Resonant Converter Synchronous Rectification Control Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resonant converters with synchronous rectification face challenges in maintaining efficient operation across varying load conditions due to propagation delays and inconsistent zero current crossing points, leading to inefficiencies and voltage spikes.
Innovation Solution
A resonant converter system with a synchronous rectification control circuit that generates a weighted turn-off signal by comparing a sensed current with a reflection signal and a reference voltage, ensuring the rectifying switch turns off at the zero crossing point, thereby maintaining efficiency across different loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If synchronous rectification technology is applied to resonant converters, then turn-on loss is reduced and efficiency is improved, but propagation delay causes inconsistent zero current crossing points leading to voltage spikes and inefficiencies
Solution Approach 1:
The patent applies preliminary action by generating the turn-off signal for the synchronous rectifying switch based on the zero current crossing point detection before the actual current reaches zero. The control circuit detects the zero current crossing point and generates a turn-off signal that accounts for the propagation delay, ensuring the switch turns off at the correct timing. This preliminary signaling approach compensates for the propagation delay and maintains consistent zero current crossing points across varying load conditions.
2Device complexity
If fixed threshold comparison method is used for zero current crossing detection, then control circuit is simple, but inconsistent zero crossing points occur under varying load conditions causing inefficiency
Solution Approach 1:
The patent applies dynamics by making the comparison threshold variable instead of fixed. The control circuit dynamically adjusts the comparison threshold based on the detected zero current crossing point and the propagation delay characteristics. This dynamic threshold adjustment ensures that the turn-off signal is generated at the correct timing under varying load conditions, maintaining consistent zero current crossing points and high rectification efficiency without requiring overly complex circuitry.
3Device complexity
If turn-off signal is generated without compensating for propagation delay, then control is simple, but voltage spikes occur due to inconsistent zero crossing points
Solution Approach 1:
The patent applies feedback by using the detected zero current crossing point information to adjust the turn-off signal generation timing. The control circuit monitors the actual current waveform, detects the zero current crossing point, and uses this feedback information to generate a turn-off signal that compensates for propagation delay. This feedback mechanism ensures that the synchronous rectifying switch turns off at the correct timing, preventing voltage spikes and maintaining stable operation under varying load conditions.
Data Source
AI summary
The configurations of a resonant converter system and a controlling method thereof are provided. The proposed resonant converter system includes a resonant converter receiving an input voltage for outputting an output voltage, a rectifying device having a first rectifying switch and a synchronous rectification control circuit coupled to the resonant converter and including a signal generation apparatus generating a weighted turn-off signal to turn off the first rectifying switch at a zero crossing point of a first current flowing through the first rectifying switch.