Dual-Boost PFC Converter Single Current Sensor Control
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Solution Overview
Problem
Standard boost PFC converters are not suitable for dual-boost PFC converters due to the complexity of precise current sensing caused by the split load current into multiple circuit branches, which requires additional current sensors and increased circuit complexity.
Innovation Solution
A dual-boost PFC converter circuit with an active rectifier stage and two boost stages, utilizing an active rectifier controller and a PFC controller to generate control signals for the rectifier and boost transistors, allowing a single current sensor to sense the current through the active rectifier stage and generate PWM control signals for efficient operation, thereby simplifying the control circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a dual-boost PFC converter topology is used to reduce conduction losses and cooling requirements, then energy efficiency is improved, but current sensing precision deteriorates due to split load current into multiple circuit branches
Solution Approach 1:
The patent introduces an intermediary current sensing resistor placed in series with the active rectifier stage that measures the total input current before it splits into multiple branches. This intermediary measurement point allows accurate current sensing without requiring direct measurement in each split branch, resolving the contradiction between using dual-boost topology for energy efficiency and maintaining current sensing precision.
2Object-generated harmful factors
If a dual-boost PFC converter topology is used to minimize reactive power on the grid, then power factor is improved, but control circuit complexity increases due to need for multiple current sensors
Solution Approach 1:
The patent makes the single current sensing circuit serve multiple functions: it senses the total input current for power factor correction control, provides feedback for active rectifier switching synchronization, and enables PWM generation for both boost stages. This multi-functionality eliminates the need for separate current sensors in each branch, resolving the contradiction between achieving good power factor and maintaining simple control circuitry.
Solution Approach 2:
The patent combines the control functions for active rectification and boost stage switching into a unified control scheme that uses a single current sense signal. The control circuit integrates the rectifier controller and PFC controller functions, merging multiple control loops into a coordinated system that operates with minimal sensing requirements, thus reducing control circuit complexity while maintaining effective reactive power compensation.
3Device complexity
If standard boost PFC converter control is used, then control circuit complexity is reduced, but adaptability to dual-boost topology is lost
Solution Approach 1:
The patent implements a dynamic control scheme where the controller adapts its operation based on the dual-boost topology configuration. The control circuit dynamically switches between different control modes for the active rectifier and boost stages, and dynamically adjusts switching signals based on real-time current and voltage conditions. This dynamic adaptability allows the simplified control circuit to effectively manage the dual-boost topology without requiring dedicated complex control hardware.
Data Source
AI summary
A circuit for use in a switched mode power supply includes a dual-boost power-factor correction converter having an active rectifier stage with first and second rectifier transistors and first and second boost stages each with an inductor and transistor. An active rectifier controller circuit generates control signals for driving the rectifier transistors, respectively, on and off in accordance with an AC input voltage. A PFC controller circuit generates a pulse-width-modulated (PWM) control signal that is based on an output voltage of the boost stages and which is further based on a current sense signal representing the current passing through the active rectifier stage. A logic circuit generates a control signal for the transistor of the first boost stage and a control signal for the transistor of the second boost stage, based on the PWM control signal and at least one of the control signals for the rectifier transistors.