March 9, 2009
Goal of electric tricycle to capture, efficiently utilize energy
WEST LAFAYETTE, Ind. - |
Athula Kulatunga, associate professor of electrical engineering technology, received support from General Motors to build a plug-in electric bicycle as a learning platform for power electronics and applied research on controllers, charging devices, battery configurations and motor drives.
The result is a tricycle that features a reclining seat, pedals in the front and handlebars on the side for steering.
"The purpose of the tricycle is to conduct research, not to produce or design these for commercial use," said Kulatunga, who directs research in the International Rectifier Power Electronics Development and Applications Laboratory in the College of Technology. "We decided on a tricycle because it is a fun design that also happens to be ideal for performing analysis on power usage."
The bicycle is powered by electric charge and can be ridden on its own or connected to a data-collection test stand, where researchers can analyze power usage and efficiency.
Kulatunga — along with graduate students Sandun Kuruppu and Jeremiah Dole, and undergraduates Robert Murphy, Fred Chou and Ryan Pickens — first built the bike as a standard tricycle. But early this year, the team redesigned the vehicle to give it more stability and better handling.
The bike, which in its former design could top only 20 mph, now can travel up to 35 or 40 mph due to its lower center of gravity.
"It can handle corners and turning much easier now," Kulatunga said.
The tricycle is powered by a brushless DC motor attached to the back wheels, along with lead-acid batteries, which are located underneath the bike. He said attaching the motor to the wheel is more efficient because it provides a direct transfer of power, preventing much of the energy loss that would take place if the motor were placed in the middle of the vehicle.
"When motors are placed in the middle, some mechanical link is necessary to transfer power to the wheel, which consumes additional energy from batteries, and all that energy is lost," Kulatunga said. "If you can generate force on the wheel, it is much more effective."
To improve the energy efficiency of the vehicle, it is equipped with ultracapacitors, which help to capture energy that would typically be lost during such actions as braking.
"An ultracapacitor works to smooth out and absorb much of the energy, which can then be transferred to power the vehicle," he said. "If perfected, ultracapacitors can extend the driving distance of batteries."
The group also is working on a touch-screen display that will be affixed to the front of the bike, which will show data on energy consumption and efficiency. He said the display will be similar to that of a Toyota Prius screen, in which the driver can monitor energy consumption from the engine, electric motor and battery.
Kulatunga said further modifications to the tricycle will be made periodically as he and his students conduct further research. The tricycle also is part of the power electronics course he teaches in spring semester.
"This teaches students to think out of the box and apply what they are learning in the classroom to the real world," said Kulatunga, who this year was named to Purdue's Kauffman Campuses Initiative Entrepreneurial Leadership Academy. "When students work on projects like this, they begin to open their minds to new ideas and innovations, and even the possibilities of entrepreneurship and one day launching a business from their inventions."
The tricycle was built in Purdue's International Rectifier Power Electronics Development and Application Lab, known as IR-PEDAL, which focuses on energy-efficiency-related applied research in three main areas: motion controls, power conversions and audio amplifiers.
Current projects in the lab include working with American Electric Power to study how large power transmission fuses and capacitors behave and why they fail, developing devices to detect and communicate the failing components in the power grid, and researching how to improve the efficiency of brushless, electronically controlled DC motors that could eventually replace mechanically controlled motors.
Writer: Kim Medaris, (765) 494-6998, kmedaris@purdue.edu
Source: Athula Kulatunga, (765) 494-7724, nkulatun@purdue.edu
Purdue News Service: (765) 494-2096; purduenews@purdue.edu
PHOTO CAPTION:
Athula Kulatunga, associate professor of electrical engineering technology, takes a ride on the electric tricycle that he and his students built. They constructed the tricycle as a learning platform for power electronics and applied research on controllers, charging devices, battery configurations and motor drives. The bicycle is powered by an electric charge and can be ridden on its own or connected to a data-collection test stand where researchers can analyze power usage and efficiency. (Purdue News Service photo/Andrew Hancock)
A publication-quality photo is available at https://www.purdue.edu/uns/images/+2009/electric-tricycle-ride.jpg
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