EV Battery Discharge Control for Stable Distance to Empty
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Solution Overview
Problem
Existing electric vehicle battery discharge control techniques that aim to reduce battery deterioration by limiting the state of charge (SOC) within a predetermined range can lead to misrecognition of issues by drivers due to decreased distance to empty, causing discomfort even when no fault exists.
Innovation Solution
An electric vehicle control apparatus that includes a discharge control section to manage battery discharge when the SOC is within a range prone to deterioration, a distance-to-empty calculation section, and a running factor correction section to stabilize the calculated distance to empty, thereby reducing changes and driver misperception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharge control is performed to reduce battery deterioration by limiting SOC within a predetermined range, then battery durability is improved, but the distance to empty decreases causing driver misrecognition
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the running factor based on the SOC range. When SOC is within the predetermined deterioration-prone range, the system changes the running factor to compensate for the expected distance reduction, thereby maintaining accurate distance-to-empty display while still performing discharge control to protect battery durability.
Solution Approach 2:
The system uses feedback by continuously monitoring the SOC and comparing it against the predetermined range, then adjusting the running factor accordingly. This closed-loop control ensures that the distance to empty calculation remains accurate even when discharge control is active, preventing driver misrecognition while maintaining battery health.
2Duration of action of stationary object
If discharge control is performed when key is turned off to prevent battery deterioration, then battery lifespan is improved, but driver comfort deteriorates due to perceived vehicle issues
Solution Approach 1:
The patent changes the running factor parameter in response to discharge control actions. When the key is turned off and discharge control is activated to extend battery lifespan, the system simultaneously adjusts the running factor to maintain consistent distance to empty display, thereby preventing driver discomfort or misrecognition of vehicle issues.
3Reliability
If SOC is maintained within predetermined range to reduce deterioration, then battery reliability is improved, but the calculated distance to empty becomes unstable
Solution Approach 1:
The system applies parameter changes by adjusting the running factor based on the current SOC position within the predetermined range. This dynamic parameter adjustment compensates for SOC fluctuations, maintaining stable distance to empty calculations while the battery operates within the reliability-optimized SOC range.
Solution Approach 2:
The running factor acts as an intermediary between the SOC and the distance to empty calculation. When SOC varies within the predetermined range for battery reliability, the running factor mediates these changes to produce stable distance to empty values, preventing instability in the displayed range information.
Data Source
AI summary
This control device for an electric vehicle is provided with: a discharge control unit which, when the electric vehicle has been turned off, if the SOC of the battery is within a prescribed range in which the battery is prone to deteriorate, performs control for discharging the battery until the SOC has left the prescribed range; a travelable distance calculation unit which calculates the travelable distance of the electric vehicle using the SOC and a travel coefficient; and a travel coefficient correction unit which, before and after performing control for discharging the battery is performed by the discharge control unit, corrects the travel coefficient such that the travelable distance calculated by the travelable distance calculation unit is reduced.