LLC Resonance Converter Control for Light-Load Display Power
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Solution Overview
Problem
Existing LLC resonance converters experience efficiency drops at light loads due to limited frequency operation range, leading to increased noise, reduced power density, and higher costs with complex structures.
Innovation Solution
A display device with an LLC resonance converter that adjusts resonance frequency based on load conditions, using a control unit to change resonance frequency according to power consumption, screen mode, or set brightness, incorporating sub-resonance inductance and capacitance to maintain high efficiency across varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching frequency is reduced to improve light load efficiency, then efficiency is improved, but power density decreases and magnetic component size increases
Solution Approach 1:
The patent applies dynamics by making the resonance frequency adjustable rather than fixed. The LLC resonance converter dynamically changes its operating resonance frequency based on load conditions, allowing it to maintain high efficiency across different load levels without requiring large magnetic components designed for worst-case scenarios.
Solution Approach 2:
The patent changes the resonance frequency parameter of the LLC resonance converter to optimize performance. By adjusting the resonance frequency according to load conditions, the system achieves high efficiency at light loads without needing to reduce switching frequency, thereby avoiding increased magnetic component size.
2Loss of energy
If burst operation is used to improve light load efficiency, then efficiency is improved, but audible noise increases
Solution Approach 1:
The patent changes the resonance frequency parameter to optimize performance. By adjusting the resonance frequency according to load conditions, the system achieves high efficiency at light loads without needing to reduce switching frequency, thereby avoiding increased magnetic component size.
Solution Approach 2:
The patent uses periodic action by implementing burst operation mode where the converter operates in intermittent cycles. The control unit enables burst operation when load is light, allowing the converter to switch on and off in periodic bursts, which reduces energy loss while maintaining acceptable noise levels through proper frequency management.
3Speed
If a full bridge is used instead of half bridge to reduce operation current, then operation current is reduced, but cost increases and structure becomes complicated
Solution Approach 1:
The patent changes the resonance frequency parameter to optimize performance. By adjusting the resonance frequency according to load conditions, the system achieves high efficiency at light loads without needing to reduce switching frequency, thereby avoiding increased magnetic component size.
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 allows for efficient operation at light loads by adjusting resonance frequency, minimizing efficiency loss, noise, and structural complexity while maintaining power density and reducing costs.
Implementation Method 1
LLC resonance converter has an advantage of achieving high efficiency and high power density by performing a zero voltage switching (ZVS) operation in a wide frequency range
Data Source
AI summary
The present disclosure relates to a display device for alleviating an efficiency reduction problem at a light load, and an operating method therefor, the display device comprising: a display; a power supply unit including a direct current (DC)/DC converter, which converts the level of DC power to supply same to a load; and a control unit for controlling the operating frequency of the DC/DC converter, wherein the control unit can change the resonance frequency of the DC/DC converter according to the load.