LED Power Converter Mode Switching for Low-Current Dimming
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Solution Overview
Problem
Conventional power converters for LED lighting face inefficiencies in controlling low output currents, particularly in dimming applications, due to limitations in pulse-skipping methods which result in visible dimming and mode transitional flicker, and require complex control or risk audible noise.
Innovation Solution
A power converter circuit with a controller that transitions between asynchronous and synchronous modes to control output current, using low-side switch circuitry and diodes to manage switching in each mode, allowing for better control of output current based on input settings, thereby improving dimming resolution and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse-skipping method is used to control low output current, then the power converter can operate at low current levels, but visible dimming and limited dimming resolution occur
Solution Approach 1:
The patent dynamically switches between two operating modes (asynchronous and synchronous) based on the output current level. At low current levels, the asynchronous mode is used to maintain continuous conduction and achieve fine dimming resolution. At higher current levels, the synchronous mode takes over. This dynamic adaptation allows the system to optimize dimming resolution across the entire operating range, preventing visible dimming steps while maintaining efficient low current operation.
2Use of energy by moving object
If conventional CCM buck controller is used with pulse-skipping, then low output current can be regulated, but mode transitional flicker and audible noise occur
Solution Approach 1:
The patent implements preliminary action by pre-configuring the asynchronous mode operation to maintain continuous conduction mode (CCM) at low current levels. By anticipating the transition needs and preparing the appropriate mode in advance, the system avoids abrupt mode changes that cause flicker and audible noise. The asynchronous mode is specifically designed to handle low current regulation smoothly, preventing the harmful effects associated with conventional mode transitions.
3Use of energy by moving object
If fractional burst or DCM methods are used to reduce output current, then control complexity or noise issues arise
Solution Approach 1:
The patent segments the operating range into two distinct regions handled by different modes: asynchronous mode for low current levels and synchronous mode for higher current levels. This segmentation allows each mode to be optimized independently for its specific operating range, avoiding the need for complex control algorithms like fractional burst or DCM. The clear division simplifies the overall control architecture while effectively managing output current across all levels.
Data Source
AI summary
An apparatus includes a controller (such as associated with a power converter). The controller is operative to receive input control settings. Based on the input control settings, the controller controls a magnitude of an output current generated by the power converter. The output current from the power converter powers light emitting hardware. The controller transitions between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current.