determination circuit is respectively connected to both ends of the first voltage detection circuit and both ends of the second voltage detection circuit, and is used to collect the first voltage of the first voltage detection circuit and the second voltage of the second voltage detection circuit, and determine the status of the relay based on the pressure difference between the first voltage and the second voltage.

[0010] Optionally, the status determination circuit includes: a pressure difference determination sub-circuit and a status determination sub-circuit;

[0011] The differential pressure determination sub-circuit is respectively connected to both ends of the first voltage detection circuit, both ends of the second voltage detection circuit, and the state determination sub-circuit, and is used to collect the first voltage of the first voltage detection circuit and the second voltage of the second voltage detection circuit, and determine the differential pressure based on the first voltage and the second voltage;

[0012] The state determination sub-circuit is used to determine the state of the relay based on the differential pressure.

[0013] Optionally, the differential pressure determination sub-circuit includes: a voltage acquisition device and a differential pressure determination device;

[0014] The voltage acquisition device is respectively connected to both ends of the first voltage detection circuit, both ends of the second voltage detection circuit, and one end of the differential pressure determination device, and is used to collect the first voltage of the first voltage detection circuit and the second voltage of the second voltage detection circuit;

[0015] The other end of the differential pressure determination device is connected to the state determination sub-circuit, and is used to determine the differential pressure based on the first voltage and the second voltage.

[0016] Optionally, the differential pressure determination device includes a subtractor.

[0017] Optionally, the voltage acquisition device includes: a first voltage collector and a second voltage collector;

[0018] Among them, the input end of the first voltage collector is connected to both ends of the first voltage detection circuit, and the output end of the first voltage collector is connected to one end of the differential pressure determination device;

[0019] The input end of the second voltage collector is connected to both ends of the second voltage detection circuit, and the output end of the second voltage collector is connected to one end of the differential pressure determination device.

[0020] Optionally, the voltage collector includes an operational amplifier, and the voltage collector includes the first voltage collector or the second voltage collector.

[0021] Optionally, the state monitoring circuit further includes: an analog-to-digital conversion circuit;

[0022] Among them, the analog-to-digital conversion circuit is connected in series between the differential pressure determination sub-circuit and the state determination sub-circuit.

[0023] Optionally, the state monitoring circuit further includes: an isolation circuit; the isolation circuit is connected in series between the differential pressure determination sub-circuit and the state determination sub-circuit.

[0024] In the withstand voltage insulation test scenario, the isolation circuit serves as an information transmission medium, which can protect the devices in the state monitoring circuit, thereby ensuring the security of information transmission between devices.

[0025] Optionally, the state monitoring circuit further includes: an analog-to-digital conversion circuit;

[0026] Wherein, the analog-to-digital conversion circuit and the isolation circuit are connected in series between the differential pressure determination sub-circuit and the state determination sub-circuit in sequence.

[0027] Optionally, both the first voltage detection circuit and the second voltage detection circuit are resistors.

[0028] When both the first voltage detection circuit and the second voltage detection circuit are resistors, it does not affect the current value of the entire circuit loop, and at the same time, the state of the relay can be accurately monitored.

[0029] On the other hand, a relay state monitoring system is provided, including: an insulating device under test and at least one state monitoring circuit;

[0030] Wherein, each state monitoring circuit is connected to both ends of the corresponding relay.

[0031] On yet another hand, a withstand voltage test system for insulation is provided, including a withstand voltage tester, at least one relay, and the relay state monitoring system described in the above aspect; the withstand voltage tester is connected to the insulating device under test.

[0032] In summary, the embodiments of the present application provide a relay state monitoring circuit, system, and withstand voltage test system for insulation. Since the first voltage detection circuit and the second voltage detection circuit are respectively connected to both ends of the relay, the first voltage of the first detection circuit is the voltage at one end of the relay, and the second voltage of the second voltage detection circuit is the voltage at the other end of the relay. And since the resistance values of the first voltage detection circuit and the second voltage detection circuit are both greater than the resistance value of the relay, the first voltage detection circuit and the second voltage detection circuit both have a relatively large voltage division. Therefore, the state determination circuit can collect the first voltage and the second voltage. Then, compared with the related art, even when the relay is closed, the differential pressure of the relay can be determined by the collected first voltage and second voltage. Furthermore, based on the differential pressure of the relay, the state of the relay can be effectively monitored. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of a relay state monitoring circuit provided by an embodiment of the present application;

