Induction Motor Rotor With Varying Slot Widths
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Solution Overview
Problem
Existing induction motor rotors face challenges in achieving balanced slot spaces and maintaining constant magnetic flux density due to fixed rotor tooth widths, which limits their performance under magnetic saturation conditions.
Innovation Solution
The design features a rotor core with slots of varying widths, including T-shaped and double squirrel-cage configurations, where the width between adjacent slots is narrower on the outer peripheral side than the inner side, and the inclusion of leakage slots to manage magnetic flux and reduce secondary resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotor tooth width is fixed to maintain constant magnetic flux density, then the magnetic flux distribution is uniform, but the slot spaces cannot be extended and motor performance is limited
Solution Approach 1:
The patent applies local quality by making the rotor tooth width vary in the circumferential direction - narrower at the outer peripheral side and wider at the inner peripheral side. This allows different regions of the rotor to have different properties: the outer region concentrates magnetic saturation for high starting torque, while the inner region maintains adequate flux density for running efficiency, thereby extending slot spaces and improving overall motor performance without maintaining uniform tooth width
2Productivity
If the slot width is increased to extend slot spaces, then more conductor material can be accommodated, but the rotor tooth width must be reduced which causes magnetic saturation and reduces efficiency
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through circumferential variation of rotor tooth width. The narrower outer rotor teeth concentrate magnetic saturation in the high-torque region where it is most beneficial, while the wider inner rotor teeth maintain adequate magnetic flux density in the running region. This allows slot spaces to be extended with larger conductor material without causing excessive energy loss, as the magnetic saturation is localized to where it provides performance benefit
3Productivity
If the rotor tooth width is reduced to accommodate larger slots, then slot spaces are extended for better conductor placement, but the magnetic flux density becomes non-uniform and motor efficiency decreases
Solution Approach 1:
The patent applies local quality by intentionally creating non-uniform rotor tooth width distribution - narrower at the outer periphery and wider at the inner periphery. This deliberate non-uniformity allows larger slot spaces for improved conductor placement while maintaining appropriate magnetic flux density in each region. The outer narrow teeth concentrate flux for high starting torque, while inner wide teeth maintain flux uniformity for running efficiency, thus improving conductor placement without sacrificing overall motor 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 motor performance by concentrating magnetic saturation on specific parts of the rotor teeth, reducing magnetic permeability and improving efficiency by effectively utilizing magnetic flux and reducing secondary resistance.
Implementation Method 1
concentrating portions of rotor teeth under magnetic flux saturation
Implementation Method 2
squirrel-cage secondary conductor having a nonmagnetic and conductive material filled in each of the slots
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To provide an indication motor rotor capable of improving motor performance by concentrating portions under magnetic saturation conditions of rotor teeth. The rotor 1 of an induction motor of this invention may include slots 3 formed approximately in the shape of a T. The slots 3 may be formed so that top slots 3a are arranged on an outer peripheral portion of a rotor core 1a, and bottom slots 3b are arranged on an inner side of the top slots 3a. The width in the circumferential direction of the top slot 3a is wider than the width in the circumferential direction of the bottom slot 3b, and the width in the circumferential direction of a rotor tooth 4 between adjacent top slots 3a is narrower than the width in the circumferential direction of the rotor tooth 4 between adjacent bottom slots 3b.