Dual-Output Switching Power Supply With Independent PFC Control
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Solution Overview
Problem
Traditional television power supply architectures face inefficiencies in power conversion, high costs, and stability issues due to the need for power factor correction and dynamic load management, especially when dealing with constant-voltage and constant-current outputs.
Innovation Solution
A switching power supply design that incorporates a constant-current switch circuit, single-stage PFC circuit, and transformers to directly convert AC-DC, eliminating high-voltage electrolytic capacitors and allowing separate control of constant-voltage and constant-current outputs, reducing interference and improving stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional power factor correction and DC-DC conversion architecture is used, then power factor can be corrected, but power conversion efficiency is low and system cost increases
Solution Approach 1:
The patent combines the power factor correction function and constant-current control function into a single integrated circuit structure. The PFC circuit shares components with the constant-current output stage, eliminating the need for separate DC-DC conversion stages and high-voltage electrolytic capacitors, thereby improving power conversion efficiency while reducing system complexity
Solution Approach 2:
The PFC circuit is designed to perform multiple functions simultaneously: power factor correction, constant-current regulation for LED backlight, and voltage boosting for mainboard power supply. This multi-functional design eliminates the need for separate dedicated circuits, reducing overall system complexity and component count
2Adaptability or versatility
If constant-voltage and constant-current outputs are alternately output, then both output types are provided, but interference occurs under dynamic load conditions
Solution Approach 1:
The patent separates the constant-voltage output path and constant-current output path into independent control loops. The constant-current control circuit and constant-voltage control circuit operate independently with separate feedback mechanisms, allowing both output types to be provided simultaneously without mutual interference under dynamic load 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 design enhances power factor, reduces system costs, and improves the stability of constant-voltage and constant-current outputs, addressing inefficiencies and cost concerns while maintaining reliability under dynamic loads.
Implementation Method 1
a transformer T1, a constant-voltage control circuit U2, a power management circuit U1 and a constant-current control circuit U3; an output end of the rectifier circuit is connected with a power detection terminal of the power management circuit U1 and a power input end of the transformer T1; a controlled terminal of the transformer T1 is connected with a control terminal of the power management circuit U1
Data Source
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AI summary
The present disclosure discloses a switching power supply and a television. The switching power supply includes a constant-current switch circuit, a first single stage PFC circuit, a first transformer, a constant-current feedback circuit, a constant-voltage switch circuit, a second single stage PFC circuit and a second transformer; the constant-current feedback circuit samples a current outputted by the first transformer, and feeds back the sampled current to the first single stage PFC circuit; the first single stage PFC circuit outputs a switch signal, and drive the constant-current switch circuit to be turned on or off, so as to control a load current to be constant according to the sampled current; the second single stage PFC circuit outputs a switch signal and drive the constant-current switch circuit to be turned on or off; the second single stage PFC circuit samples a voltage outputted by the second transformer to obtain a sampled voltage, and regulates the duty ratio of the switch signal according to the sampled voltage, to regulate the voltage output to a main board, so that to control the voltage of the load to be constant. The solution of the present disclosure improves the power conversion efficiency and stability, and reduces the cost.