CN215340044U - Direct current analog quantity sampling circuit - Google Patents
Direct current analog quantity sampling circuit Download PDFInfo
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- CN215340044U CN215340044U CN202120829119.5U CN202120829119U CN215340044U CN 215340044 U CN215340044 U CN 215340044U CN 202120829119 U CN202120829119 U CN 202120829119U CN 215340044 U CN215340044 U CN 215340044U
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Abstract
The utility model provides a direct current analog quantity sampling circuit which comprises a direct current analog quantity sampling unit, a main control unit and a power supply unit, wherein the direct current analog quantity sampling unit and the main control unit are in information interaction through an SPI (serial peripheral interface) bus, the direct current analog quantity sampling unit is used for collecting direct current analog quantity signals and outputting corresponding digital signals to the main control unit, the direct current analog quantity sampling unit comprises an analog quantity signal source, an analog-to-digital conversion module and a working power supply for providing power supply, the input of the analog quantity signal source receives the direct current analog quantity signals, the output of the analog quantity signal source inputs pseudo-differential signals to the analog-to-digital conversion module, and the output of the analog-to-digital conversion module inputs corresponding digital signals to the main control unit. The utility model can realize the measurement functions of high precision, high anti-interference and wide range of direct current analog quantity, and ensures the accuracy and stability of sampling precision, thereby improving the competitiveness of products and having market popularization advantage.
Description
Technical Field
The utility model relates to the technical field of analog signal processing, in particular to a direct current analog quantity sampling circuit.
Background
With the steady development of the intelligent power grid, the intelligent power distribution automatic terminal is gradually applied to the power system; the terminal can collect and send direct current quantity according to the functional requirements of a document DL/T721 and 2013 distribution automation remote terminal, and the use requirements of DC24V/DC48V/DC110V/DC220V and the like are combined with direct current sampling in practical engineering application.
The direct current analog quantity sampling is a very important measurement part in the power distribution terminal. In order to save cost during design, some circuit acquisition modes only adopt a simple internal AD conversion channel integrated by matching resistor voltage division with a single ARM chip; however, in order to reduce the manufacturing cost, the single ARM chip mostly has only 10 bits or 12 bits of AD sampling resolution, and the linearity of the resistor voltage division mode is poor, so that the requirement of high-precision sampling cannot be met.
In addition, a sampling circuit with feedback mode point-by-point correction is designed by adopting a voltage reference chip TL431, the sampling precision of the method is improved, but a hardware circuit is relatively complex and a software algorithm is complex.
SUMMERY OF THE UTILITY MODEL
The utility model mainly aims to provide a direct current analog quantity sampling circuit with high precision, high interference resistance and wide range.
In order to achieve the above main object, the present invention provides a dc analog sampling circuit, including: the direct current analog quantity sampling unit is used for acquiring a direct current analog quantity signal and outputting a corresponding digital signal to the main control unit; the direct current analog quantity sampling unit comprises an analog quantity signal source, an analog-to-digital conversion module and a working power supply for providing power supply, wherein the input of the analog quantity signal source receives a direct current analog quantity signal, the output of the analog quantity signal source inputs a pseudo differential signal to the analog-to-digital conversion module, and the output of the analog-to-digital conversion module inputs a corresponding digital signal to the main control unit; the main control unit comprises a central processing module, a display module and a communication module, and transmits a direct-current voltage sampling value to the power master station through the communication module and displays the direct-current voltage sampling value in real time through the display module.
In a further aspect, the analog-to-digital conversion module includes an AD conversion chip, the analog signal source inputs a pseudo differential signal to ports V1P and V2P of the AD conversion chip, generates a digital signal proportional to the level of the input pseudo differential signal by the AD conversion chip, and transmits the digital signal to the main control unit by the SPI bus.
In a further scheme, the analog quantity signal source is composed of at least two loops of direct current measuring channels, and each loop of direct current measuring channel comprises 1 piezoresistor, 4 divider resistors, 1 sampling resistor and 4 high-speed diodes.