[0034] Figure 2 is a schematic structural diagram of another relay state monitoring circuit provided by an embodiment of the present application;

[0035] Figure 3 is a schematic structural diagram of yet another relay state monitoring circuit provided by an embodiment of the present application;

[0036] Figure 4It is a schematic diagram of the relationship curve between contact impedance and the number of uses provided by an embodiment of the present application;

[0037] Figure 5 It is a schematic structural diagram of a relay status monitoring system provided by an embodiment of the present application;

[0038] Figure 6 It is a schematic structural diagram of an insulation withstand voltage test system provided by an embodiment of the present application. Detailed implementation manners

[0039] Hereinafter, embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, and therefore are only examples and cannot be used to limit the protection scope of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0041] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality" is more than two, unless otherwise specifically defined.

[0042] Referring to "embodiment" herein means that a specific feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0043] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the front and rear associated objects.

[0044] In the description of the embodiments of the present application, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0045] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of the present application.

[0046] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0047] Electrical equipment generates electromagnetic fields during operation. If the electromagnetic fields leak outside the equipment, it will be harmful to the human body. Therefore, in order to ensure the safety performance of electrical equipment, it is necessary to conduct insulation and withstand voltage tests on the electrical equipment. Among them, the electrical equipment may include battery packs, battery cells, generators, transformers, high-voltage switchgear, circuit boards, electronic instruments, motors, frequency converters, air conditioners, washing machines, etc. that require insulation and withstand voltage tests. When the electrical equipment is a battery pack, the insulation and withstand voltage test can be used to test the withstand voltage value of the main positive terminal against the outer shell and the withstand voltage value of the main negative terminal against the outer shell. The principle of insulation and withstand voltage is to utilize the insulation performance of insulating materials to isolate various parts of the electrical equipment and prevent current from flowing inside the equipment, thereby achieving the purpose of protecting the safety performance of the electrical equipment.

[0048] A relay is usually provided in the circuit loop where the electrical equipment is located, and the relay is used to control the on and off of the circuit. If the state of the relay is abnormal, for example, the relay is in a closed state when it should not be closed or has poor contact, it may cause poor contact between the main circuit board where the electrical equipment is located and the high-voltage line. Since a high voltage is output by the withstand voltage tester during the insulation withstand voltage test, the poor contact between the main circuit board and the high-voltage line will form a high potential difference. This high potential difference will cause the current to flow to a path that should not be conducting originally (for example, the current will flow to the tiny gaps of the insulating material or the contaminants on the surface, etc.), resulting in a low insulation resistance value, further causing misjudgment, affecting the accuracy of the insulation withstand voltage test results, and even possibly damaging the test equipment or posing a safety threat to personnel. Therefore, monitoring the state of the relay in advance and ensuring the normal operation of the relay can effectively avoid test abnormalities caused by the above situations, thereby improving the reliability of the insulation withstand voltage test.

[0049] In the related art, one end of a digital-to-analog converter is connected to both ends of the relay, and the other end of the digital-to-analog converter is connected to a controller. The analog-to-digital converter is used to collect the pressure difference of the relay, and the controller is used to determine the state of the relay based on the pressure difference collected by the analog-to-digital converter.

[0050] However, the inventors of the present application found that when the relay is closed, its internal resistance is small, so the pressure difference across the relay will be very small, even close to 0. At this time, the analog-to-digital converter may not be able to collect the pressure difference of the relay, resulting in the inability to effectively monitor the state of the relay.

[0051] The embodiment of the present application provides a state monitoring circuit for a relay. Since the first voltage detection circuit and the second voltage detection circuit are respectively connected to both ends of the relay, the first voltage of the first detection circuit is the voltage at one end of the relay, and the second voltage of the second voltage detection circuit is the voltage at the other end of the relay. And since the resistance values of the first voltage detection circuit and the second voltage detection circuit are both greater than the resistance value of the relay, both the first voltage detection circuit and the second voltage detection circuit divide more voltage, so the state determination circuit can collect the first voltage and the second voltage. Then, compared with the related art, even when the relay is closed, the pressure difference of the relay can be determined through the collected first voltage and second voltage. Furthermore, based on the pressure difference of the relay, the state of the relay can be effectively monitored.

