Transphorm - Gallium Nitride Power Converters

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 because they generate waste heat that must be dissipated with heat sinks, fans, or radiators.

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, they can also 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.

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The $8.4-million project funded by ARPA-E (earlier post) is creating a 600V GaN-on-Si device combined with sintered interconnects and double-sided cooling. If successful, the device will outperform existing IGBT devices by 3-5 times and enable a roadmap to reduce cost, size and energy losses by 50% for automotive applications within 5-7 years.

The goal is to develop a high power inverter with solid-state electronic switch modules that is significantly smaller and lighter, that works at higher temperatures and that reduces energy lost in the DC to AC inversion process.
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—Robert Schumacher, Ph.D., general director of Advanced Engineering & Business Development​

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