CN110456301A - Data Analysis Field Metering Device Calibrator - Google Patents

Abstract

The present invention discloses a calibrator for data analysis on-site metering devices, including a DC/DC isolated power supply and sequentially connected signal sampling modules, signal conditioning modules, A/D conversion modules, FPGA modules, DSP modules and ARM modules, and the signal conditioning modules include mutual Connected signal anti-aliasing filter and programmable gain amplifier, the signal sampling module includes a current gear switching circuit connected to the input end of the signal anti-aliasing filter, the current gear switching circuit is provided with at least 4 switching gears, DSP The module is also connected with the current gear switching circuit and the program-controlled gain amplifier respectively, and is used for controlling the current gear switching circuit to switch gears and controlling the program-controlled gain amplifier to amplify signals. The DSP module can automatically switch the current gear according to the size of the sampling current, and amplify the sampling current through a program-controlled gain amplifier, which can improve the measurement accuracy of the on-site calibrator; DC/DC isolated power supply is used to reduce the output ripple of the power supply , improve system stability.

Description

Data Analysis Field Metering Device Calibrator

technical field

The invention relates to the field of electric power metering equipment, in particular to a calibrator for a field metering device for data analysis.

Background technique

The electric energy meter calibrator is a test instrument integrating electric parameter measurement, electric energy meter calibration and wiring judgment. The most basic function of the electric energy meter on-site calibrator is the on-site calibration of the electric energy meter error. The error grades of the on-site calibrator are divided into 0.01, 0.02, 0.05, 0.1, 0.2 and 0.5. Smaller, the higher the accuracy requirement, the higher the performance requirement for the on-site calibrator.

At present, the on-site calibrator in the domestic market generally has an error level of 0.1 or 0.2. On the one hand, it is because the error level of 0.1 or 0.2 can meet the needs of most on-site calibration test sites. On the other hand, On the one hand, it is because the higher error level requires higher accuracy and stability of the on-site calibrator. The on-site calibration of the electric energy meter is to verify the installed electric energy meter under the common load state of the power grid. The detection current of the calibrator is often much smaller than the calibration current (range) of the electric energy meter, and the current calibration current of the on-site calibrator is only 1A and 5A two gears, the measurement accuracy is low, it is difficult to meet the requirements of higher error levels.

The higher the measurement accuracy of the on-site calibrator, the higher the requirement for the stability of the circuit system. The field calibrator on the market is generally powered by switching power supply, and the output of switching power supply has ripple, which is a phenomenon caused by the voltage fluctuation of switching power supply, because switching power supply is generally rectified and stabilized by AC power supply. It is formed by other links, which inevitably has some AC components in the DC stable value. This AC component superimposed on the DC stable value is called ripple, and the ripple will reduce the efficiency of the power supply and affect the power supply. The stability of the circuit system of the on-site calibrator.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a calibrator for data analysis on-site metering devices, which is used to solve the problem that the current on-site calibration accuracy level is not high.

Content of the present invention is as follows:

The calibrator of the data analysis site metering device includes a signal sampling module, a signal conditioning module, an A/D conversion module, an FPGA module, a DSP module and an ARM module connected in sequence, and also includes a signal sampling module and the signal conditioning module respectively module, the FPGA module, the DSP module and the DC/DC isolated power supply connected to the ARM module, the signal conditioning module includes an interconnected signal anti-aliasing filter and a programmable gain amplifier, and the signal sampling module includes A current gear switching circuit connected to the input end of the signal anti-aliasing filter, the current gear switching circuit is provided with at least 4 switching gears, and the DSP module is also connected with the current gear switching circuit and the programmable gain amplifier respectively connected, and used to control the current gear switching circuit for gear switching and control the program-controlled gain amplifier for signal amplification.

Preferably, the signal sampling module further includes a current mutual inductance sampling circuit and a clamp meter sampling circuit, and the current mutual inductance sampling circuit and the clamp meter sampling circuit are respectively connected to the current gear switching circuit through a switch circuit.

Preferably, the current gear switching circuit includes a sequentially connected microprocessor U31, a latch, and a switch unit, the microprocessor U31 is also connected to the DSP module, and the switch unit includes at least four channels of switch chips, the second A voltage divider circuit, the first operational amplifier U16 and the second operational amplifier U17, the noninverting input terminal of the second operational amplifier U17 is connected to the switch circuit, the inverting input terminal of the second operational amplifier U17 is grounded through the resistor R50, and the second operational amplifier U17 is grounded through the resistor R50. The output terminal of the second operational amplifier U17 is connected with the signal anti-aliasing filter, the first voltage divider circuit, the switch chip and the first operational amplifier U16 are connected in sequence to form the feedback loop of the second operational amplifier U17, and the control of the switch chip connected to the latch.

