CN2919261Y

CN2919261Y - AC current and voltage measuring circuit adopting AC sampling

Info

Publication number: CN2919261Y
Application number: CN 200620056273
Authority: CN
Inventors: 宋益群
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-15
Filing date: 2006-03-15
Publication date: 2007-07-04
Anticipated expiration: 2016-03-15

Abstract

The utility model relates to an AC sampling AC current and voltage measuring circuit, comprising a sampling circuit, comparison circuit and a single chip microprocessor. The sampling circuit transform the AC signals to be measured in the return circuit into am AC signal output to be measured with fixed proportion. The comparison circuit measures the frequency of the signal to be measured and send them out to the single chip microprocessor to sample in which the A/D conversion convert the signal to be measured accordingly and send them to the CPU in the microprocessor which compare the frequency signal in the comparison circuit, decide the frequency of the AC signal sampling, calculate the AC signal and send out the result. The utility model samples directly with the advantages of real-time measurement, high accuracy, quick response, simple structure, low production cost and high efficiency.

Description

Adopt alternating current, the tension measuring circuit of AC sampling

1, technical field:

The utility model relates to the metering circuit of a kind of alternating current, voltage, relates in particular to a kind of alternating current of AC sampling, metering circuit of voltage of adopting.

2, background technology:

The instrument that tradition is used to measure alternating current parameter generally is to adopt electromagnetic type, electrodynamic type or electrostatic intrument to measure, its shortcoming is that intuitive is poor, and precision is low, function singleness, be subjected to the restriction of frequency harmonics, the AC signal of the bigger harmonic wave of degree of distortion do not had accuracy can say.

At present, comparatively Xian Jin measuring method is by a series of analog conversion circuit, with the corresponding direct current signal of AC signal conversion hysteria, again this direct current signal is carried out the A/D conversion, but such method still can not be measured accurately to the signal of wave form distortion, and because the accuracy meeting of analog chip reaches variation of temperature in time and drifts about, thereby stable poor, the real-time of measurement data also will be subjected to the influence of analog chip response speed.In the production practices of reality, higher, the complex circuit of the cost of products of this scheme.

3, summary of the invention:

In order to overcome the deficiencies in the prior art, the purpose of this utility model provides a kind of alternating current of AC sampling, metering circuit of voltage of adopting, and it makes the real-time of measurement good, the precision height of measurement by directly AC signal being sampled.

The utility model is achieved by the following technical solution: it comprises sample circuit, comparator circuit and single-chip microcomputer; Sample circuit is converted to the AC signal output to be checked that tool is determined proportionate relationship with the AC signal in loop to be checked; Comparator circuit is measured the frequency of described AC signal to be checked and this frequency signal is exported to and samples in the single-chip microcomputer; Be provided with the A/D change-over circuit in the single-chip microcomputer, the A/D change-over circuit carries out the A/D conversion to AC signal to be checked and exports the CPU of single-chip microcomputer to, CPU on the single-chip microcomputer is according to the frequency signal of comparator circuit input, and decision is calculated the size of AC signal and exported result of calculation the frequency of AC signal sampling.

The utility model is to be further improved by following technical solution:

Above-mentioned described sample circuit is made up of linear transform circuit and voltage reference circuit, linear transform circuit is converted into the ac voltage signal output to be checked that tool is determined proportionate relationship with the ac current signal in loop to be checked, the low level output terminal of linear transform circuit is connected with the reference voltage terminal of voltage reference circuit, so that the negative half-cycle signal of sample circuit output is more than zero point.

Above-mentioned described high level output terminal at sample circuit is connected with pressure limiting circuit, is controlled in certain scope in order to the magnitude of voltage with the high level output terminal of sample circuit.

Above-mentioned described single-chip microcomputer adopts the MSP430F series monolithic.

The utility model compared with prior art has following advantage: 1) directly AC signal is sampled, a complete signal period is delivered to the processor sampling, the real-time of measurement is good, the precision height of measurement; 2) utilize single-chip microcomputer that measured signal is handled, because the integrated level height of single-chip microcomputer, performance is strong, good stability, low in energy consumption, so the accuracy of measurement height of signal, and reaction velocity is fast, and can make circuit more simple, and production cost is lower, and efficient is higher.

4, description of drawings:

Below in conjunction with accompanying drawing the utility model is done detailed explanation:

Fig. 1 is a theory diagram of the present utility model;

Fig. 2 is the realization circuit diagram of a kind of preferred version of Fig. 1.

