Alva Industries AS has introduced a novel and versatile production method known as FiberPrinting™, promising to enhance the performance of slotless and ironless machines, motors and generators. Below is a concise overview of this process.
The FiberPrinting™ Process in Three Stages:
- Print: Initially, copper wires and structural fibers are combined into a flat, flexible composite material (Fig. 1). These copper wires form the electrical winding in the final motor or generator.
Fig.1. Drawing1 from Alva’s patent US11646645B2 [1].
- Form: Next, the composite material is shaped into a cylinder and placed inside a mold. A stabilizing filler, typically epoxy, is added.
- Mold: Finally, the material and stabilizer are cured and demolded (Fig. 2). The outcome is a self-supporting cylindrical part with integrated copper winding, generating a rotating magnetic field when powered by AC.
Fig.2. Microscope image of the part of Alva’s slotless stator showing the consolidated litz wire strands, filler material and stator laminations.
Key Advantages:
Higher Copper Fill Factor and Thinner Windings
To minimize copper winding losses, a substantial cross-sectional area of copper conductors is essential to maintain low electrical resistance. Ideally, the area should be filled with copper, achieving a 100% Copper Fill Factor (CFF). However, insulation needs and production imperfections typically reduce this. Lower CFF necessitates larger winding areas, resulting in thicker stator designs, heavier motors, and more expensive permanent magnet materials.
Fig.3. Drawing3 from competing ironless motor manufacturer’s patent US9425664B2[2].
Traditional methods involve winding copper coils around a plastic strip or laminating precision-etched copper sheets with insulating material, both reducing the CFF and taking up valuable space that could be occupied by copper.
Fig.4. Cross-section view of an ironless winding: conventional (left) vs FiberPrinted (right).
Optimal Winding Geometry
Legacy production methods necessitate maintaining an angle on copper windings to wrap around the stator surface, compromising efficiency. FiberPrinting™ allows for completely straight windings, enhancing performance by maximizing the force generated by the coils when interacting with rotor magnets.
Fig.5. Ironless stator by one of the competitors (left) and FiberPrinted stator by Alva (right).
Production Efficiency and Versatility
Alva’s method eliminates the labor-intensive processes associated with stator manufacturing, typically the most complex and costly part of electric motors or generators. Automation of each step enables mass production with minimal manual labor, making FiberPrinting™ one of the first viable solutions for large-scale ironless machine manufacturing.
The process offers flexibility, akin to 3D printing, producing various winding sizes, dimensions, and electrical properties without retooling. Changing the stator component’s axial length, diameter, or electrical properties is as simple as adjusting the composite mat’s production.
A Timely Innovation
Alva’s technology aligns with advancements in power electronics and battery technology, moving towards lighter, more compact, and energy-efficient solutions. This innovation also makes ironless and slotless machines more cost-effective, accelerating the transition to sustainable electric technologies.
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