Variable Pitch Propeller Stopping Maneuver Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Watercraft with controllable pitch propellers face challenges in rapid braking, particularly in ensuring the shortest stopping distance without exceeding critical propeller speeds, and managing the 'windmilling' effect during emergency stops, which complicates the stability of onboard networks and requires costly regenerative converters.
Innovation Solution
A method involving the determination of a characteristic curve for blade angle and propeller speed profiles that allows the drive system to achieve the shortest stopping distance while preventing propeller speed from exceeding a critical value, using sensors to monitor and adjust motor torque, blade angle, and propeller speed, and accounting for forces like hull resistance and thrust during the stopping maneuver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the propeller acts as a turbine during emergency stopping to enable rapid braking, then the stopping distance is reduced, but the propeller speed exceeds critical values causing windmilling effect and stability issues
Solution Approach 1:
The control system continuously monitors propeller speed and blade angle during the stopping maneuver, using feedback loops to adjust the blade angle in real-time. When propeller speed approaches critical values, the system automatically modifies the blade angle profile to prevent windmilling, ensuring both rapid deceleration and speed stability.
Solution Approach 2:
The system dynamically adjusts the blade angle profile based on real-time propeller speed measurements and operating conditions. Rather than using a fixed blade angle schedule, the control system modifies the blade angle trajectory during the stopping maneuver to optimize deceleration while preventing propeller speed from exceeding critical thresholds.
2Reliability
If regenerative converters are used to manage power flow back from the propeller, then the on-board power system stability is maintained, but the system complexity and cost increase significantly
Solution Approach 1:
The invention extracts and isolates the power management function from the main propulsion control system by implementing a dedicated control algorithm that specifically addresses power flow during stopping maneuvers. This separate control module manages the regenerative power flow without requiring complex hardware modifications to the entire propulsion system.
Solution Approach 2:
The control system acts as an intermediary between the propeller and the on-board power system during stopping maneuvers. By carefully controlling the blade angle and propeller speed profiles, the system mediates the power flow to prevent excessive reverse power that would require complex regenerative converters, while still maintaining power system stability.
3Loss of time
If the blade angle is rapidly reduced during stopping maneuver to maximize braking efficiency, then the stopping distance is minimized, but the propeller speed control becomes difficult to manage
Solution Approach 1:
The control system performs preliminary calculations and preparations before the stopping maneuver begins, pre-determining the optimal blade angle profile based on current operating conditions. This preliminary action allows the system to execute rapid deceleration while maintaining propeller speed control, as the control algorithm is already optimized for the specific operating point.
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
Enables rapid and efficient braking of watercraft with controllable pitch propellers, minimizing stopping distance and avoiding excessive propeller speeds, thus reducing the risk of damage and logistical complexities associated with regenerative converters.
Implementation Method 1
during emergency stopping, a power flow back from the propeller via the electric motor occurs, as the propeller acts as a turbine and the electric motor works as a generator
Implementation Method 2
the propeller acts as a turbine and the electric motor works as a generator
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for operating a drive system of a water vehicle during a stopping maneuver, wherein the drive system comprises at least one rotatable variable pitch propeller (1), which in each case comprises propeller blades having an adjustable blade angle (12), and which is driven by means of a motor (3), wherein the motor (3) can exercise a motor torque (15) on the variable pitch propeller (1), wherein a speed (13) of the water vehicle and a propeller torque (11) of the at least one variable pitch propeller (1) are determined. The invention further relates to a control, a water vehicle, a computer program and a computer program product for carrying out the method. In order to allow for a quick braking of the water vehicle, a characteristic line for the water vehicle is determined in advance, according to the invention, which line combines different start-speeds (17) of the water vehicle during the start of the stopping maneuvers with at least in each case one chronological sequence of the pitch propeller torque, such that during the stopping manoeuver the drive system operated according to the characteristic line results in a covered stopping path of the water vehicle which is a short as possible, and the propeller torque (11) does not exceed a torque value that can be predetermined and that is critical, wherein the drive system is operated during the stopping maneuver according to the characteristic line determined in advance.