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The rotor from an electrically excited synchronous motor manufactured by Schaeffler. (Schaeffler)

Schaeffler promotes e-motor manufacturing flexibility

Supplier said customizable traction-motor approach can optimize projects for preferred outcomes in range, cost and sustainability.

Global auto supplier Schaeffler Group has a message for the EV motor market: the company is capable of building custom solutions for many different EV drivelines and use cases. And it is forthright in saying that not all mobility applications need cutting-edge technology to be effective.

While some e-motor manufacturers have gone to market with a limited number of models – usually employing similar architecture but different levels of output – from which customers can select, Schaeffler insists it will consider building any motor spec brought to it. Daniel Sayre, e-motor business unit director, said the company is dedicated to adapting and working with customers to develop the best solutions for their vehicles.

Sayre said that the company’s global footprint helps it sustainably source materials and consider carbon footprint when deciding where to manufacture an item. “Depending on the type of material in that program, we can select the regions where we get them, to where we process it, and then where we ship from at the end,” he said. The company said its number of potential customers continues to grow. Sayre asserted that requests for proposals to various parts of Schaeffler’s business – from e-motors to full mobility systems -- already number in the hundreds each year.

In a conference call for analysts and media that focused on optimizing designs for range, cost and sustainability, Jonathan Getz, group leader for customer solutions and e-motor research and development, said the company’s array of available technologies allows that. “Optimization allows you to properly balance emerging technologies and find the exact design to match vehicle goals to advanced motor technologies and increase sustainability without sacrificing performance.”

He also said that the company’s local vertical integration presents a cost advantage in addition to offering a single supplier for an entire e-motor solution.

“We have an internal design toolkit that allows for quick tradeoff optimization,” Getz said. “We can tailor the design to minimize raw materials like magnets, as well as carbon dioxide, all while maintaining maximum performance. Then we can take the design and run it through an advanced software that can simulate thousands of designs within minutes. This allows the customer to have no waste in the design while being tuned to the exact project specification.” That equates to reduced risk, he said.

Design, manufacturing options
Schaeffler provided a brief overview of the methods and technologies it can use in traction motors. For example, Getz said the company can use three different lamination technologies when stamping cores: interlocked, backlack (a full-face bonding process resulting in extremely stiff stacks) or single lamination.

With regard to windings, Getz described an array of configurations, including the standard hairpin and axial hairpin versions. But the company also offers continuous-wave winding, which Getz said reduces the number of required welds from 180 to 18 on a motor with 60 stator slots, and a gain of 8 mm (0.3 inches) to 10 mm (0.39 inches) in axial space. The layout, he said, results in more torque from the same space as traditional windings. Also, he said that wave-winding in motors with more than 48 slots delivers a “significant” reduction in NVH.

Getz said that cooling is one of the most-significant areas of variable need, and thus where many motors can be cost-optimized for their use cases. A simple water jacket may be more than sufficient for an auxiliary drive for a low power-density application, he said. But additional cooling frequently is required for high peak- and constant-output vehicles. For these applications, thin spray, novel spray and through-the-lamination cooling are options.

But for ultra high-heat applications, such as vehicles that are performing heavy-duty towing or endure extended high-speed operation, Schaeffler can manufacture motors with Directly Injected Slot Cooling (DISCO) with oil. “This puts the cooling directly in the winding slots,” Getz said. “So, right up against the heat source, allowing the continuous performance to match the peak performance.” He cited a familiar scenario in which vehicles see degraded performance after several sprints or lose some power when trying to pass on the highway. DISCO technology also can result in better harvesting of heat, transferring it more quickly to the battery when it’s beneficial.

Jeremy Vanni, an engineering manager with Schaeffler, addressed a question about motors leaking coolant through the laminations. “It’s completely sealed all the way along the lamination stack” with a very thin thermoplastic.

Getz also said the company’s deep background in manufacturing gives it more data to leverage when it comes to the simulations it can run to help customers choose e-motor components.

He said the company also is working with electrically excited synchronous motors, which are made without rare earth magnets and have traditionally worked better for applications involving continuous runs at a consistent rpm. “It’s not to say ESM motors have not previously existed,” he said. “But ours significantly improves on the efficiency when compared to induction motor technology, while remaining cost competitive to permanent magnet technology. He also said the one-rotor design uses a high copper fill to maximize power density, using recyclable copper. “We’ve tested this specific design at speeds over 18,500 rpm.”

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