Talking about the Application of Permanent Magnet Materials in Automotive EPS (2)

The motors used in EPS are divided into brush motors and brushless motors:
A brush motor switches the current while the brush and commutator rotate, and can rotate when the power is turned on. The cost is relatively low, but the winding of the brush motor is arranged on the rotor side. As the output power increases, the inertia torque of the motor increases, and the problem of poor steering operation sensitivity needs to be solved.
The brushless motor itself does not have a rectification function, so a built-in angle sensor is required to switch the current of the corresponding angle signal through the circuit, which is complex in structure and high in cost. But the windings of the brushless motor are arranged at the stator side, and the rotor is a permanent magnet. Even if the output power increases, the inertia torque problem can be suppressed.
Permanent magnet materials in EPS motors
EPS has high requirements for the performance, weight, and volume of permanent magnet motors, so the permanent magnet materials mainly use high-performance neodymium iron boron magnets, currently mainly sintered neodymium iron boron. Common grades are 45H, 48H, 38SH, 40SH, 42SH, 48SH, 35UH, etc. In the future, hot pressed neodymium iron boron is expected to replace sintered neodymium iron boron in EPS, but the technology is not yet mature and the cost is still high. Sintered neodymium iron boron is still the mainstream.
Permanent magnet materials can also provide higher efficiency and shorter response time for vehicle EPS. The experimental results show that when using permanent magnets, the response time of EPS can be reduced to 50% of the original, thereby detecting the demand signal for steering more quickly and rotating the wheel and rudder to maintain vehicle stability.
In summary, permanent magnet materials are an excellent choice for automotive EPS. They can provide a stable, efficient, and safe steering response for the vehicle, thereby providing a more comfortable driving experience for the driver. In the future, with the development of permanent magnet material technology and the expansion of application fields, the stability and efficiency of automotive EPS will be further improved.