Total harmonic distortion mitigation in matrix converter ups using fuzzy-logic based active power filter/ Leah Joyce M. Bagaoisan, Danniel Jhay S. Larida, John Clemence Magtulis, Joshua Reyes, Andrea Crisanta G. Sang-olan, and Grace Ann O. Señagan.--

Bachelor's thesis

College Of Engineering.-- Bachelor of science in electrical engineering: Technological University of the Philippines,
2025.

Includes bibliographic references and index.

Low waveform distortion and sustained power delivery under dynamic load
conditions are two things that traditional UPS systems frequently fall short of. To fill these
gaps, this study assesses an Uninterruptible Power Supply (UPS) based on a Single-Phase
Matrix Converter combined with a Fuzzy Logic-Controlled Active Power Filter (FL-APF).
Tests of battery duration under 20%, 60%, and 80% load conditions showed that runtime
and load demand were inversely correlated. The system maintained a steady voltage output
of 228.30V and minimal battery discharge (12.61V to 12.12V) for 2 hours and 47 minutes
while operating at a 20% load (54W). The system's runtime decreased to 1 hour and 12
minutes at 60% (181.6W) and only 29 minutes at 80% (231.3W). The UPS continuously
maintained output voltages close to the nominal 230V and recovered efficiently after
operation, even though heavier loads increased inverter stress. Additionally, an analysis of
Total Harmonic Distortion (THD) at various load levels revealed increasing distortion:
2.2361% at no load, 2.3259% at 20%, 2.7731% at 60%, and 3.1305% at 80%. The efficacy
of the fuzzy-logic-based APF was demonstrated by the fact that THD stayed within the
target threshold of ≤3% even during peak conditions. Significant improvements in
waveform purity when connected via UPS were confirmed by additional device-specific
THD evaluations. When non-linear loads were tested, the THD of an HP laptop decreased
from 8.36% when connected directly to the grid to 3.17% when using a UPS; the THD of
a Dell laptop decreased from 12.03% to 3.42%; and the THD of an audio amplifier
decreased from 10.60% to 3.12%. These improvements validate the system’s real-time
harmonic suppression capability and its suitability for powering sensitive electronics.