Load Driver Ripple Current Cancellation
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Solution Overview
Problem
Single stage Power Factor Correction (PFC) + Flyback circuits for LED drivers achieve high efficiency and power factor but result in significant output ripple current, requiring large electrolytic capacitors that are cumbersome and costly, especially in compact applications.
Innovation Solution
A load driver with a DC-DC converter and an opposite phase ripple current generating circuit that combines two currents with opposite ripple phases to reduce output ripple current, using a smaller ordinary capacitor instead of large electrolytic capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single stage PFC + Flyback circuit is used, then the circuit complexity and cost are reduced, but the output ripple current increases significantly
Solution Approach 1:
The patent divides the current path into two separate windings (first and second windings) on the transformer, each carrying current with opposite ripple phases. This segmentation allows the ripple currents to cancel each other when combined, reducing the overall output ripple current while maintaining the single-stage circuit structure.
Solution Approach 2:
The patent generates a counterbalancing ripple current in the second winding that is equal in magnitude but opposite in phase to the ripple current in the first winding. This counterweight approach causes the ripple currents to cancel each other out, reducing the net ripple current without requiring additional filtering components.
2Object-generated harmful factors
If large electrolytic capacitors are used to reduce output ripple current, then the ripple current is reduced, but the device size and cost increase
Solution Approach 1:
Instead of using a single large capacitor, the patent segments the current path into two windings that produce opposite ripple phases. This segmentation allows ripple cancellation at the source, eliminating the need for large filtering capacitors and reducing overall device volume.
Solution Approach 2:
The patent converts the harmful ripple current into a beneficial feature by generating an opposite phase ripple current that cancels the original ripple. This transforms the ripple, which is normally a harmful effect requiring large capacitors to suppress, into a useful mechanism for ripple reduction without increasing component size.
3Object-generated harmful factors
If large electrolytic capacitors are used to reduce output ripple current, then the ripple current is reduced, but the manufacturing cost increases
Solution Approach 1:
The patent segments the transformer into two windings with opposite ripple phases, allowing ripple cancellation without requiring expensive large-capacity electrolytic capacitors. This approach reduces component costs and simplifies manufacturing while achieving the same ripple reduction effect.
Solution Approach 2:
The patent converts the harmful ripple current into a beneficial cancellation mechanism, eliminating the need for expensive large electrolytic capacitors. This approach reduces manufacturing costs by using standard components in a creative configuration rather than requiring expensive high-capacity capacitors.
Data Source
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AI summary
The present invention discloses a load driver and a method for reducing an output ripple current of a load driver. The load driver includes: a DC-DC converter, which has a first output and a second output; an opposite phase ripple current generating circuit, which is connected to the second output and configured to generate a second current, with a phase of a ripple current being opposite to a phase of a ripple current of a first current from the first output, wherein, the first current and the second current are combined into an output current to drive the load.