JPS60244870A - Arithmetic measuring method of alternating current signal - Google Patents

Abstract

PURPOSE:To prolong considerably a data processing time and to perform sufficient processing by a general A/D converter and a general operational element by increasing the number of times of sampling in one period for intermittent sampling. CONSTITUTION:Sample holding circuits 14 and 15, an A/D converter 17, an arithmetic processor 18, a multiplexer 16, and a memory part 19 are provided. Each period of an AC signal input waveform is divided into numbers of a sampling sections, and the sample holding circuits 14 and 15 sample all sections in every period intermittently and successively as many times as possible without the repetition of the same sampling period; and the results are measured by the arithmetic processor 18 as a waveform approximate to an AC input signal whose one period corresponds a number obtained by the number of sampling periods in one period of the input waveform through the sampling circuits, and the arithmetic of sampling data, all-sampling-section arithmetic I of the last approximate waveform, totalization arithmetic II of data, and the output are performed divisionally between sampling periods.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an arithmetic and measurement method for alternating current signals and is intended to measure alternating current signals with a simple configuration and with high precision.

The configuration of a conventional example and its problems The case of measuring the voltage, current, active power, apparent power, etc. of an AC signal will be explained. When the instantaneous values of the voltage and current of the input signal are v', i, and T, respectively, the electrical quantities are defined as follows.

(3) Active power W-(S'i'・1dt)/T...
(3) First, the configuration of the conventional example will be explained with reference to FIG. In the figure, 1 and 2 are current and voltage signal input terminals, 3 is a digital output terminal for measured values, and 4 is a digital output terminal for measured values.
, 5, 6.7 are current/active power/voltage apparent power converters, respectively, which convert the results of the analog calculations of equations (1) to (4) above for each measurement item into DC output and output it. do. 8 is a multiplexer which receives a plurality of inputs I and W according to instructions from the arithmetic processing unit 10;

One of V and V'A is fully selected and output to the A/D converter 9. The arithmetic processing unit 1Q supervises the entire measuring device, and performs switching of the measuring circuit, measurement commands to the A/D converter 2, reading of measurement results, and data output to the output terminal. As described above, since one converter is provided for each measurement item, the device becomes large and expensive when there are many measurement items.

OBJECTS OF THE INVENTION The present invention eliminates these conventional drawbacks and measures alternating current signals with a simple configuration and high accuracy.

Structure of the Invention As a structure for this purpose, the present invention includes a sample and hold circuit, an A/D converter, an arithmetic processing unit, a memory section, and an output section, and divides each period of an AC signal input waveform into a large number of sampling sections. , sample intermittently as many times as possible in each cycle, and sample all intervals in the same way so that they are not the same sampling interval, to obtain a period equal to the number of sampling intervals in one cycle of the input waveform divided by the sampling circuit. is measured as a waveform approximate to the AC input signal with one period, and furthermore, between each sampling, calculation of the sampling data, calculation of the entire sampling period of the previous approximate waveform, data aggregation calculation■, and division of the output are performed. This is how it is done.

Description of examples An embodiment of the present invention will be described below with reference to FIG.

In the figure, 11 and 12 are current and voltage signal input terminals, respectively, and 13 is a measured value output terminal.

Reference numeral 14 and 15 are sample and hold circuits that sample all instantaneous values of the AC signal and hold the values during the next sampling period of sampling 1. 16 is a multiplexer, 17 is an A/D converter, and 18 is an arithmetic processing unit, which has a function of controlling the entire measuring device. 19
is the memory part.

The operation will be explained below with reference to Figure 3.0 First, in Figure 3, (a) is a current input waveform, (b) is a voltage input waveform, and (C) is a sampling command waveform given to the sample and hold circuit from the arithmetic processing unit. , (d) are timing diagrams showing the order of operation of each part in one sampling period.

If each period of voltage and current signal input is divided into TiN sampling periods and sampled X times in one period of the input signal, the sampling period within the same period will be τ/X,
The sampling period for the next cycle is (τ/X+τ/N)
It is.

If we now sample the nth interval, the outputs of the sample and hold circuit will be N in and Vn, respectively, as shown in the figure, and this value will be the next (n + x
) is retained until the second sampling is performed.

