Quasi-Resonant Power Supply Valley Locking for Noise Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional quasi-resonant switching power supplies experience noise performance deterioration due to random valley switching, leading to abnormal noise, especially when the operation frequency approaches the upper or lower frequency limits, causing instability and inefficiency.
Innovation Solution
A valley locking mechanism is implemented in the quasi-resonant switching power supply, which includes a valley detector and a valley-locking controller to selectively lock switching cycles at specific voltage valleys, ensuring consistent operation frequency and reducing noise by alternately starting switching cycles at nth and (n+1)th valleys, thereby stabilizing the power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional quasi-resonant switching power supply operates at high frequency to reduce size, then power density increases, but noise performance deteriorates due to random valley switching
Solution Approach 1:
The patent applies periodic action by implementing valley locking that forces switching cycles to occur at regular periodic intervals (every nth or (n+1)th valley), converting the random irregular switching into a periodic pattern. This maintains the high-frequency operation needed for power density while eliminating the random noise through structured periodic switching behavior.
Solution Approach 2:
The patent uses dynamics by making the switching frequency adaptable - it can dynamically switch between different valley locking modes (different nth or (n+1)th valleys) depending on operating conditions. This allows the system to maintain optimal performance across varying load conditions while preserving the benefits of high-frequency operation.
2Volume of moving object
If operation frequency approaches frequency limits, then size reduction is achieved, but stability deteriorates due to random valley switching
Solution Approach 1:
By enforcing periodic switching at locked valleys, the system maintains stable operation even at frequency limits. The regular periodic pattern prevents the instability that would otherwise occur from random valley switching, allowing the power supply to operate at high frequencies for size reduction without sacrificing reliability.
Solution Approach 2:
The valley locking mechanism uses feedback from detecting voltage valleys to control switching timing. This feedback ensures that switching occurs at predictable, stable intervals, maintaining operational stability even when operating near frequency limits where stability would normally deteriorate.
3Loss of energy
If conventional power supply uses random valley switching, then switching loss is reduced, but electromagnetic interference increases
Solution Approach 1:
The patent resolves this contradiction by implementing periodic valley locking that maintains the energy-efficient random-like switching characteristics while imposing a periodic structure. This periodic pattern reduces electromagnetic interference by creating predictable, regular switching intervals, while still achieving low switching losses through continued operation in the resonant valley regions.
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 valley locking mechanism significantly improves noise performance by maintaining a stable operation frequency, reducing electromagnetic interference, and enhancing the overall efficiency of the quasi-resonant switching power supply.
Implementation Method 1
the transformer 110 also includes a parasitic leakage inductor 130 (e.g., Lleak), and the transistor 120 (e.g., S1) includes a parasitic capacitor 132 (e.g., Cp) between the drain terminal 122 and the source terminal 126 of the transistor 120. The quasi-resonant switching power supply 100 uses the primary winding 112 (e.g., Lp) and the parasitic capacitor 132 (e.g., Cp) to form an LC resonant cavity.
Implementation Method 2
When the demagnetization process of the primary winding 112 (e.g., Lp) is completed, the voltage (e.g., VDEM) drops to a low magnitude, and the primary winding 112 (e.g., Lp) and the parasitic capacitor 132 (e.g., Cp) undergo free oscillation.
Data Source
AI summary
Controller and method for a quasi-resonant switching power supply. For example, a controller for a quasi-resonant switching power supply includes: a valley detector configured to receive a voltage signal, detect one or more voltage valleys of the voltage signal in magnitude, and generate a detection signal representing the detected one or more voltage valleys; a valley-locking controller configured to receive one or more signals, generate a mode control signal that indicates a selected valley-locking mode based at least in part on the one or more signals, select from the detected one or more voltage valleys, one or more valleys that correspond to the selected valley-locking mode, and generate a valley control signal indicating the one or more selected valleys; and a gate driver configured to generate a drive signal based on at least information associated with the valley control signal.