Non-Isolated Full-Bridge Converter With Synchronous Rectification

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Solution Overview

Problem

Conventional DC-to-DC power converters require transformers for high voltage conversion, leading to significant winding losses and increased costs due to large primary turns and high AC content in secondary windings, which is particularly problematic in datacenters transitioning to higher voltage infrastructure.

Innovation Solution

A non-isolated DC-to-DC power converter with interconnected transformer windings and synchronous rectification mode, utilizing a full bridge configuration with switching elements and control circuitry to regulate output voltage, reducing the need for traditional transformers and minimizing winding losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a transformer is used for high voltage conversion in conventional DC-to-DC power converters, then voltage conversion capability is improved, but winding losses increase and cost increases

Engineering Contradiction:

Improvevoltage conversion capabilityVSAvoidwinding losses

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent extracts the transformer from the conventional isolated topology and reconfigures it as a non-isolated converter with interconnected windings. The primary and secondary windings are connected in series to form a single continuous winding, eliminating the need for galvanic isolation while maintaining voltage conversion capability through the full-bridge topology and synchronous rectification.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the primary and secondary windings into a single continuous winding by connecting them in series. This combining of previously separate isolated circuits allows the system to operate without galvanic isolation while maintaining the transformer's voltage conversion function through the full-bridge switching topology.

Inventive Principle:

Principle #5Merging (Combining)

2Power

If a transformer with large primary turns is used for high voltage conversion, then voltage conversion ratio is improved, but winding cost and PCB cost increase

Engineering Contradiction:

Improvevoltage conversion ratioVSAvoidwinding cost and PCB cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent changes the operational parameters of the transformer by operating it in a non-isolated mode with interconnected windings. This allows the use of fewer turns while achieving the same voltage conversion ratio through the full-bridge topology and synchronous rectification, thereby reducing winding complexity and cost.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional isolated transformer mechanism with a non-isolated full-bridge converter topology. This substitution eliminates the need for large primary turns by using switching elements and synchronous rectification to achieve voltage conversion, reducing both winding cost and PCB real estate requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If synchronous rectification mode is used in the full bridge configuration, then conversion efficiency is improved, but control complexity increases

Engineering Contradiction:

Improveconversion efficiencyVSAvoidcontrol complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent implements self-service control where the control circuitry automatically generates complementary gate signals for the switching elements based on the operation mode. The system self-regulates by detecting whether to operate in power conversion mode or synchronous rectification mode and adjusts the gate signals accordingly, reducing the need for external complex control mechanisms.

Inventive Principle:

Principle #25Self-service

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 proposed solution achieves higher efficiency and reduced costs by minimizing winding losses and circuit board costs, while maintaining effective voltage regulation across varying input and output conditions.

Implementation Method 1

a first circuit path including a series combination of a primary winding of a transformer and a first secondary winding of the transformer

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The control circuitry operates the first upper switching element and the second upper switching element in a synchronous rectification mode

Methodology Applied

Scientific EffectSynchronous rectification:

Data Source

PatentUS20260031730A1Non-isolated full bridge power converter drive system

Publication Date: 2026.01.29 FLEX LTD

AI summary

An apparatus includes multiple switching elements operable to convey energy from a voltage source to the primary winding of the transformer. The switching elements include first switching elements connected on a first side of the transformer, including a first upper switching element, a first middle switching element, and a first lower switching element. The switching elements include second switching elements connected on a second side of the transformer opposite the first side of the transformer, the second switching elements including a second upper switching element, a second middle switching element, and a second lower switching element. Control circuitry controls switching of the first switching elements and the second switching elements to regulate an output voltage of the apparatus by operating the first upper switching element and the second upper switching element in a synchronous rectification mode.