CN202256481U

CN202256481U - Alternating current (AC) digital voltmeter

Info

Publication number: CN202256481U
Application number: CN201120346545XU
Authority: CN
Inventors: 贾保军
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-09-16
Filing date: 2011-09-16
Publication date: 2012-05-30
Anticipated expiration: 2021-09-16

Abstract

The utility model discloses an alternating current (AC) digital voltmeter. The voltmeter comprises a keyboard, a voltage-dividing sampling circuit, an analog-to-digital (A/D) converter, a central processing unit (CPU) with fast Fourier transform (FFT) software, a liquid crystal display (LCD), a communication module and a programmable memory, wherein the output end of the voltage-dividing sampling circuit is connected with the corresponding input end of the A/D converter; the A/D converter is bidirectionally connected with the CPU; the output end of the CPU is connected with the corresponding input end of the LCD; the CPU is connected with the programmable memory through a data bus; the voltage-dividing sampling circuit consists of a phase A circuit, a phase B circuit and a phase C circuit which are the same; and the phase A circuit comprises resistors R1, R2, R3 and R4 and capacitors C1 and C2. The voltmeter is provided with the programmable memory and the CPU with the FFT software, so that the voltmeter has data storage and harmonic analysis functions, voltage and the historical data of a harmonic component can be obtained at any time according to the requirement, the condition of electric energy quality is convenient to query, and the voltmeter is convenient to use.

Description

AC digital voltmeter

Technical field

The utility model relates to a kind of AC digital voltmeter, especially a kind of AC digital voltmeter with data storage harmonic analytic function.

Background technology

Digitized voltage table in the market mainly adopts analog to digital conversion (A/D); With analog-signal transitions is digital quantity, is transported to processing unit (CPU) then, outputs to charactron through after the computational analysis; Be transported to COM1 when having, data are passed to computing machine or other control system.The digitized voltage table of this form has certain shortcoming: 1) data measured can not and be reappeared in the storage of this machine; The same with needle dc voltmeter; Just show instantaneous value, before needs are understood, during the magnitude of voltage situation of certain period, do not have the data that supply to inquire about; 2) qualitative character of the voltage of surveying can not be provided, harmonic component for example, the relevant quality of power supply standard code of country the ultimate value of harmonic component in the voltage; But general electricity consumption occasion does not have corresponding techniques means and equipment again, can not accomplish to observe at any time and record, and uses instrumentation to measure; Wiring is complicated; Need the professional to operate, data measured also needs special software to analyze, and it is very high therefore to measure cost.

The utility model content

The technical matters that the utility model will solve provides a kind of AC digital voltmeter with data storage harmonic analytic function.

For solving the problems of the technologies described above; The technical scheme that the utility model is taked is: a kind of AC digital voltmeter, and its gordian technique is: it comprises keyboard, pressure sampling circuit, analog to digital converter U1, central processing unit U2, LCD display, communication module and programmable storage U3 that Fourier series is decomposed software is housed; The output terminal of said pressure sampling circuit is connected with the respective input of analog to digital converter U1; Said analog to digital converter U1 is connected with central processing unit U2 is two-way; The output terminal of central processing unit U2 is connected with the respective input of LCD display, and said central processing unit U2 is connected with programmable storage U3 through data bus; Said pressure sampling circuit is made up of with the identical circuit of C phase three-phase A phase, B mutually; Wherein A comprises resistance R 1, R2, R3, R4 and capacitor C 1, C2 mutually; The VA of said A phase, VN end connects 3 pin, 4 pin of analog to digital converter U1 respectively successively through resistance R 1 and R2, R3 and R4; Said capacitor C 1 is connected between 3 pin and ground of analog to digital converter U1, and said capacitor C 2 is connected between 4 pin and ground of analog to digital converter U1.

The model of above-mentioned central processing unit U2 is STM32F103RET6; The model of said programmable storage U3 is AT45DB081DSV.

Above-mentioned analog to digital converter U1 adopts three-phase electrical energy computation chip, and its model is ATT7022D.

Above-mentioned communication module model is RSM485; The model of said LCD display is HG12864-15AF.

36 pin of above-mentioned central processing unit U2 connect 1 pin of programmable storage; 34 pin of said central processing unit U2 connect 2 pin of programmable storage U3; 33 pin of said central processing unit U2 connect 4 pin of programmable storage U3, and 35 pin of said central processing unit U2 connect 8 pin of programmable storage U3.