[0052] Figure 1 is a schematic structural diagram of a state monitoring circuit for a relay provided by an embodiment of the present application, as Figure 1 shown, the state monitoring circuit 100 includes: a first voltage detection circuit 10, a second voltage detection circuit 20, and a state determination circuit 30. The resistance values of the first voltage detection circuit 10 and the second voltage detection circuit 20 are both greater than the resistance value of the relay K.

[0053] One end of the first voltage detection circuit 10 is used to connect to one end of the relay K, and the other end of the first voltage detection circuit 10 is connected to one end of the second voltage detection circuit 20 through the insulating device under test 200. The other end of the second voltage detection circuit 20 is used to connect to the other end of the relay K.

[0054] The state determination circuit 30 is respectively connected to both ends of the first voltage detection circuit 10 and both ends of the second voltage detection circuit 20, and is used to collect the first voltage of the first voltage detection circuit 10 and the second voltage of the second voltage detection circuit 20, and determine the state of the relay K based on the pressure difference between the first voltage and the second voltage.

[0055] In the embodiment of the present application, the relay K can be a main positive relay, a main negative relay, a pre-charge relay, an electromagnetic relay, or a pressure relay, etc. The insulating device under test 200 can be a battery pack, a battery cell, a generator, a transformer, a high-voltage switchgear, a circuit board, an electronic instrument, a motor, an inverter, an air conditioner, a washing machine, etc., which need to perform insulation withstand voltage testing. The pressure difference between the first voltage and the second voltage is the pressure difference of the relay K, and the pressure difference of the relay K is generally below the millivolt (mV) level. The state of the relay K can include a closed state or an open state.

[0056] When the relay K is in the closed state, since the first voltage detection circuit 10 and the second voltage detection circuit 20 are respectively connected to both ends of the relay K, the first voltage of the first detection circuit 10 can be used as the voltage at one end of the relay K, and the second voltage of the second voltage detection circuit 20 can be used as the voltage at the other end of the relay K. Therefore, the pressure difference between the first voltage and the second voltage is the pressure difference of the relay K, and the pressure difference of the relay K is generally below the millivolt (mV) level.

[0057] Since the resistance value of the first voltage detection circuit 10 and the resistance value of the second voltage detection circuit 20 are both greater than the resistance value of the relay K, the first voltage detection circuit 10 and the second voltage detection circuit 20 have a larger voltage division. Correspondingly, the pressure difference (i.e., the first voltage) of the first voltage detection circuit 10 and the pressure difference (i.e., the second voltage) on the second voltage detection circuit 20 are both larger. Therefore, the state determination circuit 30 can collect the first voltage of the first voltage detection circuit 10 and can also collect the second voltage of the second voltage detection circuit 20. Then, even when the relay K is closed, the pressure difference of the relay K can be determined by collecting the first voltage of the first voltage detection circuit 10 and the second voltage of the second voltage detection circuit 20.

[0058] In summary, the embodiment of the present application provides a state monitoring circuit for a relay. Since the first voltage detection circuit and the second voltage detection circuit are respectively connected to both ends of the relay, the first voltage of the first detection circuit is the voltage at one end of the relay, and the second voltage of the second voltage detection circuit is the voltage at the other end of the relay. And because the resistance values of the first voltage detection circuit and the second voltage detection circuit are both greater than the resistance value of the relay, the first voltage detection circuit and the second voltage detection circuit both have a relatively large voltage division. Then the state determination circuit can collect the first voltage and the second voltage. Even when the relay is closed, based on the collected first voltage and second voltage, the pressure difference of the relay can be determined, and then the state of the relay can be effectively monitored based on the pressure difference of the relay.

[0059] In addition, the present application only needs to connect the first voltage detection circuit and the second voltage detection circuit to both ends of the relay to realize the monitoring of the state of the relay. This circuit design is simple and the hardware cost is low.

