Flyback Ripple Cancellation Circuit for Stable PFC Output

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Power factor correction flyback converters experience significant output ripples due to mismatches in input and output power, leading to voltage fluctuations, which are difficult to mitigate without increasing the complexity and cost of the power conversion system.

Innovation Solution

A ripple cancellation apparatus with magnetically coupled windings and an energy storage device is integrated into the flyback converter, allowing energy transfer between the magnetic core and the energy storage device to balance energy levels and cancel output ripples, thereby maintaining a stable output voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a large output capacitor is used to attenuate the 120 Hz output ripple, then the output voltage stability is improved, but the device complexity and cost increase

Engineering Contradiction:

Improveoutput voltage stabilityVSAvoiddevice complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent introduces a ripple cancellation apparatus as an intermediary component between the flyback converter and the output capacitor. This apparatus includes additional windings magnetically coupled to the flyback converter's primary winding, connected in series with the primary winding, and an energy storage device (capacitor) connected to these windings. The intermediary apparatus generates a ripple cancellation signal that opposes the output ripple, thereby reducing the burden on the output capacitor and allowing for smaller capacitor values while maintaining voltage stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the ripple filtering function into two parts: the traditional output capacitor filtering and the new ripple cancellation apparatus filtering. By dividing the ripple attenuation task between these two separate components, the system achieves better ripple reduction performance without requiring an excessively large output capacitor, thus balancing performance with component size and cost.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If a large output capacitor is used to attenuate the 120 Hz output ripple, then the output voltage stability is improved, but the cost increases

Engineering Contradiction:

Improveoutput voltage stabilityVSAvoidcost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The ripple cancellation apparatus serves as an intermediary that actively compensates for output ripple, allowing the use of smaller, less expensive output capacitors. The apparatus includes windings connected in series with the primary winding and an energy storage device that generates a cancellation signal, replacing the need for oversized capacitors and reducing overall component cost.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the flyback converter operates in discontinuous current mode to perform power factor correction, then the power factor correction function is achieved, but significant output ripples are generated

Engineering Contradiction:

Improvepower factor correction functionVSAvoidoutput ripples

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful output ripple generated by power factor correction operation into a beneficial effect by using it to charge the energy storage device in the ripple cancellation apparatus. The ripple signal, instead of being purely detrimental, is utilized to create a cancellation signal that opposes and reduces the output ripple, effectively transforming the problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The ripple cancellation apparatus acts as an intermediary that processes the ripple signal from the power factor correction operation and generates an opposing signal. The apparatus includes additional windings and an energy storage device that mediate between the flyback converter's output and the final output, canceling the harmful ripple effects while preserving the power factor correction functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution effectively reduces or eliminates output ripples, allowing for lower capacitor values and maintaining power factor correction without adding complexity or cost, ensuring a stable and efficient power delivery.

Implementation Method 1

The first winding L1 is magnetically couple to the second winding L2 through a magnetic core of the flyback converter

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentUS11923763B1Ripple cancellation apparatus and control method

Publication Date: 2024.03.05 HALO MICROELECTRONICS INT

AI summary

An apparatus includes a first winding and a first switch connected in series between an input terminal and ground, a second winding magnetically coupled to the first winding and coupled to an output terminal through a second switch, a third winding magnetically coupled to the first winding and connected in series with a fourth switch, a fourth winding magnetically coupled to the first winding and connected in series with a third switch, and an energy storage device connected between a common node of the third winding and the fourth winding, and ground.