A simple sensor could solve a major problem with electric motors
By Areeb Khan
A German student has developed a cost-effective way to measure electric motor temperature using an existing hall sensor. The method could help EV manufacturers unlock more power, improve reliability and reduce their reliance on expensive rare-earth magnets.
Aaj ke time par market mein sabse zyada use hone wale permanent magnet electric motors mein ek aisi problem hai jiske baare mein most of the people aware nahi hote, because brands ke engineering departments ko isse continuously deal karna padta hai, because rotor jabrotate karta hai toh uska exact temperature kabhi bhi accurately pata nahi chal pata. Manufacturer or customers both of these have seen a significant problem. Manufacturer ko pata hota hai that maximum load ke under yeh part 150°C tak heat up ho sakta hai, or agar magnets ka temperature ek critical threshold se upper chala jaata hai, jise Curie temperature kaha jaata hai, so magnets demagnetize ho jaate hai, jiske result mein wo apni most important property completely lose kar dete hai. most concerning baat yeh hai ki motor ko cool down karne ke baad bhi magnets apni original property regain nahi kar paate, because yeh ek irreversible process hai.
What makes rotor temperature measurement so crucial? Agar aisa hota hai, so yahi wo thing hai jo high-end electric sports cars banane wale big brands ke liye most concern thing hai. Aisi situation mein customers ko complete electric motor replace karna pad sakta hai, or electric motors ko replace karna bilkul bhi affordable nahi hota. Rotor ki baat karein so yahan par ek major challenge yeh hai that since the rotor continuously rotate karte hai, so aap iske upper conventionally ek temperature sensor directly attach nahi kar sakte . That's the reason industry mein kaafi years se ek trick use ki jaa rahi hai, jahan software ki help se rotor ka temperature calculate kiya jaata hai. Iske liye stator par lage temperature sensor ka data, current measurements or environmental variable ko consider kiya jaata hai, jiske basis par rotor ke actual temperature ka estimation lagaya jaata hai. Problem yeh hai ki is estimate mein up to 15°C ka margin of error dekha jaa sakta hai. It seems yeh difference kaafi small lag sakta hai, but actually yeh desirable limit se zyada hai, because electric motor mein rotor ka temperature hi practically ek invisible ceiling ka role play karta hai, jo limit karta hai ki motor actual mein kitni power deliver kar sakti hai. Motor ko damage hone ke risk ko avoid karne ke liye, manufacturers theoretically jitne rare earth elements ki need honi chahiye usse zyada quality mein magnets use karte hai. Magnets mein mein rare earth elements ki yeh additional quantity use ki jaati hai so that overly optimistic calculations ki wajah se motor ko damage hone ka risk na rahe. But is approach ki wajah se overall cost bhi increase ho jaati hai, along with China par dependence, because most of these materials China se hi aate hai. Actual temperature ko estimate karne ke instead measure karna, so isse aap safety margin ko adjust kar sakte hai and engine se or zyada performance bhi nikaal sakte hai without spending extra on critical materials. Yahin par Continental or ZF jaise world-class suppliers ka role dekhne ko milta hai, with both companies following completely different approaches. Continental is fully committed to millimeter accuracy Continental ke solution ki baat karein so, jise 2025 mein "eRTS" ke name se unveil kiya gaya tha, yahan par aap notice kar payenge that this system measures the temperature directly on the rotor for the first time in the industry, instead of estimating it. Is system mein ek small wireless sensore diya gaya hai, jo directly magnets ke paas position kiya gaya hai. Other than this, chassis par ek fixed receiver unit bhi di gaya hai, jo inverter se connected hai and sensore se wirelessly temperature data receive karta hai. Is direct measurement ki wajah se, margin of error jo usually 15 degree tak hota tha, abb reduce hokar sirf 3 degree reh gaya hai. Iska practical benefit dekha jaa sakta hai ki manufacturers abb much more accurately calculate kar payenge each magnet ko actually kitni rare earth ki requirement hai, instead of applying a generic safety margin. ZF is a prime example on Artificial Intelligence ZF ke approach ki baat karein so, jise TempAI" name diya gaya hai and which was also unveiled in 2025, it solves the same problem but in a completely opposite way, without adding anything extra. Yahan par artificial intelligence based temperature model diya gaya hai which engine ke behaviour ko learn karta hai and temperature prediction ki accuracy ko 15 percent se zyada improve karta hai, as claimed by the company. Previous solution ke comparison mein yeh kaafi cheaper solution hai, jo engine ko up to 6 percent more peak power ke saath use karne ki permission deta hai. Dynamic driving mein efficiency improvements bhi 6 percent se lekar 18 percent tak dekhe jaa sakte hai. Iske example mein Nurburgring track ka ek lap diya gaya hai, jo 20.8 kilometres long hai. Other than this, is solution ki help se development time ko bhi reduce karke sirf kuch days tak laaya jaa sakta hai.
Image source: Motor.es
A final degree project, the most affordable solution that outperforms the previous two. But most interesting thing is while large suppliers aise developments par focus kar rahe hai jinki cost kaafi zyada hai, wahin ek third approach bhi consider ki jaa rahi hai jo comparatively kaafi cheaper hai. Is approach mein electric motors mein use hone wale ek fixed component ko reuse kiya jaa sakta hai, but usse ek completely different task assign kiya jaa raha hai. German engineer Regina Luig ki baat karein so unhone University of Applied Sciences in Caburg mein apne award winning final degree project ke during ek aisa method develop kiya tha, jiske through temperature ko indirectly measure kiya jaa sakta hai. Is method mein rotor ke magnetic field ka use kiya jaata hai, jisse temperature ko directly measure karne ki need nahi hoti. Inki reasoning ke behind ek obvious physical limitation hai, so yahan par understand karna important hai that a conventional temperature sensor ko kisi aise part par attach karna possible nahi hai jo thousands of revolutions per minute ke speed se rotate kar raha ho. But magnets ke magnetic field ko remotely read kiya jaa sakta hai, and interestingly, temperature change hone ke saath yeh magnetic field bhi change hoti hai. Jab magnet heat up hota hai so uska magnetic field weaken ho jaata hai, and jaise hi magnet cool down hota hai, magnetic field abb recover karne lagta hai. Inke system ki baat karein so yahan par Hall sensor ka advantage liya gaya hai, jo already magnetic field mein hone wale variations ko kisi other purpose ke liye measure kar raha hota hai. Abb inhi variations ko ek developed mathematical model ki help se ek reliable temperature value mein convert kiya jaata hai, jisse temperature ko accurately determine kiya jaa sakta hai. Author khud hi aptly explain karti hai ki is problem ke behind actual logic kya hai: engine ka actual temperature jitna accurately pata hoga, utni himore power demand ki jaa sakti hai without engine ko damage hone ka risk. Continental or ZF bhi isi conclusion par pahunchte hai, but existing engine mein pehle se installed sensore ka better use karke. News Source: Motor.es