Dimmable LED Power Supply PWM Frequency Selection for Flicker and Noise
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Solution Overview
Problem
Existing PWM dimming technologies for LED lamps face challenges in adjusting brightness without flicker and noise, particularly in environments requiring high camera shooting effects, where the PWM pulse frequency affects flicker and noise levels, limiting the ability to adjust brightness effectively.
Innovation Solution
A method for selecting PWM dimming frequency in LED power supplies using a control module to detect shift element signals, adjust PWM pulse frequency based on environmental conditions, and control MOS tube switches to optimize brightness, allowing user selection through interactive interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PWM pulse frequency is increased to reduce flicker effect for camera shooting, then flicker effect is reduced, but high-pitched noises are produced and dimming grayscale range is reduced
Solution Approach 1:
The patent implements dynamic PWM frequency adjustment based on operating conditions. The control module automatically selects from multiple preset frequencies (1kHz, 4kHz, 20kHz) or allows manual selection to optimize between flicker reduction and noise generation, enabling the system to adapt to different usage scenarios rather than operating at a fixed frequency
Solution Approach 2:
The patent changes the PWM frequency parameter dynamically based on the operating state. By providing multiple frequency options and automatic frequency selection based on detected conditions, the system adjusts this critical parameter to resolve the contradiction between reducing flicker and avoiding high-pitched noises
2Object-affected harmful factors
If PWM pulse frequency is increased to reduce flicker effect, then flicker effect is reduced, but dimming grayscale range is reduced
Solution Approach 1:
The system dynamically switches between different PWM frequencies based on the required dimming performance and flicker reduction needs. This allows the system to achieve both broad dimming grayscale range and low flicker effect by selecting appropriate frequencies for different operating conditions
Solution Approach 2:
The patent segments the PWM frequency operation into multiple discrete frequency levels (1kHz, 4kHz, 20kHz). This segmentation allows the system to optimize for different requirements: lower frequencies for broad dimming range and higher frequencies for reduced flicker, rather than using a single fixed frequency
3Adaptability or versatility
If PWM pulse frequency is decreased to broaden dimming grayscale range, then dimming effect is smooth and low brightness is achieved, but flicker phenomenon occurs
Solution Approach 1:
The control module dynamically adjusts the PWM frequency based on the desired dimming level and environmental conditions. When low brightness is required, the system can select lower frequencies for smooth dimming, while automatically switching to higher frequencies when flicker becomes problematic, thus resolving the contradiction dynamically
4Device complexity
If fixed PWM frequency is used, then system is simple, but cannot adapt to different environmental conditions and usage scenarios
Solution Approach 1:
The patent introduces dynamic frequency selection capability that allows the system to adapt to different environmental conditions and usage scenarios. The control module can automatically detect conditions and select appropriate frequencies, or provide user interfaces for manual selection, significantly improving adaptability while adding only moderate system complexity
Solution Approach 2:
The system is designed to perform multiple functions with a single framework by supporting multiple PWM frequencies and adaptation mechanisms. This universal design allows the same hardware to handle various scenarios including camera shooting, general illumination, and low-light conditions without requiring separate systems for each application
Data Source
AI summary
The present invention discloses a method of selecting a PWM dimming frequency for a dimmable LED power supply. After a main power drive is powered on, a main control module checks a shift element signal status of a four-shift switching module. Based on the main control module, a dimming PWM pulse frequency currently outputted by the power supply is determined according to the shift element signal status, a sample signal of a dimming signal processing circuit is collected to obtain a sample signal, a PWM drive signal is determined according to the dimming PWM pulse frequency and sample signal, and a switch status of a power MOS tube is controlled according to the PWM drive signal to adjust a lamp brightness. The invention allows user to freely select or set the dimming PWM pulse frequency of the dimmable power supply according to the environmental conditions of the use.