K. Ahmadi

1. Adaptive gradient descent–based maximum power point tracking algorithm for low-power photovoltaic systems with complexity-aware performance analysis
   Kimia Ahmadi; Wouter A. Serdijn;
   Nature Scientific Reports,
   25 August 2026. DOI: 10.1038/s41598-026-66286-7
   
   Keywords: ...

   Maximum power point tracking (MPPT), Photovoltaic energy harvesting, Adaptive perturb-and-observe (P&O) algorithm, Partial shading conditions (PSC), Computational complexity benchmarking.
   
   
   Abstract: ...

   Maximum power point tracking (MPPT) in low-power photovoltaic (PV) and optical wireless power transfer (OWPT) systems must simultaneously provide high tracking efficiency, fast response, and low implementation cost. However, conventional perturbative methods often suffer from slow convergence or steady-state oscillations under rapid irradiance changes, whereas intelligent and metaheuristic approaches can improve tracking but typically increase computational complexity, memory demand, and hardware cost, limiting their suitability for compact embedded energy-harvesting systems. Here, we propose an adaptive gradient-descent-based perturb-and-observe MPPT algorithm for resource-constrained implementation. The method uses the analytical power–voltage gradient to adapt the duty-cycle perturbation direction and step size, enabling fast transient tracking, while a threshold-based suppression mechanism reduces steady-state perturbations near the maximum power point. A lightweight optional initialization routine based on a coarse duty-cycle sweep improves global tracking under partial shading with limited memory and computational overhead. We also introduce a normalized ASIC-oriented computational-complexity analysis for operation-level comparison of conventional, intelligent, and hybrid MPPT algorithms. Evaluated in a fixed-point MATLAB/Simulink framework with two 10-bit ADCs, an 8-bit duty-cycle command, a DC–DC boost converter, and a 1 MHz PWM stage, the proposed algorithm achieves 99.94% MPPT efficiency under standard test conditions, 99.21% under experimentally derived motion-induced irradiance, and up to 7.8 percentage-point improvement under severe partial shading.
   
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2. Advancements in Laser and LED-Based Optical Wireless Power Transfer for IoT Applications: A Comprehensive Review
   Kimia Ahmadi; Wouter Serdijn;
   IEEE Internet of Things Journal,
   pp. 1-25, 2025. DOI: 10.1109/jiot.2025.3542968
   
   Abstract: ...

   Optical wireless power transfer (OWPT) has emerged as a promising technology for efficient wireless power transfer (WPT), offering advantages such as directionality, suitability for far-field applications, and the ability to transfer power and data simultaneously. This comprehensive review classifies OWPT systems into laser power transfer (LPT) and LED-based OWPT. LPT uses the narrow divergence of laser beams for high-density, long-distance energy transfer, making it suitable for applications such as satellites, autonomous drones, and electric vehicle charging. In contrast, LED-based OWPT offers a safer, more cost-effective solution for low-power applications, especially in the Internet of Things (IoT) domain. It offers advantages such as lower power consumption and fewer safety restrictions compared to LPT. Innovations in LPT, such as high-intensity laser power beaming, distributed laser charging, adaptive distributed laser charging, simultaneous lightwave information and power transfer, and resonant beam charging are discussed. Also, recent advancements in LED-OWPT, including single-lens and double-lens systems, collimation techniques, and multi-LED arrays, are explored for their potential in powering IoT devices, wearable electronics, and smart infrastructure. First, we present a radar chart comparing various WPT techniques with respect to performance criteria. After reviewing the methods of LPT and LED-OWPT in detail, a comparison of these techniques is provided, evaluating their strengths, limitations, and application suitability. A concluding radar chart offers insights for optimizing OWPT systems tailored to specific applications. Future research directions are identified, emphasizing the need for further advancements in beam alignment, safety protocols, and hybrid systems to enhance OWPT’s scalability and practicality in real-world scenarios.
   
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