Decreasing quantization effects in a buck converter controlled by GZAD strategy

Abstract

ZAD strategy has been widely analyzed in the last decade to control buck power converters. The first models were ideals; as consequence of these numerical and experimental results did not agree. The discrepancy between both of the results is probably due to the sensitivity of the ZAD strategy to compute the duty cycle. In the present work the inductor internal resistance and the quantization effects are included in the converter model. The effect of the inductor internal resistance is to move the stability limit to the left while the qualitative behavior is preserved. The quantization has a high incidence in the dynamics. In this paper we present a strategy to decrease the quantization effects in a buck converter controlled by Digital-PWM based on Zero Average Dynamics on Error (ZAD). The quantization errors are introduced by analog-to-digital converters and Digital-PWM, producing undesirable behavior. We present a methodology to decrease these errors, first using Generalized ZAD and after, computing the duty cycle as the mean of the actual and previous duty cycles. These actions diminish drastically the error and limit cycling oscillations.