Full-Bridge DC-DC Converter Topology for Lower Winding and Rectifier Losses

Solution Overview

Problem

Conventional isolated DC-DC converters face inefficiencies due to higher primary-winding area and losses, as well as increased losses in the secondary-side rectifier circuit, which can be attributed to the need for additional components and complex winding configurations.

Innovation Solution

A non-isolated full-bridge DC-DC converter design with a primary-side inverter and secondary-side rectifier, where the primary-side conduction paths share a common connection to the secondary winding, reducing the number of primary winding turns and minimizing rectifier current, thereby lowering losses and improving efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an isolated DC-DC converter design is used, then galvanic isolation between input and output is achieved, but primary-winding area and copper losses increase

Engineering Contradiction:

Improvegalvanic isolationVSAvoidcopper losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts the isolation function from the transformer by using a capacitor connected to the center tap of the primary winding. This capacitor blocks the DC component while allowing AC components to pass, achieving galvanic isolation without requiring traditional isolated transformer windings, thereby reducing copper losses and winding area.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a capacitor as an intermediary element between the primary and secondary sides. This capacitor serves as the isolation barrier, replacing the need for complex isolated transformer configurations and reducing the associated copper losses while maintaining galvanic isolation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If an isolated DC-DC converter design is used, then galvanic isolation is achieved, but the primary-winding area increases

Engineering Contradiction:

Improvegalvanic isolationVSAvoidprimary-winding area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the isolation function from the transformer by using a capacitor connected to the center tap of the primary winding. This capacitor blocks the DC component while allowing AC components to pass, achieving galvanic isolation without requiring traditional isolated transformer windings, thereby reducing copper losses and winding area.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the isolation mechanism from magnetic coupling in traditional transformers to capacitive coupling. This parameter change allows for reduced winding area while maintaining isolation, as the capacitor-based approach requires less physical space for the same isolation effect.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional isolated converter topology is used, then isolation is provided, but losses in the secondary-side rectifier increase

Engineering Contradiction:

ImproveisolationVSAvoidrectifier losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent merges the primary and secondary sides by directly connecting them through the transformer, eliminating the need for complex isolated rectifier circuits. The center-tapped primary configuration with capacitive isolation allows for simpler rectifier design on the secondary side, reducing rectifier losses while maintaining isolation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a capacitor as an intermediary element between the primary and secondary sides. This capacitor serves as the isolation barrier, replacing the need for complex isolated transformer configurations and reducing the associated copper losses while maintaining galvanic isolation.

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

The proposed design reduces primary-winding area and copper losses, enhances efficiency by minimizing rectifier power loss, and lowers costs through fewer PCB layers and reduced components.

Implementation Method 1

a transformer having a primary winding and a secondary winding

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an output filter connected to an output side of the secondary winding for filtering converter output current to reduce a switching-related AC component

Methodology Applied

Scientific EffectFiltering: Filter (electronic)

Data Source

PatentUS20260051823A1Non-isolated full bridge DC-DC converter

Publication Date: 2026.02.19 BEL FUSE MACAO COMML OFFSHORE

AI summary

A non-isolated converter includes a transformer having a primary winding and a secondary winding, a primary-side inverter, a secondary-side rectifier, and an output filter. The primary-side inverter is a full-bridge inverter providing two conduction paths for primary current during ON intervals of a switching cycle. The conduction paths are connected at a low-side common connection directly connected to the output side of the secondary winding, to provide the converter output current as the sum of the primary current and the secondary current during the ON intervals. Because the converter output includes a contribution from primary-side current due to the direct connection, certain advantages may be realized such as reduced primary-winding area/losses and reduced losses in the secondary-side rectifier.