Cell-Based DC/DC Converter with Galvanic Isolation

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Solution Overview

Problem

Existing cell-based DC/DC converters are expensive due to the requirement of two groups of converter cells on both sides of the transformer, which increases costs and complexity.

Innovation Solution

A DC/DC converter design featuring a first conversion branch with controllable voltage sources connected through a transformer, allowing for economical and cost-efficient operation with reduced harmonic distortion, enabling different magnitudes and galvanic separation of DC voltages, using a configuration of half-bridge converter cells and capacitor banks symmetrically arranged around the transformer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two groups of converter cells are used on both sides of the transformer, then voltage conversion and galvanic separation are achieved, but device cost and complexity increase significantly

Engineering Contradiction:
Improvevoltage conversion capabilityVSAvoidconverter cell configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The converter is divided into two independent single-phase full-bridge converters operating in parallel, each handling one phase of the three-phase system. This segmentation allows each converter to be simpler while collectively achieving the required three-phase voltage conversion and galvanic separation functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each full-bridge converter cell is designed to perform multiple functions: voltage conversion, galvanic isolation, and harmonic filtering. By making each cell multi-functional, the overall system achieves complex capabilities without proportionally increasing the number of components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Power

If traditional cell-based DC/DC converter structure is used, then voltage levels are provided, but manufacturing cost increases

Engineering Contradiction:
Improvediscrete voltage levelsVSAvoidconverter cost
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

Multiple converter cells are merged into a single integrated full-bridge converter structure. Instead of using separate cells that would require individual mounting and interconnection, the cells are combined into one unified module, reducing assembly complexity and manufacturing cost while maintaining the ability to provide discrete voltage levels.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If converter cells are configured for DC voltage provision and AC voltage production, then voltage adjustment is possible, but device complexity and cost increase

Engineering Contradiction:
Improvevoltage adjustment capabilityVSAvoidconverter structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The converter employs dynamic control of the full-bridge switching elements to achieve variable voltage output. By dynamically adjusting the switching patterns and duty cycles, the converter can adapt to different voltage requirements without requiring multiple fixed-configuration converter stages, thus maintaining versatility while reducing structural complexity.

Inventive Principle:
Principle #15Dynamics

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 provides a cost-efficient DC/DC converter with reduced harmonic distortion and the ability to handle different DC voltage magnitudes while maintaining galvanic separation, enhancing the converter's operational efficiency and flexibility.

Implementation Method 1

a transformer with a primary winding connected in a first interconnecting branch stretching between a first junction at which the first and second controllable voltage sources are connected to each other and a first potential that lies in the middle between the potentials of the first and second DC terminal, and a secondary winding connected to another end of the conversion unit

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2594015B1Cell based DC/DC converter
Publication Date: 2015.03.04 ABB TECHNOLOGY AG
  • EP2594015B1 patent drawingFigure 1~2
  • EP2594015B1 patent drawingFigure 3~4
  • EP2594015B1 patent drawingFigure 5A~6

AI summary

The invention concerns a DC/DC converter (10) comprising a first conversion branch stretching between a first and a second DC terminal (18, 20), a first controllable voltage source (UbIp) in a first half of the first conversion branch, a second controllable voltage source (UbIn) in a second half of the first conversion branch, a conversion unit (14A) converting between AC and DC and at one end connected to a third and a fourth DC terminal (22, 24), and a transformer (16) with a primary winding connected in a first interconnecting branch stretching between a first junction at which the first and second controllable voltage sources are connected to each other and a first potential that lies in the middle between the potentials of the first and second DC terminal, and a secondary winding connected to another end of the conversion unit.