Opposing Unidirectional Contactors for Battery Isolation

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Solution Overview

Problem

Unidirectional contactors in energy storage systems have a shorter lifespan due to debris buildup from plasma arcs when current flows in both directions, leading to increased maintenance costs, while bidirectional contactors are more expensive.

Innovation Solution

The use of two unidirectional contactors with opposite polarities coupled to an energy storage device's terminals, controlled by a system that determines the direction of current flow to selectively open and close each contactor, thereby avoiding unintended current directions and extending contactor life without the need for bidirectional contactors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If unidirectional contactors are used to accommodate current flow in one direction, then the contactor design can use magnets and components to suppress plasma arcs, but when current flows in the opposite direction debris builds up between contactor plates leading to shorter contactor life

Engineering Contradiction:

Improvecontactor lifeVSAvoiddebris buildup from plasma arcs

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system divides the single contactor function into two separate unidirectional contactors, each handling one current direction. This segmentation allows each contactor to be optimized for its specific direction, suppressing plasma arcs effectively without debris buildup, thereby resolving the reliability issue caused by bidirectional operation of a single contactor

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of trying to make a single contactor handle both directions, the invention inverts the approach by using two contactors with opposite polarities. Each contactor is oriented to suppress plasma arcs in its designated direction, eliminating the harmful debris buildup that occurs when unidirectional contactors are forced to operate in reverse

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If bidirectional contactors are used to accommodate current flow in multiple directions, then contactor life is improved, but the expense increases

Engineering Contradiction:

Improvecontactor lifeVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system segments the bidirectional contactor function into two separate unidirectional contactors. Each unidirectional contactor is a simpler, less expensive component designed for a single direction, but together they achieve the bidirectional functionality needed for energy storage systems while reducing overall cost compared to using expensive bidirectional contactors

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a copied configuration of unidirectional contactors with opposite polarities to replicate the functionality of a single bidirectional contactor. This copying approach allows the system to achieve bidirectional current handling capability using multiple simpler, cheaper unidirectional units rather than one expensive bidirectional unit

Inventive Principle:

Principle #26Copying

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 allows for the use of unidirectional contactors in energy storage systems to handle bidirectional current flow, increasing their lifespan and reducing costs by preventing debris buildup and eliminating the need for more expensive bidirectional contactors.

Implementation Method 1

DC contactors typically used with energy storage systems can be unidirectional contactors designed to accommodate opening with current flowing in one direction. For instance, example contactors can make use of magnets and other components to suppress plasma arcs formed between contactor plates of the contactor as the contactor is opened.

Methodology Applied

Scientific EffectMagnetic field suppression of plasma arcs: Magnetic Field

Data Source

PatentUS9991714B2Opposing contactors for energy storage device isolation

Publication Date: 2018.06.05 GE GRID SOLUTIONS LLC

AI summary

An energy storage system can include an energy storage device, such as a battery energy storage device, having a first terminal and a second terminal. A first unidirectional contactor can be coupled to the first terminal. A second unidirectional contactor can be coupled to the second terminal. The first unidirectional contactor can be coupled to the energy storage device with opposite polarity relative to the second unidirectional contactor. The first unidirectional contactor and the second unidirectional contactor can be controlled based on direction of current flow associated with the energy storage device.