Marine Propulsion Battery Control for Power Imbalance Limits
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Solution Overview
Problem
Electric marine propulsion systems with multiple batteries experience power imbalances leading to overdraw from batteries with lower power limits, causing overheating, degradation, and reduced battery health.
Innovation Solution
A control system identifies active batteries based on charge levels and determines a system power limit based on the minimum power limit of these batteries, ensuring the electric motor's power draw does not exceed this limit to prevent overtaxing any battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple batteries are used to increase power capacity, then the power supply capability is improved, but power imbalances cause overdraw from batteries with lower power limits leading to overheating and degradation
Solution Approach 1:
The control system continuously monitors the state of charge and power limits of each battery in the multi-battery system. Based on this feedback, the controller dynamically adjusts the power distribution to each battery, ensuring that no single battery is overdrawn beyond its power limit. This feedback mechanism prevents power imbalances that would otherwise cause overheating and degradation, thereby maintaining battery health while utilizing multiple batteries for increased power capacity.
Solution Approach 2:
The system dynamically changes operating parameters including the power draw limits assigned to each battery based on their state of charge, temperature, and health status. By adjusting these parameters in real-time, the control system optimizes power distribution across the multi-battery system, preventing any single battery from being overloaded while maximizing the total power output capability of the system.
2Speed
If power draw is increased to improve propulsion performance, then the vessel speed is improved, but batteries with lower power limits become overloaded and overheat
Solution Approach 1:
The control system dynamically adjusts the power draw from each battery based on real-time conditions including propulsion demands and battery thermal states. When high speed is required, the system distributes the power demand across multiple batteries in a manner that prevents any single battery from exceeding its thermal or power limits. This dynamic adjustment allows the system to achieve high vessel speeds while maintaining battery temperatures within safe operating ranges.
3Power
If all batteries are used simultaneously to maximize power output, then the available power is improved, but power imbalances cause some batteries to be overtaxed beyond their power limits
Solution Approach 1:
The control system applies different power draw characteristics to each individual battery based on its specific state of charge, power limit, and health status. Rather than treating all batteries uniformly, the system tailors the power extraction from each battery to its local conditions, ensuring that no battery is overtaxed beyond its capabilities. This localized control approach allows the system to maximize total available power while preventing power overdraw from any single battery.
Data Source
AI summary
An electric marine propulsion system configured to propel a marine vessel includes a power storage system comprising a plurality of batteries and at least one electric motor powered by the power storage system and configured to rotate a propulsor to propel the marine vessel. A control system is configured to identify a charge level for each of the plurality of batteries and determine which of the plurality of batteries are active batteries based at least in part on the charge level on each of the plurality of batteries. A minimum power limit is then identified for the active batteries and a system power limit is determined based on the minimum power limit and the number of active batteries. The at least one electric motor is then controlled based on the system power limit such that the system power limit is not exceeded.