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Smart rotation angle sensor (magnetic resolver) for EV/HEV drive motor

Smart rotation angle sensor (magnetic resolver) for EV/HEV drive motor

High power density and high efficiency in energy conversion and transmission: This distinguishes permanent magnet motors. That’s why they are the first choice for large electric drives used in electric and hybrid vehicles. For effective and low-friction operation, manufacturers have used reluctance resolvers for permanent magnet drives. However, this solution is associated with negative consequences in terms of cost, ease of installation, temperature range, power consumption and weight and size. Piher offers a very accurate position sensor principle with hollow shaft configuration and high resolution, which eliminates these problems and yet meets all other requirements in terms of economy and performance.

The purpose of such a sensor is to enable an efficient and smooth operation enhancing the comfort by limiting vibrations. In some cases related to mechanical constraints, we have to deal with through-shaft design. One can quote for examples power drives for Electric or Hybrid Electric Vehicles as well as for Electric Power Steering motor. These sensors need to keep a simple and robust design and a restricted number of parts as they are submitted to high vibration levels, a wide temperature range and speeds of several krpm.

Piher offers magnetic sensors as a very competitive alternative to the conventional inductive variable reluctance resolver type sensors. The basics of this solution is a through shaft angular position sensor using one or two Hall-effect probes. These Hall ICs measure the angle of the magnetic field generated by a ring or a disc magnet. The magnetic field angle is shaped in order to meet very demanding accuracy requirements (±1° of electric error).


– The cost !

  • BOM: The cost does not depend nearly on the sensor size.
  • Industrialization: The investment is limited.

– Reinforced robustness against magnetic stray field.

– Scalable design with through shafts from 3mm to 150mm.

– Good robustness against geometrical and application tolerances (rotor axial shift, sensing ICs position, rotation speed, …).

– Accuracy ≤ ±1 electrical degree on the automotive temperature range -40°C to 150°C (equivalent to +/- 0.3% of the stroke in case of an absolute 360° measurement).

– The weight.

– The size (slim).

– Low power consumption.

– Safety: Already redundant (2 probes!) and easy access to multiple redundancy (ISO 26262) whereas a redundant VR resolver is painful!

– Hollow shaft configuration.

– Ease of installation.

– Smallest possible count of parts.

– High reliability in extreme temperature, vibration and shock.


– Ring Encoders replacement alternatives.
– Frameless Resolvers replacement alternatives.

Apps: Pumps, Compressors, Mixing machines, Containers, Boilers, Electric motors, Generators, Transporters, Heaters, Heat exchangers, Refrigerators, Elevators, Reducers, Crushers, Separators, Pressure vessels, Dryers, Diesel engines, Control cabinets, Transformers, Cranes, Hoisting units, Machinery Switches, Controllers, Fuses, Relays, Electromagnets, Batteries, Cables and wires, Measurement devices, plug connectors, Lamp holders, Lamps, Lighting devices, Amplifiers, Controlling systems, Light valves, Servomotors, Measurement systems