The eRTS (right) contains the wireless mote temperature sensor unit located close to the magnet in the EV motor and the wired transducer element.
A German automotive supplier has unveiled a new technology to measure the temperature inside permanently excited synchronous motors, which are used in electric vehicles (EVs), directly on the rotor for the first time.
Unveiled by Continental, the product is called the e-Motor Rotor Temperature Sensor (eRTS). The innovation is expected to lead to more powerful, low-cost, and sustainable electric motors.
The company claims that the eRTS delivers more precise measurement results than the current software-based temperature simulation with a tolerance range reduced from 15 to just three degrees Celsius.
It’s also being highlighted that the reduced tolerance from 59°F (15°C) to only 37.4°F (3°C) enables more cost-efficient use of rare earth elements and increases potential vehicle performance.
With its usage, the manufacturers can reduce the amount of rare earth elements used to increase the magnets’ heat resistance and improve potential motor performance, which also means greater sustainability. The eRTS is one of several sensor technologies for EVs developed by the E-Mobility Sensors (EMS) product center.
“With less resource consumption and lower costs, eRTS sensor technology is advantageous to current solutions,” said Bin Huo, head of the Passive Safety and Sensorics (PSS) segment in Continental Automotive. “This innovation shows that investing resources and focusing expertise in our product center were the right decision. We will continue to successively expand our EV sensor portfolio.”
Continental highlighted that rotors operate under extreme temperatures of up to 302°F (150°C). Therefore, monitoring temperature control in EV motors is significant.
Heat development is currently measured based on the information from the stator temperature sensor, phase current measurements, and environmental variables.
This comes with a tolerance range of up to 59°F (15°C). To protect the magnet from demagnetization due to excessive temperature, expensive rare earth elements are used to cover the entire tolerance range and ensure the magnet is heat-resistant, according to a press release.
It’s also being claimed that with greater measuring accuracy, reducing the tolerance range to 37.4°F (3°C), manufacturers get multiple options for permanent magnet synchronous EV motor design. As companies can reduce the use of rare earth elements, this will significantly reduce the cost of EVs.
Another interesting variable is the possibility of improving motor performance by pushing the limits of the tolerance range, according to the company.
Widely used in EVs, Permanent Magnet Synchronous Motors (PMSM) are known for their high efficiency and performance. The design features a rotor with permanent magnets and a stator with windings. Known for offering high torque at low speeds, these motors also deliver smooth and quiet operation.
Christoph Busch, who heads the product center, revealed that the company’s E-Mobility Sensors product center aims to increase efficiency and sustainability in electric vehicles.
Busch underlined that the eRTS technology is a good example of this: reducing the use of rare earths contributes to a more sustainable supply chain, especially given that the number of EVs is expected to greatly increase in the coming years and decades.
“In combination with other sensor technologies, such as the e-Motor Rotor Position Sensor, it can even act as a system solution to create synergies that can save car manufacturers money and effort.”
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