Stator Technology Offers Weight and Efficiency Savings
Article written by Wendy Laursen, a maritime journalist, originally published June 9th, 2021 on The Motorship.
In a second retrofit project on the same vessel, ECM’s PCB stator design technology has proven its value in reducing motor weight and size and has enabled the replacement of an air handler’s belt drive for a higher efficiency direct drive.
Converting an air handler's belt drive to a direct drive configuration increased motor efficiency to 93%.
The first retrofit on the US Maritime Administration training vessel TS Kennedy confirmed the technology’s ability to reduce onboard weight and increase motor efficiency by replacing a conventional motor with a printed circuit board (PCB) stator motor in the vessel’s HVAC system.
Historically, stators tend to be the bulkiest component of a motor or generator, as they are comprised of layered copper windings and iron laminations. Instead, ECM has developed a new stator design by embedding copper-etched conductors into a multilayered PCB. This allows for the creation of very thin, compact, lightweight motors without compromising torque.
The second retrofit project on Kennedy, involving three other air handling motors onboard, took the benefits a step further by increasing motor efficiency as before but this time also using the space savings to convert to a direct drive configuration that replaced the air handler’s existing belt drive. The stator upgrade led to a 66% reduction in volume for the air handler, and the direct drive configuration increased motor efficiency to 93%.
ECM’s cloud-based CAD/CAM software platform PrintStator is able to increase motor efficiency by designing optimum copper geometries that reduce resistance and eddy current losses. Rather than having a uniform copper wire used throughout the windings, ECM varies the shape and thickness of the copper traces to achieve motor efficiencies of over 90%. With no steel in the stator, cogging is also eliminated.
PrintStator ensures appropriate heat management by identifying unused space and shaping the copper that does not carry current so that it conducts heat to the outside edge of the stator where it dissipates. These “heat pipes” also bring heat from the centre of the board to the top and bottom layers.
Many systems involve off-the-shelf motors that may be the best fit but are not the exact fit for the application. Often an oversized motor is used which is not running at peak efficiency, says Rob Luchars, Vice President, Business Development. PrintStator produces a design that is matched to the specific application and operating conditions. “It’s one thing to upgrade your existing motor; that can increase efficiency by around 5%, but you can upgrade system efficiency by around 10% by using the right motor,” says Luchars.
The carbon footprint of the machines is reduced because ECM’s technology enables very thin lightweight motors that require up to 70% less raw materials than traditionally wound machines. For example, a 2.2kW induction motor uses 5kg of copper and weighs 45kg. With ECM’s PCB stator only uses 600g of copper and weighs 12kg. Additionally, permanent magnets can be recycled. If properly cared for, they only lose about 1% of their magnetism every 100 years, so at the end of the motor’s life, they can be re-used in another.
For shipowners looking to meet IMO targets for energy efficiency, the PCB stators brings the ability to retrofit existing motors to boost fuel efficiency. For new buildings, shipowners can challenge shipyards to install high efficiency motors rather than sub-optimal off-the-shelf solutions, says Luchars.
ECM is already installing PCB stator technology into HVAC and generator motor systems onboard commercial and government vessels. The reduction in acoustic and electromagnetic noise that results in very quiet operation is particularly attractive for military applications, and PCB is working with around 40% of the world’s biggest military contractors.
ECM is already installing PCB Stator Technology into HVAC and generator systems onboard commercial and government vessels.
PrintStator facilitates the use of axial flux, air gap permanent magnet motors in new applications. ECM has designed annular motors for fan applications where the propeller blades are integrated in the motor centre to optimize airflow. Stacked or segmented motors are also possible – opening up a nearly infinite number of motor designs, says Luchars.
The company does not manufacture motors in bulk, rather it offers design and prototyping services, enabling equipment designers that would otherwise have bought off-the-shelf motors for their products to manufacture motor that are an exact fit for their application.
According to the International Energy Agency, electric motor driven systems account for over 40% of global electricity consumption. The US Department of Energy estimates the average efficiency of these motors to be approximately 75%. Therefore 10% of global electricity consumption is wasted due to inefficient motor systems. ECM is working in a range of industries to change that situation.