Bleeder Control for Phase-Cut Dimmers Using Timer-Based Edge Detection
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Solution Overview
Problem
Current phase-cut dimmer control methods require high MCU operation time for timely voltage sampling, leading to inefficiencies, thermal dissipation issues, and inaccurate phase-cut angle detection, especially with trailing edge dimmers, which cannot turn on the bleeder in advance, causing flickering and dimming inaccuracies.
Innovation Solution
A method involving a bleeder control system that uses timers to delay and advance the turning off and on of the bleeder based on detection voltage comparisons with a preset reference voltage, allowing for efficient and accurate control of phase-cut dimmers by detecting waveform edges and determining the current reference period of the input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the MCU samples the detection voltage timely with a high sampling rate to control the bleeder, then the bleeder control accuracy is improved, but the MCU operation time increases and more operation time is needed
Solution Approach 1:
The patent applies preliminary action by detecting the waveform edges (rising edge and falling edge) in advance and using timers to pre-calculate the turn-on and turn-off times of the bleeder. The MCU determines the current reference period of the input voltage and calculates the timing durations before the actual switching occurs, thereby reducing the need for continuous high-rate sampling during operation.
Solution Approach 2:
The patent introduces timers as intermediary components between the voltage detection and the bleeder control. The timers (first timer and second timer) mediate the control process by holding the calculated timing durations and triggering the bleeder switching at the precise moments, eliminating the need for the MCU to continuously sample and make real-time decisions.
2Speed
If the MCU continuously monitors and controls the bleeder with high sampling rate, then the control responsiveness is improved, but circuit losses increase and thermal dissipation becomes serious
Solution Approach 1:
The patent implements periodic action by using timers to control the bleeder switching at specific periodic intervals based on the detected waveform edges. Instead of continuous monitoring, the system performs discrete switching actions at predetermined times calculated from the waveform detection, reducing the operational duration of the bleeder and thereby minimizing energy losses and thermal dissipation.
3Device complexity
If the bleeder is controlled by timely voltage detection without advance timing, then the control simplicity is maintained, but phase-cut angle detection accuracy decreases causing flickering
Solution Approach 1:
The patent applies preliminary action by calculating and storing the turn-on and turn-off times of the bleeder in advance based on the detected waveform edges and the current reference period. The first timer is started at the falling edge and the second timer at the rising edge, with pre-calculated timing durations that ensure accurate phase-cut angle detection without requiring complex real-time control logic.
4Measurement precision
If the sampling rate is increased to accurately control the bleeder, then the control precision is improved, but the MCU operation burden increases
Solution Approach 1:
The patent introduces timers as intermediary components that handle the time-critical control functions. The timers capture the waveform edges and automatically trigger the bleeder switching at the precise moments without requiring the MCU to continuously sample and process data at high rates, thereby maintaining control precision while significantly reducing the MCU's operational burden.
Solution Approach 2:
The MCU performs preliminary calculations of the timing durations based on the detected waveform edges and current reference period before the actual switching occurs. This pre-calculation approach allows the system to achieve high control precision without requiring continuous high-rate sampling during operation, thus improving MCU operation efficiency.
Data Source
AI summary
The invention discloses a method for controlling a bleeder connected to a phase-cut dimmer and a circuit connected to a phase-cut dimmer. The method includes detecting an input voltage of the bleeder to obtain a detection voltage, and comparing the detection voltage and a preset reference voltage, wherein during a first time period, the detection voltage is less than the preset reference voltage, a start point of the first time period is a first moment, and an end point of the first time period is a second moment; delaying a first preset duration on the basis of the second moment to turn off the bleeder; and advancing a second preset duration on the basis of the first moment to turn on the bleeder.