DC Link Fuse Assembly for Capacitor Short-Circuit Protection

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Solution Overview

Problem

Power converters face challenges in protecting capacitors from short circuits, which can lead to component failure, high currents, and potential fires, especially during component failure tests.

Innovation Solution

The implementation of a fuse assembly with a fuse element in parallel with a capacitive element, connected to the positive or negative bus, provides impedance and a current path to unaffected capacitors, preventing damage during short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fuse assembly with a capacitive element is added to protect capacitors from short circuits, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvecapacitor protectionVSAvoidfuse assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A capacitive element is introduced as an intermediary component between the fuse element and the DC link capacitors. This capacitive element acts as a mediator that absorbs surge currents and prevents direct short circuit paths, thereby protecting the capacitors while maintaining a relatively simple overall structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The capacitive element provides beforehand cushioning by being pre-configured in parallel with the fuse element to absorb and dissipate energy from potential short circuits before they can damage the DC link capacitors. This preventive measure ensures capacitor protection is already in place before a fault occurs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Object-affected harmful factors

If the fuse assembly provides a current path through the capacitive element, then harmful factors are reduced, but energy loss increases

Engineering Contradiction:

Improvesurge currentVSAvoidenergy dissipation

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The harmful surge current is converted into a beneficial protective mechanism. The capacitive element absorbs the harmful surge energy and dissipates it safely through the fuse element, transforming what would be a destructive force into a controlled protective action that prevents capacitor damage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 configuration effectively manages surge currents, prevents capacitor damage, and ensures compliance with component failure tests by providing a safe path for current during short circuits.

Implementation Method 1

a fuse element in parallel with a capacitive element, the fuse element being configured to open in response to a short circuit in the one of the capacitors in the group of capacitors such that the capacitive element provides an impedance and a current path

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20250125717A1Capacitor protection in a power converter

Publication Date: 2025.04.17 EATON INTELLIGENT POWER LTD

AI summary

A system includes: a DC bus electrically configured for connection to one or more of a rectifier and an inverter, the DC bus including a positive bus and a negative bus; and a DC link electrically connected to the DC bus. The DC link includes: an energy storage apparatus includes at least two energy storage elements; and a fuse assembly electrically connected the energy storage apparatus and to one of the positive bus and the negative bus.