After making V8s more efficient, Tula turns its hand to EVs

An iPad is mounted to the dash of a Chevrolet Bolt. Two men are in the front seats, each wearing a face mask.
Enlarge / Riding in Tula’s DMD-equipped Chevrolet Bolt EV.
Roberto Baldwin

SAN JOSE, CALIF.—Electric vehicles are all about small gains in efficiency leading to increased range. Reduce the drag, tweak the acceleration curve, and increase the regenerative braking, and you get a few more miles. Car tech company Tula has come up with another solution to enhance efficiency.

Called Dynamic Motor Drive (DMD), the system pulses the electric motor to operate within a “sweet spot” of efficiency. DMD adds efficiency and removes one of the more controversial materials found in EV motors: rare earth metals. The result is an efficiency gain of about 3 percent. That’s not a huge boost, but if your vehicle gets 300 miles of range, for instance, you get nine extra miles of road you can cover. But the system also sets itself up to work in a world with fewer rare earth magnets.

Those rare earth magnets cost automakers a pretty penny, and they’re not aligned with the green positioning of EVs. Currently, 90 percent of the EV industry’s materials for these magnets (mostly neodymium) come from China. Since late 2021, the price of those materials has increased by about 90 percent. There are plans to increase rare earth mining in the US, but considering the environmental precautions that need to be taken, it still won’t be cheap.

Mining and refining neodymium takes a huge toll on the environment. EVs are supposed to be the greener answer to gas-powered vehicles, so it’s not a good look when mining the magnets that go into an EV can be responsible for introducing toxic chemicals to waterways.

At issue is that a majority of EVs on the road are still using these interior permanent magnet (IPM) motors. Currently, BMW and Nissan have in-production vehicles that use electrically excited synchronous motors (EESM) in their vehicles. Others will likely make the switch at some point in the future. During a presentation, Tula’s senior vice-president of DMD and engineering, John Fuerst, noted that OEMs are largely working toward EESM for their vehicles.

A DMD-enabled electric powertrain running on a test bench.
Enlarge / A DMD-enabled electric powertrain running on a test bench.
Tula

Yet even with their magnet-free motors, neither BMW nor Nissan has created a DMD-capable vehicle. Tula notes that some minor hardware changes have to happen, but most of the DMD secret sauce is in the software that controls the motor.

The biggest issue is figuring out how to force the motor to pulse within the vehicle’s efficiency sweet spot. Each vehicle has a point at which the motor speed and torque are aligned in a way to deliver the best use of energy. As an example, Tula shared a graph showing a point where a vehicle is creating about 75 lb-ft of torque at 3,000 rpm. If the vehicle is traveling at a speed that uses less torque—25 lb-ft, let’s say—the DMD system will pulse the motor 20 times per second while making it produce 75 lb-ft of torque.

Rather than a continuous delivery of power, it’s a pulsed delivery of power. To make sure that doesn’t create a driving experience akin to rolling in a vehicle experiencing a series of tiny earthquakes, Tula has been tweaking the system to reduce that sensation.

Ars got behind the wheel of Tula's DMD test vehicle, this Chevrolet Bolt EV.
Enlarge / Ars got behind the wheel of Tula’s DMD test vehicle, this Chevrolet Bolt EV.
Roberto Baldwin

Tula’s current test vehicle is a Chevy Bolt. When I got behind the wheel, it was difficult to tell if I could feel the pulses from the accelerator and footwell or if I was only imagining them. In other words, unless someone tells you that the DMD system was implemented in the vehicle, you’d be hard-pressed to notice it. Tula is still working on the vehicle to make sure it meets the in-car noise level of a standard Chevy Bolt. Having driven a stock Bolt a few weeks earlier, this in-vehicle noise level seems on par with what I would get from a showroom model.

Tula is currently working on outfitting a BMW i4 with DMD. It’s still early days for that vehicle, and when it comes to in-car noise, the BMW will be a bit tougher than the Bolt.

The company’s goal isn’t to build vehicles for automakers; instead, it wants to send the OEMs the DMD software to implement on their vehicles. Automakers would pay Tula a licensing fee for each vehicle, likely around $50–$70. But it will be a few years before that happens; even in the rosiest predictions, the soonest DMD would be available is late 2025.

Tula is currently installing DMD on a rear-wheel-drive BMW i4.
Enlarge / Tula is currently installing DMD on a rear-wheel-drive BMW i4.
Roberto Baldwin

The goal is to put the system into vehicles for which efficiency and cost are the biggest selling points. There’s very little benefit to adding it to vehicles with two or more motors. On the performance side, a gain of 3 percent won’t impress the future owners of a Porsche Taycan or the Tesla Model S. Instead, this technology, coupled with EESM, will be for those mythical low-cost EVs we keep hoping will come to the US market.

Tula isn’t new to the efficiency game. It created Dynamic Skip Fire, a system that turns off cylinders of large engines to increase a vehicle’s miles-per-gallon rating. GM has implemented the system on multiple vehicles, including the V8-powered Silverado pickup that I drove after testing the specially modified Bolt at Tula’s headquarters. The system delivers a 15 percent efficiency gain and is an improvement over earlier cylinder deactivation technologies that offered less granular control of individual cylinders within an engine.

Tula sees where the industry is headed. EVs are the future, and in order to be part of that evolution, you need to find a way to entice automakers with efficient solutions that work with cheaper motors to produce a smaller environmental impact. If it succeeds, you won’t even know.

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