[0060] In some embodiments, since the current in the circuit loop is at the microampere (uA) level, the pressure differences of the first voltage detection circuit 10 and the second voltage detection circuit 20 are both at the millivolt (mV) level, and the pressure difference between the first voltage and the second voltage is also at the mV level. Therefore, the pressure difference threshold is also at the mV level. In some embodiments, the corresponding pressure difference threshold can be set according to the resistance values of the first voltage detection circuit 10 and the second voltage detection circuit 20.

[0061] In some embodiments, when the pressure difference between the first voltage and the second voltage is greater than the pressure difference threshold, the state determination circuit 30 can determine that the state of the relay K is the open state. When the pressure difference between the first voltage and the second voltage is less than or equal to the pressure difference threshold, the state determination circuit 30 can determine that the state of the relay K is the closed state. Among them, the pressure difference threshold is pre-stored in the state determination circuit 30. For example, the pressure difference threshold can be 2 mV.

[0062] Assume that the pressure difference threshold is 2 mV, the first voltage is 6 mV, and the second voltage is 9 mV. Then the pressure difference between the first voltage and the second voltage is 3 mV. Since the pressure difference of 3 mV is greater than the pressure difference threshold of 2 mV, the state determination circuit 30 can determine that the state of the relay K is the open state.

[0063] In some embodiments, the contact impedance of relay K can also be used to determine the state of relay K. The state determination circuit 30 can determine the contact impedance of relay K based on the ratio of the pressure difference to the current in the circuit loop where the device under insulation test is located. The contact impedance of relay K refers to the resistance between the contacts when the contacts of the relay are closed, and the contact impedance affects the performance and reliability of the circuit. When the contact impedance is less than the impedance threshold, the state of relay K is determined to be the closed state; when the contact impedance is greater than or equal to the impedance threshold, the state of relay K is determined to be the open state.

[0064] Among them, when relay K is in the closed state, the contact impedance of its contacts is very small, generally below the milliohm level. The current in the circuit loop is the ratio of the test voltage of the withstand voltage tester to the resistance value in the circuit loop. For example, the test voltage can be 1000V and the resistance value in the circuit loop can be 1000Ω, then the current in the circuit loop is 1A.

[0065] In the insulation withstand voltage test scenario, when the state of relay K is the closed state, the state of relay K is good and the insulation withstand voltage test can be carried out. When the state of relay K is the open state, there will be an empty test phenomenon during the insulation withstand voltage test at this time, which will affect the test results. Therefore, it is necessary to confirm and eliminate the faults and then perform the insulation withstand voltage test again to ensure the reliability of the insulation withstand voltage test.

[0066] Optionally, the voltage detection circuit can be a resistor. The voltage detection circuit refers to the first voltage detection circuit 10 or the second voltage detection circuit 20.

[0067] Assuming that the voltage detection circuit is a resistor, then the voltage detection circuit can be a current-limiting resistor, and the resistance value of the voltage detection circuit can be in the kilohm (KΩ) level or the Ω level. For example, the resistance value of the voltage detection circuit can be 50Ω. Selecting a current-limiting resistor with a better resistance value can improve the accuracy of determining the pressure difference of the relay, and further improve the accuracy of determining the state of the relay.

[0068] In the embodiments of the present application, the first voltage detection circuit 10 and the second voltage detection circuit 20 can be the same component or different components. Assuming that both the first voltage detection circuit 10 and the second voltage detection circuit 20 are resistors, the resistance values of the first voltage detection circuit 10 and the second voltage detection circuit 20 can be the same or different.

[0069] When both the first voltage detection circuit 10 and the second voltage detection circuit 20 are resistors, it does not affect the current value of the entire circuit loop, and at the same time, the state of the relay can be accurately monitored.

[0070] Reference Figure 2, the status determination circuit 30 may include a pressure difference determination sub-circuit 301 and a status determination sub-circuit 302. Among them, the status determination sub-circuit 302 may be a microcontroller unit (MCU).

[0071] The pressure difference determination sub-circuit 301 is respectively connected to both ends of the first voltage detection circuit 10, both ends of the second voltage detection circuit 20, and the status determination sub-circuit 302, and is configured to collect the first voltage of the first voltage detection circuit 10 and the second voltage of the second voltage detection circuit 20, and determine the pressure difference based on the first voltage and the second voltage.

