Variable-Field Rotating Machine Pole Layout for Magnetic Force Balance
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Solution Overview
Problem
Variable field motors generate unbalanced magnetic attractive forces due to combined magnetomotive forces from armature, DC field winding, and permanent magnets, leading to noise and axial displacement, which are difficult to suppress through increased air-gap length in manufacturing.
Innovation Solution
A rotating electric machine design with a stator and rotor configuration where permanent magnets and protrusions are alternately arranged, ensuring the number of pole pairs of armature, field winding, and field poles satisfy specific conditions to prevent unbalanced magnetic attractive forces, including all having the same polarity and specific relational differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the air-gap length between the stator and the rotor is increased to suppress the unbalanced magnetic attractive force, then the influence of the unbalanced magnetic attractive force is reduced, but the manufacturing difficulty increases
Solution Approach 1:
The invention changes the pole configuration parameters by setting the number of pole pairs of the armature winding (Pa), the number of pole pairs of the field winding (Pf), and the number of poles of the field pole (Pr) to satisfy specific relationships: |Pa−Pf|≠1, |Pr−Pf|≠1, and |Pa−Pr|≠1, with Pr being an even number. This parameter optimization eliminates the unbalanced magnetic attractive force without requiring air-gap length adjustment, thus avoiding manufacturing difficulties.
2Adaptability or versatility
If a variable field motor is designed to achieve a wide operating range by adjusting the field amount, then the operating range is expanded, but unbalanced magnetic attractive forces are generated causing noise and axial displacement
Solution Approach 1:
The invention optimizes the pole configuration parameters (Pa, Pf, Pr) to satisfy specific relationships that eliminate unbalanced magnetic attractive forces. This allows the variable field motor to achieve a wide operating range through field adjustment while avoiding the generation of harmful unbalanced forces, thus resolving the contradiction between adaptability and harmful factor generation.
Solution Approach 2:
The invention employs asymmetric pole configuration where the number of poles of the field pole (Pr) is set to an even number, and the relationships between Pa, Pf, and Pr are specifically constrained. This asymmetric configuration prevents the formation of unbalanced magnetic attractive forces while maintaining the variable field capability for wide operating range.
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 design suppresses rotation axis eccentricity and vibration by eliminating unbalanced magnetic attractive forces, enhancing stability and reducing noise.
Implementation Method 1
a field pole is formed in the plurality of protrusions by energization to the field winding
Implementation Method 2
the rotor includes a plurality of permanent magnets arranged in a circumferential direction of a rotation axis
Implementation Method 3
there are three magnetomotive forces, namely, a pole due to an armature winding of a stator, a pole due to a DC field winding, and a pole due to a permanent magnet and an iron pole
Data Source
AI summary
A rotating electric machine according to the present disclosure is a rotating electric machine including a stator and a rotor, in which the rotor includes a plurality of permanent magnets arranged in a circumferential direction of a rotation axis and a plurality of protrusions arranged in the circumferential direction, the stator includes a plurality of teeth, an armature winding wound around the plurality of teeth, and a field winding wound around the plurality of teeth, a field pole is formed in the plurality of protrusions by energization to the field winding and the plurality of permanent magnets, the plurality of permanent magnets and the plurality of teeth are alternately arranged at intervals in the circumferential direction to form the field pole, all the permanent magnets have the same polarity, wherein, |Pa−Pf|≠1, |Pr−Pf|≠1, and |Pa−Pr|≠1, and Pr is even.