Capacitive Welder Circuit Using Solid-State Isolation
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Solution Overview
Problem
Conventional capacitive discharge welders rely on expensive, heavy, and space-consuming transformers for electrical isolation, which is undesirable in terms of cost, weight, and size efficiency.
Innovation Solution
A capacitive discharge welder circuit utilizing silicon or other solid-state switches to electrically isolate sections without a transformer, incorporating a charge section, capacitor section, and weld section with safety circuits for enhanced safety and efficiency, including optical isolators and a microcontroller for monitoring and fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is used for electrical isolation in a capacitive discharge welder, then electrical isolation between sections is achieved, but the device becomes expensive, heavy, and space-consuming
Solution Approach 1:
The patent replaces the traditional transformer-based electrical isolation system with solid-state electronic isolation using opto-isolators and opto-couplers. These optical components transmit control signals through light rather than direct electrical connection, eliminating the need for heavy magnetic cores and windings while achieving the same galvanic isolation function.
Solution Approach 2:
The invention changes the isolation mechanism from electromagnetic transformation to optical signal transmission. By converting control signals into light pulses that traverse an optical path between isolated circuits, the system achieves electrical isolation without the physical bulk and weight of transformers, reducing both mass and spatial footprint.
2Reliability
If a transformer is used for electrical isolation in a capacitive discharge welder, then electrical isolation between sections is achieved, but the device becomes expensive
Solution Approach 1:
The patent replaces the traditional transformer-based electrical isolation system with solid-state electronic isolation using opto-isolators and opto-couplers. These optical components transmit control signals through light rather than direct electrical connection, eliminating the need for heavy magnetic cores and windings while achieving the same galvanic isolation function.
Solution Approach 2:
The invention employs inexpensive solid-state opto-isolator components that are mass-producible and replace costly transformers. These optical isolators are compact, solid-state devices that provide adequate isolation for control circuits at a fraction of the cost of traditional transformer-based isolation systems.
3Reliability
If a transformer is used for electrical isolation in a capacitive discharge welder, then electrical isolation between sections is achieved, but the device occupies a large amount of space
Solution Approach 1:
The patent replaces the traditional transformer-based electrical isolation system with solid-state electronic isolation using opto-isolators and opto-couplers. These optical components transmit control signals through light rather than direct electrical connection, eliminating the need for heavy magnetic cores and windings while achieving the same galvanic isolation function.
Solution Approach 2:
The invention integrates multiple isolation functions into compact opto-isolator packages that can be mounted on standard circuit boards. The optical isolators are small enough to be nested within the existing circuit board layout, eliminating the need for separate transformer assemblies and significantly reducing the overall device footprint.
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 solution provides a cost-effective, lightweight, and compact welder that safely isolates users and components, preventing electrocution and ensuring proper operation by disconnecting power in case of faults, while allowing efficient welding operations.
Implementation Method 1
The first optical isolator has a first isolator input and a first isolator output. The first isolator input is coupleable to the resistive element at a second node. The first isolator output is coupleable to a power input of a solid state switch to be tested.
Data Source
AI summary
A weld circuit for use in a welder is provided. The weld circuit comprises a charge section, a capacitor section, and a weld section. The charge section includes a first plurality of solid state switches, e.g., silicon controlled rectifiers (charge SCRs), the capacitor section includes a weld capacitor, and the weld section includes a second plurality of solid state switches, e.g., silicon controlled rectifiers (weld SCRs). The charge SCRs form a bridge between the lines in the charge circuit. One weld SCR is coupled to a first weld terminal and the other weld SCR is coupled to a second weld terminal. The charge and weld SCRs isolate the charge section, the capacitor section, and the weld section from each other. The weld circuit is coupleable to a safety circuit that comprises a resistor, a microcontroller, and optical isolators. When the optical isolators are enabled, the microcontroller monitors a current flowing through the resistor.