Wireless permanent magnet temperature & field distribution measurement system for IPMSMs

Permanent magnet (PM) temperature measurement/estimation in permanent magnet synchronous machines (PMSMs) is of great importance for torque control and to prevent PM demagnetization. PM temperature estimation methods can be divided into thermal models, BEMF and pulse/high-frequency signal injection based methods. All of them provide a lumped PM temperature estimation. However, the temperature distribution along the magnet is not uniform, also asymmetries among poles can exist. Analyzing the impact of the temperature variations on the magnet field distribution requires simultaneous measurement of the PM temperature and field distributions. However, this is not easy due to the large amount of temperature and field sensors required, which places significant challenges regarding the sensors integration as well as the signal acquisition and transmission. Most of temperature measurement systems using contact type sensors that have been reported use a reduced amount of sensors and relatively low sampling rates. Furthermore, they do not include field sensors. This significantly limits the analysis that can be realized. This paper presents a wireless PM temperature and field measurement system for PMSMs. The developed system provides PM temperature and field distribution maps for all the poles with high spatial resolution and bandwidth. Uses of the developed system include analysis of the surface and internal PM temperature distribution, PM field distribution, assessment of local demagnetization risks due to hot spots in PMs, as well as development and assessment of new temperature and field distribution estimation methods for PMSMs.