Power Supply Switching Frequency Sync for Low Output Ripple

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Solution Overview

Problem

Output ripple current in LED drivers can cause flickering of LED light output, negatively affect LED life, and increase power dissipation, leading to higher junction temperatures and reduced lifespan.

Innovation Solution

A method and system that involve sensing the AC input voltage waveform, determining a correction factor for the switching frequency of the power supply, and applying this correction factor to synchronize the switching frequency with the AC input voltage waveform, thereby reducing output ripple current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a filter capacitor is used to reduce low frequency ripple, then output ripple current is reduced, but the capacitor becomes large and expensive

Engineering Contradiction:

Improveoutput ripple currentVSAvoidfilter capacitor size

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The patent changes the switching frequency parameter dynamically to reduce output ripple. By adjusting the switching frequency based on the ripple characteristics, the system achieves ripple reduction without requiring large filter capacitors. The control circuit modifies the switching frequency within a range to optimize ripple performance while maintaining compact capacitor sizes.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If a filter capacitor is used to reduce low frequency ripple, then output ripple current is reduced, but the cost increases

Engineering Contradiction:

Improveoutput ripple currentVSAvoidpower supply cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent employs dynamic switching frequency adjustment as a parameter change strategy to reduce ripple. This approach eliminates the need for expensive large-capacity filter capacitors, thereby reducing the overall power supply cost while maintaining effective ripple suppression. The control circuit implements frequency modulation to achieve cost-effective ripple reduction.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If switching frequency is increased to reduce ripple, then output ripple current is reduced, but power dissipation increases

Engineering Contradiction:

Improveoutput ripple currentVSAvoidpower dissipation

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent implements dynamic switching frequency adjustment rather than simply increasing frequency. The control circuit modifies the switching frequency within an optimized range to reduce ripple while balancing power dissipation. This parameter optimization approach achieves ripple suppression without excessive energy loss, unlike simple frequency increases.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic switching frequency modulation to adapt to different operating conditions. By making the switching frequency variable rather than fixed, the system can reduce ripple effectively while minimizing power dissipation. The dynamic adjustment allows the converter to optimize performance across varying load and input voltage conditions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12244220B2Low frequency output ripple cancelation for a power supply

Publication Date: 2025.03.04 ABL IP HLDG LLC

AI summary

A method for reducing current ripple at an output of a power supply includes sensing an alternating current (AC) input voltage waveform; determining a correction factor for a switching frequency of the power supply based on the sensed AC input voltage; and applying the correction factor to the switching frequency of the power supply to modify the power supply switching frequency. A modification of the switching frequency synchronizes the switching frequency of the power supply to the AC input voltage waveform.