Updated: Mar 21
May 2018: After a preliminary research into the two wheeler EV segment, a lack of expertise in the powertrain & BMS segment was evident. All players were importing the “heart” of an EV and assembling.
Although, life of the battery pack is not more than 4 to 5 years, the entire cost of the battery pack was being loaded upfront to the consumer. This was creating a big imbalance between the price & performance vis-à-vis its IC engine counterpart.
As a case in point, the consumer would have to shell out almost double than what he would have paid for a 125 CC IC engine moped to get a similar performance.
Evolution of specs
July 2018: The decision was taken to develop the powertrain components, mainly the motor, controller & mechanical reducers from scratch. The technical specification of the powertrain was frozen keeping the below three factors as the guiding rail.
Highest selling IC engine 2 wheeler moped in the country
Swappable subscription based Li ion battery packs
To start the process of Design & development of a 6.5 Kw Liquid cooled PMSM motor with a continuous torque of 30 Nm run by a F.O.C based 250 A sinusoidal controller that would accelerate a 108 Kg kerb weight vehicle from 0-40 in 3.5 S with a top speed of 75Km/Hr. The unit would be powered by a 2.1 KWh swappable battery Pack giving a realistic mileage of around 73Km/Swap.
First to arrive
October 2018: It is always a surreal feeling to lay hands on the core building blocks of the core unit of the EV. It was almost after 4 months of design and simulation and development of dies and fixtures that the raw materials like the stator laminations/Magnets/motor body/motor shaft began to arrive one after the other ready to be assembled and tested. Any major change in system design was pretty much next to impossible at this point of time.
Assembly & Testing of motor
January 2019: Since the motor is at the heart of everything, it had to be assembled, tested and recorded with utmost precision and accuracy. Being a start-up this was a big challenge considering we did not have any of the high end capital equipment’s usually employed to perform such activities.
However, we were able to compromise for the high end machineries with our solid experience and pure skilled workmanship in motor manufacturing to ensure no compromise in quality of the product.
The other tricky aspect was to ensure no leakage of coolant from the coolant jacket housed inside the motor. The tolerances of both the water jacket and motor body had to be maintained at high precision to inhibit any leakage.
Finally the motor was tested on bench for 30 Nm using a simple rope & pulley dynamometer for main parameters like current/speed and temperature rise. It should be noted that it’s very important to know which exact parameter is to be tested that would give you a fair idea that your design is working, we were interested in establishing only that and nothing more.
It is easy to get carried away with very high end testing instruments and keep conducting tests only because the instrument can do so. Luckily for us all we had was a rope/pulley/ammeter/tacho and an infrared gun so that we could only focus on whether the motor can carry the maximum load at its highest speed without heating up beyond its limits for an hour when run continuously.