Adopt the beneficial effect that technique scheme produced to be: the utility model can be preserved the historical data of voltage and harmonic voltage 365 days through the programmable storage that is provided with; Data when more than 365 days are overflowed automatically; So just can transfer the historical data of voltage as required at any time; LCD display is the waveform of display voltage and the histogram of harmonic voltage synchronously, so that inquiry quality of power supply situation; Fourier series is installed in the central processing unit decomposes software, can obtain the harmonic component in the signal, so that check quality of voltage; The utility model needn't rely on background computer to store data as in the past, and was very easy to use.

Description of drawings

Fig. 1 is that the hardware of the utility model connects block diagram;

Fig. 2 is the circuit theory diagrams of the utility model;

Fig. 3 is the software flow block diagram of the utility model

Fig. 4 is the voltage history record diagram;

Fig. 5 is the voltage harmonic histogram;

Fig. 6 is the enlarged drawing of A portion among Fig. 2;

Fig. 7 is the enlarged drawing of B portion among Fig. 2.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is done further detailed explanation.

Referring to accompanying drawing 1, accompanying drawing 2, accompanying drawing 3, accompanying

drawing

6 and 7, the utility model comprises keyboard, pressure sampling circuit, analog to digital converter, central processing unit U2, LCD display, communication module and programmable storage U3 that Fourier series is decomposed software (FFT) is housed; The output terminal of said pressure sampling circuit is connected with the respective input of analog to digital converter; Said analog to digital converter U1 is connected with central processing unit U2 is two-way; The output terminal of central processing unit U2 is connected with the respective input of LCD display, and said central processing unit U2 is connected with programmable storage U3 through data bus; Said pressure sampling circuit is made up of with the identical circuit of C phase three-phase A phase, B mutually; Wherein A comprises resistance R 1, R2, R3, R4 and capacitor C 1, C2 mutually; The VA of said A phase, VN end connects 3 pin, 4 pin of analog to digital converter U1 respectively successively through resistance R 1 and R2, R3 and R4; Said capacitor C 1 is connected between 3 pin and ground of analog to digital converter U1, and said capacitor C 2 is connected between 4 pin and ground of analog to digital converter U1.B is mutually the same with A with the circuit structure of C phase mutually, and just the label of electric elements is different, and signal all is the difference input.Wherein, be provided with dc bias circuit in the peripheral circuit of analog-to-digital conversion module, like resistance R 5, the resistance R 6 of A in mutually.

Wherein, the model of the U2 of central processing unit described in the figure is STM32F103RET6; The model of said programmable storage U3 is AT45DB081DSV.Said analog to digital converter U1 adopts three-phase electrical energy computation chip, and its model is ATT7022D.Said communication module model is RSM485; The model of said LCD display is HG12864-15AF

36 pin of said central processing unit U2 connect 1 pin of programmable storage U3; 34 pin of said central processing unit U2 connect 2 pin of programmable storage U3; 33 pin of said central processing unit U2 connect 4 pin of programmable storage U3, and 35 pin of said central processing unit U2 connect 8 pin of programmable storage U3.

Referring to accompanying drawing 2; Three-phase sampled voltage Ua, Ub, Uc signal are connected with the input end of analog to digital converter U1 respectively; Analog to digital converter U1 adopts 19 A/D converter ATT7022D of the bipolar input of six passages chip; Its analog quantity with voltage converts digital quantity into, delivers to central processing unit U2 then and carries out computing.Central processing unit U2 is circumscribed with real-time clock integrated circuit, RSM485 communication module and external key interface.The digital signal output end of central processing unit U2 is connected with LCD display.Connect through SPI between central processing unit U2 and the programmable storage U3, central processing unit U2 calculates through the real-time analysis of FFT software, draws the amplitude of first-harmonic and 2～25 subharmonic.Central processing unit U1 is kept at measuring parameter among the programmable storage U3 through latch on the one hand, and it stores voltage and relevant harmonic voltage value; Export each measuring parameter to LCD display (128*64) on the other hand; Show through display screen, when the outside has data transmission to require, to 485 communication modules transmission data; Promptly link to each other with PC through the RSM485 communication module; Can be correlated with to voltage table is provided with and data transmission, and continuous data is sent on the PC, is managed by the PC management software.The RSM485 interface can connect 128 voltage tables at most, and communication distance reaches 1.5 kilometers.

