Multi-Pack Battery Charging with Pulse Balancing and Voltage Limits
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Solution Overview
Problem
In multi-pack battery systems for vehicles, it is challenging to charge all battery packs to the same state of charge due to differences in open circuit voltage and internal resistance, leading to slow charging or less energy storage than expected.
Innovation Solution
A method involving grouping battery packs by charge rates, using a sequence of charge and discharge pulses, and estimating relaxed discharge open circuit voltage to ensure all packs reach a predetermined operational voltage limit, allowing for faster and more efficient charging without violating critical voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional charging is used on multi-pack battery systems, then charging simplicity is maintained, but charging speed and energy storage efficiency deteriorate due to voltage differences between packs
Solution Approach 1:
The patent divides the battery system into multiple packs and further segments the charging process into distinct phases (constant current charging, constant voltage charging, and pulse charging). Each pack is charged independently according to its own state, allowing different charging strategies to be applied to different packs simultaneously, thereby resolving the contradiction between charging speed and system complexity.
Solution Approach 2:
The patent implements periodic pulse charging where alternating current is applied in pulses with specific duty cycles. During pulse charging, the system periodically switches between charging and discharging phases, which helps to equalize voltage differences between packs while maintaining overall charging progress. This periodic action enables faster charging without compromising voltage balance.
2Stability of the object's composition
If charging continues until all packs reach the same SOC, then voltage balance is achieved, but total charging time increases due to waiting for the slowest pack
Solution Approach 1:
The patent applies preliminary constant current charging to bring all packs closer to their target voltage before switching to constant voltage charging. This preliminary action reduces the time packs need to wait for voltage equalization, as packs are pre-charged to near-target levels and then finished individually. The system proactively manages voltage balance rather than reactively waiting for the slowest pack.
Solution Approach 2:
The patent allows different packs to have different charging states at different times, with each pack receiving charging current tailored to its specific voltage and SOC levels. Instead of forcing all packs to the same charging rate, the system applies local quality control where each pack's charging parameters are independently optimized, reducing overall charging time while maintaining acceptable voltage balance.
3Productivity
If higher charging voltages are applied to increase charging speed, then charging time decreases, but voltage limits are violated compromising battery health
Solution Approach 1:
The patent uses periodic pulse charging with alternating current applied in controlled pulses. During the charging phase of each pulse, higher voltages can be applied to increase charging speed, followed by a discharge phase that allows voltage to settle and prevents sustained overvoltage conditions. This periodic action enables faster charging while maintaining battery health through controlled voltage excursions.
Solution Approach 2:
The patent dynamically adjusts charging voltage and current based on real-time pack voltage and SOC measurements. The system transitions between charging phases (constant current to constant voltage to pulse charging) based on dynamic conditions, allowing higher voltages to be applied only when safe and necessary. This dynamic control enables faster charging while preventing voltage limit violations that would compromise battery health.
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
This method increases the energy content stored in the battery system while maintaining healthy voltage levels, potentially extending the battery system's lifetime and enabling faster charging.
Implementation Method 1
A charge pulse adds energy to the electrical energy storage pack whereas a discharge pulse withdraws energy from the electrical energy storage pack
Implementation Method 2
A charge pulse adds energy to the electrical energy storage pack whereas a discharge pulse withdraws energy from the electrical energy storage pack
Implementation Method 3
after a resting period, estimating with a relaxed voltage estimator, an at least partly relaxed discharge open circuit voltage of the one group from a voltage increase caused by the charging step
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present disclosure relates to a computer-implemented method and a system for charging an electrical energy storage system (2) comprising more than one electrical energy storage pack (14) connected to a traction voltage bus (16) of a vehicle.