Electric Marine Propulsion Output Limiting for Battery Range Control
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Solution Overview
Problem
Electric marine propulsion systems face challenges in managing battery range and reducing user anxiety about running out of power, as users are concerned about maintaining sufficient battery power to reach their destination or shore, especially since they cannot easily exit the vessel or access help if stranded.
Innovation Solution
A control system that determines an output limit based on user-set time and battery charge level, automatically limiting motor torque, RPM, current, power, vessel speed, or helm demand to prevent battery depletion, ensuring the marine vessel can operate for the specified time without recharging, and alerts the user when demand exceeds the limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor operates at high power output to reduce travel time, then productivity is improved, but the battery charge level depletes faster reducing the duration of action
Solution Approach 1:
The system dynamically adjusts the output limit based on real-time battery charge level and user-set time parameters. The controller continuously monitors battery state and modifies motor power limits accordingly, transitioning from static power management to dynamic adaptation. This resolves the contradiction by allowing high power when battery is abundant while automatically reducing power as battery depletes, optimizing both productivity and duration.
Solution Approach 2:
The system implements feedback control by continuously monitoring battery charge level and using this information to adjust the motor output limit. The controller receives feedback about battery state and automatically modifies power delivery to ensure the vessel can operate for the user-set time. This closed-loop feedback mechanism resolves the contradiction by balancing power output with remaining battery capacity in real-time.
2Duration of action of moving object
If the system automatically limits motor output to conserve battery power, then the duration of action is improved, but the vessel speed and productivity decrease
Solution Approach 1:
The system performs preliminary calculation of the output limit based on user-set time and current battery charge level before operation begins. The controller pre-determines the maximum power output that will allow the vessel to operate for the specified duration, then maintains this limit throughout operation. This preliminary action resolves the contradiction by establishing appropriate power constraints in advance that balance duration requirements with acceptable productivity.
Solution Approach 2:
The system changes the motor output parameter (power limit) based on the relationship between battery charge level and desired operational time. By adjusting this key parameter dynamically, the system optimizes the balance between duration and productivity. The controller modifies power delivery parameters to ensure the vessel operates for the required time while maintaining reasonable speed and performance.
3Reliability
If the system provides real-time monitoring and automatic control to prevent battery depletion, then reliability is improved, but the device complexity increases
Solution Approach 1:
The control system provides self-service by automatically monitoring battery charge level and adjusting motor output limits without requiring user intervention. The system serves itself by making real-time decisions about power management based on battery state and user-set time parameters. This automation improves reliability while managing complexity through intelligent self-control rather than complex manual systems.
Solution Approach 2:
The controller performs multiple functions: it monitors battery charge level, calculates appropriate output limits based on user-set time, controls motor power delivery, and provides user feedback. By consolidating these functions into a single multi-functional control unit, the system achieves high reliability in power management while avoiding the complexity that would result from separate dedicated components for each function.
Data Source
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AI summary
A method of controlling an electric marine propulsion system (2) to propel a marine vessel (1) includes receiving a user-set time (81), determining a time remaining (85) based on the user-set time (81), and identifying a battery charge level (86) of a power storage system (16) on the marine vessel (1). A required battery power (89) is then determined based on the time remaining (85) and the battery charge level (86), and then an output limit (96) is determined based on the required battery power (89) to enable propelling the marine vessel (1) for the user-set time (81) without recharging the power storage system (16). The propulsion system (2) is automatically controlled so as not to exceed the output limit (96).