Spoke Rotor Magnet Protrusion Reduces Leakage Flux
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spoked rotors for electrical machines suffer from high leakage fluxes, which reduce power density and efficiency due to magnetic stray fluxes flowing towards the rotor shaft, leading to increased size and weight of permanent magnets and reduced output power.
Innovation Solution
The rotor design features permanent magnets protruding beyond collecting webs made of a paramagnetic material, with optimized magnetic flux distribution, including sectors and fastening rings, to minimize leakage fluxes and enhance power density. The base body is constructed from laminated cores or solid materials, and the magnets are arranged in a spoke-like fashion to direct magnetic flux effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If permanent magnets are arranged in a conventional spoked rotor with collecting webs, then the rotor structure is stable and magnets are retained, but leakage fluxes increase and power density decreases
Solution Approach 1:
The patent inverts the conventional arrangement by having the permanent magnets protrude beyond the collecting webs instead of being fully contained within them. This reversal of the typical configuration changes the magnetic flux path, reducing leakage fluxes towards the rotor shaft and improving power density while maintaining structural stability
2Power
If permanent magnets are made larger to compensate for leakage fluxes, then output power is maintained, but rotor size and weight increase
Solution Approach 1:
The patent changes the geometric parameter of the permanent magnet arrangement by having magnets protrude beyond the collecting webs. This parameter change optimizes the magnetic flux distribution, reducing leakage losses and enabling smaller magnet volumes to achieve the same output power, thereby reducing rotor weight while maintaining power output
3Loss of energy
If collecting webs are made narrower to reduce leakage flux paths, then magnetic flux saturation is improved, but structural strength decreases
Solution Approach 1:
By inverting the arrangement so magnets protrude beyond collecting webs, the patent changes the magnetic flux distribution pattern. This reduces the reliance on narrow collecting webs for flux containment, allowing webs to maintain adequate width for structural strength while still achieving reduced leakage fluxes through the altered geometry
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 significantly reduces leakage flux losses, resulting in higher power density and efficiency, allowing for smaller, lighter electrical machines with the same power output or using fewer magnets, while maintaining high torque delivery.
Implementation Method 1
The permanent magnets 4 are alternately polarized in opposite directions in the tangential direction, so that a magnetic north pole N always alternates with a magnetic south pole S in the circumferential direction of the rotor 1
Implementation Method 2
the base body 3 has a fastening ring 33 on its side facing the rotor shaft 2. The base body 3 is usually fixed to the rotor shaft 2 by means of the fastening ring 33. A holding lug 331 is provided on the fastening ring 33 for fastening each permanent magnet 4 and holds the permanent magnet 4 in the recess
Implementation Method 3
During operation, a control current in the stator (not shown) is controlled in such a way that a rotating magnetic field results, which takes the spoked rotor 1 with it
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The present invention relates to a rotor for an electric machine, comprising a rotor shaft which extends in an axial direction, and a basic body, which is arranged concentrically around the rotor shaft and is fastened on said rotor shaft for rotation therewith, wherein permanent magnets are embedded in the basic body, and wherein the basic body has collecting webs, which adjoin the permanent magnets, wherein the permanent magnets protrude beyond the collecting webs on that side of said permanent magnets which faces the rotor shaft. The present invention also relates to a rotor, in particular according to the invention, for an electric machine with a rotor shaft, which extends in an axial direction, and a basic body, which is arranged concentrically around the rotor shaft and is fastened on said rotor shaft for rotation therewith, wherein the basic body has sectors, which are spaced apart from the rotor shaft and between which in each case one permanent magnet is arranged in spider form, wherein the distance between the sectors and the rotor shaft is greater than the distance between the permanent magnets and the rotor shaft. The present invention also relates to an electric machine having the rotor according to the invention and a steering drive having the electric machine.