In a further scheme, the working power supply comprises an isolation power supply circuit and a linear voltage stabilizing circuit, the isolation power supply circuit is connected with a power supply and outputs a 5V power supply signal to the linear voltage stabilizing circuit through a filter capacitor, and the linear voltage stabilizing circuit outputs a 3.3V power supply signal to the AD conversion chip.
In a further scheme, the power supply unit comprises an input port anti-interference module, a power voltage reduction module and a linear voltage stabilizer, the input port anti-interference module is connected with the power voltage reduction module, the power voltage reduction module is connected with the linear voltage stabilizer, and a positive electrode port and a negative electrode port input protection module are further connected to the input port anti-interference module.
In a further scheme, the input port anti-interference module comprises a differential mode piezoresistor RT3, a common mode piezoresistor RT1, RT2, a six-hole magnetic bead inductor FB1, an FB2, a common mode inductor LL1, a safety capacitor CL1, and Y capacitors CY1-CY 7; the positive and negative electrode port input protection module comprises a diode V1, the negative electrode of the diode V1 is connected with one end of the six-hole magnetic bead inductor FB1, and the positive electrode of the diode V1 is connected with the power input end and one end of the differential mode piezoresistor RT 3.
In a further scheme, the power voltage reduction module comprises an AC-DC power module or a DC-DC power module, the AC-DC power module or the DC-DC power module outputs a 24V power signal and a 5V power signal, and the 5V power signal is converted into a 3.3V power signal by the linear regulator and then output.
In a further scheme, the display module is provided with a dot-matrix liquid crystal display and 10 patch tact switches connected with the dot-matrix liquid crystal display.
In a further scheme, the central processing module comprises a microprocessor, a reset circuit and a clock circuit, and the microprocessor, the reset circuit and the clock circuit form a minimum system of the single chip microcomputer.
In a further scheme, the communication module comprises an RS232/RS485 serial communication module or an ethernet communication module, and the central processing module communicates with the power master station through the RS232/RS485 serial communication module or the ethernet communication module.
Therefore, the direct current analog quantity measuring device adopts the high-resolution direct current analog quantity sampling unit to carry out signal acquisition and AD conversion, and uses the 32-bit ARM microprocessor to calculate data, so that the high-precision and wide-range measuring function of the direct current analog quantity can be realized; meanwhile, the accuracy and stability of sampling precision are ensured by the design of the anti-interference circuit, the competitiveness of products can be improved, and the anti-interference circuit has market popularization advantages.
Furthermore, the application of the high-resolution isolated ADE7913 chip can realize that the sampling precision error of the direct-current voltage is less than or equal to +/-0.2 percent.
Furthermore, the voltage sampling range of the direct current analog quantity sampling circuit is 0V-240 VDC.
Furthermore, the zero drift processing is carried out by a software algorithm, and the read direct current sampling zero drift value is processed and memorized by the device only during the first power-on initialization. Of course, the utility model only processes the read direct current sampling zero drift value during the first power-on initialization and stores the value to Flash, and then correspondingly processes the zero drift value during the point-by-point sampling calculation.
Furthermore, the anti-surge interference and anti-electrical fast transient pulse group interference capability of the circuit meets the requirement of level 4.
Furthermore, the circuit design meets the withstand voltage level of 2KV, and is electrically isolated from other circuits.
Drawings
Fig. 1 is a schematic diagram of an embodiment of a dc analog sampling circuit according to the present invention.
Fig. 2 is a schematic circuit diagram of a central processing module in an embodiment of a dc analog sampling circuit according to the present invention.
Fig. 3 is a schematic circuit diagram of a dc analog sampling unit in an embodiment of a dc analog sampling circuit according to the present invention.
Fig. 4 is a schematic circuit diagram of a power supply unit in an embodiment of a dc analog sampling circuit according to the present invention.
Fig. 5 is a schematic circuit diagram of a display module in an embodiment of a dc analog sampling circuit according to the present invention.
Fig. 6 is a schematic circuit diagram of an RS232/RS485 serial communication module in an embodiment of the dc analog sampling circuit of the present invention.
