Master Thesis: Embedded Real-time Identification of Coupling Factor for Inductive Energy Transfer Systems

This repository contains all the necessary files for the Master's Thesis completed at the Institute of Electrical Energy Conversion (IEW), University of Stuttgart. The project focuses on the development and implementation of a parameter estimation method for Wireless Power Transfer (WPT) systems.

The system identifies the coupling factor ($k$) in near real-time by processing the system's transient response on an STM32 microcontroller.

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🚀 Key Features

• Real-time Estimation: Measures the coupling factor $k$ in less than 5 ms using a 4096-point FFT.
• Multiple Topologies: The method is validated for both Series-Series (SS) and LCC-LCC compensated WPT systems.
• Embedded System: Fully implemented on an STM32 microcontroller.
• Comprehensive Simulations: Includes detailed simulation models in MATLAB, Simulink, and PLECS.

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📂 Repository Structure

.
├── 1_Codes/
│   ├── STM32/              # STM32 source code (C/C++)
│   └── MATLAB/             # MATLAB, Simulink, PLECS simulations & analysis scripts
├── 2_Presentation/
│   └── abschlussraesentation_sarath.pptx
├── 3_Thesis_Document/
│   └── Master_Thesis_Sarath_final_version.pdf
├── LICENSE
└── README.md

🔬 Methodology

The estimation technique is based on the effect of impulse response observed in coupled resonant circuits.

1. A short voltage impulse (5µs) is injected into the secondary side of the WPT system.
2. The resulting transient current on the primary side is sampled by the STM32's ADC.
3. A 4096-point Fast Fourier Transform (FFT) is performed on the sampled data to move to the frequency domain. Different sizes are also compared to see their effect on the system.
4. The resulting spectrum shows a set of distinct resonant peaks. The number of peaks depends on the compensation topology:
   • Series-Series (SS): 2 distinct peaks.
   • LCC-LCC: 4 distinct peaks.
5. The frequencies of these peaks are directly related to the system's coupling factor, $k$. The exact relations are derived and explained in the thesis document for each topology.

The method was verified against both simulation results and a physical test bench.

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🛠️ Getting Started

Prerequisites

• Hardware:
  • STM32 Nucleo Board (or similar)
  • Custom WPT hardware (SS and LCC-LCC topologies)
  • Current probe and oscilloscope for verification
• Software:
  • STM32CubeIDE
  • MATLAB & Simulink with PLECS Blockset

Installation and Usage

1. Clone the repository:

   https://github.com/maimpilly/Master-Thesis.git

2. Run Simulations: Open the matlab files in the 1_Codes/MATLAB/ directory with MATLAB to run the system simulations. The file initialise_model.m script can initialise the model along with all the parameters and run the simulation for a single time.
3. Deploy Firmware:
   • Launch STM32CubeIDE and import the project from the 1_Codes/STM32/ directory.
   • Build the project and flash it to your STM32 board.
   • Connect to the board via MATLAB and run the corresponding script to view the real-time coupling factor estimations.

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📜 Citation

If you use this work for research, please cite the thesis.

@mastersthesis{Maimpilly2025,
  author  = {Sarath Chandran Maimpilly},
  title   = {Embedded Real-time Identification of Coupled Factor for Inductive Energy Transfer Systems},
  school  = {University of Stuttgart},
  year    = {2025},
  address = {Stuttgart, Germany}
}

⚖️ License

This repository is dual-licensed.

• All source code in the 1_Codes/ directory is licensed under the MIT License. See the LICENSE file for details.
• The thesis document and presentation in the 2_Presentation/ and 3_Thesis_Document/ directories are licensed under the Creative Commons Attribution 4.0 International License.