On September 1, ZF Friedrichschafen, Germany, announced it had developed an ultra-compact electric motor that does not require magnets. This of course is not new as there are several existing ‘magnet-free’ motors, known as externally or separately excited synchronous motors (EESM/SESM). What is unique about ZF’s design is the motor transmits energy for the magnetic field via an inductive exciter located within the rotor shaft, hence, aptly named In-Rotor Inductive Excited Synchronous Motor – I2SM.
Possible motors market disruptor?
ZF’s I2SM’s compact design allows it to maximise power and torque density, enough to rival the output of permanent magnet synchronous motors (PMSMs), which currently make up over 80% of the motors market. Besides this, the absence of permanent magnets in the motor means it is more sustainable, as permanent magnets are heavily reliant on rare-earth elements which have to be mined, cutting CO2 emissions by up to 50% according to the manufacturer.
Image credit: ZF