PCB Stator Spoke Layout for Lower Resistance Axial Flux Machines
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Solution Overview
Problem
Existing coreless axial flux electrical machines with PCB stators have copper losses dominated by winding resistance, which can be reduced but at the cost of increased complexity and expense due to the number of PCB layers and copper-foil thickness.
Innovation Solution
A stator design for axial flux electrical machines featuring a multi-layered substrate with alternating sequences of circumferentially distributed spokes in two conductive layers, which are electrically insulated and connected in parallel, reducing winding resistance and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the resistance of the winding printed on the PCB is reduced by increasing copper-foil thickness or adding PCB layers, then copper losses are reduced and efficiency is improved, but the cost and complexity of the PCB stator increase
Solution Approach 1:
The stator winding is segmented into multiple discrete conductive spokes arranged circumferentially around the air gap. Each spoke is a separate conductive element that can be independently optimized, allowing the winding to be distributed across multiple PCB layers without requiring excessive copper thickness in any single layer. This segmentation enables efficient current distribution while maintaining manageable PCB complexity.
Solution Approach 2:
The winding design transitions from a planar two-dimensional layout to a three-dimensional distributed structure by arranging conductive spokes in multiple circumferential positions and PCB layers. This dimensional expansion allows the winding to achieve lower effective resistance through parallel current paths without requiring any single copper layer to be excessively thick, thus balancing efficiency with manufacturing feasibility.
2Ease of manufacture
If the area of the PCB is reduced to lower cost, then manufacturing cost decreases, but the winding resistance may increase and efficiency deteriorates
Solution Approach 1:
The conductive spokes are positioned with varying circumferential spacing optimized for local electromagnetic conditions. The spacing and dimensions of individual spokes are tailored to their specific positions around the air gap, allowing efficient use of PCB area while maintaining low winding resistance. This localized optimization enables cost-effective PCB area utilization without compromising electrical performance.
Solution Approach 2:
The design optimizes multiple parameters including spoke width, spacing, circumferential inclination angles, and PCB layer configuration to achieve the lowest possible winding resistance within a constrained PCB area. By systematically adjusting these geometric and electrical parameters, the design achieves efficient current conduction paths that minimize copper losses while keeping the PCB footprint and cost manageable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed stator design reduces copper losses and improves efficiency by minimizing winding resistance while potentially decreasing the cost and size of the electrical machine.
Implementation Method 1
The copper losses are dependent on the resistance of a given winding design. Reducing the resistance of the winding printed on the PCB can offer improved efficiency.
Implementation Method 2
an axial flux electrical machine is provided which includes at least one stator and at least one rotor electromagnetically coupled to the at least one stator
Data Source
AI summary
A PCB stator for an axial flux electrical machine includes at least first and second conductive layers. Each electrical phase winding is formed from an alternating sequence of circumferentially distributed first and second spokes. Each of the first spokes has a radially inner end and a radially outer end and is inclined in a first circumferential direction, and each of the second spokes has a radially inner end and a radially outer end and is inclined in a second circumferential direction opposite the first circumferential direction. The first spokes are disposed in the first conductive layer in M/2 circumferentially distributed groups of N first spokes and the second spokes are disposed in the second conductive layer in M/2 circumferentially distributed groups of N second spokes. The radially outer ends of the first spokes are electrically connected to radially outer ends of the second spokes and radially inner ends of the first spokes are electrically connected to radially inner ends of the second spokes such that the alternating sequence of the first and second spokes spans 360*N physical degrees, N being an integer>=1.