AC Power Bus Propulsion for UUV Speed-Fuel Trade-off
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Solution Overview
Problem
Unmanned underwater vehicles face a trade-off between effective range and sprint speed due to limitations in existing propulsion systems, which often require significant fuel expenditure for high-speed operations and compromise on range when operating at lower speeds.
Innovation Solution
An AC bus-based propulsion system featuring a turbine engine with a voltage-controlled generator and induction motor, where the AC output is independent of rotational speed, allowing for efficient power management and optimized speed control, enabling peak turbine efficiency and reduced fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional propulsion systems are used to achieve high sprint speed, then sprint speed capability is improved, but fuel consumption increases and effective range decreases
Solution Approach 1:
The propulsion system is segmented into two independent power sources: a turbine engine for high-speed sprint operations and a battery-powered electric motor for low-speed cruise operations. This segmentation allows each power source to operate independently in its optimal performance range, eliminating the need for the turbine to consume excessive fuel during low-speed operations while maintaining sprint speed capability when needed.
Solution Approach 2:
The system dynamically switches between two propulsion modes based on operational requirements. A controller monitors vehicle speed and operational state, automatically engaging the turbine engine when high speed is required and the electric motor when cruise speed is sufficient. This dynamic operation optimizes fuel consumption by avoiding turbine operation during low-power demands while preserving sprint speed capability on demand.
2Adaptability or versatility
If turbine engine operates at variable speeds to match vehicle speed requirements, then speed adaptability is improved, but turbine efficiency decreases and fuel consumption increases
Solution Approach 1:
The propulsion system segments speed control functions between two power sources: the turbine engine operates at a fixed optimal speed for high-power output, while the electric motor provides variable speed control for cruise operations. This segmentation allows the turbine to maintain peak efficiency at constant speed while the electric motor handles speed variability, resolving the contradiction between speed adaptability and fuel efficiency.
Solution Approach 2:
The system replaces the traditional mechanical coupling between turbine and propeller with an electrical coupling through a generator and motor. The turbine drives a generator that produces AC power, which then drives the propeller through an induction motor. This substitution allows independent control of turbine speed from propeller speed, enabling the turbine to operate at fixed optimal speed while the motor provides variable speed control for adaptability.
3Device complexity
If turbine is mechanically coupled to propulsor for direct drive, then system complexity is reduced, but speed control flexibility and fuel efficiency are compromised
Solution Approach 1:
The patent replaces the direct mechanical coupling between turbine and propeller with an electrical intermediate system. The turbine connects to a generator that produces AC power, which then connects to an induction motor that drives the propeller. This electrical substitution decouples the turbine speed from propeller speed, allowing the turbine to operate at fixed optimal speed for fuel efficiency while the motor provides speed control flexibility, with the added benefit of enabling battery integration for dual-mode operation.
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 enhances the range and sprint speed capabilities of unmanned underwater vehicles by optimizing fuel usage and reducing system weight and size, allowing for increased fuel storage and extended operation duration.
Implementation Method 1
an electrical generator mechanically connected to the rotational output and electrical connected to an Alternating Current (AC) power bus, wherein a magnitude of an AC output of the electrical generator is independent of rotational speed of the rotational input
Implementation Method 2
an electrical motor connected to the AC power bus, and including a mechanical output
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A propulsion system (400) for an unmanned underwater vehicle (100) includes a turbine engine (160) having a rotational output, an electrical generator mechanically connected to the rotational output and electrically connected to an Alternating Current (AC) power bus (430). A magnitude of an AC output of the electrical generator is independent of rotational speed of the rotational input. An electrical motor connected to the AC power bus, and includes a mechanical output.