Ferrstron road-tests a 150 kW ferrite-magnet motor that uses no rare earths

Indian electric powertrain developer Ferrstron Powertrains has road-tested a prototype 150 kW, 400 Nm powertrain in a 2.3-ton multi-utility vehicle. The powertrain’s motor uses ferrite magnets instead of rare earth magnets.

Ferrstron is developing electric powertrains for heavy-duty trucks and buses, high-speed trains and marine vessels, plus generators for direct-drive wind turbines and gensets.

Ferrstron says its motor designs, developed with its proprietary electromagnetic physics simulation technology, achieve 98% efficiency. The motors use an axial-flux, dual-airgap design, windings with in-coil cooling and a multi-phase flux control algorithm. Ferrstron says the on-road test of the fully integrated system brings its core technology to Technology Readiness Level 6 (TRL 6).

Ferrite magnets are abundant but weaker than rare earth magnets in magnetic strength and in their ability to withstand demagnetization. The motor is designed to compensate in four ways:

• generating more overall magnetic flux;
• creating higher armature reaction, so less flux is needed from the magnet;
• reducing the demagnetizing effect of armature reaction;
• using multi-phase flux control to shift the magnet’s internal operating point away from the demagnetization limit.

“This unique electromagnetic balance has been achieved by a combination of innovations in multiple areas—architecture defining magnetic circuit, geometry and placement of key elements within the magnetic circuit, winding with in-coil cooling and finally a proprietary multi-phase flux control algorithm,” said Vishal Sharma, founder and CEO of Ferrstron.

Ferrstron plans to build its product range from stackable motor cartridges. Concept designs, validated in simulation, include:

• a 400 Nm cartridge, used singly or in pairs for up to 800 Nm, for passenger vehicles and light commercial vehicles;
• a 1,100 Nm cartridge, stacked up to five for 1,100 to 5,500 Nm, for medium and heavy-duty trucks, buses and distributed-traction high-speed trains.

“Ongoing discussions with global Tier 1 and OEMs show the desire to eliminate the use of rare earth materials; we are spot on,” said Randolph Toom, Ferrstron’s Head of Global Strategic Partnerships. “We are talking to investors to raise our next round of investment to achieve TRL 8 and start production.”

Source: Ferrstron Powertrains