Nonlinear control of single-phase PWM rectifiers with inherent current-limiting capability

In this paper, a nonlinear controller with a currentlimiting property is proposed to guarantee accurate dc output voltage regulation and unity power factor operation for singlephase PWM rectifiers without the need of a phase-locked-loop (PLL). The proposed current-limiting controller is fully independent of the system parameters and can guarantee asymptotic stability and convergence to a unique solution for the closedloop system using nonlinear control theory. Without requiring the instantaneous measurement of the grid voltage, a PLL, an external limiter or a saturation unit, the proposed strategy guarantees that the input current of the rectifier will always remain below a given value. An analytic framework for selecting the controller parameters is also presented to provide a complete controller design procedure and it is also proven that the currentlimiting property is maintained even when the grid voltage drops. Extensive experimental results are presented to verify the proposed controller when the load changes, the reference dc output voltage changes and the grid voltage drops.