Portable field calibration device for digital unit of electronic mutual inductor
By using DC power supply and a dedicated DAC power supply module, the problems of high cost, large size, and temperature rise affecting accuracy caused by AC power supply in the existing technology are solved, and the high accuracy and stability of the portable electronic current transformer digital unit verification device are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2026-03-27
AI Technical Summary
Existing electronic instrument transformer calibration devices use an AC power supply scheme, which results in high cost, large size, and temperature rise affecting accuracy.
A DC power supply scheme is adopted, which converts the input DC power into different voltages through the power management module to power various components. A dedicated power supply module is designed for the DAC chip, including boost, voltage regulation and voltage reference devices to reduce voltage noise and temperature drift.
It reduces cost and size, minimizes temperature rise, improves measurement accuracy and stability, and ensures the stability of the analog signal output from the signal source module.
Smart Images
Figure CN224052400U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a kind of for verifying electronic mutual inductor digitization unit's verification device. BACKGROUND
[0002] Electronic mutual inductor as the key measuring equipment in power system, its precision directly influences the reliability of electric energy metering, relay protection etc. core function. In order to calibrate electronic mutual inductor digitization unit (ADMU) on site, it needs to use the calibration equipment with analog small signal output ability and digital quantity back sampling function to verify. Such verification device usually includes control and operation module, signal source module, signal conditioning module and data acquisition and processing module. As shown in Figure 1 CPU and FPGA two parts are usually included in control and operation module, responsible for and external man-machine interactive module communication connection. When working, CPU generates corresponding normalized waveform transmission to FPGA according to the set parameter, and FPGA stores waveform in RAM and passes to signal source module to generate periodic waveform data. Signal conditioning module is amplified according to periodic waveform data, generates output analog signal and outputs to the equipment to be verified, and the FT3 signal output by the equipment to be verified is collected by data acquisition and processing module, and after conversion, it is transmitted to FPGA for decoding processing, and finally CPU compares the decoding result with CPU output signal, and obtains verification result.
[0003] However, existing verification device generally uses power frequency power supply scheme, and although this architecture can meet basic verification demand, there are the following problems in actual application: AC220V to direct current conversion needs to be completed in the device, not only high cost, but also equipment bulky, inconvenient for on-site inspection use and mobile. At the same time, temperature drift, device aging and other problems caused by temperature rise of ac-dc device long time operation affect verification accuracy. UTILITY MODEL CONTENT
[0004] The utility model proposes a kind of portable electronic mutual inductor digitization unit on-site verification device, its purpose is: solve the problem of high cost, bulky, temperature rise affects accuracy caused by existing ac power supply scheme.
[0005] The utility model technical scheme is as follows:
[0006] The portable electronic mutual inductor digitizing unit field calibration device comprises a control and operation module, a signal source module, a signal conditioning module and a data acquisition and processing module, the signal output end of the control and operation module is connected with the signal input end of the signal source module, the signal output end of the signal source module is connected with the signal input end of the signal conditioning module, the signal output end of the signal conditioning module is connected with the signal input end of the calibrated device, and the signal output end of the calibrated device is connected with the signal acquisition input end of the control and operation module through the data acquisition and processing module; the portable electronic mutual inductor digitizing unit field calibration device further comprises a power management module, which is used for converting the input DC voltage connected with the calibration device into different DC voltages to supply power for the control and operation module, the signal source module, the signal conditioning module, the data acquisition and processing module and the calibrated device.
[0007] The power management module comprises a DAC special power supply module used for supplying power for the DAC chip in the signal source module; the DAC special power supply module comprises a booster D1, a second linear voltage stabilizer D2 and a voltage reference device D3; the booster D1 raises the DC voltage connected with the calibration device to a first voltage, the second linear voltage stabilizer D2 is used for stabilizing the first voltage to a second voltage, and the voltage reference device D3 is used for reducing the second voltage to a reference voltage VREF required by the DAC chip.
[0008] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the Vin pin of the booster D1 is connected with the power supply access end of the calibration device, the power supply access end is further connected to the SW pin of the booster D1 through the electric reactance L1, the SW pin of the booster D1 is connected with the anode of the diode V1, and the cathode of the diode V1 is used for outputting the first voltage; the cathode of the diode V1 is further connected to the ground through the resistors R1 and R2 connected in series, the connecting point between the resistors R1 and R2 is connected with the FB pin of the booster D1, and the GND pin of the booster D1 is grounded.
