Superconducting Generator Phase Shifting for Eddy Current Reduction
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Solution Overview
Problem
Superconducting electric machines face significant heat losses due to eddy currents generated by spatial and time harmonics in low-temperature regions, which require substantial work to reject heat to ambient, necessitating a solution to minimize these losses.
Innovation Solution
A superconducting wind turbine generator with a controllable phase shifting capability, utilizing a multiphase armature winding set and a superconducting field winding set separated by a gap, where a controller adjusts the phase shift among armature windings to minimize heat rejection by controlling the controllable power converter, particularly by modifying phase shift angles based on temperature and cryocooler inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If superconducting coils are used to generate magnetic fields in low-temperature zones, then generator efficiency and power density are improved, but eddy currents are induced by spatial and time harmonics which generate heat that must be rejected requiring large amounts of work
Solution Approach 1:
The patent applies parameter changes by modifying the frequency and phase of armature windings to minimize harmonic content. Specifically, the system varies the electrical frequency of armature windings and adjusts phase relationships between multiple armature winding sets to reduce spatial and time harmonics, thereby minimizing eddy current losses in the superconducting field winding while maintaining generator power output
2Loss of energy
If the number of cryocoolers is increased to reject more heat, then heat rejection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent converts the harmful effect of harmonics into a beneficial control mechanism. By intentionally introducing controllable phase shifts and frequency variations in the armature windings, the system transforms what would normally be unpredictable harmonic losses into a controllable parameter that can be optimized to minimize eddy currents, thereby reducing the heat rejection burden on cryocoolers
3Loss of energy
If spatial and time harmonics are reduced to minimize eddy currents, then heat generation is reduced, but control complexity increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring the heat generation in low-temperature zones and adjusting the phase and frequency of armature windings accordingly. The controller receives temperature feedback from the superconducting field winding region and dynamically modifies winding parameters to maintain optimal harmonic reduction, creating a closed-loop system that balances control complexity with loss minimization
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 approach reduces heat rejection in low-temperature regions, minimizing the workload on cryocoolers, enhancing efficiency, reliability, and reducing costs by effectively canceling non-synchronous field components and reducing the number of cryocoolers needed.
Implementation Method 1
superconducting generators include at least one superconducting coil which generates a static or rotating magnetic field
Implementation Method 2
at least one armature coil which also generates a static or rotating magnetic field that interacts with the field from the superconducting coil
Implementation Method 3
These spatial and time harmonics can induce eddy currents within the superconducting coil and surrounding hardware. These eddy currents generate heat
Implementation Method 4
a controller configured to control switching operations of the controllable power converter to effect a phase shift among the plurality of armature windings
Data Source
AI summary
A wind turbine includes a superconducting generator having an armature and a superconducting field winding set. The armature includes at least one multiphase armature winding set having a plurality of armature windings. The superconducting field winding set is separated by a gap from the armature. The superconducting field winding set includes a plurality of field windings, wherein one of the armature winding set and superconducting field winding set is connectable to rotate with a rotating component of the wind turbine and another of the armature and the superconducting field winding set being non-rotating. The wind turbine also includes a controllable power converter coupled to the at least one multiphase armature winding set and a controller configured to control switching operations of the controllable power converter to effect a phase shift among the plurality of armature windings.