Relay contact resistance detection device

Abstract

The utility model discloses a relay contact resistance detection device, and relates to the technical field of resistance measurement. The device comprises a microcontroller, an instrument operational amplifier circuit and an analog switch circuit, the instrument operational amplifier circuit comprises an instrument amplifier chip. The analog switch circuit comprises an analog switch chip and an amplification resistor module. The instrument amplifier chip comprises an input unit, an output pin, a positive gain setting pin and a negative gain setting pin; the analog switch chip comprises a control unit, a first common end pin, a second common end pin and a low conduction unit; the input unit is electrically connected with a relay contact, the output pin and the control unit are both electrically connected with the microcontroller, the first common end pin is electrically connected with the positive gain setting pin, the second common end pin is electrically connected with the low-conduction unit, and the low-conduction unit is electrically connected with the negative gain setting pin through the amplification resistor module. Therefore, wide-range relay contact resistance detection can be carried out by adjusting the magnification times.

Description

Technical Field

[0001] The utility model relates to the technical field of resistance measurement, in particular to a relay contact resistance detection device. Background Art

[0002] Relays are widely used in locomotive vehicles and ground electrical equipment of rail transit, and the number is huge. There are more than 100 important key relays in each train, and the failure resistance of relay contacts ranges from 1Ω to 3000Ω. At present, the status inspection of relays usually relies on manual regular inspection and ad hoc inspection during faults, and there is a large difference between the inspection effect and the actual dynamic situation of operation on the main line. Summary of the Utility Model

[0003] In view of this, the purpose of the utility model is to overcome the deficiencies in the prior art and provide a relay contact resistance detection device, which is used to judge whether the current output is saturated according to the amplified voltage signal output by the instrumentation amplifier chip. If saturated, the amplification factor of the instrumentation amplifier chip is switched through a low on-resistance analog switch chip, so as to realize the detection of relay resistance values with a wide range.

[0004] The utility model provides the following technical solutions:

[0005] The utility model provides a relay contact resistance detection device, which comprises a microcontroller, an instrumentation amplifier circuit and an analog switch circuit;

[0006] The instrumentation amplifier circuit comprises an instrumentation amplifier chip, and the analog switch circuit comprises an analog switch chip and an amplification resistance module;

[0007] The instrumentation amplifier chip comprises an input unit, an output pin, a positive gain setting pin and a negative gain setting pin; the analog switch chip comprises a control unit, a first common terminal pin, a second common terminal pin and a low on-resistance unit;

[0008] The input unit is electrically connected to the relay contact, the output pin and the control unit are both electrically connected to the microcontroller, the first common terminal pin is electrically connected to the positive gain setting pin, the second common terminal pin is electrically connected to the low on-resistance unit, and the low on-resistance unit is electrically connected to the negative gain setting pin through the amplification resistance module;

[0009] The instrumentation amplifier chip is used to amplify the voltage signal of the relay contact resistance to obtain an amplified voltage signal; the microcontroller is used to control the analog switch chip to turn on the amplification resistance module according to the amplified voltage signal to adjust the amplification factor of the instrumentation amplifier chip; and calculate the relay resistance according to the adjusted amplification factor and the amplified voltage signal output by the instrumentation amplifier chip with the adjusted amplification factor.

[0010] In one embodiment, the amplification resistance module includes a first amplification resistance, a second amplification resistance, and a third amplification resistance, and the low-conduction unit includes a first normally-open terminal pin, a second normally-open terminal pin, a first normally-closed terminal pin, and a second normally-closed terminal pin;

[0011] The second common terminal pin is electrically connected to the first normally-closed terminal pin. The first normally-open terminal pin is electrically connected to the negative gain setting pin through the first amplification resistance. The second normally-open terminal pin is electrically connected to the negative gain setting pin through the second amplification resistance. The second normally-closed terminal pin is electrically connected to the negative gain setting pin through the third amplification resistance.

[0012] In one embodiment, the input unit includes a positive input pin and a negative input pin, and the instrumentation op-amp circuit further includes an input voltage division module, and the input voltage division module includes a first input voltage division resistance and a second input voltage division resistance;

[0013] The first end of the first input voltage division resistance is electrically connected to the positive input pin. The first end of the second input voltage division resistance is electrically connected to the negative input pin. The second ends of the first input voltage division resistance and the second input voltage division resistance are both electrically connected to the instrumentation op-amp input power supply.

