CN220207745U - High-precision full-automatic resistance measurement circuit - Google Patents
High-precision full-automatic resistance measurement circuit Download PDFInfo
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- CN220207745U CN220207745U CN202321127583.5U CN202321127583U CN220207745U CN 220207745 U CN220207745 U CN 220207745U CN 202321127583 U CN202321127583 U CN 202321127583U CN 220207745 U CN220207745 U CN 220207745U
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- 238000004891 communication Methods 0.000 claims abstract description 17
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Abstract
The utility model relates to the technical field of resistance measurement, in particular to a high-precision full-automatic resistance measurement circuit. The technical proposal comprises: the device comprises a main control circuit, a digital-to-analog conversion circuit, a measurement channel selection circuit, a serial communication display circuit, a power module, a constant current source type resistance measurement circuit, a voltage division type resistance measurement circuit and a bridge voltage division type resistance measurement circuit. According to the high-precision full-automatic resistance measurement circuit, the MCU module of the main control circuit is used for completing automatic measurement of the resistance in a multi-channel selection mode, the internal integrated high-precision A/D converter is used for completing accurate acquisition of resistance measurement data, and the measurement circuits are respectively designed for the resistances in different resistance ranges, so that the accuracy of resistance measurement is ensured, and the main control circuit is used for enabling the resistance measurement process to be concise and efficient.
Description
Technical Field
The utility model relates to the technical field of resistance measurement, in particular to a high-precision full-automatic resistance measurement circuit.
Background
The resistor is one of the electronic components with the highest frequency in the electronic circuit, and is widely applied to the technical field of sensor measurement, wherein a plurality of sensors for measuring physical quantities convert the measured physical quantities into the change of resistance values.
In an electric power system, the rapid and accurate measurement of the direct current resistance of a load is an important content of on-site detection, fault diagnosis and real-time maintenance of electric power equipment. At present, the direct current resistance of a measuring load is mostly divided into a constant voltage source and a constant current source by adopting a resistance-voltage conversion method. In the resistance measurement process, the limitation on the circuit caused by different methods cannot meet the requirements of resistance measurement work in all resistance ranges, so that the measured resistance data is inaccurate, and the operation procedure is slightly complicated.
Disclosure of Invention
The utility model aims to solve the problems in the background technology and provides a high-precision full-automatic resistance measurement circuit.
The technical scheme of the utility model is as follows: a high-precision full-automatic resistance measurement circuit comprises a main control circuit, a digital-to-analog conversion circuit, a measurement channel selection circuit, a serial communication display circuit, a power supply module, a constant current source type resistance measurement circuit, a voltage division type resistance measurement circuit and a bridge voltage division type resistance measurement circuit;
the main control circuit is connected with the communication module, the measurement channel selection circuit and the digital-to-analog conversion circuit, the digital-to-analog conversion circuit is connected with the data interface of the main control circuit and the output end of the resistance measurement circuit, the measurement channel selection circuit is connected with the input end of the measurement circuit and the red and black pen, the serial communication display circuit is connected with the USB and display interfaces and the 485 communication interface, the power module is connected with the power input end of each module circuit, the resistance measurement circuit is connected with the input end of the channel selection circuit and the input end of the acquisition circuit, and the resistance measurement scheme comprises constant current source type, voltage division type and bridge voltage division type;
the main control circuit is used for completing the selection of the measuring circuit for completing the high-precision measurement of the resistance value through the measuring channel selection circuit and the digital-to-analog conversion circuit, the main control circuit is also used for transmitting the processed data to the serial port and the display module through the serial port communication display circuit, the digital-to-analog conversion circuit is used for completing the digital-to-analog conversion of the data and packaging the data to the MCU, the measuring channel selection circuit is used for completing the selection of the measuring circuit for completing the high-precision measurement of the resistance value of the resistance in different resistance value ranges, the resistance measuring circuit is used for completing the measurement of the resistance value of 0.1R to 500M through the constant current source method, the voltage division method and the bridge voltage division method, and the MCU is used for completing the measurement scheme selection of the resistance measuring circuit through controlling the analog switch circuit and the relay circuit.
Preferably, the scheme selection of the resistance measurement circuit is completed on the MCU through an analog switch circuit and a relay circuit.
Preferably, the constant current source type resistance measuring circuit samples the voltage at two ends of the resistance to be measured through the fixed current generated by the constant current source, the voltage at the sampling point is connected to the common mode input end of the amplifier, and the output end of the amplifier is connected to the digital-to-analog conversion circuit, so that the resistance ranging from 0.1R to 50R is measured.
