Power Factor Controller Phase Shifted Multiplier
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Solution Overview
Problem
Existing power factor correction methods for LED drivers are limited in scope and application, particularly at high line voltages and light loading conditions, where input capacitors cause poor power factor due to leading current issues, and current regulation techniques do not effectively translate to all power factor correction topologies like boundary conduction mode boost or discontinuous mode Flyback converters.
Innovation Solution
A power factor controller system comprising a boost converter, a programmable controller for estimating a phase-shifted and blanked multiplier, and a current regulator to generate a desired power factor correction current, which can be applied to a broader class of control methods, including sinusoidal input current generation and operation of an LED driver based on the desired input current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If input capacitors are placed before and after the rectifier to control EMI, then EMI is reduced, but power factor deteriorates due to leading current at high line voltages and light loading conditions
Solution Approach 1:
The patent implements a feedback control mechanism where the controller monitors the input voltage and load conditions, then dynamically adjusts the PFC current waveform to compensate for the leading current caused by input capacitors. This closed-loop control ensures power factor remains within specified limits across varying operating conditions while maintaining EMI filtering capability.
Solution Approach 2:
The patent changes the control parameters of the PFC converter based on operating conditions. At high line voltages and light loading, the controller modifies the reference current waveform parameters to counteract the capacitive leading current effect, thereby maintaining acceptable power factor without removing the EMI filtering capacitors.
2Reliability
If known power factor correction methods are applied to LED drivers, then power factor is improved under certain conditions, but the methods are limited in scope and do not translate to other topologies like boundary conduction mode boost or discontinuous mode Flyback converters
Solution Approach 1:
The patent develops a universal PFC control method that can be applied to multiple converter topologies including continuous mode boost, boundary conduction mode boost, and discontinuous mode Flyback converters. The controller implements a generalized approach to PFC current generation that adapts to different topology characteristics while achieving consistent power factor correction performance across all supported topologies.
Data Source
AI summary
A power factor controller (PFC) for an electrical load such as LED lighting includes a power factor correcting converter for generating a sinusoidal input current. The PFC further includes a programmable controller for estimating a phase shifted multiplier. A current regulator generates a desired PFC current in response to an input voltage, an output load and the phase shifted and subsequently blanked multiplier. The electrical load operates in response to the sinusoidal input current based at least partially on the desired PFC current.