Rotor with Reduced Radius for Dual-Mode Motor
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Solution Overview
Problem
Existing rotor designs for electric motors are complex and costly to produce, and they often require specialized construction for specific operating modes, which is inefficient given current energy efficiency requirements.
Innovation Solution
A rotor design where the radius is reduced between short-circuit rings to accommodate squirrel cage bars and permanent magnets, allowing for the modification of a commercially available squirrel-cage rotor to support both asynchronous and synchronous operations, enabling the production of two motor types economically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotor is designed with separate synchronous and asynchronous rotor areas, then both operating modes are supported, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The rotor design enables a single rotor structure to perform both synchronous and asynchronous functions. The squirrel cage winding provides asynchronous starting capability, while the permanent magnets enable synchronous operation, eliminating the need for separate rotor constructions for different operating modes.
Solution Approach 2:
The invention combines the squirrel cage winding and permanent magnets into a single integrated rotor structure. The permanent magnets are positioned in the radial outer area while the squirrel cage occupies the radial inner area, creating a unified rotor that supports both operating modes simultaneously rather than requiring separate rotor areas.
2Ease of manufacture
If permanent magnets are applied to a standard squirrel-cage rotor without radius reduction, then there is insufficient space for magnets, but reducing the radius decreases the radial height available for cage bars
Solution Approach 1:
The rotor grooves are designed with different shapes in different radial areas. The radial inner area features teardrop-shaped grooves optimized for squirrel cage bars, while the radial outer area has slot-shaped grooves designed for permanent magnets. This local differentiation allows each component to be optimally positioned without compromising the other.
Solution Approach 2:
The rotor grooves are pre-formed during the casting process with the appropriate shapes for both cage bars and permanent magnets. This preliminary action ensures that when the radius is reduced, both components can be properly accommodated without requiring additional complex manufacturing steps.
3Volume of moving object
If the rotor radius is reduced to accommodate permanent magnets, then magnet installation space is created, but the air gap between stator and rotor increases
Solution Approach 1:
Instead of reducing the rotor radius uniformly, the invention positions permanent magnets in the radial outer area of the rotor, utilizing the radial dimension strategically. The radius reduction is localized to create magnet space while maintaining the overall rotor outer diameter, thereby minimizing the impact on the air gap width.
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 simplifies the production process, reduces costs, and allows for efficient operation by enabling the creation of both asynchronous and synchronous motor types from a single rotor variant, with the use of rare earth magnets providing high stability and reduced torque ripple.
Implementation Method 1
permanent magnets applied to the rotor in the radial outer area of the rotor, in particular corresponding to the cage bars
Implementation Method 2
the rotor (11) is reduced in radius... so that permanent magnets (19) can be attached to the rotor (11)
Implementation Method 3
squirrel cage with in the Rotor grooves inset, preferably cast, cage bars (15) and the cage bars on both end faces of the laminated core connecting short-circuit rings (17)
Implementation Method 4
cage bars (15) and the cage bars on both end faces of the laminated core connecting short-circuit rings (17)
Implementation Method 5
gluing the magnets in place serves as a means of galvanic isolation due to the resulting adhesive film between the magnets and the laminated rotor core with cage bars
Data Source
AI summary
The invention relates to a rotor having a short circuit cage and permanent magnets distributed about the circumference, wherein the rotor comprises a core stack extending over the entire rotor region, having longitudinally continuous rotor slots, wherein the short circuit cage draws the rotor slots over the entire length of the core stack, wherein the short circuit cage is designed having cage bars laying in the rotor slots, preferably cast therein, and short circuit rings connecting the cage bars at both end faces of the core stack, wherein the radius of a rotor region is reduced by at least the radial thickness of the permanent magnets. The radius of the rotor (11) is reduced over the entire length between the short circuit rings (17), such that the radial height of the cage bars (15, 29) or cage webs (27) connected thereto is reduced. Permanent magnets (19) are mounted on the rotor (11). The invention further relates to an electric motor having such a rotor, and to a radial pump having such an electric motor. The invention further relates to a method for operating an electric motor having such a rotor, and to a method for producing such a rotor and/or electric motor.