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Fuzzy logic and active power line conditioners (APLC) are two tools that are being increasingly applied to power quality problems. In this paper, a switch-mode APLC that uses fuzzy logic to control the semiconductor switches is described. Frequency-domain analysis is used to determine the desired compensation current, and a rule-based piecewise-linear fuzzy proportional-integral controller (FPIC) provides the appropriate switching pattern of the APLC to generate the actual compensation current. MATLAB simulations and experimental measurements on a low-power (700 VA), digital signal processor-based, hardware prototype show that the APLC produces excellent results despite the use of a relatively low switching frequency, which is necessary to minimize semiconductor switching losses. The simulations and measurements are in good agreement and show that the APLC/FPIC system can significantly improve line current total harmonic distortion and power factor during both steady-state and transient operating conditions.
Date of Publication: Nov. 2004