Power Window Controller Position Correction Voltage Drop
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Solution Overview
Problem
Existing power window systems face issues with accurately storing the position of a windowpane when the battery voltage drops below a predetermined level, leading to potential errors due to inertia, and require large-capacitance capacitors for data storage, increasing costs.
Innovation Solution
A power window system that includes a motor, drive mechanism, transducer, and controller, which generates signals to determine the windowpane's position and direction, outputs a stop signal when voltage drops, and corrects the stored position upon voltage restoration, allowing for accurate position correction without a large-capacitance capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the position of the windowpane is stored in memory after voltage drop, then the position data can be preserved, but inertia causes the motor to coast past the actual stop position creating position errors
Solution Approach 1:
The controller stores the position data in memory at the moment voltage drop is detected, before the motor actually stops. This preliminary storage action captures the intended position while the motor is still under electrical control, avoiding the inertia-induced overshoot that would occur if waiting for actual motor stop.
Solution Approach 2:
After voltage restoration, the controller reads the stored position data from memory and uses it as feedback to determine the correct stop position. The system compares the stored position with actual motor position and makes corrections to eliminate the inertia-induced position error.
2Reliability
If a large-capacitance capacitor is used to maintain voltage for memory writing during voltage drop, then data storage is ensured, but system cost and component size increase
Solution Approach 1:
The patent extracts the memory writing operation from the voltage-critical period. Instead of requiring continuous voltage support during the entire voltage drop event, the system performs memory writing only at the precise moment voltage drop is detected, using the still-available voltage at that instant. This eliminates the need for large-capacitance capacitors to sustain voltage over an extended period.
Solution Approach 2:
The position data is stored in memory immediately when voltage drop is detected, while the voltage is still sufficient for the writing operation. This preliminary storage action completes the memory write before voltage falls below the writing threshold, eliminating the need for backup power sources or large capacitors.
Data Source
AI summary
If a supply voltage for a motor drops below a predetermined level during movement of a windowpane, a controller of a power window system outputs a stop signal instructing the motor to stop rotating, and stores in a memory a first position and a motion direction of the windowpane derived from a first signal generated by a transducer (signal generator). The controller compares a second position of the windowpane derived from a second signal generated by the transducer when the supply voltage for the motor is restored to the predetermined level or higher with the first position of the windowpane stored in the memory. If the second position is different from the first position, the first position stored in the memory is corrected toward the motion direction by an amount corresponding to a difference between the first and second positions.