Fig. 7 is a schematic circuit diagram of an ethernet communication module in an embodiment of the dc analog sampling circuit of the present invention.
The utility model is further explained with reference to the drawings and the embodiments.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the utility model without any inventive step, are within the scope of protection of the utility model.
Referring to fig. 1, the dc analog sampling circuit 100 of the present invention includes a dc analog sampling unit 10, a main control unit 20 and a power supply unit 30, where the power supply unit 30 outputs electric energy for the dc analog sampling unit 10 and the main control unit 20, respectively, to provide reliable working voltage for the whole system, the dc analog sampling unit 10 and the main control unit 20 perform information interaction through an SPI bus, and the dc analog sampling unit 10 is configured to collect a dc analog signal and output a corresponding digital signal to the main control unit 20.
In this embodiment, the dc analog sampling unit 10 includes an analog signal source 11, an analog-to-digital conversion module 12, and a working power supply for providing power, an input of the analog signal source 11 receives a dc analog signal, an output of the analog signal source 11 inputs a pseudo differential signal to the analog-to-digital conversion module 12, and an output of the analog-to-digital conversion module 12 inputs a corresponding digital signal to the main control unit 20.
In this embodiment, the main control unit 20 includes a central processing module 21, a display module 22 and a communication module 23, and the main control unit 20 transmits the dc voltage sampling value to the power master station through the communication module 23 and performs real-time display through the display module 22.
The analog-to-digital conversion module 12 includes an AD conversion chip U2, the analog signal source 11 inputs pseudo differential signals to ports V1P and V2P of the AD conversion chip U2, generates digital signals proportional to the levels of the input pseudo differential signals through the AD conversion chip U2, and transmits the digital signals to the main control unit 20 through the SPI bus. Specifically, the dc analog sampling unit 10 inputs the pseudo-differential signal voltage to the channels V1P and V2P of the AD conversion chip ADE7913 through the analog signal source 11, generates a 24-bit data word proportional to the input signal level through the internal processing of the AD conversion chip U2, and then transmits the digital signal to the microprocessor of the main control unit 20 through the SPI bus for the next calculation.
As shown in fig. 2, the central processing module 21 includes a microprocessor U3A, a reset circuit, and a clock circuit, and the microprocessor U3A, the reset circuit, and the clock circuit constitute a minimum system of a single chip microcomputer. Specifically, the microprocessor U3A adopts a 32-bit ARM microprocessor U3ASTM32F103ZET6 to perform data calculation and processing on the signal output by the dc analog sampling unit 10; calculating a real-time voltage value and displaying the real-time voltage value through a Hua-far liquid crystal HYG 16016020G; meanwhile, the central processing module 21 and the communication module 23 transmit data in real time, and the dc voltage sampling value is transmitted to the power master station 1 through a serial port (IEC101, modbus protocol) or an ethernet (IEC104 protocol) of the communication module 23; the function that the terminal can collect and send direct current is achieved overall.
Further, the CPU of the present embodiment selects a 32-bit ARM microprocessor U3ASTM32F103ZET6 with high integration and no bus-out chip to perform data calculation and processing on the signal output by the dc analog sampling unit 10; circuits such as peripheral clock/reset of the STM32F103ZET6 chip are simple to build, the IO port is flexible to control, and the use is very convenient; meanwhile, an external FLASH-64M storage chip AT45DB642D is configured in the system, 1024 historical events can be circularly recorded in real time, the loss is avoided when power is down, and the action records in the running process of the terminal can be retrieved conveniently.
Therefore, the direct current analog quantity sampling unit 10 of the utility model utilizes an ADE7913 chip with 24-bit sampling resolution to match with a peripheral circuit, and the microprocessor U3A selects a 32-bit ARM microprocessor to realize a direct current analog quantity sampling circuit with the direct current voltage sampling precision error less than or equal to +/-0.2%, the sampling wide range of 0V-240 VDC and the electromagnetic compatibility interference resistance capability of 4 levels.
