Synchronous Rectification Control for Resonant Power Supply
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Solution Overview
Problem
Existing synchronous rectification control methods for resonant power supplies fail to effectively manage the timing of turning off the synchronous rectification switch, leading to increased losses and distortion of resonant current, which affects the efficiency and safety of the system.
Innovation Solution
A method that involves dual-ended detection of the voltage across the body diode of the synchronous rectification switch to calculate the resonant frequency and determine the maximum conduction width, ensuring optimal operation by adjusting the timing of switch conduction and turning off the switch at a zero-current condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the synchronous rectification switch is turned off earlier than the optimal turned-off point, then the resonant current distortion is avoided, but the losses of the synchronous rectification switch increase
Solution Approach 1:
The patent employs feedback control by detecting the voltage waveform across the body diode of the synchronous rectification switch and using this information to dynamically adjust the turn-off timing. The control method calculates the resonant frequency based on the detected voltage waveform and determines the optimal turn-off point, creating a closed-loop system that adapts to varying operating conditions and minimizes both losses and resonant current distortion.
Solution Approach 2:
The patent changes the timing parameter of the synchronous rectification switch turn-off based on the detected voltage waveform characteristics. By calculating the resonant frequency from the voltage waveform and adjusting the turn-off timing accordingly, the system optimizes the conduction width parameter dynamically, resolving the contradiction between minimizing losses and preventing resonant current distortion.
2Loss of energy
If the synchronous rectification switch is turned off later than the optimal turned-off point, then the efficiency is improved, but the resonant current becomes distorted
Solution Approach 1:
The control method uses feedback from the voltage waveform detection to precisely determine the optimal turn-off point. By continuously monitoring the voltage across the body diode and calculating the resonant frequency, the system adjusts the turn-off timing to achieve the maximum possible efficiency while preventing resonant current distortion, thus resolving the contradiction between efficiency improvement and maintaining safe operation.
Solution Approach 2:
The patent implements dynamic adjustment of the synchronous rectification switch turn-off timing based on real-time voltage waveform detection. The conduction width is not fixed but dynamically optimized according to the detected resonant frequency and voltage characteristics, allowing the system to achieve high efficiency while maintaining safe operation across varying load conditions.
3Loss of energy
If the conduction width of the synchronous rectification switch is increased, then the converter efficiency is improved, but the resonant frequency distortion occurs
Solution Approach 1:
The patent dynamically changes the conduction width parameter based on the detected voltage waveform and calculated resonant frequency. By adjusting the conduction width to match the optimal value derived from voltage waveform analysis, the system maximizes converter efficiency while preventing resonant frequency distortion, effectively resolving the contradiction between efficiency improvement and frequency accuracy.
4Reliability
If the conduction width of the synchronous rectification switch is decreased, then the resonant current safety is improved, but the switch losses increase
Solution Approach 1:
The patent uses feedback control to dynamically adjust the conduction width based on real-time voltage waveform detection. By continuously monitoring the voltage across the body diode and adjusting the turn-off timing accordingly, the system maintains the narrowest safe conduction width that prevents resonant current distortion while minimizing switch losses, resolving the contradiction between safety and efficiency.
Data Source
AI summary
A synchronous rectification control method for a resonant power supply includes steps as follows. First, setting an initial conduction width of a synchronous rectification switch, which is less than a maximum conduction width. Afterward, detecting a voltage waveform across two ends of a body diode of the synchronous rectification switch. Afterward, calculating a resonant frequency according to the voltage waveform. Finally, determining the maximum conduction width of the synchronous rectification switch.