China’s recent restrictions on the export of rare earth minerals and magnets have sent India and the rest of the world into a tizzy; it has forced India’s largest carmaker, Maruti Suzuki, to cut production targets for its maiden electric vehicle, e-Vitara, by two-thirds.

Other than finding new rare earth deposits, there are two options before India (and the world): use magnets that do not need rare-earth material; or use gadgets that do not need magnets — all while ensuring there is no cutback on efficiency or production size.

Viridian Ingni Propulsion founder and CEO Sriram Gopal is developing a prototype of an automobile motor using magnets that are free of rare earth material. He uses the ferrite magnet in his ‘permanent magnet-assisted synchronous’ motors. This is a type of permanent magnet made from iron oxide and other metallic oxides.

Sriram Gopal, founder and CEO, Viridian Ingni Propulsion

Sriram Gopal, founder and CEO, Viridian Ingni Propulsion

Viridian has been able to match the efficiency of rare-earth magnets using ferrite magnets. In terms of weight, it can show parity for motors meant for four-wheelers, but weighs 15-20 per cent more in the case of two-wheeler motors. This is because Sriram’s team uses copper, making it heavier in two- and three-wheelers, which are only fan-cooled, and that too only when the motor runs.

In the case of four-wheelers, the efficiency of ferrite motors is higher than that of rare earth magnet-based motors and the weight is comparable, as the motors are liquid-cooled. (Copper can efficiently transfer heat away from the windings, which helps prevent overheating and maintain optimal motor performance; hence more copper is needed in a two- or three-wheeler.)

Cost-wise, too, ferrite magnets from India are a lot cheaper than rare earth magnets from China.

On the other hand, while rare earth magnets can have a magnetic field strength of about 1.4 tesla, ferrite magnets can manage only about 0.4 tesla.

How does Viridian achieve parity with ferrite magnets? “In our permanent magnet-assisted synchronous reluctance motors, the magnetic torque is 30-40 per cent. (‘Reluctance’ is a material’s inherent resistance to the flow of magnetic force, just as ‘resistance’ is to current.) About 70 per cent would be reluctance torque, depending on the motor design and application. Says Sriram, “The reluctance torque helps make up for the lower field strength.”

e-bike motor manufactured by Basil Energetics

e-bike motor manufactured by Basil Energetics

Torque is the measure of force that makes an object rotate around an axis. Reluctance torque is generated because the motor is moving to a position where the reluctance (or resistance) is declining. As ScienceDirect.com explains, “a simple application of this principle is the refrigerator magnet, which is held in place by reluctance force. Because the reluctance along the path of the magnet flux is minimised when the magnet is as close as possible to (in contact with) the refrigerator, the magnet holds its position.”

Sriram also points out that apart from the dependence on China for supplies, the environmental impact needs to be taken into consideration. “To manufacture 1 kg of rare-earth magnet, anywhere between 75 and 130 kg of carbon emissions are caused. For ferrite magnets, 13 kg of carbon is emitted — 6.8 times lower.

What are the challenges Viridian faces in developing ferrite-magnet based motors? Sriram says lack of software talent is a challenge, as the education system is not equipping students for this specialised domain. “The entity that develops the motor must also develop the controller and the software. When you buy rare-earth magnets from China, it comes with the controllers. Here we have to develop the controller from ground up.”

E-rickshaw motor and (right) two-wheeler motor manufactured by Viridian Ingni Propulsion

E-rickshaw motor and (right) two-wheeler motor manufactured by Viridian Ingni Propulsion

A 2022 paper titled ‘Comparative study of non-rare-earth and rare-earth PM motors for EV applications’, published in MDPI’s Energies journal, states that “the permanent magnet-assisted synchronous reluctance motor exhibits excellent features for the EV applications in terms of cost, torque density, efficiency”. The authors recommend the use of these non-earth motors for passenger cars, buses and heavy-duty trucks.

Going magnet-free

The other option for wriggling out of China’s chokehold is to use motors that do not need magnets. The induction motor is an example, and it can be 100 per cent indigenous.

Japanese motor major Nidec says in its website: by definition, induction motors do not use permanent magnets. They operate by inducing a current in the rotor through electromagnetic induction, rather than relying on a permanent magnetic field.

The US Department of Energy is sceptical about induction motors. It says, “Induction motors have high starting torque and offer high reliability. However, their power density and overall efficiency are lower. They are widely available and common in various industries today, including some production vehicles. Because this motor technology is mature, it is unlikely research could achieve additional improvements in efficiency, cost, weight, and volume for competitive future electric vehicles.”

However, Chennai-based Basil Energetics chairman Dr R Ramarathnam has a different view. He says his company has proved that induction motors operating on direct current not only lower power consumption in t portable electric tools, refrigerators and pumps but also lends itself for use in automobiles to cut the use of magnets without losing efficiency.

Basil has demonstrated at a testing facility in Japan that in electric two-wheelers, an induction motor can achieve the same efficiency as a rare-earth magnet-based brushless DC motor (BLDC). In bulk, too, the motor is comparable to its rare-earth counterpart. He says a prototype for four-wheelers can be made.

Ramarathnam points out that induction motors have the added advantage of working at all temperatures. “If the temperature inside the motor goes up to, say, 150-180 degree Celsius, magnets lose their magnetism, which affects the performance of the motor.”

Asked on what metrics Basil compared the induction motor with appropriate electronic controls and the rare earth BLDC motor, Ramarathnam says, “The power-to-weight ratio — we ensured it was the same as in the permanent magnet motor. And efficiency was the same, too. Loss of efficiency would mean that it would consume more power to do the same work.”

Basil achieved this by focusing on the design of the motor. “There tends to be losses in induction motors in the stator parts, the rotor parts or in the winding. We try to reduce those losses by designing the stator slots, rotor slots appropriately.”

(Stators are the stationary parts of a motor that create a rotating magnetic field when energised by an electric current, which then impels the rotor to produce motion.)

Basil tinkers with the frequency of the motor — higher cycles (60 cycles in motors built on US standards) tend to weigh less compared to the lower cycles (50 cycles) seen in Indian motors. The 20 per cent increase in speed will reduce the weight, comparable to motors using rare-earth magnets, he says.

The design assumes that the size and weight of the induction will be similar to those of a brushless DC motor with rare-earth magnets, he adds.

Selecting the proper slot dimensions is key in the design of the induction motor, he says. Basil has a proprietary software for it. “Most others don’t get into this level of detail. They may procure parts available in the market... We design our motor from ground up.”

The lamination design by his team is critical, too. Here, lamination refers to the design of the stator and the rotor using thin stacked sheets of steel rather than a block of metal. This cuts energy loss and maintains the efficiency of the motor.

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Published on June 29, 2025