The DC input from the PV module is fed to the buck inverter stage. A modulated high-frequency sine PWM issued for the buck MOSFET to generate the rectified sine output voltage/current across the buck output.
A modulated sine PWM generates modulated sine MOSFET current. The average of the sine modulated secondary diode current produces a rectified sine voltage/current across the output capacitor. An SCR full-bridge is used to unfold rectified output voltage/current to sinusoidal voltage/current. Therefore, the SCR is switched at line frequency.
The output of the inverter is synchronized with the grid by digital PLL. The MPPT controls the magnitude/ rms of the output current. The shape of the output current is controlled by current control loop. Sine modulated PWM operation of the buck MOSFETs transfers the packet of energy to the inverter output capacitor.