Ceiling Fan BLDC Speed Control Using Switch Timing Signals
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Solution Overview
Problem
Ceiling fan users face inconvenience in adjusting rotational speed in dim environments due to the need to visually identify switch settings on a wall control switch, making it difficult to accurately control the fan's speed.
Innovation Solution
A brushless DC motor control system using a first switch, detection module, timer, processing module, and driving module to control rotational speed and direction through distinct electric potential duration intervals, allowing for convenient operation without visual reliance on switch settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a wall control switch with visual speed indicators is used, then the user can identify rotational speed settings, but the user cannot accurately control the fan speed in dim environments without light
Solution Approach 1:
The patent replaces the mechanical visual identification system with an electronic feedback system. Instead of relying on visual indicators on a mechanical switch, the system uses a sensor to detect the switch state, a microcontroller to process the signal duration, and a display to show the selected speed, thereby eliminating the need for visual identification of switch positions.
Solution Approach 2:
The patent implements feedback by displaying the selected rotational speed on a display unit after the sensor detects the switch state. This feedback loop allows the user to confirm the selected speed without needing to visually identify the switch position in advance, solving the problem of controlling the fan in dim environments.
2Device complexity
If a hand-pull switch is used for speed control, then the structure is simple, but the user must physically pull the switch multiple times for speed adjustment which is inconvenient
Solution Approach 1:
The patent transforms the static hand-pull switch into a dynamic system where the switch state is detected over time. The microcontroller measures the duration of the switch signal to determine the selected speed, allowing for more nuanced control while maintaining a simple physical switch interface.
Solution Approach 2:
The patent changes the control parameter from discrete switch positions to continuous signal duration. By measuring how long the switch is held in a position, the system can distinguish between different speed selections, providing finer control granularity without adding physical complexity to the switch itself.
3Device complexity
If the user must visually identify switch settings, then the control mechanism is simple, but the user experiences inconvenience and potential errors in dim environments
Solution Approach 1:
The patent introduces an intermediary sensor between the physical switch and the control system. The sensor detects the switch state and converts it into an electrical signal that the microcontroller can process, eliminating the need for direct visual identification by the user and improving selection accuracy.
Solution Approach 2:
The patent replaces the visual-mechanical identification process with an electronic detection and processing system. The sensor detects the switch state electronically, the microcontroller processes the signal duration precisely, and the display provides visual feedback, thereby improving measurement precision while adding electronic complexity.
Data Source
AI summary
A brushless DC motor control system for a ceiling fan is electrically connected to a brushless DC motor, and includes a first switch, a detection module, a timer, a processing module, and a driving module. The first switch sends a first switch signal to the detection module for detection. The detection module outputs an operating electric potential detection signal to the timer. The timer outputs an operating electric potential timing signal to the processing module, so that the processing module outputs a first control signal and a second control signal to the driving module for controlling the brushless DC motor to change the rotational speed and the rotational direction respectively, increasing the convenience of use.