Marine Lithium-Ion Battery Control Device for Over-Discharge Prevention
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Solution Overview
Problem
In marine vessels, there is a lack of effective control methods for lithium ion batteries, which are prone to over-discharge and over-charge, leading to reduced lifespan and performance, especially when used in hybrid propulsion systems.
Innovation Solution
A control device for a marine vessel's lithium ion battery that includes a controller to monitor and manage the battery's power storage amount, turning off a switch when the battery reaches a predetermined low level to prevent over-discharge and turning it back on when a chargeable condition is met to recover the battery's power storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lithium ion battery is continuously connected to the line to supply electric power, then the battery can continuously discharge to drive the motor, but the battery may undergo over-discharge which reduces its lifespan and performance
Solution Approach 1:
The control device performs preliminary assessment of the electric power balance on the line before reconnecting the battery. It calculates whether the generator can produce sufficient power to cover the motor and other loads, ensuring the battery will not immediately face another over-discharge risk upon reconnection
Solution Approach 2:
The control device continuously monitors the power storage amount of the battery and the electric power balance on the line. This feedback mechanism allows the system to dynamically adjust the switch state based on real-time conditions, preventing over-discharge while maximizing continuous discharge capability when safe
2Reliability
If the switch is turned off to prevent over-discharge, then the battery is protected from damage, but the battery cannot recover its power storage amount efficiently
Solution Approach 1:
The control device uses continuous feedback on the electric power balance to determine the optimal moment to reconnect the battery. It monitors whether the generator output exceeds the total load demand, and only when this condition is met does it close the switch, ensuring efficient power recovery while maintaining protection
Solution Approach 2:
The system dynamically adjusts the switch state based on real-time power balance conditions rather than using a fixed timing strategy. The battery connection is restored as soon as the power balance becomes positive, maximizing recovery efficiency while maintaining protective measures
3Power
If the battery operates outside the predetermined SOC range, then more electric power can be supplied to the motor, but the battery life and performance are reduced due to overcharge or over-discharge
Solution Approach 1:
The control device takes preliminary anti-action by preventing the battery from entering over-discharge states through proactive switch disconnection. By anticipating the over-discharge condition and disconnecting before it occurs, the system protects battery life while still allowing operation near the lower SOC limit to maximize power supply
Data Source
AI summary
A control device for a battery of a marine vessel recovers a power storage amount of a chargeable lithium ion battery while protecting the same. When an acquired power storage amount of the lithium ion battery becomes equal to or less than a first predetermined power storage amount, a switch to connect the lithium ion battery and a line or a load is turned off. While the switch is off, as an electric power balance on the line, a power inflow amount, a first power outflow amount, and a second power outflow amount are acquired. Based on the electric power balance acquired while the switch is off, whether a chargeable condition in which the lithium ion battery is chargeable is satisfied is determined. When the chargeable condition is satisfied, the switch is turned on.