[0014] In one embodiment, the instrumentation op-amp circuit further includes an input filtering module, and the input filtering module includes a first input filtering capacitor, a second input filtering capacitor, and a third input filtering capacitor;

[0015] The first ends of the first input filtering capacitor and the second input filtering capacitor are respectively electrically connected to the upper end of the relay contact and the first end of the first input voltage division resistance;

[0016] The second end of the second input filtering capacitor and the first end of the third input filtering capacitor are respectively electrically connected to the lower end of the relay contact and the first end of the second input voltage division resistance. The second ends of the first input filtering capacitor and the third input filtering capacitor are both grounded.

[0017] In one embodiment, the instrumentation op-amp circuit further includes a detection voltage division module, and the detection voltage division module includes a first detection voltage division resistance and a second detection voltage division resistance;

[0018] The first end of the first detection voltage division resistance is electrically connected to the output pin. The second end of the first detection voltage division resistance is respectively electrically connected to the microcontroller and the first end of the second detection voltage division resistance. The second end of the second detection voltage division resistance is grounded.

[0019] In one embodiment, the instrumentation operational amplifier circuit further includes an output filtering module, and the output filtering module includes a high-frequency filtering unit and a low-pass filtering unit;

[0020] The input end of the high-frequency filtering unit is electrically connected to the first end of the second detection voltage-dividing resistor, the input end of the low-pass filtering unit is electrically connected to the second end of the first detection voltage-dividing resistor, the first output end of the low-pass filtering unit is electrically connected to the microcontroller, and the output end of the high-frequency filtering unit and the second output end of the low-pass filtering unit are both grounded.

[0021] In one embodiment, the high-frequency filtering unit includes a first output filtering capacitor, and the low-pass filtering unit includes a second output filtering capacitor and an output filtering resistor;

[0022] The first end of the first output filtering capacitor is electrically connected to the first end of the second detection voltage-dividing resistor, the first end of the output filtering resistor is electrically connected to the second end of the first detection voltage-dividing resistor, the second end of the output filtering resistor is electrically connected to the microcontroller and the first end of the second output filtering capacitor respectively, and the second ends of the first output filtering capacitor and the second output filtering capacitor are both grounded;

[0023] Wherein, the first end of the first output filtering capacitor is the input end of the high-frequency filtering unit, the second end of the first output filtering capacitor is the output end of the high-frequency filtering unit, the first end of the output filtering resistor is the input end of the low-pass filtering unit, the second end of the output filtering resistor is the first output end of the low-pass filtering unit, and the second end of the second output filtering capacitor is the second output end of the low-pass filtering unit.

[0024] In one embodiment, the instrumentation amplifier chip includes a positive power supply pin and a negative power supply pin, and the analog switch chip further includes a power supply pin;

[0025] The power supply pin is electrically connected to the analog switch power supply, the positive power supply pin is electrically connected to the instrumentation operational amplifier positive power supply, and the negative power supply pin is electrically connected to the instrumentation operational amplifier negative power supply.

[0026] In one embodiment, the instrumentation operational amplifier circuit further includes a first decoupling capacitor and a second decoupling capacitor, and the analog switch circuit further includes a third decoupling capacitor and an energy storage capacitor;

[0027] The positive power supply pin is grounded through the first decoupling capacitor, the instrumentation operational amplifier negative power supply is grounded through the second decoupling capacitor, the power supply pin is electrically connected to the first end of the third decoupling capacitor and the first end of the energy storage capacitor respectively, and the second ends of the third decoupling capacitor and the energy storage capacitor are both grounded.

[0028] In one embodiment, the instrumentation amplifier chip further includes a reference voltage pin, and the analog switch chip further includes a ground pin;

[0029] The reference voltage pin is electrically connected to the instrumentation amplifier input power supply, and the ground pin is grounded.