Preferably, the first voltage dividing circuit includes a resistor R109, a resistor R59, a resistor R60, a resistor R61 and a resistor R68 connected in sequence with an accuracy of 0.05%.

Preferably, the programmable gain amplifier has 4 built-in differential channels and is used to provide gains of 1 times, 4 times, 16 times and 64 times.

Preferably, the DC/DC isolated power supply includes a controllable switch unit, an isolated transformer unit and a voltage output unit connected in sequence, and the voltage output unit includes a step-down regulator unit for outputting the first voltage and a voltage regulator unit for outputting the second voltage. The voltage rectification and filtering unit, the isolation and transformation unit are connected to the control terminal of the controllable switch unit through the control logic unit.

Preferably, the control logic unit and the controllable switch unit are integrated in a DC/DC control chip U2, and the isolation and transformation unit adopts a high-frequency transformer T1 including two sets of secondary windings, and the high-frequency transformer T1 The first secondary winding is connected to the step-down voltage stabilizing unit, and the second secondary winding of the high frequency transformer T1 is connected to the voltage output unit.

Preferably, the step-down voltage stabilizing unit includes a voltage stabilizing chip U1, the input terminal of the voltage stabilizing chip U1 is connected with a first filter, the first filter includes tantalum capacitors E1 and C2 connected in parallel, and the voltage stabilizing chip U1 The output end is connected with a second filter, the second filter includes an LC filter circuit composed of an inductor L1, a tantalum capacitor E2 and a capacitor C3, and the rectification filter unit includes a rectifier bridge composed of diodes D5, D6, D7 and D8 and A third filter and a fourth filter connected to the rectifier bridge, the third filter includes a capacitor C5 and a tantalum capacitor E5 connected in parallel, and the fourth filter includes a tantalum capacitor E6 and a capacitor C8 connected in parallel.

The beneficial effects of the present invention are: compared with the existing two switching gears, the present invention uses at least four gears to further refine the measurement unit value of the current, which is beneficial to improve the accuracy of small signal measurement, and the DSP module can The size of the current automatically switches the current gear, and the sampling current is amplified by the program-controlled gain amplifier, which is conducive to improving the measurement accuracy of the on-site calibrator; the invention adopts a DC/DC isolated power supply to reduce the output ripple of the power supply and improve The stability of the circuit system.

Description of drawings

Fig. 1 shows the overall principle block diagram of the embodiment of the present invention;

Fig. 2 shows the microprocessor circuit of the current gear switching circuit of the embodiment of the present invention;

Fig. 3 shows the latch circuit of the current gear switching circuit according to the embodiment of the present invention;

FIG. 4 is a circuit diagram of the first switch unit of the current gear switching circuit according to the embodiment of the present invention;

Fig. 5 is a circuit diagram of the second switch unit of the voltage gear switching circuit according to the embodiment of the present invention;

FIG. 6 is a schematic block diagram of a DC/DC isolated power supply according to an embodiment of the present invention;

FIG. 7 is a circuit diagram of a DC/DC isolated power supply according to an embodiment of the present invention.

Detailed ways

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Please refer to Fig. 1, the calibrator of the data analysis field metering device disclosed in the present embodiment comprises a signal sampling module 1, a signal conditioning module 2, an A/D conversion module 3, an FPGA module 4, a DSP module 5 and an ARM module connected in sequence 6. In this embodiment, the A/D conversion module 3 includes a converter model of AD7656, the FPGA module 4 adopts a chip of the model XC3S200A and its peripheral circuits, and the DSP module 5 adopts a processor of the model TMS320F2812 and its peripheral circuits, ARM Module 6 adopts ARM processor and its peripheral circuits. FPGA module 4 is used to receive the voltage, current and pulse signals of the electric energy meter under test, and calculate the accumulated electric energy value, then transmit the voltage signal, current signal and accumulated electric energy value to DSP module 5, DSP module 5 according to the voltage signal and current The electric power parameter is calculated by the signal, and the standard electric energy value and the error value of the electric energy meter are calculated according to the accumulated electric energy value, and then the standard electric energy value and the error value are sent to the ARM module 6, and the ARM module 6 is connected with an expansion interface module and human-computer interaction Module, ARM module 6 is used for interface expansion, data display and storage, and human-computer interaction. The expansion interface module includes RS232 communication unit, RS485 communication unit, carrier communication unit, WIFI communication unit and USB communication unit connected to ARM module 6 respectively. unit, the human-computer interaction module includes a capacitive touch screen connected to the ARM module 6, and the ARM module 6 realizes human-computer interaction through the capacitive touch screen. Compared with the human-computer interaction mode of the display screen and keyboard of the existing calibrator, this implementation For example, the display screen ratio is larger, more data can be displayed, clearer and more convenient to operate.

