Ripple Cancellation Converter for LED Power Factor Correction
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Solution Overview
Problem
Conventional power supplies for LED lighting face challenges in achieving high power factor while minimizing low-frequency ripple, which causes visible flickering and reduces device lifespan, and often require two-stage conversion, increasing cost and size.
Innovation Solution
A circuit with a ripple cancellation converter that connects a second AC voltage or current ripple in series or parallel with the main output to cancel out the first AC ripple, providing substantially ripple-free DC power and high power factor using a buck converter, boost converter, or full bridge converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If critical conduction mode flyback converter is used for power factor correction, then power factor is improved, but output voltage ripple increases causing visible flickering
Solution Approach 1:
The patent segments the power conversion function into two independent stages: a power factor correction stage that handles only PF correction, and a separate DC-DC conversion stage that handles voltage regulation and isolation. This segmentation allows each stage to optimize for its specific function without compromising the other, eliminating the trade-off between power factor and output ripple.
2Object-generated harmful factors
If two-stage conversion is used to achieve high power factor and small ripple, then power factor and ripple performance are improved, but device complexity and size increase
Solution Approach 1:
The patent merges the power factor correction circuit and DC-DC conversion circuit into a single integrated converter architecture. The PFC circuit includes a first winding for PF correction and a second winding for DC-DC conversion, both sharing common magnetic components and control circuitry. This merging achieves the performance benefits of two-stage conversion while reducing device complexity, component count, and overall size.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively eliminates low-frequency ripple, preventing flickering and extending device lifespan while maintaining high power factor, reducing component count and cost, and allowing for compact, efficient power supplies.
Implementation Method 1
provides a second AC voltage ripple and is connected in series with the main output, such that the first AC voltage ripple is substantially cancelled
Data Source
AI summary
Provided are circuits and methods for use with a power supply that provides a main output including a main DC voltage having a first AC voltage ripple, or a main DC current having a first AC current ripple. A ripple cancellation converter provides a second AC voltage ripple connected in series with the main output, such that the first AC voltage ripple is substantially cancelled; or a second AC current ripple connected in parallel with the main output, such that the first AC current ripple is substantially cancelled. As a result, substantially ripple-free DC output power is provided.