What are the special requirements of silicon steel for EVs’ motors?

What are the special requirements of silicon steel for EVs' motors?

The nature of the magnetic field in motors is continuously varying, so material with the same magnetic properties in all directions is used hence CRNGO or simply CRNO (Cold Rolled Non-Grain Oriented) steel

The silicon steel grades used in electric car EVs motors include M19, M27, M36, M45, and M47. The type of silicon steel used depends on the motor's end usage such as the frequency at which it will operate.

In motors, non-grain-oriented silicon steel sheets are used because of cost considerations. This steel exhibits isotropic properties.

However, in the case of power & distribution transformers, cold rolled grain oriented (CRGO) steel is used which is costly, has high magnetic flux density to an extent of 30% in the rolling direction, and has a low area of the hysteresis loop, lower power loss/cycle, low core losses & high magnetic permeability.

Why can't a single silicon steel block used instead of sheets in motors?

• by using the single block of silicone in the core, there are chances to have an eddy current in the core and because of that, eddy current losses will increase in the motor.

• by using thin sheets of silicone steel in the core we can reduce the eddy current losses in the core, so by doing this we can prevent the eddy current losses in the motor.

•Thin sheets of silicone material are used in the core and sheets are stacked together.

Here are 6 good reasons why don't electric cars have an electric motor inside each wheel:

Weight.

Four motors are heavier than one motor and a transaxle, even with a differential to allow the left and right-driven wheels to turn at different speeds while cornering.

Unsprung weight.

The weight that tracks the bumps in the road costs much more energy to move than the weight that is suspended. Wheels are "unsprung", and motors in the wheels would be unsprung too. You would likely want to put the motor on the chassis and use an articulated transmission axle unless you made the motor incredibly light. You could still have four motors, but they won't be "inside the wheels" as in the question.

Harsh environment.

Wheels tend to get the worst of wet, dust, debris, etc. You'd like to keep this stuff out of your motors. See #2 above for moving the motors inboard.

Control.

You need to control four motors, instead of just one. More complexity. But more control opportunities too. Think torque management in slippery conditions.

Steering.

The motors in the steered wheels would tend to compromise the range of steering motion (because they occupy space), and thus could make the turning circle larger.

Cost.

Four small motors are more expensive than one big motor.

Here are a few reasons why you would put four motors inside the wheels:

• Perhaps a better way to make a performance AWD than one motor and a 4-wheel power distribution system. (Note that most EVs today drive only two wheels…)
• Weight distribution. Gets the motor weight low and distributed. But the battery weight is a much bigger deal…
• Thermal management. Get the heat from the motors out of the body. Not much, but something.