5, embodiment:

As shown in Figure 1 and Figure 2, the utility model comprises that it comprises sample circuit 1, comparator circuit 2 and single-chip microcomputer 3;

Sample circuit 1 is made up of linear transform circuit 11 and voltage reference circuit 12, linear transform circuit 11 is converted into the ac voltage signal output to be checked that tool is determined proportionate relationship with the ac current signal in loop to be checked, the low level output terminal of linear transform circuit 11 is connected with the reference voltage terminal VREF of voltage reference circuit 12, so that the negative half-cycle signal of sample circuit 1 output is more than zero point, this linear transform circuit 11 is by D.C mutual-inductor CT1, sampling resistor R4, current-limiting resistance R5 and capacitor C 1 are formed, also can adopt resistor voltage divider network to finish the conversion of voltage in the practical application, high level output terminals A CA at sample circuit 1 is connected with pressure limiting circuit 4, this pressure limiting circuit 4 is made up of schottky diode D1 and low-dropout regulator IC3, is controlled in certain scope in order to the magnitude of voltage with the high level output terminals A CA of sample circuit 1.

Comparator circuit 2 adopts the comparer of LM358 chip, the positive input terminal of LM358 comparer (5 pin) is connected with the high level output terminals A CA of sample circuit 1, the negative input end of LM358 comparer (6 pin) is connected with the low level output terminal of sample circuit 1, measures and frequency signal is exported to by the frequency to signal to be checked relatively among the CPU of single-chip microcomputer and sample;

The MSP430F135 single-chip microcomputer that single-chip microcomputer 3 is produced for Texas Instrument, have 12 A/D change-over circuits 31 in it, 31 pairs of signals to be checked of A/D change-over circuit carry out the A/D conversion and export among the CPU 32 of single-chip microcomputer 3, CPU 32 in the single-chip microcomputer 3 is according to the frequency signal of comparator circuit 2 inputs, decision is calculated the size of AC signal and is exported result of calculation the frequency of AC signal sampling.

The course of work of the present utility model is as follows: big alternating voltage, current signal, it is the AC signal of 2.5V that 12 linear transformations of process linear transform circuit become peak value, because the low level output terminal of linear transform circuit 12 is connected with the reference voltage terminal VREF of voltage reference circuit 13, wherein the magnitude of voltage of reference voltage terminal VREF is 1.2v (with respect to the ground of instrument power), select suitable sample resistance R4, put down in the place that just can make AC signal all be higher than system, so just guaranteed that a complete signal period gives the CPU on the single-chip microcomputer 3 32 samplings, the signal of LM358 comparer positive input terminal (5 pin) is greater than the signal of negative input end (6 pin) time, the output terminal of LM358 comparer (7 pin) is exported high level otherwise 7 pin output low levels, comparator circuit 2 output be square-wave signal PLUS with tested AC signal same frequency, this signal is got involved 36 pin of single-chip microcomputer 3, measure the frequency of this square-wave signal by the CPU on the single-chip microcomputer 3 32, so also just obtain the frequency of measured signal, according to this frequency, decision is to the frequency of AC signal sampling; The signal of this point of ACA is also received 5 pin of single-chip microcomputer 3 simultaneously, carries out the A/D conversion by carrying out A/D change-over circuit 31, just can calculate the big or small of AC signal by the CPU on the single-chip microcomputer 3 32 like this and also can show by display device.

Wherein, pressure limiting circuit 4 is exactly protective effect; the sample circuit 1 of front is if problem; when causing the signal of this point of high level output terminals A CA of sample circuit 1 to exceed certain scope; D1 is with conducting; therefore the signal of this point can be clamped down on 0 and arrive in the scope of 3.3v, protect the circuit of back, the security of circuit is higher.

Claims

1, a kind of alternating current, tension measuring circuit that adopts AC sampling, it is characterized in that: this circuit comprises sample circuit, comparator circuit and single-chip microcomputer; Sample circuit is converted to the AC signal output to be checked that tool is determined proportionate relationship with the AC signal in loop to be checked; Comparator circuit is measured the frequency of described AC signal to be checked and this frequency signal is exported to and samples in the single-chip microcomputer; Be provided with the A/D change-over circuit in the single-chip microcomputer, the A/D change-over circuit carries out the A/D conversion to AC signal to be checked and exports the CPU of single-chip microcomputer to, CPU on the single-chip microcomputer is according to the frequency signal of comparator circuit input, and decision is calculated the size of AC signal and exported result of calculation the frequency of AC signal sampling.

2, the alternating current of employing AC sampling according to claim 1, tension measuring circuit, it is characterized in that: described sample circuit is made up of linear transform circuit and voltage reference circuit, linear transform circuit is converted into the ac voltage signal output to be checked that tool is determined proportionate relationship with the ac current signal in loop to be checked, the low level output terminal of linear transform circuit is connected with the reference voltage terminal of voltage reference circuit, so that the negative half-cycle signal of sample circuit output is more than zero point.

3, the alternating current of employing AC sampling according to claim 1 and 2, tension measuring circuit, it is characterized in that: the high level output terminal at sample circuit is connected with pressure limiting circuit, is controlled in certain scope in order to the magnitude of voltage with the high level output terminal of sample circuit.

4, the alternating current of employing AC sampling according to claim 1 and 2, tension measuring circuit is characterized in that: described single-chip microcomputer adopts the MSP430F series monolithic.