I remember reading a book about motors, and one of the more interesting ones was referred to as a "Printed Pole Motor" IIRC.

This motor had multiple salient poles on the rotor, and they could be re-magnetized as they passed one location of the stator.
This allowed the pole count of the rotor to be dynamically changed by re-printing some of the salient poles to create larger or smaller groups of North or South poles in succession around the rotor.

I think they were intended for very large motors for ball mills or some large mining operations, of low speed, and thus many poles around the rotors.
Also, it was suggested that since the poles could be re-written as the motor ran, there could be theoretically non-integer numbers of poles around the rotor, as they could be dynamically printed to match the required speed.

Google cannot find any information on this...

Did I forget the actual name of this class of motor?