Anotace:
In This paper, a simple single-dimension Space Vector Modulation (SVM) technique is introduced to implement on three-phase thirteen-level Modified Packed U-Cell (MPUC) inverter for photovoltaic system in which many DC sources are available. The three-phase thirteen-level converter consists of three single-phase seven-level MPUCs that each phase has six switches and two isolated DC sources. One major advantage of proposed method is to produce an output voltage with nearly constant amplitude in desired range in case of input DC voltage fluctuations, which is common in renewable sources like Photovoltaic Systems (PV). On the other hand, the conventional Pulse Width Modulation (PWM) strategies do not have such capability. Thus, the converter behavior is investigated for the proposed control method and Level Shift PWM (LS-PWM) and it is shown that the LS-PWM method does not function properly when the DC voltage varies. In order to produce an output voltage with seven equal levels, which results in reduction of the switching losses and Total Harmonic Distortion (THD), it is necessary to trigger switches in proper way. Consequently, two switching patterns are introduced and the significant decrease in power loss due to the second switching pattern is shown. Furthermore, it is investigated that in three-phase mode, the 3rd order line-voltage harmonics are eliminated well and the voltage and current THD are further improved by the proposed method. To validate the proposed SVM technique, MATLAB Simulink simulation results are presented and a comparative analysis is done between the proposed method and LS-PWM.