Rail Vehicle Storage Branch Charging by Relative State of Charge
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Solution Overview
Problem
Existing rail vehicle energy storage systems with parallel-connected branches face challenges in optimizing the service life due to uneven loading of energy storage branches with varying energy absorption capacities, leading to reduced resilience and lifespan.
Innovation Solution
A method where charging and discharging are managed by distributing energy based on branch-specific energy absorption capacities, ensuring all branches are charged or discharged to the same relative state of charge or discharge, calculated using specific formulas to maintain an average state and avoid deep discharging, thereby balancing the load across branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If charging energy is distributed equally among parallel-connected energy storage branches, then the charging process is simple to control, but branches with reduced energy absorption capacity due to aging are overloaded, reducing overall service life
Solution Approach 1:
The patent applies local quality by distributing charging energy differently to each energy storage branch based on its individual state of health and energy absorption capacity. Instead of uniform charging, each branch receives a customized charging amount proportional to its remaining capacity, preventing overloading of degraded branches while fully utilizing healthy ones.
Solution Approach 2:
The patent changes the charging parameter distribution by calculating and applying branch-specific charging energy amounts based on measured state of health parameters. The control system dynamically adjusts charging current or voltage per branch according to real-time parameter readings, optimizing both simplicity and reliability.
2Device complexity
If all energy storage branches are charged to the same absolute state of charge, then charging management is straightforward, but weaker branches with reduced capacity are subjected to excessive stress, accelerating their degradation
Solution Approach 1:
The patent implements local quality by setting different target state of charge levels for each energy storage branch according to its individual capacity. Healthier branches are charged to higher state of charge levels while degraded branches are charged to lower levels, customizing the charging regime to local branch conditions.
Solution Approach 2:
The patent applies partial action by charging each branch to a proportionally appropriate level rather than uniformly to maximum capacity. Weaker branches receive partial charging relative to their reduced capacity, avoiding the excessive stress that would result from full charging, while stronger branches receive full or near-full charging.
3Device complexity
If energy storage branches with varying capacities are operated in parallel without differentiation, then the system structure is simple, but uneven loading causes weaker branches to fail prematurely, reducing overall system reliability
Solution Approach 1:
The patent applies local quality by implementing branch-specific control parameters and charging strategies tailored to each energy storage branch's individual characteristics. The control system monitors and adjusts each branch independently based on its state of health, capacity, and performance metrics.
Solution Approach 2:
The patent implements dynamics by making the charging and discharging parameters adaptive and time-varying. The control system continuously monitors branch conditions and dynamically adjusts operating parameters to optimize performance and extend service life as branches age and their capacities change over time.
Data Source
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AI summary
The invention relates to a method for operating a storage arrangement of a rail vehicle comprising at least two electrically parallel connected energy storage branches. According to the invention, when charging the storage arrangement with charging energy, the distribution of the charging energy to the energy storage branches is carried out depending on their individual energy storage capacity. The at least two energy storage branches are each charged to the same relative state-of-charge setpoint, wherein the relative state-of-charge setpoint indicates the energy that the respective energy storage branch, relative to its individual maximum storable capacity, is to store after charging. The relative state-of-charge setpoint is calculated according to SoCsetpoint = SoCm + (dSoC/2), where SoCsetpoint denotes the state-of-charge setpoint, dSoC a relative change in state of charge, and SoCm an average state of charge.