True virtual value measurement method and circuit for random waveform

Abstract

The invention discloses a true virtual value measurement method and circuit for a random waveform. The process is that: an instantaneous voltage signal of the random waveform is acquired, and the instantaneous voltage signal is subjected to attenuation and filtering processing; the processed signal is subjected to sampling and calculation processing to obtain a virtual value, and the virtual valueis converted into a direct-current voltage signal; the direct-current voltage signal is changed into a corresponding digital signal by analog-to-digital conversion; and the digital signal is converted according to an attenuation coefficient to obtain the actual virtual value. According to the invention, the virtual value of the waveform is obtained according to mathematical definition of the virtual value by acquiring an instantaneous value of the voltage of the to-be-measured waveform, taking an average value after carrying out square processing and then calculating a square root of the average value. Such measurement method completely accords to the definition of the virtual value and has no requirements for the shape of the waveform; and the measurement method is simple, effective andhigh in universality.

Description

technical field [0001] The invention belongs to the technical field of effective value measurement, and in particular relates to a method and circuit for measuring the true effective value of an arbitrary waveform. Background technique [0002] For alternating current, its voltage is a changing waveform. Usually we describe its voltage value as its effective value, such as what we call 220V power supply, its peak voltage is 311.2V, and its peak value is 622.4V. [0003] The effective value is defined by heat generation (power): the heat generated by a certain AC passing through a resistor is equal to the heat generated by another DC passing through the resistor in the same time, then the DC voltage value is the effective value of this AC voltage value. Its mathematical definition is: where V rms is the effective value, T is the measurement duration, and V(t) is the instantaneous voltage, which is a function of time but not necessarily periodic. [0004] In general measu...

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Problems solved by technology

[0004] In general measuring instruments, it is difficult to measure the effective value by heating, so in most voltage measuring instruments, the measurement method is not measured according to the "heat" defined by the effective value

The existing class of multimeters generally take the sine wave as a reference, and obtain the effective value (or deduce it by the average value) through the relationship between the effective value whose peak value is twice the square root of the sine wave. Using this method to obtain the effective value only Suitable for AC voltages with sinusoidal waveforms, not for other shapes of waveforms

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