Modular Stacked DC Architecture for Traction Systems

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Solution Overview

Problem

Hybrid and electric vehicles face inefficiencies in managing high voltage energy storage systems, as high voltage DC-DC converters require expensive switches, and cell voltage balancing in series cells leads to capacity degradation, necessitating the use of low voltage systems.

Innovation Solution

A modular stacked DC architecture propulsion system with low voltage energy storage devices and bi-directional DC-DC converters, coupled with a controller to manage energy transfer between the energy storage devices and the DC link, allowing for efficient operation and cost reduction by using less expensive switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high voltage energy storage systems are used, then power and energy capacity are improved, but system cost increases due to expensive high voltage switches

Engineering Contradiction:

Improvepower capacityVSAvoidsystem cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The energy storage system is divided into multiple low voltage modules (e.g., 48V modules) connected in series to achieve the required high voltage output (e.g., 192V). Each module uses inexpensive low voltage switches, and the modular architecture allows the system to achieve high power capacity without requiring expensive high voltage switches in each individual module.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If series cell configuration is used, then voltage requirements are met, but cell voltage balancing issues cause capacity degradation

Engineering Contradiction:

Improvevoltage utilizationVSAvoidcapacity retention

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The series cell configuration is segmented into multiple low voltage modules, each with its own energy storage devices connected in series. This segmentation reduces the voltage stress on individual cells and allows for better voltage balancing within each module, preventing capacity degradation while still meeting the overall high voltage requirements of the propulsion system.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If low voltage energy storage devices are used, then system cost is reduced, but power delivery capability may be insufficient

Engineering Contradiction:

Improvesystem costVSAvoidpower delivery

Core Design Contradiction:

Ease of manufactureVSPower

Solution Approach 1:

Multiple low voltage energy storage modules are merged in series to achieve the required high voltage output. The combined power delivery capability of all modules meets or exceeds the requirements of the propulsion system, while each individual module uses inexpensive low voltage components. The controller coordinates energy transfer between modules to optimize power delivery.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If modular stacked DC architecture is implemented, then system flexibility and efficiency are improved, but system complexity increases

Engineering Contradiction:

Improvesystem flexibilityVSAvoidsystem architecture

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The propulsion system is segmented into standardized modular units (energy storage modules, converter modules, controller modules) that can be independently designed, tested, and assembled. This modular architecture improves flexibility and adaptability while the standardization of interfaces and protocols reduces the effective complexity through modularity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The modular DC architecture uses universal interfaces and standardized voltage levels across all modules, allowing the same basic module design to serve multiple functions and be configured for different power requirements. This universality reduces complexity by eliminating the need for custom designs for each application.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables efficient energy management and cost reduction by using low voltage switches, maintaining energy storage capacity and torque efficiency, while reducing the reliance on expensive high voltage components.

Implementation Method 1

bi-directional DC-DC converters, coupled with a controller to manage energy transfer between the energy storage devices and the DC link

Methodology Applied

Scientific EffectElectrical energy conversion:

Data Source

PatentUS10044312B2Modular stacked DC architecture traction system and method of making same

Publication Date: 2018.08.07 BUNKER HILL TECHNOLOGIES LLC

AI summary

A modular stacked DC architecture for traction system includes a propulsion system includes an electric drive, a direct current (DC) link electrically coupled to the electric drive, and a first DC-DC converter coupled to the DC link. A first energy storage device (ESD) is electrically coupled to the first DC-DC converter, and a second DC-DC converter is coupled to the DC link and to the first DC-DC converter. The system also includes a second energy storage device electrically coupled to the second DC-DC converter and a controller coupled to the first and second DC-DC converters and configured to control a transfer of energy between the first ESD and the DC link via the first and second DC-DC converters.