Selecting Electric Motors: Best Fit vs. Perfect Fit
Electric machines are indispensable. They are key to the technologies that keep our air clean, our food and medicines fresh, and our homes and offices comfortable. Electric vehicles are increasingly moving people and cargo, in the air, at sea, and on land. Purpose-built electric machines are redefining what is possible, creating tomorrow’s reality with self-driving cars, robotic surgical tools, autonomous vehicles, and advanced sensors.
As the use electric machines grows, so does the impact of their energy efficiency. In a world striving towards carbon neutrality, electric machines account for over 50% of global electricity use, having the largest environmental impact of any single technology. It is evident that optimized, high performance electric motors can significantly reduce our global footprint. However, until recently, designing a custom motor has been a slow, difficult, and expensive process.
Selecting an Electric Machine
For decades, product designers and innovators have been faced with the same limitations when selecting a motor or generator for their system. Whether improving an existing system or creating an entirely new technology, engineers must either pick from a catalog of finite existing machines or design a custom solution from scratch. Each has its challenges.
An ECM employee holds a conventional copper wound stator (on the right) and an ECM PCB Stator (on the left) for comparison of 3HP machines.
Picking a motor from a catalog of fixed frame sizes, speeds, and torques often results in an imperfect match which limits a system’s potential. The best-fit, off-the-shelf motor is commonly over-sized, inefficient, and ignores application specifics such as thermal conditions.
Alternatively, one can design a custom purpose-built machine, but this is often a long and labor-intensive process. These custom solutions can also be heavily limited by conventional motor technology and the transition from prototyping to full-scale production further limits the viability of these products. For example, new motor designs that involve copper wound stators often require unique assembly processes and machinery when scaling to production. As a result of these cost and time factors, most product designers resort to off-the-shelf machines.
A New Way to Design Motors
An extremely flexible, optimized, software-based motor could rapidly transform how innovators select and design machines. E-Circuit Motors (ECM) is a Massachusetts-based startup dedicated to this idea. ECM aims to provide the next generation of designers and engineers with a motor design platform which takes full advantage of their innovations and modern manufacturing. To make this vision a reality, ECM created PrintStator, a revolutionary design-to-manufacture software platform that enables an infinite range of design possibilities.
The platform is anchored to ECM’s proprietary Printed Circuit Board Stator design. By replacing the copper windings used in many conventional motors with a printed circuit board which works in conjunction with permanent magnets, ECM has developed a unique axial flux motor design. PCB Stators are extremely thin and require significantly less copper than other machine types. As a result, ECM’s machines are up to 70% lighter and use up to 80% less raw material than readily available off-the-shelf alternatives.
ECM’s Patented Stator replaces the copper wiring in conventional motor technologies with a Printed Circuit Board.
Further, the lack of iron in ECM’s stator results in no preferred rotor positions or cogging. This enables ECM motors to provide a superior quality of motion and produce little vibration or noise. In some noise critical applications, ECM customers have reported a 20dB – 30dB noise reduction. Motors with PCB Stators have also been observed to have very little EMI, an important characteristic for applications in close proximity to sensors.
Motor as a Software
Certainly, the most important aspect of ECM’s motor platform is not a single high performing motor design or characteristic of PCB Stators, but instead, the infinite range of design possibilities. With ECM’s software, a user can generate a unique ECM motor by simply providing machine requirements. From a discrete set of motor characteristics, including torque and speed, the software produces an optimized PCB Stator motor design with exact operating conditions. With PrintStator, designs are ready in a matter of hours and functioning custom prototypes are just a few weeks away.
ECM’s design software offers an unmatched flexibility, time-to-market, and scalability.
Since PrintStator based motors are co-designed with their operating points, they offer remarkable system-level efficiency improvements. Within a broad range of applicability, a motor designed and developed with ECM’s platform will almost always be lighter, smaller, and more efficient in an application than an off-the-shelf motor.
