| 摘要 |
An adaptive harmonic filter is provided to reduce manufacturing cost by minimizing erroneous operation in comparison with a micro-controller by using only an analog device. An adaptive harmonic filter includes a plurality of passive filters(32a,32b,32c,32d), a plurality of filter driving units(38a,38b,38c,38d), a current detecting unit, and a plurality of harmonic detecting units. The plurality of passive filters are connected between a power(30) and a non-linear load(40) which generates harmonics, and filters the harmonics. The plurality of filter driving units connect or cut off the plurality of passive filters to or from the power. The current detecting unit is connected between the power and the non-linear load, and detects current. The plurality of harmonic detecting units detect (2n+1)th harmonics from the current detected through the current detecting unit, compares the detected intensity of harmonics with a preset reference value, and filters the harmonics by the passive filter in case that the corresponding harmonics need to be filtered. The harmonic detecting unit consists of a reference setting device which detects a basic frequency of the power and sets the reference value, tertiary/quinary/septenary/nonary harmonic detecting devices which detect the intensity of tertiary/quinary/septenary/nonary harmonics from the power, and tertiary/quinary/septenary/nonary comparing units(63a,63b,63c,63d) which compare the intensity of harmonics detected by the tertiary/quinary/septenary/nonary harmonic detecting devices.
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