Axial Flux E-Motor Maker Progresses Toward Mobility, Alters Cooling Design

In 2023, Infinitum maxed out its manufacturing capacity making e-motors for industrial and data-farm customers, putting it on solid footing to add mobility motors to its mix.

Components of Infinitum's axial flux e-motors. After discovering friction losses when spraying the stators with coolant, the jacket handles most of cooling responsibilities for the program. (Infinitum)

SAE Media first introduced readers to Infinitum in last year’s roundup of e-motor developments. (LINK) The company claims it made a 50% smaller and lighter axial-flux motor by replacing all the copper in the stator with printed circuit boards thath have etched copper conductors. The result is higher efficiency due to the elimination of core losses from eddy current, stator hysteresis and more.

Bhavnesh Patel, Infinitum's chief strategy officer, said the company is working with a marine company and a truck manufacturer on mobile applications of their PCB stator motors. (Chris Clonts)

We stopped by Infinitum’s booth at the Consumer Electronics Show in Las Vegas to see how the company has fared recently. Its strategy was to start building industrial motors to meet the world’s biggest e-motor market before moving on to eventually building mobility solutions. We asked Chief Strategy Officer Bhavnesh Patel about that and more.

How is the plan going?

We have maxed out our production capacity on industrial and commercial motors. We’re selling into a lot of data-center cooling applications, as the data centers generate a lot of heat [and are under increasing pressure to be more efficient]. We are also seeing a lot of pump applications and the investment from Rockwell Automation is helping us take this into material handling such as conveyors and luggage handling. And we’re making progress on power take-off applications.

Still working toward mobility, though?

Yes. We have a number of partners that we are working with on a hybrid marine application and a truck application as well. We’ve come a long way in a year.

Mobility suppliers are starting to explore PCB stators as well. Are you concerned they’ll capture that market before you can?

We’re not too concerned on that front. For us, as a startup, we raised $185 million a couple of months ago [the company’s Series E funding]. We must be able to turn that cash into actual progress and milestones.

With the PCB stator, I should also mention that there have been different ways of making this. Our approach is that there are multiple layers on the stator because every layer has a single phase or power -- phase A, phase B, phase C – and layering those on top of each other. Previous approaches that I'm aware of have had those all on a single layer. And so, one of the challenges of that is you have to connect phase A on the first layer to phase A on the second layer to phase A on the third layer. Those interconnections, called vias, are the most unreliable and the most costly. By eliminating or reducing significantly the number of interconnects we have on ours, it makes it a lot more feasible to scale up the technology to make it more commercially viable for various applications.

How does Infinitum combat bearing currents, the stray voltage that can damage bearings and their races?

In our industrial product line, we use hybrid ceramic bearings. That essentially insulates the shaft. The other thing that we've done – and we offer this as an option on our industrial product – is grounding rings. And we have a grounding brush option as well for the inside. Different customers have different preferences.

Since last year, has anything changed with your approach to this kind of e-motor?

In our first approach with the EV motor, we had a hollow shaft and we sprayed the stator directly to cool it. We have a fairly wide air gap between the rotor and the stator. We didn't expect the fluid to create frictional losses. In testing, it did result in some, so we've come up with other ways of reducing or removing that heat. Now we rely more on the cooling jacket, and we’ve also created fins on the inside that move air, which we’re able to push over the stator and get the heat absorbed into the housing.

Are there any other improvements on the horizon?

We're talking to a lot of the automotive companies. One of the concerns with all motors is supply chain risks. Something like 70% of motor magnets come from the same place. So, we've developed an approach that dramatically reduces the amount of rare earth magnets. It’s still an axial flux PCB motor, but we were able to change the way we orient the rotor and the stator. Initial testing has been promising, but we’re not public with the details of that yet.