Electric Machine Rotor With Eccentric Apertures
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Solution Overview
Problem
Direct-online synchronous reluctance motors and induction motors face inefficiencies due to harmonic losses and temperature rise caused by variable speed drive harmonics, which are not effectively addressed by existing rotor designs, leading to energy wastage and structural complications.
Innovation Solution
The implementation of a rotor design with an axially sparse stack structure and eccentric shaft holes, which reduces harmonic currents by varying the radial distance of apertures and eliminates bridges at the rim, allowing for improved electromagnetic response and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bridges are added through apertures of stack elements to provide structural support, then structural strength is improved, but power factor losses increase and mask plate structure becomes complicated
Solution Approach 1:
The patent removes bridges from the rotor design entirely, extracting the problematic structural element that caused power factor losses and mask plate complications. The rotor achieves structural integrity through alternative means without requiring bridges through the apertures.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the rotor. The outer rim and stack elements have specific structural properties that provide necessary strength without requiring additional bridges, allowing local optimization of both strength and electromagnetic performance.
2Temperature
If small air-gaps are added between outer rim of rotor and cage structure to prevent harmonics, then temperature reduction is improved, but harmonic losses in cage increase during variable speed operation
Solution Approach 1:
The patent converts the potential harm of harmonic currents into a benefit by designing the rotor structure to guide and control harmonic flux paths. The apertures and stack element configuration transform harmful harmonic losses into useful magnetic flux patterns that support motor operation while reducing temperature.
Solution Approach 2:
The patent changes key geometric parameters of the rotor, including aperture dimensions, stack element thickness, and radial positioning, to optimize the balance between temperature control and harmonic loss reduction. These parameter adjustments allow the rotor to operate efficiently across different speed conditions.
3Ease of manufacture
If conventional rotor design with bridges is used to maintain structural integrity, then manufacturing simplicity is improved, but electromagnetic efficiency decreases due to harmonic losses
Solution Approach 1:
The patent segments the rotor into distinct functional components - stack elements with apertures, outer rim, and cage structure - each optimized for its specific function. This segmentation allows independent optimization of electromagnetic performance while maintaining manufacturability through modular construction.
Solution Approach 2:
Instead of adding structural elements (bridges) to achieve integrity, the patent inverts the approach by using strategic material removal (apertures) and alternative structural arrangements to achieve both electromagnetic efficiency and structural integrity simultaneously.
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 enhances energy efficiency, reduces rotor temperature, and improves power factor by minimizing harmonic flow and leakage flux, while maintaining structural strength and simplifying manufacturing processes.
Implementation Method 1
a plurality of apertures (104) in each of the stack elements (100A to 100L) for providing by the plurality of apertures (104) an electromagnetic response in the rotor
Implementation Method 2
Outer ends (108) of at least two of the apertures (104) of a common channel (300) of the plurality of channels (300) are at different radial distances from the rotational axis (110) of the rotor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A stack of a rotor comprises a plurality of stack elements (100A to 100L) which comprise material of first magnetic conductance. The rotor comprises sectorial sections (102A to 102F) distributed round a rotational axis (110) of the rotor. Each of the stack elements (100A to 100L) has an aperture (104) of second magnetic conductance in each of the sectorial sections (102A to 102F). Outer ends (108) of the apertures (104) are located at a rim (112) of the stack elements (100A to 100L) or at a bridge of the rim (112). The apertures (104) form channels (300) through the stack in a direction of a rotational axis (110) of the rotor. At least two of the apertures (104) of a common channel of the channels have the outer ends (108) at different radial distances from the rotational axis (110) of the rotor.