Source: China Electronic Components Industry Association

The world's first motor rotor temperature sensor (eRTS) technology provides a more precise thermal control solution for permanent magnet synchronous motors (PMSMs) than algorithm-based predictions.

• The temperature measurement tolerance range has been significantly reduced from 15°C to just 3°C, enabling more efficient use of rare earth elements and unlocking greater vehicle performance potential.

• Mr. Huo Bin, Global Head of the Passive Safety & Sensors Business Unit at Continental, stated: "This innovation validates our strategic decision to increase R&D investment in EV sensor technology. We will continue to expand our portfolio of EV sensors."

On June 6, 2025, Continental successfully developed a groundbreaking sensor technology—the first in the world to achieve direct temperature measurement of the rotor in electric vehicle permanent magnet synchronous motors. Compared to current software-based thermal modeling solutions, the eRTS delivers significantly higher accuracy, reducing the tolerance range from 15°C to just 3°C. This advancement enables automakers to decrease the use of rare earth elements required to enhance magnet heat resistance while improving motor performance potential, thereby boosting sustainability. The eRTS is one of a series of EV sensing technologies developed by Continental’s Automotive Group EV Sensor Product Center.

Continental’s innovative eRTS technology provides far more precise temperature monitoring for PMSM motors in EVs, surpassing traditional algorithm-based prediction methods.

Mr. Huo Bin, Global Head of the Passive Safety & Sensors Business Unit at Continental, emphasized: "The eRTS technology reduces rare earth consumption and costs for motor production, significantly outperforming existing solutions. This breakthrough confirms the success of our strategy to intensify R&D efforts in EV sensor technology. Moving forward, we will continue to expand our EV sensor product portfolio."

Higher Measurement Accuracy Helps Reduce Rare Earth Usage

EV motor rotors operate under extreme conditions, with temperatures reaching up to 150°C. Therefore, monitoring and controlling temperature fluctuations is critical. Currently, rotor temperature is not measured directly but calculated based on stator temperature sensor data, phase current measurements, and environmental variables, resulting in a tolerance range as high as 15°C. To prevent magnet demagnetization due to overheating, automakers must use costly rare earth materials to cover this wide tolerance range and ensure thermal stability. With the eRTS’s improved accuracy (3°C tolerance), automakers gain new flexibility in PMSM design: the excessive rare earth material originally required for safety margins can now be substantially reduced. Moreover, this technology opens new possibilities for enhancing motor performance—achieving breakthroughs by precisely controlling a narrower temperature tolerance range.

Mr. Christoph Busch, Head of Continental’s EV Sensor Product Center, explained: "The mission of this product center is to improve the energy efficiency and environmental sustainability of EVs. The eRTS perfectly embodies this vision by reducing rare earth usage and building a more sustainable supply chain—especially crucial given the projected surge in EV adoption over the coming decades. When combined with other sensors, such as the e-Motor Rotor Position Sensor, the eRTS forms a comprehensive system solution, generating synergies that significantly reduce costs and development efforts for automakers."

Motor Rotor Temperature Sensor Design

The eRTS consists of two independent components: a temperature sensing unit and a transducer unit. The sensing unit is mounted directly on the target area for temperature measurement, ensuring proximity to the magnets. This wireless sensing unit draws power solely from the wired transducer connected to the electronic control unit (ECU) while transmitting measurement data back. The transducer, located outside the motor, relays temperature information via a dedicated communication interface. Piezo-ultrasound technology enables bidirectional wireless communication and simultaneous power transfer between the sensing unit and transducer.

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