Ripple Suppression Circuit for LED Lighting
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Solution Overview
Problem
Switching power supplies driving LED loads often experience ripple components in output signals, leading to flicker or stroboscopic effects, and existing solutions like electrolytic capacitors for power factor correction have limitations in efficiency and service life.
Innovation Solution
A ripple suppression circuit that includes a ripple voltage sampling circuit and a voltage regulation circuit, where the ripple reference voltage generated from the output voltage of a DC converter is used to control the voltage across a transistor coupled between the LED load and ground, effectively eliminating current ripples by maintaining a consistent voltage across the LED load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electrolytic capacitors are used for power factor correction, then power factor is improved, but service life is reduced
Solution Approach 1:
The patent replaces expensive, long-lived electrolytic capacitors with a simpler capacitorless PFC circuit that uses shorter-lived, cheaper components. The PFC is achieved through a combination of a PFC switch, PFC diode, and control circuitry that eliminates the need for large electrolytic capacitors, thereby improving service life while maintaining power factor correction.
Solution Approach 2:
The patent changes the operating parameters of the power supply by implementing a two-stage switching mechanism where the PFC switch operates at a different frequency and duty cycle than the main output switch. This parameter change allows for power factor correction without relying on electrolytic capacitors, thus extending service life while maintaining energy efficiency.
2Use of energy by moving object
If switching power supply is used to drive LED load, then power efficiency is improved, but ripple components cause flicker effects
Solution Approach 1:
The patent introduces an intermediary smoothing capacitor that acts as a mediator between the switching power supply output and the LED load. This capacitor filters out the ripple components generated by the switching operation, preventing them from reaching the LED load and causing flicker, while allowing the efficient switching operation to continue.
Solution Approach 2:
The patent employs periodic switching action with carefully controlled duty cycles for both the PFC switch and output switch. By synchronizing and controlling the timing of these periodic switching operations, the circuit achieves both power factor correction and ripple reduction, eliminating flicker while maintaining high power efficiency.
Data Source
AI summary
A ripple suppression circuit configured to suppress a current ripple provided to a load by a DC converter, can include: a ripple voltage sampling circuit coupled to output terminals of the DC converter, where the ripple voltage sampling circuit is configured to generate a ripple reference voltage that represents a ripple voltage of an output voltage of the DC converter; and a voltage regulation circuit coupled to the load and the ripple voltage sampling circuit, where the voltage regulation circuit is controllable by the ripple reference voltage such that a voltage across the voltage regulation circuit is consistent with the ripple voltage.