Motor Temperature Control After Abnormal Power-Off
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Solution Overview
Problem
Conventional drive member control apparatuses for power window systems fail to accurately estimate motor temperature after abnormal power-off conditions, leading to potential motor burnout due to incorrect temperature settings.
Innovation Solution
A control unit that stores and updates estimated motor temperature during normal power cycles and restricts power supply when the estimated temperature reaches a predetermined threshold, ensuring the difference between the threshold and estimated temperature is minimized upon abnormal cycle termination, thereby preventing motor burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the estimated motor temperature is memorized at power OFF and estimated at power ON based on the memorized temperature, then the motor temperature estimation is simplified, but the temperature estimation accuracy deteriorates when abnormal power-off occurs
Solution Approach 1:
The control unit sets the estimated motor temperature to a predetermined value (higher than ambient temperature) in advance when abnormal power-off is detected, before the next power-on occurs. This preliminary action ensures that the temperature estimation starts from a safe baseline rather than an potentially inaccurate memorized value, preventing motor burnout while maintaining operational simplicity.
2Productivity
If the motor operates without temperature restriction, then the productivity is improved, but the motor reliability deteriorates due to potential burnout
Solution Approach 1:
The control unit continuously monitors the estimated motor temperature and compares it against the operation restriction threshold temperature. When the estimated temperature reaches or exceeds the threshold, the control unit restricts power supply to the motor. This feedback mechanism enables the motor to operate continuously at high productivity while automatically preventing burnout through temperature-based control.
3Reliability
If the power supply is restricted when estimated temperature reaches threshold, then the motor reliability is improved, but the operation time is reduced due to power restrictions
Solution Approach 1:
The control unit dynamically adjusts the operation restriction threshold temperature based on the estimated motor temperature history and operating conditions. By making the threshold adaptive rather than fixed, the system allows extended operation time when temperatures remain low while still providing protective restrictions when temperatures approach dangerous levels, thus balancing reliability with operational duration.
Data Source
AI summary
A drive member control apparatus is provided with a control unit that controls a motor for driving a drive member and restricts a power supply to the motor when an estimated motor temperature reaches an operation restriction threshold temperature. The control unit is configured to set, at power ON, when determined that a control is terminated abnormally in a previous cycle, a difference between the operation restriction threshold temperature and the estimated motor temperature to be less than a maximum value.