Ramkrishna Forgings and ePropelled tie up to manufacture eAxles for light EVs

Kolkata based automotive supplier Ramkrishna Forgings Limited (RKFL) and Massachusetts based technology company ePropelled have joined hands to develop eAxle products based on ePropelled’s patented Dynamic Torque Switching^TM (eDTS) technology.

Based on preliminary input from automotive manufacturers, ePropelled and RKFL have developed product specifications for motors, controllers, and software for propulsion systems up to 15kW for the motorbike, three-wheeler, and light four-wheeler markets.

“As large markets like India look to increase EV adoption to reduce pollution and increase energy efficiency, the EV market has been restricted for too long by inefficient motors and the size and cost of batteries,” said Naresh Jalan, Managing Director at RKFL. “By collaborating with ePropelled, we can create a compelling, next-generation propulsion system for manufacturers to provide them with varied options when selling motorbikes, three-wheelers, and light four-wheelers in the Indian market.”

eDTS is an electric propulsion technology for electric vehicles (EVs) that claims to use battery power much more efficiently, allowing OEMs to reduce the battery pack size by at least 15%. In a recent interaction, Nick Grewal – CEO of ePropelled shared that unlike conventional motors, eDTS uses a switch matrix to link the windings of the motor to the invertor. Based on the input from the control system, the switch matrix connects the windings in a series, series-parallel combinations, or all in parallel. Among others, this manages the control of the induced back electromotive force (back EMF), current draw and density, and magnetic flux linkage, resulting in switching the torque, speed range, and constant power range.

The eDTS system comprises three main components –

1. eDTS motor, i.e. a brushless permanent magnet synchronous machine

2. power electronics drive that includes a high voltage inverter and a control system that automatically selects the most efficient operation mode based on vehicle demand

3. an electronic switch matrix that links the many windings of the motor to the phases of the drive. The patent combines the switch matrix with sophisticated software, known as Adaptive Shift Maps.

Impact on the overall system efficiency

ePropelled says that its technology allows the electric motor to provide high torque at low speeds without drawing high current from the batteries. It also provides high speeds at low torque levels without using deep field weakening and at much reduced winding losses, thereby increasing the efficiencies throughout. This technique utilizes the motor magnets and the motor windings optimally and improves the overall drive cycle efficiency, allowing the range of the vehicle to increase by at least 15%.

“Most motors’ highest power efficiency is only available in a very narrow band (a small island we refer to as a “sweet spot”) on the power map. eDTS allows vehicles to operate at maximum efficiency at a much wider efficiency band (much larger islands) on the power map”, adds Nick.