Battery Controller for Selective Parameter Estimation
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Solution Overview
Problem
Existing methods for estimating battery capacity and internal resistance in large-scale electricity storage systems require suspension of operations for precise measurement, leading to reduced availability and decreased estimation precision when performed under operating conditions.
Innovation Solution
An electricity storage system with a battery controller that allows for test charging and discharging of selected batteries while maintaining system operation, using a selecting unit, SOC data obtaining unit, arithmetic determining unit, and distribution rate determining unit to calculate and distribute power values, enabling precise parameter estimation without system suspension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test charging and discharging is performed to obtain precise battery characteristic parameters, then measurement precision is improved, but system availability deteriorates due to operation suspension
Solution Approach 1:
The battery system is divided into multiple individual batteries, allowing selective testing of specific batteries while others continue to operate. The controller identifies and selects target batteries for characteristic parameter measurement, enabling parallel operation of tested and non-tested batteries, thus maintaining system availability while achieving precise measurements on selected units.
Solution Approach 2:
The system dynamically adjusts the charging and discharging states of individual batteries based on real-time operational requirements. The controller can flexibly switch between normal operation mode and test mode for selected batteries, optimizing the balance between measurement precision and system availability by making batteries available for testing when operational demand is low.
2Reliability
If estimation is performed under operated status, then system availability is maintained, but measurement precision deteriorates due to dependency on charging and discharging conditions
Solution Approach 1:
The system performs characteristic parameter measurements periodically or at scheduled intervals rather than continuously. The controller determines appropriate timing for test charging and discharging based on operational patterns, conducting measurements during periods when system demand is low or when natural load variations provide suitable test conditions, thus achieving precise measurements without compromising overall system availability.
Solution Approach 2:
The system utilizes its own operational characteristics and natural load variations to create test conditions. By monitoring real-time charging and discharging states, the controller identifies opportunities to perform measurements using existing operational fluctuations, eliminating the need for dedicated external test equipment or complete system shutdowns.
3Measurement precision
If current fluctuation is increased to estimate internal resistance, then measurement precision is improved, but system operation stability deteriorates
Solution Approach 1:
Current fluctuations for measurement purposes are applied locally to selected target batteries rather than to the entire battery system. The controller isolates specific batteries for testing and applies controlled current variations only to those units, leaving other batteries operating under normal stable conditions. This localized approach enables precise internal resistance measurement while maintaining overall system operational stability.
Data Source
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AI summary
An electricity storage system 10 includes a plurality of chargeable and dischargeable battery boards 3-1 to 3-30, a plurality of PCSs 2-1 to 2-30 connected to the respective battery boards, and charging and discharging the connected batteries, and a battery controller 1 distributing a charging and discharging power value of the entire system as an instruction value to each of the PCSs 2-1 to 2-30 at a constant cycle or at an arbitrary timing. The battery controller gives a charging and discharging instruction for a predefined test charging and discharging to the selected battery board, and distributes, to all the battery boards except the selected battery board, a value obtained by subtracting a charging and discharging power value for the test charging and discharging from a charging and discharging power value for the entire system.