Route-Based Battery Charge Control Under Thermal Limits
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Solution Overview
Problem
Existing methods for controlling battery temperature in hybrid vehicles, while limiting charging/discharging to prevent thermal degradation, often compromise the charge/discharge amount, thereby worsening fuel economy.
Innovation Solution
A charging/discharging control device that identifies excessive charging and discharging sections in a planned travel route and limits current values to ensure the battery state of charge reaches maximum and minimum levels, respectively, while controlling the output of the motor generator to manage battery temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charging/discharging is limited when battery temperature is high, then battery thermal degradation is prevented, but charge/discharge amount becomes insufficient
Solution Approach 1:
The system performs preliminary calculation of the state of charge change from the current position to the destination using route information and potential energy changes. Based on this preliminary assessment, it determines whether the battery can accumulate sufficient charge/discharge amount before temperature becomes excessive, and proactively adjusts motor generator output to ensure adequate charge/discharge while preventing thermal degradation.
Solution Approach 2:
The system dynamically adjusts the motor generator output based on real-time battery temperature, state of charge, and route characteristics. By continuously monitoring conditions and adapting the charging/discharging strategy, the system optimizes both thermal management and charge/discharge amount throughout the vehicle's operation.
2Temperature
If battery temperature is controlled by limiting motor generator output, then excessive temperature rise is prevented, but fuel economy deteriorates
Solution Approach 1:
The system calculates in advance the potential energy change along the planned route to estimate future battery charge/discharge opportunities. This allows the system to determine optimal moments for charging/discharging before temperature becomes excessive, ensuring both thermal control and fuel efficiency are maintained throughout the journey.
Solution Approach 2:
The system changes operational parameters including motor generator output limits, charge/discharge current constraints, and temperature thresholds based on real-time conditions and route characteristics. By dynamically adjusting these parameters, the system achieves effective temperature control while minimizing impact on fuel economy.
Data Source
AI summary
A charging/discharging control device includes a route information acquisition unit, a section identification unit that identifies an excessive discharging section and an excessive charging section, and a charging/discharging control unit that controls charging and discharging of a battery. The charging/discharging control unit limits a charge current value in the excessive charging section to a fixed first upper limit value. The state of charge reaches a maximum state of charge at an end point of the excessive charging section when the charge current value is maintained at the first upper limit value. The charging/discharging control unit limits a discharge current value in the excessive discharging section to a fixed second upper limit value. The state of charge reaches a minimum state of charge at an end point of the excessive discharging section when the discharge current value is maintained at the second upper limit value.