| 摘要 |
PURPOSE:To achieve a counter time limit characteristic having small error over a wide frequency band by employing a function represented by Z conversion for digital filter processing then calculating the amplitudes of current and voltage based on the digitally processed data and judging the operation based on an operation judging formula represented by an integration formula. CONSTITUTION:The sampling period is set to 1/4n of commercial period (where, n is a natural number) then input current and voltage (v) are fed to a digital filter for performing Z conversion of 1/2(1-Z<-2n>). The square values of the amplitudes of output current Im=1/2(im-im-2n) and output voltage Vm=1/2(vm-vm-2n) (where, m is a sampling time series) are operated through amplitude squaring method I<2>=I -ImIm-2n, V<2>=V -VmVm-2n, thus judging the necessity of operation based on an operation judging formula shown by the integration formula II. Consequently, a counter time limit characteristic having square approximation characteristic can be achieved over a wide frequency band through combination of a frequency characteristic based on digital processing and a frequency characteristic based on amplitude squaring operation. |
