Ship Drive System with Frequency Converter and Electrical Shaft
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Solution Overview
Problem
Conventional propulsion systems for light and fast ships, such as mechanical and hybrid diesel-electric drives, face inefficiencies at low-load operations, high vibration issues, and excessive weight, making them unsuitable for light ships with variable power requirements.
Innovation Solution
A purely electric hybrid propulsion system with a frequency converter and a drive generator, allowing efficient operation in multiple power ranges, using an electrical shaft for coupling and high-temperature superconductor generators for reduced weight and increased network rigidity, along with dual drive electric motors for redundancy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional mechanically propelled systems with diesel engines, transmissions, and shafts are used, then propulsion function is achieved, but efficiency at low-load mode deteriorates and weight increases
Solution Approach 1:
The patent replaces the conventional mechanical transmission system (diesel engine, gearbox, shafts) with an electric propulsion system consisting of electric motors, frequency converters, and a modular power distribution network. This substitution eliminates mechanical losses, enables efficient low-load operation through variable frequency control, and reduces overall system weight by removing heavy mechanical transmission components while maintaining propulsion functionality.
Solution Approach 2:
The patent implements dynamic adaptability through frequency converters that can adjust motor operating frequency and voltage according to actual propulsion needs. This allows the electric motors to operate at optimal efficiency points across varying load conditions, particularly improving low-load efficiency while maintaining the ability to deliver high power when needed, thus resolving the efficiency-weight trade-off.
2Adaptability or versatility
If combined mechanical drive systems with multiple drive motors and gear stages are used, then propulsion versatility is improved, but device complexity increases and vibration problems worsen
Solution Approach 1:
The patent designs electric motors that can operate in multiple modes (motoring, generating, braking) through a unified electric control system. The same motor hardware provides both propulsion and energy recovery functions, eliminating the need for separate mechanical systems for different propulsion modes. This universal approach maintains versatility while dramatically reducing system complexity compared to combined mechanical drive systems.
Solution Approach 2:
The patent replaces complex mechanical gear stages, couplings, and speed adjustment mechanisms with electronic frequency conversion and motor control. The frequency converters electronically adjust motor speed and torque without mechanical transmission, eliminating gearboxes, clutches, and other complex mechanical components that generate vibration and increase system complexity.
3Use of energy by moving object
If electromechanical hybrid CODLAG drives with hierarchical energy supply are used, then propulsion efficiency is improved, but device complexity increases and weight increases
Solution Approach 1:
The patent segments the power distribution system into modular units with independent frequency converters for each motor. Each module can operate independently or in coordination, allowing flexible energy distribution without complex hierarchical control. This modular segmentation simplifies the energy management system while maintaining high efficiency through optimized power allocation to different motors based on instantaneous propulsion requirements.
4Reliability
If all-electric propulsion systems with high redundancy are used, then reliability is improved, but weight increases significantly
Solution Approach 1:
The patent merges the propulsion system with the on-board electrical network, allowing the same electrical infrastructure to serve both ship operations and propulsion functions. The electric motors are directly coupled to the ship's electrical system through frequency converters, eliminating the need for separate heavy-duty power transmission systems. This integration achieves high reliability through shared redundant electrical pathways while minimizing weight by consolidating electrical 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
The system achieves efficient propulsion across various speed ranges with reduced weight and increased reliability, enabling efficient operation at low and high speeds while minimizing energy distribution complexities and weight, making it suitable for light ships.
Implementation Method 1
a frequency converter via which electrical energy from the on-board electrical system can be supplied to the propulsion electric motor
Implementation Method 2
a drive generator driven by the drive machine
Implementation Method 3
an electrical shaft for connecting the propulsion electric motor to the drive generator
Data Source
Figure 1
AI summary
The invention relates to a drive system (1) for a ship which has an onboard electrical system (2) with a fixed onboard electrical system frequency. The drive system (1) comprises an electric drive motor (10, 20) for driving the ship, a frequency converter (11, 21) via which electrical energy can be supplied from the onboard electrical network (2) to the electric drive motor (10, 20), a drive machine (13, 23), a drive generator (14, 24) which can be driven by the drive machine (13, 23), and an electric shaft (15, 25) for connecting the electric drive motor (10, 20) to the drive generator (14, 24). The electric drive motor (10, 20) can thereby be optionally driven by the frequency converter (11, 21), by the drive generator (14, 24), or by the frequency converter (11, 21) and the drive generator (14, 24). In addition, an operating mode is preferably provided, in which power generated by the drive machine (13, 23) is supplied into the onboard network (2) via the frequency converter (11, 21).