PrintStator has designed PCB Stators for machines the size of a U.S. Quarter.
Streamlining the manufacture of PCB stators is another challenge that ECM has addressed with its platform. The output of PrintStator includes a package of Gerber files that can be sent out and understood by existing printed circuit board houses for immediate manufacture of the stator. The physical dimensions of the PCB stator are also feed into a parametric design process which models ancillary components, such as the housing, and rotors. These enter a CAD/CAM process and can be made in parallel with the stator.
With ECM’s platform, design to prototyping to scaled production of PCB stators is an efficient process, requiring little manpower and utilizing existing manufacturing techniques and machinery. The scalability and delivery of these custom motors leverages the global capacity of the established printed-circuit board industry. The end result is unmatched flexibility, time-to-market, and scalability.
How does it work?
PrintStator uses patented optimization algorithms to design application-specific motors quickly and efficiently. With the software, numerous design iterations can be investigated with no wasted effort. The software can explore a nearly infinite number of design priorities, including size, weight, efficiency, cost, etc, and then re-prioritize without starting over. For example, when a “maximum efficiency motor” that fits in a given space is developed, it may motivate solving for the “minimum material” motor with efficiency above a particular value.
PrintStator enables a nearly infinite number of PCB Stator design possibilities.
The software also embeds a fleet of patented design features into each stator design, further increasing design potential. Thermal regulation features and specialized winding patterns are examples which ensure superior performance and an optimized use of raw materials.
With the software, designs can also be created utilizing existing components or specific magnets. Further, the trade-off of using these existing parts is easily investigated. With this idea in mind, ECM has used PrintStator to design a limited number of rotors, magnets, and stators to cover the requirements of an entire line of motors.
The shape and form factor of ECM motors is also flexible. ECM motors can be designed as annular rings, segments, and stacked machines. PrintStator has been used to wrap motors around torque multipliers, fit motors into sports equipment, integrate motors with spheres, toroids, ducts and pipes, optimize the performance of motors operating in viscous fluids, and to optimize system performance when combined with fans and pumps.
Who has it worked for?
ECM has active projects with approximately 1/3 of major aerospace and defense contractors. Leading companies in HVAC, robotics, unmanned vehicles, precision motion control, pointing applications, haptic systems, physical therapy, and medical devices are prototyping ECM machines and using ECM’s technology. These projects cover machines from zero to 10kW, low speed torque motors to 30,000rpm.
Innovators around the world are discovering the value of PCB stator technology for their products. Start-ups, universities, government entities and industry giants are all using PrintStator to design remarkable machines. ECM’s extreme design flexibility, time-to-market, and scalability makes the technology valuable for almost any application.
ECM is currently working with partners in a wide range of industries, prototyping custom PCB Stator solutions and assisting with vertical integration.
How does it work for you?
In the next twelve to eighteen months, ECM aims to release PrintStator, allowing engineers to interact directly with the software platform to create their own integrated, specialized motors and generators – specific to their end-use applications – and leverage printed circuit board design houses and other ECM approved vendors to deliver a complete solution within weeks.
Currently, ECM’s software and its complete design flexibility is offered to its partners through a software-as-a-service model in which ECM’s business development unit collects motor specifications and presents design results in the form of parametric models and predictive datasheets. Partners can then iterate on designs with ECM’s expert assistance and ultimately order prototypes of their application’s custom solution from ECM.
Since ECM’s product is data, copies can be re-made globally at any time and ECM is not a part of their partner’s supply chain. The ECM platform aims to assist partners with their own scaled production and vertical integration of PCB Stator machines.
ECM’s motor, as software, reduces supply chain risks stemming from location and market, leverages the power of the market to reduce costs, scales production by leveraging an existing and highly evolved industry, and ultimately provides a designer with exactly the right motor or generator. In a rapidly changing world, ECM’s PrintStator offers the flexibility needed for a generation of electromechanical and mechatronic products that we have not yet imagined.