I want to monitor the temperature rise in the magnet which is surface mounted in permanent magnet motor, while the motor is running at rated current. How can you practically realize it with the help of thermocouple or RTD?
Dear Sree Ranjini Kizhakkethil,
With a non-modified PMSM, I would say it is impossible to directly measure the rotor temperature with a thermocouple while running the machine. The reasons being the cable of the thermocouple that will roll around the rotor, the lack of space in the air gap, etc.
Though, there are indirect measurements that have proved to be of good quality. One of the most used method is a flux observer utilizing the fact that the permanent magnet flux is temperature-dependent. By measuring the flux and knowing the behavior of your magnet, it is possible to indirectly measure its temperature.
Exemple publication of an observer (other exists):
Conference Paper Observer for the rotor temperature of IPMSM
Otherwise, I recommand you to find this article:
https://www.tandfonline.com/doi/abs/10.1080/09398368.2016.1209877?src=recsys&journalCode=tepe20
Some try with wireless techniques also, which, depending on the speed and size of your motor can be practical (the wireless module has to be on the rotor and thus must stick to it while not providing too much influence on the rotor).
Finally, if all of that seems too complicated, provide a hole in your end-bells/bearing support and place it your thermocouple. Load the machine, run it during a duration T, stop the motor, quickly measure temperature by sliding inside the hole your thermocouple, remove the thermocouple when done and then run the motor again for another T... this is not accurate but that is better than nothing.
Hope this helps,
Guillaume
The best way is to use a surface mounted PTC. please check this link
http://www.littelfuse.com/products/resettable-ptcs/surface-mount.aspx
Hello Hany,
How can you use PTC for temperature measurement?
Can you deploy thermo-graphic camera (IR) and try image processing techniques to study the temperature profiles on the surfaces?
Hi @Arun Areekkare Divakaran ,
Thanks for your suggestions.
I need to monitor the temperature of magnets which are in the rotor (situated interior). If I want to monitor the magnet temperature rise with IR camera, I need to test the motor with outer casing of motor removed. This can cause mechanical misalignment which is undesirable.
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