Solar Inverter Control

Solar Micro Inverter Control

DC-DC stage has MPPT (maximum power point tracking) followed by a voltage controller. MPPT system sense the panel voltage and panel current and adjust the  current from panel to give maximum power. MPPT gives a voltage reference to the voltage controller. Voltage controller has a PI controller that compare the reference voltage with the panel voltage to generate PWM for flyback switch. Flyback has MOSFET as its switch and voltage controller generates a PWM with 100kHz frequency. 

Figure 1: DC-DC Control

DC-AC stage has two PI controllers followed by a bipolar PWM generator.  First PI controller compare the DC link voltage with 200V and generate a voltage reference. That voltage reference get multiply with the grid voltage to generate a sinusoidal current reference in phase with the grid voltage. This reference get compare with the output current to the grid to generate the reference for PWM. Then, bipolar PWM generates a switching signals for the full bridge.  

Figure 2: DC-AC Control