Preferably, the voltage dividing resistor measuring circuit is a fixed voltage, voltage at two ends of the resistor to be measured is sampled through voltage drop generated by the voltage dividing resistor, the voltage at the sampling point is connected to the common mode input end of the amplifier, and the output end of the amplifier is connected to the digital-to-analog conversion circuit, so that the measurement of the resistor with the resistance value ranging from 50R to 10M is completed.
Preferably, after the bridge voltage dividing resistance measuring circuit divides voltage through the bridge, the differential signal is connected with two groups of identical instrument amplifiers, and is connected with an RC filter circuit after one instrument amplifier, so as to filter DC components, keep AC 50HZ, and then be connected with an operational amplifier, wherein one added potentiometer adjusts phase, and the other added potentiometer adjusts amplitude, so that 50HZ waveforms of two paths are consistent, and the two paths can be completely filtered when being connected with a differential amplifier of a later stage, only a DC part is reserved, at the moment, the voltage at the output end of the amplifier is sampled, and the voltage at a sampling point is connected with a digital-analog conversion circuit, so that the measurement of the resistance in the range of 10M to 500M resistance is completed.
Preferably, the main control circuit comprises a low-power-consumption and high-performance processor, and an A/D conversion module with 24-bit precision is integrated in the main control circuit.
Preferably, the MCU transmits the data to the main control panel of the display screen through serial communication.
Compared with the prior art, the utility model has the beneficial effects that: according to the high-precision full-automatic resistance measurement circuit, the MCU module of the main control circuit is used for completing automatic measurement of the resistance in a multi-channel selection mode, the internal integrated high-precision A/D converter is used for completing accurate acquisition of resistance measurement data, and the measurement circuits are respectively designed for the resistances in different resistance ranges, so that the accuracy of resistance measurement is ensured, and the main control circuit is used for enabling the resistance measurement process to be concise and efficient.
Drawings
FIG. 1 is a schematic diagram of a constant current source type resistance measurement circuit of a high-precision full-automatic resistance measurement circuit;
FIG. 2 is a schematic diagram of a voltage dividing resistance measuring circuit of a high-precision fully automatic resistance measuring circuit according to the present utility model;
FIG. 3 is a schematic diagram of a bridge voltage division type resistance measurement circuit of a high-precision full-automatic resistance measurement circuit according to the present utility model;
FIG. 4 is a schematic diagram of a measurement channel selection circuit of a high-precision fully automatic resistance measurement circuit according to the present utility model;
FIG. 5 is a schematic diagram of a digital-to-analog conversion circuit of a high-precision fully automatic resistance measurement circuit according to the present utility model;
FIG. 6 is a schematic diagram of a master control circuit of a high-precision fully automatic resistance measurement circuit according to the present utility model;
fig. 7 is a schematic diagram of a switching power supply circuit of a high-precision fully-automatic resistance measurement circuit according to the present utility model.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments.
Example 1
Referring to fig. 1-7, a high-precision full-automatic resistance measurement circuit comprises a main control circuit, a digital-to-analog conversion circuit, a measurement channel selection circuit, a serial port communication display circuit, a power supply module, a constant current source type resistance measurement circuit, a voltage division type resistance measurement circuit and a bridge voltage division type resistance measurement circuit;
the main control circuit is connected with the communication module, the measurement channel selection circuit and the digital-to-analog conversion circuit, the digital-to-analog conversion circuit is connected with the data interface of the main control circuit and the output end of the resistance measurement circuit, the measurement channel selection circuit is connected with the input end of the measurement circuit and the red and black pen, the serial communication display circuit is connected with the USB and display interfaces and the 485 communication interface, the power module is connected with the power input end of each module circuit, the resistance measurement circuit is connected with the input end of the channel selection circuit and the input end of the acquisition circuit, and the resistance measurement scheme comprises constant current source type, voltage division type and bridge voltage division type;
the main control circuit is used for completing the selection of a resistance measurement scheme and the acquisition and processing of measured data through a measurement channel selection circuit and a digital-to-analog conversion circuit, the main control circuit is also used for transmitting the processed data to a serial port and a display module through a serial port communication display circuit, the digital-to-analog conversion circuit is used for completing the digital-to-analog conversion of the data and packaging the data to an MCU, the measurement channel selection circuit is used for completing the selection of the resistance in different resistance ranges so as to complete the high-precision measurement of the resistance, the high-precision resistance measurement is composed of a constant current source type resistance measurement circuit, a voltage division type resistance measurement circuit and a bridge voltage division type resistance measurement circuit, the resistance measurement circuit is used for completing the measurement of the resistance with the resistance of 0.1R to 500M through a constant current source method, a voltage division method and a bridge voltage division method, in the embodiment, the MCU is used for completing the measurement scheme selection of the resistance measurement circuit through controlling an analog switch circuit and a relay circuit, the scheme selection of the resistance measurement circuit is completed on the MCU through the analog switch circuit and the relay circuit, the main control circuit comprises a low-precision processor, the high-performance integrated circuit is used for transmitting the data to an MCU through a serial port to a display module, and the MCU is used for transmitting the data to an integrated circuit;
as shown in fig. 4, the two schemes of the diagram gate the small resistance measurement diagram, and when the channel selection circuit is measured, the resistors with different resistance ranges are connected into the corresponding resistance measurement circuits through the analog switch and the relay circuit;
as shown in fig. 5, the digital-to-analog conversion circuit reads a certain voltage signal measured by the resistance measurement circuit through the SPI bus;
as shown in fig. 6, the main control circuit is used for completing the selection of the resistance measuring circuit and the analog-to-digital conversion of the voltage signal and sending the resistance value of the measured resistance to the main control board of the display screen;
as shown in fig. 7, the switching power supply circuit provides power for circuits such as a resistance measurement circuit, a CPU and the like, and the voltage is 12V to 5V;
the high-precision full-automatic resistance measurement circuit is applied to high-precision measurement of load resistance so as to conveniently finish detection of electrical equipment.
