Totem-Pole PFC Current Reconstruction Without Direct Sensors
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Solution Overview
Problem
Existing power factor correction (PFC) circuits, particularly totem-pole PFC circuits, face challenges in accurately measuring the PFC input current, leading to inefficiencies and increased costs due to the need for expensive sensors or current transformers, and compromise power factor (PF) and total harmonic distortion (THD) performance when operating in different conduction modes.
Innovation Solution
A totem-pole bridgeless PFC boost converter system that reconstructs the PFC input current using integrated circuitry to measure PFC output current, AC input voltage, and output voltage, eliminating the need for expensive sensors and improving PF and THD performance across various operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive sensors or current transformers are used to measure PFC input current, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses an auxiliary winding on the PFC inductor to create a copy of the magnetic flux information, which is then processed through a controller to reconstruct the PFC input current waveform. This copying approach avoids direct current sensing while capturing the necessary current information through magnetic coupling.
Solution Approach 2:
The patent replaces direct electrical current measurement (which would require physical current sensors or transformers in the current path) with a magnetic field-based measurement using an auxiliary winding. This substitution eliminates the need for intrusive current sensing components while achieving the same measurement objective.
2Loss of energy
If totem-pole PFC circuit topology is used to reduce energy loss, then power efficiency is improved, but difficulty of detecting and measuring PFC input current increases
Solution Approach 1:
The patent introduces an auxiliary winding as an intermediary element that couples the PFC inductor's magnetic field to the control circuit. This intermediary provides a safe and easy interface for measuring current information without requiring direct access to the high-current PFC input terminals, thus simplifying the measurement process in totem-pole topology.
3Ease of operation
If t on control technique is used for DCM QR operation, then ease of operation is improved, but power factor and THD performance deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the controller uses the reconstructed PFC input current information (from the auxiliary winding measurement) to dynamically adjust switching control signals. This feedback loop enables the system to maintain optimal power factor and THD performance across different operating modes while preserving the simplicity of control implementation.
Data Source
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AI summary
A power factor correction (PFC) boost converter system and method of operation includes a control system connected to a bridgeless PFC converter which includes a first voltage measurement circuit connected to measure a first voltage, a second voltage measurement circuit connected to measure a second voltage, and a third voltage measurement circuit connected to measure a third voltage, where the control system is connected to compute a reconstructed PFC input current signal from the first, second, and third voltages and to output a set of control signals for controlling the PFC converter based on the reconstructed PFC input current signal and the boosted output voltage.