Sensorless Vector Control for Induction Motor Startup Using Multilevel Converters

Multilevel converters are increasingly viewed as the next generation of motor drives, offering advantages such as reduced harmonics, enhanced electromagnetic interference (EMI) performance, and greater flexibility and scalability in voltage and current levels. Despite these benefits, a significant challenge arises during the startup of induction motors driven by multilevel converters, primarily due to AC voltage fluctuations in the DC capacitors of each submodule. Additionally, the use of voltage sensors, while commonly, introduces potential points of failure and increases overall system costs. To address these issues, this paper presents a novel sensorless vector control strategy based on speed and phase angle estimation. The proposed method has been empirically verified to achieve successful startup with accurate speed estimation and minimal AC voltage fluctuation.