Ripple Current Mode Power Factor Correction

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Solution Overview

Problem

Existing power factor correction methods face challenges in operating in continuous current mode without AC current sensing, leading to noise-prone systems or power wastage, and require AC line voltage or current monitoring, which complicates the design and increases costs due to noise coupling and component stress.

Innovation Solution

Ripple current mode control method that infers AC input current from two charge current samples, allowing high signal gain without power wastage and enabling continuous current mode operation without monitoring AC source voltage or current, with the controller potentially located remotely from noise-generating components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If discontinuous current mode control is used, then implementation simplicity is improved, but component stress and EMI increase

Engineering Contradiction:

Improveimplementation simplicityVSAvoidcomponent stress and EMI

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the operating parameter from discontinuous current mode to continuous current mode, maintaining implementation simplicity while eliminating the harmful effects of high peak currents and EMI associated with discontinuous mode operation

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If AC current sensing is implemented for continuous current mode control, then power factor correction accuracy is improved, but system complexity and noise susceptibility increase

Engineering Contradiction:

Improvepower factor correction accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the AC current sensing component from the system, achieving continuous current mode control through alternative means that reduce complexity and noise susceptibility while maintaining accuracy

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a waveform generator to create a reference waveform that copies the desired AC input current shape, enabling control without direct sensing of the actual current

Inventive Principle:

Principle #26Copying

3Reliability

If AC line voltage or current monitoring is added, then power factor correction performance is improved, but design complexity and cost increase

Engineering Contradiction:

Improvepower factor correction performanceVSAvoiddesign complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the requirement for AC line voltage or current monitoring from the system, achieving effective power factor correction through continuous current mode control with waveform generation alone, thereby reducing design complexity and cost

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS7315150B1Method of power conversion and apparatus which achieves high power factor correction using ripple current mode control

Publication Date: 2008.01.01 INTEGRATED CIRCUIT DESIGNS

AI summary

A ripple current mode power converter comprised of a magnetic energy storage element, and a method of determining magnetic storage element charge duration based on periodic magnetic storage element current samples. In the preferred embodiment a controller processes a magnetic storage element ripple current, and average sampled current, to achieve high power factor forgoing the need to sense the AC signal current and voltage levels. The controller element periodically calculates the magnetic storage element charge duration to control the state of the switch element to maintain the AC input current proportional to the AC input voltage.