LLC Resonant Converter Feedforward Ripple Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LLC resonant converters face challenges in effectively suppressing output voltage ripples due to the difficulty in balancing stability and gain in existing feedback control methods, which can lead to unstable performance or equipment damage.
Innovation Solution
The implementation of a feedforward correction mechanism using a feedforward controller to generate a signal based on the input voltage, which is used to control the operating frequency of the chopper in the LLC resonant converter, thereby counteracting the effect of input ripples on the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If feedback control is used to increase open-loop gain to reduce output ripples, then output ripple reduction is achieved to some degree, but stability deteriorates due to the difficulty in making a tradeoff between stability and high gain
Solution Approach 1:
The patent applies preliminary action by using a feedforward controller to detect input voltage ripples before they affect the output, and proactively generates a compensating signal to counteract their effect. This prevents the ripples from propagating through the system rather than reacting to them after they cause instability, thus achieving ripple suppression without compromising stability.
2Object-affected harmful factors
If high open-loop gain is implemented to suppress output ripples, then ripple reduction is improved, but the tradeoff between stability and high gain becomes difficult to manage
Solution Approach 1:
The patent segments the control function into two independent parts: a feedforward controller that handles ripple suppression by detecting input voltage variations, and a feedback controller that maintains system stability. This segmentation allows each controller to be optimized for its specific function without the tradeoff constraints that plague a single high-gain feedback system, simplifying overall control complexity.
Data Source
AI summary
The present disclosure discloses an LLC resonant converter and a method for suppressing ripples in output voltage of the LLC resonant converter. The LLC resonant converter comprises: a half-bridge or full-bridge chopper having a driving circuit, an inductance-capacitance series resonant network coupled to the chopper, an isolation transformer coupled to the resonant network, and a rectification and filtering circuit coupled to the isolation transformer; a feedforward controller coupled to generate a feedforward signal based on an input voltage; and a controlled oscillator coupled to receive the feedforward signal from the feedforward controller and to control an operating frequency of the chopper via the driving circuit based on the feedforward signal. Thus, a feedforward correction is provided for the LLC resonant converter, so that ripples in a DC output voltage of the LLC resonant converter are reduced.