SKF
Rotor Positioning Sensor Bearing Units
Rotor positioning sensor bearing units are an evolution of sensor bearings, specifically aimed at traction motors in electric and hybrid vehicles. They combine a deep groove ball bearing or cylindrical roller bearing with a rugged multi-pole magnetic sensor ring and optional ancillary sensing for temperature. The unit encodes rotor speed, angular position, and in some variants, direction, feeding these signals to the motor inverter for precise commutation and torque control. This arrangement eliminates the need for a separate resolver or external sensor assembly, reducing the motor’s axial length and component count. The sensor is sealed inside the bearing, protected from oils, coolants, and electromagnetic interference. SKF delivers these units as custom-engineered solutions for specific automotive traction platforms, supporting high-reliability e-mobility.
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Integrated Rotor Feedback
Speed, position, direction from one component.
Compact Motor Design
Eliminates external encoders and mounting flanges.
Protected Sensing Element
Sealed bearing guards against magnet debris, ATF, coolant.
High Temperature Tolerance
Designed for typical traction motor environment (up to 150°C).
EMC Robustness
Magnetic sensors unaffected by inverter switching noise.
Automotive Validation
Developed under IATF 16949 and rigorous OEM durability testing.
Enabling Integrated Traction Motor Designs
With space premium in electric axles, integrating the rotor position sensor into the support bearing frees up axial length for coolant channels or reduces the motor’s overall length, benefiting vehicle packaging and weight distribution.
Data for Predictive Vehicle Health Monitoring
Beyond motor control, the rotor position signal can feed vibration analysis algorithms in the vehicle’s telemetry system, providing a cost-effective path to onboard condition monitoring of the drivetrain.