Researcher in the Spotlight: Lie Wang

Linear reluctance motor with advanced power electronics converter

"Hello, my name is Lie Wang. My PhD research is entitled the ‘Development of new generation linear reluctance drives: Linear reluctance motor with Advanced Power Electronics Converter’."

"An integrated electric drive demands low-volume, lightweight power converters; Multi-level topologies with improved output quality and fewer or no filter components are promising. In addition, the converter lifetime is dominated by the thermal cycles of the power semiconductor switches, which are largely influenced by temperature swings and the ambience. Therefore, a modified multi-level converter topology, including the necessary control effort, should be designed to increase the power density as well as the converter lifetime by reducing the temperature swings of each power switch."

Focus on the exploration of operating principles 

"My approach in this research is to focus on the exploration of the operating principles, design and evaluation of different power converter topologies to achieve high-power density and improved lifetime of electric drives for linear actuator applications. I am reviewing different multi-level topologies by evaluating the power losses and efficiency based on measured single-switch data. Furthermore, I am investigating a modified multi-level converter that provides freedom to control the switch temperature by injecting extra circulation current."

Suitable for long-stroke applications 

"Designing a high-power density converter with light weight and low volume could facilitate the integration of a linear actuator mover and converter unit. A moving power converter concept mitigates the voltage stress on the actuator windings caused by a long cable, and the cable slab is simplified as it only connects to the DC supply and no signal wires are included. This make the concept suitable for long-stroke applications, such as smart warehouse automation, conveyor belt or milling machines. Furthermore, with an improved lifetime, the system requires less maintenance and could save on operating costs considerably."

"Interestingly, the power electronic converter has been conceived for application to a linear actuator that is the focus of a study by another PhD student, in which the ultimate goal is to achieve a high-power density and high-force density actuator system. On one hand, the power converter topology and its rating depend on the actuator parameters, while, on the other hand, an improved output quality from the power converter will boost the actuation performance."