[0072] The status determination sub-circuit 302 is configured to determine the status of the relay K based on the pressure difference.

[0073] Reference Figure 3 , the pressure difference determination sub-circuit 301 may include: a voltage acquisition device 3011 and a pressure difference determination device 3012. Optionally, the pressure difference determination device 3012 may include a subtractor or a differential amplifier.

[0074] The voltage acquisition device 3011 is respectively connected to both ends of the first voltage detection circuit 10, both ends of the second voltage detection circuit 20, and one end of the pressure difference determination device 3012, and is configured to collect the first voltage of the first voltage detection circuit 10 and the second voltage of the second voltage detection circuit 20.

[0075] The other end of the pressure difference determination device 3012 is connected to the status determination sub-circuit 302, and is configured to determine the pressure difference based on the first voltage and the second voltage.

[0076] Reference Figure 3 , the voltage acquisition device 3011 may include a first voltage collector A1 and a second voltage collector A2.

[0077] The voltage collector may be an operational amplifier or a voltmeter, etc. The voltage collector may include the first voltage collector A1 or the second voltage collector A2. In the embodiments of the present application, the first voltage collector A1 and the second voltage collector A2 may be the same component or different components. For example, both the first voltage collector A1 and the second voltage collector A2 may be operational amplifiers.

[0078] Among them, the input end of the first voltage collector A1 is connected to both ends of the first voltage detection circuit 10, and the output end of the first voltage collector A1 is connected to one end of the pressure difference determination device 3012.

[0079] The input end of the second voltage collector A2 is connected to both ends of the second voltage detection circuit 20, and the output end of the second voltage collector A2 is connected to one end of the pressure difference determination device 3012.

[0080] In the embodiment of the present application, when the voltage collector is an operational amplifier, the voltage collector can amplify the collected voltage drop with high gain, which is applicable to voltages below millivolts in the present application. Moreover, the voltage collector can perform differential amplification on the voltages at the front and rear ends of the voltage detection circuit, thereby effectively suppressing interference and noise signals, ensuring the accuracy of the determined voltage drop, and further improving the accuracy of the state monitoring circuit.

[0081] Reference Figure 2 and Figure 3 , the state monitoring circuit 100 may further include: an analog-to-digital conversion circuit 40, and the analog-to-digital conversion circuit 40 may be an analog-to-digital converter (ADC).

[0082] Wherein, the analog-to-digital conversion circuit 40 is connected in series between the pressure difference determination sub-circuit 301 and the state determination sub-circuit 302.

[0083] Reference Figure 3 , the analog-to-digital conversion circuit 40 is connected in series between the pressure difference determination device 3012 and the state determination sub-circuit 302.

[0084] Reference Figure 2 and Figure 3 , the state monitoring circuit 100 may further include: an isolation circuit 50. Optionally, the isolation circuit 50 may be an isolation chip.

[0085] Wherein, the isolation circuit 50 is connected in series between the pressure difference determination sub-circuit 301 and the state determination sub-circuit 302.

[0086] In the embodiment of the present application, the analog-to-digital conversion circuit 40 and the isolation circuit 50 are connected in series between the pressure difference determination sub-circuit 301 and the state determination sub-circuit 302 in sequence.

[0087] Reference Figure 3 , the analog-to-digital conversion circuit 40 and the isolation circuit 50 are connected in series between the pressure difference determination device 3012 and the state determination sub-circuit 302 in sequence.

[0088] One end of the isolation circuit 50 far from the state determination sub-circuit 302 is connected to the high-voltage ground, and one end of the isolation circuit 50 close to the state determination sub-circuit 302 is connected to the low-voltage ground. In the withstand voltage insulation test scenario, the isolation circuit 50, as an information transmission medium, can protect the devices in the state monitoring circuit 100, thereby ensuring the security of information transmission between the devices.

[0089] The service life of a relay refers to the number of times or the time it can operate normally under specified conditions. The service life of a relay is affected by various factors and is usually measured by mechanical life and electrical life. In this case, the electrical life is used to evaluate the service life, and the electrical life refers to the number of times a relay can operate normally when it is energized.

