Linear Generator PTO Control for Multi-Frequency Wave Energy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wave Energy Converters face challenges in efficiently extracting energy from ocean waves due to their dynamic and multi-frequency nature, as existing systems lack optimal controls and capable generator and power train systems to handle varying frequency components and rapid operational changes.
Innovation Solution
A Power Take-off system integrating a linear electric motor-generator with both low-level and high-level control systems, including a Vernier Effect Permanent Magnet Linear Generator, enables efficient energy extraction by predicting and commanding optimal operating states and adapting to changing wave conditions through a direct drive design without the need for gearboxes or transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple controller providing mechanical damping coefficient is used to maximize power from the dominant wave frequency, then the control system is simple and easy to implement, but the energy extraction efficiency decreases when dealing with multi-frequency wave components and rapid operational changes
Solution Approach 1:
The control system transitions from static mechanical damping to dynamic electrical control through a linear electric motor-generator. This enables real-time adjustment of operational parameters (force, velocity, position) to match rapidly changing wave conditions across multiple frequencies, resolving the contradiction by making the system adaptive rather than fixed.
Solution Approach 2:
The system changes the fundamental operating parameters from mechanical damping coefficient control to electrical parameter control (current, voltage, frequency). This allows continuous adjustment of force and velocity profiles to optimize energy extraction from varying wave spectra, improving productivity while maintaining manageable control complexity through electronic rather than mechanical means.
2Adaptability or versatility
If traditional mechanical PTO systems with gearboxes and transmissions are used, then the system structure is well-established, but the system cannot adapt to rapid operational changes and multi-frequency wave conditions on sub-second time scales
Solution Approach 1:
The patent replaces the mechanical power train system (gearboxes, transmissions, linkages) with an electric motor-generator system. This substitution eliminates mechanical complexity while providing superior adaptability through electrical control, allowing sub-second response times to changing wave conditions without the inertia and mechanical constraints of traditional systems.
Solution Approach 2:
The linear electric motor-generator serves multiple functions simultaneously: it acts as both motor and generator, provides mechanical force control, enables electrical energy extraction, and offers adaptive control across varying frequencies. This multi-functionality reduces overall system complexity while improving adaptability compared to dedicated mechanical components.
3Productivity
If a linear electric motor-generator with dual control systems is implemented to achieve high energy conversion efficiency, then the energy extraction performance improves, but the device complexity increases
Solution Approach 1:
The patent merges the motor and generator functions into a single linear electric machine, eliminating the need for separate mechanical components and reducing overall system complexity. The high-level and low-level control systems are integrated with the power electronics, creating a unified control architecture that manages both force control and energy extraction simultaneously, resolving the contradiction by combining functions rather than adding separate systems.
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 integrated system enhances energy conversion efficiency by optimally managing power extraction across multiple frequency components and rapid operational changes, improving the overall performance of Wave Energy Converters.
Implementation Method 1
the linear electric motor-generator comprises a Vernier Effect Permanent Magnet Linear Generator
Implementation Method 2
extracting mechanical energy from the ocean and converting it into electrical energy
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A wave energy converter (10) incorporates a floating body(12) and a reaction body (16) engaging the floating body wherein the reaction body is static or oscillating out of phase relative to the floating body. A power take-off (PTO) (18) has at least one direct drive linear generator (50), a high level controller (30) responsive to sensors (31) engaged to the direct drive linear generator and providing a PTO force change command (dFPTO) and a low level controller (32) receiving the PTO force change command and providing control signals to power electronics (34) connected to the direct drive linear generator. The direct drive linear generator is operable responsive to the control signals to achieve optimal power extraction performance with high force at low speed with operation in two physical directions and operating as both a motor and a generator for a total of four quadrants of control.