[0030] The relay contact resistance detection device disclosed by the present utility model includes a microcontroller, an instrumentation amplifier circuit, and an analog switch circuit; the instrumentation amplifier circuit includes an instrumentation amplifier chip, and the analog switch circuit includes an analog switch chip and an amplification resistance module; the instrumentation amplifier chip includes an input unit, an output pin, a positive gain setting pin, and a negative gain setting pin; the analog switch chip includes a control unit, a first common terminal pin, a second common terminal pin, and a low conduction unit; the input unit is electrically connected to the relay contact, the output pin and the control unit are both electrically connected to the microcontroller, the first common terminal pin is electrically connected to the positive gain setting pin, the second common terminal pin is electrically connected to the low conduction unit, and the low conduction unit is electrically connected to the negative gain setting pin through the amplification resistance module; the instrumentation amplifier chip is used to amplify the voltage signal between the upper end and the lower end of the relay contact to obtain an amplified voltage signal; the microcontroller is used to control the analog switch chip to conduct the amplification resistance module according to the amplified voltage signal to adjust the amplification factor of the instrumentation amplifier chip; the microcontroller is further used to calculate the relay resistance according to the adjusted amplification factor and the amplified voltage signal output by the instrumentation amplifier chip with the adjusted amplification factor. In this way, by the microcontroller detecting whether the magnitude of the voltage signal output by the instrumentation amplifier chip matches the amplification factor, if not, the microcontroller controls the analog switch chip to conduct the amplification resistance to adjust the amplification factor of the instrumentation amplifier chip, so as to ensure that the finally output amplified voltage signal is not saturated, thereby accurately calculating the resistance value of the relay contact resistance, and further realizing the detection of the relay contact resistance with a wide range. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the present utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present utility model, and thus should not be regarded as limiting the protection scope of the present utility model. In each drawing, similar components are numbered similarly.

[0032] Figure 1 FIG. 1 shows a circuit schematic diagram of the relay contact resistance detection device proposed by the present utility model;

[0033] Figure 2 FIG. 2 shows a circuit schematic diagram of the input voltage dividing module proposed by the present utility model;

[0034] Figure 3 shows a circuit schematic diagram of the input filter module proposed by the present utility model;

[0035] Figure 4 shows a circuit schematic diagram of the detection voltage division module proposed by the present utility model;

[0036] Figure 5 shows a circuit schematic diagram of the output filter module proposed by the present utility model;

[0037] Figure 6 shows a circuit schematic diagram of the analog switch circuit proposed by the present utility model.

[0038] Description of the drawings: 100 - microcontroller; 200 - instrumentation operational amplifier circuit; 201 - instrumentation amplifier chip; 202 - input voltage division module; 203 - input filter module; 204 - detection voltage division module; 205 - output filter module; 2051 - high - frequency filter unit; 2052 - low - pass filter unit; 300 - analog switch circuit; 301 - analog switch chip; 302 - amplification resistance module; 400 - relay contact resistance. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments.

[0040] Generally, the components of the embodiments of the present utility model described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present utility model provided in the drawings is not intended to limit the scope of the claimed present utility model, but merely represents the selected embodiments of the present utility model. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative efforts belong to the scope of protection of the present utility model.

[0041] In the following text, the terms "including", "having" and their cognates that can be used in various embodiments of the present utility model are only intended to represent specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0042] In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present utility model pertain. The terms (such as those defined in a commonly used dictionary) will be interpreted as having the same meaning as their contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in various embodiments of the present utility model.

[0044] Embodiment 1

[0045] An embodiment of the present disclosure provides a relay contact resistance detection device, which is used to determine whether the current output is saturated according to the amplified voltage signal output by an instrumentation amplifier chip. If it is saturated, the amplification factor of the instrumentation amplifier chip is switched through a low-conduction-resistance analog switch chip, so as to realize the detection of the relay resistance value with a wide range.

[0046] Please refer to Figure 1 , the relay contact resistance detection device includes a microcontroller 100, an instrumentation operational amplifier circuit 200 and an analog switch circuit 300; the instrumentation operational amplifier circuit 200 includes an instrumentation amplifier chip 201, and the analog switch circuit 300 includes an analog switch chip 301 and an amplification resistance module 302; the instrumentation amplifier chip 201 includes an input unit, an output pin OUT, a positive gain setting pin RG+, and a negative gain setting pin RG-; the analog switch chip 301 includes a control unit, a first common terminal pin COM1, a second common terminal pin COM2, and a low-conduction unit; the input unit is electrically connected to the relay contact resistance 400, the output pin OUT and the control unit are both electrically connected to the microcontroller 100, the first common terminal pin COM1 is electrically connected to the positive gain setting pin RG+, the second common terminal pin COM2 is electrically connected to the low-conduction unit, and the low-conduction unit is electrically connected to the negative gain setting pin RG- through the amplification resistance module 302; the instrumentation amplifier chip 201 is used to amplify the voltage signal of the relay contact resistance to obtain an amplified voltage signal; the microcontroller 100 is used to control the analog switch chip 301 to conduct the amplification resistance module 302 according to the amplified voltage signal to adjust the amplification factor of the instrumentation amplifier chip 201; and calculate the relay resistance according to the adjusted amplification factor and the amplified voltage signal output by the instrumentation amplifier chip 201 after the amplification factor is adjusted.

