A unified analysis and design procedure for a standardized control module for dc-dc switching regulators

Abstract

Three basic switching regulators: buck, boost, and buck/boost, employing a multi-loop control module (SCM) were characterized by a common small signal block diagram. Employing the unified model, regulator performances such as stability, audiosusceptibility, output impedance and step load transient are analyzed and key performance indexes are expressed in simple analytical forms. More importantly, the performance characteristics of all three regulators are shown to enjoy common properties due to the unique SCM control scheme which nullifies the positive zero and provides adaptive compensation to the moving poles of the boost and buck/boost converters. This allows a simple unified design procedure to be devised for selecting the key SCM control parameters for an arbitrarily given power stage configuration and parameter values, such that all regulator perfor mance specifications can be met and optimized concurrently in a single design attempt.

Input filter interactions in peak-current-mode-controlled buck converter operating in CICM

“…), when the converter operates in the second harmonic mode. These telltale signs validate the proposed modeling approach with the excellent dynamical predictions demonstrated earlier in [17]- [20].…”

“…It has turned out [21] that the modeling, resulting in an infinite duty-ratio gain at the mode limit between the basic switching-frequency operation and the second harmonic mode, describes the converter dynamics both in a small-signal and large-signal sense extremely well. Similar results based on different approaches [17]- [20] have been proposed earlier, but they have been disputed as in [24] due to the lack of profound evidence, even if this evidence has always been at hand [21]. Similar behavior has been reported to take place, also, when a converter operates in discontinuous mode [22].…”

“…That is why we have not encountered any difficulties, even if the converter is operated close to the normal mode limit of 50%. (20) Similar duty-ratio constraints as shown in Table I have also been presented earlier based on many different approaches [17]- [20], but the validity of them has been disputed in several research reports, such as in [24]. The main criteria of disputing have been based on the lack of evidence from the infinite duty-ratio gain.…”

“…This gives (17), where the transfer matrices and are defined in (18), respectively. The elements of the matrices are the input admittance , the output current susceptibility , the audio susceptibility , the output impedance , the control-to-inputcurrent transfer function and the control-to-output-voltage transfer function (17) …”

A unified model for current-programmed converters

“…The unified modulator model of (6) is a modification of that proposed in [5], and the modulator gain factor F, is equivalent to that of [12]. In terms of Fm and k , (6) becomes…”