Resonant Converter Switching Control for Through-Current Prevention
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Solution Overview
Problem
Existing resonant converter circuits fail to prevent off-resonance when the resonance current becomes small, leading to through-currents from the power supply to the ground.
Innovation Solution
A switching control circuit that detects the difference between the timing of switching device turn-on and resonance current polarity reversal, outputting a driving signal with a preset minimum frequency when this difference becomes small, to maintain the resonant condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switching frequency is allowed to vary freely in response to output voltage, then converter can adapt to load changes, but switching frequency may enter capacitive load region causing through-current
Solution Approach 1:
The patent implements feedback control by continuously monitoring the timing difference between switching device turn-on and current polarity reversal. When this timing difference indicates approaching capacitive load region, the system adjusts switching frequency to maintain safe operating margins, preventing through-current while adapting to load changes
Solution Approach 2:
The patent applies preliminary anti-action by detecting timing differences that indicate the system is approaching the capacitive load region, and preemptively adjusting the switching frequency before the system actually enters the off-resonance state. This prevents through-current by acting in advance of the harmful condition
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
Effectively prevents off-resonance by ensuring the switching frequency remains within the resonant range, even when resonance currents are low, thereby preventing through-currents.
Implementation Method 1
resonance current of a resonant converter
Data Source
AI summary
A switching control circuit controls switching of a switching device, which controls a resonance current of a resonant converter, with a frequency corresponding to an output voltage of the resonant converter. The switching control circuit includes a detection circuit configured to detect a difference between a first timing at which the switching device is turned on and a second timing at which a polarity of the resonance current reverses, and a signal output circuit configured to output a driving signal with a preset minimum frequency, responsive to the difference becoming so small as to satisfy a predetermined condition.