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Switched-Reluctance Motors: Reimagining A Pillar Of Electrification



Application of electric motors is probably more prevalent in our lives than we would have wondered. The motor ecosystem is the lifeline of any mechanical device. Every machine and device, right from a fan to HVACs to industrial turbines to vehicles use electric motors. With rising CO2 levels and growing environmental concerns, there has been a higher adoption of electrification and many government policies are supporting this market. Though applications of motors in industries has existed since decades, new developments have been bubbling in this sector recently. The intelligent motor market is poised to be a $100Bn market by 2024 globally.

Electrification of a vehicle primarily consists of three components — batteries, motors and powertrains. Electric motors are for machines what a heart is for a human body! As the heart is the muscle that pumps blood, oxygen and nutrients around the body, a motor converts electrical energy into mechanical energy through interaction between the motor’s magnetic field and electric current and produces torque that helps a machine in running. The two widely used motors currently are induction motors and BLDC (brushless direct control) motors. All motors have 2 key parts — a stator and a rotor. In an induction motor, the stator is the stationary electrical component consisting of a group of individual electro-magnets which form a hollow cylinder, with one pole of each magnet facing toward the center of the group. The rotor is the rotating electrical component, located inside the stator and consists of a group of electro-magnets arranged around a cylinder, with the poles facing toward the stator poles. An AC motor works by applying alternating current to stator windings, which produce a rotating magnetic field. Because the magnetic field rotates in this way, an AC motor does not need power or mechanical aid to be applied to the rotor. A BLDC motor on the other hand has a simpler design and a higher life span. In this case, the permanent magnet is actually the rotor, and rotates through the current provided by the coils wrapped on the surrounding stator. This rotation is achieved by changing the direction of the magnetic fields generated by the surrounding stationary coils.

Though there is a vast application of motors, India is still heavily dependent on import of motor components and parts that are currently not manufactured in India. At present, there is application of BLDC Motors in most of the use-cases. These motors use permanent magnets, a rare-earth element as a major component, which increases the cost of the motor development considerably. These magnets are usually imported from China and expensive in nature. India is highly import dependent on these resources and will have a significant impact on permanent magnet procurement. Moreover, due to the presence of magnets, these motors cannot function at an extremely high temperature and there is a lack of reliability in their long-term life. The other alternative to a BLDC is Induction Motor, which is not nearly as efficient as the BLDC and consumes more input power and is mainly more usable for high powered machines. The estimated demand of rare-earth magnets in electric motors is forecasted to increase by 20x by 2030. This can lead to supply inflexibility and extreme rise in prices, leading to a high import cost. Also, rare-earth magnet has a high environmental footprint and may be responsible for 25% of material processing related to greenhouse gas emissions.

Chara has revived and reinvented the old technology of a Switched Reluctance Motor (SRM) to make it more applicable and functional. Switched-reluctance motors have many advantages, including low cost and low energy use. They operate by switching currents in the stator windings in response to changes in the magnetic circuit formed by the rotor and stator. The stator of a switched reluctance motor contains windings, similar to a brushless DC motor, but the rotor is simply made of steel that is shaped into salient poles, with no magnets. When the rotor and stator poles are out of alignment, the magnetic circuit between them has a high reluctance. As the stator pole pairs are energized, the rotor turns to align with the energized stator poles, which minimizes the reluctance of the magnetic circuit. Because switched reluctance motors have rotors with no windings or magnets or windings, they have lower inertia and can therefore achieve higher accelerations and speeds than motors with permanent magnet rotors, such as stepper motors. The lack of magnets on the rotor provides other benefits as well — including the ​ability to withstand higher temperatures (less cooling required) and simple, lower-cost construction than permanent magnet motors​. However, their main drawback is they are difficult to control and undergo torque fluctuations. Because the inductance is constantly changing, the position of the rotor must be accurately tracked to compensate for this.

Audible noise is another control difficulty that SRMs face.

Chara plans to overcome the challenges that a switched reluctance motor faces by developing an ​IoT based sensor driven intelligent motor control​. The controller will perform continuous analysis of data both offline and online for data gathering and performance improvement. This data will be cloud-controlled and shared with the manufacturers giving insights into usage characteristics and assisting in quick recommendations of improvements and bug fixes, increasing the performance efficiency of the motor.

Chara’s rare-earth free intelligent switch reluctance motors have a huge application in the EV segment that has been developing over the last few years. India represents the fourth largest automobile market in the world and the second largest two-wheeler market globally. EV is projected to be an INR 500 billion market in India by 2025 where maximum adoption will be in the two- and three- wheeler segment. The use of Chara’s SRM motors is not restricted to electric vehicles and can be widely used in HVACs, defence, home appliances and manufacturing industries. Unlike induction motors that can stop working when one of its phases drops out, the SRM smart motor continues operating because its intelligence automatically takes control and powers the two remaining phases. These smart motors will convert the way a machine runs by bringing down energy consumption and operating costs and shifting the motor ecosystem to a sustainable electron-based technology.

The team has a remarkable pedigree with more than 5 decades of combined experience in the sector. Ravi Prasad has in-depth knowledge in motor engineering and design. Bhaktha Keshavachar, an ex-co-founder of Ezetap has over 25 years of experience in the software engineering space and has been working in the startup ecosystem since the last 10 years. Mahalingam Koushik has been working in the hardware tech space since a decade. The entrepreneurs have built a strong network and have been associated with each other since their college days. Chara’s magnet-free SRM motor brings an indigeneous solution to overcome this problem where they are using IoT and data analytics to improve motor performance. SRM has similar efficiency to BLDC, however, it caters to all limitations of a BLDC motor such as procurement of rare-earth magnet at a high cost and the need of a liquid cooling motor controller to manage heating. The stage that the company is currently in, fits the mandate of CIIE.CO’s investment thesis to support early stage tech driven entrepreneurship. Chara is reinventing an old technology using innovative mechanisms and augmenting its application in the motor ecosystem of India.


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