Design and control of a novel module integrated converter with power pulsation decoupling for photovoltaic system

It is popular that several photovoltaic modules connected in series used the same centralized inverter to transfer the energy to the grid. Nowadays, module integrated converters (MIC) are preferred because they can improve the efficiency of PV module even when some of the modules of the total surface are covered and do not receive the same solar irradiation. But MIC needs big capacitor to reduce the power pulsation on the input DC bus. A novel MIC for small photovoltaic (PV) system is proposed to reduce the power ripple with small capacitor. The power decoupling is executed by buck-boost converter with small capacitor. The flyback inverter realizes stable ac current injection into the grid. Meanwhile, a modified perturbation and observation method is presented. The novel MPPT method can adjust the perturb step according to the work point of PV module and has good steady and dynamic characteristic. The effectiveness of the proposed inverter and MPPT control method is verified thorough experiments on a prototype.