Why rare-earth-free EV motors are difficult to build

To understand the modern electric vehicle (EV), it helps to look beyond the touchscreen dashboard, the battery skateboard, and the software updates delivered over the air. Deep inside the powertrain is a component that has changed relatively little in concept since the late 20th century: the permanent magnet synchronous motor (PMSM).

Many EVs, whether family hatchbacks or performance sedans, use strong permanent magnets fixed inside a rotating rotor. Those magnets are made from critical rare-earth elements, primarily neodymium (Nd), dysprosium (Dy), and praseodymium (Pr). They help give the motor its high power density, rapid acceleration, and efficiency within a compact, lightweight package.

A cutaway view of an electric vehicle traction motor showing the rotor, stator, and copper windings.

They’re also a significant supply-chain and geopolitical vulnerability. China dominates rare-earth refining and the production of finished neodymium-iron-boron (NdFeB) magnets used in high-power motors. A disruption at either stage could affect EV production worldwide.

In Bengaluru, India’s deep-tech hub, startups including Vimag Labs, which sells under the Volektra brand, and Chara Technologies are developing rare-earth-free electric motors. Magnet-free motors already exist, and automakers including BMW and Tesla use them. What hasn’t yet been achieved at scale is a rare-earth-free motor that matches the torque, size, efficiency, and cost of a comparable permanent magnet motor.

There’s no permanent magnet in Vimag’s rotor. Instead, the magnetic field normally supplied by a magnet is generated on demand by copper windings, powered through a contactless coupling, and adjusted in real time by control software. A motor that relies on copper, steel, and conventional power electronics could, in principle, be manufactured end to end in India. The goal is to reduce dependence on China’s rare-earth supply chain while addressing a significant industry challenge.

The underlying engineering is more nuanced than the headline suggests. The motor topology Vimag is using isn’t new. What the company claims as its own is a specific method of transferring power into a rotating rotor without brushes, along with the control system that manages it.

Part 1 of the article examines the motor architecture, why companies are pursuing this approach, and the engineering challenges involved in replacing permanent magnets. Part 2 will look at how Vimag’s excitation and control systems work, where the technology may be most practical, and which performance claims still require independent validation.

What Vimag Labs built

Start with the marketing term, then set it aside, because it obscures the engineering. A “virtual magnet” or “software-defined magnet” isn’t a new class of physics. It describes what happens when a fixed permanent magnet is replaced with an electromagnet whose strength can be varied by controlling the current through it.

In electrical-machine terms, the VMSM is a wound-rotor synchronous motor. It’s also referred to as an externally excited synchronous motor (EESM) or a wound-field synchronous motor. These names describe the same basic idea. The rotor carries coils of copper wire rather than blocks of magnetized rare-earth alloy. When direct current passes through those coils, they become an electromagnet and produce the rotor field needed to generate torque. Switch off the current, and the rotor field disappears.

The patent Vimag announced in July 2026 reveals the company’s specific approach. It’s roughly titled “A Robust Rotating Transformer Excited Synchronous Motor and Its Control.” Two phrases in that title summarize the design. “Rotating transformer excited” describes how the company transfers current to the moving rotor without physical contact. “And its control” indicates that the control algorithms are treated as a central part of the invention.

Vimag’s public description aligns with this. The company says the motor uses copper coils and steel, with power transferred to the rotor contactlessly inside the motor rather than through brushes or slip rings. Firmware controls the coils as electromagnets and adjusts their field while the motor is running. The design is brushless and slip-ring-free. Because the field is controlled through software rather than fixed by a physical magnet, Vimag says the motor’s behavior can be tuned through software and potentially updated over the air.

Vimag Labs is a Bengaluru-based deep-tech startup founded by Manish Seth and Piyush Desai in 2025, although the company traces its development work to the 2020 pandemic. In 2026, it raised approximately $5 million in a round led by Accel, with Chakra Growth Fund and Thinkuvate participating. It holds five Indian patents and says it’s testing the technology with electric two-wheeler, three-wheeler, and passenger-vehicle manufacturers in India, as well as at least one European Tier 1 supplier. Beyond vehicles, the company identifies industrial machinery and HVAC as potential markets.

Why a magnet-free motor became worth building

The reason a small startup can raise money to rethink the electric motor comes down largely to one country and two numbers. China controls roughly 90% of global rare-earth refining capacity and around 94% of the magnets used in high-power motors, according to figures from the International Energy Agency. That level of concentration creates a significant supply-chain risk, and in 2025, the risk became more immediate.

On April 4, 2025, China’s Ministry of Commerce introduced export controls on seven rare-earth elements, including dysprosium, terbium, samarium, gadolinium, lutetium, scandium, and yttrium, along with related compounds, metals, and magnets. Exporters were required to obtain licenses and submit end-use documentation. The effect was immediate.

