Could smarter mechanical transmissions knock power electronics out of wind turbines, providing a cheaper and more efficient means of coupling the variable energy from ever-shifting winds to the regular waveform of AC power on the grid? They could according to my reporting in MIT’s TechReview today on Viryd Technologies’ bid to exploit continuously variable transmissions (CVTs). If mechanics reclaiming territory ceded to electronics sounds like a technological step backwards, here’s an even more heretical corollary: the same CVTs could also squeeze the power electronics out of electric vehicles (EVs).
That’s the argument put forward by Rob Smithson, CTO for Viryd parent company Fallbrook Technologies and one of the inventors of its clever CVT (dubbed NuVinci in a tip-of-the-hat to the Italian polymath who first dreamed up the CVT concept). “If you look at cost in large car-replacement type EVs today, the cost gets dominated by the battery pack and the motor controls. There’s an opportunity to knock out one of those two with an infinitely variable transmission,” insists Smithson.
Most EV elaborations today, says Smithson, rely on the electric motor to meet the entire dynamic performance envelope of the vehicle, from vehicle speed to torque demand — a feat made possible by hefty power electronics. Swap in a CVT to handle the vehicle speed, however, and the electric motor can operate as a fixed speed variable torque device. “When that happens there’s a tremendous opportunity there to simplify your power electronics and a lot of the attendant cost that goes with that,” he says. For more details, see Fallbrook’s white paper on increased power, speed and range observed in a NuVinci-equipped electric scooter. Continue reading “Could Mechanics Best Power Electronics in EVs?”