Hybrid Motor Torque Map Switching for Battery Temperature Control
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Solution Overview
Problem
Existing motor control devices for hybrid automobiles fail to effectively balance fuel economy and battery temperature management, particularly on long uphill roads where battery temperature easily reaches discharge limits.
Innovation Solution
A motor control device that selectively uses two torque maps based on battery temperature, switching between a first map for low temperatures and a second map with a smaller maximum torque for temperatures above a switch temperature but below the limit start temperature, to optimize motor torque and balance fuel economy and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If motor torque is limited when battery temperature reaches discharge limit temperature, then battery temperature control is improved, but fuel economy deteriorates
Solution Approach 1:
The patent segments the battery temperature range into multiple regions (first temperature region below first threshold, second temperature region between first and second thresholds, third temperature region above second threshold) and applies different torque control strategies to each region. This allows optimized torque limitation that prevents excessive temperature rise while maintaining fuel economy by avoiding unnecessary torque restrictions in moderate temperature ranges.
Solution Approach 2:
The patent dynamically adjusts motor torque based on real-time battery temperature conditions by switching between different torque maps (first torque map, second torque map, third torque map) corresponding to different temperature regions. This dynamic adaptation enables the system to optimize the balance between temperature control and fuel economy according to actual operating conditions rather than applying fixed torque limitations.
2Temperature
If motor output is limited to curb excessive battery temperature rise, then battery temperature control is improved, but power output deteriorates
Solution Approach 1:
The patent changes the torque parameter dynamically based on battery temperature by selecting different torque maps (first, second, or third torque map) that define different torque characteristics for different temperature regions. This allows the system to maintain appropriate power output for driving performance while preventing excessive temperature rise through parameter adaptation rather than simple power limitation.
Data Source
AI summary
A motor control device includes an acquisition unit and a torque control unit that controls, by selectively using one of a first map and a second map, a motor torque defined in correspondence with a requested torque and an engine rotation speed in each of the first map and the second map. The torque control unit controls the motor torque using the first map when the battery temperature is less than a switch temperature lower than a limit start temperature at which the motor torque is limited, and controls the motor torque using the second map when the battery temperature is greater than or equal to the switch temperature and less than the limit start temperature. The second map includes a larger assist region than the first map. The assist region of the second map defines a smaller maximum torque than the assist region of the first map.