Industry News: Twice the Torque, Three Times Power Density, Linear Labs Electric Motors

[G. David Felt]

Revolution most commonly starts in the heart of what is to be disrupted. In this case, oil country is where one of the most revolutionary new motor designs is coming from. The minds at the University of Texas in Dallas, Dr. Babak Fahimi and the Renewable Enery and Vehicular Technology Laboratory brings us this new startup "Linear Labs Inc. A Smart Electric Motor Company" who just completed their funding round to allow them to market and produce their flagship motor, the Hunstable Electric Turbine motor.

Currently today's electric vehicle has a high revving horsepower motor with low torque, as an example you can find many electric motors that produce 50 horsepower at 10,000 rpm with 26 lb-ft of torque. The Hunstable Electric Turbine motor produces that same 50 horsepower at 1,300 rpm with 200 lb-ft of torque thus eliminating the need for a gear box as well as other components which in turn reduces cost and complexity.

 

The Hunstable motor while eliminating geared reduction thus being useful for direct drive applications retains the capability to perform at extremely high speeds and maintains maximum efficiency throughout the loading curve.

Let's get into the technical chops of the Hunstable Electric Turbine (HET) motor.

• Permanent magnet circumferential flux 4 rotor motor
• 3D magnetic structure produces four active torque producing areas all with the same polarity
• 30% reduced use of copper in the coil
• Maximum torque production from all magnetic field interactions
• Reduced motor size due to patented unique design requires no unproductive open spaces
• Large Lorentz Force that peaks with a large reluctance force. Best way to explain this is to quote their website: " by extending the length of the magnetic tunnel region, the torque that is present throughout the coils travels without regard to the coils at pole face length. Unlike existing conventional machines where torque is only present at an optimum point as it approaches a magnetic pole, the HET has no single optimum point but rather all positions exhibit maximum torque. The torque and force will exist while the coil in in the tunnel, regardless of tunnel length.

Traditional electric motors have always had a current pulse from the three phase supply requiring a timed rotation that allows for optimum torque production at a single instant in time where only a single phase is active. Electronics have been used to manipulate and soften the pulsations to some degree to gain performance as seen by the current leading EV manufacturers.

The HET motor is able to use a different approach due to the large force presented. One could talk about coils, poles and phases but the end result is that the the technology used by the HET Motor allows for all phases produced to create a continuous pulse of power. These power pulses overlap rather than being sequential thus eliminating torque pulsations ending with maximum torque production.

The HET Motor has an advantage that no other electric motor can equal and that is that via software control, the phases can be controlled into particular patterns allowing for true variable pole count ending in adjustable speed / torque development. To quote Linear Labs: "This allows a speed change increase with no changes in frequency, current or voltage level, which makes an electronic transmission possible."

Current electric motors use what is called Field Weakening. This is where one has peak torque at 0 RPM but trades torque for speed as it goes faster. Excitation speed increases as torque drops by weakening the magnetic fields.

Induction motors increase speed by reducing this excitation current, permanent magnet motors inject an opposing current to control this which is known as a D axis current injection. The constant horsepower region is what this area of speed increase is called. Torque being traded for speed, but total horsepower does not change.

Efficiency drops off in the uses as stated above and this is what the HET motor addresses with its revolutionary design. To quote Linear Labs: " By slightly rotating a single side rotor, an axial magnetic component is introduced. This weakens , as far as the coils are concerned, the total magnetic field experienced by the coils. The degree of field weakening controls the trade-off between torque and speed.

For the first time in electric machine history, as the HET Motor enters the Constant Horsepower Region, core losses drop and overall efficiencies actually climb."

At this time you would not be blamed for saying "SO WHAT" what does this get me?

The benefits of this revolutionary new motor or as Linear Labs likes to call it their electric turbine is the following list:

• Magnetic Configuration producing 100% more torque than any other design.
• Efficiency, reduced copper losses resulting in reduced on-board energy storage.
• Power, testing has shown that the HET motor with standard cooling produces continuous and peak power at 1.9 kW and  2.7 kW at a base speed of 3000 RPM superseding any other commercially available electric propulsion unit.
• Cost and Compactness, resulting in less cost of on-board electronics, converters, controllers, etc.
• Thermal Management, superior design due to less copper and what is known as end windings that contribute nothing to torque or output giving you superior efficiency.
• Variable speed applications, perfect for low speed constant use but also for high speed applications.
• Acoustic Noise, HET motors being smaller than current commercial counterparts along with limited torque pulsation provides a quiet drive system removing most noise heard by the human ear.

Some of the markets that are ripe for Linear Labs motors are of course the auto industry, HVAC industry, industry manufacturing, pretty much any market where constant and variable electric motors are being used. This results in potential energy conservation on a large scale.

Linear Labs see's the potential benefits from scooters, to drones, motorcycles, cars and trucks. The uses of their HET Motor will revolutionize the world while contributing to energy conservation.

 

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