Comparative Evaluation of Three-phase Voltage and Current Source Inverter in Renewable Energy System

摘要

In the renewable energy power generation system, voltage source inverters (VSIs) are commonly used due to its stable operation, high efficiency and low cost. However, a dc-dc boost converter is necessary for VSI to operate has increased the system complexity. Thus, current source inverters (CSIs) has become an alternative of VSI due to its ability of voltage boosting and can provide a better output waveform. This paper presents a comparative evaluation of VSI and CSI focusing on topological circuits and basic operational parameters of these inverters. The performances of VSI and CSI are analyzed in MATLAB/Simulink focusing on two operational characteristics which are modulation index, m_(a) and switching frequency, f_(sw). The performance of VSI and CSI are dependent on the modulation index, increasing m_(a) increase the inverter efficiency. In term of switching frequency, it does not affect much on the efficiency of inverters, yet a normalized switching frequency of odd multiple of three provides better fundamental output and harmonic minimization. Furthermore, CSI presents its voltage boosting capability which can boost 6-27% within m_(a) of 0.05-1.0 and using the same modulation technique, VSI and CSI have present duality relationship in term of output voltage and current wave shapes.