[0009] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the power supply access end and the ground end are connected with the capacitor C1.
[0010] The cathode of the diode V1 and the ground end are further connected with the capacitors C2, C3 and C4 in parallel.
[0011] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the Vin pin of the second linear voltage stabilizer D2 is used for inputting the first voltage, the GND pin is grounded, and the voltage output end is used for outputting the second voltage.
[0012] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, a capacitor C5 and a capacitor C6 are connected in parallel between the voltage output end and the ground end of the second linear voltage stabilizer D2.
[0013] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the voltage output end of the second linear voltage stabilizer D2 is connected to the voltage input end VIN of the voltage reference device D3 through a low-pass filter circuit.
[0014] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the low-pass filter circuit includes a resistor R3 and a capacitor C7.
[0015] The voltage output end of the second linear voltage stabilizer D2 is connected to the ground end through a resistor R3 and a capacitor C7 connected in series, and the connection point between the resistor R3 and the capacitor C7 is connected to the voltage input end VIN of the voltage reference device D3; the voltage output end VOUT of the voltage reference device D3 is used to output a reference voltage VREF, and the GND pin is grounded.
[0016] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, a capacitor C8 is connected in parallel across the capacitor C7.
[0017] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the calibration device is connected to 5V DC through a power supply interface or a battery, the first voltage is 12V, and the second voltage is 10V.
[0018] As a further improvement of the portable electronic mutual inductor digitizing unit field calibration device, the power management module further includes a voltage converter, a first linear voltage stabilizer, a module power supply, a third linear voltage stabilizer, a fourth linear voltage stabilizer, and a fifth linear voltage stabilizer.
[0019] The voltage converter is used to convert the input 5V voltage to -12V, and the first linear voltage stabilizer is used to convert the -12V voltage to -10V; the second voltage 10V and the -10V voltage output by the first linear voltage stabilizer are used to supply power to the signal conditioning module.
[0020] The module power supply is used to convert the input 5V voltage to 24V to supply power to the device being calibrated.
[0021] The third linear voltage stabilizer is used for converting the accessed 5V voltage into 3.3V, the fourth linear voltage stabilizer is used for converting the 3.3V voltage into 1.2V, and the fifth linear voltage stabilizer is used for converting the 3.3V voltage into 2.5V; the 3.3V is used for supplying power for a CPU in the signal source module, and the 3.3V, 1.2V and 2.5V are used for jointly supplying power for an FPGA in the signal source module; the 5V voltage and the 3.3V voltage are also used for supplying power for a data acquisition and processing module.
[0022] Compared with the prior art, the utility model has following positive effects:
[0023] 1. The utility model adopts direct current power supply scheme, converts input direct current into different voltages through power management module, and supplies power for each component. Compared with traditional alternating current power supply scheme, this design saves high-power components, reduces cost, greatly reduces volume and weight (can be reduced to below 1kg), and simultaneously, the whole machine power consumption is reduced (less than 5W), effectively solves the temperature rise problem of traditional equipment caused by long time work, avoids calibration error caused by temperature drift and component aging, and thus improves measurement precision and stability.
[0024] 2. The utility model separately designs DAC special power supply module for the DAC chip, the module first boosts input 5V voltage to 12V, reduces voltage noise, then reduces voltage to 10V to further reduce voltage noise to dozens of uV level, and finally further reduces voltage to the reference voltage VREF required by the DAC chip through voltage reference device, at this time, voltage noise is reduced to several uV level, and temperature coefficient is not more than 3ppm / ℃, and the stability of the analog signal output by the signal source module is ensured. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 It is the working principle diagram of the electronic mutual inductor digital unit field calibration device;
[0026] Figure 2 It is the architecture diagram of the power management module in the utility model;
[0027] Figure 3 It is the circuit diagram of the DAC special power supply module in the power management module. DETAILED DESCRIPTION
[0028] The technical scheme of the utility model will be described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments.
[0029] As Figure 1The portable electronic mutual inductor digital unit on-site calibration device comprises a control and operation module, a signal source module, a signal conditioning module and a data acquisition and processing module. The signal output end of the control and operation module is connected with the signal input end of the signal source module, the signal output end of the signal source module is connected with the signal input end of the signal conditioning module, the signal output end of the signal conditioning module is connected with the signal input end of the device to be calibrated, and the signal output end of the device to be calibrated is connected with the signal acquisition input end of the control and operation module through the data acquisition and processing module.
