Jack-up Platform Leg Control via Closed-Loop Variable Speed Drives
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Solution Overview
Problem
Existing jack-up platforms lack efficient control mechanisms for their driving mechanisms, leading to suboptimal performance and reliability in support leg operations, especially when using induction motors which experience high motor losses and heat dissipation during hold positions.
Innovation Solution
Integration of a closed-loop control system with a bi-directional electronic bus connecting variable speed drives to a control unit, allowing for precise speed and torque control, and the use of variable speed drives that can operate with both induction and permanent magnet motors, reducing motor stresses and enabling infinitely variable speed operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If induction motors are used for driving support legs, then the platform can achieve basic movement functionality, but motor losses and heat dissipation increase during hold positions
Solution Approach 1:
The patent changes the motor type from induction motor to permanent magnet motor, which fundamentally alters the motor's efficiency characteristics and eliminates the high motor losses and heat dissipation issues during hold positions that plague induction motors
2Ease of operation
If permanent magnet motors are used for moving support legs, then high torque and infinitely variable speed are achieved, but efficient control mechanism is lacking
Solution Approach 1:
The patent implements a closed-loop control system with feedback mechanisms including encoders for position feedback and current sensors for torque feedback, enabling precise control of the permanent magnet motors while maintaining system stability through proportional-integral-derivative (PID) control algorithms
Solution Approach 2:
The patent replaces traditional mechanical braking systems with electronic control of the permanent magnet motors themselves, using the motors' electromagnetic characteristics to provide both drive and holding functions, thereby simplifying the overall control system despite the added electronic control complexity
3Adaptability or versatility
If mechanical brakes are used for holding the platform, then position holding is achieved, but the system requires additional mechanical components and cannot provide infinitely variable speed control
Solution Approach 1:
The patent makes the permanent magnet motor perform multiple functions: it provides both the drive function during movement and the holding function during position maintenance, eliminating the need for separate mechanical brakes and enabling infinitely variable speed control across the entire operating range
4Ease of operation
If separate driving mechanisms are used for each support leg, then independent leg control is achieved, but the overall system coordination and balance control becomes complex
Solution Approach 1:
The patent combines the control of all four support legs into a single centralized control system that coordinates the permanent magnet motors on each leg, using feedback from encoders and sensors to automatically balance the platform and simplify operation despite the independent actuation capability of each leg
Data Source
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AI summary
The invention relates to a jack-up platform (1) comprising a hull (2) and at least three longitudinally movable support legs (3) for said hull (1), at least one of said support legs (3) comprising at least one variable speed drive (8, 8A1to 8F2) as a part of a leg driving mechanism, wherein the platform (1) comprises a closed-loop control unit (7) for said driving mechanism, the closed-loop control unit (7) being connected with said variable speed drive (8, 8A1 to 8F2) via a bi-directional electronic bus (16) for transmitting control parameters (M*, M, N, R).