[0047] In this embodiment, the pins of the input unit in the instrumentation amplifier chip 201 respectively acquire the differential voltage signal between the upper end RS_P_IN and the lower end RS_N_IN of the relay contact, amplify it according to the initial amplification factor, and output the amplified voltage signal ADC1 to the microcontroller (MCU) 100 through the output pin OUT.

[0048] Further, the microcontroller 100 outputs control signals AGP1 and AGP2 according to the amplified voltage signal ADC1, and the pins of the control unit in the analog switch chip 301 acquire the control signals AGP1 and AGP2.

[0049] Exemplarily, when the microcontroller 100 detects that the amplified voltage signal ADC1 reaches 95% of the maximum value of the detection range of the microcontroller 100, and it can be known that the voltage is saturated at this time through the corresponding ADC (analog-to-digital converter) value, so it is necessary to reduce the amplification factor of the instrumentation amplifier chip 201 by one level through the control signals AGP1 and AGP2. For example, please refer to Table 1. Currently, the amplification factor of the instrumentation amplifier chip 201 is 991 times, the control signal AGP1 is 0, and the control signal AGP2 is 1. If it is necessary to reduce one level and make the amplification factor of the instrumentation amplifier chip 201 become 101 times, then the control signal AGP1 needs to be set to 1 and the control signal AGP2 needs to be set to 0.

[0050] It should be noted that when the ADC value of the current amplified voltage signal ADC1 is greater than the target setting, it can be known that the output is saturated at this time. This target setting value is related to the operational amplifier parameters.

[0051] Table 1: Corresponding relationship between control signals and amplification factors

[0052] AGP1 AGP2 Magnification factor 0 0 991 0 1 991 1 0 101 1 1 11

[0053] Further, the analog switch chip 301 determines the conduction of the first common terminal pin COM1 and the second common terminal pin COM2 with the low-conduction unit in the analog switch chip 301 according to the control signals AGP1 and AGP2, and then controls the conduction of the amplification resistor module 302.

[0054] Further, after the amplification resistor module 302 conducts correspondingly, the amplification factor of the instrumentation amplifier chip 201 can be changed through the positive gain setting pin RG+ and the negative gain setting pin RG-. At this time, the instrumentation amplifier chip 201 with the adjusted amplification factor amplifies the voltage signal, and transmits the amplified voltage signal to the microcontroller 100. The microcontroller 100 calculates the relay resistance according to the adjusted amplification factor and the amplified voltage signal output by the instrumentation amplifier chip 201 with the adjusted amplification factor.

[0055] It should be noted that the microcontroller 100 analyzes the voltage signal output by the instrumentation amplifier chip 201. When the amplification factor of the instrumentation amplifier chip 201 does not match the magnitude of the voltage signal, it can be known that the voltage signal is saturated at this time. Therefore, the microcontroller 100 needs to control the low-conduction amplification resistance module 302 of the analog switch chip 301 to adjust the amplification factor of the instrumentation amplifier chip 201, so that the voltage signal output by the adjusted instrumentation amplifier chip 201 is not saturated, and then accurately calculate the relay contact resistance value to achieve wide-range detection of the relay contact resistance value.

[0056] In a specific embodiment, the amplification resistance module 302 includes a first amplification resistance R1, a second amplification resistance R2, and a third amplification resistance R3, and the low-conduction unit includes a first normally open terminal pin NC1, a second normally open terminal pin NC2, a first normally closed terminal pin NO1, and a second normally closed terminal pin NO2; the second common terminal pin COM1 is electrically connected to the first normally closed terminal pin NO1, the first normally open terminal pin NO1 is electrically connected to the negative gain setting pin RG- through the first amplification resistance R1, the second normally open terminal pin NO2 is electrically connected to the negative gain setting pin RG- through the second amplification resistance R2, and the second normally closed terminal pin NC2 is electrically connected to the negative gain setting pin RG- through the third amplification resistance R3.

[0057] In this embodiment, the analog switch chip 301 determines whether the first common terminal pin COM1 is conducted with the first normally open terminal pin NO1 or the first normally closed terminal pin NC1 according to the control signal AGP1, and determines whether the second common terminal pin COM2 is conducted with the second normally open terminal pin NO2 or the second normally closed terminal pin NC2 according to the control signal AGP2.

[0058] Exemplarily, if the control signal AGP1 is 0 and the control signal AGP2 is 1, then the first common terminal pin COM1 is conducted with the first normally closed terminal pin NC1, and the second common terminal pin COM2 is conducted with the second normally open terminal pin NO2.

