Events at Department of Energy Technology

PhD defence by Simon Staal Nielsen


18.08.2021 kl. 13.00 - 16.00


Simon Staal Nielsen, Department of Energy Technology, will defend the thesis "Compact, Efficient and Flexible Drive Unit with Wide Operating Area for Conveyors"


Compact, Efficient and Flexible Drive Unit with Wide Operating Area for Conveyors


Simon Staal Nielsen


Associate Professor Peter Omand Rasmussen


Associate Professor Kaiyuan Lu


Associate Professor, Lasse Schmidt, Aalborg University (Chairman)
Professor Hamid A. Toliyat, Texas A&M University
Professor Yujing Liu, Chalmers University of Technology


This dissertation investigate a suitable application for magnetic gearing technology through the specific case of a drive unit for conveyor applications. The conveyor drive unit is designed as a system consisting of a magnetic gear, a permanent magnet machine and an inverter. 
The thought of utilising magnetic fields for gearing to obtain benefits of contactless power transfer has been a motivation for scientists since the beginning of the 20th century. The invention of the high energy product rare earth magnets has been an enabler for magnetic gears with high torque density, and during the latest two decades, the research within the field have picked up pace. Many demonstrators have been build, mostly evolving around the concentric magnetic gear (CMG) type which offers high torque density with a "relatively" simple mechanical construction. Direct comparisons between magnetically geared electric machines and direct drive machines have shown very positive results regarding torque density, energy efficiency and material consumption. 
Magnetic gearing technology have not had a commercial breakthrough despite the many demonstrators which have shown an increasing understanding of the technology. However, except a few specialised cases, the trend in the most resent work describing magnetic gears in specific application converges toward low speed, high torque applications, where the magnetic frequency, and hence rotational losses, can be kept sufficiently low. These characteristics are found in the conveyor industry, and because conveyors are used extensively within many different industries, this case pose a great opportunity for a commercial breakthrough where characteristics such as high energy efficiency, inherent overload protection, contactless power transfer and no need for lubrication will make a difference. 
Through this dissertation, three iterations of a demonstrator for a magnetically geared conveyor drive unit are presented. A complete drive unit is a complex system, hence each demonstrator is used to narrow down the special focus points for modelling work and development for the next version. The last demonstrator, MagCon V3, represents a drive unit with a peak system energy efficiency (grid to chain) of 78.5% in the relevant operating area for a sprocket output power of 431 W, and the torque density for the CMG reaches 133 Nm/l. 
A novel, commercially feasible approach to manufacture the ever challenging segment ring for the CMG is presented, where flanges are moulded directly onto the laminations stack via injection moulding. 
Thermal steady state tests show great results at low to medium speed. At high speed, thermal challenges are encountered despite a low maximum temperatures of 84 degree C in the gear and 97 degree C in the motor windings. It is believed that the problem is caused by a mismatch between thermal expansion for laminations and polymer in the segment ring, and an alternative polymer is presented with a coefficient of thermal expansion similar to that of steel laminations. 
Acoustic noise at a level higher than expected is experienced, however, this is shown to be caused by an inappropriate pole- and segment combination in the CMG, and by changing this, the acoustic noise level will likely be decreased substantially. 
Two main challenges with acoustic noise and thermal expansion are likely solved by material choice and an improved pole/segment combination, and it is believed that the conveyor application will be a very good application for the CMG.


THE DEFENCE will be IN ENGLISH - all are welcome.

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Department of Energy Technology


Pon 111, 1.077