Coupled-Inductor Soft-Switching Converter for Low-Stress CCM Operation

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Solution Overview

Problem

Conventional soft-switching power converters require additional passive components, increasing circuit complexity and cost, and struggle with high switching stress and efficiency limitations in continuous conduction mode, making them unsuitable for higher power applications.

Innovation Solution

A soft-switching power converter design utilizing an inductive coupled unit with a main switch, an energy-releasing switch, and an auxiliary switch unit, which forms a closed loop to achieve zero-voltage or zero-current switching without additional passive components, reducing circuit volume and enhancing efficiency and power density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional soft-switching power converters use additional passive components (capacitors and inductors) to achieve zero-voltage switching, then switching loss is reduced, but circuit complexity and cost increase

Engineering Contradiction:

Improveswitching lossVSAvoidcircuit complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent merges the functions of additional passive components into the existing inductive coupled unit by utilizing its leakage inductance. The auxiliary switch unit is coupled to the second inductance to form a closed loop, eliminating the need for separate soft-switching components while achieving zero-voltage switching.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The inductive coupled unit serves multiple functions: it provides power conversion functionality while simultaneously serving as the soft-switching mechanism through its leakage inductance. The auxiliary switch unit coupled to the second inductance creates a resonant path that achieves zero-voltage switching without requiring dedicated soft-switching components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Stress or pressure

If additional passive components are added to achieve soft-switching, then switching stress is reduced, but circuit volume increases

Engineering Contradiction:

Improveswitching stressVSAvoidcircuit volume

Core Design Contradiction:

Stress or pressureVSVolume of stationary object

Solution Approach 1:

The patent combines the soft-switching function with the existing inductive coupled unit structure. The leakage inductance of the coupled unit is utilized as the resonant inductance for soft-switching, eliminating the need for additional large-volume passive components while reducing switching stress.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If operation mode is changed from CCM to CRM to reduce switching loss, then switching loss decreases, but control difficulty and filter requirements increase

Engineering Contradiction:

Improveswitching lossVSAvoidcontrol difficulty

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The auxiliary switch unit is controlled to start turning on before the main switch is turned on, creating a pre-charged resonant path. This preliminary action ensures that when the main switch turns on, the voltage across it is already zero, achieving soft-switching without requiring mode changes or complex control adjustments.

Inventive Principle:

Principle #10Preliminary action

4Power

If higher switching frequency is used to increase power density, then power density increases, but switching loss and efficiency decrease

Engineering Contradiction:

Improvepower densityVSAvoidswitching loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent employs periodic resonant action through the auxiliary switch unit coupled to the second inductance. This creates a controlled oscillating current path that naturally zeroes the voltage across the main switch before each switching cycle, enabling high-frequency operation with minimal switching loss.

Inventive Principle:

Principle #19Periodic action

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

The solution enables efficient zero-voltage or zero-current switching operations, simplifies the drive circuit design, and increases power density without additional passive components, making it suitable for higher power applications.

Implementation Method 1

The inductive coupled unit includes a first inductance, and a second inductance, and an auxiliary switch unit. The second inductance is coupled to the first inductance.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12132400B2Soft-switching power converter

Publication Date: 2024.10.29 DELTA ELECTRONICS INC(CN)

AI summary

A soft-switching power converter includes a main switch, an energy-releasing switch, and an inductive coupled unit. The main switch is a controllable switch. The energy-releasing switch is coupled to the main switch. The inductive coupled unit is coupled to the main switch and the energy-releasing switch. The inductive coupled unit includes a first inductance, a second inductance coupled to the first inductance, and an auxiliary switch unit. The auxiliary switch unit is coupled to the second inductance to form a closed loop. The main switch and the energy-releasing switch are alternately turned on and turned off. The auxiliary switch unit is controlled to start turning on before the main switch is turned on so as to provide at least one current path.