Active Charge Equilibrium System for Lithium Battery Packs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium battery pack series systems face inefficiencies in charging and discharging due to non-compliance between batteries, leading to energy loss, high heating, and safety risks, particularly with the use of relays which have short lifespans and high costs, and existing equilibrium methods are not suitable for large capacity packs or packs with significant voltage differences.
Innovation Solution
An active charge equilibrium system utilizing a multiplex module, control module, and equilibrium control modules with NMOS switches to manage voltage across lithium battery packs, converting voltage signals into digital signals, selecting cells with lower voltages for balanced charging through pulse width modulation, and employing NMOS transistors for efficient and safe energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relays are used to control battery charging equilibrium, then switching function is achieved, but service life is short and cost is high
Solution Approach 1:
The patent replaces mechanical relay switches with electronic NMOS transistor switches. The NMOS switch circuit includes a control end connected to the control module, a first end connected to the battery cell, and a second end connected to the charging circuit. This electronic substitution eliminates the mechanical contact wear issues of relays, significantly extending service life while reducing system cost and improving reliability.
2Reliability
If parallel resistors are used for energy consumed equilibrium method, then overcharging is prevented, but energy loss is high and heating is large
Solution Approach 1:
The patent changes the equilibrium method from energy-consuming resistor discharge to energy-transfer capacitor-based equilibrium. The control module detects battery voltage and uses NMOS switches to redirect charging current selectively to undercharged cells, avoiding the energy loss and heating problems of resistor-based methods while effectively preventing overcharging.
3Reliability
If multiple relays are used for battery selection and control, then charging equilibrium is achieved, but system complexity increases and safety risks increase
Solution Approach 1:
The patent merges multiple relay functions into a single integrated control module with NMOS switch arrays. The control module selectively activates specific NMOS switches based on real-time battery voltage detection, eliminating the need for multiple independent relays. This integration reduces system complexity, improves safety by eliminating relay contact sticking risks, and maintains effective charging equilibrium control.
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 system enhances charging efficiency, reduces energy loss, and extends the service life of lithium battery packs by using NMOS switches with lower power consumption and longer lifespan compared to relays, ensuring safer and more reliable operation across large capacity packs.
Implementation Method 1
an active charge equilibrium system utilizing a multiplex module, control module, and equilibrium control modules with NMOS switches to manage voltage across lithium battery packs
Implementation Method 2
enable the equilibrium control module corresponding to the cell with lower voltage to work through the control module for a pulse width modulator to adjust an output pulse width according to output current and voltage signals
Data Source
AI summary
An active charge equilibrium system for lithium battery pack consists a lithium battery pack composed of connecting multiple cells in series, including a multiplex module, control module and multiple equilibrium control module, which each segment of the cells are connected to the multiplex module in sequence, a voltage signal is converted into a digital signal via the control module to compare the voltages of the cells and select the cell with lower voltage. Further, the control module enables the equilibrium control module corresponding to the cell with the lower voltage to work. A pulse width modulator adjusts the output pulse width according to output current and voltage signal from a signal feedback module for controlling current and voltage to charge the cell. As the voltage of the cell reaches a constant current first and a constant voltage second, the control module turns off said equilibrium control module.