Chinese rare-earth magnet exports fell by roughly three-quarters in the two months after the controls took effect. Automakers in the United States and Europe struggled to source permanent magnets, and some reduced production or temporarily shut down factories. Even after licenses were granted and export volumes recovered, prices for magnets produced outside China remained elevated, with European prices reportedly reaching as much as six times those in China.

India felt the impact directly. In late May 2025, Bajaj Auto used its quarterly earnings call to warn of what its managing director called a “dark cloud on the horizon” over the continued supply of rare-earth magnets, which he described as essential components for EVs.

By August 2025, the Indian government was telling Parliament that China’s export restrictions had created a supply-chain bottleneck affecting domestic industries, including EV manufacturers. It also said it was pursuing bilateral mineral agreements and overseas asset acquisitions to improve supply resilience. In October 2025, China expanded the controls further by adding more elements and restricting the processing and separation technologies themselves.

That last point helps explain why motor redesign is being considered. India’s problem isn’t a shortage of rare-earth ore. The country has monazite sand reserves along the coasts of Odisha and Kerala. The challenge is refining the material and manufacturing finished magnets, both of which are expensive, environmentally demanding, and difficult to establish at scale. Vimag’s founder has made this argument directly: the principal bottleneck is refining rather than mining, and building domestic refining capacity would be a slow and costly process.

There are two main ways to reduce that exposure. One is to build a complete domestic rare-earth supply chain, which would be a long-term industrial undertaking. The other is to develop motors that don’t require rare-earth materials at all. Vimag is pursuing the second approach, and it isn’t alone. A wound-rotor motor can be built using copper, electrical steel, and power electronics, all of which India already produces or could manufacture using existing industrial capacity.

The engineering problem: magnets are hard to replace

If magnet-free motors were simply better, the industry would already have adopted them. It hasn’t, because replacing permanent magnets involves genuine engineering trade-offs rather than simple resistance to change.

The dominant traction motor today is the permanent magnet synchronous motor (PMSM), usually in an interior permanent magnet (IPM) configuration. The rotor contains magnets, typically made from neodymium-iron-boron, that produce a strong, constant magnetic field without requiring electrical input. That’s the principal advantage.

The magnets provide rotor flux without consuming current or generating heat in rotor windings. This gives PMSMs high torque density and efficiency in a compact package, which is particularly valuable when fitting a motor into a wheel hub or beneath a scooter seat while trying to maximize battery range.

Neodymium provides the base magnetic strength. Praseodymium is often added to improve resistance to demagnetization, while dysprosium and terbium help the magnets retain their field at the high temperatures reached by traction motors under load. Without them, a magnet that performs well during bench testing can weaken or partially demagnetize as the motor heats up. This thermal requirement is one reason cheaper ferrite magnets aren’t a direct substitute. Ferrite and iron-nitride alternatives exist, but they’re generally heavier, produce less torque, and are more susceptible to demagnetization.

A wound-rotor motor removes both the permanent magnet and the associated rare-earth dependency, but it also introduces several engineering challenges.

The first is delivering current to a rotor spinning at several thousand revolutions per minute. A permanent magnet requires no power supply. A wound rotor needs a continuous supply of direct current for its coils. The traditional solution uses slip rings and carbon brushes, which maintain electrical contact with the rotating shaft. Brushes work, but they wear out, require maintenance, produce debris, and limit the motor’s suitability for sealed or harsh environments. Eliminating the brushes while maintaining electrical power transfer is a central design challenge for modern wound-rotor motors.

The second challenge is efficiency. The excitation current used to energize the rotor coils consumes power and generates heat in the rotor windings, a loss that a permanent magnet motor doesn’t incur. Studies comparing the two topologies for EV applications generally find wound-rotor machines slightly less efficient than equivalent interior permanent magnet motors, particularly at high speeds, and more demanding in terms of cooling.

One detailed design study involving a continuous-duty compressor found that the wound-rotor motor had to be approximately 87% longer than the reference permanent magnet motor to produce the same continuous torque using stator cooling alone. Its peak efficiency was also a few percentage points lower. The conclusion was clear: achieving high continuous torque from a wound-rotor motor without substantially increasing its size requires effective rotor cooling.

The third challenge is control complexity. A permanent magnet motor primarily requires control of the stator current. A wound-rotor motor requires control of both the stator current and the rotor field current, and the two interact. Determining the optimal combination across the full operating range of speed and torque is more complex than the equivalent control problem in a PMSM. It must also be managed continuously, in real time, by an embedded controller.

This is the area Vimag is treating as part of its intellectual property, and it’s a logical place to concentrate development. The control system will largely determine whether the wound-rotor design can offset its inherent disadvantages in efficiency, cooling, and complexity.

Part 2 of this article will examine how Vimag transfers power to the rotating rotor, how its control system creates the adjustable magnetic field, and whether the technology’s advantages can offset its efficiency, cooling, and cost challenges.