Rotating Electric Machine Tubular Short-Circuiting Member
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Solution Overview
Problem
Conventional rotating electric machines experience increased AC copper loss in the armature coil due to magnetic flux from the rotor, as the magnetic flux flows axially and crosses the coil end parts, leading to inefficiencies and heat dissipation.
Innovation Solution
Incorporating a tubular short-circuiting member radially outside the magnetic pole portions of the rotor, which connects adjacent magnetic poles and redirects the magnetic flux radially to the stator, thereby minimizing the axial component of the magnetic flux and reducing AC copper loss. The short-circuiting member is positioned within the axial range of the stator core and has a radial thickness that allows for efficient flux concentration without excessive leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If no short-circuiting member is provided, then the structure is simple, but AC copper loss increases due to magnetic flux crossing the coil end parts
Solution Approach 1:
A tubular short-circuiting member is introduced as an intermediary component between the rotor and stator. This member provides a dedicated magnetic flux path that redirects flux away from the coil end parts, thereby reducing AC copper loss while maintaining structural simplicity
Solution Approach 2:
The harmful axial magnetic flux component is extracted and redirected through the short-circuiting member. By separating the flux path from the coil end parts, the harmful effect is removed while the beneficial magnetic coupling is preserved
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 effectively reduces AC copper loss in the armature coil by redirecting magnetic flux, minimizing heat dissipation and enhancing the machine's efficiency by concentrating magnetic flux on the short-circuiting member, which then transfers it to the stator, thereby reducing harmonic iron loss and improving quietness.
Implementation Method 1
the magnetic flux flows from axially outer end portions of the rotor to axial ends of the stator, crossing the coil end parts of the armature coil
Implementation Method 2
a tubular short-circuiting member that is arranged radially outside the magnetic pole portions to cover radially outer surfaces of the magnetic pole portions and magnetically connects each circumferentially-adjacent pair of the magnetic pole portions
Implementation Method 3
When the N-pole magnetic flux and the S-pole magnetic flux alternately flow with rotation of the rotor, portions of the armature coil of the stator which are located close to the rotor are subjected to a strong alternating magnetic field, causing copper loss (i.e., so-called AC copper loss) to occur in the armature coil
Implementation Method 4
it is also possible to reduce eddy current loss in the magnetic pole portions
Data Source
AI summary
A rotating electric machine includes a stator and a rotor. The stator includes a stator core and an armature coil wound on the stator core. The rotor is arranged radially inside the stator to radially face the stator. The rotor includes: a field core having a plurality of magnetic pole portions for respectively forming a plurality of magnetic poles the polarities of which are alternately different in a circumferential direction; a field coil wound on the field core; and a tubular short-circuiting member that is arranged radially outside the magnetic pole portions to cover radially outer surfaces of the magnetic pole portions and magnetically connects each circumferentially-adjacent pair of the magnetic pole portions. The short-circuiting member is provided within an axial range between two axial ends of the stator core.