Auto supply giant Continental is claiming an industry first with its electric motor heat measuring sensor for battery-electric vehicles that will reduce the use of rare earth elements and save on automaker manufacturing costs.
Its e-Motor Rotor Temperature Sensor (eRTS) claims to deliver significantly more precise measurement results than the current software-based temperature simulation. This reduces the safety tolerance range required by the motor’s magnets and, so, requiring less rare earth material.
E-motor rotors operate under extreme conditions, with operating temperatures of up to 302˚F (150°C). Currently, heat development is not measured directly but calculated based on the information from the stator temperature sensor, phase current measurements and environmental variables.
Continental says this comes with a tolerance range of up to 30˚F (15°C) to protect the magnet from demagnetization while expensive rare earth elements are used to cover the range and ensure the magnet is heat-resistant.
With greater measuring accuracy reducing the tolerance range to 6˚F (3°C), car manufacturers profit from new possibilities and freedom of choice in permanent-magnet-synchronous BEV motor design while saving on rare earth costs.
Its eRTS contains two separate components: The wireless mote temperature sensor unit measures the temperature directly at the target area near the magnet, while the mote draws its energy only from the wired transducer that is connected to the ECU, providing the transducer with its measuring data.
The transducer is located outside the BEV’s motor on the chassis. It is connected to the inverter control, transmitting temperature information through a communication interface. Mote and transducer communicate via Piezo ultrasound, which also provides for the energy supply.
“With less resource consumption and lower costs, eRTS sensor technology is advantageous to current solutions,” says Bin Huo, head of the passive safety and sensorics (PSS) unit of Continental Automotive. “This innovation shows that investing resources and focusing expertise in our product center were the right decision.”
