Isolated Power Converter Resonance Control for Soft Switching
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Solution Overview
Problem
Existing power conversion systems with switching elements on the secondary side of an isolation transformer complicate the circuit configuration and control, making soft switching difficult to achieve.
Innovation Solution
A resonance circuit is connected to the output side of the isolation transformer, allowing a switching element to be turned on during a period when current flows from the low potential side to the high potential side via the transformer, enabling soft switching with simpler control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching elements are provided on the secondary side of the isolation transformer for soft switching, then soft switching can be achieved, but the circuit configuration becomes complicated and control becomes complicated
Solution Approach 1:
The invention extracts the soft switching function from the secondary side switching elements and relocates it to the primary side. By removing the switching elements from the secondary side and implementing soft switching control only on the primary side switching elements (Q1-Q4), the circuit configuration is simplified while maintaining the soft switching capability. The control unit generates gate signals to turn on primary side switching elements during periods when current flows through the resonance circuit, achieving soft switching without secondary side switching elements.
Solution Approach 2:
The resonance circuit on the secondary side serves multiple functions: it provides the current path necessary for soft switching and simultaneously acts as a smoothing means using the output capacitor, leakage inductance of the isolation transformer, and output capacitor. This multi-functionality eliminates the need for separate soft switching components on the secondary side, reducing overall circuit complexity.
2Reliability
If switching elements are provided on the secondary side of the isolation transformer for soft switching, then soft switching can be achieved, but control becomes complicated
Solution Approach 1:
The invention extracts the control complexity from secondary side switching and concentrates it on the primary side. The control unit only needs to monitor and control primary side switching elements (Q1-Q4), generating gate signals based on current flow through the resonance circuit. This eliminates the need for complex secondary side control logic and simplifies the overall control architecture while maintaining soft switching functionality.
3Device complexity
If a resonance circuit is connected to the output side of the isolation transformer, then soft switching can be realized with simpler control, but additional components are required
Solution Approach 1:
The resonance circuit components (output capacitor, leakage inductance of isolation transformer) serve dual purposes: they form the resonance circuit necessary for soft switching and simultaneously function as smoothing means for the power conversion. This multi-functionality justifies the addition of the resonance circuit by eliminating the need for separate smoothing components, making the overall component count reasonable while achieving simpler control.
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
This approach allows for the realization of soft switching with relatively simple control, reducing switching losses and improving power conversion efficiency.
Implementation Method 1
A resonance circuit is connected to the output side of the isolation transformer, allowing a switching element to be turned on during a period when current flows from the low potential side to the high potential side via the transformer
Implementation Method 2
an input side and an output side are connected via an isolation transformer
Data Source
AI summary
The present disclosure includes a conversion circuit (10) having a switching element and converting DC voltage into AC voltage by switching operation of the switching element, an isolation transformer (3) for which an input side is connected to the conversion circuit (10), a rectifier circuit (4) connected to an outside of the isolation transformer (3), a resonance circuit connected to the output side of the isolation transformer (3), and a control circuit (100) for controlling the switching element, wherein the control circuit (100) turning on the switching element in a period when current flowing through resonance circuit flows from a low potential side terminal to a high potential side terminal of the switching element via the isolation transformer (3).