Very Important Development: Motor needs no Rare Earths

Don't you think they will mine for the Thorium alone? Seems to me it would be worth a lot more as fuel than the rare earths are or will have been.

The description of the motor makes me wonder if it is just a model of the ubiquitous shaded-pole AC motor.

There are lots of motors and generators around that have wound rotors and couple to the rotor through magnetic fields. Big AC generators do this, with rotating transformers and bridge rectifiers to excite the rotating field. Synchros often couple to the rotor through a rotating transformer along the shaft, to avoid brushes.

This doesn't sound terribly original.

Magnets are a pretty efficient way to make a magnetic field.

The same argument was raised in the slashdot discussion. Apparently Mahle is doing it a significantly different way that results in higher performance. You'll have to read the slashdot link to understand it.

Wasn't there a diagram that showed RF stimulation?

There has been a lot of press, and investment, in EVs lately. And a lot of press about rare earth shortages. This screams investment opportunity.

Someone else just reinvented the variable reluctance motor. And laminated steel pole pieces. The press releases emphasize how they use STEEL instead of rare earths.

On Friday, 14 May 2021 at 08:18:40 UTC-7, snipped-for-privacy@highlandsniptechnology.com wrote: ...

.. The Tesla Roadster and Model S/X cars used induction motors from day one, in 2009, no rare earths; just iron and copper.

They recently changed one of the two motors to use permanent magnets as they have a bit higher efficiency at low powers. The other is still an induction motor. Tesla did pioneer the use of the Halbach array to reduce the amount of rare earth magnetic material needed in the permanent magnet motors.

Even in the permanent motor designs used by Tesla, BMW and others they are designed such that about 30% of the torque is derived from the variable reluctance so minimizing the amount of rare earths, although it is difficult to do larger amounts and get acceptable noise and torque ripple. Some mild-hybrid cars do use wound rotor variable reluctance motors for low cost.

kw

So far so good but you do have to wonder what they do use to concentrate the magnetic field to a useful level.

We used to make two sorts of mass spectrometer: Soft iron cored ones that could beam switch at a leisurely pace consistent with slow very precise measurements and air cored ones that used a lot more power but could really thrash things around quickly for surveys.

I don't see how they could get the field strength needed to make this work effectively unless they have found a magic form of soft iron core.

On Friday, 14 May 2021 at 10:31:24 UTC-7, Martin Brown wrote: ...

Not sure what you mean by "work effectively".

Most electric vehicle permanent magnet motors have the magnets embedded within conventional silicon steel and a wound stator also using conventional silicon-steel laminations. These are generally known as Interior Permanent Magnet motors. They obtain some 30% of their torque from variable reluctance with the remainder from the permanent magnets.

This development from Mahle seems to be just a modern brushless exciter adapter for electric vehicles. Such exciters for large alternators have been around since the 1950's, it is difficult to see what is new about this design.

kw

Yeah, but every induction motor has 'winding' elements in the rotor (and a shorted winding works well, for AC drive systems).

The trick is, to get the right field geometry, a PERMANENT magnet can be permanently damaged, while a magnetized core can be designed to shape the field and will never age out of spec.

Iron rotors are mechanically better than exotic magnets. The "new" design just uses a bunch of stuff to avoid slip rings (and slip rings are plenty good, IMHO). A smart electric car can tell you when to replace the wear parts, so I'm not seeing this innovation's appeal.

Yes, I agree on slip rings. Hundeds of millions of cars have alternators that use slip rings. They often last longer than the car.

In the old days, hifi's used iron transformers that ofen went past 20KHz.

Some very high power AM transmitters needed power transformers that could deliver high quality voice at very high levels.

For example, WLW at 500 kW, KDKA at 500 kW, VOA’s “Radio Martí” at 100 kW, XERF at 250 kw, and innumerable stations at 50 kW. So there is no problem getting iron cores that operate at high power over a wide frequency range.

The question is how much power is needed in this application, and can they get it in a small enough space to fit in the motor. Apparently they think so.

Motorcycles are usually PM alternators and some are used in cars. I did a crash self-education course in PM alternators and started with one from a Deere rider lawn motor.

I took it to be like a brushless alternator but run in reverse.

it doesn't sound original.

magnetic fields don't take a lot of power to maintain, and using a variable field is a long established way to get efficient speed control in traction motors without varying the supply voltage.

using a variable field in an electronically commutated rotating field motor does seem original though

I'd be surprised if they managed to patent it.