[0059] When the first normally open terminal pin NO1 is turned on, the corresponding first amplification resistor R1 is turned on, thereby adjusting the resistor network between the positive gain setting pin RG+ and the negative gain setting pin RG- according to the first amplification resistor R1; when the second normally open terminal pin NO2 is turned on, the corresponding second amplification resistor R2 is turned on, thereby adjusting the resistor network between the positive gain setting pin RG+ and the negative gain setting pin RG- according to the second amplification resistor R2; when the second normally closed terminal pin NC2 is turned on, the corresponding third amplification resistor R3 is turned on, thereby adjusting the resistor network between the positive gain setting pin RG+ and the negative gain setting pin RG- according to the third amplification resistor R3. Among them, the models of the first amplification resistor R1, the second amplification resistor R2, and the third amplification resistor R3 are different. For example, the parameters of the first amplification resistor R1 can be "49.9R ± 0.5% 0805", the parameters of the second amplification resistor R2 can be "4.99K ± 1% 0805", and the parameters of the third amplification resistor R3 can be "499R ± 1% 0805". In this way, the amplification factor of the instrumentation amplifier chip 201 is adjusted by turning on different models of amplification resistors.

[0060] Please refer to Figure 2 , in a specific embodiment, the input unit includes a positive input pin + and a negative input pin -, and the instrumentation operational amplifier circuit 200 further includes an input voltage dividing module 202. The input voltage dividing module 202 includes a first input voltage dividing resistor R4 and a second input voltage dividing resistor R5; the first end of the first input voltage dividing resistor R4 is electrically connected to the positive input pin +, the first end of the second input voltage dividing resistor R5 is electrically connected to the negative input pin -, and the second ends of the first input voltage dividing resistor R4 and the second input voltage dividing resistor R5 are both electrically connected to the instrumentation operational amplifier input power supply.

[0061] In this embodiment, the instrumentation operational amplifier input power supply (2.48V) provides the instrumentation operational amplifier input parameter voltage to the instrumentation amplifier chip 201 through the positive input pin + and the negative input pin -. At the same time, by connecting the first input voltage dividing resistor R4 in series between the instrumentation operational amplifier input power supply and the positive input pin +, and connecting the second input voltage dividing resistor R5 in series between the instrumentation operational amplifier input power supply and the negative input pin -, the instrumentation operational amplifier input parameter voltage can be stepped down to the input range of the instrumentation amplifier chip 201, thereby protecting the instrumentation amplifier chip 201.

[0062] Please refer to Figure 3, in a specific embodiment, the instrumentation op-amp circuit 200 further includes an input filtering module 203, and the input filtering module 203 includes a first input filtering capacitor C1, a second input filtering capacitor C2, and a third input filtering capacitor C3; the first ends of the first input filtering capacitor C1 and the second input filtering capacitor C2 are respectively electrically connected to the upper end of the relay contact RS_P_IN and the first end of the first input voltage-dividing resistor R4; the second ends of the second input filtering capacitor C2 and the first ends of the third input filtering capacitor C3 are respectively electrically connected to the lower end of the relay contact RS_N_IN and the first end of the second input voltage-dividing resistor R5, and the second ends of the first input filtering capacitor C1 and the third input filtering capacitor C3 are both grounded.

[0063] In this embodiment, the first input filtering capacitor C1, the second input filtering capacitor C2, and the third input filtering capacitor C3 can filter out some input interference, thereby reducing the influence on the output voltage signal of the instrumentation amplifier chip 201.

[0064] Please refer to Figure 4 , in a specific embodiment, the instrumentation op-amp circuit 200 further includes a detection voltage-dividing module 204, and the detection voltage-dividing module 204 includes a first detection voltage-dividing resistor R6 and a second detection voltage-dividing resistor R7; the first end of the first detection voltage-dividing resistor R6 is electrically connected to the output pin OUT, the second end of the first detection voltage-dividing resistor R6 is respectively electrically connected to the microcontroller 100 and the first end of the second detection voltage-dividing resistor R7, and the second end of the second detection voltage-dividing resistor R7 is grounded.

[0065] In this embodiment, when the output pin OUT of the instrumentation amplifier chip 201 outputs an amplified voltage signal ADC1, the amplified voltage signal ADC1 is voltage-divided by the first detection voltage-dividing resistor R6 and the second detection voltage-dividing resistor R7 to ensure that the voltage signal obtained by the microcontroller 100 is within the detection range of the microcontroller 100.

