Hierarchical DC-DC Converter Topology for Energy Storage Testing

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Solution Overview

Problem

Current cell testers are inefficient, costly, and inflexible due to the use of linear position controllers and complex regenerative switching converters, leading to high energy losses and cooling costs during battery testing and formation.

Innovation Solution

A hierarchical test arrangement with multiple module DC-DC converters connected in parallel to an AC-DC converter, allowing for flexible configuration and efficient energy distribution by using switches to connect outputs in series, prioritizing the highest converter stage for energy supply and enabling efficient testing and emulation of energy storage units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If linear position controllers are used in cell testers, then the device complexity is reduced, but the efficiency deteriorates and energy losses increase

Engineering Contradiction:
Improvedevice complexityVSAvoidenergy losses
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent changes the control parameter from linear position control to pulse-width modulation (PWM) switching control, enabling efficient energy transfer while maintaining manageable device complexity through standardized converter modules

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If regenerative switching converters are used to map high voltage ratio (3V to 400V), then the efficiency is improved, but the device complexity and cost increase

Engineering Contradiction:
ImproveefficiencyVSAvoiddevice complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent segments the voltage conversion function into multiple hierarchical DC-DC converter stages (module level and cell level), each handling a portion of the voltage ratio, thereby reducing the complexity of individual converters while maintaining high efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a nested converter architecture where cell DC-DC converters are nested within module DC-DC converters, which are in turn nested within the overall test arrangement, allowing efficient energy transfer through hierarchical power management

Inventive Principle:
Principle #7Nested doll (Nesting)

3Adaptability or versatility

If the test arrangement structure is changed to test different energy storage configurations, then the adaptability is improved, but the device complexity increases

Engineering Contradiction:
ImproveadaptabilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal test arrangement architecture where the same hierarchical DC-DC converter structure can test various energy storage configurations (individual cells, modules, or complete packs) by simply reconfiguring connections rather than changing the fundamental device structure

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

Solution Approach 2:

The patent introduces dynamic reconfigurability through controllable switches that allow the test arrangement to adapt its topology in real-time, enabling transition between different testing modes without physical reconfiguration of the converter structure

Inventive Principle:
Principle #15Dynamics

4Device complexity

If linear position controllers are used, then the cooling system requirements are reduced, but the efficiency deteriorates and energy costs increase

Engineering Contradiction:
Improvecooling system complexityVSAvoidenergy costs
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent changes the operating parameters of the power conversion system by using PWM switching control instead of linear control, achieving high efficiency operation that minimizes heat generation and reduces cooling system requirements

Inventive Principle:
Principle #35Parameter changes

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 hierarchical structure achieves an efficiency advantage of approximately 17% by utilizing the highest converter stage for most of the test time, reducing energy losses and increasing flexibility in testing and forming energy storage devices, from individual units to entire modules.

Implementation Method 1

an AC/DC converter which is connected to a voltage supply on the input side and is connected to at least one bidirectional, isolated module DC/DC converter on the output side

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP2920599B1Testing assembly for an energy storage device
Publication Date: 2020.08.12 AVL LIST GMBH
  • EP2920599B1 patent drawingFigure 1
  • EP2920599B1 patent drawingFigure 1
  • EP2920599B1 patent drawingFigure 2

AI summary

The invention relates to an efficient, economical, and at the same time flexibly usable or configurable testing assembly for energy stores comprising several energy storage modules for several energy storage units each. According to the invention an AC/DC converter (2) is connected on the output side to at least one bidirectional isolated module DC/DC converter (51...5n), wherein the output of the bidirectional isolated module DC/DC converter (51...5n) is connected to a plurality of cell DC/DC converters (611...6nm) connected in parallel and the outputs of the cell DC/DC converters (611...6nm) are fed outside as outputs (A1+, A1-...Ax+, Ax-) of the testing assembly (1).