Current-Limiting Non-linear Controller for Single-phase AC/DC PWM Power Converters

In this work, a non-linear controller with an inherent current-limiting property is proposed to achieve dc output voltage regulation and unity power factor operation for single-phase ac/dc converters. The proposed current-limiting non-linear controller (CLNC) acts independently from the system parameters and is proven to guarantee closed-loop system stability using non-linear control theory. Without requiring the instantaneous measurement of the grid voltage, a PLL or external limiters, the CLNC additionally guarantees that the input current will always remain below a given maximum value, even during transients. This represents a significant superiority with respect to the existing techniques, since a given limit for the input current is achieved without changing the controller dynamics or using external protection circuits. Extended simulation results using both Matlab/Simulink and a real-time digital simulator are presented to verify the proposed controller performance under several changes of the reference voltage.