Air Core Motor-Generator Weight Reduction
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Solution Overview
Problem
Current electric machines that achieve higher efficiency often require costly magnet materials and complex manufacturing, making them unfeasible for widespread adoption due to high costs and material usage.
Innovation Solution
The development of an air core motor-generator with a unique construction that utilizes pre-bundled insulated conductor strands and a stator backiron made from thinner silicon steel or powdered ferromagnetic materials, such as Sendust, to reduce material usage and manufacturing costs while maintaining high efficiency, featuring a high magnetic pole count and a larger magnetic airgap to minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional electric machines use traditional construction methods, then manufacturing costs and material usage are high, but efficiency is limited
Solution Approach 1:
The stator backiron is divided into multiple arc segments that are assembled together to form the complete stator structure. This segmentation allows for reduced material thickness while maintaining structural integrity and magnetic flux conduction paths, directly addressing the contradiction between efficiency and material usage.
Solution Approach 2:
The patent employs thinner stator backiron (reduced thickness parameter) and operates at higher magnetic pole counts (increased pole parameter), which fundamentally changes the magnetic flux distribution and reduces the required material quantity while improving power conversion efficiency through reduced magnetic path length and losses.
2Weight of moving object
If high magnetic pole count is used to reduce backiron thickness and weight, then weight is reduced, but magnetic flux frequency increases causing higher eddy current and hysteresis losses
Solution Approach 1:
The patent accepts higher magnetic flux frequency as an inevitable consequence of high pole count design, but compensates by using thinner backiron sections and optimized material selection to reduce the magnitude of eddy current and hysteresis losses, thereby achieving weight reduction while controlling energy losses.
Solution Approach 2:
The use of powdered ferromagnetic materials or laminated structures in the stator backiron creates a composite construction that reduces eddy current paths and hysteresis losses at high frequencies, enabling the high pole count design to achieve weight reduction without excessive energy losses.
3Ease of manufacture
If air core construction with larger magnetic airgap is used, then manufacturing is simplified and costs are reduced, but magnetic flux conduction path increases
Solution Approach 1:
The patent optimizes the magnetic airgap length as a critical parameter, balancing the need for simplified manufacturing and reduced costs against the requirement for efficient magnetic flux conduction. The airgap is made larger than conventional designs to eliminate complex slot structures, but its dimensions are carefully controlled to minimize excessive magnetic reluctance and flux path length.
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
This design achieves up to an 80% reduction in weight and lower manufacturing costs, with improved thermal conductivity and reduced magnetic losses, enabling higher efficiency and cost-effective power conversion between electrical and mechanical energy.
Implementation Method 1
The rotor comprises permanent magnets that generate magnetic flux across the magnetic armature airgap and through air core armature windings
Implementation Method 2
The stator is stationary adjacent to the rotor and magnetically exerts torque upon the rotor across the magnetic armature airgap in response to applied electric power
Implementation Method 3
The conductor strands are enclosed by a serve that holds the strands together and the serve of the windings is bonded to the armature airgap surface of stator backiron
Data Source
AI summary
An electric machine for converting between electrical and rotary mechanical energy includes a rotor journaled to rotate about an axis of rotation, and a stationary stator mounted adjacent to the rotor. The stator has a ferromagnetic backiron with a surface facing the rotor across a magnetic airgap and having windings applied in a winding pattern formed directly onto the stator backiron and adhered to its surface with a pre-applied tacky adhesive. The windings magnetically exert torque upon the rotor across the magnetic armature airgap in response to electric power applied to the windings. The rotor has permanent magnets that generate magnetic flux across the airgap and through the windings. The windings are comprised of pre-bundled multiple individually insulated conductor strands that are electrically connected in parallel but are electrically insulated from each other along their lengths inside said magnetic armature airgap.