[0030] The portable electronic mutual inductor digital unit on-site calibration device further comprises a power management module, which is used for converting the input DC voltage connected with the calibration device into different DC voltages to supply power to the control and operation module, the signal source module, the signal conditioning module, the data acquisition and processing module and the device to be calibrated.
[0031] The calibration device is connected with 5V DC through a power supply interface (preferably a Type-C interface) or a battery.
[0032] Specifically, as Figure 2 and 3 , the power management module comprises a DAC special power supply module used for supplying power to the DAC chip in the signal source module.
[0033] The DAC special power supply module comprises a booster D1 (LV28 series chip), a second linear voltage stabilizer D2 (78L series chip, and a specific model is 78L10) and a voltage reference device D3 (model ADR435B). The booster D1 raises the DC voltage connected with the calibration device to a first voltage 12V, the second linear voltage stabilizer D2 is used for stabilizing the first voltage to a second voltage 10V, and the voltage reference device D3 is used for reducing the second voltage to the reference voltage VREF required by the DAC chip.
[0034] Specifically, as Figure 3 , a capacitor C1 is connected between the power supply access end 5V and the ground end for filtering. The Vin pin of the booster D1 is connected with the power supply access end of the calibration device, the power supply access end is further connected to the SW pin of the booster D1 through the reactance L1, the SW pin of the booster D1 is connected with the anode of the diode V1, and the cathode of the diode V1 is used for outputting the first voltage 12V. The cathode of the diode V1 is further connected to the ground through the resistors R1 and R2 connected in series, and the connection point between the resistors R1 and R2 is connected with the FB pin of the booster D1; the GND pin of the booster D1 is grounded.
[0035] Further, the capacitor C2, the capacitor C3 and the capacitor C4 are connected in parallel between the cathode of the diode V1 and the ground end for filtering.
[0036] The Vin pin of the second linear voltage stabilizer D2 is used to input the first voltage 12V, the GND pin is grounded, and the voltage output end is used to output the second voltage 10V.
[0037] The voltage output end of the second linear voltage stabilizer D2 is connected with the ground end through the parallel connection of the capacitor C5 and the capacitor C6, which are used to filter and store current for the signal conditioning module.
[0038] The voltage output end of the second linear voltage stabilizer D2 is connected with the voltage input end VIN of the voltage reference device D3 through a low-pass filter circuit. Specifically, the low-pass filter circuit includes the resistor R3 and the capacitor C7. The voltage output end of the second linear voltage stabilizer D2 is connected with the ground end through the resistor R3 and the capacitor C7 connected in series. The connection point between the resistor R3 and the capacitor C7 is connected with the voltage input end VIN of the voltage reference device D3. The voltage output end VOUT of the voltage reference device D3 is used to output the reference voltage VREF, and the GND pin is grounded. The capacitor C7 is also connected with the capacitor C8 in parallel.
[0039] The DAC chip has high requirements for the quality of the supply voltage, and therefore a dedicated DAC reference voltage source needs to be used for power supply. When the DAC dedicated power supply module is working, the input 5V voltage is boosted to 12V through the booster D1. At this time, the voltage noise is large, reaching the mV level. C1 is a filter capacitor, R1 and R2 are feedback resistors, and different output voltages are obtained by setting the resistance values of R1 and R2. The output 12V is stepped down to 10V through the second linear voltage stabilizer D2. At this time, the voltage noise is further reduced to the level of dozens of uV, but the temperature drift is large. The output 10V is stepped down to VREF through the voltage reference device D3, so as to match the power supply requirements of the DAC chip. At this time, the voltage noise of VREF is at the level of several uV, and the maximum temperature coefficient is 3ppm / ℃, which can ensure the stability of the analog signal output by the signal source module.
[0040] As shown in FIG. 1, Figure 2 The power management module further includes a voltage converter (LV28 series chip), a first linear voltage stabilizer (79L series chip), a module power supply (Jinshengyang F05), a third linear voltage stabilizer (TVL117 chip), a fourth linear voltage stabilizer (TLV700 series chip), and a fifth linear voltage stabilizer (TLV700 series chip).
[0041] The voltage converter is used to convert the input 5V voltage to -12V, and the first linear voltage stabilizer is used to convert the -12V voltage to -10V. The second voltage 10V and the -10V voltage output by the first linear voltage stabilizer are used to supply power to the signal conditioning module. The linear voltage stabilizer can provide low-noise ±10V, ensuring signal quality.