As shown in fig. 3, the analog signal source 11 is composed of two loops of dc measurement channels, and each loop of dc measurement channel includes 1 voltage dependent resistor, 4 voltage dividing resistors, 1 sampling resistor, and 4 high-speed diodes. For example, one of the loop direct current measurement channels includes a voltage dependent resistor RT23, a voltage division resistor RL1, RL3, RL5, RL7, a sampling resistor R2, high-speed diodes D1, D2, D5, and D6. It can be seen that each loop of the dc measurement channel of this embodiment is a differential mode clamping device with 1 varistor 14D 471K; the 4 packaging pieces are 1206 voltage dividing resistors with the resistance value of 15K and the precision of +/-1%; 1 sampling resistor with the encapsulation of 0805, the resistance value of 120R and the precision of +/-1 percent; and 4 high-speed diodes 1N4148 and the input overvoltage protection and anti-interference circuit. The analog signal source 11 mainly generates and inputs pseudo differential signal voltages to the channels V1P, V2P of the AD conversion chip ADE 7913.
The analog-to-digital conversion module 12 of the present embodiment is formed by building a peripheral circuit by an AD conversion chip U2ADE 7913. The channels V1P, V2P of the chip detect the pseudo-differential signal voltage, are processed by the integrated circuits within the chip and generate 24-bit data words proportional to the input signal level, and then transmit the digital signals over the SPI bus to the microprocessor U3A of the master control unit 20 for further calculations.
The working power supply comprises an isolation power supply circuit and a linear voltage stabilizing circuit, the isolation power supply circuit is connected to a power supply and outputs a 5V power supply signal to the linear voltage stabilizing circuit through a filter capacitor, and the linear voltage stabilizing circuit outputs a 3.3V power supply signal to an AD conversion chip U2. Therefore, the working power supply of the embodiment is a +5V power supply obtained by building a filter capacitor by the Jinsheng yang isolation module B0505LS-1WR 3; and then a filter circuit is built by using the linear voltage stabilizer SPX1117M3-3.3 to finally obtain stable +3.3V, which is required by the work of an AD conversion chip U2. The design of the isolation power supply circuit is a measure for improving the capability of resisting EMC interference such as electrical fast transient pulse group interference, surge interference and the like, ensuring the accuracy of DC voltage sampling and simultaneously preventing a DC voltage loop from generating interference on other loops.
It should be noted that the power input is 220V or 48V/24V, which depends on the model of the power voltage reduction module (P1), and is produced and shipped according to the user's requirement (48V/24V is common when designing the circuit, and the reliable working range of the power input is DC19.2V-DC57.6V).
In this embodiment, referring to fig. 4, the power supply unit 30 includes an input port anti-interference module, a power supply voltage reduction module and a linear regulator U1, the input port anti-interference module is connected to the power supply voltage reduction module, the power supply voltage reduction module is connected to the linear regulator U1, and the input port anti-interference module is further connected to a positive and negative terminal input protection module.
The input port anti-interference module comprises a differential mode piezoresistor RT3, a common mode piezoresistor RT1, RT2, a six-hole magnetic bead inductor FB1, FB2, a common mode inductor LL1, a safety capacitor CL1 and Y capacitors CY1-CY 7. It can be seen that the input port anti-interference module of the embodiment is a functional circuit with surge voltage clamping and high-frequency group pulse signal processing, which is composed of 1 differential mode varistor RT3, 2 common mode varistors RT1/RT2, 2 differential mode six-hole magnetic beads FB1/2, 1 22mH common mode inductor LL1, 1 safety capacitor CL1 of 275VAC/0.1uF, and 2Y capacitors CY1/CY2-102/3KV, and ensures the stability and reliability of power input.
The positive and negative port input protection module comprises a diode V1, the negative electrode of a diode V1 is connected with one end of a six-hole magnetic bead inductor FB1, and the positive electrode of a diode V1 is connected with the power input end and one end of a differential mode voltage dependent resistor RT 3. Therefore, the input protection module of the positive and negative electrode ports in the embodiment is composed of 1 diode 1N4007-V1, and the power supply circuit can have an anti-reverse connection protection function. When the input positive and negative polarities are connected reversely, the device protection does not operate; when the positive and negative polarities are recovered to normal, the device can operate reliably.
