Display Power Supply PFC Switching for AC/DC Input Detection
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Solution Overview
Problem
Display devices with power factor correction (PFC) circuits face inefficiencies due to the need to maintain a power factor of 0.9 or more, leading to increased power conversion time and decreased system efficiency, especially when DC power is applied, as the PFC circuit is required even when not necessary.
Innovation Solution
A display device and method that includes a PFC controller to selectively turn the PFC circuit on or off based on the type of input power, using a diode bridge for rectification and NTC sensors to identify AC, DC, or AC/DC power, thereby optimizing the operation of the PFC circuit and reducing unnecessary power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PFC circuit is always on to satisfy power factor regulations, then the power factor requirement is met, but power consumption increases and system efficiency decreases
Solution Approach 1:
The PFC circuit's operational state is dynamically adjusted based on real-time detection of input power type. The controller monitors the input power characteristics and switches the PFC circuit between on and off states, transforming it from a static always-on configuration to a dynamic conditional operation mode, thereby reducing unnecessary power consumption while maintaining compliance when needed
Solution Approach 2:
The system changes the operational parameter of the PFC circuit from a fixed state to a variable state based on input power characteristics. By detecting whether the input is AC or DC power and adjusting the PFC circuit's operational state accordingly, the system optimizes power factor compliance while minimizing energy waste
2Reliability
If the PFC circuit is always on, then power factor regulations are satisfied, but the power conversion process becomes longer
Solution Approach 1:
The PFC circuit operates dynamically based on detected input power type. When AC power is detected, the PFC circuit is activated to ensure proper power factor compliance; when DC power is detected, the PFC circuit is deactivated, shortening the power conversion process and reducing unnecessary processing time
3Reliability
If the PFC circuit is always on, then power factor regulations are satisfied, but system efficiency decreases
Solution Approach 1:
The system implements dynamic control of the PFC circuit based on real-time detection of input power type. The controller activates the PFC circuit only when AC power is detected and deactivates it when DC power is detected, optimizing system efficiency by eliminating unnecessary PFC operations while maintaining power factor compliance when required
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 power consumption and enhances system efficiency by only activating the PFC circuit when necessary, improving the overall power conversion process and reducing standby power loss.
Implementation Method 1
a diode bridge configured to rectify input power
Implementation Method 2
at least two negative temperature coefficient of resistance (NTC) sensors provided between the diode bridge and the PFC controller
Data Source
AI summary
A display device includes a diode bridge configured to rectify input power; a power factor correction (PFC) circuit configured to control a power factor of the input power rectified by the diode bridge; a direct current (DC)/DC converter configured to change voltage of the input power received through the PFC circuit; and a PFC controller connected to the diode bridge and configured to selectively turn on or off the PFC circuit based on terminal voltages of lower diodes included in the diode bridge.