Digital implementation of one-cycle controller (OCC) for AC-DC converters

In this paper, a novel method for the digital implementation of one-cycle controller (OCC) is introduced for the control of AC-DC full-bridge converter. The use of this technique eliminates the need of high sampling rates for data acquisition or of using averaged input parameters for control, which is usually the case for digital implementation of OCC. Since, the instantaneous result of integration of switched variable is compared with the reference signal, sampling rates much higher than the switching frequency are required. In the proposed implementation technique, the current ripple is mathematically estimated based on the measured values of input current and voltages sampled at the beginning of each switching cycle. Since the choice of carrier affects the performance of the converter, a generalized triangular carrier is used in the analysis of converter operation using this technique. It allows us to choose an appropriate carrier suitable for this application. This leads to obtaining accurate duty cycles by switching action, while sampling rates remain the same as the switching frequency. The above technique is then used to perform reactive power control on a lab prototype of a boost based AC-DC converter. The simulation and experimental results show satisfactory performance of the converter with the proposed implementation technique.