[0090] Among them, the contact impedance is closely related to the contact material. The conductivity, oxidation resistance, contact pressure, surface roughness, and temperature stability of the contact material jointly determine the contact impedance. The contact materials usually include silver, gold, platinum, and tungsten. In this case, the insulation withstand voltage test belongs to high-voltage detection, so a contact material with a relatively high contact impedance and suitable for use in a high-voltage environment will be selected. The magnitudes of the load current and load voltage directly affect contact wear and arc generation. The larger the load, the shorter the life.

[0091] In some embodiments, after obtaining the contact impedance of relay K, the state determination sub-circuit 302 can input the contact impedance into the life determination model of the relay to obtain the service life of the relay output by the life determination model. Among them, the life determination model can be trained using multiple sample contact impedances and multiple sample service lives.

[0092] As the number of uses increases, an oxide layer, sulfide, or other contaminants may form on the contact surface, resulting in an increase in contact resistance. Excessive contact resistance will cause the contacts to heat up, and may even cause the contact material to soften, deform, or weld, shortening the service life of the relay. The relationship curve between contact impedance and the number of uses can be as Figure 4 shown, where the number of uses refers to the number of times the relay has been used. In the embodiments of the present application, the least squares method can be used to fit multiple sets of data to obtain this relationship curve, and this relationship curve can satisfy: , is the number of times used, is the contact impedance, and b are both coefficients. Among them, each set of data can include the contact impedance and the number of times used.

[0093] The state determination sub-circuit 302 can input the contact impedance of relay K into this relationship curve to obtain the number of times the relay has been used output by this relationship curve. Furthermore, the state determination sub-circuit 302 can obtain the service life of relay K by subtracting the number of times used from the total number of times relay K has been used.

[0094] In summary, the embodiment of the present application provides a state monitoring circuit for a relay. Since the first voltage detection circuit and the second voltage detection circuit are respectively connected to both ends of the relay, the first voltage of the first detection circuit is the voltage at one end of the relay, and the second voltage of the second voltage detection circuit is the voltage at the other end of the relay. And since the resistance values of the first voltage detection circuit and the second voltage detection circuit are both greater than the resistance value of the relay, the first voltage detection circuit and the second voltage detection circuit both divide more voltage, so that the state determination circuit can collect the first voltage and the second voltage. Even when the relay is closed, the pressure difference of the relay can be determined through the collected first voltage and second voltage, and then the state of the relay can be effectively monitored based on the pressure difference of the relay.

[0095] The embodiment of the present application provides a state monitoring system for a relay. The state monitoring system may include: an insulating device under test 200 and at least one state monitoring circuit, wherein each state monitoring circuit is connected to both ends of a corresponding relay K.

[0096] Reference Figure 5 , at least one state monitoring circuit may include two state monitoring circuits 100, and the relays corresponding to the two state monitoring circuits 100 may include a main positive relay and a main negative relay.

[0097] Figure 6 is a schematic structural diagram of an insulation withstand voltage test system provided by the embodiment of the present application. As Figure 6 shown, the insulation withstand voltage test system may include a withstand voltage tester 1000, at least one relay K, and a state monitoring system 2000. The withstand voltage tester 1000 is connected to the insulating device under test 200 through the relay.

[0098] Among them, the withstand voltage tester 1000 is used to output a test voltage to test the insulation of the insulating device under test 200. By way of example, the test voltage may be 1000V.

