Phase Shifted Double Forward Converter Control
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Solution Overview
Problem
Existing welding-type power supplies face inefficiencies in handling dynamic load requirements due to oversized components, leading to undesirable disturbances in the welding arc and potential transformer saturation, especially during phase shifted operations, which can result in arc outages or voltage droops.
Innovation Solution
A phase shifted double forward (PSDF) converter system with advanced control mechanisms that adjust duty cycles, phase shifting, and converter operation modes to optimize component usage and minimize losses, including disabling converters during low current conditions to maintain consistent pulse widths and reduce transformer core reset time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If components are oversized to handle short dynamic loads, then the power supply can accommodate extreme requirements, but the circuit becomes inefficient when operating at average conditions
Solution Approach 1:
The patent implements dynamic component configuration by selectively enabling or disabling converter circuits based on load conditions. The system transitions from a static component configuration to a dynamic one where the active circuit topology changes with operating conditions, allowing efficient operation at both average and peak loads without requiring oversized components for all conditions.
Solution Approach 2:
The system changes operational parameters by switching between different converter configurations (single converter vs. dual converter parallel operation). This parameter change allows the power supply to adapt its effective component size and capacity based on the instantaneous load requirements, optimizing efficiency across the full operating range.
2Power
If phase shifting is increased to provide higher output voltage during dynamic conditions, then the power supply can meet transient requirements, but control loss and transformer saturation occur
Solution Approach 1:
The patent segments the power conversion function into two separate forward converter circuits that can operate independently or in parallel. This segmentation allows the system to provide high voltage capability through controlled parallel operation without requiring excessive phase shifting, thereby maintaining control stability and preventing transformer saturation.
Solution Approach 2:
The system dynamically adjusts the operational mode between single converter and dual converter parallel operation based on load conditions. This dynamic switching provides the necessary voltage capability during transient conditions while maintaining stable control and avoiding transformer saturation by not relying on excessive phase shifting.
3Loss of energy
If converters operate in parallel to share load current, then efficiency is improved during average conditions, but coordination complexity and control difficulty increase
Solution Approach 1:
The patent implements feedback control mechanisms that monitor the operational state and load conditions, automatically determining when to switch between single converter and dual converter parallel operation. This feedback-based control simplifies the coordination complexity by using automated decision-making based on measurable parameters rather than complex manual coordination.
Solution Approach 2:
The system changes the operational parameter from single converter mode to dual converter parallel mode based on load conditions. This parameter change enables efficiency improvement through current sharing while the automated control logic manages the coordination complexity, making the transition seamless and easier to control.
4Power
If duty cycle is increased to meet higher power demands, then the output voltage and current can be increased, but transformer core reset time is insufficient leading to saturation
Solution Approach 1:
The patent segments the power delivery function across two separate forward converter circuits, each with its own transformer. This segmentation allows each transformer to operate at a lower duty cycle with adequate reset time, while the combined output of both converters meets the high power demand, thus avoiding transformer saturation.
Solution Approach 2:
The system merges the outputs of two forward converter circuits operating in parallel to achieve high power capability. Each converter operates at a moderate duty cycle that allows sufficient transformer core reset time, and their combined output meets the high power demands without requiring any single transformer to operate at dangerously high duty cycles.
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 enables efficient handling of both average and dynamic load requirements, reducing disturbances and transformer saturation, while maintaining efficient operation by optimizing duty cycles and phase shifting to ensure consistent power delivery and wider operational windows.
Implementation Method 1
a first forward converter circuit (24) and a second forward converter circuit (26) that combine to provide an output (30)
Data Source
AI summary
A method and apparatus for providing welding type power includes a phase shifted double forward converter having a first and second converter and a controller. The controller includes a pwm module that sets the pwm timing signals. The pwm module includes a phase shift module that has a leading edge adjusted output and a trailing edge adjusted output responsive to the output load. The phase shift module also includes a duty cycle offset module and/or a Dmax module that is responsive to the output load current. The pwm module includes a disabling module responsive to at least one of the output current and output voltage that disables one of the first and second converters.