Additional Arm for Voltage Boost Operation in Three Phase Voltage Source Inverter

There is a decrease in voltage output of traditional Voltage Source Inverter (VSI) as compared to that of the input DC voltage. A small decline in the input DC supply of a VSI causes the three phase voltage output to reduce drastically and thus cause interruption of crucial load. Another problem with the traditional VSI is that there is a risk of false gating i.e., the two switches in the half bridge of the inverter being closed simultaneously when the dead time in the gate pulses is implemented inaccurately. These issues are tackled using the Quasi-Z-Source Inverter (QZSI) possessing voltage boost capability. But the boost operation in the QZSI is dependent on shoot-through states created using main triangular carrier signal of the Sine Pulse Width Modulation (SPWM) and thus on the modulation index of the SPWM. The dependency of the QZSI operation on the main SPWM causes interference with the main SPWM and the boost operation of the QZSI cannot be controlled independently. Thus in order to create the shoot through states for the QZSI without interfering with the main SPWM an additional switch is introduced parallel to the inverter half bridges which will be used to create shoot through states for the boost operation of QZSI independent from the main SPWM. The modifications carried out in the QZSI are analysed with MATLAB SIMULINK software.