PFC Circuit Operation Time Control for Display Power Supply
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Solution Overview
Problem
Existing power supply devices for display apparatuses are inefficient in standby mode due to the lower efficiency of the LLC resonant circuit when generating driving voltage without burst voltage, as the switching operation in the PFC circuit is stopped, leading to increased power consumption.
Innovation Solution
A power supply device that controls the operation time of the power factor compensation (PFC) circuit based on the size of the output load, using a sensor to determine the load size and an LLC resonant converter to selectively operate the PFC circuit in a burst mode, providing Vcc voltage only for proportional operation times to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the PFC circuit switching operation is stopped in standby mode, then power consumption is reduced, but the LLC resonant circuit efficiency decreases due to receiving low voltage instead of burst voltage
Solution Approach 1:
The PFC circuit is operated periodically in burst mode during standby state instead of continuously or completely stopped. The controller activates the PFC circuit for specific burst periods to generate high voltage, then stops it, creating periodic action that balances power consumption and conversion efficiency
Solution Approach 2:
The operating state of the PFC circuit is dynamically adjusted between standby state and burst mode based on real-time detection of output load size. When load exceeds threshold, PFC operates in burst mode; otherwise it operates periodically, making the system adaptive to different operating conditions
2Loss of energy
If the PFC circuit operates continuously in burst mode, then conversion efficiency is improved, but power consumption increases in standby mode
Solution Approach 1:
The PFC circuit operates in periodic bursts rather than continuously during standby mode. The controller enables the PFC circuit for specific time intervals to maintain conversion efficiency while allowing sufficient off-time to reduce overall power consumption
Solution Approach 2:
The operating parameters of the PFC circuit are changed based on output load conditions. When load is small, the duty cycle and operation time are reduced; when load exceeds threshold, full burst mode is activated, optimizing the balance between efficiency and power consumption
3Reliability
If the PFC circuit operation time is increased, then power factor compensation performance is improved, but power consumption increases
Solution Approach 1:
The PFC circuit operates periodically with controlled duty cycle during standby state, providing sufficient power factor compensation for light loads while limiting operation time to reduce power consumption
Solution Approach 2:
The operation time and duty cycle of the PFC circuit are dynamically adjusted based on detected output load size, optimizing the balance between power factor compensation performance and power consumption for different 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 solution enables the power supply device to operate efficiently even in standby mode by controlling the PFC circuit's operation time, reducing power consumption and improving conversion efficiency in the converter, thereby decreasing standby power.
Implementation Method 1
a rectifier configured to rectify external AC power to DC power
Implementation Method 2
a PFC circuit configured to selectively operate in a burst mode using the rectified DC power
Implementation Method 3
a converter comprising circuitry configured to transform an output voltage of the PFC circuit into the driving power
Implementation Method 4
LLC resonant converter configured to operate using a plurality of switches
Data Source
AI summary
A display apparatus is provided. The display apparatus includes a display configured to display an image, an image signal provider circuit configured to provide an image signal to the display, and a power supply configured to generate driving power and to supply the generated driving power to the image signal provider, wherein the power supply controls an operation time of a power factor compensation (PFC) circuit which performs power factor compensation of the display apparatus based on a size of an output load receiving the driving voltage.