New regenerative braking process receives patent

A Purdue researcher has patented a process of collecting a small vehicle’s energy in an ultracapacitor through regenerative braking. The lighter ultracapacitor can store energy better and for longer periods than a typical vehicle battery, which makes it ideal for providing additional energy when it is needed most, such as during acceleration.

“With the ultracapacitor, I can add the additional energy during acceleration without using the batteries, and the coasting is done by the batteries,” said Athula Kulatunga, professor of electrical engineering technology. “During the deceleration, we absorb the energy back into the ultracapacitor. It can stow energy very quickly and release energy very quickly. A battery can’t do that; a battery is pretty slow.”

Kulatunga’s initial work with this process was with an electric tricycle, which he said was perfect for his research needs. The data his team members collected and the process they perfected can now be used in a greater variety of areas.

Kulatunga’s process is unique for two reasons: the configuration of capacitors to maximize energy absorption and the placement of the motor in the vehicle’s wheel. The patent also covers an attachable pedaling mechanism that can help generate electricity and drive the system.

With the motor in the wheel, the system does not require gearboxes or a shaft to run from the engine to the wheels. This streamlined process helps eliminate even more energy loss.

This technology, Kulatunga says, is especially good for small vehicles, such as the three-wheel taxis with two-stroke engines used in some Asian countries. If the taxis were converted from the inefficient, oil-burning engines to the ultracapacitor and battery configuration, they would run cleaner and still serve their intended purpose.

Kulatunga suggests the technology can also have military applications as well.

“You may have a weapon or radio signal a soldier launches every once in a while. When you need a burst of energy, this particular design helps to generate high power for short time, and you don’t have to carry large pack of batteries.”

Working prototypes are available for demonstration and commercialization. At the same time, Kulatunga is expanding his research. The next step is creating a vehicle whose wheels can be driven by separate motors.

“Based on this work, we have developed an electrical differential, and a Ph.D. dissertation has been written on that, where each wheel is driven individually,” Kulatunga said.

The research that supports this patented process was completed in the Power Electronics Development and Applications Lab (PEDAL) at Purdue University, which is directed by Kulatunga. Vehicle electrification related research at PEDAL is funded by General Motors and John Deere companies.