[0066] Please refer to Figure 5 , in a specific embodiment, the instrumentation op-amp circuit 200 further includes an output filtering module 205, and the output filtering module 205 includes a high-frequency filtering unit 2051 and a low-pass filtering unit 2052; the input end of the high-frequency filtering unit 2051 is electrically connected to the first end of the second detection voltage-dividing resistor R7, the input end of the low-pass filtering unit 2052 is electrically connected to the second end of the first detection voltage-dividing resistor R6, the first output end of the low-pass filtering unit 2052 is electrically connected to the microcontroller 100, and the output end of the high-frequency filtering unit 2051 and the second output end of the low-pass filtering unit 2052 are both grounded.

[0067] In this embodiment, the amplified voltage signal ADC1 output from the output pin OUT is filtered by the high-frequency filtering unit 2051 and the low-pass filtering unit 2052. Among them, the high-frequency signal interference in the amplified voltage signal ADC1 directly goes to the ground through the high-frequency filtering unit 2051 and the low-pass filtering unit 2052, thereby improving the quality and stability of signal transmission.

[0068] In a specific embodiment, the high-frequency filtering unit 2051 includes a first output filtering capacitor C4, and the low-pass filtering unit 2052 includes a second output filtering capacitor C5 and an output filtering resistor R8; the first end of the first output filtering capacitor C4 is electrically connected to the first end of the second detection voltage-dividing resistor R7, the first end of the output filtering resistor R8 is electrically connected to the second end of the first detection voltage-dividing resistor R6, the second end of the output filtering resistor R8 is respectively electrically connected to the microcontroller 100 and the first end of the second output filtering capacitor C5, and the second ends of the first output filtering capacitor C4 and the second output filtering capacitor C5 are both grounded; wherein, the first end of the first output filtering capacitor C4 is the input end of the high-frequency filtering unit 2051, the second end of the first output filtering capacitor C4 is the output end of the high-frequency filtering unit 2051, the first end of the output filtering resistor R8 is the input end of the low-pass filtering unit 2052, the second end of the output filtering resistor R8 is the first output end of the low-pass filtering unit 2052, and the second end of the second output filtering capacitor C5 is the second output end of the low-pass filtering unit 2052.

[0069] In this embodiment, the high-frequency filtering unit 2051 includes a first output filtering capacitor C4. The first end of the first output filtering capacitor C4 serves as the input end of the high-frequency filtering unit 2051, and the second end of the first output filtering capacitor C4 serves as the output end of the high-frequency filtering unit 2051. The high-frequency signal in the amplified voltage signal ADC1 directly goes from the first output filtering capacitor C4 to the ground. The low-pass filtering unit 2052 includes a second output filtering capacitor C5 and an output filtering resistor R8. The high-frequency noise in the amplified voltage signal ADC1 directly goes to the ground via the output filtering resistor R8 and the second output filtering capacitor C5, thereby realizing the filtering of the output signal.

[0070] Please refer to Figure 5 and Figure 6 , in a specific embodiment, the instrumentation amplifier chip 201 includes a positive power supply pin V1+ and a negative power supply pin V1-, and the analog switch chip 301 further includes a power supply pin V2+; the power supply pin V2+ is electrically connected to the analog switch power supply, the positive power supply pin V1+ is electrically connected to the instrumentation operational amplifier positive power supply, and the negative power supply pin V1- is electrically connected to the instrumentation operational amplifier negative power supply.

[0071] In this embodiment, the positive power supply (12V+) and negative power supply (12V-) of the instrumentation op-amp supply operating voltage to the instrumentation amplifier chip 201 through the positive power supply pin V1+ and negative power supply pin V1- respectively. The analog switch power supply (5V+) is used to supply operating voltage to the analog switch chip 301.

[0072] In a specific embodiment, the instrumentation op-amp circuit 200 further includes a first decoupling capacitor C6 and a second decoupling capacitor C7, and the analog switch circuit 300 further includes a third decoupling capacitor C8 and an energy storage capacitor C9; the positive power supply pin V1+ is grounded through the first decoupling capacitor C6, the negative power supply of the instrumentation op-amp is grounded through the second decoupling capacitor C7, the power supply pin is electrically connected to the first ends of the third decoupling capacitor C8 and the energy storage capacitor C9 respectively, and the second ends of the third decoupling capacitor C8 and the energy storage capacitor C9 are both grounded.

