Brushless DC Motor Control for Occulting Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for controlling the stopping of motors in occultation devices, such as rolling shutters, often generate significant electromagnetic disturbances and fail to ensure instantaneous stopping due to inertia, leading to residual rotation and induced currents.
Innovation Solution
A method and device for controlling a brushless DC synchronous motor that detects motor stoppage using sensors or a predetermined time after signal interruption, allowing controlled connection of coil terminations only when the motor is confirmed stopped, thereby minimizing electromagnetic disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching device is activated during motor rotation to stop the motor, then the motor stopping speed is improved, but electromagnetic disturbances are generated
Solution Approach 1:
The control device determines motor stoppage based on rotation speed threshold detection before activating the switching device to connect coil terminations. This preliminary determination ensures the motor has sufficiently decelerated before the switching operation, preventing electromagnetic disturbances while achieving rapid stopping when needed.
2Loss of time
If the switching device is activated immediately upon stop command, then the response time is improved, but electromagnetic interference occurs due to back electromotive force
Solution Approach 1:
The control device continuously monitors motor rotation speed and uses this feedback to determine when the motor has decelerated sufficiently before activating the switching device. This feedback mechanism optimizes the timing of the switching operation, eliminating electromagnetic interference while maintaining rapid response to stop commands.
3Speed
If mechanical or magnetic brakes are used to stop the motor, then the stopping capability is improved, but the device complexity increases
Solution Approach 1:
The invention replaces mechanical or magnetic braking systems with an electrical control method using a switching device that connects coil terminations. This substitution eliminates the need for separate brake mechanisms while achieving effective motor stopping, thereby reducing device complexity while maintaining or improving stopping capability.
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
The solution effectively reduces electromagnetic disturbances and ensures reliable motor stopping without the need for additional sensors, lowering manufacturing costs and ensuring the motor stops without residual rotation or induced currents.
Implementation Method 1
the motor's inertia prevents it from stopping instantaneously
Implementation Method 2
during this phase, a back electromotive force is present, generating induced current through the motor windings and the switching device
Implementation Method 3
the sensors are Hall effect sensors and the first predetermined duration is equal to 70 milliseconds
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a method and a device for controlling the shutting down of a motor of an occulting device. The motor is a brushless direct current synchronous motor, controlled by a control device through a control circuit. The brushless direct current synchronous motor comprises coils, each coil comprising a first and a second termination, the first terminations are connected together and the second terminations are supplied with power to cause the rotation of the motor. The control device: - detects (E30) a shutdown command for the occulting device; - interrupts (E31) the supply of control signals to the control circuit; - determines (E33) the shutting down of the motor; - controls (E34) a switching device for connecting the second terminations of the coils when the motor is considered to be shut down.