Battery Management System with Isolated Current Injection
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Solution Overview
Problem
Existing battery management systems (BMS) face inefficiencies in charge equalization due to dissipation, incompatibility with cells of different chemistries, varying capacities, and operational histories, leading to unbalanced batteries during charging and discharging, especially when cells have different initial states of charge or leakage currents.
Innovation Solution
The implementation of a Dual Pole Single Throw (DPST) switch and Isolated Current Injection Supply (ICIS) with voltage and temperature monitoring circuits, allowing for isolated current injection to balance blocks by selectively activating DPST switches to redistribute charge among blocks, minimizing energy loss and maintaining balance during both charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional dissipation-based charge equalization is used, then charge balance is achieved, but energy loss increases
Solution Approach 1:
The patent introduces an isolated current injection supply as an intermediary device that transfers charge between battery blocks through isolated current injection. This mediator enables charge equalization without direct electrical connection between blocks, achieving balance while minimizing energy dissipation compared to traditional resistor-based dissipation methods.
Solution Approach 2:
The patent replaces the traditional passive dissipation mechanism (resistive heating) with an active isolated current injection system. This substitution transforms the charge equalization process from energy-dissipating to energy-efficient by using electronic control to redirect current flow, thereby reducing energy loss while maintaining balancing functionality.
2Adaptability or versatility
If cells of different chemistries are used to increase capacity flexibility, then system adaptability improves, but charge equalization complexity increases
Solution Approach 1:
The isolated current injection supply is designed as a universal system that can handle multiple battery chemistries (Lead-Acid, Li-ion, NiMH) through a single platform. The system achieves multi-functionality by monitoring voltage and temperature parameters that are common across different chemistries and applying appropriate current injection strategies, thereby managing chemistry diversity without proportionally increasing system complexity.
Solution Approach 2:
The system manages different battery chemistries by dynamically adjusting operational parameters such as voltage thresholds, temperature limits, and current injection rates. By changing these parameters based on detected battery chemistry and state, the system adapts to different cell types without requiring fundamentally different equalization mechanisms, thus controlling complexity while maintaining versatility.
3Quantity of substance
If blocks with different capacities are connected in series, then overall battery capacity increases, but charge balance difficulty increases
Solution Approach 1:
The system performs preliminary monitoring of block voltages and temperatures during charging, identifying blocks that are approaching full charge or have lower capacity before they become problematic. By detecting these conditions early and applying preventive current injection to undercharged or lower-capacity blocks, the system maintains charge balance proactively, enabling the use of different capacity blocks without compromising overall battery reliability.
4Productivity
If rapid charge equalization is implemented, then balancing speed increases, but energy dissipation increases
Solution Approach 1:
The isolated current injection system operates periodically, injecting current in controlled pulses or intervals rather than continuously. This periodic operation allows the system to achieve rapid balancing when needed while pausing to minimize energy dissipation, creating a rhythm of active balancing and idle states that optimizes both speed and energy efficiency compared to continuous high-power dissipation methods.
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 achieves minimal dissipation and rapid balancing of batteries with blocks of different chemistries and capacities, maintaining balance during both charging and discharging cycles, even with varying initial states of charge, thereby enhancing battery efficiency and longevity.
Implementation Method 1
isolated current injection supply (250) connected to blocks (20) of the battery (30)
Implementation Method 2
voltage monitoring circuit (210) connected to blocks (20) of the battery (30)
Implementation Method 3
temperature monitoring circuit (220) connected to blocks (20) of the battery (30)
Data Source
AI summary
A battery management system that monitors and controls the charging and discharging of a battery pack in the most versatile way at the block level with little dissipative loss but fast balancing is disclosed. The system has capability of using blocks of cells using different chemistry in the same battery pack. Such versatility makes it very useful for usage with erratic grid conditions, solar, wind and other natural energy sources for charging the battery.