Traction Motor Rotor Structure With Drum-Held Laminated Core
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Solution Overview
Problem
The manufacturing of Permanent Synchronous Machines (PSM) with buried magnets and drums is complex due to numerous tolerances, leading to inefficiencies and increased scattering losses, while machines with surface magnets offer higher mechanical output but at the cost of lower efficiency and poorer acoustic behavior.
Innovation Solution
A rotor device for an electric machine featuring a rotor laminated core with embedded magnetic units and thin fixation bars, where the magnetic units are held together by a drum, eliminating the need for additional bars and simplifying manufacturing, while reducing scattering losses and enhancing concentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bars are used to reinforce the laminated core around flux barriers, then mechanical strength is improved, but scattering losses increase
Solution Approach 1:
The invention extracts and removes the bars from the rotor structure by replacing them with a drum. The drum radially encloses the rotor laminated core and mechanically holds together the inner sheet metal element, intermediate sheet metal element, and outer sheet metal element without requiring additional bars in the area of the flux barriers, thereby eliminating the scattering losses associated with bars while maintaining mechanical strength.
2Manufacturing precision
If multiple components with tight tolerances are used, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The invention merges multiple components into a more integrated structure. The drum radially encloses the rotor laminated core and simultaneously performs multiple functions: it provides mechanical strength, holds together the sheet metal elements, and eliminates the need for separate bars. This integration simplifies manufacturing by reducing the number of parts and assembly steps while maintaining the necessary precision.
3Power
If surface magnets are used instead of buried magnets, then mechanical output is improved, but efficiency and acoustic behavior worsen
Solution Approach 1:
The invention employs a nested structure with inner magnetic units positioned between the inner sheet metal element and intermediate sheet metal element, and outer magnetic units positioned between the intermediate sheet metal element and outer sheet metal element. This nested arrangement of magnetic units within the laminated core structure enables the machine to achieve both high mechanical output and high efficiency by optimizing the magnetic flux distribution and reducing losses.
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 manufacturing, reduces scattering losses, and improves the rotor's mechanical strength and efficiency, making it suitable for serial production and increasing power density and maximum speed.
Implementation Method 1
In order to keep the laminated core securely together even at high speeds (centrifugal force), such drums are usually made of metal or fiber-reinforced plastic.
Implementation Method 2
In permanently energized synchronous machines (PSM), the generation of the magnetic field in the rotor is performed using a system consisting of one or more magnets. The magnetic flux of the rotor is usually constant.
Implementation Method 3
In order to keep the torque ripple of the machine as low as possible during operation, flux barriers are regularly used. For this purpose, the rotor laminated core is equipped with magnetically non-conductive or poorly conductive cavities, which extend along the buried magnets.
Implementation Method 4
A rotor device of an electric machine, in particular for a traction drive of a motor vehicle
Data Source
AI summary
A rotor device, including a rotor having at least one rotor laminated core and drum radially enclosing the rotor. Magnetic units including inner and outer magnetic units are embedded in the rotor laminated core. The inner magnetic units are each arranged between at least one inner and intermediate sheet metal element. The outer magnetic units are each arranged between at least one intermediate and outer sheet metal element. Flux barriers extend along the magnetic units. At least one inner, intermediate, and outer sheet metal element are mechanically held together by the at least one drum. The at least one intermediate sheet metal element is fixed to the at least one inner sheet metal element by fixation bars in an area of the flux barriers. Each of the at least one outer sheet metal elements are fixed to the at least one intermediate sheet metal element by the fixation bars.