Please refer to Figure 2-4, the signal conditioning module 2 includes a signal anti-aliasing filter 2-1 and a programmable gain amplifier 2-2 connected to each other, and the signal anti-aliasing filter 2-1 of this embodiment adopts an existing anti-aliasing filter The aliasing filter, the signal sampling module 1 includes a current mutual inductance sampling circuit 1-3, a clamp meter sampling circuit 1-4 and a current gear switching circuit 1-6 connected to the input end of the signal anti-aliasing filter 2-1, The current mutual inductance sampling circuit 1-3 and the clamp meter sampling circuit 1-4 are respectively connected to the current gear switching circuit 1-6 through the switch circuit 1-5, and the switch circuit 1-5 can use a rotary switch or a key switch, The current gear switching circuit 1-6 is provided with 4 switching gears. In this embodiment, 5A current is used as the standard, and the standard points of the full scale of the 4 switching gears are respectively 1 times the gear current 5A and 4 times the gear current 1.25A ( 1/4 of 5A), 16 times block current 0.3125A (1/6th of 5A) and 64 times block current 0.0781A (1/64 of 5A). Compared with the existing two switching gears, this embodiment further refines the measurement unit value of the current, which is beneficial to improve the accuracy of small signal measurement. The current gear switching circuit 1-6 comprises a microprocessor U31, a latch U32 and a first switch unit connected in sequence, and the microprocessor U31 is also connected with the DSP module 5, and the microprocessor U31 of the present embodiment adopts the model AT89C2051 chip, the latch U32 uses a chip with a signal of 74HC595, and the first switch unit includes a first switch chip U40 with at least four channels, a first voltage divider circuit 1-61, a first operational amplifier U16 and a second operational amplifier U17 , the first switch chip U40 adopts a four-way switch (U40A, U40B, U40C and U40D) of the model ADG1334BRSZ, the non-inverting input terminal of the second operational amplifier U17 is connected with the switch circuit 1-5, and the inverting input terminal of the second operational amplifier U17 The input end is grounded through the resistor R50, the output end of the second operational amplifier U17 is connected to the signal anti-aliasing filter 2-1, the first voltage divider circuit 1-61, the first switch chip U40 and the first operational amplifier U16 are sequentially connected and The feedback loop of the second operational amplifier U17 is formed, and the control terminal of the first switch chip U40 is connected with the latch U32. The first voltage divider circuit 1-61 comprises resistance R109, resistance R59, resistance R60, resistance R61 and resistance R68 that are connected in sequence and have an accuracy value of 0.05%. The present embodiment adopts precision resistances with an accuracy value of 0.05%. The accuracy of each gear of the first voltage divider circuit 1-61, thereby improving the accuracy of sampling current.

The program-controlled gain amplifier 2-2 of this embodiment adopts the CMOS analog multiplexer of model OP07, and the program-controlled gain amplifier 2-2 has 4 built-in differential channels, and is used to provide 1 times, 4 times, 16 times and 64 times of gain , the 4 differential channels of the program-controlled gain amplifier 2-2 are adapted to the 4 switching gears respectively, and can perform secondary amplification on the sampling current, and the gain error and distortion are small. The DSP module 5 is also connected with the current gear switching circuit 1-6 and the program-controlled gain amplifier 2-2 respectively, and the DSP module 5 can perform gear switching control and control on the current gear switching circuit 1-6 according to the sampling current of the current sampling circuit The programmable gain amplifier 2-2 performs gain selection and controls the programmable gain amplifier 2-2 to amplify the sampling current. According to the size of the sampling current signal, the gears are automatically switched and the appropriate gain is selected, which is beneficial to reduce the difficulty of small signal measurement and improve the measurement accuracy.

