PHEV Battery Charge Sustain Window Adjustment for Cold Drivability
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Solution Overview
Problem
Plug-in hybrid electric vehicles (PHEVs) experience poor drivability due to low battery discharge limits when the battery is cold and has a low state-of-charge (SOC), leading to reduced propulsion performance and increased engine usage.
Innovation Solution
A method and system that dynamically adjusts the battery's state-of-charge (SOC) by charging it with the engine when discharge limits fall below a threshold, establishing a new charge sustain window at a higher SOC to increase discharge limits, and then transitions back to the original SOC range as the battery warms up, ensuring consistent drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the battery operates at low SOC to extend electric driving range, then the electric driving range is improved, but the discharge limit decreases leading to poor drivability
Solution Approach 1:
The patent implements dynamic adjustment of the charge sustain window based on battery temperature. When battery temperature is low, the system dynamically shifts the charge sustain window to a higher SOC range, allowing the battery to operate at higher SOC levels during cold conditions to maintain adequate discharge limits while still preserving electric driving range during warmer operation.
Solution Approach 2:
The system changes the operating parameters by adjusting the charge sustain window boundaries according to battery temperature conditions. This parameter change allows the battery to operate at different SOC levels depending on temperature, ensuring adequate discharge limits in cold conditions while maximizing electric range in warm conditions.
2Quantity of substance
If the battery is cold and has low SOC, then the battery weight and volume remain optimized, but the discharge limit becomes too low for adequate drivability
Solution Approach 1:
The system dynamically adjusts the charge sustain window to higher SOC levels when battery temperature is low, ensuring the battery operates at higher charge levels during cold conditions. This dynamic adjustment maintains adequate discharge limits without requiring physical changes to battery size or capacity.
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 enhances drivability by maintaining discharge limits above the threshold, even in cold conditions, by increasing the SOC during charge sustain mode and transitioning back to the original range as the battery warms, thereby improving powertrain performance and reducing engine assistance.
Implementation Method 1
A plug-in hybrid electric vehicle (PHEV) has a traction battery for supplying power for propulsion
Implementation Method 2
The PHEV also has an engine that can operate independently to propel the vehicle
Data Source
AI summary
Methods and systems for a vehicle such as a plug-in hybrid electric vehicle (PHEV) having a traction battery are for improving the drivability of the vehicle the battery has low discharge limits. The battery may have such low discharge limits due to the battery being cold and/or the battery state-of-charge (SOC) being low. In operation, upon the battery having a discharge limit lower than a threshold while the vehicle is operating in a charge sustain mode, the engine of the vehicle is used to charge the battery to increase the SOC of the battery such that the battery has a discharge limit greater than the threshold. The vehicle is operated in the charge sustain mode using the battery with the increased SOC.