Full-Bridge DC-DC Converter Control for Soft Switching
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Solution Overview
Problem
Conventional control methods for DC-DC converters, such as phase-shifted full-bridge converters, result in hard-switching of switching elements during discontinuous operation, leading to increased electrical losses and reduced component lifespan.
Innovation Solution
A control method for DC-DC converters that employs soft-switching of switching elements by controlling diagonal branches on both the primary and secondary sides of the converter, using a transformer short-circuiting strategy to minimize electrical losses and protect switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional control methods are used for DC-DC converters during discontinuous operation, then the converter can operate in discontinuous conduction mode, but switching elements are hard-switched resulting in increased electrical losses
Solution Approach 1:
The control method performs preliminary action by ensuring that the voltage across switching elements is reduced to zero or near-zero before switching occurs. This is achieved through specific sequencing of switch operations and transformer short-circuiting actions that prepare the circuit state in advance, enabling soft-switching conditions during discontinuous conduction mode operation.
Solution Approach 2:
The invention changes the voltage parameter across switching elements during the switching transition. By dynamically controlling the circuit state and transformer connections, the voltage parameter is transformed from a high-value state (during normal operation) to a zero or near-zero state (during switching), enabling soft-switching and reducing electrical losses.
2Ease of operation
If hard-switching is performed on switching elements during discontinuous operation, then the converter maintains simple control, but electrical losses increase and component stress increases
Solution Approach 1:
The transformer serves as an intermediary element in the soft-switching process. By controlling the transformer connections and introducing intermediate switching states, the invention mediates between the simple control requirement and the need for reduced electrical losses, achieving soft-switching through the transformer's magnetic coupling and energy transfer characteristics.
3Productivity
If switching elements are controlled while voltage is present across them, then the converter operates with standard switching control, but electrical losses increase and switching element loading increases
Solution Approach 1:
The control method performs preliminary action by ensuring that the voltage across switching elements is reduced to zero or near-zero before switching occurs. This is achieved through specific sequencing of switch operations and transformer short-circuiting actions that prepare the circuit state in advance, enabling soft-switching conditions during discontinuous conduction mode operation.
Solution Approach 2:
The invention employs periodic action through oscillatory switching sequences that create periodic voltage and current waveforms. By timing the switching operations to occur at specific points in these periodic waveforms (when voltage is naturally zero or near-zero), the method achieves soft-switching and reduces electrical losses while maintaining productive energy transfer.
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 method reduces electrical losses and minimizes loading on switching elements, extending their lifespan without requiring additional components, and enables efficient energy transfer.
Implementation Method 1
A transformer is provided between the primary-side full-bridge and the secondary-side full-bridge
Implementation Method 2
the primary side of the transformer is short-circuited by means of the primary-side full-bridge
Data Source
AI summary
A method for controlling a DC-DC converter having a primary-side full-bridge, a secondary-side full-bridge and a transformer, which is arranged between the primary-side full-bridge and the secondary-side full-bridge, wherein the method includes controlling a diagonal branch in the secondary-side full-bridge while the primary side of the transformer is short-circuited by means of the primary-side full-bridge and controlling a diagonal branch in the primary-side full-bridge.