Charge Balancing Control for Parallel Battery Backup Systems
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Solution Overview
Problem
Battery Backup Systems (BBSs) face inefficiencies and reliability issues due to differences in state-of-charge and capacity among parallel-connected battery packs, leading to shortened lifespan and over-charging/over-discharging problems, as existing charge balancing techniques are not efficient.
Innovation Solution
A battery backup system that performs charge balancing control by individually adjusting the power output of each battery unit through a control circuit, which measures bus voltage and current, and battery characteristics to produce personalized duty cycles for converters, ensuring balanced charge distribution among parallel-connected battery units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery packs are connected in parallel to provide high current and high power, then the power output capability is improved, but differences in capacity and state-of-charge among individual packs cause charge imbalance and reduce system reliability
Solution Approach 1:
The control system segments the parallel-connected battery packs into individually controllable units, measuring bus voltage and current along with battery characteristics for each pack. This segmentation enables independent duty cycle adjustment for each converter, allowing the system to maintain high power output while addressing charge imbalance at the individual pack level.
Solution Approach 2:
The patent applies local quality by producing personalized duty cycles for each converter based on individual battery pack characteristics. Each battery pack receives tailored control parameters that account for its specific capacity, state-of-charge, and performance characteristics, enabling balanced charge distribution while maintaining overall system power capability.
2Adaptability or versatility
If individual battery packs have different capacities and state-of-charge levels, then manufacturing flexibility and adaptability are improved, but charge/discharge rate diversity degrades overall system performance and shortens lifespan
Solution Approach 1:
The control system dynamically adjusts operating parameters by measuring battery characteristics and producing personalized duty cycles for each converter. This parameter adaptation allows the system to accommodate battery packs with different capacities and states of charge, optimizing charge/discharge rates for each pack to extend overall system lifespan while maintaining manufacturing flexibility.
Solution Approach 2:
The patent implements dynamic control by continuously measuring bus voltage, current, and battery characteristics, then adjusting duty cycles in real-time based on changing conditions. This dynamic adaptation enables the system to handle diverse battery pack characteristics and varying operational states, preventing over-charging and over-discharging that would otherwise shorten battery lifespan.
3Reliability
If traditional charge balancing techniques are used, then charge distribution is improved, but system efficiency is reduced due to lack of personalized control for each battery unit
Solution Approach 1:
The patent achieves both charge balance and high efficiency through local quality control by producing personalized duty cycles for each converter based on individual battery pack measurements. This localized control ensures that each pack is charged and discharged at optimal rates, maintaining charge balance while minimizing energy losses and maximizing system productivity.
Solution Approach 2:
The control system implements feedback by measuring bus voltage, current, and battery characteristics, then using this information to adjust personalized duty cycles for each converter. This closed-loop feedback mechanism ensures charge balance is maintained while optimizing system efficiency, as the control decisions are continuously refined based on actual battery pack performance.
Data Source
AI summary
According to one embodiment, a battery backup system includes an output terminal, one or more BBUs coupled in parallel to provide backup power to an external electronic device coupled to the output terminal, and a control circuit to control the power distribution from the BBUs. Each of the BBUs includes a battery pack having one or more battery cells and a converter to regulate and output power to the output terminal. The control circuit is configured to control a duty cycle for each of the BBUs, which when used to drive the BBU, adjusts power output in order to balance charges amongst the BBUs. The duty cycle of each BBU is determined based on an output voltage across the output terminal, an output current flowing through the output terminal, and characteristics of the battery pack of the BBU.