Multi-Cage Rotor Layout for Harmonic-Balanced Induction Motors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing asynchronous electric motors with squirrel-cage rotors face manufacturing complexities and inefficiencies due to difficulties in automating insertion windings and harmonics caused by dental windings, leading to high manufacturing costs and electrical imbalances.
Innovation Solution
A rotor design featuring multiple squirrel cages with conductive bars and short-circuit rings, where all conductive bars are equidistant from the central axis, allowing for identical electrical and magnetic behavior, and using a dental winding stator to simplify manufacturing and reduce harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If insertion winding is used for the stator, then the motor can be manufactured, but the manufacturing process becomes difficult to automate and costs increase
Solution Approach 1:
The invention divides the rotor into multiple independent squirrel cages (at least two cages) with conductor bars arranged at identical distances from the central axis. This segmentation allows each cage to be manufactured and positioned independently, facilitating automated assembly processes while maintaining electrical balance and reducing harmonics.
Solution Approach 2:
The invention uses asymmetrical positioning of conductor bars within the multi-cage structure, where bars in different cages are angularly offset from each other. This asymmetrical arrangement balances the overall rotor configuration, reducing electrical imbalances and harmonics while enabling standardized manufacturing components.
2Ease of manufacture
If dental winding is used for the stator, then manufacturing cost is reduced, but harmonics are produced that slow down rotor rotation and efficiency decreases
Solution Approach 1:
The invention converts the harmful effect of harmonics generated by dental winding into a beneficial outcome by using multiple squirrel cages with specific angular offsets. The harmonic currents induced in the multi-cage structure are balanced and counteracted, transforming the potential energy loss into improved motor performance while maintaining the cost advantages of dental winding.
Solution Approach 2:
The invention changes the electrical parameters of the rotor by introducing multiple cages with specific conductor bar arrangements and angular offsets. This parameter modification alters the rotor's response to harmonic currents, reducing their detrimental effects and improving overall motor efficiency while maintaining compatibility with cost-effective dental winding stators.
3Ease of manufacture
If multi-cage rotor is used with non-symmetrical cages, then manufacturing is simplified, but electrical imbalances and magnetic imbalances occur
Solution Approach 1:
The invention deliberately uses asymmetrical angular offsets between conductor bars in different squirrel cages to achieve overall symmetry in the rotor's electrical characteristics. Each cage can be manufactured with simple, identical components, but their angular arrangement creates balanced electrical and magnetic fields, eliminating imbalances while maintaining manufacturing simplicity.
Solution Approach 2:
The invention applies different angular positions (local quality) to conductor bars in different cages while maintaining identical bar designs and dimensions. This local variation in positioning compensates for the simplicity of standardized cage manufacturing, ensuring electrical balance and magnetic symmetry without increasing manufacturing complexity.
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 design simplifies rotor manufacturing, reduces harmonics, and improves motor efficiency by ensuring identical torque and balanced magnetic behavior, leading to a more cost-effective and efficient electric motor.
Implementation Method 1
a stator (not shown), the rotor and the stator being positioned coaxially around a central axis of the rotor
Implementation Method 2
The rotor is driven in rotation by the stator
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A rotor for an electric motor comprises a rotor shaft, at least two interlocking squirrel cages, and a lamination stack (211). Each squirrel cage includes at least two conductive bars and at least two short-circuit rings connecting the conductive bars. All conductive bars in all squirrel cages are equidistant from a central axis (X200) of the rotor. Each end (211B, 211C) of the lamination stack (211) comprises a stack of laminations alternating between insulating laminations (210b) and short-circuit laminations (210c), arranged in the same order along the central axis, and as many short-circuit lamination groups as the rotor has squirrel cages. Two adjacent short-circuit lamination groups are angularly offset by an angle equal to an angle (α) of the squirrel cage offset. The short-circuit plates include lights (226) housing the short-circuit rings.