The operation of each part within the sampling period is to process the sampling data as shown in (d), first sampling the data, then measuring 1n (A/D conversion), measuring Vn, and performing calculation 1 and 0 calculation. ■ and the output interval are the same as above in the normal sampling cycle, and the calculation and data output are performed at the end of the measurement cycle, that is, in the next N/X cycle interval after the completion of the N/X cycle of the input waveform. conduct.

The contents of operation I are as follows.

(3) W' −1ne vn+, X= 1i, ・v
, (Cumulative sum of products) The content of operation ■ is the following numerical operation.

(1) V = J V'/N (2) I-J'/N (3) W = W'/N (4) V A = V A'/N, as explained above, 1 of the input waveform By performing sampling X times in a period, sampling for all sampling sections is completed in N/X cycles of the input waveform, but sampling may be performed sequentially in the order of the divisions of the sampling section or at any time. .

Note that the calculation process is performed between each sampling hold, but it is not limited to the above calculation formula, and the calculation process is performed between each sampling value vn, 1n, 1n, vnl 1n+ vn
It is also possible to calculate only j, store the result of the calculation in memory, and then calculate after the completion of sampling for all sampling intervals and before operation ■, in short, calculate the sampling results and store the results of all sampling. The total work time, which is the sum of the output work time and sampling time, is set to be 2N/X cycles of the input waveform, and the number of sampling times is increased as much as possible by minimizing calculation down time. , measurement accuracy can be improved by making it possible to perform measurements that are faithful to the input waveform.

That is, according to the method described above, the above (1).

(2), (3), (41 formula 2 approximation) V, I
, W', VA. This method provides a method for realizing highly accurate sampling measurement by increasing the number of divisions N and the number of samplings per period x7. It should be noted that the calculation formula explained above shows one example, and the reactive power and the active power amount.

It is also possible to output multiple electric cables by calculating reactive power amount and power factor. Furthermore, by increasing the number of inputs, it is possible to measure polyphase circuits as well.

Effects of the Invention As detailed above, by using intermittent sampling according to the present invention, the data processing time can be greatly expanded, and it is possible to sufficiently perform the above-mentioned processing even with general-purpose A/D converters and arithmetic elements. This made it possible. Furthermore, the 0(1) method of simultaneous sampling of instantaneous values of multiple inputs, which has the effects described below, enables the calculation output of multiple inputs.Therefore, active power and apparent power can be calculated without the need for a measurement circuit. The active power value and apparent power value can be measured. Similarly, reactive power, active energy, reactive energy,
The power factor can also be measured by calculation without the need for a measurement circuit, making it possible to output multi-element calculations.

(2) Since the arithmetic processing unit is used for measurement, the same arithmetic processing unit and memory section can be shared even when displaying and recording sound, making it possible to simplify the overall configuration of the device.

(3) It provides a method that can be made smaller and lighter due to a simple circuit configuration, and has excellent economical effects.

[Brief explanation of drawings]

Figure 1 is a block diagram of the equipment used in the conventional measurement method.
FIG. 2 is a block diagram of an embodiment of the apparatus used in the measurement method of the present invention, and FIG. 3 is a signal waveform diagram of each part. 11... Current signal input terminal, 12...
Voltage signal input terminal, 13...output terminal, 14.
15...Sample hold circuit, 16...
...Multiplexer, 17...A/D converter, 18... Arithmetic processing unit, 19...
memory section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Eka

Claims (1)

[Claims] sample hold circuit, A/D converter, arithmetic processing unit,
It has a memory section and an output section, and divides each period of the AC signal input waveform into a large number of sampling sections, and samples as much as possible in each period intermittently, so that the sampling sections are not the same one after another. The entire interval is sampled and measured as a waveform that approximates the AC input signal, where one cycle is the number of sampling intervals in one cycle of the input waveform divided by the number of sampling times, and further sampling is performed between each sampling. A method for calculating and measuring an AC signal, which comprises performing data calculations, calculations for all sampling intervals of the previous approximate waveform (I), data aggregation calculations (2), and dividing the output.