Predictive Energy Balancing Enhances Control of Power Converters

by Tom Lawson, CogniPower, Malvern, Penn, How2Power Today, Jan 27 2012

Focus:
Conventional pulse width modulation (PWM) control for switched-mode power supplies (SMPSs) must compromise two conflicting goals; stability versus agility. Various schemes for improving the outcome of the stability/agility compromise fill the literature, but do not dispatch the issue. However, a novel control technique known as Predictive Energy Balancing sidesteps the PWM control problem entirely. Through energy prediction, the phase lag of the output filter is removed from the feedback path. The underlying principle is that the voltage on the filter capacitor after the inductive energy from the switched inductor has been transferred can be calculated in advance. Given that information, the decision to switch from energizing the inductor to transferring inductive energy to the output can be made on the basis of the energy outcome at the end of the control cycle. That simple concept removes constraints that have long limited the performance of power converters. In this article, the underlying math and practical techniques for implementing Predictive Energy Balancing are explained, and experimental results for a flyback converter using this technique are presented. Article concludes by oting the applicability of Predictive Energy Balancing to other power supply topologies.

What you’ll learn:

• How to understand operating principles behind Predictive Energy Balancing and its potential uses and benefits
• How to improve converter transient response through use of the Predictive Energy Balancing

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