[0073] In this embodiment, the first decoupling capacitor C6 can be used to reduce the interference of the positive power supply noise of the instrumentation op-amp on the instrumentation op-amp circuit 200, the second decoupling capacitor C7 can be used to reduce the interference of the negative power supply noise of the instrumentation op-amp on the instrumentation op-amp circuit 200, the third decoupling capacitor C8 can be used to reduce the interference of the analog switch power supply on the analog switch circuit 300, and the energy storage capacitor C9 can be used to maintain the stability of the analog switch power supply.

[0074] In a specific embodiment, the instrumentation amplifier chip 201 further includes a reference voltage pin REF, and the analog switch chip 301 further includes a ground pin GND; the reference voltage pin REF is electrically connected to the input power supply of the instrumentation op-amp, and the ground pin GND is grounded.

[0075] In this embodiment, the electrical connection between the reference voltage pin REF and the input power supply of the instrumentation op-amp is mainly used to provide an output reference voltage; while the ground pin GND is responsible for providing a zero-potential reference point to improve the stability and signal quality of the circuit. The two cooperate to ensure the normal operation and performance optimization of the circuit.

[0076] The relay contact resistance detection device proposed in this embodiment includes a microcontroller, an instrumentation amplifier circuit, and an analog switch circuit; the instrumentation amplifier circuit includes an instrumentation amplifier chip, and the analog switch circuit includes an analog switch chip and an amplification resistance module; the instrumentation amplifier chip includes an input unit, an output pin, a positive gain setting pin, and a negative gain setting pin; the analog switch chip includes a control unit, a first common terminal pin, a second common terminal pin, and a low conduction unit; the input unit is electrically connected to the relay contact, the output pin and the control unit are both electrically connected to the microcontroller, the first common terminal pin is electrically connected to the positive gain setting pin, the second common terminal pin is electrically connected to the low conduction unit, and the low conduction unit is electrically connected to the negative gain setting pin through the amplification resistance module; the instrumentation amplifier chip is used to amplify the voltage signal between the upper end and the lower end of the relay contact to obtain an amplified voltage signal; the microcontroller is used to control the analog switch chip to conduct the amplification resistance module according to the amplified voltage signal to adjust the amplification factor of the instrumentation amplifier chip; and calculate the relay resistance according to the adjusted amplification factor and the amplified voltage signal output by the instrumentation amplifier chip after the amplification factor is adjusted. In this way, by detecting whether the magnitude of the voltage signal output by the instrumentation amplifier chip matches the amplification factor by the microcontroller, if not, the microcontroller controls the analog switch chip to conduct the amplification resistance to adjust the amplification factor of the instrumentation amplifier chip, so that the finally output amplified voltage signal is not saturated, thereby accurately calculating the resistance value of the relay contact, and further realizing the detection of the relay contact resistance with a wide range.

[0077] In all the examples shown and described here, any specific value should be construed as merely exemplary, not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0078] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0079] The above-described embodiments merely represent several implementation manners of the present utility model. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present utility model. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model.

Claims

1. A relay contact resistance detection device, characterized in that: The device comprises a microcontroller, an instrument operational amplifier circuit and an analog switch circuit; the instrument operational amplifier circuit comprises an instrument amplifier chip, and the analog switch circuit comprises an analog switch chip and an amplifying resistor module; The instrument amplifier chip includes an input unit, an output pin, a positive gain setting pin and a negative gain setting pin; the analog switch chip includes a control unit, a first common terminal pin, a second common terminal pin and a low conduction unit; The input unit is electrically connected to the relay contact, the output pin and the control unit are both electrically connected to the microcontroller, the first common terminal pin is electrically connected to the positive gain setting pin, the second common terminal pin is electrically connected to the low conduction unit, and the low conduction unit is electrically connected to the negative gain setting pin through the amplifying resistor module; The instrument amplifier chip is used to amplify the voltage signal of the relay contact resistance to obtain an amplified voltage signal; The microcontroller is used to control the analog switch chip to turn on the amplifying resistance module according to the amplified voltage signal, so as to adjust the amplification factor of the instrument amplifier chip; The relay resistance is calculated according to the adjusted gain and the amplified voltage signal output by the instrument amplifier chip after the gain is adjusted.

2. The relay contact resistance detection device according to claim 1, characterized in that: The amplifying resistor module includes a first amplifying resistor, a second amplifying resistor and a third amplifying resistor, and the low conduction unit includes a first normally open end pin, a second normally open end pin, a first normally closed end pin and a second normally closed end pin; The second common end pin is electrically connected to the first normally closed end pin, the first normally open end pin is electrically connected to the negative gain setting pin through the first amplifying resistor, the second normally open end pin is electrically connected to the negative gain setting pin through the second amplifying resistor, and the second normally closed end pin is electrically connected to the negative gain setting pin through the third amplifying resistor.