The power supply voltage reduction module comprises an AC-DC power supply module or a DC-DC power supply module, such as P1, 24V power supply signals and 5V power supply signals are output by the AC-DC power supply module or the DC-DC power supply module, and the 5V power supply signals are converted into 3.3V power supply signals by the linear voltage stabilizer to be output. It can be seen that the power voltage reduction module of the embodiment reduces the voltage of +24VDC and +5VDC output by the P1 jingshang power module LHE10-20D0524(AC-DC mode) or the URB2405YMD-20WR3(DC-DC mode); the +5VDC power supply is reused to build a filter circuit by a U1 linear voltage stabilizer SPX1117M3-3.3 to obtain a stable +3.3V power supply. The +5VDC power and the +3.3V power are provided for the main control unit 20 to work normally.
In the present embodiment, as shown in fig. 5, the display module 22 is provided with a dot matrix type liquid crystal display JP1 and 10 patch tact switches connected thereto. Therefore, the man-machine interaction interface of the embodiment is configured with the Huayuan liquid crystal HYG16016020G multi-dot matrix liquid crystal display screen and 10 patch tact switches. The liquid crystal display screen is used for displaying real-time measured values DC1 and DC2 of the two paths of direct current voltages, and the display precision is kept at three decimal places; and other protection function technical parameters of the intelligent terminal, action historical events, system time and other menus. The 10 patch tact switches are used for page turning browsing of menus, setting of protection function fixed values, calibrating of analog quantity sampling channel coefficients, setting of system time and other related technical parameters.
In this embodiment, as shown in fig. 6 and 7, the communication module 23 includes an RS232/RS485 serial communication module 23 or an ethernet communication module 23, and the central processing module 21 communicates with the power master station 1 through the RS232/RS485 serial communication module 23 or the ethernet communication module 23. Therefore, the communication module 23 of the embodiment is 2-path multiplexing (jumper cap conversion) RS232/RS485 serial port communication formed by respectively building peripheral circuits through a chip SP3232EEN-L and a chip SP485 EEN-L; and an Ethernet communication module 23 composed of a chip CH9121 and a peripheral circuit. The central processing module 21 and the communication module 23 perform real-time data transmission, and the dc voltage sampling value is transmitted to the power master station 1 through an RS232/RS485 serial port (IEC101 protocol, modbus protocol) or an ethernet interface (IEC104 protocol) of the communication module 23.
Therefore, the direct current analog quantity measuring device can realize the high-precision and wide-range measuring function of the direct current analog quantity by adopting the high-resolution direct current analog quantity sampling unit 10 to carry out signal acquisition and AD conversion and using the 32-bit ARM microprocessor U3A to calculate data; meanwhile, the design of the anti-interference circuit ensures the accuracy and stability of sampling precision, improves the competitiveness of products and has market popularization advantage.
Furthermore, the application of the high-resolution isolated ADE7913 chip can realize that the sampling precision error of the direct-current voltage is less than or equal to +/-0.2 percent.
Furthermore, the voltage sampling range of the direct current analog quantity sampling circuit is 0V-240 VDC.
Furthermore, the zero drift processing is carried out by a software algorithm, and the read direct current sampling zero drift value is processed and memorized by the device only during the first power-on initialization.
Furthermore, the anti-surge interference and anti-electrical fast transient pulse group interference capability of the circuit meets the requirement of level 4.
Furthermore, the circuit design meets the withstand voltage level of 2KV, and is electrically isolated from other circuits.
It should be noted that the above is only a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modifications made to the present invention by using the design concept also fall within the protection scope of the present invention.
