Flexible Ceramic Resistor for Pulsed Power LTD

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Solution Overview

Problem

Existing pulsed power machines face challenges with aqueous-electrolyte resistors, such as leakage degrading dielectric strength, limited charge flow due to water resistivity, and mechanical issues with solid-state resistors like inflexibility and low power tolerance.

Innovation Solution

A solid-state resistor comprising a flexible string of ceramic resistors enclosed in an insulating outer shell with encapsulating oil, providing a resistance greater than 50 kohms, high impulse energy rating, and voltage hold-off capability, while being resistant to mechanical shocks and oil exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If aqueous-electrolyte resistors are used, then high power dissipation and high voltage capability are achieved, but leakage degrades dielectric strength of surrounding oil

Engineering Contradiction:

Improvepower dissipationVSAvoiddielectric strength degradation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The harmful aqueous electrolyte is extracted and replaced with solid-state ceramic resistors that provide the same electrical function without the leakage problem. The ceramic resistors are encapsulated in an insulating shell to completely isolate any potential contaminants from the surrounding insulating oil, eliminating the dielectric strength degradation issue while maintaining high power dissipation capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The resistor material undergoes a parameter change from liquid aqueous electrolyte to solid ceramic material. This phase change eliminates the leakage characteristic while maintaining the electrical resistance function. The solid-state ceramic provides the same high power dissipation and voltage handling capabilities without the harmful liquid leakage that degrades oil dielectric strength.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If aqueous-electrolyte resistors are used, then ease of manufacture is improved, but charge flow is limited by water resistivity

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcharge flow capability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention uses composite material construction with multiple ceramic resistors connected in series and parallel configurations within an insulating shell. This composite approach allows precise control of total resistance value and charge flow characteristics by combining individual ceramic resistor elements, achieving both manufacturing flexibility and reliable charge flow capability without electrolysis limitations.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If solid-state resistors are used, then dielectric strength is maintained, but mechanical inflexibility and low power tolerance occur

Engineering Contradiction:

Improvedielectric strength maintenanceVSAvoidmechanical flexibility

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The solid-state resistor is segmented into multiple discrete ceramic resistor elements rather than a single monolithic component. These segmented elements are arranged in a flexible string configuration within the insulating shell, allowing the assembly to accommodate mechanical shocks and vibrations while maintaining the high voltage hold-off capability of solid-state ceramics. The segmentation also distributes power dissipation across multiple elements, improving overall power tolerance.

Inventive Principle:

Principle #1Segmentation

4Reliability

If solid-state resistors are used, then voltage hold-off capability is improved, but power tolerance is reduced

Engineering Contradiction:

Improvevoltage hold-off capabilityVSAvoidpower tolerance

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

Multiple ceramic resistor elements are merged in a series-parallel configuration within the insulating shell. The series connections provide high voltage hold-off capability by distributing voltage across multiple elements, while the parallel connections increase power tolerance by distributing power dissipation across multiple elements. This merging strategy simultaneously achieves both high voltage capability and high power tolerance that single solid-state resistors cannot provide.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively quenches switch prefires, survives multiple machine shots, and maintains high energy handling capacity without causing oil contamination or mechanical failure, enhancing the reliability and performance of pulsed power systems.

Implementation Method 1

insulating oil contained within the outer shell and encapsulating the string of ceramic resistors

Methodology Applied

Scientific EffectDielectric insulation: Dielectric

Implementation Method 2

high power dissipation

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS9514864B2Solid-state resistor for pulsed power machines

Publication Date: 2016.12.06 NATIONAL TECHNOLOGY & ENGINEERING SOLUTIONS OF SANDIA LLC

AI summary

A flexible solid-state resistor comprises a string of ceramic resistors that can be used to charge the capacitors of a linear transformer driver (LTD) used in a pulsed power machine. The solid-state resistor is able to absorb the energy of a switch prefire, thereby limiting LTD cavity damage, yet has a sufficiently low RC charge time to allow the capacitor to be recharged without disrupting the operation of the pulsed power machine.