Electric motors used in EVs have leaned on rare-earth permanent magnets for their power density, but that reliance locks manufacturers into a volatile, geographically concentrated supply chain with a heavy extraction footprint. Engineers have spent years exploring magnet-free alternatives, from induction to reluctance to wound-field synchronous designs, each trading magnet dependency for a different set of electrical and thermal challenges. This piece traces that trade-off from first principles through to Magnetless’ UESM, an electrically excited motor built to remove rare-earth dependency without pushing the performance penalty into cooling, control or manufacturing.
Understanding Magnet-Free Motor Technology
Magnet-free motors generate torque by energizing stator windings to create the working magnetic field, rather than relying on a magnetized rotor. Reluctance machines, for instance, pull a shaped ferromagnetic rotor toward the path of least magnetic resistance [1].
These approaches don’t share a single performance profile: reluctance torque depends on rotor geometry and precisely controlled stator current, while electrically excited rotors trade that geometric dependence for field control at the cost of the power needed to energize it. The real engineering question, then, isn’t whether a motor contains magnets, but whether its electromagnetic design, control strategy and thermal limits can deliver the torque and efficiency a vehicle needs without them.
The Challenge of Magnet Dependency
Rare-earth permanent magnets pack high energy density into a small volume, but that density comes bundled with exposure to a tightly concentrated global supply chain. The U.S. Department of Energy flags geographic concentration, geopolitical sensitivity, import reliance and price volatility as resilience risks running through NdFeB magnet supply chains that feed EV motor production [2].
That exposure isn’t just a sourcing headache. Volatile rare-earth input costs complicate long-term pricing and production scale-up, while the extraction, separation and magnet-manufacturing steps add their own environmental and processing burden. Research into rare-earth permanent magnets points to limited supply, environmental concerns and market volatility as structural issues running through the supply chain [3]. Any motor architecture built around these materials inherits their constraints, however well the motor itself performs on the test bench.
Maximizing Motor Performance Without Magnets
Removing magnets doesn’t automatically preserve performance. Reluctance and wound-field machines need higher current to produce the same torque, which raises I²R losses and turns continuous-output capability into a thermal-design problem rather than a materials problem. Rare-earth-free EV motors consequently depend on control and cooling strategies that manage that heat without letting torque ripple, noise or efficiency slide [4]. Design, manufacturing and materials advances can offset, and in some cases close, the performance gap that comes with removing rare-earth magnets [1].
Manufacturing deserves the same scrutiny. Eliminating magnet fabrication and assembly removes a genuinely complex production step, but some reluctance geometries demand tighter air-gap tolerances to hit the same performance. The strongest case for a magnet-free motor is one where removing magnet-related complexity doesn’t just relocate that cost and risk into thermal hardware or precision machining elsewhere in the build.
How Alternative Designs Surpass Traditional Motors
Not every magnet-free topology is automatically cooler or more efficient than its permanent-magnet counterpart; since these designs run higher current for equivalent torque, their performance hinges on pulling heat out of copper and active steel fast enough to avoid derating, an engineering trade-off rather than a built-in penalty. IEEE’s assessment is that rare-earth-free designs have to be judged across power density, cost, manufacturability and overall performance together, not on any single metric [1].
What removing magnets does unambiguously deliver is the elimination of a high-cost, supply-constrained component and the handling and assembly steps that come with it, simplifying sourcing and cutting the extraction footprint, provided the added cooling hardware and its integration complexity don’t eat those gains back up. Permanent-magnet machines remain the default in most EV platforms precisely because of their power density and efficiency [5]; magnet-free designs only overtake them when thermal, electrical and production choices are engineered together rather than bolted on.
Magnetless: The Integrated Solution to Electrification Challenges
Magnetless treats rotor excitation, cooling, winding architecture, control and manufacturing as one motor system, not a stack of compensating add-ons bolted together after the fact. Electrically generated rotor flux can be tuned to match the operating point in a way a fixed magnet cannot, but generating it also consumes power; without cooling and control designed in from the start, the current needed for magnet-free torque becomes a limiting loss rather than a performance lever. Many externally excited machines solve this by adding a separate rotor power supply, which adds its own complexity [6].
The UESM is built to avoid that trade-off entirely: it delivers electrically excited, magnet-free operation with no additional rotor components and no extra rotor power electronics, running on a standard three-phase inverter. That makes eliminating rare-earth dependency a system-level swap rather than a vehicle-platform redesign, since the motor drops into the same electrical architecture a permanent-magnet machine would occupy.
Concluding Insights on System-Level Thinking in Motor Design
The real unit of innovation isn’t the rotor, the inverter or the cooling loop in isolation, but the motor system they form together. A rare-earth-free design has to manage the extra current and heat that come with generating torque without magnets while still being manufacturable at automotive volumes; optimizing one piece while pushing losses, cost or complexity into another isn’t a solution, it’s a relocation.
That’s why motor choices need to be weighed across power density, efficiency, thermal limits, material exposure and production complexity at once. Rare-earth-free EV motors present a genuine set of trade-offs across weight, cost, manufacturability and performance, not a single specification to chase [1]. The durable path to electrification is an integrated design, one like the UESM, that removes the underlying dependency on rare-earth magnets without simply moving its penalty somewhere else in the system.
Sources
- IEEE Spectrum — spectrum.ieee.org
- energy.gov
- sciencedirect.com
- Machines — mdpi.com
- IDTechEx — idtechex.com
- Electric motors in electric vehicles an overview — felss.com