Varistor Assembly Parallel Segmentation Surge Protection

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Solution Overview

Problem

Conventional varistors fail to achieve sufficient surge breakdown voltage while maintaining low capacitance, particularly in high-energy applications, leading to inadequate protection against abnormal voltages such as surges and static electricity.

Innovation Solution

A varistor assembly comprising multiple varistor elements connected in parallel, with a sintered body having a high surface area-volume ratio (S/V ≥ 1.9 mm^-1), where each element includes a laminate structure of varistor layers and internal electrodes, enhancing surge breakdown voltage while minimizing capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the element size is enlarged and the internal electrode area is expanded to protect from high-energy surges, then the surge protection capability is improved, but the capacitance becomes too large

Engineering Contradiction:

Improvesurge protection capabilityVSAvoidcapacitance

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent divides a single large-capacitance varistor into multiple smaller varistor elements connected in parallel. Each element has its own electrodes and varistor layer, with individual capacitances that sum to the total required capacitance. This segmentation allows the system to achieve the necessary surge protection capability while keeping individual element capacitances low, thereby resolving the contradiction between surge protection and capacitance control.

Inventive Principle:

Principle #1Segmentation

2Power

If the element size is enlarged to achieve sufficient surge breakdown voltage, then the energy handling capability is improved, but the surface area to volume ratio decreases leading to reduced heat dissipation efficiency

Engineering Contradiction:

Improvesurge breakdown voltageVSAvoidheat dissipation efficiency

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

By segmenting the varistor into multiple smaller elements, each element maintains a high surface area to volume ratio, which improves heat dissipation efficiency. The parallel connection of multiple elements provides the required surge breakdown voltage and energy handling capability while each individual element dissipates heat more effectively due to its smaller size and higher surface area to volume ratio.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines multiple varistor elements in parallel to achieve the required power handling and surge breakdown voltage. The merging of multiple high heat-dissipation elements provides both the necessary voltage capability and superior thermal performance compared to a single large element, resolving the contradiction between power capability and heat dissipation.

Inventive Principle:

Principle #5Merging (Combining)

3Use of energy by moving object

If the internal electrode area is expanded to increase capacitance for energy absorption, then the surge energy handling is improved, but the device size increases

Engineering Contradiction:

Improvesurge energy handlingVSAvoiddevice size

Core Design Contradiction:

Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The patent segments the total capacitance requirement into multiple smaller capacitances distributed across parallel elements. This allows the system to absorb the required surge energy through the combined capacitance of multiple small elements rather than requiring a single large element, thereby reducing the overall device size while maintaining energy handling capability.

Inventive Principle:

Principle #1Segmentation

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 configuration achieves a significant improvement in surge breakdown voltage and withstand characteristics, allowing for effective protection against high-energy surges while reducing the electrode area and maintaining high heat dissipation, thus overcoming the limitations of conventional varistors.

Implementation Method 1

maintaining high heat dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11545284B2Varistor assembly

Publication Date: 2023.01.03 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

Provided is a varistor assembly capable of achieving good surge breakdown voltage while suppressing capacitance. The varistor assembly is obtained by connecting a plurality of varistor elements in parallel. Each varistor element includes: a sintered body obtained by sintering a laminate in which varistor layers and internal electrodes are alternately laminated; and a pair of external electrodes provided in a state where the internal electrodes are alternately connected on at least both end faces of this sintered body. Varistor element includes at least a plurality of first group varistor elements in which a value obtained by dividing a surface area of the sintered body by a volume of the sintered body is 1.9 mm−1 or more.