DC-DC Battery Module Balancing for Uneven State of Charge
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Solution Overview
Problem
Battery packs in consumer automobiles face challenges in fully utilizing electrical power due to differences in state-of-charge among battery modules, caused by variations in storage capacities resulting from differences in size, age, and chemistry.
Innovation Solution
A rechargeable energy storage system utilizing DC-to-DC converters and controllers to actively balance the state-of-charge among battery assemblies by converting and regulating power flows, allowing for independent utilization of available energies in each battery assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery modules are connected in series to form battery packs, then the total energy storage capacity increases, but some battery modules reach discharged state earlier due to capacity differences, preventing full utilization of power in non-discharged modules
Solution Approach 1:
The battery pack is divided into multiple battery modules, each with its own DC-to-DC converter and control circuitry. This segmentation allows independent management of each module's charge-discharge process, enabling the system to continue drawing power from non-discharged modules even when some modules reach their discharge limit, thus resolving the power utilization efficiency problem while maintaining high total capacity
Solution Approach 2:
DC-to-DC converters are introduced as intermediary devices between individual battery modules and the load. These converters act as mediators that can independently regulate power flow from each module, allowing the system to aggregate power from multiple modules with different states of charge without being constrained by the weakest module's capacity
2Adaptability or versatility
If battery modules have different storage capacities due to size, age, and chemistry variations, then the battery pack can accommodate diverse module characteristics, but the different states-of-charge among modules prevent full utilization of available power
Solution Approach 1:
Each battery module is equipped with its own DC-to-DC converter and control system, allowing localized optimization of charge-discharge parameters according to each module's specific characteristics (size, age, chemistry). This local quality approach enables the system to accommodate diverse module characteristics while maximizing the contribution of each module to the total available power
Solution Approach 2:
The control system dynamically adjusts the operating parameters of each DC-to-DC converter based on real-time monitoring of module states-of-charge, capacity, and condition. This dynamic adaptation allows the system to continuously optimize power extraction from modules with varying characteristics, ensuring maximum available power utilization despite heterogeneity in module properties
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 system effectively balances the state-of-charge among battery assemblies, maximizing the range of vehicles by ensuring that all battery modules contribute their available energy efficiently during discharge and recharge cycles.
Implementation Method 1
The first DC-to-DC converter is operational to: receive a first battery discharge power at the two first local nodes; convert the first battery discharge power to a pack discharge power that is presented at the two first inter-assembly nodes while in a discharge mode
Data Source
AI summary
A rechargeable energy storage system includes a DC-to-DC converter operational to: receive a battery discharge power at two first local nodes; and convert the battery discharge power to a pack discharge power at two first inter-assembly nodes while in a discharge mode in response to a control signal. The DC-to-DC converter is further operational to: receive a pack charge power at the two first inter-assembly nodes; and convert the pack charge power to a battery charge power at the two first local nodes while in a charge mode. A first battery assembly has a first state-of-charge. A second battery assembly has a second state-of-charge, and operates in series with the first battery assembly. The controller is operational to generate the control signal that varies the DC-to-DC converter to balance the first state-of-charge with the second state-of-charge while in the discharge mode.