High-Speed Remote Power Measurement by Communication of the Maximum and Minimum Measurement Value

A typical digital power measurement device samples voltage and current several times for one period of voltage and current to determine the root mean square. It is the typical way that the phase begins counting at the voltage zero point and the corresponding power is determined by the value of the counter at the current zero point. The digital power measurement in the above structure reduces sensing precision because, as the frequency of the subjects increases, the number of measurement decreases in one period. In particular, if the frequency to be measured is similar to the sampling frequency, it is practically impossible to measure the power. Therefore, in this paper, I propose a new power measurement system that can detect the maximum and minimum values of instantaneous power and then measure the power using the values. In the proposed method, the relationship between the maximum and minimum values of instantaneous power, apparent power and effective power is investigated and the apparent power and the effective power are identified using the instantaneous power maximum and minimum difference and sum. In the proposed power measurement technique, the measured power–frequency limit is independent of the sampling frequency of the digital part, and is determined by the performance of the analog multiplier and the maximum minimum detection circuit. It is advantageous that the proposed method can measure the accurate power irrespective of the frequency of the subjects to be measured. The validity of the proposed method is demonstrated by simulation and experiment.