Preliminary Study of the Finite-Set Model Predictive Control for Five-Level Vienna Rectifier

Tan, Bryan Xiao Yung (2024) Preliminary Study of the Finite-Set Model Predictive Control for Five-Level Vienna Rectifier. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

This project delves into the transformative landscape of renewable energy, with a specific focus on Wind Energy Conversion Systems (WECS) and the intricate control dynamics within a fivelevel Vienna rectifier for medium to high power application. This study introduces an model predictive direct torque control integrated with look-up table-based voltage balancing for a permanent magnet synchronous generator (PMSG) employing a five level Vienna rectifier within a wind energy conversion system. A stator voltage model was developed to deeply analyse how the switching vectors of the five level Vienna rectifier impact the direct torque control's performance. The PMSG model was tailored to a novel labelling system for five level rectifier space vector, leading to a new PMSG model with ‘r’ and ‘k’ parameter for torque and flux computation. Additionally, voltage balancing look-up table was design using the stator voltage model developed to improve system balance. The methodology was initially evaluated using MATLAB/Simulink. Comparative analysis against existing direct torque control approaches verified the feasibility of model prediction direct torque control for five level Vienna rectifier of the proposed PMSG in wind energy conservation systems. The simulation results demonstrated that the developed control system utilizes Model Predictive Direct Torque Control (MPDTC) tailored specifically for the 5L-VR, allowing precise control of the reference speed at 6000 and 8000 RPM. Simulation results demonstrate effective reduction in Total Harmonic Distortion (THD) in the stator current waveform, with THD values decreasing from 20.23% at 6000 RPM to 16.63% at 8000 RPM. This improvement indicates enhanced waveform quality and stability at higher speeds. Precise torque control was achieved with fluctuations within acceptable limits, highlighting the effectiveness of MPDTC tailored for the 5L-VR configuration. Additionally, the implementation of a voltage balancing Look-Up Table (LUT) effectively controlled Vdc/2 within a tight range, ensuring stability and uniformity in voltage distribution. Furthermore, the system exhibited robustness during transient speed changes and unbalanced load conditions, maintaining performance and mitigating THD. These findings validate the proposed MPDTC strategy's suitability for high-speed applications and its ability to enhance PMSG performance in wind energy systems, offering practical insights for real-world implementations.