Please refer to FIG. 1 and FIG. 5, the signal adopting module also includes a voltage sampling circuit 1-1 and a voltage gear switching circuit 1-2, and the voltage gear switching circuit 1-2 includes a second switch unit connected to the latch U32, The second switch unit includes a second switch chip 37 of at least four channels, a second voltage divider circuit 1-61, a third operational amplifier U8 and a fourth operational amplifier U9, and the second switch chip U37 adopts a four-way switch model ADG1334BRSZ (U37A, U37B, U37C and U37D), the voltage gear switching circuit 1-2 is provided with 4 switching gears, among which the resistor R108, resistor R38, resistor R39, resistor R40 and resistor R47 all adopt the precision value of 0.05%. resistance, which is beneficial to improve the accuracy of voltage measurement.

For the specific circuit structures of the current mutual inductance sampling circuit 1-3 and the voltage sampling circuit 1-1 in this embodiment, reference may be made to the prior art.

Please refer to Fig. 6, the on-the-spot calibrator of the present embodiment also comprises the DC/DC isolation power supply that is connected with signal sampling module 1, signal conditioning module 2, FPGA module 4, DSP module 5 and ARM module 6 respectively, DC/DC isolation The power supply includes a controllable switch unit 7-1, an isolation and transformation unit 7-2, and a voltage output unit 7-3 connected in sequence, and the voltage output unit 7-3 includes a step-down regulator unit 7-31 for outputting the first voltage And the rectification and filtering unit 7-32 for outputting the second voltage, the isolation and transformation unit 7-2 is connected to the control terminal of the controllable switch unit 7-1 through the control logic unit 7-4.

Please refer to Fig. 7, the control logic unit 7-4 and the controllable switch unit 7-1 are integrated in a DC/DC control chip U2, the model of the DC/DC control chip U2 is LT3439EFE, and the isolation transformer unit 7-2 adopts The high-frequency transformer T1 of two sets of secondary windings, the first secondary winding of the high-frequency transformer T1 is connected to the step-down voltage stabilizing unit 7-31, and the second secondary winding of the high-frequency transformer T1 is connected to the voltage output unit 7-3 . In this embodiment, a high-frequency transformer T1 is used to completely insulate the primary winding from the secondary winding, and also isolate the input loop from the output loop. In addition, the working frequency of the transformer of this embodiment is high (500KHz), the volume of the magnetic core is small, and the high-frequency loss of the magnetic core is used to prevent the high-frequency clutter from entering the control circuit, and the anti-interference ability of the circuit is improved. Ensure the stability of the field calibrator circuit system.

The step-down voltage stabilizing unit 7-31 includes a voltage stabilizing chip U1, and the input end of the voltage stabilizing chip U1 is connected with a first filter 7-33, and the first filter 7-33 includes tantalum capacitors E1 and C2 connected in parallel, stabilizing The output terminal of the pressing chip U1 is connected with a second filter 7-34, the second filter 7-34 includes an LC filter circuit made up of an inductor L1, a tantalum capacitor E2 and a capacitor C3, and the rectification filter unit 7-32 includes a diode D5 , D6, D7 and D8 form the rectifier bridge and the third filter 7-35 and the fourth filter 7-36 connected with the rectifier bridge, diodes D5, D6, D7 and D8 adopt Schottky diodes, Schottky diodes The leakage current is small, which is conducive to reducing the output ripple. The third filter 7-35 includes a capacitor C5 and a tantalum capacitor E5 connected in parallel, and the fourth filter 7-36 includes a tantalum capacitor E6 and a capacitor C8 connected in parallel. , The leakage current of the tantalum capacitor is small, which is beneficial to reduce the output ripple and can significantly improve the power supply efficiency.

The above descriptions are only preferred embodiments of the present invention, and the present invention is not limited to the above-mentioned embodiments, as long as they achieve the technical effects of the present invention by the same means, they should all belong to the protection scope of the present invention. Various modifications and changes may be made to the technical solutions and/or implementations within the protection scope of the present invention.

