Balanced Plate Rectifier Impedance Matching for High-Frequency Welding Power Supplies

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Solution Overview

Problem

Conventional plate rectifiers fail to adequately balance impedances for high-frequency loads, leading to current sharing imbalances, increased losses, heat generation, and reduced lifespan due to parasitic inductances and uneven temperature distribution among diodes.

Innovation Solution

The implementation of balanced plate rectifiers that symmetrically connect diodes and conductive plates to balance impedances, including parasitic inductances, between the terminals of high-frequency source currents, ensuring equal impedance across all current paths through the use of conductive plates and diodes connected via electrical conductors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional plate rectifiers are used with high-frequency loads, then the rectifier can process high-frequency currents, but impedance imbalance occurs due to parasitic inductances causing unequal current distribution among diodes

Engineering Contradiction:

Improvefrequency responseVSAvoidcurrent sharing balance

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies asymmetry by intentionally introducing balancing inductors with specific inductance values that are asymmetrically configured relative to the diodes. These inductors are designed to compensate for the inherent parasitic inductance differences in the circuit paths, creating symmetric total impedance despite the asymmetric physical layout and parasitic characteristics of individual components

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the impedance parameters by adding external inductors with specific inductance values (e.g., 10 nH, 20 nH, 30 nH) to each diode path. This parameter adjustment equalizes the total impedance across all current paths, ensuring balanced current distribution at high frequencies where parasitic inductances would otherwise cause significant imbalance

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional plate rectifier connections are used, then the structure is simple, but impedance imbalance leads to increased losses and heat generation

Engineering Contradiction:

Improverectifier structureVSAvoidpower loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent introduces inductors as intermediary elements between the diodes and the conductive plates. These inductors act as mediators that equalize the impedance in each current path, thereby reducing circulating currents and minimizing power losses without requiring a complete redesign of the rectifier structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the impedance balancing function by adding individual inductors to each diode path rather than using a single common inductor. This segmentation allows independent optimization of each current path's impedance, enabling precise control over current distribution while maintaining modular structure

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If conventional plate rectifier connections are used, then the configuration is straightforward, but uneven temperature distribution reduces component lifespan

Engineering Contradiction:

Improveinstallation simplicityVSAvoidcomponent lifespan

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent changes the electrical parameters (impedance) of each current path by adding inductors with specific values. This parameter adjustment equalizes the current through each diode, which directly equalizes the thermal load and temperature distribution, thereby extending component lifespan without complicating the installation procedure

Inventive Principle:

Principle #35Parameter changes

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 achieves balanced impedance across all diodes, reducing losses, heat generation, and extending the lifespan of the rectifier assembly by ensuring equal current sharing and temperature distribution, thereby improving the overall efficiency and rating of the rectifier.

Implementation Method 1

Conventional plate rectifiers do not adequately balance impedances for high-frequency loads, which causes portions of the plate rectifiers to experience heavier loads than other portions of the plate rectifiers. For example, conventional plate rectifiers may experience parasitic inductances which, when applied to high-frequency loads, can result in substantial imbalances in impedance.

Methodology Applied

Scientific EffectParasitic inductance: Inductor

Implementation Method 2

the rectifier including a first plate rectifier connected to a first output lead of the first transformer and a second output lead of the first transformer; a second plate rectifier connected to the first output lead and the second output lead

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11660697B2Balanced plate rectifiers and welding-type power supplies including balanced plate rectifiers

Publication Date: 2023.05.30 ILLINOIS TOOL WORKS INC

AI summary

A welding-type power supply including a balanced plate rectifier to rectify high frequency alternating current from one or more transformers. The balanced plate rectifier includes an output terminal symmetrically connected to the plates of the plate rectifiers. The impedance between the output terminal and each plate is substantially equal.