Stochastic Battery Module Balancing for EMI-Stable Power Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery storage systems face challenges in balancing and load distribution between batteries, leading to voltage deviations and poor Electromagnetic Interference (EMI) characteristics, which hinder the delivery of AC waveforms for power grid connection and increase noise.
Innovation Solution
A battery storage system with stochastic or random balancing of batteries, utilizing a multilevel converter topology that includes switches to connect and isolate battery modules, employing availability values and random selection values to distribute load evenly and improve EMI performance, allowing for better voltage control and balancing of both battery modules and strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If batteries are activated based on state of health adaptation, then battery life is extended, but unbalancing occurs within charge/discharge cycles
Solution Approach 1:
The patent implements dynamic switching of battery modules where the activation sequence is randomly varied between charge and discharge cycles. This dynamic approach prevents fixed activation patterns that cause unbalancing, while still extending battery life through state-of-health-based management. The randomization introduces variability in which modules are activated during each cycle, ensuring more uniform wear and charge distribution across all modules.
2Stability of the object's composition
If individual cell controllers use random switching based on quality factor, then cell-level balancing is achieved, but significant voltage deviations occur and EMI characteristics deteriorate
Solution Approach 1:
The patent merges the control of multiple battery modules under a centralized controller that coordinates their switching actions. Instead of independent random switching at the cell level, the centralized controller manages the switching of entire modules in a coordinated manner. This combination approach maintains voltage control by ensuring that enough modules remain active to meet the required output voltage, while still achieving balancing through the randomized selection of which modules are activated.
Solution Approach 2:
The patent applies different switching strategies to different levels of the battery system. At the module level, random switching is used for balancing, while at the system level, voltage control is maintained through coordinated control. This local differentiation allows random switching to be used for balancing purposes without compromising overall voltage stability, as the centralized controller ensures minimum voltage requirements are met.
3Stability of the object's composition
If high-frequency random switching of individual cells is used, then balancing is achieved, but noise increases and EMI performance deteriorates
Solution Approach 1:
The patent segments the battery system into modules, each containing multiple cells that are controlled together as a unit. This segmentation allows the system to avoid high-frequency switching of individual cells, instead switching entire modules at lower frequencies. The modular structure enables balancing to be achieved through module-level randomization rather than cell-level switching, significantly reducing the high-frequency noise and EMI generated by rapid individual cell switching.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A battery storage system comprises at least one string of battery modules. Within the at least one string the battery modules are connected in series. Over multiple periods of time different combinations of battery modules are in a connected state with batteries connected while the remaining battery modules such that battery modules with a higher selection value have longer times in a connected state than battery modules with a lower selection value. The selection value of the at least one of the battery modules is a random value combined with an availability value of the battery module.