Example two
Referring to fig. 1, the diagram is a constant current source 20mA measuring small range resistor (0.1R-50R), based on the first embodiment, the constant current source type resistor measuring circuit samples the voltage at two ends of the resistor to be measured through the fixed current generated by the constant current source, the voltage at the sampling point is connected to the common mode input end of the amplifier, the output end of the amplifier is connected to the digital-analog conversion circuit, the measurement of the resistor in the range of 0.1R to 50R is completed, as shown in fig. 1, the constant current source type resistor measuring circuit is suitable for measuring the resistor with small resistance (0.1R-50R), the constant current source type resistor measuring circuit is divided into two paths according to the resistance of the resistor to be measured, and the operational amplifier of each path has different amplification factors. The working principle is that +5V is stabilized to 2.5V by a voltage stabilizing tube, and the positive input end of an amplifier is connected with the positive input end of the amplifier according to I O ＝(V + –V - ) And (1/25k+1/R), calculating current, then connecting the current into a resistor to be measured, amplifying the voltage at two ends of the resistor to be measured through an operational amplifier OP77, then transmitting the amplified voltage to a digital-to-analog converter ADS1262, then transmitting the amplified voltage to a CPU through the digital-to-analog converter, sampling a voltage result through an ADC of the CPU, and calculating the resistance of the resistor to be measured by combining an actual voltage value calculated by the amplification factor and the current value of a constant current source.
Example III
Referring to fig. 2, the analog switch gate is a voltage division type measuring resistor (50R-10M), based on the first embodiment, the voltage division type resistor measuring circuit is a fixed voltage, the voltage at two ends of the resistor to be measured is sampled through the voltage division resistor to generate a voltage drop, the voltage at the sampling point is connected to the common mode input end of the amplifier, and the output end of the amplifier is connected to the digital-analog conversion circuit to finish the measurement of the resistor in the range of 50R to 10M, as shown in fig. 2, the voltage division type resistor measuring circuit is applicable to the resistor with the range of 50R-10M, the voltage division resistance is divided into 4 paths according to the resistance of the resistor to be measured, and the resistance of the voltage division resistors of each path is slightly different. The working principle is that firstly, a proper voltage dividing resistor is selected according to the resistance value of a resistor to be tested, then the voltage dividing resistor and the resistor to be tested are divided by a constant voltage source, a voltage signal is transmitted to a digital-to-analog converter ADS1262 through an operational amplifier TL084 by utilizing the voltage drop generated by the current flowing through the resistor to be tested, then the voltage signal is transmitted to a CPU through the digital-to-analog converter, the voltage result is sampled through the ADC of the CPU, and the resistance value of the resistor to be tested is calculated by combining the amplification factor, the voltage value of the constant voltage source and the resistance value of the voltage dividing resistor.
