Shift Range Switchover Control Device Motor Temperature Estimation
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Solution Overview
Problem
Conventional shift range switchover control devices for vehicles fail to accurately estimate motor temperatures when the power supply is turned off, leading to improper heat protection and unnecessary battery discharge due to prolonged power supply to the ECU.
Innovation Solution
A shift range switchover control device with a temperature estimation part that calculates the restart-time temperature based on the final temperature stored during system stop time and the off period, using a non-volatile memory and soak timer to ensure accurate temperature estimation upon restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply to the ECU is continued after the ignition switch is turned off to perform initial driving control, then the motor temperature can be controlled, but the battery discharges unnecessarily when the motor has already cooled down
Solution Approach 1:
The system performs preliminary temperature estimation before restarting the ECU by calculating the motor temperature at the time of ignition switch turn-off and estimating the temperature at restart time based on the elapse time. This preliminary action allows the system to determine whether initial driving control is actually needed, avoiding unnecessary battery discharge while ensuring motor temperature control when required.
Solution Approach 2:
The system uses feedback by continuously monitoring the estimated motor temperature and comparing it with the permissible heat generation temperature. Based on this feedback, the ECU dynamically adjusts whether to perform initial driving control or to skip it, optimizing the balance between motor protection and energy conservation.
2Reliability
If the motor is prohibited from being driven when the estimated temperature reaches the permissible heat generation temperature, then the motor and ECU are protected from overheating, but the shift range cannot be switched over
Solution Approach 1:
The system implements periodic action by temporarily prohibiting motor driving when the estimated temperature reaches the permissible heat generation temperature, then allowing driving again after a predetermined period has elapsed. This periodic prohibition and permission cycle enables the motor and ECU to cool down while still permitting shift range switchover operations to resume after the cooling period.
3Device complexity
If the restart-time temperature is set to the product-mounting environment temperature, then the system is simplified, but the motor will not be protected properly when the ignition switch is turned on immediately after being turned off with high estimated temperature
Solution Approach 1:
The system performs preliminary temperature estimation at the moment the ignition switch is turned off, calculating both the final temperature (at turn-off time) and the restart-time temperature (estimated temperature when ECU restarts). This preliminary action ensures that even when the ignition switch is turned on immediately, the system has accurate temperature information to determine whether motor protection is needed, avoiding the need for complex real-time monitoring while maintaining reliability.
Data Source
AI summary
A shift range switchover control ECU controls a motor of an actuator provided to switch over a shift range of a vehicle and includes a temperature estimation part and a driving control part. The temperature estimation part estimates a temperature of the motor 11 based on a driving state of the motor. The driving control part controls driving of the motor and limits the driving of the motor when an estimated temperature exceeds a protection temperature. The temperature estimation part calculates, based on a final temperature indicating the estimated temperature of a system stop time, a restart-time temperature, which is the estimated temperature at time of turning on a starting switch of the vehicle again after turning off the starting switch, and a delay period, during which the temperature estimation part continues to calculate the estimated temperature after turning off of the starting switch. It is thus possible to properly estimate the temperature of the motor.