Claims (10)
1. A DC analog sampling circuit, comprising:
the direct current analog quantity sampling unit is used for acquiring a direct current analog quantity signal and outputting a corresponding digital signal to the main control unit;
the direct current analog quantity sampling unit comprises an analog quantity signal source, an analog-to-digital conversion module and a working power supply for providing power supply, wherein the input of the analog quantity signal source receives a direct current analog quantity signal, the output of the analog quantity signal source inputs a pseudo differential signal to the analog-to-digital conversion module, and the output of the analog-to-digital conversion module inputs a corresponding digital signal to the main control unit;
the main control unit comprises a central processing module, a display module and a communication module, and transmits a direct-current voltage sampling value to the power master station through the communication module and displays the direct-current voltage sampling value in real time through the display module.
2. The direct current analog quantity sampling circuit according to claim 1, characterized in that:
the analog-to-digital conversion module comprises an AD conversion chip, wherein a pseudo-differential signal is input to ports V1P and V2P of the AD conversion chip by an analog signal source, a digital signal proportional to the level of the input pseudo-differential signal is generated by the AD conversion chip, and the digital signal is transmitted to the main control unit through an SPI bus.
3. The dc analog sampling circuit of claim 2, wherein:
the analog quantity signal source is composed of at least two loop direct current measuring channels, and each loop direct current measuring channel comprises 1 piezoresistor, 4 divider resistors, 1 sampling resistor and 4 high-speed diodes.
4. The direct current analog quantity sampling circuit according to claim 3, characterized in that:
the working power supply comprises an isolation power supply circuit and a linear voltage stabilizing circuit, the isolation power supply circuit is connected to a power supply and outputs a 5V power supply signal to the linear voltage stabilizing circuit through a filter capacitor, and the linear voltage stabilizing circuit outputs a 3.3V power supply signal to the AD conversion chip.
5. The direct current analog quantity sampling circuit according to claim 1, characterized in that:
the power supply unit comprises an input port anti-interference module, a power voltage reduction module and a linear voltage stabilizer, wherein the input port anti-interference module is connected with the power voltage reduction module, the power voltage reduction module is connected with the linear voltage stabilizer, and a positive electrode port and a negative electrode port input protection module are further connected to the input port anti-interference module.
6. The direct current analog quantity sampling circuit according to claim 5, characterized in that:
the input port anti-interference module comprises a differential mode piezoresistor RT3, a common mode piezoresistor RT1, RT2, a six-hole magnetic bead inductor FB1, FB2, a common mode inductor LL1, a safety regulation capacitor CL1 and Y capacitors CY1-CY 7;
the positive and negative electrode port input protection module comprises a diode V1, the negative electrode of the diode V1 is connected with one end of the six-hole magnetic bead inductor FB1, and the positive electrode of the diode V1 is connected with the power input end and one end of the differential mode piezoresistor RT 3.
7. The direct current analog quantity sampling circuit according to claim 5, characterized in that:
the power supply voltage reduction module comprises an AC-DC power supply module or a DC-DC power supply module, 24V power supply signals and 5V power supply signals are output by the AC-DC power supply module or the DC-DC power supply module, and the 5V power supply signals are converted into 3.3V power supply signals through the linear voltage stabilizer to be output.
8. The direct-current analog quantity sampling circuit according to any one of claims 1 to 7, characterized in that:
the display module is provided with a dot-matrix liquid crystal display screen and 10 patch tact switches connected with the dot-matrix liquid crystal display screen.
9. The direct-current analog quantity sampling circuit according to any one of claims 1 to 7, characterized in that:
the central processing module comprises a microprocessor, a reset circuit and a clock circuit, and the microprocessor, the reset circuit and the clock circuit form a minimum system of the single chip microcomputer.
10. The direct-current analog quantity sampling circuit according to any one of claims 1 to 7, characterized in that:
the communication module comprises an RS232/RS485 serial communication module or an Ethernet communication module, and the central processing module is communicated with the power master station through the RS232/RS485 serial communication module or the Ethernet communication module.
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| CN202120829119.5U CN215340044U (en) | 2021-04-21 | 2021-04-21 | Direct current analog quantity sampling circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120829119.5U CN215340044U (en) | 2021-04-21 | 2021-04-21 | Direct current analog quantity sampling circuit |
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| CN215340044U true CN215340044U (en) | 2021-12-28 |
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