Robust Controllers for a Single-Stage Boost DC-AC Inverter

Abstract

The main feature of a Boost DC-AC inverter is to step-up the input DC voltage and convert this boosted dc voltage into desired AC voltage in a single stage without the use of output filter requirement. The loads fed can be self-governing or solar based home gadgets. The conversion efficiency is less due to more number of stages in a two stage converter. This work aims to simulate a boost DC-AC inverter feeding both linear and non-linear loads in a single stage. Here two boost converters are differentially connected across the load, in order to get a pure sinusoidal waveform as an output. It requires four switches only. Also it is low in cost and in compact size. Two controllers are presented in this work. One is a dual loop controller and other one is a PWM based sliding mode controller. Both the controllers are operated at a switching frequency of 10 kHz. A 220V, 50Hz pure sinusoidal waveform is obtained for different loads (single phase load of 1.5kW, 0.8pf lag) with less steady state error, low THD’ and convergence. Even when a non-linear load is connected both controllers work in a robust manner. It is observed that the PWM based SMC is more accurate in tracking the voltage with less steady state error and settling time. Chattering of SMC is observed through phase portrait. The simulation results are performed using power system computer aided design PSCAD/EMTDC 4.6 tool.