During a webinar held last October, Fabrizio Bardelli, R&D expert at Came delved into the concepts of co-design, optimization of technical properties, and regulatory compliance of industrial electric motors.
Co-design and optimization
Innovation, customization, and compliance with regulations are three key assets that Came claims to integrate through its consulting-based approach, in order to achieve the best possible electric motor – a goal attainable only through ongoing dialogue with clients. «There is no universal solution: our task is to find, for each requirement, the best balance between performance and cost, evaluating the pros and cons of the various options and collaborating actively with customers.»
Bardelli highlighted two particularly relevant case studies: prototyping of BLDC motors and insulation for inverter-fed stators in accordance with the CEI EN 60034-18-41 standard.
BLDC prototyping
In the design and optimization process, the first phase involves feasibility assessment and stator selection. «The decision-making process is carried out by carefully considering the client’s functional and application specifications: opting for a solid core, ideal for certain configurations, or for a T-segment, which offers a higher filling factor, often comparable to or even better than that of asynchronous stators.» This distinction is strategic for maximizing both the volumetric efficiency and functionality of the winding.
Bardelli explains that, with the mandrel winding technology, managing the wire diameter is crucial, especially in projects requiring large cross-section wires. In such cases, the use of parallel wires is recommended, a solution that facilitates the winding process. Thanks to this technology, it is possible to arrange up to four parallel wires in the same slot, thereby improving conductor material distribution and electrical performance
«When dealing with winding processes – particularly needle winding designed for solid stators – it becomes essential to maintain a clearance of at least 2 mm beyond the wire diameter. This measure allows for smooth and safe insertion of the tool into the stator slot, minimizing the risk of damage or conductor misplacement.»
With regard to process optimization and limits, significant differences are observed among available winding technologies. Needle winding enables the use of a single wire, while parts of the slot remain inaccessible – the so-called ‘forbidden area.’ Conversely, mandrel winding with T-segment makes use of every part of the slot and allows for several wires- up to four – yielding more compact and high-performance windings.
«As for insulation and the development of insulating covers, Came creates highly customized caps, based on client-provided drawings and refining the design to avoid fractures at critical points during production. Both traditional and innovative solutions are offered, including injected types—more costly but widely adopted for large-scale production.»
Another key aspect emphasized by Bardelli is slot insulation management: Came oversees both the design and sourcing of tailor-made insulating materials, ensuring the possibility of implementing dedicated sheets for projects with specific needs.
The sampling and tooling phase is managed with great flexibility: both permanent tools for large-scale industrial production and temporary, low-cost tools for limited series or prototypes can be created. «Once the customized stator is ready, pilot production can be started quickly, coordinating the entire process from laser cutting all the way to testing.» Finally, Came’s consulting does not end with the prototype. The manager explains that the company also supports the customer during subsequent industrialization, implementing automated production solutions that guarantee both repeatability and final quality – essential requirements for those operating in the most competitive sectors of the electromechanical industry.
Optimization of inverter-fed insulation
Regarding issues related to partial discharge, Bardelli recalled that insufficient regulatory compliance can result in disastrous outcomes for the sector: «A non-compliant stator can cause catastrophic failures. In 2024, there were as many as 114 fires in wind turbines, each incurring economic losses of two to three million euros per machine. The cause is often a design that neglects the requirements imposed by partial discharge standards.»
For compliance verification, Came utilizes rigorous methodologies and specific tests: the surge test, carried out with impulses ranging from 1,500 to 4,000 volts, can promptly detect the presence of partial discharge. «This allows us to characterize the stator’s robustness, assigning it a class from A to D and, if necessary, recommending the most appropriate improvements,» Bardelli explained.
As for insulating materials, Came adopts a meticulous and flexible selection process: «We use UL-certified materials for insulation, Grade 2 copper wires and, in more critical environments, Grade 3 wires or the so-called corona-resistant versions. This last option offers superior resistance to partial discharge, although it cannot completely eliminate them.»
Impregnation processes are also carefully tailored to both performance and project cost constraints. «The baseline remains water dipping – an economical but lower-performance solution; for more demanding cases, we turn to polyester resins, which are is more performing but also more costly.»
Special attention is also dedicated to the configuration of windings: «We design windings to minimize phase crossings, accepting an increase in resistance that is offset by improved dielectric strength. The preferred configuration involves a single crossing, which helps mitigate partial discharge risk, though it may affect the motor’s overall efficiency to some extent.»
Finally, Bardelli emphasized the importance of continuous updates: «Only by adopting advanced manufacturing processes, innovative materials, and up-to-date testing tools is it possible to fully satisfy the demands of evolving standards such as CEI EN 60034-18-41, which is currently under revision, with new requirements anticipated by year’s end.»
(by Lara Morandotti)
