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Crowdfunding drive for high-torque motor hits target in 2 weeks

18 May, 2020

A Kickstarter crowdfunding campaign to help finance the production of “the world’s highest-torque motor” has exceeded its $30,000 target less than two weeks into a four-week campaign. Texas-based Linear Labs hopes to start deliveries of its 1.4kW, 15Nm (continuous), 3.4kW, 50Nm (peak) Honey Badger motor in December 2020.

The company claims that the four-rotor permanent magnet motor – part of its Hunstable Electric Turbine (HET) family – produces more than twice as much torque as other designs of a similar size, while operating at a higher efficiency (up to 94% or more) across the speed range up to 900 rpm. The 5.2kg motor has a diameter of 175mm and a height of 55mm. It uses “the world’s first magnetic tunnel” to surround a toroidally-wound internal stator, thus converting all of the magnetic and electric fields into torque.

There are no end-windings, so all of the copper contributes to producing torque, and all of the magnetic flux is concentrated in the motor to maximise torque production. Toroidally-wound coils are said to maximise the stator slot fill factor, achieving around 90%, compared to about 70% for other designs.

The circumferential-flux motors are designed principally for use as wheel-hub motors to power vehicles such as electric bikes and scooters, but they could have other uses. They operate from 48–72V DC supplies and can be cooled using air or liquids. The basic design uses standard ferrite magnets, but rare-earth materials can be used to achieve higher performance. Simple, low-cost control electronics can be built into the motor, or located externally.

Linear Labs claims that its motor is the only one that can continue to operate with multiple shorted coils. This is a result of the “unique” stator design that allows the motor to operate as a three-, six- or 12-phase machine – with the ability to switch between phases on-the-fly. The coils can be connected in multiple phase configurations electronically.

The motor’s coils cannot vibrate and short out causing failures that would need replacement or rewinding for other machines. At the end of their lives, the motors are designed to be recycled.

Linear Labs claims that its Honey Badger motor will deliver twice as much torque as rival machines

The low-noise motors are said to be easy to manufacture, without needing specialised tools. A potted design means that they can operate underwater without needing additional sealing or protection.

Linear Labs was founded in 2014 by Brad Hunstable and his father, Fred. Last year, the company raised $4.5m to help develop and market their HET technology, which is protected by more than 75 issued and pending patents.

The company is creating a “dark” factory in Fort Worth, Texas to manufacture and assemble its motors, using rapid manufacturing technologies that will reduce waste. It claims to have the lowest material wastage of any motor technology, with less than 5% wasted in the manufacturing process.

Linear Labs is planning to add data-collection facilities and AI-based controls to its machines.

The company says while it working with large companies to fulfil its vision of smarter energy, it also receives thousands of requests from smaller companies and enthusiasts around the world. “We firmly believe in democratising our class of motors for all,” it says, and “want to use Kickstarter to bring the HET class of motors to as many people as possible”.

The Kickstarter campaign has attracted more than 30 backers, one of which has pledged at least $9,995, for which they will receive two of the motors, two tee-shirts, and the chance to meet Linear Labs’ CEO Brad Hunstable.

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