Balanced DC Bus for Arc Welder Power Supply

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Solution Overview

Problem

Welding-type power supplies face challenges in providing consistent output across varying input voltages and dynamic load conditions, leading to issues like switching losses, heat damage, and electromagnetic interference, and require extensive design and engineering for different output currents, making them complex and costly to manufacture.

Innovation Solution

A modular welding-type power supply system with a controller, preregulator, and output converter, featuring stacked boost circuits and inverter circuits, which can adapt to different input voltages and power levels, and includes bus voltage balancing and current balancing modules to optimize component efficiency and reduce unnecessary components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a welding power supply is designed for a single input voltage, then components can operate safely at that input level, but the power supply cannot provide consistent output across different input voltages

Engineering Contradiction:
Improvecomponent safetyVSAvoidinput voltage compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic input voltage detection system that automatically adjusts the operating parameters of power components based on the detected input voltage level. The controller monitors input voltage and dynamically reconfigures the power circuitry to maintain safe component operation while adapting to different voltage sources (115V, 230V, 460V, 575V).

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operating parameters of power components based on detected input voltage. When a higher voltage is detected, the controller adjusts component duty cycles, switching frequencies, and current limits to prevent component damage while maintaining proper output regulation across all supported input voltages.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If power supplies are designed for steady loads, then design is simplified, but welding's dynamic process with constantly changing variables leads to unpredictable output current and voltage

Engineering Contradiction:
Improvepower supply designVSAvoidoutput consistency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements comprehensive feedback control that continuously monitors output current and voltage, comparing them against reference values. The controller dynamically adjusts power component switching to maintain consistent output despite varying welding conditions such as arc length, electrode type, and workpiece characteristics.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system employs dynamic parameter adjustment where the controller continuously modifies operating parameters based on real-time welding conditions. This includes adaptive current limiting, dynamic duty cycle adjustment, and flexible switching frequency modulation to maintain stable output during the inherently dynamic welding process.

Inventive Principle:
Principle #15Dynamics

3Power

If welding power supplies are designed for high power output, then they can meet welding demands, but switching losses, line losses, heat damage, and electromagnetic interference increase

Engineering Contradiction:
Improveoutput powerVSAvoidswitching losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent employs high-frequency periodic switching of power components to achieve high power transfer efficiency. By switching at optimized frequencies and using pulse-width modulation, the system minimizes switching losses while delivering high power output. The periodic action allows for efficient energy transfer through the transformer and reduces cumulative losses.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically changes operating parameters including switching frequency and duty cycle to optimize efficiency at different power levels. The controller adjusts these parameters based on load conditions to minimize switching losses and heat generation while maintaining required output power levels.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If welding power supplies are designed for specific output currents, then they can be optimized for particular processes, but extensive design and testing is required for different output levels

Engineering Contradiction:
Improvedesign optimizationVSAvoiddesign variety
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent implements a universal power supply design with a configurable output current range (100-200 amps) that can serve multiple welding processes and applications. The system uses software-based current limiting and control algorithms that can be programmed for different welding processes (stick, TIG, MIG) without requiring hardware redesign, eliminating the need for extensive redesign and testing for each output level.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 modular system enables efficient handling of a range of inputs and outputs, reducing switching losses and component costs while maintaining balanced voltage sharing, thus providing a flexible and efficient welding power supply solution.

Implementation Method 1

A dual stacked boost pre-regulator power circuit and a dual stacked full bridge inverter circuit are disclosed.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The output converter receives the preregulated bus as a power signal and receives the output converter control output as a control input. The output converter provides a welding type power output, and includes at least one stacked inverter circuit.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3215297B1Method and apparatus including a balanced DC bus for providing power in an arc welder
Publication Date: 2020.12.02 ILLINOIS TOOL WORKS INC
  • EP3215297B1 patent drawingFigure 1
  • EP3215297B1 patent drawingFigure 2
  • EP3215297B1 patent drawingFigure 3~4

AI summary

A welding-type power supply includes a controller, bus (that can, but need not be preregulated), and an output converter. The controller has a preregulator control output and an output converter control output. The controller may receive bus feedback indicative of a plurality of bus voltages. A bus voltage balancing module in the converter includes a scaled correction module responsive to the bus feedback signal, and the converter control output is responsive to the bus voltage balancing module. The controller may receive load feedback indicative of a load output, have a bus voltage balancing module that includes a load proportional gain module responsive to the load.