Output-Referenced Energy Reservoir Power Factor Correction
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Solution Overview
Problem
Conventional ac-dc power supplies for LED loads face challenges in achieving high power factor, efficiency, and galvanic isolation while maintaining a regulated output, often requiring multiple stages and increasing complexity and cost.
Innovation Solution
A single-stage ac-dc power supply with power factor correction and an output-referenced energy reservoir, utilizing a flyback converter and a regulator circuit to store and deliver energy at a constant rate, ensuring a high power factor and regulated output while minimizing energy storage at high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a storage capacitor is used at the input to store energy, then energy storage capability is improved, but rms input current and line frequency harmonics increase
Solution Approach 1:
Instead of placing the storage capacitor at the input side (conventional approach), the patent places it at the output side of the power conversion stage. This inversion allows the capacitor to be charged by the switching regulator in controlled pulses rather than directly from the AC line, eliminating the harmful current draw and harmonics while maintaining energy storage capability.
2Reliability
If multiple stages of power conversion are used to achieve high power factor and galvanic isolation, then power factor and isolation are improved, but device complexity increases
Solution Approach 1:
The patent combines power factor correction, galvanic isolation, and output regulation into a single integrated power conversion stage using a switching regulator with pulse-by-pulse control. This merging eliminates the need for separate power factor correction circuits and multiple conversion stages, reducing overall system complexity while maintaining all required functions.
Solution Approach 2:
The switching regulator is designed to perform multiple functions simultaneously: it provides galvanic isolation through its transformer, achieves power factor correction through controlled rectification, regulates the output voltage, and charges the output capacitor. This multi-functionality in a single stage reduces the overall number of components and simplifies the system architecture.
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 configuration allows for efficient energy delivery, reduced volume, and higher packaging density, achieving a high power factor and regulated output with lower energy storage requirements, thus addressing the challenges of cost and complexity in conventional designs.
Implementation Method 1
The power supply includes a reservoir output that stores energy... a reservoir capacitor (CRES) that receives a reservoir voltage (VRES) from the second output winding (422) of the transformer
Implementation Method 2
A flyback converter... utilizing a flyback converter and a regulator circuit to store and deliver energy... The power supply includes a transformer (418) that provides galvanic isolation between the input and the output
Data Source
AI summary
An ac-dc power supply includes a dc-dc converter coupled to an input of the ac-dc power supply. The input of the ac-dc power supply is coupled to receive an ac input voltage and an ac input current. The dc-dc converter includes a regulated output and a reservoir output. A controller is coupled to receive sense signals from the dc-dc converter. The controller is coupled to control the dc-dc converter to regulate the regulated output in response to the sense signals. The controller is further coupled to control a waveform of the ac input current to have a substantially same shape as a waveform of the ac input voltage. A regulator circuit is coupled to the regulated output and the reservoir output. The controller is coupled to the regulator circuit to control a transfer of energy from the reservoir output to the regulated output through the regulator circuit.