Comparative Study of Microinverters Topologies and Control Schemes for Photovoltaic Applications

Abstrak

Photovoltaic (PV) energy is one of the most promising emerging technologies for renewable energy sources. An alternative solution for photovoltaic (PV) generation systems is the grid-connected AC module. It combines the PV panel with the microinverter connected to the grid. A transformer is a key component of a grid-connected photovoltaic (PV) microinverters system regarding safety and power quality issues. The microinverter shall ensure that the maximum power operation of the PV module is carried out with the Maximum Power Point Tracking (MPP) and Total Harmonic Distortion (THD) should not be more than 5% according to the standards of IEEE 1547 and IEC 6172. With the aid of the MATLAB Simulink software, the comparative study of double stage isolated microinverter topologies for PV systems is presented in this paper. The multistage microinverter consists of six isolated topologies of DC-DC converter with maximum power point tracking (MPPT) and H-bridge inverter. The control algorithms are implemented according to the Perturbation and Observation (P&O) method. The device switching is controlled by using MOSFET with a frequency value of 100kHz for converter switching and 20kHz for inverter switching. The designs made have met the requirements of Vout = 230V (rms), Iout = 0.923A, Pout = 300V and, output frequency = 50Hz. The design of microinverters modelled in this study is Fly-back, Interleaved Fly-back, Push-Pull, Current-Fed, Half Bridge, and Full-Bridge. As a result, by comparing all of the 6 topologies microinverters designed, the Flyback Microinverter was proposed. The THD rates for flyback microinverter is measured at 1.24% in FFT spectrum, and the transformer ratio value of 3.7 compared to other design.