CN1607392A - Voltage virtual value measuring method based on filter - Google Patents

Abstract

A method for testing effective voltage value by a filter includes signal sample conditioning, a mean-square-root operation unit and an error corrector, among which, the signal sample conditioning contains a modulator, a LPF1 and a digital HPF, the mean-square-root operation unit is composed of a MUL1, a LPF2 and a SQRT, the error corrector coefficient register. The signal sample conditioning finishes signal sampling accurately, the mean-square-root operation unit finishes computation of voltage effective value according to the data input by sample conditioning and the error corrector corrects the error of the voltage effective value.

Description

Measuring method based on the voltage effective value of wave filter

Affiliated technical field

The present invention relates to a kind of measuring method of utilizing wave filter to carry out voltage effective value.

Background technology

The measuring method of traditional voltage effective value based on sampling theory is the sampled point in the some cycles to be carried out the root mean square computing try to achieve, and according to Circuit theory, voltage effective value is defined as $U_{\mathrm{rms}}=\sqrt{\frac{1}{T}{{\∫}_0^{T}u}^2\left(t\right)\mathrm{dt}},$ With the measurement of sampling computing method realization voltage effective value, its theoretical foundation is sampling thheorem, is satisfying under the prerequisite of sampling thheorem, and measured signal voltage u (t) is carried out N sampling, and its discrete sampling value is U (n), and then voltage effective value can be used formula $U_{\mathrm{rms}}=\sqrt{\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{U}^2\left(n\right)}$ Try to achieve.The weakness of this measuring method maximum is that real-time is poor, precision is not high enough, error jumping table big and degree of stability is poor.

Summary of the invention

The invention provides a kind of measuring method of the voltage effective value based on wave filter.

As shown in Figure 1, the present invention comprises signal sampling conditioning, root mean square arithmetic device and error correction device.The signal sampling conditioning comprises modulator (Mod), low-pass filter (LPF1) and digital high-pass filter (HPF); Root mean square arithmetic device is made up of multiplier (MUL1), low-pass filter (LPF2) and square root extractor (SQRT); The error correction device comprises a multiplier (MUL2), a totalizer (ADD) and a correction factor register (CO).

Signal sampling is finished in the signal sampling conditioning, and realizes the accuracy of signal sampling.By modulator (Mod) analog input signal is modulated into the high-speed data-flow of a bit, finishes analog to digital conversion analog input signal.Certainly, the input signal of this framework also can be the multidigit metadata streams in other sources.Low-pass filter (LPF1) is done down conversion process to a bit high-speed data-flow of modulator (Mod) input, converts multidigit unit low rate data streams to, and frequency reducing resists repeatedly mixed simultaneously.Hi-pass filter (HPF) mainly is to remove the direct current biasing composition that analog device brings in the modulator, guarantees the final accuracy of measuring.

Root mean square arithmetic device is finished the calculating of voltage effective value according to the data of signal sampling conditioning input.Multiplier (MUL1) carries out from multiplication the data of input, also is square operation.Low-pass filter (LPF2) is an averaging filter, realizes all square computing to the output data of multiplier (MUL1).Square root extractor (SQRT) is finished the extracting operation to the output data of low-pass filter (LPF2), tries to achieve root mean square, also is effective value.

The error correction device is revised the error of calculating the voltage effective value existence of trying to achieve through root mean square arithmetic device, guarantee the degree of accuracy of voltage effective value, correction formula is that (wherein Out2 is an output valve to Out2=In2+Co*In2, In2 is the voltage effective value that calculating is tried to achieve through root mean square arithmetic device of input, and Co is a correction factor.), the output of error correction device promptly is final voltage effective value like this.

Adopt the present invention that following advantage is arranged:

1, higher degree of accuracy

Adopt modulator to analog signal sampling, obtain a bit data stream at a high speed, all kinds of wave filters are reduced to minimum zone with all kinds of noise effects, make The ultimate results have higher degree of accuracy.

2, higher stable degree

Adopt filter construction, guarantee that the effective value of the sinusoidal signal measured has advantages of higher stability in certain frequency band.

3, simple in structure

Calculating voltage effective value of the present invention need not to carry out period measurement accurately, only needs to adopt method synchronous or accurate synchronized sampling to realize, has simplified the miscellaneous work that the conventional voltage effective value is measured, and very easily realizes in digital circuit and software.

The present invention can be applicable to TT﹠C system, and aspects such as instrument and meter comprise the measurement of signals such as the light that can convert electric signal to, sound, flow, gas.

Description of drawings

Fig. 1 is the structured flowchart of measuring voltage effective value of the present invention.

Embodiment

In the multifunctional electric energy meter to the measurement of voltage effective value, adopt the sigma-delta modulator that sampling voltage is sampled, obtain a bit data stream near 1MHz, through adopting the low-pass filter of pectination (Comb Filter) structure, bit high-speed data-flow to modulator output is done down conversion process, convert low speed multidigit metadata streams to, resist in the time of frequency reducing and mix repeatedly filtering, owing to only consider pure AC signal, utilize a digital high-pass filter that the low rate data streams after the frequency reducing is carried out every straight processing.Through promptly obtaining voltage effective value after the root mean square arithmetic device of forming by multiplier, digital filter and square root extractor, adopt the error correction device that the error of the voltage effective value that obtains is revised through the data after straight at last.

Claims (4)

1, a kind of measuring method of voltage effective value is characterized in that analog input signal is modulated, and utilizes wave filter to carry out the root mean square computing and the root mean square operation result is carried out error correction.

2,, it is characterized in that the signal sampling conditioning structure that adopts modulator, low-pass filter and digital high-pass filter to form according to right 1 described method;

3,, it is characterized in that the root mean square arithmetic device that adopts multiplier, wave digital lowpass filter and square root extractor to form according to right 1 described method.

4,, it is characterized in that the error correction device that adopts multiplier, totalizer and correction factor register to form according to right 1 described method.