Variable Overlap Brushless DC Generator for Constant Frequency Output
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Solution Overview
Problem
Current renewable energy generators, such as wind and hydrokinetic turbines, face challenges in converting variable speed and frequency inputs into constant frequency and voltage outputs, leading to inefficiencies and maintenance issues due to the use of gearboxes and commutators, which are prone to failure and wear.
Innovation Solution
A commutator-free and brushless direct current generator system utilizing a variable overlap generator and Hummingbird speed converter to adjust the axial overlap between the rotor and stator, allowing for independent control of speed, torque, and power, and generating alternating current power at constant frequency and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If gearboxes and commutators are used in renewable energy generators, then speed and frequency conversion is achieved, but reliability deteriorates due to wear and overheating
Solution Approach 1:
The patent removes the gearbox and commutator components from the generator system. The direct drive generator design eliminates the gearbox by directly coupling the turbine rotor to the generator rotor, and the generator itself is designed without a commutator, using brushless excitation instead. This extraction of problematic components directly resolves the reliability issue while maintaining speed conversion functionality through alternative means.
Solution Approach 2:
The patent replaces the mechanical commutator system with a brushless electronic excitation system. Instead of using a mechanical commutator to switch current directions in the rotor windings, the system uses electronic controllers and rectifiers to provide DC excitation current to the rotor field windings through slip rings or direct connection, eliminating the mechanical wear and sparking associated with commutators.
2Power
If commutators and brushes are used, then direct current generation is achieved, but maintenance requirements increase due to wear
Solution Approach 1:
The patent removes the commutator and brush components from the generator design. By eliminating these wear-prone parts, the system achieves direct current generation capability through alternative means (using diode rectifiers and brushless excitation) while dramatically reducing maintenance requirements as there are no components subject to frictional wear and replacement.
Solution Approach 2:
The patent replaces the expensive and labor-intensive commutator and brush assembly with simpler, more durable components. The use of solid-state diode rectifiers and brushless excitation systems replaces components that would otherwise require periodic replacement due to wear, reducing both the cost and complexity of maintenance over the system's lifetime.
3Adaptability or versatility
If variable speed inputs are converted to constant frequency outputs, then grid compatibility is improved, but device complexity increases
Solution Approach 1:
The patent employs a direct drive variable speed generator design where the rotor speed can vary with wind or water flow conditions, but the electrical output frequency is kept constant through electronic control. The generator's magnetic field rotation speed is decoupled from the mechanical input speed through electronic rectification and inversion, allowing the system to adapt to varying input speeds while maintaining constant frequency output for grid compatibility without requiring a rigid mechanical speed conversion system.
Solution Approach 2:
The patent changes the control parameter from mechanical speed conversion to electronic frequency control. Instead of using a gearbox to mechanically enforce a fixed rotor speed, the system allows the rotor to spin at variable speeds and uses electronic rectifiers and inverters to convert the variable frequency AC output into constant frequency AC suitable for grid connection. This parameter change from mechanical to electronic control reduces device complexity.
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 solution enables high-efficiency, low-maintenance electric power generation from renewable sources, reducing the need for gearboxes and commutators, and providing stable power output suitable for electric grids, even under varying wind and water flow conditions.
Implementation Method 1
A commutator-free and brushless direct current generator system utilizing a variable overlap generator and Hummingbird speed converter to adjust the axial overlap between the rotor and stator
Data Source
AI summary
Three controls, three variable gear assemblies, an optional hatch or variable propeller pitch, and a variable overlap generator (VO generator), as well as one or more commutator and brush-less free direct current generators may be used independently and together to provide constant frequency and voltage output power and to increase the amount of output power generated with the same input water flow or wind speed in a plurality of embodiments useful in wind power generation and water renewable energy generators for any of tidal and ocean current or wave conditions. Two Transgear™ assemblies side-by-side and sharing the same central shaft may comprise a constant speed motor control, produce required constant frequency and voltage and be reduced in part count and complexity. The variable overlap generator of a marine hydrokinetic or wind power generator may be used as a low torque generator, a high power-rated generator or a control in these applications and may generate more electric power than a conventional fixed power generator (the rotor axially aligned to overlap the stator in a conventional manner) over a wider input range. An electromotive force (EMF) embodiment generates alternating current at constant frequency and voltage in varying wind and water speed conditions.