CN2160915Y - Digital watt-hour meter for multiple consumers - Google Patents

Abstract

The utility model relates to a digital watt-hour meter for multiple consumers to measure electrical energy. The utility model makes an SCM as the core and is provided with a plurality of sampling switch circuits, a peak-value sampling holder circuit, an A/D switch circuit, a phase difference measure circuit, a storage circuit and a keyboard display circuit. The utility model can simultaneously measure the quantity of electricity usage for fifty consumers. The digital watt-hour meter for multiple consumers can display eight digits, and the accumulative quantity of electricity usage or the paying amount of electric charge of each consumer. The digital watt-hour meter for multiple consumers can display intensively, and the content is displayed by key-press switch. The utility model which is no need to have any spare electrical source and can keep the data reliably after power off has the advantages of precise and reliable measure and long service life, and the digital watt-hour meter for multiple consumers is suitable for the electrical energy measure of building cell typed houses and other places with dense houses.

Description

Digital watt-hour meter for multiple consumers

This utility model is one and relates to multi-user's electric energy measurement, particularly is applied to the residential houses electric energy measurement, with the multi-user digital watt-hour meter of each the user's accumulative total power consumption of digital form centralized displaying and the number of should paying tariff.

The mechanical type watt-hour meter that all is based on principle of induction that electric energy measurement is adopted usually, this instrument has mechanical wearing terrain, life-span weak point, poor accuracy, shortcoming such as sensitivity is low, overload capacity is poor, poor stability, counting cost by gas meter are numerous and diverse, D86 series watt-hour meter, though aspect overload capacity, aspect increasing the service life, improving to some extent aspect the sensitivity improving, but still having above-mentioned inherent shortcoming based on the mechanical type watt-hour meter of principle of induction.

The employing microcomputer technology is disclosed among the Chinese patent CN104344A, by the multiloop timing sampling, utilize adopt voltage, the mode that current average multiplies each other, calculate power consumption.This mode requires the sampling period enough short, and therefore sampling takies a lot of machine times, is difficult to the more sampling ways of expansion; after the power down, data protection requires that standby power supply is arranged, and has increased the maintenance of instrument like this; the non-loss of data, reliability are relatively poor, are unfavorable for popularizing use.

The purpose of this utility model provides a kind of digital watt-hour meter, and it is applicable to multi-user's electric energy measurement, with each user's of digital form centralized displaying accumulative total power consumption and should pay electricity charge number.It need not any standby power supply, can keep data not lose, accurately and reliably.

Mains supply generally is the 50Hz sine wave, therefore can adopt following formula to calculate the power consumption on j road.

Pj＝

U _mi·I _mij·COSφ _ij·R _i·△T

Wherein j is sampling road number, and i refers to sample for the i time, and △ T is the cycle in sampling time, Um-voltage peak, Imj-user (j) load current peak value, COS φ-power factor, R-quantization parameter.The present invention promptly realizes by this principle of work.This digital kilowatt-hour meter detects holding circuit, range automatic switching circuit, phase difference detecting circuit, A/D change-over circuit, single chip circuit, memory circuit and keyboard display circuit by: power supply, multi-channel sampling switch, peak value and forms.

The multi-channel sampling switch circuit, by single chip circuit control, each sampling period is when beginning, by the computer control multi-channel sampling switch, each road sampling channel of order gating is because conductor resistance is very little, so voltage sample can be with a point sampling, the voltage sampling part can obtain by electric resistance partial pressure.Current sampling can be obtained by current transformer or shunt resistance form.

Peak sampling hold circuit, after a certain sampling channel of computer control gating, the computer starting phase difference detecting circuit, simultaneous computer set peak-holding circuit enters the peak value hold mode, under this state, just keep in case the peak value sampling retainer samples peak signal, and send signal to computing machine immediately.In this course, at peak value sampling retainer input end, input signal is compared with the holding signal of retainer, and it is ignored less than the input signal of peak value, and always tries hard to be kept above the peak signal in the retainer.This circuit promptly when electric frequency 50Hz, only use the 20ms time in the time of a sine wave period, can be exactly with the peak value sampling and the maintenance of sine wave.Can realize multi-channel sampling at a high speed so utilize this circuit.In two seconds, can finish sampling and data processing more than 50 tunnel.

After computing machine receives the peak signal of peak value sampling retainer, promptly start the A/D change-over circuit.

Phase detecting circuit is made up of the time/counter of two zero-detection comparers and single-chip microcomputer, and computing machine obtains phase differential by calculating by the mistiming between two zero cross signals, and by the look-up routine instruction, checks in corresponding COS φ value.

