Relationship between magnetic steel performance and motor performance

 1. Influence of residual magnetism

For a DC motor, under the same winding parameters and test conditions, the higher the remanence, the lower the no-load speed and the lower the no-load current; the greater the maximum torque, the higher the efficiency at the highest efficiency point. In the actual test, the level of no-load speed and the size of the maximum torque are generally used to judge the remanence standard of the magnetic steel.

For the same winding parameters and electrical parameters, the running motor at a relatively low speed will generate enough reverse induced voltage to reduce the algebraic sum of the electromotive force applied to the winding. Therefore, the higher the remanence, the lower the no-load speed and the smaller the no-load current.

Further Reading: What Motors can be Used for NdFeB Magnets?



2. The influence of coercivity

In the process of motor operation, there is always the influence of temperature and reverse demagnetization. From the perspective of motor design, under the specified conditions, the higher the coercive force, the smaller the thickness direction of the magnetic steel can be, and the smaller the coercive force, the larger the thickness direction of the magnetic steel.

3. The effect of squareness

Squareness only affects the straightness of the motor performance test efficiency curve. Although the straightness of the motor efficiency curve has not been listed as an important index standard, it is very important for the continuation distance of the in-wheel motor under natural road conditions.

Because of different road conditions, the motor cannot always work at the maximum efficiency point, which is one of the reasons why the maximum efficiency of some motors is not high and the continuation distance is long. A good in-wheel motor should not only have a high maximum efficiency, but also the efficiency curve should be as level as possible, and the smaller the slope of the efficiency reduction, the better. This will gradually become an important standard as the market, technology and standards of in-wheel motors mature.

4. The impact of performance consistency

Inconsistent remanence: due to the inconsistency of the magnetic flux of each unidirectional magnetic field segment, the torque is asymmetric and the vibration occurs.

Inconsistent coercivity: The inconsistency of the magnetic flux of each magnet will cause the motor to vibrate. This effect is more pronounced for brushless motors.

For more information, please visit https://www.stanfordmagnets.com/.


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