Claims (8)

1. Data analysis on-site measurement device calibrator, including signal sampling module (1), signal conditioning module (2), A/D conversion module (3), FPGA module (4), DSP module (5) and ARM module (6), is characterized in that: also comprises and respectively with described signal sampling module (1), described signal conditioning module (2), described FPGA module (4), described DSP module (5) and described The DC/DC isolated power supply connected to the ARM module (6), the signal conditioning module (2) includes an interconnected signal anti-aliasing filter (2-1) and a programmable gain amplifier (2-2), and the signal sampling The module (1) includes a current gear switching circuit (1-6) connected to the input end of the signal anti-aliasing filter (2-1), and the current gear switching circuit (1-6) is provided with at least four To switch gears, the DSP module (5) is also connected to the current gear switching circuit (1-6) and the program-controlled gain amplifier (2-2) respectively, and is used to control the current gear switching circuit (1-6) to perform gear shifting. bit switching and controlling the programmable gain amplifier (2-2) for signal amplification. 2. The data analysis field measuring device calibrator as claimed in claim 1, is characterized in that: described signal sampling module (1) also comprises current mutual inductance sampling circuit (1-3) and clamp meter sampling circuit (1-4 ), the current mutual inductance sampling circuit (1-3) and the clamp meter sampling circuit (1-4) are respectively connected to the current gear switching circuit (1-6) through a switch circuit (1-5). 3. The data analysis site metering device calibrator as claimed in claim 2, characterized in that: said current gear switching circuit (1-6) comprises a microprocessor U31, a latch U32 and a first A switch unit, the microprocessor U31 is also connected with the DSP module (5), the first switch unit includes a first switch chip U40 of at least four channels, a first voltage divider circuit (1-61), a first operational amplifier U16 and the second operational amplifier U17, the noninverting input terminal of the second operational amplifier U17 is connected with the switch circuit (1-5), the inverting input terminal of the second operational amplifier U17 is grounded through the resistor R50, the second operational amplifier U17 The output terminal is connected with the signal anti-aliasing filter (2-1), and the first voltage divider circuit (1-61), the first switch chip U40 and the first operational amplifier U16 are connected in sequence to form the second operational amplifier U17. In the feedback loop, the control terminal of the first switch chip U40 is connected to the latch U32. 4. The calibrator of data analysis field metering device as claimed in claim 3, is characterized in that: described first voltage divider circuit (1-61) comprises resistance R109, resistance R59 that are connected successively and precision value is 0.05%. , resistor R60, resistor R61 and resistor R68. 5. The calibrator of data analysis site metering device as claimed in claim 1 or 3, characterized in that: said programmable gain amplifier (2-2) has 4 built-in differential channels, and is used to provide 1 times, 4 times, 16 times and gains of 64 times. 6. The on-site calibration instrument according to claim 1, characterized in that: the DC/DC isolated power supply comprises a controllable switch unit (7-1), an isolated transformer unit (7-2) and a voltage The output unit (7-3), the voltage output unit (7-3) includes a step-down regulator unit (7-31) for outputting the first voltage and a rectification and filtering unit (7-32) for outputting the second voltage , the isolated transformer unit (7-2) is connected to the control terminal of the controllable switch unit (7-1) through the control logic unit (7-4). 7. The calibrator of data analysis field metering device as claimed in claim 6, characterized in that: said control logic unit (7-4) and said controllable switch unit (7-1) are integrated in a DC/DC Inside the control chip U2, the isolation transformer unit (7-2) adopts a high-frequency transformer T1 comprising two sets of secondary windings, and the first secondary winding of the high-frequency transformer T1 is connected to the step-down voltage stabilizing unit (7-2). 31) connection, the second secondary winding of the high frequency transformer T1 is connected to the voltage output unit (7-3). 8. The field metering device calibrator for data analysis as claimed in claim 7, is characterized in that: the step-down voltage stabilizing unit (7-31) comprises a voltage stabilizing chip U1, and the input terminal of the voltage stabilizing chip U1 is connected with a first A filter (7-33), the first filter (7-33) includes tantalum capacitors E1 and C2 connected in parallel, the output end of the voltage stabilizing chip U1 is connected with a second filter (7-34), the second Filter (7-34) comprises the LC filter circuit that is made up of inductance L1, tantalum capacitor E2 and capacitor C3, and described rectification filter unit (7-32) comprises the rectifier bridge that is made up of diode D5, D6, D7 and D8 and with The third filter (7-35) and the fourth filter (7-36) connected by the rectifier bridge, the third filter (7-35) includes capacitor C5 and tantalum capacitor E5 connected in parallel, the fourth filter ( 7-36) includes a tantalum capacitor E6 and a capacitor C8 connected in parallel.