Battery String Phase Sharing for SOC Balancing Control
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Solution Overview
Problem
Existing battery systems in vehicles struggle to efficiently balance the state of charge (SOC) across multiple battery strings and modules, leading to uneven charging and discharging, which can reduce battery life and overall system efficiency.
Innovation Solution
A battery system with a switch control module that uses model predictive control (MPC) to determine the state of charges (SOCs) of battery strings, balance SOCs across modules, and selectively actuate switches to connect strings in series or parallel, optimizing phase durations to achieve balanced SOC distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery strings are connected in series or parallel using traditional control methods, then the battery system can operate, but the state of charge (SOC) distribution across strings becomes uneven, reducing battery life and system efficiency
Solution Approach 1:
The patent implements dynamic switching control where the connection configuration of battery strings (series/parallel/disconnected) changes continuously based on real-time SOC measurements. The switch control module adjusts the topology dynamically rather than using fixed connections, allowing the system to adapt to varying SOC conditions and achieve balanced charging/discharging across all strings.
Solution Approach 2:
The system employs feedback control by continuously monitoring the SOC of each battery string and using this information to determine switching actions. The switch control module receives SOC data, compares it against target values, and adjusts the connection configuration accordingly, creating a closed-loop control system that maintains balanced SOC distribution.
2Productivity
If traditional switching control is used to connect battery strings, then the system structure is simple, but the SOC balancing efficiency is poor leading to uneven charging and discharging
Solution Approach 1:
The battery system is divided into multiple independently controllable strings, each with its own switching control. The switch control module manages each string's connection state (series, parallel, or disconnected) separately based on individual SOC conditions, allowing granular control over charging/discharging processes to achieve efficient SOC balancing.
Solution Approach 2:
The system changes the electrical connection parameters (series/parallel configuration) of battery strings dynamically based on SOC conditions. By altering the connection topology rather than changing physical components, the system achieves efficient SOC balancing through parameter adjustment, maintaining relatively simple hardware while improving performance.
3Reliability
If battery modules operate without phase sharing, then the control logic is simpler, but the SOC balancing performance is suboptimal
Solution Approach 1:
The patent implements periodic phase-based control where battery strings go through cycles of connection and disconnection phases. During these periodic phases, strings are connected in series or parallel for controlled durations, allowing SOC balancing to occur in a structured, repeating pattern that improves system efficiency while maintaining manageable control logic.
Data Source
AI summary
A battery system includes: two battery modules, each including three strings of battery cells that are configured to, at different times be: connected in series and to a first positive terminal via first ones of switches; connected in parallel and to a second positive terminal via second ones of the switches; and disconnected from both of the first and second positive terminals; and a switch control module configured to: determine state of charges (SOCs) of the strings of battery cells, respectively; determine, using model predictive control, periods of phases, respectively, to balance SOCs of the battery modules; determine, using model predictive control, periods for the strings, respectively, including setting one of the periods for one of the strings to be included in at least two of the phases; and selectively actuate the switches based on the periods of the phases and the periods for the strings of battery cells.