Dynamic Battery Power Balancing via Buck-Boost Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional battery management systems face inefficiencies in dynamically balancing power within battery packs during charging and discharging, leading to energy underutilization and premature battery deterioration due to cell imbalances, especially in large packs like those used in electric vehicles, where passive and active balancing methods incur power losses and prolong charging times.
Innovation Solution
A battery management system that dynamically balances power by using a control unit with converters to independently manage currents across blocks, allowing differential current flow from higher to lower state-of-charge cells, maximizing energy utilization through buck-boost converters and advanced algorithms for SOC and SOH estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive balancing is used to discharge higher SOC cells through power resistors, then cell voltage imbalance is reduced, but charging time is prolonged and energy is wasted as heat
Solution Approach 1:
A capacitor is introduced as an intermediary energy storage element between higher SOC and lower SOC cells. The capacitor temporarily stores excess energy from higher SOC cells and releases it to lower SOC cells, enabling direct energy transfer without dissipative resistors and avoiding prolongation of charging time
Solution Approach 2:
The system dynamically changes the balancing current parameter based on real-time SOC measurements. By adjusting the balancing current independently for each cell based on its SOC level, the system optimizes charging speed while maintaining voltage balance, preventing the time loss associated with fixed low-current passive balancing
2Temperature
If passive balancing is used with low bleeding current to control heat, then thermal management is improved, but charging time increases significantly
Solution Approach 1:
The capacitor serves as a thermal management intermediary by storing energy that would otherwise be dissipated as heat. Energy transfer through the capacitor occurs without resistive heating, enabling faster balancing currents without thermal consequences
Solution Approach 2:
The system replaces the thermal management approach of passive resistive dissipation with an electrostatic energy storage and transfer mechanism. This substitution eliminates the fundamental trade-off between heat control and charging speed by using a non-dissipative energy transfer path
3Reliability
If active balancing circuits are used to transfer energy between cells, then cell capacity utilization is improved, but power loss occurs during balancing operation
Solution Approach 1:
The capacitor acts as a lossless intermediary for energy transfer between cells. By storing energy temporarily in the capacitor's electric field and then releasing it to the target cell, the system achieves active balancing without the resistive power losses inherent in conventional active balancing circuits
Solution Approach 2:
The system utilizes the charging and discharging phases of the capacitor as distinct operational states. During the charging phase, the capacitor stores energy from higher SOC cells; during the discharging phase, it releases energy to lower SOC cells. This phase-based energy transfer eliminates continuous power loss
4Reliability
If conventional active balancing algorithms are used, then cell imbalance is corrected, but cell aging accelerates due to extra cycling
Solution Approach 1:
The system performs preliminary SOC estimation and identifies cells requiring balancing before initiating energy transfer. By pre-calculating which cells need charging and which need discharging based on SOC measurements, the system minimizes unnecessary cycling of already-balanced cells, thereby reducing accelerated aging
Solution Approach 2:
The system continuously monitors cell voltages and SOC levels, providing real-time feedback to adjust balancing operations. This feedback mechanism ensures that energy transfer stops precisely when cells are balanced, preventing over-cycling and the associated accelerated aging that occurs with conventional open-loop balancing algorithms
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 approach significantly reduces energy waste, accelerates charging, and extends battery life by minimizing unnecessary cycling, while allowing the use of lower-cost mismatched cells, thus enhancing overall battery pack performance and reducing manufacturing costs.
Implementation Method 1
The control unit includes one or more converters connected together in one of a series configuration or a parallel configuration. The control unit dynamically balances the power in the battery pack by controlling a differential current, using the plurality of converters, for flowing the differential current from a first block from among the one or more blocks associated with a higher SOC to a second block from among the one or more blocks associated with a lower SOC
Implementation Method 2
allowing differential current flow from higher to lower state-of-charge cells, maximizing energy utilization through buck-boost converters and advanced algorithms for SOC and SOH estimation
Data Source
AI summary
A system for dynamically balancing power in a battery pack during charging and discharging includes a battery pack, a control unit, and a load unit. The battery pack includes one or more modules. Each module includes one or more bricks. Each brick includes one or more blocks connected either in a series configuration or in a parallel configuration. Each block includes one or more cells. The control unit is connected with the battery pack across each of the blocks for processing power from each of the blocks irrespective of a power mismatch between the blocks. The control unit dynamically balances the power in the battery pack by controlling a differential current from a block with higher state of charge (SOC) to a block of lower SOC, using one or more converters and thereby maximizing available energy of the battery pack during charging and discharging.