Analysis and Modulation of the Buck-Boost Voltage Source Inverter (BBVSI) for Lower Voltage Stresses

ABSTRACT

Renewable energy sources entail the powerelectronics inverters are the orbit of research objectives foroptimum operation. Two commonly used inverters exist; thecurrent source inverters (CSI) and the voltage source inverters(VSI). The first one supports only the boost capability and theother supports the buck capability, but due to the high variationof the output voltage of these renewable energy sources a buckboostcapability is a must. This buck-boost capability requiresthe enforcement of the aforementioned inverters with anadditional stage for the amendment of the energy source output,which greatly reduces the overall efficiency. Instead of such twostage power conversion operation, a single stage operation couldbe obtained using the Z-source inverter (ZSI). The so-called ZSIexploits an impedance network to achieve such capability. Thisimpedance network comprises four passive elements and asemiconductor switch, which is relatively bulky and costly. Thisproject proposes the analysis and the modulation scheme ofanother inverter topology, called the buck-boost voltage sourceinverter (BBVSI), to get the buck-boost capability in a singlestage power conversion operation with less passive elements andless semiconductor devices ratings. The BBVSI topology exploitsonly two passive elements in addition to a semiconductor switchto give the same function of the ZSI with some merits over it.Moreover, this project compares the BBVSI topology with the ZSItopology. The performance of the BBVSI topology is evaluatedusing MATLAB/Simulink models.

CIRCUIT DIAGRAM

Existing System

In this project, the buck-boost voltage source inverter (BBVSI) topology, is studied, where the analysis and the modulation of this topology is introduced to get the single stage power conversion operation property in addition to less number of passive elements and less semiconductor switches ratings merits. This topology exploits only two passive elements in addition to a semiconductor switch in its impedance network to achieve the property of single stage power conversion operation unlike the other ZSI topologies mentioned before. Furthermore, higher boosting ratio compared to the two stage power conversion operation based on the buck-boost DC-DC converter is obtained as elucidated in the next section.

Proposed System

The BBVSI has the buck and boost capabilities, so it is a promising transformer less inverter topology. The problem with the transformer less topologies is the lack of isolation between the DC side and the AC side. In the simulation results showed before, the BBVSI is fed from a PV array. In any typical PV system, the PV modules are grounded. This results in a capacitance to the ground, which depends on the climate conditions. Due to the high switching frequency, a common mode voltage would exist on the load neutral point, and this could be solved using several methods, which is out of the scope of this project, like common mode chokes, neutral point clamped inverters, and reduced common mode voltage modulation techniques

TOOLS AND SOFTWARE USED:

MP LAB

ORCAD/PSPICE

MATLAB/SIMULINK

OUTPUT:

HARDWARE

SIMULATION