EV Controller Power Limit Logic for SOC-Driven Stop
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Solution Overview
Problem
Existing electrically-driven vehicle systems inaccurately determine power deficiency, leading to erroneous conclusions that the vehicle can continue traveling when the power storage device is low, resulting in potential power depletion.
Innovation Solution
Implementing a controller that estimates the state of charge (SOC) of the power storage device, calculates an output power upper limit value, and stops the vehicle when the detected output power is lower than this value, especially when the SOC is low and the voltage reaches a lower limit, thereby preventing unnecessary travel and power depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the output power upper limit value is calculated using the estimated SOC, then the vehicle can operate with extended range, but erroneous determination of power deficiency occurs when SOC is low
Solution Approach 1:
The system continuously monitors the actual voltage of the power storage device and compares it with the lower limit voltage. When the voltage reaches the lower limit during discharge and SOC is low, the system provides feedback to recalculate the output power upper limit value based on actual power output, preventing erroneous determination of power deficiency and ensuring reliable operation until the end of discharge.
2Productivity
If the vehicle continues operation when SOC is low, then productivity is maintained, but power depletion occurs due to erroneous power deficiency determination
Solution Approach 1:
The system performs preliminary detection of the power storage device voltage and compares it with the lower limit voltage before allowing continued operation. When the voltage reaches the lower limit during discharge and SOC is low, the system proactively recalculates the output power upper limit value to prevent power depletion, ensuring the vehicle stops at the appropriate time rather than continuing operation.
3Reliability
If the output power upper limit value is decreased when SOC is low, then power deficiency is prevented, but the vehicle must stop prematurely
Solution Approach 1:
The system dynamically adjusts the output power upper limit value based on real-time conditions. When the voltage reaches the lower limit during discharge and SOC is low, the system calculates the upper limit value based on actual power output rather than using a fixed decreased value. This dynamic adjustment allows the vehicle to operate at maximum possible power until the end of discharge, maximizing productivity while preventing power deficiency.
Data Source
AI summary
An electrically-driven vehicle includes a power storage device that stores power to be supplied to a motor, and a controller that controls output of the power storage device. The controller estimates a SOC of the power storage device. The controller detects output power of the power storage device and calculates an output power upper limit value of the power storage device by using the SOC when a voltage of the power storage device reaches a lower limit voltage during discharge of the power storage device. The controller stops the electrically-driven vehicle in the case where the detected output power is lower than the output power upper limit value.