Example IV
Referring to fig. 3, based on the first embodiment, after the bridge voltage dividing resistance measuring circuit divides the voltage through the bridge, the differential signal is connected to two groups of identical instrument amplifiers, and an RC filter circuit is connected to one instrument amplifier, so as to filter out the direct current component, keep the alternating current 50HZ, and then connect to the operational amplifier, wherein the added potentiometer adjusts the phase and adjusts the amplitude, so that the 50HZ waveforms of the two paths are consistent, and the voltage at the output end of the amplifier is sampled when the voltage is connected to the differential amplifier of the later stage, and the voltage at the sampling point is connected to the digital-analog conversion circuit, so as to finish the measurement of the resistance in the range of 10M to 500M. The working principle of the voltage regulator is that a constant voltage source divides voltage through an electric bridge and then transmits voltages at two ends of a bridge arm to two identical instrument amplifiers I NA128 to obtain two identical voltage signals, wherein one voltage signal isolates direct current components of the voltage signals through an RC filter circuit and adjusts the amplitude and the phase of the voltage signals through an operational amplifier NE5532, so that a voltage signal with only alternating current components is obtained, then the voltage signal and the other voltage signal are connected to the instrument amplifier I NA128 to obtain a voltage signal with only direct current components, then the voltage signal is connected to a digital-analog converter ADS1262 and then transmitted to a CPU through the digital-analog converter, voltage results are sampled through the ADC of the CPU, and the resistance value of a resistor to be measured is calculated by combining the resistance voltage value of the bridge voltage division.
The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art, who is within the scope of the present utility model, should make equivalent substitutions or modifications according to the technical scheme of the present utility model and the inventive concept thereof, and should be covered by the scope of the present utility model.
Claims (7)
1. The high-precision full-automatic resistance measurement circuit is characterized by comprising a main control circuit, a digital-to-analog conversion circuit, a measurement channel selection circuit, a serial communication display circuit, a power supply module, a constant current source resistance measurement circuit, a voltage division resistance measurement circuit and a bridge voltage division resistance measurement circuit;
the main control circuit is connected with the communication module, the measurement channel selection circuit and the digital-to-analog conversion circuit, the digital-to-analog conversion circuit is connected with the data interface of the main control circuit and the output end of the resistance measurement circuit, the measurement channel selection circuit is connected with the input end of the measurement circuit and the red and black pen, the serial communication display circuit is connected with the USB and display interfaces and the 485 communication interface, the power module is connected with the power input end of each module circuit, the resistance measurement circuit is connected with the input end of the channel selection circuit and the input end of the acquisition circuit, and the resistance measurement scheme comprises constant current source type, voltage dividing type and bridge voltage dividing type.
2. The high-precision full-automatic resistance measurement circuit according to claim 1, wherein the scheme selection of the resistance measurement circuit is completed on the MCU through an analog switch circuit and a relay circuit.
3. The high-precision full-automatic resistance measurement circuit according to claim 1, wherein the constant current source type resistance measurement circuit samples voltages at two ends of a resistance to be measured through fixed current generated by the constant current source, the voltages at sampling points are connected to a common-mode input end of an amplifier, and an output end of the amplifier is connected to a digital-to-analog conversion circuit, so that the resistance in the range of 0.1R to 50R resistance is measured.
4. The high-precision full-automatic resistance measurement circuit according to claim 1, wherein the voltage dividing resistance measurement circuit is a fixed voltage, voltage at two ends of a resistor to be measured is sampled through voltage drop generated by the voltage dividing resistor, the voltage at a sampling point is connected to a common-mode input end of an amplifier, and an output end of the amplifier is connected to a digital-to-analog conversion circuit, so that the measurement of the resistor in the 50R-10M resistance range is completed.
5. The high-precision full-automatic resistance measurement circuit according to claim 1, wherein after the bridge voltage division type resistance measurement circuit divides the voltage through the bridge, a differential signal is connected with two groups of identical instrument amplifiers, and is connected with an RC filter circuit after one instrument amplifier, so as to filter out direct current components, keep alternating current 50HZ, and then is connected with an operational amplifier, wherein a potentiometer is added to adjust phase and amplitude, so as to make the 50HZ waveforms of the two paths consistent, the voltage at the output end of the amplifier is connected with a differential amplifier at the later stage and can be completely filtered, only a direct current part is reserved, at this time, the voltage at the sampling point is connected with a digital-analog conversion circuit, and the measurement of the resistance in the range of 10M to 500M resistance value is completed.
6. The high-precision fully automatic resistance measurement circuit according to claim 1, wherein the main control circuit comprises a low-power-consumption high-performance processor, and a 24-bit precision A/D conversion module is integrated in the main control circuit.
7. The high-precision full-automatic resistance measurement circuit according to claim 2, wherein the MCU transmits data to the display screen main control board through serial communication.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321127583.5U CN220207745U (en) | 2023-05-11 | 2023-05-11 | High-precision full-automatic resistance measurement circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321127583.5U CN220207745U (en) | 2023-05-11 | 2023-05-11 | High-precision full-automatic resistance measurement circuit |
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| CN220207745U true CN220207745U (en) | 2023-12-19 |
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| CN202321127583.5U Active CN220207745U (en) | 2023-05-11 | 2023-05-11 | High-precision full-automatic resistance measurement circuit |
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- 2023-05-11 CN CN202321127583.5U patent/CN220207745U/en active Active
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