Integrated Power Source for Resistance Welding Gun

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Solution Overview

Problem

Resistance welding devices experience high losses due to heavy-current transformers and power lines, leading to inefficient energy use and significant heat dissipation, resulting in poor efficiency and high operational costs in production lines, especially in the automotive industry.

Innovation Solution

A resistance welding device with a power source integrated into the welding gun, utilizing a heavy-current transformer with a multi-point contacting system and synchronous rectifier, which reduces line lengths and contact resistances, and integrates the synchronous rectifier and actuation circuit directly into the transformer, allowing for shorter lines and increased contact areas, thereby minimizing losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a separate design of heavy-current transformer and rectifier is used, then the device structure is simple, but the line lengths are significant causing high power losses

Engineering Contradiction:

Improvepower lossesVSAvoiddevice structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines the heavy-current transformer and rectifier into an integrated power source unit. The transformer secondary windings are directly connected to the rectifier circuit elements without intermediate power lines, eliminating line losses while maintaining structural simplicity through functional integration.

Inventive Principle:

Principle #5Merging (Combining)

2Loss of energy

If active rectifiers comprising control elements are employed, then rectification efficiency is improved, but the device still has relatively high losses

Engineering Contradiction:

Improverectification lossesVSAvoidcontrol elements

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent uses the magnetic field generated by the heavy current flow beneficially for actuating the circuit elements of the synchronous rectifier. The control circuit detects current direction and timing through magnetic field sensing, converting the harmful high current into a useful control signal source, thereby reducing losses without requiring complex external control systems.

Inventive Principle:

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

3Loss of energy

If heavy currents occur in resistance welding devices, then welding performance is achieved, but diode rectifiers cause relatively high losses

Engineering Contradiction:

Improverectifier lossesVSAvoidwelding current

Core Design Contradiction:

Loss of energyVSPower

Solution Approach 1:

The patent replaces diode rectifiers with active circuit elements (transistors or thyristors) that can be precisely controlled to achieve synchronous rectification. These solid-state switching devices substitute for passive diodes, enabling bidirectional current control and significantly reducing rectification losses during heavy current welding operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Loss of energy

If significant line lengths are used to connect transformer and rectifier, then device layout is flexible, but power losses are high

Engineering Contradiction:

Improveline lossesVSAvoiddevice layout flexibility

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The patent integrates the transformer and rectifier into a single compact power source assembly where the secondary windings are directly coupled to the rectifier circuit elements. This eliminates the need for long connecting lines and heavy current cables, reducing ohmic losses while maintaining layout flexibility through the modular design of the integrated unit.

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

This configuration reduces connected wattage requirements and achieves higher efficiency, with losses decreased from 135 kW to 60 kW, doubling the efficiency to around 20%, and allowing for a more compact and cost-effective design.

Implementation Method 1

a heavy-current transformer with at least one primary winding and at least one secondary winding with center tapping

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a synchronous rectifier connected with the at least one secondary winding of the heavy-current transformer and comprising circuit elements

Methodology Applied

Scientific EffectSynchronous rectification:

Implementation Method 3

resistance welding device... in order to provide a welding current for welding workpieces

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10112253B2Resistance welding device comprising a power source arranged on a welding gun

Publication Date: 2018.10.30 FRONIUS INT GMBH

AI summary

A resistance welding device includes a power source in order to provide a welding current for welding workpieces, a welding gun with two gun arms having one electrode each in order to impress the welding current into the workpieces. The power source includes a heavy-current transformer with at least one primary winding and at least one secondary winding with center tapping, a synchronous rectifier connected with the secondary winding and including circuit elements, and a circuit for actuating the circuit elements of the synchronous rectifier. For reduction of losses and improvement of efficiency, the power source is arranged at the welding gun and the power source includes at least four contacts forming a multi-point contacting, wherein two first contacts of one polarity are connected to one gun arm and two additional contacts of opposite polarity are connected to the other gun arm.