SPB-PWM Pulse Bridging for Flicker-Free Phase-Shift Dimming
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Solution Overview
Problem
Pulse width modulation (PWM) in LED dimming applications experiences flicker during phase shift operations due to temporary decreases in duty cycle, affecting overall performance and causing undesirable effects in connected load devices.
Innovation Solution
The implementation of scaled phase bridging pulse width modulation (SPB-PWM) method, which compensates for temporary duty cycle decreases by inserting one or more pulses into the period of time occupied by a phase difference in the PWM signal, maintaining a consistent average voltage/power to the load device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase shifting is implemented to reduce peak currents and improve performance, then noise and EMI are reduced, but flicker occurs during phase shift operations
Solution Approach 1:
The patent applies preliminary action by detecting phase changes before they complete and proactively inserting compensatory pulses to prevent duty cycle drops. The PWM signal generator monitors phase transitions and prepares compensation pulses in advance, ensuring continuous duty cycle maintenance without allowing flicker to occur during phase shifts.
Solution Approach 2:
The patent implements feedback by continuously monitoring the PWM signal for phase changes and using this information to dynamically insert compensatory pulses. The system detects when a phase change occurs and automatically adjusts the PWM signal by inserting pulses to maintain the duty cycle, creating a closed-loop control mechanism that eliminates flicker while preserving the benefits of phase shifting.
2Adaptability or versatility
If phase changes are made in real-time during dimming, then dynamic control is achieved, but temporary duty cycle decreases cause flicker
Solution Approach 1:
The system performs preliminary detection of phase changes and prepares compensatory pulses before the duty cycle drop occurs. By anticipating the phase transition and having compensation pulses ready, the system maintains dynamic control while preventing flicker through proactive intervention.
Solution Approach 2:
The real-time monitoring and automatic pulse insertion creates a feedback loop that enables dynamic phase control without flicker. The system continuously adapts to phase changes and automatically corrects duty cycle drops, maintaining both adaptability and visual stability.
3Measurement precision
If PWM is used for LED dimming, then precise control is achieved, but phase shift operations cause visible flicker
Solution Approach 1:
The patent uses feedback to detect phase changes in the PWM signal and automatically inserts compensatory pulses to maintain the duty cycle. This closed-loop approach preserves the precise control capabilities of PWM while eliminating the flicker that occurs during phase transitions, as the system continuously monitors and corrects duty cycle variations.
Solution Approach 2:
By detecting phase changes early and inserting compensation pulses before the duty cycle drop becomes visible, the system maintains precise control over the LED dimming while preventing flicker. The preliminary detection and proactive compensation preserve PWM's precision benefits without the harmful side effects.
Data Source
AI summary
In an aspect, a method and system are provided. In an aspect, the method includes generating, by a pulse width modulation (PWM) signal generator, a PWM signal. The method further includes detecting, by the PWM signal generator, a phase change of the PWM signal from a lower value to a higher value or from the higher value to the lower value. The method also includes compensating, by the PWM signal generator, for a temporary decrease to a duty cycle of the PWM signal caused by the phase change by inserting one or more pulses into a period of time of the PWM signal occupied by the phase difference caused by a phase change of the PWM signal.