Eliminating the Laptop Charging Brick
A Google-backed startup says gallium nitride could make power electronics more efficient.
* Thursday, February 24, 2011
* By Kevin Bullis
A startup called Transphorm has announced a technology that could eliminate the bulky charging bricks that come with laptops and other devices. It could also make data centers and electric cars more efficient.
The company has been developing the technology in secret over the last four years and has raised $38 million so far from investors such as Google Ventures and Kleiner Perkins Caufield & Byers. It will unveil its first products in the next two weeks.
Umesh Mishra, the CEO and cofounder of Transphorm, estimates that 10 percent of the electricity generated in the United States is wasted by power electronics—a broad class of components that change the properties of electricity for different applications. Some power electronics convert high-voltage AC power to lower-voltage DC to run a laptop or a Web server, for example. Others convert DC power from a battery pack in an electric car into AC to run the motor. In addition to wasting electricity, existing power electronics can be bulky, partly they generate waste heat that must be dissipated with heat sinks, fans, radiators, and other components.
Transphorm has developed power electronics based on gallium nitride, a semiconductor that Mishra says wastes far less power than the silicon components used in conventional devices. Not only are these electronics more efficient, but they can do without some of the bulky cooling systems. For example, the company hopes to reduce the size of the charger bricks required by laptops today—or eliminate them altogether by incorporating the necessary electronics into the computer itself. The more compact design is also important for automobile applications, where space is limited and weight is important to fuel efficiency. Mishra says the company believes it can reduce wasted electricity by 90 percent.
One of the first markets for Transphorm will be data centers. The company also hopes to see its products replace the conventional inverters used to turn DC power from solar panels into AC for household use. Transphorm’s inverters could improve the efficiency of solar systems by 2 to 4 percentage points—an impressive figure in an industry that celebrates 1 percent jumps in efficiency.
The possibility of using gallium nitride in power electronics has been known for decades, but producing high-quality versions of the material has been a challenge. That problem, however, was largely solved by researchers who figured out how to use gallium nitride in LEDs, Mishra says. Transphorm has optimized the material for power electronics, and it has developed novel devices (such as transistors), circuits, and complete modules that include all the components needed to replace conventional systems. It’s now developing higher-performance systems under a $2,950,000 grant from the Advanced Research Projects Agency for Energy (ARPA-E).
Transphorm isn’t the only company developing power electronics based on gallium nitride. Other companies working on similar technology include HRL Laboratories, OnChip Power, Efficient Power Conversion, and GaNSystems. The proliferation of these companies is due in part to the shortcomings of conventional silicon devices, which Mishra says are reaching their theoretical limits.
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