Lundell Rotor Magnetic Circuit Design for Back-EMF Control
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Solution Overview
Problem
The power generator with an IPM rotor faces high back-electromotive force, while those with a Lundell rotor have low power output, necessitating an improvement in power generation performance.
Innovation Solution
The Lundell rotor's magnetic resistance and inductance are adjusted to match those of the IPM rotor by increasing the magnetic resistance of the field core and altering the permeance ratios, allowing the Lundell rotor to operate similarly to the IPM rotor under electrical load, thereby enhancing power generation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an IPM rotor with permanent magnets embedded in the outer peripheral portion is used, then torque and power generation performance are improved, but back-electromotive force becomes excessively high
Solution Approach 1:
The invention changes the magnetic circuit parameters by introducing a specific magnetic resistance ratio relationship (Pst/Prt ≥ 1.5) between the stator and rotor magnetic circuits. This parameter adjustment allows the Lundell rotor to achieve torque characteristics similar to IPM rotors while controlling the back-electromotive force to acceptable levels through optimized magnetic flux distribution.
2Object-generated harmful factors
If a Lundell rotor with claw-shaped magnetic pole parts is used, then back-electromotive force is reduced to acceptable levels, but power output and torque are insufficient
Solution Approach 1:
The invention optimizes the magnetic circuit parameters by establishing a specific permeance ratio relationship between stator and rotor magnetic circuits. This allows the traditional Lundell rotor structure to achieve enhanced power output and torque by improving magnetic flux utilization efficiency while maintaining compatible back-electromotive force characteristics.
Solution Approach 2:
The invention creates a composite magnetic circuit system that combines the Lundell rotor's claw-shaped magnetic pole structure with optimized magnetic path design. This composite approach integrates the advantages of simple structure with improved magnetic flux distribution to achieve both acceptable back-electromotive force and enhanced power output.
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 enables the Lundell rotor to produce the same torque as the IPM rotor, improving power generation efficiency and reducing back-electromotive force, thus enhancing overall performance.
Implementation Method 1
a field winding (33) that is wound on the outer peripheral side of the boss part to generate a magnetomotive force by energization
Implementation Method 2
permanent magnets (34, 34A) that are arranged with an axis of easy magnetization oriented in the circumferential direction between the circumferentially adjacent claw-shaped magnetic pole parts and have magnetic poles formed to match the alternating polarities of the claw-shaped magnetic pole parts produced by the magnetomotive force of the field winding
Implementation Method 3
a d-axis magnetic circuit (36) in which a magnetic flux formed by the magnetomotive force of the field winding flows through the boss part, the pair of claw-shaped magnetic pole parts, and the stator core
Data Source
AI summary
A vehicle alternating-current power generator includes a stator formed by winding an armature winding on a stator core and a rotor arranged on the radial inside of the stator. The rotor includes a field core having a boss part and a plurality of claw-shaped magnetic pole parts, a field winding that is wound on the outer peripheral side of the boss part, and a permanent magnet that is arranged between the circumferentially adjacent claw-shaped magnetic pole parts. A d-axis magnetic circuit formed by magnetomotive force of the field winding and at least part of first and second magnet magnetic circuits formed by magnetic force of the permanent magnet are shared. When an electrical load is connected to the rotor, the relationship between a permeance Prt of the d-axis magnetic circuit and a permeance Pst of a q-axis magnetic circuit is set to satisfy Pst>Prt.