Hybrid Battery SOC Calculation Threshold Control
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Solution Overview
Problem
Existing hybrid vehicle systems calculate vehicle state of charge (SOC) in a way that prioritizes electric travel over hybrid travel, leading to premature switching from charge depleting (CD) mode to charge sustaining (CS) mode, reducing electric travel distance due to excessive consideration of the minimum battery unit SOC, resulting in inefficient power management.
Innovation Solution
An electronic control device calculates a vehicle SOC by averaging the maximum and minimum unit SOCs, adjusting the calculation based on a threshold value to mitigate the effect of the minimum unit SOC, allowing for a higher SOC value when above the threshold and a lower value when below, thereby delaying the switch to CS mode and increasing electric travel distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vehicle SOC is calculated by considering the minimum unit SOC at a lower limit value, then over-discharge of battery units is prevented, but the vehicle SOC is calculated at a lower value than necessary, causing premature switching from CD mode to CS mode and reducing electric travel distance
Solution Approach 1:
The patent changes the calculation parameters of vehicle SOC by introducing a threshold value (set lower than the center value between upper and lower limits) and dynamically adjusting the calculation method based on whether the average unit SOC is above or below this threshold. When average unit SOC exceeds the threshold, the patent calculates vehicle SOC at a higher value than average unit SOC, effectively raising the parameter to extend electric travel distance. When average unit SOC falls below the threshold, it calculates vehicle SOC at a lower value to maintain safety margins and prevent over-discharge.
2Reliability
If the effect of minimum unit SOC on vehicle SOC is set to be excessively large, then over-discharge is prevented, but the vehicle SOC falls to the predetermined value earlier than necessary, leading to premature mode switching
Solution Approach 1:
The patent applies dynamics by making the calculation weight of minimum unit SOC variable rather than fixed. It dynamically adjusts the influence of minimum unit SOC on vehicle SOC calculation based on the relationship between average unit SOC and the threshold value. When average unit SOC is high, the minimum unit SOC has less influence, allowing longer electric travel. When average unit SOC drops below the threshold, the minimum unit SOC's influence increases to ensure safety, creating a dynamic adaptation mechanism that optimizes both battery protection and travel duration.
3Reliability
If the vehicle SOC is calculated at a lower value to ensure battery safety, then the CD mode is switched to CS mode earlier, but this results in reduced electric travel distance and inefficient power management
Solution Approach 1:
The patent segments the vehicle SOC calculation into different regimes based on the threshold value comparison. It divides the calculation approach into two segments: one for when average unit SOC exceeds the threshold (prioritizing travel distance by calculating vehicle SOC higher than average unit SOC) and another for when average unit SOC is below the threshold (prioritizing safety by calculating vehicle SOC at a lower value). This segmentation allows the system to optimize for different objectives at different stages of battery discharge.
Data Source
AI summary
A battery system includes an electricity storage device including a plurality of battery units. The electronic control device is configured to switch a travel mode of the vehicle between a CD mode and a CS mode. The electronic control device is configured to calculate a vehicle state of charge at a higher value than an average state of charge when the average state of charge is higher than a threshold value, and calculate the vehicle state of charge at a lower value than the average state of charge when the average state of charge is lower than the threshold value. The threshold value is set at a lower value than a center value between an upper limit value and a lower limit value of the vehicle state of charge.