Makers of electric vehicles, e-bikes, or electric scooters—and the owners who love them—tend to focus on batteries, and how much better their vehicles become as batteries shrink in weight, size, and cost.
But electric motors are the often-overlooked aspect of that equation. Linear Labs says its electric machines could revolutionize automobiles, wind turbines, and air conditioners as well as robotics, drones, and micromobility vehicles.
The Ft. Worth, Texas–based company has invented what it calls the Hunstable Electric Turbine, or HET. The patented HET, the company claims, can generate two to five times the torque of existing motors or generators, in the same-size package. Torque is the amount of work that a motor or engine produces, typically measured on a per-revolution basis.
“We believe we’ve built an entirely new class of electric motors, and that hasn’t happened in maybe 30 years,” says Brad Hunstable, the company’s founder and chairman.
Hunstable was formerly CEO of UStream, a video streaming and hosting company (now known as IBM Cloud Video) that IBM acquired for US $150 million in 2016. Brad’s father and company CTO Fred Hunstable is an inventor and electrical engineer, who worked in the nuclear power industry for Raytheon and Ebasco. And Linear Labs began about five years ago as a father-and-son project. Among its roughly 20 full-time employees, the company counts former employees of Tesla, Daimler, and Faraday Future.
The Hunstables tick off myriad design and technical advantages for their HET, which they define as a 3D circumferential flux, four-rotor permanent magnet motor. Unlike typical designs, the synchronous DC motors have no superfluous end windings, so 100 percent of their copper material goes into energy conversion. A typical motor’s copper content could be reduced by 30 percent, while generating equivalent torque, they say. So for a given torque level, the HET consumes significantly less energy than competing designs.
Company studies of existing automotive platforms, including the Tesla and the Toyota Prius, show that the motors could increase driving range by more than 10 percent; or allow those cars to carry relatively smaller battery packs to deliver equivalent range. The HET itself is spectacularly efficient, generating up to a claimed 150 newton meters (Nm) of torque at just 3,000 revolutions per minute (rpm), in a Prius-size packaging envelope.
The company’s permanent-magnet tech requires no rare-earth metals. The motors generate such robust torque that, in most applications, no gearbox reduction is necessary. The system incorporates a purely electronic transmission, which reduces energy losses and, at production scale, could trim at least 45 kilograms (100 pounds) from vehicle weight. Complexity and costs for engineering and manufacturing drop along with it.
Many electrified vehicles must also integrate a DC-to-DC converter—which boosts or chops voltage to varying levels—to enable a full range of driving speeds under various loads. But because the HET can generate such robust torque at lower rpms, it could also eliminate the boost converter that’s found on every car. Thus, the motors could deliver a domino effect that’s another holy grail of transportation engineers: A smaller, more efficient motor with no geared reduction or DC/DC converter would allow for smaller and lighter batteries, simplified and less-costly controls, and lighter suspensions and other chassis components that underpin those systems.
“The electronics to power motors are often more expensive than the motors themselves,” Brad says.
Linear Labs has begun working with customers, as yet unnamed, to jointly develop applications in electric and micromobility vehicles, robotics, and for HVAC systems. The company says a ride-sharing scooter company asked it to evaluate a Segway Ninebot ES4 motor.
The resulting Segway enjoyed a 50 percent increase in range, and four times the torque, which boosted the vehicle’s top speed and allowed it to climb a steep 20 percent grade.
“You’ll see us in a micromobility application, with air-cooled motors, within one year,” Fred Hunstable says.
The Hunstables add that with 45 percent of the world’s electricity eventually flowing through an electric motor, decisive gains in power and efficiency could have untold benefits in energy savings and performance. One example: The company estimates that, in a large, 8-megawatt wind turbine, the HET could save 80 metric tons of weight, millions of dollars in costs, and lift efficiency by 3 percent.
“We feel we’re part of a smarter, cleaner energy movement, with applications way beyond mobility,” Brad says.
A version of this post appears in the November 2019 print issue as “Startup Promises an Electric-Motor Revolution.”