Spong receives patent for motor-improving technology

ECE Professor Mark Spong, a Donald Biggar Willett Professor of Engineering, has received a patent from the U.S. Patent Office for his invention entitled, "Method and System of Compensating Wave Reflections in Transmission Lines."

Along with co-inventor Romeo Ortega, a professor at SUPELEC outside of Paris, France, Spong developed a method and system to eliminate voltage overshoot in systems that connect alternating current (AC) electric motors to pulse-width modulation inverters. This will solve the problem that occurs when high-frequency voltage pulses reflect between the motor and the inverter, potentially causing damage to the motor and voltage-sensitive devices.

"It’s actually a significant problem in industry," said Spong of the wave reflections. "But we now have a way to compensate the voltage [in the transmission lines] before it gets sent to the motor."

Such an invention will have an impact on companies that rely on AC motors including those that work with heavy industrial machines and those in the chemical, food, and beverage industries.

Although there have been various versions of systems to address the voltage overshoot problem in the past, most have involved either passive filters or impedance matching. Spong said the newly patented technology proves to be very accurate and boasts several advantages, such as not requiring knowledge of the load impedance.

The technology is potentially very cost-effective, as it dramatically extends the life of the motors and allows companies the option of working with less expensive equipment, said Spong. It also provides for a low-cost, self-adapting feature that allows for a modification of waveforms to compensate systems with different transmission line characteristics.

Spong and Ortega started investigating the problem of wave reflections in 2003 after a meeting in France. "It was by coincidence that we started this," said Spong. "But so many companies expressed interest in the technology that we decided to go forward with the patent application."

According to Spong, he has a long-term research relationship with Ortega that has lasted almost twenty years. They typically visit each other at least once a year, and have collaborated together on multiple published papers in the areas of control theory and robotics. An ECE Illinois student and a several students from France have co-authored some of their papers on this problem.

"Because of its implicit recognition of usefulness, getting a patent through is a crowning achievement for any theoretician working in control," said Ortega.

This is Spong’s first patent. "For 24 years I have only been concerned with writing papers and working with students," he said. "So it’s very nice [to receive this credit]. It’s exciting."

As it has just been patented, no company has yet licensed the technology.