Motor Current Control for Smooth Window Deceleration
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Solution Overview
Problem
Existing methods for moving a movable element, such as a window pane, into a block position often result in perceivable delays and disturbing noise due to abrupt deceleration and mechanical stress, especially when interacting with window seals.
Innovation Solution
A method involving pulse-width modulation of the motor supply voltage to gradually reduce the motor current to zero over a preset time period, using a decreasing pulse duty ratio, to smoothly decelerate the element into a block position, thereby reducing mechanical stress and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the motor power is reduced to a minimal power level to decelerate the window pane before reaching a block position, then the window pane can be moved into the block position smoothly, but the deceleration process requires a relatively long time interval that makes the braking action perceivable by the user
Solution Approach 1:
The patent applies periodic action by using pulse-width modulation (PWM) to switch the motor supply voltage between on and off states at a high frequency. This creates a periodic control pattern where the motor receives intermittent power pulses rather than continuous or abrupt power reduction. The periodic switching allows the motor current to be reduced gradually through the PWM duty cycle adjustment while maintaining a perception of continuous operation to the user, thus shortening the perceivable deceleration time while still achieving smooth stopping.
2Loss of time
If the motor power is abruptly reduced to zero when the window pane reaches a block position, then the response time is minimized, but disturbing noise and mechanical stress occur due to the abrupt deceleration
Solution Approach 1:
Instead of abrupt power cutoff, the patent uses periodic PWM switching to gradually reduce motor power. The motor supply voltage is switched periodically with a duty cycle that decreases over time, allowing the motor to coast to a stop through the periodic pulses rather than sudden cessation. This periodic approach maintains smoother mechanical operation and reduces impact noise while achieving quick response.
Solution Approach 2:
The patent applies beforehand cushioning by initiating the PWM-based gradual power reduction process before the window pane actually reaches the block position. The control system detects the approaching block position and starts the periodic duty cycle reduction in advance, cushioning the mechanical system against abrupt stops. This preparatory gradual deceleration prevents mechanical shock and noise when the pane reaches the limit stop.
3Object-affected harmful factors
If the supply voltage is continuously reduced to zero over a time period using pulse-width modulation, then mechanical stress and noise are significantly reduced, but the control complexity increases
Solution Approach 1:
The patent replaces complex mechanical braking mechanisms with electronic PWM control of the motor supply voltage. Instead of using mechanical friction brakes or complex mechanical deceleration devices, the invention uses electronic switching and pulse-width modulation to control motor power. This substitution of electronic control for mechanical braking simplifies the overall system while achieving smooth deceleration and reducing mechanical stress.
Solution Approach 2:
The PWM control method uses periodic voltage switching to achieve gradual power reduction. By modulating the duty cycle of periodic voltage pulses, the system controls motor current and torque in a graduated manner without requiring complex analog control circuits. This periodic electronic control approach manages the complexity through standardized switching techniques while achieving the desired smooth deceleration effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures smooth deceleration and significant noise reduction by gradually reducing motor power, alleviating mechanical stress and minimizing noise during the movement into a block position, enhancing the operational reliability and user experience.
Implementation Method 1
an electric motor configured to drive the element with motor power in order to move the element along the path
Implementation Method 2
the motor current generated by the motor is continuously reduced over a time period to zero
Data Source
AI summary
A method for moving a movable element into a block position includes providing a supply voltage to an electric motor associated with the movable element for the motor to generate a motor current and drive the element with motor power dependent on the motor current in order to move the element along a path. Upon the element being moved into a block position of the path, the supply voltage provided to the motor is controlled such that the motor current generated by the motor is continuously reduced over a time period to zero. For instance, the supply voltage is pulse-width modulated at a decreasing pulse duty ratio over the time period such that the motor current generated by the motor is continuously reduced over the time period to zero.