Advanced rare earth-free motor drives for energy-efficient pumps in urban applications

The growing emphasis on environmental sustainability has elevated the importance of energy-efficient technologies, particularly in electric motors, which account for over half of global electricity consumption. The adoption of high-efficiency standards for electric motors, along with innovations in control strategies and hardware design, is crucial for reducing energy consumption and mitigating environmental impact. Although induction motors dominate the electric motor market because of their robustness and cost-effectiveness, there is a growing interest in synchronous reluctance motors (SynRMs) and other high-efficiency alternatives that avoid the use of rare-earth materials, which pose both geopolitical and environmental challenges. This research focuses on the development of capacitorless drives and sensorless control techniques for SynRMs, particularly in applications such as pumps, where cost, efficiency, and reliability are essential. The study explores the design and implementation of advanced control methods, eliminating bulky electrolytic capacitors and position sensors to enhance drive durability, reduce costs, and improve remote operability without requiring additional hardware. By collaborating with industry partners, this project develops practical solutions for adjustable-speed drives in pump systems. For several decades, Kalman filter (KF)-based sensorless control techniques have been studied due to their numerous advantages. However, their application in real-world products has been limited by the cumbersome manual tuning required. Key advancements in this PhD project include the use of Adaptive Kalman Filters (AKFs), which feature much easier and nearly automatic tuning procedures. The nonlinear model of SynRMs necessitated the use of nonlinear KF algorithms. Among the various alternatives, determining the most suitable option for synchronous motor drive applications was crucial. To this end, the research initially focused on evaluating different algorithms, particularly comparing the extended Kalman filter (EKF) and unscented Kalman filter (UKF) approaches, assessing their performance in sensorless SynRM control. Throughout the project, the selection of the best algorithm and its straightforward tuning were considered pivotal in promoting the use of KF-based sensorless SynRM drives in pump applications. The findings contribute to the development of reliable, sustainable, and cost-effective electric drive solutions, positioning SynRMs as a key component in the transition to environmentally responsible HVAC and pump systems.