Phase-Shifted Full-Bridge DC-DC Converter Reverse Power Control

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Solution Overview

Problem

Existing DC-DC converters, particularly phase-shifted full-bridge converters, face challenges in achieving efficient power transfer from the secondary side to the primary side without additional components, especially when the primary-side voltage exceeds the product of the secondary-side voltage and the transformer's transformation ratio.

Innovation Solution

The method involves a special switching state where the primary-side terminals of the transformer are connected to each other, and the secondary-side terminals of the transformer and DC-DC converter are connected, allowing for optimized switching patterns that reduce control accuracy demands and power losses in secondary-side switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the primary-side voltage exceeds the product of the secondary-side voltage and the transformer's transformation ratio, then power transfer in reverse direction can be achieved, but control accuracy requirements increase and power losses increase

Engineering Contradiction:

Improvereverse direction power transfer capabilityVSAvoidcontrol accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The switching cycle is divided into multiple distinct phases with specific switching states. The secondary-side switches are controlled to conduct during specific intervals, segmenting the power transfer process into controlled stages that reduce the control accuracy burden while maintaining reverse power transfer capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic switching patterns where the switching elements are controlled based on real-time operational conditions. The switching states are adjusted dynamically to optimize performance across different operating points, reducing control accuracy requirements while maintaining adaptability for reverse power transfer.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

Engineering Contradiction:

Improvereverse direction power transfer capabilityVSAvoidpower losses in secondary-side switches

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent implements periodic switching sequences where secondary-side switches are activated in specific repeating patterns. This periodic action allows the switches to conduct during optimal intervals, distributing stress and reducing average power losses while maintaining the capability for reverse direction power transfer.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The switching patterns and timing parameters are optimized to change based on operational conditions. By adjusting switching durations and sequences, the patent minimizes conduction losses in secondary-side switches while preserving reverse power transfer functionality.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If additional components are added to enable reverse power transfer, then power transfer in reverse direction can be achieved, but device complexity increases

Engineering Contradiction:

Improvereverse direction power transfer capabilityVSAvoidconverter structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the existing secondary-side switching elements serve dual functions: forward power conversion and reverse power transfer. By controlling these switches in different patterns, the same hardware achieves multiple operational modes without requiring additional components, thereby reducing device complexity while maintaining versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing switching elements on the secondary side are utilized to perform the reverse power transfer function. The system uses its own existing components to achieve additional functionality, eliminating the need for separate dedicated components and reducing overall device complexity.

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

This approach enables high-power transfer in the reverse direction with reduced losses and lower control accuracy requirements for transformers with low leakage inductance, while also minimizing power losses in secondary-side switching elements.

Implementation Method 1

A transformer is arranged between the primary side and the secondary side of the DC-DC converter

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

when active switching elements are also used on the secondary side

Methodology Applied

Scientific EffectActive switching:

Data Source

PatentUS12244235B2Control method for a DC-DC converter and dc-dc converter

Publication Date: 2025.03.04 ROBERT BOSCH GMBH

AI summary

A method for a phase-shifted full-bridge DC-DC converter. The method controls the DC-DC converter for energy transmission from a secondary side to a primary side of the DC-DC converter. A transformer is arranged between the primary side and the secondary side of the DC-DC converter. The method comprises a switching state, in which the terminals of the primary side of the transformer are electrically connected to one another, and in which, furthermore, the terminals of the secondary side of the transformer and the terminals of the secondary side of the DC-DC converter are electrically connected to one another.