CONTROL DEVICE OPTIMIZING COMPUTING INPUT SAMPLE OF DATA WITH DISCRETE FOURIER TRANSFORM ALGORITHM

摘要

An automatic control device (1) that comprises input means (21, 24) for inputting measured values (7) of cyclic voltage and/or current; computing means (21) for computing a parameter based on said values of voltage and/or current, and for comparing the computed parameter against a predefined condition; and initiating means (21, 23) for initiating a control function in response to the parameter meeting the predefined condition. The input means (21, 24) of the control device are arranged to input a predefined number of samples per one cycle; and said computing means (21) are arranged to compute the parameter with a discrete Fourier transform algorithm optimized based on fixed coefficients related to said predefined number of samples per cycle. The control device and the corresponding control method provide a significantly faster response time than the earlier general programmed solutions without increasing the related costs as much as the conventional digital signal processors.