Optimization of discrete-time controller applied to DC-DC step-down converter

Abstract

The paper describes the optimization of a discrete-time controller designed on the basis of discrete root locus for the boost converter operating at 1000 kHz. The optimization is accomplished through a nonlinear least squares method. The digital control theory is not as rich as the analog control theory. Locating poles and zeros directly in the z-plane by a designer to render the required performance is a difficult task to accomplish. Direct placement of poles and zeros may also introduce distortion as well. Consequently, direct digital design approach based digital controller may not offer satisfactory performance. The poles and zeros are disturbed around their nominal positions through the optimization technique to snub the atrocities introduced by the unwanted digital phenomena. Effect of nonlinearities in the form of ADC/DAC quantization error, delay, etc. on performance is also accentuated. The effectiveness of the application of the optimization technique to the buck converter is investigated using the MATLAB/Simulink environment.