Hybrid Generator Rotor In-Situ Magnetization Method
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Solution Overview
Problem
Permanent magnet machines are difficult to regulate, leading to inefficiencies at low loads, while wound field machines suffer from winding losses and high costs, and existing hybrid machines do not effectively address these issues for in-situ magnetization and degaussing of generator rotors.
Innovation Solution
A method for in-situ magnetization and degaussing of generator rotors using a combination of excitation windings and permanent magnets, where a high current or voltage is applied to the windings in a decaying step function to magnetize or demagnetize the permanent magnets, allowing for safe and efficient handling and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If permanent magnets are used in the rotor, then machine efficiency is improved, but the machine becomes difficult to regulate and terminal voltage becomes load dependent
Solution Approach 1:
The patent combines permanent magnets and excitation windings in a hybrid rotor configuration. The permanent magnets provide the primary magnetic field for high efficiency, while the excitation windings enable regulation capability by allowing control of the magnetic field strength through variable current input, thus merging the advantages of both permanent magnet and wound field machines.
Solution Approach 2:
The patent introduces dynamic control capability to the permanent magnet machine by incorporating excitation windings that can vary the magnetic field strength. This allows the machine to adapt its terminal voltage and power factor according to load conditions, transforming a static permanent magnet system into a dynamically controllable hybrid system.
2Adaptability or versatility
If wound field machines are used, then regulation over wide load range is improved, but winding losses increase and machine efficiency decreases
Solution Approach 1:
The patent uses permanent magnets to provide the primary and sufficient magnetic field for machine operation, requiring only partial excitation current in the windings for regulation purposes. This partial action approach reduces winding losses significantly compared to full-wound field machines while maintaining regulation capability.
3Manufacturing precision
If high current is applied to magnetize permanent magnets in-situ, then magnetization is achieved, but excessive force may damage the rotor or stator
Solution Approach 1:
The patent applies magnetizing current in periodic pulses rather than continuous high current. This periodic action allows the magnetic domains to gradually align without subjecting the rotor-stator assembly to continuously excessive electromagnetic forces, reducing mechanical stress while achieving complete magnetization over time.
Solution Approach 2:
The patent performs preliminary alignment and securing of the rotor within the stator before applying the magnetizing current. This preliminary action ensures proper positioning and mechanical support, preventing damage during the magnetization process while enabling effective magnetic field application.
4Reliability
If the rotor is handled in a magnetized state, then permanent magnet properties are maintained, but handling safety is compromised due to strong magnetic fields
Solution Approach 1:
The patent applies a preliminary anti-action by using degaussing current in the opposite direction to neutralize the magnetic field before handling operations. This creates a magnetically neutral state that eliminates the harmful magnetic forces and attraction forces during assembly, disassembly, and transport, while the permanent magnets retain their properties for operational use.
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
Enables efficient magnetization and degaussing of permanent magnets within the rotor, improving handling safety and reducing manufacturing and operational costs by allowing the rotor to be managed in a demagnetized state, thus enhancing the operational flexibility and efficiency of hybrid synchronous machines.
Implementation Method 1
applying a current to the excitation windings... magnetize the permanent magnets
Implementation Method 2
permanent magnets or excitation windings can be situated on either the rotor or the stator... to provide MMF (magnetomotive force) that provides the magnetic flux
Data Source
AI summary
A method for in-situ magnetization of a generator rotor is provided. The generator has a stator and the rotor is located inside the stator. An air gap is formed between an outer radial portion of the rotor and an inner radial portion of the stator. The rotor has a plurality of excitation windings and a plurality of permanent magnets. The method includes the step of applying a current to the excitation windings, and the current is greater than a normal excitation current. A maintaining step maintains the current for a time period sufficient to magnetize the permanent magnets. The magnetization of the permanent magnets occurs on the rotor in-situ and while the rotor is inside the stator.