Rotating Electric Machine Claw Pole Rotor Flux Control
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Solution Overview
Problem
Existing rotating electric machines, such as automotive alternators, face challenges in optimizing electric power generation and torque while minimizing counterelectromotive force, particularly when the field current is high, due to limitations in magnetic reluctance and inductance design, which affects their efficiency and power output.
Innovation Solution
The design incorporates a rotor with claw-shaped magnetic pole portions and permanent magnets arranged between them, where the magnetic path cross-sectional areas and permeance ratios are optimized to create a magnetic circuit that mimics an IPM rotor under load, enhancing magnetic flux utilization and reducing counterelectromotive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the field current is increased to improve power output, then the magnetic flux and torque increase, but the counterelectromotive force increases excessively reducing efficiency
Solution Approach 1:
The magnetic circuit is segmented into two independent paths: the d-axis magnetic circuit for field control and the magnet magnetic circuit for flux generation. This segmentation allows the field current and magnet flux to operate independently, enabling power output optimization without proportionally increasing counterelectromotive force.
Solution Approach 2:
The invention changes the magnetic circuit parameters by introducing permanent magnets with specific remanence values and configuring the d-axis magnetic circuit with controlled permeance. This allows the system to maintain high power output through magnet flux rather than relying solely on high field current, thereby reducing counterelectromotive force.
2Power
If the magnetic path cross-sectional area of the rotor is increased to improve magnetic flux utilization, then the electric power generation capability improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The d-axis magnetic circuit serves multiple functions: it provides the primary magnetic path for field control, supports the permanent magnets, and enables flux leakage control. This multi-functionality allows effective power generation without requiring excessive increases in magnetic path cross-sectional area.
Solution Approach 2:
The invention applies local quality optimization by configuring the d-axis magnetic circuit with specific permeance characteristics and positioning permanent magnets at locations that maximize flux utilization. This targeted approach improves power generation capability without uniformly increasing the entire rotor's magnetic path area, thereby controlling complexity.
3Loss of energy
If the d-axis magnetic circuit permeance is optimized to reduce counterelectromotive force, then the efficiency improves, but the manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes the d-axis magnetic circuit by adjusting permeance parameters through material selection and geometric configuration of the field core and yoke. These parameter changes achieve counterelectromotive force reduction through design rather than relying on tight manufacturing tolerances.
Solution Approach 2:
The magnetic circuit employs composite construction combining soft magnetic materials for the field core and yoke with permanent magnets. This composite approach allows permeance optimization through material properties rather than precise dimensional control, reducing manufacturing precision requirements while maintaining efficiency.
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 significantly improves electric power generation capability and torque output by effectively utilizing magnet magnetic flux, while suppressing counterelectromotive force and maintaining efficient operation across varying load conditions.
Implementation Method 1
each of the permanent magnets having magnetic poles formed therein so as to match the polarities induced in the pair of claw-shaped magnetic pole portions by magnetomotive force of the field coil
Implementation Method 2
Along the magnet magnetic circuit, magnetic flux generated by magnetic force of a corresponding one of the permanent magnets flows
Data Source
AI summary
In a rotating electric machine, a rotor includes a field core, a field coil and permanent magnets. The field core has a boss portion and claw-shaped magnetic pole portions. Each of the permanent magnets is arranged between one circumferentially-adjacent pair of the claw-shaped magnetic pole portions. A d-axis magnetic circuit and a magnet magnetic circuit share a magnetic path in at least parts thereof. Along the d-axis magnetic circuit, magnetic flux generated by the magnetomotive force of the field coil flows through the boss portion, one pair of the claw-shaped magnetic pole portions and a stator core. Along the magnet magnetic circuit, magnetic flux generated by the magnetic force of a corresponding one of the permanent magnets flows. The relationship of Ast>Af is satisfied, where Ast is a magnetic path cross-sectional area of a stator and Af is a magnetic path cross-sectional area of the rotor.