Marine Foil Wheel Propulsion Torque Management
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Solution Overview
Problem
Existing foil wheel propulsion systems for marine vehicles are not optimal for bollard pull conditions due to realistically limited foil motor torque, which restricts the achievement of an improved bollard pull thrust.
Innovation Solution
A method is introduced that involves controlling the pitch angle of foils in a foil wheel propulsion system using an angularly variable eccentricity, which is limited at specific angles to manage peak torque and enhance bollard pull thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a trochoidal pitch angle optimal for full speed torque loads is used, then the propulsion system performs well at full speed, but the bollard pull thrust is insufficient due to limited foil motor torque
Solution Approach 1:
The pitch angle is changed from a static trochoidal profile to a dynamic profile that varies with the rotational angle of the foil wheel. The pitch angle is dynamically adjusted to be more aggressive at specific rotational positions to maximize thrust during the power stroke, while being reduced at other positions to minimize reverse thrust and motor torque requirements, thereby improving bollard pull performance
Solution Approach 2:
The pitch angle parameter is modified from a constant trochoidal value to a variable value that changes throughout the rotation cycle. By changing the pitch angle parameter as a function of rotational angle, the system optimizes thrust generation at different phases of the foil wheel rotation, specifically enhancing bollard pull thrust while managing motor torque constraints
2Force
If the foil motor torque is increased to improve bollard pull thrust, then the thrust increases, but the device complexity and motor size increase
Solution Approach 1:
Instead of increasing motor torque capability, the system changes the pitch angle parameter profile to achieve better thrust utilization. By optimizing the pitch angle as a function of rotational angle, the system extracts more effective thrust from the available motor torque, improving bollard pull performance without requiring a larger or more complex motor
3Speed
If the pitch angle is optimized for full speed operation, then high speed performance is achieved, but the system is not adaptable to bollard pull conditions
Solution Approach 1:
The pitch angle control system is made dynamic and adaptive by making the pitch angle a function of the rotational angle. This dynamic profile can be adjusted based on operating conditions, allowing the system to optimize for either full speed performance or bollard pull conditions as needed, thereby improving adaptability across different operational scenarios
Solution Approach 2:
The variable pitch angle mechanism provides multi-functionality by enabling the same propulsion system to perform optimally in both full speed cruise conditions and stationary bollard pull conditions. The pitch angle profile can be adjusted to serve different operational requirements, making the system universal across multiple operating modes
Data Source
AI summary
A method for controlling a propulsion system of a marine vehicle is disclosed. A controller forms data on pitch angles of at least two foils, which are in a rotatable manner attached with a foil wheel, based on at least an angularly variable eccentricity of the at least two foils and an angle of rotation of the foil wheel. The variable eccentricity is limited at a portion of the angle of rotation of the foil wheel. An actuator arrangement receives the data from the controller and sets the at least two foils at the pitch angles based on the data.