[0099] In the insulation withstand voltage test scenario, when both the first voltage detection circuit 10 and the second voltage detection circuit 20 are resistors, since the resistance value in the circuit loop increases compared with the case where the first voltage detection circuit 10 and the second voltage detection circuit 20 are not provided, the withstand voltage tester 1000 can increase the test voltage according to actual needs to ensure the consistency of the test. For example, in the case where the first voltage detection circuit 10 and the second voltage detection circuit 20 are not provided in the circuit loop, the resistance value in the circuit loop is 1000Ω, and the test voltage of the withstand voltage tester 1000 is 1000V. Assuming that the total resistance values of the first voltage detection circuit 10 and the second voltage detection circuit 20 are 200Ω, then since the resistance value in the circuit loop increases, the withstand voltage tester 1000 can increase the test voltage to 1100V.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A state monitoring circuit for a relay, characterized in that, The state monitoring circuit includes: a first voltage detection circuit, a second voltage detection circuit, and a state determination circuit. The resistance values of the first voltage detection circuit and the second voltage detection circuit are both greater than the resistance value of the relay. Among them, one end of the first voltage detection circuit is used to connect to one end of the relay, and the other end of the first voltage detection circuit is connected to one end of the second voltage detection circuit through an insulating device under test. The other end of the second voltage detection circuit is used to connect to the other end of the relay. The state determination circuit is respectively connected to both ends of the first voltage detection circuit and both ends of the second voltage detection circuit, and is used to collect the first voltage of the first voltage detection circuit and the second voltage of the second voltage detection circuit, and determine the state of the relay based on the voltage difference between the first voltage and the second voltage.

2. The state monitoring circuit of the relay according to claim 1, characterized in that, The state determination circuit includes: a voltage difference determination sub-circuit and a state determination sub-circuit. The voltage difference determination sub-circuit is respectively connected to both ends of the first voltage detection circuit, both ends of the second voltage detection circuit, and the state determination sub-circuit, and is used to collect the first voltage of the first voltage detection circuit and the second voltage of the second voltage detection circuit, and determine the voltage difference based on the first voltage and the second voltage. The state determination sub-circuit is used to determine the state of the relay based on the voltage difference.

3. The state monitoring circuit of the relay according to claim 2, characterized in that The voltage difference determination sub-circuit includes: a voltage acquisition device and a voltage difference determination device. The voltage acquisition device is respectively connected to both ends of the first voltage detection circuit, both ends of the second voltage detection circuit, and one end of the voltage difference determination device, and is used to collect the first voltage of the first voltage detection circuit and the second voltage of the second voltage detection circuit. The other end of the voltage difference determination device is connected to the state determination sub-circuit, and is used to determine the voltage difference based on the first voltage and the second voltage.

4. The state monitoring circuit of the relay according to claim 3, characterized in that, The voltage difference determination device includes a subtractor.

5. The state monitoring circuit of the relay according to claim 3, wherein The voltage acquisition device includes: a first voltage acquirer and a second voltage acquirer. Among them, the input end of the first voltage acquirer is connected to both ends of the first voltage detection circuit, and the output end of the first voltage acquirer is connected to one end of the voltage difference determination device. The input end of the second voltage acquirer is connected to both ends of the second voltage detection circuit, and the output end of the second voltage acquirer is connected to one end of the voltage difference determination device.

6. The state monitoring circuit of the relay according to claim 5, characterized in that, The voltage acquirer includes an operational amplifier, and the voltage acquirer includes the first voltage acquirer or the second voltage acquirer.

7. The state monitoring circuit of the relay according to any one of claims 2 to 6, characterized in that The state monitoring circuit further includes: an analog-to-digital conversion circuit. Among them, the analog-to-digital conversion circuit is connected in series between the voltage difference determination sub-circuit and the state determination sub-circuit.

8. The state monitoring circuit of a relay according to any one of claims 2 to 6, characterized in that The state monitoring circuit further includes: an isolation circuit. The isolation circuit is connected in series between the voltage difference determination sub-circuit and the state determination sub-circuit.

9. The state monitoring circuit of the relay according to claim 8, characterized in that, The state monitoring circuit further includes: an analog-to-digital conversion circuit. Among them, the analog-to-digital conversion circuit and the isolation circuit are connected in series in sequence between the voltage difference determination sub-circuit and the state determination sub-circuit.

10. The state monitoring circuit of a relay according to any one of claims 1 to 6, characterized in that, Both the first voltage detection circuit and the second voltage detection circuit are resistors.

11. A state monitoring system for a relay, characterized in that, Comprising: An insulating device under test and a state monitoring circuit for at least one relay as claimed in any one of claims 1 to 10; Wherein each of the state monitoring circuits is connected to both ends of the corresponding relay.

12. An insulation withstand voltage test system, characterized in that, Comprising a withstand voltage tester, at least one relay and a state monitoring system for the relay as claimed in claim 11; Wherein the withstand voltage tester is connected to the insulating device under test.

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