[0042] The module power supply is used to convert the accessed 5V voltage into 24V to power the device under test.
[0043] The third linear voltage stabilizer is used to convert the accessed 5V voltage into 3.3V, the fourth linear voltage stabilizer is used to convert the 3.3V voltage into 1.2V, and the fifth linear voltage stabilizer is used to convert the 3.3V voltage into 2.5V. The 3.3V is used to power the CPU in the signal source module, and the 3.3V, 1.2V and 2.5V are used to power the FPGA in the signal source module. The 5V voltage and the 3.3V voltage are also used to power the data acquisition and processing module.
[0044] It should be noted that the skilled in the art can implement the related voltage conversion circuit according to the above chip specification.
[0045] The man-machine interaction module is connected to the present calibration device. The man-machine interaction module has a touchable serial screen. The serial screen is fast, low in price, easy to operate, and can display relevant data such as relative error and version information of the device under test, and can monitor the accuracy of data transmission of the device under calibration, such as whether there are error codes and error check bits. Before shipment, the calibration device can be calibrated by using the software compensation method based on the man-machine interaction module: the effective value of the analog signal actually output by the present calibration device is measured by using a six-bit half digital multimeter, the measured value is written on the calibration interface of the serial screen and fed back to the single-chip microcomputer for software compensation, and the single-chip microcomputer transmits the compensated value to the FPGA, and then controls the DAC chip in the signal source module to output an analog small signal, and then obtains the calibrated analog signal after subsequent operation and processing. The specific compensation algorithm is a conventional technical means in the art, which will not be described here.
[0046] As Figure 1, when working, the serial screen of the man-machine interaction module sets parameters, for example: the measured voltage effective value is 1.876V, the measured current effective value is 1V, etc. The serial screen of the man-machine interaction module transmits the set parameters to the STM32 series single-chip microcomputer (CPU) through serial communication. The CPU generates corresponding normalized waveforms according to the set parameters and transmits the normalized waveforms to the FPGA, the FPGA stores the waveforms in the RAM and transmits the waveforms to the signal source module, and the signal source module generates periodic waveform data (analog signal) through the I / O port control DAC chip. Preferably, the signal source module adopts a double-DAC scheme, which is responsible for generating normalized waveforms and amplitude control waveforms respectively. The signal conditioning module is used for filtering and amplifying, and it obtains the voltage signal Uo based on the normalized waveforms and the amplitude control waveforms through operation. Among them, the operational amplifier adopts a chip with low input bias current (nA level) and low voltage noise density (nV level), and the digital-to-analog conversion chip adopts 16 bits, which ensures the resolution and accuracy of the output analog signal. The operational amplifier cooperates with 10KΩ and 20KΩ high-precision metal foil resistors with a precision of 0.01%, so that the maximum error of the reverse amplification multiple of the operational amplifier is about 0.02%; the temperature drift of the metal foil resistor is 5ppm / ℃, the resistance change of the 10KΩ resistor is 0.05Ω per degree Celsius, and the resistance change of the 20KΩ resistor is 0.1Ω per degree Celsius, which is less than the precision change amount, so the long-term running error change of the analog signal is less than 0.02%, and therefore the calibration device can maintain a long-term high-precision and high-stability working state. The analog signal output by the signal conditioning module is output to the device to be calibrated. After receiving the analog signal, the device to be calibrated converts it into a digital signal and performs Manchester coding according to the coding standard of 61850, and then transmits it to the calibration device through the FT3 channel. The output FT3 signal is collected and received by the data acquisition and processing module, and then the 5V signal is converted into a 3.3V signal through a level conversion circuit and transmitted to the FPGA for decoding processing. The decoded data is transmitted to the CPU through the SPI (using the DMA mode) of the FPGA, the CPU calculates the relative error of the decoded digital unit data and the original output analog signal of the CPU (high-precision back sampling signal can also be used), and then displays the calculated error and the related information of the measured device through the serial screen.
[0047] It should be noted that, for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. The scope of the present application is defined by the claims rather than the above description.
