LLC Resonant Converter Synchronous Rectifier Feedback Control
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Solution Overview
Problem
Existing resonant converters face inefficiencies due to switching losses and body diode conduction, which affect power density and efficiency in telecommunication network power systems.
Innovation Solution
A control mechanism for LLC resonant converters that detects the drain-to-source voltage of a synchronous rectifier, compares it with a threshold, and adjusts the switching frequency to maintain operation near the resonant frequency, preventing body diode conduction and achieving zero voltage and current switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching frequency is adjusted to maintain operation near resonant frequency, then efficiency is improved through zero voltage switching, but device complexity increases due to feedback control mechanism
Solution Approach 1:
The patent implements a feedback control mechanism that monitors the drain-to-source voltage of the synchronous rectifier and adjusts the switching frequency accordingly. The control circuit detects when the converter operates away from resonant frequency and modifies the switching frequency to return to the resonant point, ensuring zero voltage switching and maximum efficiency.
Solution Approach 2:
The synchronous rectifier's body diode conduction state serves as a natural indicator of resonant operation. The control mechanism uses this existing physical phenomenon without requiring additional sensors or complex measurement systems, allowing the system to self-regulate based on its own operational state.
2Power
If switching frequency is adjusted dynamically to prevent body diode conduction, then power density is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent dynamically changes the switching frequency parameter based on the detected operational state. By monitoring the drain-to-source voltage and detecting body diode conduction events, the system adjusts the switching frequency to maintain resonant operation, thereby optimizing power density without requiring extreme manufacturing precision.
Solution Approach 2:
The switching frequency is made dynamic rather than fixed, allowing the converter to adapt to changing load conditions and maintain optimal resonant operation. This dynamic adjustment enables the system to achieve high power density across varying operating points while tolerating normal manufacturing variations.
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 enhances the efficiency of LLC resonant converters by maintaining operation near the resonant frequency, reducing switching losses and improving power density and efficiency.
Implementation Method 1
LLC resonant converters are capable of reducing switching losses through zero voltage switching and/or zero current switching
Data Source
AI summary
A method comprises detecting a signal representing a drain-to-source voltage of a switch of a synchronous rectifier of an inductor-inductor-capacitor (LLC) resonant converter, comparing the signal with a predetermined threshold, generating a first logic state if the drain-to-source voltage is greater than the predetermined threshold, generating a second logic state if the drain-to-source voltage is less than the predetermined threshold and in response to the first logic state and the second logic state, adjusting a switching frequency of the LLC resonant converter such that the switching frequency moves back and forth across a boundary of body diode conduction, wherein a frequency difference between the switching frequency and a resonant frequency of the LLC resonant converter is less than or equal to one frequency adjustment step.