Auxiliary-Winding PFC Bypass in Low-Power USB PD Chargers
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Solution Overview
Problem
USB PD chargers with output power lower than 75 W consume additional power due to the operation of power factor correction converters, which is inefficient.
Innovation Solution
A power supply system that disables power factor correction when output power is below a threshold by using an auxiliary winding to detect voltage, providing a bypass connection from rectified power to first output power, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power factor correction converter operates continuously, then power factor is corrected and harmonics are minimized, but power consumption increases when output power is low
Solution Approach 1:
The power factor correction converter dynamically changes its operating state based on output power level. When output power exceeds the threshold, the PFC converter operates to correct power factor; when output power is below the threshold, the PFC converter is disabled to reduce power consumption. This dynamic adaptation resolves the contradiction between maintaining power factor correction and reducing energy consumption.
Solution Approach 2:
The system changes the operational parameter (power factor correction function) based on the output power level. By monitoring output power and comparing it to a threshold value, the system adjusts whether PFC is active or inactive, thereby optimizing the balance between power quality and energy efficiency under different operating conditions.
2Use of energy by moving object
If power factor correction converter is disabled to reduce power consumption, then power savings are achieved, but power factor correction and harmonic minimization are lost
Solution Approach 1:
The system dynamically adjusts the operational state of the PFC converter based on output power parameters. When output power is below the threshold, PFC is disabled to save energy; when output power exceeds the threshold, PFC is enabled to maintain power quality. This parameter-based control resolves the contradiction between energy savings and power factor maintenance.
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
Reduces power consumption by stopping power factor correction when output power is below a certain threshold, optimizing energy efficiency.
Implementation Method 1
a transformer, comprising a primary winding, a secondary winding, and an auxiliary winding which are coupled to one another, wherein the auxiliary winding is configured to generate an auxiliary voltage
Data Source
AI summary
A power supply system includes a power factor correction converter circuit and an isolated power converter circuit, wherein the power factor correction converter circuit corrects the power factor of a rectified power to generate a first output power, and the isolated power converter circuit converts the first output power to generate a second output power. The isolated power converter circuit includes a transformer, and the transformer includes a primary winding, a secondary winding, and an auxiliary winding. The auxiliary winding generates an auxiliary voltage which is related to the second output power. When the auxiliary voltage is lower than a disabled threshold, indicating that the voltage of the second output power is lower than a threshold, the power factor correction converter circuit provides a bypassing connection from the rectified power to the first output power and stops correcting the power factor of the rectified power.