Claims
1. A portable electronic mutual inductor digital unit field calibration device, comprising a control and operation module, a signal source module, a signal conditioning module, and a data acquisition and processing module, the signal output end of the control and operation module is connected with the signal input end of the signal source module, the signal output end of the signal source module is connected with the signal input end of the signal conditioning module, the signal output end of the signal conditioning module is connected with the signal input end of the device to be calibrated, and the signal output end of the device to be calibrated is connected with the signal acquisition input end of the control and operation module through the data acquisition and processing module; characterized in that: The power management module is used for converting the input direct current voltage of the access checking device into different direct current voltages to supply power for the control and operation module, the signal source module, the signal conditioning module, the data acquisition and processing module and the checked equipment. The power management module comprises a DAC dedicated power supply module for supplying power for the DAC chip in the signal source module; the DAC dedicated power supply module comprises a voltage booster D1, a second linear voltage stabilizer D2 and a voltage reference device D3; the voltage booster D1 raises the direct current voltage accessed by the checking device to a first voltage, the second linear voltage stabilizer D2 is used for stabilizing the first voltage to a second voltage, and the voltage reference device D3 is used for lowering the second voltage to a reference voltage VREF required by the DAC chip.
2. The portable electronic transformer digitalizing unit field proof device of claim 1, wherein: The Vin pin of the voltage booster D1 is connected with a power supply access end of the checking device, the power supply access end is further connected with the SW pin of the voltage booster D1 through an electric reactance L1, the SW pin of the voltage booster D1 is connected with the positive pole of a diode V1, and the negative pole of the diode V1 is used for outputting the first voltage; the negative pole of the diode V1 is further connected with the ground through a resistor R1 and a resistor R2 connected in series, the connecting point between the resistor R1 and the resistor R2 is connected with the FB pin of the voltage booster D1, and the GND pin of the voltage booster D1 is grounded.
3. The portable electronic transformer digitalizing unit field proof device of claim 2, wherein: The power supply access end and the ground end are connected with a capacitor C1. The negative pole of the diode V1 and the ground end are further connected with a capacitor C2, a capacitor C3 and a capacitor C4 in parallel.
4. The portable electronic transformer digitalizing unit field proof device of claim 1, wherein: The Vin pin of the second linear voltage stabilizer D2 is used for inputting the first voltage, the GND pin is grounded, and the voltage output end is used for outputting the second voltage.
5. The portable electronic transformer digitalizing unit field proof device of claim 4, wherein: The voltage output end of the second linear voltage stabilizer D2 and the ground end are connected with a capacitor C5 and a capacitor C6 in parallel.
6. The portable electronic transformer digitalizing unit field proof device of claim 1, wherein: The voltage output end of the second linear voltage stabilizer D2 is connected with the voltage input end VIN of the voltage reference device D3 through a low-pass filter circuit.
7. The portable electronic transformer digitalizing unit field proof device of claim 6, wherein: The low-pass filter circuit comprises a resistor R3 and a capacitor C7. The voltage output end of the second linear voltage stabilizer D2 is connected with the ground end through the resistor R3 and the capacitor C7 connected in series, the connecting point between the resistor R3 and the capacitor C7 is connected with the voltage input end VIN of the voltage reference device D3, the voltage output end VOUT of the voltage reference device D3 is used for outputting the reference voltage VREF, and the GND pin is grounded.
8. The portable electronic transformer digitalizing unit field proof device of claim 7, wherein: The capacitor C7 is connected with a capacitor C8 in parallel at both ends.
9. The portable electronic transformer digitalizing unit field proof device of claim 1, wherein: The checking device accesses 5V direct current through a power supply interface or a battery, the first voltage is 12V, and the second voltage is 10V.
10. The portable electronic transformer digitalizing unit field proof device of claim 9, wherein: The power management module further comprises a voltage converter, a first linear voltage stabilizer, a module power supply, a third linear voltage stabilizer, a fourth linear voltage stabilizer and a fifth linear voltage stabilizer. The voltage converter is used for converting the accessed 5V voltage into -12V, and the first linear voltage stabilizer is used for converting the -12V voltage into -10V; the second voltage 10V and the -10V voltage output by the first linear voltage stabilizer are used for supplying power for the signal conditioning module. The module power supply is used for converting the accessed 5V voltage into 24V to supply power for the checked equipment. The third linear voltage stabilizer is used for converting the accessed 5V voltage into 3.3V, the fourth linear voltage stabilizer is used for converting the 3.3V voltage into 1.2V, and the fifth linear voltage stabilizer is used for converting the 3.3V voltage into 2.5V; the 3.3V is used for supplying power for the CPU in the signal source module, and the 3.3V, 1.2V and 2.5V are used for supplying power for the FPGA in the signal source module; the 5V voltage and the 3.3V voltage are also used for supplying power for the data acquisition and processing module.