Abstract
This paper proposes an enhanced fuzzy logic controller (FLC) for photovoltaic (PV) systems, featuring a novel reduced-order design. It introduces a significantly simplified FLC for MPPT in a 10-kW grid-connected PV system. The proposed controller minimizes both the number of input variables and the number of membership functions (MFs). Specifically, it utilizes only a single input, the sum of conductance and its increment, and employs just five rules, a substantial reduction compared to the 25-49 rules typical in standard FLCs. Integrated within a system architecture featuring a DC-to-DC converter and a 3-level voltage source converter (VSC) for grid power transfer via duty cycle control, this highly reduced FLC maintains robust MPPT performance through adaptive responses to varying weather conditions. Consequently, it achieves considerable simplification in implementation complexity without sacrificing operational efficiency. To our knowledge, this FLC is among the few controllers capable of such significant rule reduction while maintaining performance. Key results show that at 1 kW/m², incremental conductance (IC) achieves 99% efficiency compared to FLC’s 96%. Under medium irradiance (0.5 kW/m²), FLC outperforms IC by 5% (93% vs. 88%). For low irradiance (0.2 kW/m²), both reach 95.2%. Under large irradiance steps (0.4 to 1 kW/m²), the FLC achieves 22× faster convergence than IC (0.015 s vs. 0.33 s), demonstrating superior dynamic response to abrupt solar variations. This highlights the proposed algorithm’s robustness for dynamic weather scenarios while maintaining competitiveness in steady operation.

Key words: MPPT, Power Grid, Fuzzy Logic Controller, FLC