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‘Revolutionary’ PCB windings halve the size of micromotors

27 October, 2020

A Belgian start-up, Mirmex Motor, has developed a new method for manufacturing high-power-density windings for micromotors that, it claims, will revolutionise traditional winding design and manufacturing methods. The technology, which is the result of seven years of r&d, uses windings formed from flexible printed circuits and is claimed to result in motors that are 50% smaller, 70% more dynamic, with a third of the heat losses of motors that use conventional copper windings, and can be assembled ten times faster.

Work on the new technology started in 2013 at the UCLouvain university in Belgium. In 2017, the team founded Mirmex to continue the work and raised several million euros in funding from local investors and the European Commission. Production has now started with a capacity to produce 100,000 windings per year.

The technology is aimed mainly at slotless permanent magnet motors, either in the form of synchronous or slotless brushless DC (SBLDC) machines. While these motors have existed for 40 years, Mirmex says that they have not seen any significant innovation since their inception, and their coils are complex to design and manufacture.

“The production machines used historically are designed for a particular type of coil or for a single application,” explains the company’s chief technology officer, Dr François Baudart. “This complex process slows down prototyping and manufacturing, making it expensive and inflexible. Since micromotors are mainly intended for areas where innovation and progress are essential, we had to find a better solution.”

Instead of winding copper wires, Mirmex creates and prints windings on strips of flexible PCB (printed circuit board) material, resulting in “never-seen-before" winding topologies. The proprietary patterns are designed using AI (artificial intelligence) algorithms and, once wound, the overlapping layers form motor windings said to be capable of far superior performance than the competition.

Mirmex has developed an automated process for creating the winding topologies and for validating the printing on flexible materials to produce winding patterns that would be impossible to achieve using traditional methods. The PCB coils simplify and speed up motor production, as well as cutting tooling costs. The motors can be customised using software developed in-house.

The new patterns offer possibilities that go beyond the shape of the windings. By varying the size, patterns, thickness and interconnections of the conductors, new capabilities are possible for the micromotors. Mirmex says its software results in the best design for each application and can be adapted to suit a variety of situations.

“This represents a huge leap forward for the micromotor industry,” claims Mirmex Motor’s CEO, Cedric Van Rossum. “Feedback from industry professionals has proven that our solution is well above market standards. We have great ambitions for our micromotors and for our innovative game-changing technology.”

Mirmex's PCB-based technology allows its to produce windings in a variety of configurations that can be tailored to an application

“These days, micromotors are everywhere, from drones to surgical devices and robots,” adds the company’s chief scientific advisor, Professor Bruno Dehez. “The demand for micromotors continues to grow.”

“The performance of such motors depends entirely on their copper coils,” he continues. “Their windings are particularly long and tedious to wind in order to obtain the best possible result. Many coils are still assembled by hand in the prototyping phase.”

Mirmex expects its motors and windings to be used for high-performance applications such as robots, surgical tools, prostheses and aerospace equipment. The company cites several areas where its technology could deliver substantial benefits:

• Industrial applications such as robots need dynamic drive systems. The PCB-based motors allow faster movements and higher productivity than conventional micromotors. Robots driven by the new motors can also be made extremely precise because their flexible windings filter harmonics better.

• Micromotors used in surgical and dental equipment have to be small and light. Traditionally, they have often been undersized, leading to overheating. It costs too much to optimise windings to achieve the ideal performance for every application. Mirmex says its windings can be optimised much more easily, and hat the smaller size and higher power of its motors can decrease instrument cool-down times as well as being among the lightest on the market.

• In power tools, conventional motors cannot reach the required torque in all possible configurations, and often need a gearbox. The new micromotors can increase the torque without needing a gearbox, thus reducing weight and boosting efficiency.

• In prosthetics and other bio-robotic applications, battery lives are a major problem. The new micromotors weigh less, and are compact and efficient. Prosthetic devices therefore need less energy to perform the same action, extending battery lives. The new motors will also help to produce smaller prostheses, such as hands or those for children.

Mirmex plans to licence its technology to other motor manufacturers as well as producing motors itself.

Mirmex will be producing its own micromotors as well as licencing its technology to others

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