Battery Cluster Current Equalization to Prevent Loop Currents
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Solution Overview
Problem
In battery systems where multiple clusters are connected in parallel, differences in state of charge (SOC) and current between clusters lead to loop currents, resulting in wasted capacity and instability, as the cluster with high voltage charges the one with low voltage, causing premature cut-off and reduced utilization of battery capacity.
Innovation Solution
A control method and device that utilize loop currents by adjusting the current of battery clusters with DCDC converters to equalize SOC, preventing premature cut-off and extending power supply time by controlling currents and voltages, thereby maximizing capacity utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple battery clusters are connected in parallel to increase capacity, then the total capacity of the battery system is improved, but loop currents are generated between clusters with different SOC and voltage, causing capacity waste and instability
Solution Approach 1:
The control device continuously monitors the SOC and current of each battery cluster, and dynamically adjusts the DCDC converter output based on real-time feedback. When a cluster's current approaches the threshold, the controller modulates the DCDC converter to equalize currents across all clusters, preventing loop current formation while maximizing capacity utilization.
Solution Approach 2:
The system changes the operating parameters (current output) of each battery cluster through DCDC converters to achieve equalization. By dynamically adjusting the current parameter of clusters with higher SOC to match clusters with lower SOC, the system eliminates voltage differences that cause loop currents, thereby improving capacity utilization.
2Duration of action of moving object
If battery clusters operate until reaching cut-off current threshold, then the power supply duration is extended, but loop currents cause premature cut-off and reduce the usable capacity of the system
Solution Approach 1:
The control device performs preliminary equalization of currents between battery clusters before any cluster reaches the cut-off threshold. By proactively adjusting DCDC converter outputs to maintain equal currents across all clusters, the system prevents premature cut-off caused by loop currents, thereby extending power supply duration without sacrificing usable capacity.
3Quantity of substance
If the current of a battery cluster is controlled to reach a preset value, then the capacity utilization is improved, but additional control complexity is introduced
Solution Approach 1:
The control device serves multiple functions: it monitors SOC and current of all battery clusters, controls DCDC converters for current equalization, prevents loop current formation, and extends power supply duration. By consolidating these functions into a single control system, the patent achieves high capacity utilization without proportionally increasing control complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively utilizes remaining capacity at the end of charge/discharge cycles by equalizing SOC between clusters, prolonging power supply and improving overall capacity utilization of the battery system.
Implementation Method 1
sending first information to a first direct current-direct current converter connected in series with the first battery cluster, the first information being used to instruct controlling the current of the first battery cluster to reach a first preset current
Data Source
AI summary
Disclosed are a control method for a battery system, device, and a battery system, the method comprising: determining that a state of charge (SOC) and a current of a first battery cluster in N battery clusters meet a first preset condition, the first preset condition including: the SOC of the first battery cluster is greater than a first threshold and the current of the first battery cluster is greater than a second threshold or less than a third threshold, wherein the second threshold is set according to a maximum permissible current of the first battery cluster, and the third threshold is set according to an average current of the N battery clusters; and sending first information to a first DCDC converter connected in series with the first battery cluster., the first information being used to instruct controlling the current of the first battery cluster to reach a first preset current.