Peak signal entered Automatic Range-changing Circuit before entering the A/D circuit conversion, by Automatic Range-changing Circuit, peak signal is carried out the amplification of different amplification, can improve the resolution of A/D change-over circuit like this, improved measuring accuracy.The input end of range change-over circuit output termination A/D change-over circuit.After the computer starting A/D conversion, promptly carry out digital-to-analog conversion.Transformation result behind digital filtering, is sent into memory cell.Like this computing machine can according to adopt Um, given △ T value in Im value and the program, the R value is carried out data processing operation, obtain each the road accumulative total power consumption in the △ T time interval, with this power consumption and former cumulative amount addition, and storage, promptly finish the sampling of electric energy, accumulative total and store function.

Data memory is used to store the accumulative total power consumption in each loop, and its minimum division value is 0.1 kilowatt hour.0.1 the value that kilowatt hour is following; add up computing in the memory in single-chip microcomputer; when 0.1 kilowatt hour carry takes place when; just enter the data memory cumulative calculation; when power-down conditions takes place; the above data of 0.1 kilowatt hour will obtain reliably protecting in each loop; 0.1 the following data of kilowatt hour will be lost; for reducing the data loss loss that power down causes; in program, adopted intermediate value to give the technology of putting; promptly in the initialize routine when re-powering with the numerical value of intermediate value 0.05 kilowatt hour of 0-0.1 kilowatt hour; return in the former memory as the lost data intermediate value, according to Probability Principles: because of the electric weight of power down loss between the 0-0.1 kilowatt hour, along with this numeral of increase of power down number of times should be tending towards 0.05 kilowatt hour gradually; we give recovery numerical value 0.05 kilowatt hour of putting, and just in time satisfy this principle.Along with the power down number of times increases, the loss of using this mode that power down will be caused goes to zero.From another angle, during power failure, the electric weight numeral that lose in each loop also is tending towards 0.05 kilowatt hour according to a plurality of loops of Probability Principles average between 0-0.1 kilowatt.So when we give the restore data of putting each loop when re-powering is 0.05 kilowatt hour, and total system is gone to zero by the data degradation that power failure causes.Simultaneously, along with the power down number of times increases, the data degradation that each loop itself is caused by power down also goes to zero.This is the important technology feature of this instrument, adopt this technology after, can remove standby power supply, and don't the accuracy of measurement of dead electricity kilsyth basalt.

Single-chip microcomputer is the core of this instrument, and it controls sampling switch circuit, peak value sampling retainer circuit, and A/D change-over circuit, phase difference detecting circuit, memory and keyboard-display circuit work, it produces the sampling period signal, the line data computing of going forward side by side storage.

Keyboard and display circuit are finished the work of demonstration and switching display content, and display has eight LED numbers, and wherein two show the way code names, and all the other 6 show the accumulative total power consumptions and should pay electricity charge number.Displaying contents and demonstration way code name can switch by button, have three buttons, and one of them button switching display content, all the other two buttons are used for switching demonstration way code name.

Advantage of the present utility model and good effect:

1, can substitute traditional mechanical formula watt-hour meter 50-100 piece with a machine, table look-up and intuitively be convenient to management, safety, reliable.

2, resolution height, measuring accuracy is higher.

3, long service life, easy to maintenance, do not need standby power supply.

4, with low cost, a little higher than a considerable amount of traditional mechanical formula watt-hour meter of its price, but be lower than D86 type mechanical type watt-hour meter.

5, have the electricity charge of demonstration function, charge is convenient.

6, can expand other function, as: double fee rate charge, security alarm etc.

7, can stop the phenomenon of sneaking current.

As above-mentioned the utility model, have good economic benefit and social benefit, be the regeneration product of other watt-hour meter, it is best suited for civilian modular dwelling house, reaches the dwelling house use under the concentrated environment of resident family.

The detailed description of specific embodiments: (Fig. 6) be overall diagram.

Fig. 1 is multi-channel sampling switch circuit and peak-holding circuit circuit.

The multi-channel sampling switch circuit is by cmos analog switch 4067(U1), form.Peak value sampling retainer circuit, by sampling holder (U2), voltage comparator (U3), dual input Sheffer stroke gate (U4), capacitor C 11 is formed.It is work like this, when computing machine sends sample command, the sampling switch of each passage of computing machine order gating, make the sampled signal (INO) of conducting enter the common signal end of input channel, it is high level that computing machine is put Pzl, start phase difference detecting circuit simultaneously, make it to enter sampling phase difference signal state.Signal INO connects the input end of retainer, receive the negative terminal of voltage comparator simultaneously, and the output signal IN+O of sampling holder connects the anode of U3, and INO and IN+O compare at U3, when INO＞IN+O, the voltage comparator output low level, Pz7 is a high level, and sampling holder is in sample states, and U3 is output as high level when INO+＞INO, at this moment Pz7 is a low level, and sampling holder is in hold mode.Signal peak will effectively be kept.When COMPUTER DETECTION when Pz7 is low level, start the A/D change-over circuit.

