Open AccessDirect digital design of a sliding mode‐based control of a PWM synchronous buck converter
Author(s) -
VidalIdiarte Enric,
MarcosPastor Adria,
Giral Roberto,
Calvente Javier,
MartinezSalamero Luis
Publication year - 2017
Publication title -
iet power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.637
H-Index - 77
eISSN - 1755-4543
pISSN - 1755-4535
DOI - 10.1049/iet-pel.2016.0975
Subject(s) - control theory (sociology) , pulse width modulation , duty cycle , buck converter , transfer function , inductor , converters , digital control , voltage , controller (irrigation) , sliding mode control , computer science , engineering , physics , electronic engineering , nonlinear system , control (management) , agronomy , artificial intelligence , quantum mechanics , electrical engineering , biology
A discrete‐time sliding mode approach allowing direct digital design of a pulse width modulation (PWM) control of a synchronous buck converter is presented in this study. Without the need of a compensating ramp, a non‐linear difference equation representing the output voltage dynamic behaviour is employed to demonstrate the global stability of the internal control loop of the inductor current. Discrete‐time small‐signal model is derived from the linearisation of the ideal sliding‐mode equations, which facilitates the design of the output voltage controller. This model exhibits a zero whose value depends on the operating point coordinates and explains the duty cycle delay associated to digitally PWM controlled converters. The validity of the transfer function is demonstrated through simulation by comparing its frequency behaviour with that obtained from the more accurate switched model of the converter. Experimental results for start‐up, load and line perturbations, current and voltage reference variations in a 25 W prototype switching at 100 kHz are in good agreement with the theoretical predictions.