Quasi-Resonant Switching Converter Controller with Dynamic Valley Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switching converters with quasi-resonant control often generate audio noise and discontinuous output power due to valley switching between adjacent voltage valleys, which affects efficiency and performance.
Innovation Solution
A controller circuit comprising an error amplifying circuit, a comparison circuit, a valley detection circuit, a valley selection circuit, and a frequency control circuit is used to generate a compensation signal, pulse frequency modulation signal, and frequency control signal, which helps in selecting a target valley number and controlling the switching frequency to minimize noise and ensure continuous output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If valley switching control is used to reduce switching loss, then switching efficiency is improved, but audio noise and discontinuous output power are generated due to valley jumping between adjacent valleys
Solution Approach 1:
The patent implements dynamic valley selection by introducing a valley selection circuit that dynamically chooses between adjacent valleys based on real-time operating conditions. The circuit generates a valley selection signal that adapts the switching timing to prevent valley jumping, thereby eliminating audio noise while maintaining the efficiency benefits of quasi-resonant control.
Solution Approach 2:
The patent employs feedback mechanisms through error amplifying circuits and control circuits that monitor the switching process and adjust the valley selection in real-time. The feedback loop detects valley jumping conditions and corrects the switching timing to maintain stable operation, preventing audio noise generation.
2Loss of energy
If valley switching control is used to reduce switching loss, then switching efficiency is improved, but output power discontinuity occurs due to valley jumping between adjacent valleys
Solution Approach 1:
The valley selection circuit dynamically adjusts the switching valley selection based on real-time operating conditions, ensuring continuous and stable output power. By adaptively choosing the appropriate valley for switching, the circuit prevents discontinuities in power delivery while maintaining the efficiency advantages of quasi-resonant control.
Solution Approach 2:
Feedback control circuits monitor output power stability and adjust valley selection to prevent discontinuities. The error amplifying circuit detects deviations from desired operation and corrects valley jumping, ensuring continuous power delivery while maintaining low switching losses.
3Device complexity
If fixed frequency control is used, then control simplicity is maintained, but switching loss is high and efficiency varies with load or input voltage
Solution Approach 1:
The patent implements variable frequency control through a frequency control circuit that dynamically adjusts the switching frequency based on load and input voltage conditions. This dynamic adjustment reduces switching losses across different operating points while maintaining manageable control complexity through systematic circuit design.
4Loss of energy
If variable frequency control is used to reduce switching loss, then switching efficiency is improved, but control complexity increases
Solution Approach 1:
The patent divides the control function into separate modular circuits: error amplifying circuit, valley detection circuit, valley selection circuit, and frequency control circuit. This segmentation allows each circuit to perform a specific function, reducing overall control complexity while achieving variable frequency control for reduced switching losses.
Solution Approach 2:
The patent implements dynamic control through dedicated circuits that automatically adjust switching parameters based on operating conditions. The valley selection circuit and frequency control circuit work together to dynamically optimize switching timing and frequency, reducing switching losses without requiring overly complex control logic.
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
The solution effectively reduces audio noise and ensures continuous output power by stabilizing the switching frequency, thereby improving the efficiency and performance of the switching converter across varying load and input voltage conditions.
Implementation Method 1
When a current sense signal Ics indicative of the current flowing through the energy storage component decreases to zero, the energy storage component resonates with the parasitic capacitance of the switch
Data Source
AI summary
A controller of a switching converter includes an error amplifying circuit, a first comparison circuit, a valley detection circuit, a valley selection circuit and a frequency control circuit. The error amplifying circuit generates a compensation signal based on the difference between a reference signal and a feedback signal. The first comparison circuit compares the compensation signal with a modulation signal and generates a pulse frequency modulation signal. The valley detection circuit detects valleys of a resonant voltage of the switching converter and generates a valley pulse signal. The valley selection circuit generates a valley enable signal corresponding to a target valley number based on the pulse frequency modulation signal and the valley pulse signal. The frequency control circuit generates a frequency control signal to control the switching frequency of the first switch based on the valley enable signal and the valley pulse signal.