Synchronous Motor Rotor with Nested Magnets and Pole Gap Bars
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Solution Overview
Problem
Existing synchronous motors face challenges in starting independently on a three-phase supply network and experience torque fluctuations during startup and deceleration.
Innovation Solution
A synchronous motor design featuring a rotor with a laminated core and embedded permanent magnets, where the magnets are positioned close to the rotor shaft, and a squirrel-cage structure with pole gap bars, allowing for efficient torque transmission and reduced fluctuations, enabling self-starting without additional power electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If magnets are positioned close to the rotor shaft to reduce torque fluctuations, then torque stability improves, but the remaining wall thickness of the laminated core becomes insufficient for torque transmission
Solution Approach 1:
The magnets are nested within recesses in the laminated core, with the laminated core itself nested around the rotor shaft. This nested structure allows the magnets to be positioned close to the shaft while maintaining sufficient wall thickness through the recess design, resolving the contradiction between torque stability and torque transmission capability.
Solution Approach 2:
The laminated core features locally varied thickness through strategically designed recesses that accommodate magnets. The wall thickness is optimized locally - thinner where magnets are positioned for stability, and sufficient where torque transmission is critical, thus resolving the contradiction between local torque stability and overall torque transmission.
2Stability of the object's composition
If a laminated core with recesses for magnets is used to enable close magnet positioning, then manufacturing complexity increases, but torque fluctuation reduction is achieved
Solution Approach 1:
The laminated core is segmented into multiple laminations with recesses designed to accommodate magnets. This segmentation allows the complex structure to be manufactured as separate layers that are then assembled, reducing the overall manufacturing complexity while achieving the desired magnet positioning for torque stability.
3Reliability
If pole gap bars extending deeper in the radial direction are used for pole separation, then pole separation effectiveness improves, but the remaining wall thickness for torque transmission decreases
Solution Approach 1:
The pole gap bars extend deeper in the radial direction only in specific circumferential regions where pole separation is needed, while maintaining sufficient wall thickness in other regions for torque transmission. This localized variation resolves the contradiction between pole separation effectiveness and overall torque transmission capability.
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 motor achieves reduced torque fluctuations and efficient energy use by utilizing a laminated core and squirrel-cage structure, allowing for direct and indirect torque transmission, and enabling cost-effective and easy manufacturing.
Implementation Method 1
the starting is essentially effected by the short-circuit cage according to the asynchronous principle
Implementation Method 2
after starting, essentially a synchronous working principle is effective
Implementation Method 3
Magnets are provided in the laminated core, which are arranged substantially directly on the outer circumference of the rotor shaft
Data Source
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AI summary
Disclosed is an electric motor, the rotor shaft of which is connected to a core stack, especially in a rotationally fixed manner, particularly for transmitting torque. Said electric motor comprises a cage winding that is provided with bars which are disposed especially at regular intervals in the circumferential direction. Some of the bars are designed as interpolar bars which run lower in a radial direction than the other bars. The radially internal end regions of the interpolar bars are arranged between magnets in the circumferential direction.