Ripple Mitigation With Improved Line-Load Transients Response in a Two-Stage DC–DC–AC Converter: Adaptive SMC Approach

Abstract

A substantial pulsation of the second-order harmonic current ripple with angular frequency 2ω is reflected at the input of a single-phase inverter when loads are supplied at its output with angular frequency ω. Moreover, this ripple back-propagates and injects into the source in the absence of a bulky dc-link passive filter, an active compensator or a suitable digital controller with a front-end converter in the two-stage converter. This paper proposes a new adaptive sliding mode control for a two-stage dc-dc-ac converter to reduce proliferation of ripple without compromising dynamic performance. The front-end boost converter in the considered two-stage converter interfaces a battery bank and single-phase inverter fed loads. The control shapes the output impedance of the boost converter to reduce the ripple component at battery input. Second, the proposed controller achieves good dynamic performance at line and load transients. A fast voltage recovery with small undershoot/overshoot can be achieved at transients using the proposed controller. The proposed technique is validated using a hardware of the 1-kW two-stage converter.