Buck Converter | PartQuest™ Explore

Application Area

Norm
Designer43361

Member for

8 years 7 months

328

designs

2

groups

Buck Converter Reference

Odagiri
Designer206149

Member for

6 years

13

designs

1

groups

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Buck Converter, Structur of PWM Modulator - V7p2

Norm
Designer43361

Member for

8 years 7 months

328

designs

2

groups

Description

V5px, V6px and beyond are working prototypes of my nonlinear SMPS model that that lifts the restriction of averaging from frequency domain SMPS simulations. These initial prototypes are restricted to Voltage Control applications. My intent is to lift that restriction in a subsequent model enhancement.The circuit modeling follows Vorperian's concept [1] of introducing equivalent circuits for the PWM modulator and the switch leaving the remainder of the converter as is. The PWM modulator and switch model nonlinearities by sourcing voltages at frequencies outside the external stimulae. With the restriction of averaging lifted the model becomes applicable at arbitrary frequencies across the spectrum up to and beyond the UHF band where EMI is studied, At frequencies below Fsw the model should produce the same results as the averaged switch.This initial version of the modulator and switch is limited to voltage mode control and continuous conduction. It retains the assumption of small disturbances compared to steady state operation but the derivations make limited use of that assumption.The test bench is the same buck converter Mike Donnelly used to demonstrate TDFS Loop Stability Analysis. I have replaced the switch assembly with an equivalent circuit derived by the methodology Vatche Vorperian documented in his May 1990 paper [1]. I drive the switch with a PWM modulator that sources the Fourier transform of the pulse sequence..The key to coding the models is the use of VHDL-AMS spectral source quantities to formulate Fourier transforms involving products and ratios of waveforms. By this mechanism the models present all the characteristics of the non-linear components in the DC-DC converter. swdrive continues to be derived as a closed form expression of the modulator output but now includes the combined steady state and transient drive signals. The switch model outputs a theoretically correct formulation of the switch outputs, the voltage at the common terminal and the current sourced out of the active terminal.Potential applications:1) Response at high frequencies to arbitrary disturbances including finite pulses, white noise, AM radio, X-Ray radiation...2) Analyze susceptibility to electromagnetic interference (requires modeling of that interference).3) Rad-Hard testing (requires modeling of that interference),4) Generation of RF interference (e.g., by modeling the choke magnetics).This version is under test to determine its accuracy and faithfulness to the actual switching characteristics.[1] See Vorperian's "Simplified Analysis of PWM Converters Using Model of PWM Switch Part 1" in the May 1990 issue (Vol. 26, No. 3) of the IEEE Transactions on Aerospace and Electronic Systems.

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