Bangalore-based startup Chara technologies is developing rare-earth free motors for electric vehicles and other applications. We got in touch with the founders, Ravi Prasad, Bhaktha Keshavachar and Mahalingam Koushik, to share more about the relevance of magnet-free motors, the technology they are developing and its market readiness.
What is the relevance of ‘rare-earth elements’ and ‘permanent magnets’ in motor manufacturing?
The high torque, high power density and efficient motors used in EVs today have a variation of the BLDC and the PMSM motors. These motors have permanent magnets in them, which facilitate all the good features of these motors. Rare-earth elements are needed to make permanent magnets.
Which rare-earth elements are used in motors?
The magnets usually used are NdFeB (Neodymium Ferrous Boron) or rarely SmCo (Samarium Cobalt) magnets. The magnets, as the name says, need Neodymium, Samarium and Dysprosium rare-earth elements to make them work.
What are your reasons for making rare-earth free motors?
Rare-earth elements, as the name implies, are not rare. They are present everywhere, but finding the good ores for efficient extraction is where we end up with problems. The useful ores are unevenly distributed across the planet.
Rare-earth elements are expensive, environmentally hazardous to mine and extract, and one country has close to 90% control over the supply chain of rare-earths and rare earth-based products. For a successful and sustainable transition to an electric future, we need to address this problem.
The concept of Magnet-free motors is not new. What are the main reasons the technology has not been commercialized to date?
Correct, magnet-free motors are as old as the discovery of electricity and magnetism.
– The existing magnet-free technology, primarily Induction motors, suffers from low power density and efficiencies and also difficulty in manufacturing the solid copper rotor.
– Reluctance motors, which were originally proposed two centuries ago, have the potential to replace existing motors. The motors suffered from issues of control, torque ripple and noise. Modern power electronic semiconductors, increased processing power, new algorithms and a fundamentally new way of designing and constructing these motors will solve these problems and herald a new wave of motor technology for EVs and other applications.
What is your solution to ending the rare-earth dependency of motors?
There are two ways to end the rare-earth dependency – Replacement with non rare-earth materials and building products without rare-earths.
With better design, modern power electronics and newer algorithms, we can build competitive rare-earth free, intelligent, sustainable and cost-effective motors for EVs and other applications.
What kind of motors are you developing?
We are developing a motor technology that can be used in a variety of applications practically wherever motors are used. The range of applications where our motors are suited are – EV, HVAC, Household appliances, pumps, industrial and machine tools. To give us more focus and to have the maximum effect on energy consumption, we are initially building motors for HVAC and EVs.
What is the working principle behind these motors?
The working principle of the motor is actually very simple. Just like water finds the least resistance path, magnetic flux lines tend to find the least resistance path (reluctance is magnetic resistance).
The stator in a motor is fixed the rotor is free to rotate. As we change the currents in the stator, the flux lines generated by the currents flow through the stator and the rotor to complete the magnetic path. When they do this, they pull the rotor to minimize the reluctance and hence generate the mechanical torque (also known as the reluctance torque).
The trick is to pass the right current (in amplitude and phase) at the right times to generate the maximum amount of torque.
How do the performance and cost of these motors compare to other popular motors like PMSM or BLDC, or induction motors?
The efficiency, torque and power of our reluctance motors match the efficiency of a comparable BLDC/PMSM.
Our motors are about 30-40% cheaper because we do not use the expensive rare-earth minerals in our motors.
What is the current commercial readiness of motors developed by Chara Technologies?
Currently, we have three signed up paying customers.
– The fractional HP HVAC motor has been delivered to the customer and is undergoing testing.
– The product we are developing for Bounce is a 1.5 kW and 3 kW hub motor with a controller for their 2W EVs. The 1.5 kW motor and controller are being field tested now; the final version will be tested this month and is expected to go into production by the end of this year. The 3 kW hub motor is being dyno tested and expected to go into field test next month.
– The 22 kW liquid-cooled, high voltage traction motor (for a 4-wheeler) has finished dyno testing and is now undergoing field testing.
– We are planning to start the initial production of our motors at the beginning of 2023.
This interview was originally published in EVreporter October 2022 magazine, which can be accessed here.
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