Battery Pack SOC Equalization Using Sheath Heater Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Commercial electric vehicles, such as electric buses, face significant challenges with voltage and SOC unbalances among battery packs due to their higher energy and power requirements, leading to reduced driving distance and shortened battery lifespan, which existing balancing methods fail to adequately address.
Innovation Solution
A method involving a controller that acquires SOC information from state detectors, determines an average SOC value, identifies battery packs needing discharge for equalization, and operates sheath heaters connected to these packs as electric loads to discharge them, thereby equalizing the SOCs of battery packs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a serial and parallel combined connection method is used to mount a large number of batteries in commercial electric vehicles, then the energy and power requirements are met, but voltage and SOC unbalances among battery packs occur, reducing driving distance and battery lifespan
Solution Approach 1:
The system uses the vehicle's own heating system (heating device) to discharge battery packs with higher SOC, rather than external balancing equipment. The heating device converts electrical energy to thermal energy, creating a self-contained balancing mechanism that uses existing vehicle components.
Solution Approach 2:
The system changes the operational state of battery packs by controlling discharge through the heating device. By adjusting the heating power and duration, the SOC of specific battery packs is reduced to match the average SOC, achieving equalization through parameter control.
2Reliability
If passive discharge using resistance or active balance using external apparatus is used to balance battery packs, then SOC equalization is achieved, but device complexity increases and is not suitable for commercial electric vehicles with many battery packs
Solution Approach 1:
The heating device, which is already part of the vehicle's thermal management system, is given an additional function: serving as a discharge load for SOC equalization. This eliminates the need for separate balancing circuits or external balancing apparatus, reducing system complexity while maintaining equalization capability.
Solution Approach 2:
The patent combines the thermal management function and the SOC equalization function into a single system. The heating device simultaneously manages battery temperature and equalizes SOC across battery packs, merging two functions that were previously handled by separate systems.
3Quantity of substance
If more batteries are mounted to meet higher energy requirements, then energy capacity increases, but SOC unbalance becomes more serious, requiring more complex balancing solutions
Solution Approach 1:
The system extracts or identifies specific battery packs that have higher SOC than the average, and selectively applies discharge to these packs through the heating device. This targeted approach addresses unbalance in the subset of affected battery packs without requiring system-wide changes.
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 approach effectively balances the SOCs of battery packs, reducing voltage and SOC unbalances, thereby extending the driving range and lifespan of commercial electric vehicles while minimizing energy loss.
Implementation Method 1
operating a sheath heater connected to the at least one determined battery pack to discharge the at least one determined battery pack
Data Source
AI summary
A method for equalizing SOCs of battery packs in an electric vehicle, may include acquiring, by a controller, SOC information of the battery packs from battery pack state information acquired by state detectors under predetermined conditions of the electric vehicle, determining, by the controller, an average SOC value of the battery packs based on acquired SOC values of the respective battery packs, determining, by the controller, at least one battery pack required to be discharged for equalization of the SOCs of the battery packs among all the battery packs based on the SOC values of the respective battery packs and the determined average SOC value of the battery packs, and operating, by the controller, an electric load connected to the at least one determined battery pack required to be discharged to discharge the at least one determined battery pack required to be discharged.