Soft Switching Converter Magnetizing Current Steering
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Solution Overview
Problem
Traditional pulse width modulation (PWM) controlled converters face challenges with hard switching in the primary and reverse recovery problems in the secondary, with few solutions addressing the latter effectively, leading to significant switching losses, especially at high output voltages.
Innovation Solution
The design and control method for converters with a transformer and output choke, where the magnetizing current exceeds the output choke current at its lowest point, enabling soft transitions in all switching elements, and utilizing synchronous rectification with tailored frequency modulation to achieve zero voltage switching conditions across various converter topologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hard switching is used in the primary, then device complexity is reduced, but reverse recovery problems occur in the secondary
Solution Approach 1:
The patent applies preliminary action by ensuring that the magnetizing current is sufficiently high before switching events occur. This preliminary current condition enables the rectifier means to turn off naturally with zero or negative current, preventing reverse recovery problems before they can occur, while maintaining relatively simple switching control
Data Source
AI summary
A method is shown to create soft transition in selected topologies by controlling and designing the magnetizing current in the main transformer to exceed the output current at a certain point in the switching cycle.