3. The relay contact resistance detection device according to claim 1, characterized in that: The input unit includes a positive input pin and a negative input pin, the instrument amplifier circuit also includes an input voltage divider module, and the input voltage divider module includes a first input voltage divider resistor and a second input voltage divider resistor; The first end of the first input voltage divider resistor is electrically connected to the positive input pin, the first end of the second input voltage divider resistor is electrically connected to the negative input pin, and the second end of the first input voltage divider resistor and the second end of the second input voltage divider resistor are both electrically connected to the instrumentation amplifier input power supply.

4. The relay contact resistance detection device according to claim 3, characterized in that: The instrument amplifier circuit further includes an input filter module, and the input filter module includes a first input filter capacitor, a second input filter capacitor and a third input filter capacitor; The first end of the first input filter capacitor and the first end of the second input filter capacitor are electrically connected to the upper end of the relay contact and the first end of the first input voltage-dividing resistor respectively; The second end of the second input filter capacitor and the first end of the third input filter capacitor are electrically connected to the lower end of the relay contact and the first end of the second input voltage divider resistor respectively, and the second end of the first input filter capacitor and the second end of the third input filter capacitor are grounded.

5. The relay contact resistance detection device according to claim 1, characterized in that: The instrument amplifier circuit further includes a detection voltage division module, and the detection voltage division module includes a first detection voltage division resistor and a second detection voltage division resistor; The first end of the first detection voltage-dividing resistor is electrically connected to the output pin, the second end of the first detection voltage-dividing resistor is electrically connected to the microcontroller and the first end of the second detection voltage-dividing resistor respectively, and the second end of the second detection voltage-dividing resistor is grounded.

6. The relay contact resistance detection device according to claim 5, characterized in that: The instrument amplifier circuit further includes an output filter module, and the output filter module includes a high-frequency filter unit and a low-pass filter unit; The input end of the high-frequency filtering unit is electrically connected to the first end of the second detection voltage-dividing resistor, the input end of the low-pass filtering unit is electrically connected to the second end of the first detection voltage-dividing resistor, the first output end of the low-pass filtering unit is electrically connected to the microcontroller, and the output end of the high-frequency filtering unit and the second output end of the low-pass filtering unit are both grounded.

7. The relay contact resistance detection device according to claim 6, characterized in that: The high-frequency filtering unit includes a first output filtering capacitor, and the low-pass filtering unit includes a second output filtering capacitor and an output filtering resistor; The first end of the first output filter capacitor is electrically connected to the first end of the second detection voltage-dividing resistor, the first end of the output filter resistor is electrically connected to the second end of the first detection voltage-dividing resistor, the second end of the output filter resistor is electrically connected to the microcontroller and the first end of the second output filter capacitor respectively, and the second end of the first output filter capacitor and the second end of the second output filter capacitor are both grounded; Among them, the first end of the first output filter capacitor is the input end of the high-frequency filter unit, the second end of the first output filter capacitor is the output end of the high-frequency filter unit, the first end of the output filter resistor is the input end of the low-pass filter unit, the second end of the output filter resistor is the first output end of the low-pass filter unit, and the second end of the second output filter capacitor is the second output end of the low-pass filter unit.

8. The relay contact resistance detection device according to claim 1, characterized in that: The instrument amplifier chip includes a positive power pin and a negative power pin, and the analog switch chip also includes a power pin; The power pin is electrically connected to the analog switch power supply, the positive power pin is electrically connected to the instrument amplifier positive power supply, and the negative power pin is electrically connected to the instrument amplifier negative power supply.

9. The relay contact resistance detection device according to claim 8, characterized in that: The instrument amplifier circuit further includes a first decoupling capacitor and a second decoupling capacitor, and the analog switch circuit further includes a third decoupling capacitor and an energy storage capacitor; The positive power supply pin is grounded through the first decoupling capacitor, the negative power supply of the instrument amplifier is grounded through the second decoupling capacitor, the power supply pin is electrically connected to the first end of the third decoupling capacitor and the first end of the energy storage capacitor respectively, and the second end of the third decoupling capacitor and the second end of the energy storage capacitor are both grounded.

10. The relay contact resistance detection device according to claim 3, characterized in that: The instrument amplifier chip further includes a reference voltage pin, and the analog switch chip further includes a ground pin; The reference voltage pin is electrically connected to the instrument amplifier input power supply, and the ground pin is grounded.

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