Zero-Voltage and Quasi-Resonant Converter Control for Valley Jumping
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Solution Overview
Problem
Switching converters with quasi-resonant control face challenges such as audio noise, discontinuous output power, and increased switching losses at higher frequencies, hindering efficiency and power density.
Innovation Solution
A controller system for switching converters that incorporates a transformer with a primary and auxiliary switch, utilizing an output feedback circuit, hysteresis feedback circuit, comparison circuits, and a turn-on control circuit to achieve zero-voltage switching and quasi-resonant switching by dynamically adjusting the target locked valley number for optimal switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching frequency is increased to meet higher power density demand, then the power density is improved, but the switching losses of the power switch increase proportionally
Solution Approach 1:
The patent applies parameter changes by transitioning from hard switching to soft switching techniques. Specifically, it implements zero-voltage switching (ZVS) for the primary switch and quasi-resonant switching for the secondary switch, changing the switching characteristics to reduce losses while maintaining high frequency operation for improved power density
2Loss of energy
If quasi-resonant control is used to reduce switching loss, then the switching loss is reduced, but audio noise and discontinuous output power are generated due to valley jumping
Solution Approach 1:
The patent employs feedback mechanisms through output feedback circuits and hysteresis feedback circuits that monitor the switching process and provide feedback signals to the control circuits. This feedback enables dynamic adjustment of switching parameters to maintain stable operation, prevent valley jumping, and eliminate audio noise while preserving the low switching loss benefits of quasi-resonant control
3Loss of energy
If valley switching is used to reduce switching loss, then the switching loss is reduced, but the output power becomes discontinuous due to loop adjustment causing valley jumping
Solution Approach 1:
The patent applies dynamics by implementing dynamic valley locking mechanisms that adaptively track and lock onto the optimal valley points during switching operations. The control circuits dynamically adjust the switching timing based on real-time voltage and current conditions, ensuring continuous and stable output power while maintaining reduced switching losses through optimized valley switching
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 solution reduces switching losses, minimizes electromagnetic interference (EMI), and enhances efficiency by allowing zero-voltage switching of the primary switch while maintaining quasi-resonant switching, thereby improving overall converter performance.
Implementation Method 1
the energy storage component resonates with a parasitic capacitance of a power switch
Implementation Method 2
The output feedback circuit is configured to receive an output signal of the switching converter and generate an output feedback signal. The hysteresis feedback circuit is configured to generate a hysteresis feedback signal based on the output feedback signal.
Data Source
AI summary
A control method of a zero-voltage switching converter with quasi-resonant control, the converter has a first switch and second switch respectively coupled to a primary winding and an auxiliary winding. The control method is: generating a hysteresis feedback signal based on an output feedback signal indicative of an output signal of the converter; comparing the hysteresis feedback signal with a ramp signal and generating a first comparison signal; comparing the output feedback signal with the ramp signal and generating a second comparison signal; generating a target locked valley number based on a valley pulse signal indicative of valleys of a voltage drop across the second switch, the first and second comparison signals; generating a turning on control signal corresponding to the target locked valley number for the second switch; and providing a control signal to turn on the first switch after turning off the second switch.