Contra-rotating Rotor Electrical Machine Design
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Solution Overview
Problem
Conventional wind or water turbines face challenges in balancing tip speed, rotor diameter, and generator size, leading to the need for expensive and maintenance-intensive gearboxes, and contra-rotating turbines complicate electrical connections, increasing cost and complexity.
Innovation Solution
An electrical machine with a concentric arrangement of a field magnet stator, an armature stator, and contra-rotating magnetizable rotors, which transmit magnetic flux to induce an electromotive force, eliminating the need for rotating magnets and slip rings, and utilizing an epicyclic gearbox or magnetic clutch for synchronous rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a gearbox is used to connect turbine and generator, then speed matching is achieved, but cost and maintenance requirements increase
Solution Approach 1:
The patent removes the gearbox from the system entirely by using a direct-drive configuration where the turbine rotor is magnetically coupled to the generator rotor through a magnetic clutch, eliminating the need for mechanical gear transmission while still achieving speed matching through magnetic field interaction
Solution Approach 2:
The magnetic clutch acts as an intermediary between the turbine and generator, using magnetic fields to transmit rotational motion and achieve speed matching without direct mechanical contact or gear mechanisms, thereby reducing complexity and maintenance requirements
2Power
If contra-rotating rotors are used in turbine, then power output increases, but electrical connection complexity increases
Solution Approach 1:
The patent replaces the mechanical electrical connection system (slip rings and brushes) with a magnetic field-based system where the rotating magnetic field of the turbine rotor directly induces current in the generator stator windings, eliminating the need for sliding electrical contacts while maintaining power transmission
Solution Approach 2:
The magnetic field serves as an intermediary that transfers energy from the contra-rotating turbine rotors to the generator without requiring direct electrical connections to rotating parts, thus simplifying the electrical connection system while maintaining high power output
3Power
If larger diameter turbine is used, then power output increases, but tip speed decreases
Solution Approach 1:
The patent uses a dynamic magnetic coupling system with adjustable magnetic clutch engagement that allows the turbine to operate at optimal tip speeds while the magnetic field transmission adapts to maintain efficient power transfer across varying rotational speeds, enabling larger diameter turbines to maintain high tip speeds
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 achieves a higher pole passing frequency, potentially doubling power output while reducing costs and complexity by simplifying construction and eliminating the need for brushes and slip rings, and allowing for direct drive without a gearbox, enhancing efficiency and reliability.
Implementation Method 1
at least a portion of each of the rotors is magnetisable so as to transmit magnetic flux between the field magnet and the armature thereby inducing an electromotive force
Data Source
Figure 1~2
Figure 3a~3e
Figure 4~5
AI summary
An electrical machine comprising: a first stator member (16) having a field magnet (22); a second stator member (18) forming an armature, the second stator member (18) being spaced from the first stator member (16); and a pair of contra-rotatable rotors (12a, 12b) disposed between the first and second stator members (16, 18); wherein at least a portion (14) of each of the rotors (12a, 12b) is magnetisable so as to transmit magnetic flux between the field magnet (22) and the armature.