Phase-Shift Full-Bridge Converter Clamping for Secondary Surge Control
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Solution Overview
Problem
Traditional full-bridge phase-shift converters experience high-voltage oscillations due to secondary-side leakage inductances, leading to surge voltages that exceed component ratings and generate electromagnetic interference, necessitating the use of high-voltage components which increase costs and reduce efficiency.
Innovation Solution
A full-bridge phase-shift converter with voltage clamping, incorporating a transformer, synchronous rectifying switches, diodes, a capacitor for clamping voltage storage, and an energy-releasing unit (DC step-down converter or low-dropout regulator) that detects and releases energy to reduce clamping voltage when it exceeds set thresholds, thereby suppressing surge voltages without needing high-voltage components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If components with higher voltage ratings are used to withstand surge voltages, then the reliability of the converter is improved, but the cost and power conversion efficiency deteriorate
Solution Approach 1:
The patent captures the harmful surge energy generated by leakage inductance and redirects it through a rectification circuit to charge a capacitor, converting the harmful voltage spike into useful charged energy that can be fed back to the output, thereby improving efficiency while maintaining reliability
Solution Approach 2:
The patent introduces a capacitor as an intermediary energy storage element between the surge-generating leakage inductance and the output load, along with clamping circuits that activate only during surge conditions. This intermediary structure isolates the main power conversion path from the surge effects, allowing standard components to be used while maintaining reliability
2Reliability
If components with higher voltage ratings are used to withstand surge voltages, then the reliability of the converter is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the surge suppression function from the main power components and implements it through a separate, dedicated circuit branch with the capacitor and clamping diodes. This allows the main power path to use simple, standard components while the extracted suppression circuit handles the surge protection function
Solution Approach 2:
The patent employs simple, inexpensive components (capacitors, diodes, resistors) in the surge suppression circuit that are activated only temporarily during surge events. These components are much cheaper than high-voltage rated power components and can be easily replaced if needed
3Reliability
If components with higher voltage ratings are used to withstand surge voltages, then the reliability of the converter is improved, but the heat dissipation problem worsens
Solution Approach 1:
The patent converts the harmful surge energy that would otherwise be dissipated as heat into useful charged energy stored in the capacitor. This energy can then be delivered to the output load, transforming what would be wasted heat into useful work and reducing overall thermal load
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 effectively suppresses surge voltages by releasing energy stored in the capacitor, maintaining power conversion efficiency and preventing electromagnetic interference, without the need for high-voltage components, thus reducing costs and heat dissipation issues.
Implementation Method 1
the leakage inductances LLkS1, LLkS2 and the parasitic capacitances of the first synchronous rectifying switch QS1 and the second synchronous rectifying switch QS2 will occur high-voltage oscillation to generate surge voltages
Implementation Method 2
The capacitor is coupled to the clamping node, and provides a clamping voltage
Implementation Method 3
The energy-releasing unit is coupled to the capacitor in parallel, and converts the clamping voltage into an output voltage
Implementation Method 4
The transformer includes a primary-side winding and a secondary-side winding
Data Source
AI summary
A full-bridge phase-shift converter with voltage clamping includes a transformer, a primary-side circuit, and a secondary-side circuit. The secondary-side circuit includes a first synchronous rectifying switch, a second synchronous rectifying switch, an output inductor, a plurality of diodes, a capacitor, an energy-releasing unit, and an output capacitor. The capacitor provides a clamping voltage. The energy-releasing unit is coupled to the capacitor in parallel, and converts the clamping voltage into an output voltage. The output capacitor is coupled to the energy-releasing unit in parallel, and provides the output voltage.