Known as the “man with the largest negative carbon footprint in the world,” Indian-born American electrical engineer Jayant Baliga is the inventor of the insulated gate bipolar transistor (IGBT), a device that enabled the electronics in the now ubiquitous CFL lamp. An alumnus of Indian Institute of Technology, Madras, Dr. Baliga, who won the global energy prize in 2015, was in the city last month to preside over the convocation of his alma mater and receive an honorary doctorate from the institution.
While he has many inventions to his credit, the one that stands head and shoulders above the rest is the IGBT, which functions as a kind of electronic switch.Tiny giant
A CFL lamp needs such a switch as opposed to a tungsten-based lamp. In the latter, energy is lost due to the heating required by the tungsten filament. A CFL lamp works through a gas discharge. IGBTs are used to generate the gas discharge, which lights up the bulb. The IGBT’s other advantage was to allow for electronics to fit into the small volume of the base below the gas tube.
The use of electronics helped bring down the size, as well as the cost, of CFL lamps. Compared to incandescent bulbs, CFL bulbs improved lighting efficiency by 75 per cent. Use of CFL lamps instead of traditional lighting, in the last 25 years, has saved the world 73,000 Terawatt-hours of energy and almost 5.7 trillion litres of gas, and has helped decrease carbon dioxide emissions by 49.5 billion metric tonnes.
Yet it was not easy for this component to be accepted initially, and there were many sceptics, said Mr. Baliga. “I had to convince not only the management at the GE research labs where I worked but even the Chairman of GE Jack Welch. After his buy in, I had to execute the design and fabrication of the device in a manufacturing line resulting to product availability in less than one year,” he said. General Electric then accepted the technology for a range of small appliances (steam irons, space heaters, etc), major appliances (refrigerators, washing machines, microwave ovens, etc), air-conditioning heat pumps, numerical controls for factory automation (robotics), lighting products, and even in their medical products (X-ray, CAT, MRI).
Selling a disruptive technology wasn’t easy. Dr Baliga recalls how it turned out that his product came to impact the entire portfolio at GE:
“One of the Vice-Presidents at GE was trying to create a new product – adjustable speed motor drive for air-conditioning heat pumps. He challenged us at the GE research labs to create a viable technology. In response, I proposed the IGBT and informed him of other potential applications within GE.”
The old or traditional motor drives used induction motors and dampers to regulate the output power to loads such as compressors in air-conditioners. Dampers waste a lot power as heat, making the efficiency only 50 per cent. The IGBT was used to create an adjustable (or variable) frequency power source by using pulse-width modulation. In simpler words, Dr. Baliga says, “Moving from the traditional motor drive to the one based on IGBT is a paradigm shift – from analogue power control to digital power control with a massive increase in efficiency!”Company-wide adoption
According to the scientist, “The V-P got excited and went all the way to the top and informed Chairman Jack Welch. Jack Welch decided to come from his head-office in Connecticut to my labs in Schenectady, New York, to be briefed on this innovation that would impact the entire portfolio of products at GE.” Dr. Baliga says a a 30-minute presentation convinced Mr. Welch. “His reaction was to support my proposed development and commercialization effort. But he embargoed any release of information on the IGBT so that GE could exploit it for its products. This prevented my scientific publications on the IGBT for several years.”
His advice to inventors and entrepreneurs is to get to understand the applications of the innovation. “Only then can it be marketed successfully. It is important to understand the complexities of manufacturing the invention to get it to the marketplace quickly,” he said.
All this happened in the 1970s and 1980s, when venture capital activity in North Carolina was very small when compared with the Silicon Valley. He recalls, “In the 1970s, and 1980s, I worked for a large company (GE) to bring my ideas to the market. In 2000, I began to create start-up companies in North Carolina. Seed funds were available to get the companies going. But even after demonstrating that my ideas worked, it was difficult to get the larger amount of funds to grow my company. So, we ended up with a successful exit by having the companies acquired.”4 start-ups
Dr. Baliga has been successful in founding four start-ups. “Silicon Wireless Corp created a revolutionary super-linear power RF MOSFET for use in cellular base stations. The company grew to 42 employees and was acquired by Fairchild.” Another one, Silicon Semiconductor Corp was started to commercialise his silicon chip set for powering microprocessors inside laptops and servers. This company’s technology was licensed for production by Linear Technologies Inc. A third start-up Micro-Ohm Corp was begun to create a revolutionary TMBS rectifier used in solar panels and power supplies. It was licensed to Vishay-Siliconix and became their most successful new rectifier product in 25 years, he said. “Giant Semiconductor Corp was created to commercialize my GD-MOSFET technology. This technology was licensed to Alpha and Omega Corp and is also made now by Infineon, Fairchild, and other companies for automotive electronics.”
Dr. Baliga’s 1979 theory relating properties of semiconductors to the performance of power devices resulted in an equation named Baliga’s figure of merit (BFOM). This led to a comparison among semiconductor materials – Silicon, Gallium Arsenide and Silicon Carbide. “This predicted 13.7x enhanced performance by replacing Silicon with Gallium Arsenide which I demonstrated at GE in the 1980s. It predicted 200x enhanced performance by replacing Silicon with Silicon Carbide which I successfully demonstrated at my PSRC labs in North Carolina.”