LED Lighting Circuit Oscillation Suppression via Dynamic Counting
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Solution Overview
Problem
Existing semiconductor light source lighting circuits face oscillation issues when digitized, particularly due to interactions between feedback control and switching operations in LED lighting systems, which can lead to instability and performance degradation.
Innovation Solution
A semiconductor light source lighting circuit is designed with a switching regulator and a control circuit that includes a current feedback control mechanism, where the counting cycle of a digital control value is synchronized with the ON/OFF cycle of the switching element to prevent oscillation, using separate oscillators for the drive and control circuits to maintain independent frequency control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control circuit is digitized to reduce circuit size and improve feedback control performance, then circuit size is reduced and control performance is improved, but oscillation may occur in the drive current due to interaction between counting operation and switching operation
Solution Approach 1:
The patent applies dynamics by making the counting cycle variable rather than fixed. The control value counting speed is dynamically adjusted based on the switching element's ON/OFF cycle, allowing the system to adapt to different operating conditions and prevent oscillation while maintaining digitized control benefits
Solution Approach 2:
The patent changes the parameter of counting cycle duration based on the switching cycle. By adjusting the counting cycle to be longer than the switching cycle during steady operation, the system prevents harmful interactions while maintaining digital control advantages
2Stability of the object's composition
If the counting cycle is made longer to suppress oscillation, then drive current stability is improved, but response speed to voltage changes may be reduced
Solution Approach 1:
The system dynamically adjusts the counting cycle duration based on operating conditions. During steady operation, the counting cycle is longer to suppress oscillation. During sudden voltage changes, the counting cycle is shortened to improve response speed, allowing the system to maintain both stability and responsiveness
Solution Approach 2:
The patent uses periodic switching of the counting cycle duration based on operating mode. The counting operation alternates between longer cycles (for stability) and shorter cycles (for response), synchronized with the switching element's operation to prevent oscillation while maintaining responsiveness
Data Source
AI summary
A semiconductor light source lighting circuit is provided with: a switching regulator that generates a drive current of a semiconductor light source using a switching element; and a control circuit that controls ON/OFF of the switching element. The control circuit is provided with: a comparator that compares the drive current and a target value; a counter that counts a digital value in a count direction determined by a comparison result of the comparator; a digital-analog converter that converts the digital value into an analog signal; and a drive circuit that controls the ON/OFF of the switching element based on the analog signal. The counter counts the digital value at a speed determined by an ON/OFF cycle of the switching element.