Magnet free electric motor

[mdolan92869]

Saw this article this evening. Hope it pans out, sounds like a nice little advancement in electric motors.

https://newatlas.com/automotive/mahle-magnet-free-electric-traction-motor/

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[ChasingCoral]

Saw this article this evening. Hope it pans out, sounds like a nice little advancement in electric motors.

https://newatlas.com/automotive/mahle-magnet-free-electric-traction-motor/

That could also be a way to increase efficiency. At highway speeds one of the two motors could be allowed to free-spin. If one motor has lower gearing , the higher gearing motor could be used to maintain speed, kicking in the second motor as needed for acceleration or climbs.

 

[CHeil402]

The article makes it sound like this is a completely new thing, but rail traction motors have been using induction motors for a while...

https://en.wikipedia.org/wiki/Traction_motor

 

[CHeil402]

That could also be a way to increase efficiency. At highway speeds one of the two motors could be allowed to free-spin. If one motor has lower gearing , the higher gearing motor could be used to maintain speed, kicking in the second motor as needed for acceleration or climbs.

There's a trade off here. Permanent Magnet (PM) motors can provide regenerative braking much quicker than induction motors can. In a PM motor, all you need to do is switch the connection orientation and instead of generating rotational output, you can generate electricity (simplifying a bit). You only generate power if you're moving metal through a magnetic field. In an induction motor you'll need to build that field yourself and when you need to change modes (from power to brake and vice-versa) you need to reverse that magnetic field which takes time (on the order of about 500 ms).

In trains where the response time isn't a huge issue and mode changes are much less frequent it makes sense to get the efficiency benefits. But when you're driving your EV, half a second from pressing the brake to the brakes being applied would be noticeable and likely would require the car to use friction brakes first and then blend in the regenerative brakes.

It can be done, but much like every other engineering decisions, there are pros and cons which need to be weighed.

 

[ChasingCoral]

There's a trade off here. Permanent Magnet (PM) motors can provide regenerative braking much quicker than induction motors can. In a PM motor, all you need to do is switch the connection orientation and instead of generating rotational output, you can generate electricity (simplifying a bit). You only generate power if you're moving metal through a magnetic field. In an induction motor you'll need to build that field yourself and when you need to change modes (from power to brake and vice-versa) you need to reverse that magnetic field which takes time (on the order of about 500 ms).

In trains where the response time isn't a huge issue and mode changes are much less frequent it makes sense to get the efficiency benefits. But when you're driving your EV, half a second from pressing the brake to the brakes being applied would be noticeable and likely would require the car to use friction brakes first and then blend in the regenerative brakes.

It can be done, but much like every other engineering decisions, there are pros and cons which need to be weighed.

Agreed. This is one of the reasons it might make more sense to use this technology for one of the motors rather than both.

 

[JamieGeek]

There's a trade off here. Permanent Magnet (PM) motors can provide regenerative braking much quicker than induction motors can. In a PM motor, all you need to do is switch the connection orientation and instead of generating rotational output, you can generate electricity (simplifying a bit). You only generate power if you're moving metal through a magnetic field. In an induction motor you'll need to build that field yourself and when you need to change modes (from power to brake and vice-versa) you need to reverse that magnetic field which takes time (on the order of about 500 ms).

In trains where the response time isn't a huge issue and mode changes are much less frequent it makes sense to get the efficiency benefits. But when you're driving your EV, half a second from pressing the brake to the brakes being applied would be noticeable and likely would require the car to use friction brakes first and then blend in the regenerative brakes.

It can be done, but much like every other engineering decisions, there are pros and cons which need to be weighed.

However when driving an ICE car we must also account for the time it takes to move ones foot from the gas to the brake. I'm guessing 500ms is likely close to that time.

Thus people may not even notice a 500ms delay before regen kicks in.

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