Power Controller Suppresses Output Voltage Rise in LLC Resonant Display Power Supply
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display apparatuses face an increase in output voltage at high frequencies and low loads, which can lead to inefficiencies and power consumption issues, especially when operating in DPC mode.
Innovation Solution
A power controller adjusts the switching operation of a switching unit or PFC output voltage based on load information to suppress output voltage gains, intermittently controlling switching when the output feedback voltage exceeds certain thresholds, and generating a switch control signal with pulse skip periods in DPC mode to manage power effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the operating frequency of the LLC resonance circuit is increased to reduce the size of the LLC resonance circuit and miniaturize the converter, then the size of the power board is reduced, but the parasitic capacitance of the transformer and secondary rectifier circuit causes the output voltage to rise under light load
Solution Approach 1:
The power controller implements periodic action by intermittently controlling the switching of the switching unit when operating frequency is high and load is light. This involves periodically turning on and off the switching unit based on feedback voltage comparison with thresholds, which suppresses the abnormal output voltage rise caused by parasitic capacitance while maintaining the benefits of high-frequency operation for circuit miniaturization
Solution Approach 2:
The power controller changes operating parameters dynamically by adjusting the switching operation of the switching unit or PFC output voltage based on load conditions. When load is light and frequency is high, the controller modifies the PFC output voltage to suppress gain increase, effectively controlling output voltage without changing the high operating frequency that enables circuit miniaturization
2Loss of energy
If the operating frequency of the LLC resonance circuit is increased to achieve high-efficiency power density and ZVS operation, then power conversion efficiency is improved, but the parasitic capacitance effects become more significant causing output voltage instability
Solution Approach 1:
The power controller uses feedback control by comparing the output feedback voltage with predetermined thresholds (first and second burst thresholds) to determine when to intermittently control the switching unit. This feedback mechanism maintains output voltage stability during high-frequency operation by dynamically adjusting switching based on actual output conditions, preventing voltage rise while preserving the high efficiency benefits of ZVS operation
Solution Approach 2:
The system implements dynamic control by adapting the switching unit operation based on real-time load conditions and feedback voltage. The power controller dynamically switches between different operating modes (continuous switching vs. intermittent control) depending on load level and frequency, maintaining both high efficiency and voltage stability across varying operating conditions
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 approach effectively suppresses abnormal output voltage rises at high frequencies and low loads, enabling efficient power consumption reduction while maintaining stable operation.
Implementation Method 1
an LLC topology capable of ZVS (Zero Voltage Switching) operation is used to realize high-efficiency power density. That is, the display apparatus may supply power using a DC-DC converter including an LLC resonance circuit
Implementation Method 2
An inductor L included in the LLC resonance circuit is characterized in that its size may be reduced when an operating frequency is increased
Implementation Method 3
when the operating frequency is high, the parasitic capacitance of a transformer and a secondary rectifier circuit affects the operation of the LLC resonance circuit, so that an output voltage rises under a light load
Data Source
AI summary
An embodiment of the disclosure provides a display apparatus operating at high frequency, the display apparatus comprising: a display module; a control board that obtains load information; and a power board that supplies an output voltage to the display module and the control board considering the load information, the power board comprising a power factor correction (PFC) circuit, a switching unit, an LLC resonant circuit, a transformer, and a power controller, wherein, when a load according to the load information is less than a light load reference value, the power controller adjusts the switching operation of the switching unit or a PFC output voltage of the PFC circuit to suppress the increase in gain for the output voltage.