Segmented Stator Eddy Current Reduction in Electric Motors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric motors and alternators face efficiency and power density challenges when operating at lower rotational speeds, often requiring gear reduction, which increases complexity, weight, and cost, and can lead to reduced performance and mechanical failures, especially in applications like light electric vehicles where torque density is limited.
Innovation Solution
The design of a transverse flux machine or commutated flux machine with a stator assembly featuring a lamination stack with radially extending beams and gaps to prevent continuous electrical circuits, reducing eddy currents and enhancing magnetic flux path efficiency, allowing for improved torque density and power output in compact forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the number of poles is increased to achieve higher electrical frequency at lower rotational speed, then the electrical frequency and voltage constant per turn are improved, but the winding complexity and coil losses increase
Solution Approach 1:
The stator is divided into multiple independent pole assemblies, each with its own winding. This segmentation allows each pole to be wound separately using simpler techniques, avoiding the complexity of traditional multipole windings while maintaining the benefits of high pole count for increased electrical frequency.
2Use of energy by moving object
If continuous electrical circuits are allowed in the lamination stack, then the magnetic flux path is continuous, but eddy currents are generated causing energy losses
Solution Approach 1:
The lamination stack is segmented into multiple electrically isolated sections using insulating materials placed between laminations. This segmentation breaks the continuous electrical circuit path, preventing eddy current formation while maintaining magnetic flux continuity through the segmented structure.
Solution Approach 2:
Insulating materials are introduced as intermediary elements between the conductive laminations. These intermediaries electrically isolate adjacent laminations to prevent eddy currents while allowing magnetic flux to pass through, thus eliminating harmful effects without compromising magnetic function.
3Speed
If a gear reduction is used to achieve lower rotational speed, then the rotational speed is reduced, but the system efficiency decreases and mechanical failure rate increases
Solution Approach 1:
The electrical parameters of the motor are changed by increasing the pole count, which allows the motor to operate at lower rotational speeds while maintaining the same electrical frequency output. This parameter change eliminates the need for mechanical gear reduction, thereby improving reliability and efficiency.
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 configuration enhances the efficiency and power density of electric machines, reducing inefficiencies and mechanical failures, enabling more compact and powerful motors for applications like e-bikes by minimizing eddy currents and optimizing magnetic flux paths.
Implementation Method 1
The first lamination stack and the second lamination stack are each configured with a plurality of gaps generally radially through the laminae thereof, the gaps in the laminae of each lamination stack defining a plurality of separate circumferential segments in each laminae, to prevent a continuous electrical circuit around the rotational axis from being created
Implementation Method 2
a first lamination stack comprising a first plurality of laminae, the first stack being arranged circumferentially with respect to the rotational axis on a first side of the coil for conducting magnetic flux
Data Source
AI summary
An electrical machine includes a rotor with a rotational axis, a coil arranged circumferentially with respect to and fully encircling the rotational axis, and a stator assembly. The stator assembly includes first and second lamination stacks comprising associated pluralities of laminae, the stacks being arranged circumferentially with respect to the rotational axis on opposing sides of the coil for conducting magnetic flux. The stacks are configured with gaps generally radially through the laminae thereof, defining separate circumferential segments in each laminae, to prevent creating a continuous electrical circuit around the rotational axis in the segments. Each laminae has a connecting ring spaced radially from the segments, and beams connecting the segments to the ring as a unitary piece. Back return elements extend axially between the stacks to provide a flux path therebetween, and are positioned circumferentially between adjacent parts of the beams and radially between the segments and the ring.