Interleaved PFC Autotransformer Control Against Core Saturation

Solution Overview

Problem

High-power AC-DC power modules using interleaved parallel PFC circuits face issues with magnetic core saturation in autotransformers due to parameter differences and switch drive delays, leading to switching device failure.

Innovation Solution

A controller dynamically adjusts the duty cycle of switching transistors in rectifier bridge arms based on current differences between the windings of the autotransformer to prevent magnetic core saturation by reducing the exciting current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If interleaved parallel PFC circuits are used to achieve high-power output, then power output is improved, but magnetic core saturation occurs due to parameter differences and switch drive delays

Engineering Contradiction:

Improvepower outputVSAvoidswitching device reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent applies dynamics by making the dead time of switching devices adjustable rather than fixed. The control device dynamically adjusts the dead time based on real-time detection of volt-second products, allowing the system to adapt to varying operating conditions and prevent magnetic core saturation while maintaining high-power output capability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by detecting the volt-second product of the autotransformer in real-time and using this information to adjust the dead time of switching devices. This closed-loop control ensures that the magnetic core operates within safe limits while maintaining optimal power conversion efficiency

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If autotransformer is added to achieve good current equalization characteristic, then current equalization is improved, but magnetic core saturation occurs due to parameter differences

Engineering Contradiction:

Improvecurrent equalization characteristicVSAvoidcircuit reliability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies dynamics by making the dead time of switching devices adjustable rather than fixed. The control device dynamically adjusts the dead time based on real-time detection of volt-second products, allowing the system to adapt to varying operating conditions and prevent magnetic core saturation while maintaining high-power output capability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by detecting the volt-second product of the autotransformer in real-time and using this information to adjust the dead time of switching devices. This closed-loop control ensures that the magnetic core operates within safe limits while maintaining optimal power conversion efficiency

Inventive Principle:

Principle #23Feedback

3Device complexity

If fixed dead time is used in switching devices, then device complexity is reduced, but magnetic core saturation occurs due to switch drive delay differences

Engineering Contradiction:

Improvecontrol circuit complexityVSAvoidswitching device reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by making the dead time of switching devices adjustable rather than fixed. The control device dynamically adjusts the dead time based on real-time detection of volt-second products, allowing the system to adapt to varying operating conditions and prevent magnetic core saturation while maintaining high-power output capability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by detecting the volt-second product of the autotransformer in real-time and using this information to adjust the dead time of switching devices. This closed-loop control ensures that the magnetic core operates within safe limits while maintaining optimal power conversion efficiency

Inventive Principle:

Principle #23Feedback

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 prevents switching device damage and enhances the operating reliability of the circuit by maintaining the magnetic core in an unsaturated state.

Implementation Method 1

a volt-second product of the autotransformer may exceed an allowable value of a magnetic core, resulting in saturation of the magnetic core of the autotransformer

Methodology Applied

Scientific EffectMagnetic saturation: Magnetic Saturation

Implementation Method 2

an autotransformer is usually added to a circuit topology

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20260088712A1Power module and charging device

Publication Date: 2026.03.26 HUAWEI DIGITAL POWER TECH CO LTD

AI summary

A power module includes N groups of interleaved parallel PFC circuits and a controller. Each group of the interleaved parallel PFC circuits includes a PFC inductor, an autotransformer, a first rectifier bridge arm, and a second rectifier bridge arm. The autotransformer includes a first winding and a second winding that are coupled to each other. The controller is configured to: in response to that an absolute value of a difference between a current of the first winding and a current of the second winding is greater than or equal to a preset value, adjust a duty cycle of a drive signal of a switching transistor of the first rectifier bridge arm or the second rectifier bridge arm in a next switching cycle.