Digital current balancing for an interleaved boost PFC

Focus:

In a two-phase interleaved PFC boost converter, different methods are available for balancing or equalizing the currents between the two phases. This article describes three digital-control methods for current balancing, but focuses primarily on an approach that makes use of the company’s second-generation digital controller, the UCC3138, which implements two current loops that independently control the current in each phase. Prior to describing this “dual current-control loops” method in detail, the article describes two other digital control methods—one that adjusts the duty cycle of a single phase on a cycle-by-cycle basis and another that adjusts the duty cycle once per half ac cycle—and points out their limitations (high-frequency noise and distortion). With that as background, the principles of operation and advantages of the dual current-control loops method are explained. Simplified schematics and test results for all three control methods are shown.

What you’ll learn:

• How to use digital control methods to balance currents between phases in a two-phase interleaved PFC boost converter
• How to perform current balancing in a two-phase interleaved PFC boost converter using two digitally controlled current loops
• How to manage current sharing in a two-phase interleaved PFC boost converter

Notes:

This article appeared in Texas Instruments’ Analog Applications Journal, 2Q 2013. Based on that, the publication date is approximated here as April 1, 2013.

View the Source

Author & Publication:

Bosheng Sun, Systems Engineer, Texas Instruments, Vendor website, Apr 01 2013

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