Ferromagnetic Attenuation Element for Power Converter Ringing

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Solution Overview

Problem

High-frequency electrical ringing in power converter arrangements causes electromagnetic interference, over-voltage, and power losses due to the resonance between capacitances, inductances, and resistances in RLC circuits, which is exacerbated by high switching frequencies and cannot be effectively attenuated without reducing efficiency.

Innovation Solution

A ferromagnetic attenuation element is magnetically coupled with the inductance of the RLC circuit to induce eddy currents, specifically tuned to attenuate the resonance frequency range rather than the semiconductor switching frequency, thereby reducing parasitic capacitance and inductance effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the resistance of the RLC circuit is increased to attenuate electrical ringing, then the electrical ringing is attenuated faster, but the power converter efficiency is reduced due to increased power dissipation

Engineering Contradiction:

Improveringing attenuationVSAvoidpower dissipation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

A ferromagnetic attenuation element is introduced as an intermediary component magnetically coupled to the RLC circuit. This element provides additional attenuation of electrical ringing through eddy currents and magnetic hysteresis without requiring increased resistance in the main power circuit, thus avoiding the power dissipation penalty.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the conventional approach of using resistive damping (electrical/mechanical system) with magnetic damping through a ferromagnetic attenuation element. The magnetic field interacts with the circuit inductance to provide attenuation through eddy currents and hysteresis losses confined to the attenuation element rather than the main power path.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If the switching frequency of the power converter semiconductors is increased to improve converter performance, then the converter efficiency and performance are improved, but the electrical ringing is amplified and causes electromagnetic interference

Engineering Contradiction:

Improveconverter performanceVSAvoidelectromagnetic interference

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful high-frequency switching transients into beneficial effects by using the ferromagnetic attenuation element to generate eddy currents and magnetic hysteresis losses that specifically dampen the ringing frequencies. The high switching frequency operation is maintained, but the harmful ringing is converted into controlled energy dissipation in the attenuation element.

Inventive Principle:

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

3Reliability

If the inductance and capacitance values of the RLC circuit are reduced to decrease electrical ringing, then the ringing amplitude is reduced, but the parasitic capacitance between conductors increases the resonance effect

Engineering Contradiction:

Improveringing suppressionVSAvoidparasitic capacitance effects

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the ringing attenuation function from the main RLC circuit components by introducing a separate ferromagnetic attenuation element. This element is magnetically coupled to the circuit but electrically isolated, allowing it to suppress ringing without being affected by or contributing to the parasitic capacitance between power conductors.

Inventive Principle:

Principle #2Taking out (Extraction)

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 effectively attenuates the resonance current, reducing electromagnetic interference, over-voltage spikes, and power losses in the resonant circuit while maintaining efficiency by dissipating energy through the ferromagnetic material.

Implementation Method 1

A ferromagnetic attenuation element is magnetically coupled with the inductance of the RLC circuit to induce eddy currents

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

induce eddy currents, specifically tuned to attenuate the resonance frequency range

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

dissipating energy through the ferromagnetic material

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11228234B2Power converter arrangement attenuation element for electrical ringing

Publication Date: 2022.01.18 ABB (SCHWEIZ) AG

AI summary

A power converter arrangement includes a semiconductor switch system with a controllable switch. A capacitor unit includes a capacitor having a capacitance value, the capacitor unit being operatively connected to the semiconductor switch system. A conductor arrangement includes a conductor adapted to conduct an electric current between the capacitor unit and the semiconductor switch system. The conductor has a resistance and an inductance. A resonant circuit is formed by the resistance, the inductance and the capacitance, and the power converter arrangement includes at least one attenuating element for attenuating an electrical ringing in the resonant circuit. The attenuating element is conductively isolated from the resonant circuit. The attenuating element includes ferromagnetic material, and the attenuating element is magnetically coupled to the conductor such that variations in the electric current intensity of the conductor induces eddy currents within the attenuating element.