LED String Regulation Modules for Power Factor Correction
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Solution Overview
Problem
Existing LED driving circuits, particularly AC-LEDs, face challenges in achieving good power factor and harmonic distortion due to stepwise currents, and are cumbersome for domestic applications with stringent constructional constraints.
Innovation Solution
An electronic circuit with multiple regulation modules that are sequentially activated based on a reference voltage derived from the rectified mains, ensuring current regulation is proportional to the voltage, thereby smoothing current flow through LED strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching converters are used to drive LED strings, then power factor and harmonic distortion performance is improved, but device complexity and constructional constraints increase
Solution Approach 1:
The driving circuit is divided into multiple regulation modules, each controlling a specific LED string. Each module independently regulates current based on the sinusoidal reference voltage, enabling distributed control that achieves good power factor without requiring a single complex switching converter.
Solution Approach 2:
The circuit dynamically activates or deactivates specific regulation modules based on the instantaneous value of the sinusoidal reference voltage. As the voltage increases, more modules are activated to maintain proportional current control, adapting the system complexity to the actual operating conditions.
2Device complexity
If AC-LED solutions with stepwise current control are used, then device complexity is reduced, but power factor and harmonic distortion performance deteriorate
Solution Approach 1:
The regulation modules are activated in a periodic sequence synchronized with the sinusoidal reference voltage. This periodic activation pattern ensures that current control follows the sinusoidal waveform, improving power factor while maintaining relatively simple circuit architecture compared to full switching converters.
3Use of energy by moving object
If more LED strings are connected in series to match increasing mains voltage, then power utilization is improved, but current regulation complexity increases
Solution Approach 1:
The LED strings are grouped into separate regulation modules, each handling a portion of the total voltage range. This segmentation allows independent control of each module, simplifying the regulation complexity while enabling efficient utilization of the full mains voltage range through sequential activation.
Data Source
AI summary
An electronic circuit drives a plurality of LED strings connected in series. The electronic circuit includes a regulation module corresponding to each LED string, with the regulation module connected to the cathode terminal of the corresponding LED string. Each regulation module is further coupled to receive a reference voltage in phase with a rectified a.c. voltage. The regulation modules execute in turn and in sequence a current-regulation phase as a function of a trend of the reference voltage. Each regulation module, when executing the current-regulation phase, functions to regulate the current that flows in the corresponding LED string and in any previous LED strings in the series connection so that the regulated current is proportional to the reference voltage.