Development of a new control strategy for variable frequency operation of boost inverter

Abstract

This thesis proposes, analyzes and verifies a control scheme to regulate the output voltage of the boost inverter. The proposed control scheme maintains sinusoidal output voltage for variable frequency and constant input/output voltages. At first a conventional boost inverter is designed and investigated for variable frequency operations. The output of conventional inverter remains sinusoidal at certain frequency but when the frequency of the controller is changed the voltage across the load becomes nonsinusoidal. To alleviate this problem, modification of Boost converter topology is proposed and a new control circuit to generate PWM switching signals is designed. Accordingly in this thesis Boost converter topology of the two Boost circuits used in DC-AC Boost inverter is modified. In addition, a new open loop control circuit is proposed and implemented to have inverter output voltage near sinusoidal. The input/output voltage variations for variable load have been maintained to desired levels by adopting proper control in the proposed control circuit. The modulator for this control circuit is designed such that with frequency control, the amplitude of the modulating signal is adjusted according to formula derived from simulation data so that output remains sinusoidal.