Abstract

The Positive Output Luo Converter (POLC) has been widely applied in DC–DC power conversion due to its combined buck–boost capability and non-inverting output voltage. The converter topology has included multiple energy storage elements, which has increased the system order and has resulted in nonlinear dynamic behavior. These characteristics have made the closed-loop voltage regulation of the POLC challenging under source and load disturbances. Conventional proportional–integral (PI) control has remained attractive due to its simplicity, but the fixed gain selection has limited its performance in higher-order nonlinear converters. Classical tuning methods have provided acceptable initial responses; however, they have failed to ensure optimal transient and steady-state performance under varying operating conditions. In this work, a PI-controlled POLC has been analyzed initially using the Ziegler–Nichols tuning method, which has supplied baseline gain values. These gains have been further refined using three nature-inspired optimization techniques: particle swarm optimization, cuckoo search algorithm, and crow search algorithm. Each algorithm has independently estimated optimal proportional and integral gains that have minimized performance indices related to overshoot, settling time, and steady-state error. In addition, an internal model controller (IMC) has been designed using forward and inverse transfer functions that have been identified through MATLAB Simulink using the iddata and tfest tools, which have enabled accurate system modeling. Simulation studies have demonstrated that optimized PI controllers have achieved superior voltage regulation compared to conventionally tuned controllers. Among all control strategies, the IMC has delivered the most consistent tracking performance and disturbance rejection. The control effort that has been required by fuzzy logic, artificial neural network, and adaptive neuro-fuzzy controllers has also been evaluated, and the IMC has exhibited reduced control action with improved robustness. These results have confirmed that model-based control has outperformed heuristic and classical approaches for POLC regulation.

Authors

S.V. Kayalvizhi¹, V. Suresh²
St. Xaviers Catholic College of Engineering, India¹, Mar Ephraem College of Engineering and Technology, India²

Keywords

Positive Output Luo Converter, PI Controller Optimization, Internal Model Control, Nature-Inspired Algorithms, DC–DC Converters