Fig. 2, be Automatic Range-changing Circuit and A/D change-over circuit, Automatic Range-changing Circuit is by amplifier (U5), multiway analog switch (U6), voltage comparator (U7), potentiometer W1, W2 form, and the A/D change-over circuit is by A/D chip 0804(U8) and the reference data voltage generator circuit form.

Signal IN+O connects amp.in, and voltage comparator (U7) negative terminal, the comparison of IN+O and reference voltage is by the enlargement factor of the automatic control amplifier of state of the output terminal of U7, reach the effect of automatic conversioning broad with this, potentiometer W1, W2 are used to adjust enlargement factor.The present embodiment only is provided with second gear range conversion, and reference voltage is 0.22V, and when IN+O＜0.22V, enlargement factor is 15 times, and during greater than 0.22V, enlargement factor is 3 times, has improved the minimum resolution of sampling and A/D conversion like this.When nominal load current was 10A, the resolution of this table can reach 10mA, had improved 4-5 doubly than mechanical type instrument.The class that increases range conversion behind some elements also can increase, through the signal after the amplification of automatic range amplifying circuit, be connected on the input end of A/D converter, carry out A/D conversion under computer control, transformation result is carried out digital filtering, with measure voltage signal values, deposit the voltage signal values memory cell in, with the current signal value of measuring, calculate by following formula, P=UmImCOS φ R △ T wherein COS φ is detected behind the phase difference value to table look-up by program by phase difference detecting circuit and obtains.R, △ T are given by program.

Fig. 3 is single-chip microcomputer and memory circuit, and single-chip microcomputer adopts 8032 chips (Uo), and crystal oscillator 6MHZ, memory are 2732(U9), data memory adopts 2817A(U10).

The 8032nd, the core of entire circuit, it controls multi-channel sampling switch, peak value sampling retainer, A/D conversion and phase difference detecting circuit, show and keyboard circuit work, produce the periodic sampling order, carry out data processing, reach work such as storage, the warning of excess limit, 2732 is memory under program, and 2817A is a data memory, through the sampled value of Computer Processing, 0.1 the above value of kilowatt hour all deposits in the memory, the storage zone is corresponding with the sampling way.To stay in the memory in the single-chip microcomputer less than the value of 0.1 kilowatt hour, the above data of 0.1 kilowatt hour will effectively be preserved when cutting off the power supply like this.

Fig. 4 is phase difference detecting circuit, is made up of the T2 time/counter of two voltage comparators (U11, U12) and single-chip microcomputer.Voltage signal is directly received the voltage interface end by voltage divider, and current signal is received the current interface end by the common port of sampling channel.Set T2 time/counter in the time of a certain current channel sampling switch of computing machine gating, start the phase-detection program, as U(t) during zero passage, undersuing of voltage comparator output, send interrupt request by P1.0 to CPU, CPU responds interrupt request, T2 timing/counter is placed time status, T2 picks up counting, in case as i(t) during zero crossing, produce a undersuing again, send interruption by P1.1 to CPU, CPU responds interrupt request, and the count value of T2 is caught in the computer memory.This time promptly is the phase difference value of electric current and voltage.Computing machine is tabled look-up by COS φ handling procedure and is tried to achieve corresponding COS φ value, and deposits corresponding memory cell confession data processor in and call.

Fig. 5 is a partly circuit diagram of display, keyboard, adopts 8279(U13) keyboard display managing chip and driver 7445(U14), reverse driven 7407(U15) and, and 8 bit digital show the LED pipe, three buttons and resistor group R10.Computing machine manages by 8279 pairs of displaying contents and keyboard.Show 8 LED, wherein two show the way code name, and all the other 6 show the accumulative total power consumption, or demonstration should be paid electricity charge number.Show the way code name, and displaying contents switches by button.Can remove the charge number by button.

Embodiment can also be used 8098 single-chip microcomputers, can save an A/D conversion chip like this, and improves resolution.

Claims (5)

1, a kind of multi-user digital formula watt-hour meter, it comprises power supply, sampling hold circuit, range change-over circuit, phase difference detecting circuit, the data-storing circuit, keyboard and display circuit, single chip circuit, it is characterized in that it comprises peak value sampling retainer circuit, Automatic Range-changing Circuit, phase difference detecting circuit, EEPROM data memory circuit.

2, watt-hour meter according to claim 1 is characterized in that peak sampling hold circuit is made up of single-chip microcomputer, sampling holder and amplifier.

3, watt-hour meter according to claim 1 is characterized in that phase difference detecting circuit is made up of the time/counter of two zero-detection comparers and single-chip microcomputer.

4, watt-hour meter according to claim 1 is characterized in that the data memory circuit wipes memory by the EEPROM electricity and constitute.

5, watt-hour meter according to claim 1 is characterized in that Automatic Range-changing Circuit by amplifier, and multicircuit switch and voltage comparator are formed.

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