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21-09-2023 | Electric Engine | Editor´s Pick | News

ZF Develops Compact Magnet-Free E-Motor

Author: Patrick Schäfer

1 min reading time

ZF is developing a new electric motor for series production. The In-Rotor Inductive-Excited Synchronous Motor is a further development of a separately excited synchronous motor.

ZF is developing the In-Rotor Inductive-Excited Synchronous Motor (I2SM) to series production readiness, which does not require magnets. This further developed version of an separately excited synchronous motor (SESM) can thus can reduce losses for the energy transmission into the rotor by 15 % due to the inductive exciter. The energy is transferred to the rotor without contact and a magnetic field is generated there by means of coils. The I2SM requires no brush elements or slip rings. In addition, the rotor is efficiently cooled by circulating oil, as in permanently magnetized synchronous motors.

The space-neutral integration of the exciter into the rotor means that there are no axial space disadvantages. Compared to common separately excited synchronous motors, the innovation requires up to 90 mm less axial installation space, it is claimed. An increase in power density in the rotor leads to improved performance. In addition, the CO2 footprint in manufacturing, which in the case of PSM-E motors arises in particular from magnets with rare earths, can be reduced by up to 50 % and the dependency on supply chains can be reduced.


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