Referring to accompanying drawing 4, during work, the form of presentation of magnitude of voltage historical data adopts graphics mode; The longitudinal axis is a voltage effective value; By the amplitude scale of volt (V) or kilovolt (kV), transverse axis is 24 hours a time scale, and magnitude of voltage carries out the integral point time recording according to amplitude and time.When the 24th hour finishes, deposit the data of 24 hour records in programmable storage U3.Before needs are checked, during the voltage history data of some day, through the inquiry of historical data function, confirm the date through the perpetual calendar in the machine, the data of this day promptly are presented on the screen.When transferring historical data, do not influence the normal measurement and the record of instrument.Historical data coexistence storage 365 days, the mode of the storage of taking to circulate, i.e. storage is full after 365 days, when nearest 24 hour datas deposit in, covers first data of 24 hours.

Referring to accompanying drawing 5; When the digital quantity after the analog to digital conversion being carried out the first-harmonic metering; By central processing unit the RMS value is carried out fast Fourier progression (FFT) conversion; Obtain the harmonic component in the signal, the utility model can carry out the entire spectrum analysis to 2～25 subharmonic, promptly odd number is all carried out frequency analysis with even harmonics.2～25 subharmonic values show on liquid crystal display with the form of histogram; The longitudinal axis is represented the content of harmonic wave by percentage; Transverse axis is represented 2-25 subharmonic number of times, and the content of harmonic wave is represented (HR%) with the form of histogram, shows fundamental voltage value (V on the display screen simultaneously; And total percent harmonic distortion (THDv%) of analystal section (2-25) kV).The SF of data is 3.2K/ second, when 24 hours finish, instrument calculate in 24 hours 3 mutually in the big value of 95% probability of each harmonic, minimum value and mean value deposit programmable storage U3 in.Before needs are checked, during the harmonic data of some day, through the inquiry of historical data function, confirm the date through the perpetual calendar in the machine, the various data of this day promptly are presented on the screen.When transferring historical data, do not influence the normal measurement and the record of instrument.Historical data coexistence storage 365 days, the mode of the storage of taking to circulate, i.e. storage is full after 365 days, when nearest 24 hour datas deposit in, covers first data of 24 hours.

To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the utility model.Multiple modification to these embodiment will be conspicuous concerning those skilled in the art, and defined General Principle can realize under the situation of spirit that does not break away from the utility model or scope in other embodiments among this paper.Therefore, the utility model will can not be restricted to these embodiment shown in this paper, but will meet and principle disclosed herein and features of novelty the wideest corresponding to scope.

Claims

1. AC digital voltmeter is characterized in that: it comprises keyboard, pressure sampling circuit, analog to digital converter U1, central processing unit U2, LCD display, communication module and programmable storage U3 that Fourier series is decomposed software is housed; The output terminal of said pressure sampling circuit is connected with the respective input of analog to digital converter U1; Said analog to digital converter U1 is connected with central processing unit U2 is two-way; The output terminal of central processing unit U2 is connected with the respective input of LCD display, and said central processing unit U2 is connected with programmable storage U3 through data bus; Said pressure sampling circuit is made up of with the identical circuit of C phase three-phase A phase, B mutually; Wherein A comprises resistance R 1, R2, R3, R4 and capacitor C 1, C2 mutually; The VA of said A phase, VN end connects 3 pin, 4 pin of analog to digital converter U1 respectively successively through resistance R 1 and R2, R3 and R4; Said capacitor C 1 is connected between 3 pin and ground of analog to digital converter U1, and said capacitor C 2 is connected between 4 pin and ground of analog to digital converter U1.

2. AC digital voltmeter according to claim 1 is characterized in that: the model of said central processing unit U2 is STM32F103RET6; The model of said programmable storage is AT45DB081DSV.

3. AC digital voltmeter according to claim 1 is characterized in that: said analog to digital converter U1 adopts three-phase electrical energy computation chip, and its model is ATT7022D.

4. AC digital voltmeter according to claim 1 is characterized in that: said communication module model is RSM485; The model of said LCD display is HG12864-15AF.

5. AC digital voltmeter according to claim 2; It is characterized in that: 36 pin of said central processing unit U2 connect 1 pin of programmable storage; 34 pin of said central processing unit U2 connect 2 pin of programmable storage U3; 33 pin of said central processing unit U2 connect 4 pin of programmable storage U3, and 35 pin of said central processing unit U2 connect 8 pin of programmable storage U3.