Rail Battery SOC Control Using Run-Out Prediction
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Solution Overview
Problem
Existing methods for managing the storage battery system in battery-powered electric railcars are inadequate in predicting the charging amount necessary for vehicle travel and in preventing battery deterioration, particularly due to the lack of consideration for meteorological information and battery deterioration state.
Innovation Solution
A storage battery system that includes a running-out-of-electricity occurrence prediction unit and an SOC control condition determination unit, which utilize storage battery information, meteorological information, and vehicle operation information to predict the occurrence of running out of electricity and determine optimal SOC control conditions to prevent battery deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage battery is used at high SOC to prevent running out of electricity, then the charging amount necessary for travel is secured, but the deterioration of the storage battery progresses
Solution Approach 1:
The system performs preliminary prediction of running out of electricity occurrence timing and magnitude of charging amount deficiency before actual operation. Based on this prediction, the target SOC is determined in advance, allowing the battery to be charged to appropriate levels only when necessary, rather than constantly maintaining high SOC. This preliminary action prevents unnecessary high SOC exposure while ensuring sufficient charging when running out of electricity is predicted.
Solution Approach 2:
The target SOC is made dynamic rather than fixed. The system adjusts the target SOC based on predicted running out of electricity occurrence timing and charging amount deficiency. When running out of electricity is predicted, the target SOC is raised to ensure sufficient charging; when not predicted, the target SOC is lowered to minimize deterioration. This dynamic adjustment optimizes the balance between preventing running out of electricity and reducing battery deterioration.
2Reliability
If the target SOC is increased to ensure sufficient charging amount, then running out of electricity is prevented, but the storage battery deteriorates faster
Solution Approach 1:
The system uses feedback from prediction results to adjust the target SOC. The prediction unit analyzes storage battery information, meteorological information, and vehicle operation information to predict running out of electricity occurrence. This prediction feedback directly influences the determination of target SOC, creating a closed-loop control system that adjusts charging targets based on actual operational needs rather than using a fixed high SOC target.
Solution Approach 2:
The system changes the target SOC parameter dynamically based on prediction results. Instead of maintaining a constantly high target SOC, the system adjusts this parameter upward only when running out of electricity is predicted and downward when it is not predicted. This parameter change strategy ensures charging sufficiency only when necessary while minimizing deterioration during normal operation.
3Duration of action of moving object
If the storage battery is constantly charged to high SOC, then the charging amount is sufficient for long periods, but the internal resistance increases and power output decreases
Solution Approach 1:
The system implements periodic assessment of running out of electricity risk through prediction, rather than continuous maintenance of high SOC. The target SOC is adjusted periodically based on prediction results, creating a rhythm of high SOC only when necessary and lower SOC during safe periods. This periodic action pattern maintains sufficient charging duration while minimizing the cumulative time spent at high SOC levels that cause internal resistance increase.
Data Source
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AI summary
The purpose of the present invention is to provide a technique that makes it possible to use a storage battery stably for a long time while preventing running out of electricity and appropriately keeping a train schedule. In order to achieve this purpose, the storage battery system according to the present invention comprises: a running-out-of-electricity occurrence prediction unit that predicts, at a time point until the starting time of a rail vehicle, the occurrence of running out of electricity on the basis of storage battery information, meteorological information, and vehicle operation information; and an SOC control condition determination unit that determines the SOC control condition of a storage battery on the basis of the prediction result of the running-out-of-electricity occurrence prediction unit. The SOC control condition determination unit also controls the SOC at the starting time and the upper limit SOC of the storage battery.