Flyback Converter Clamping Circuit for Leakage Inductance Damping

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Solution Overview

Problem

Flyback DC-DC converters face challenges due to leakage inductance, which leads to power losses, voltage spikes, and increased electromagnetic interference (EMI), affecting efficiency and component stress.

Innovation Solution

The implementation of a flyback DC-DC converter circuit that includes a clamping switch and a damping resistor, along with precise control of the clamping switch's turn-on time, is used to absorb and discharge leakage inductance energy, thereby reducing its effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If leakage inductance energy is not managed, then the converter structure remains simple, but power losses increase and efficiency decreases

Engineering Contradiction:

Improvepower lossesVSAvoidconverter structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

A damping resistor is introduced as an intermediary component to dissipate leakage inductance energy. The resistor is connected in parallel with the primary winding of the transformer, providing a controlled path for leakage energy dissipation without requiring fundamental changes to the converter topology.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damping resistor value is optimized to achieve critical damping conditions, transforming the underdamped oscillatory response into a critically damped response. This parameter optimization minimizes power losses while maintaining a relatively simple circuit structure.

Inventive Principle:

Principle #35Parameter changes

2Strength

If leakage inductance energy is not managed, then the circuit remains simple, but voltage spikes increase and component stress increases

Engineering Contradiction:

Improvecomponent stress resistanceVSAvoidcircuit structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The damping resistor serves as a protective intermediary that limits voltage spikes by providing a discharge path for leakage inductance energy. This reduces stress on switches and other components without requiring complex protection circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damping resistor is pre-configured to provide cushioning against voltage spikes before they can damage components. By having the resistor in place beforehand, the circuit is prepared to absorb and dissipate energy that would otherwise cause harmful voltage transients.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If leakage inductance energy is not managed, then the circuit configuration remains simple, but electromagnetic interference increases

Engineering Contradiction:

Improveelectromagnetic interferenceVSAvoidcircuit configuration

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The damping resistor acts as an intermediary that suppresses oscillations caused by leakage inductance, thereby reducing electromagnetic interference. By damping the resonant oscillations between leakage inductance and parasitic capacitances, the resistor minimizes EMI without requiring complex filtering circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Use of energy by moving object

If leakage inductance energy is not managed, then the converter design remains simple, but efficiency decreases

Engineering Contradiction:

Improveconverter efficiencyVSAvoidconverter design

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

By optimizing the damping resistor value to achieve critical damping, the converter efficiency is improved through minimized energy losses. The parameter optimization ensures that the resistor dissipates only the necessary leakage energy while maintaining high efficiency for the primary power transfer function.

Inventive Principle:

Principle #35Parameter changes

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 approach reduces power losses, minimizes voltage spikes and oscillations, improves efficiency, and enhances electromagnetic compatibility (EMC) performance by effectively managing leakage inductance energy.

Implementation Method 1

a resonance time period of a resonator, the resonator formed by a leakage inductance of the transformer and a capacitance of the capacitor

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

a damping resistor, along with precise control of the clamping switch's turn-on time, is used to absorb and discharge leakage inductance energy

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS12244225B2Systems and methods for reducing effects of leakage inductance in flyback DC-DC converters

Publication Date: 2025.03.04 NAVITAS SEMICON LTD

AI summary

A flyback DC-DC converter. The converter having a transformer with a primary and a secondary windings, first and second switches, a capacitor coupled between the second switch and the primary winding, where the second switch is arranged to operate such that a sum of a first and second time periods equals a sum of third and fourth time periods, where the first time period is a delay time period from a time that the first switch is turned off to a time that the second switch is turned on, the second time period is a time period that the second switch is on, the third time period is a resonance time period of a resonator formed by a leakage inductance of the transformer and a capacitance of the capacitor, and the fourth time period is a time period for discharge of the leakage inductance of the transformer into the capacitor.