Operation and Control of a Grid-Connected Asymmetrical Cascaded Multilevel Inverter

This article presented a new structure for the grid-connected multilevel inverters (MLIs) circuit with the ability of the cascaded connection. The proposed inverter is capable of transformerless connection of distributed generation resources to the network. The control system manages the power injection to the grid by minimizing the output current harmonics as well as exchanging reactive power with the grid. The self-balancing state of the capacitors' voltage is occurred only with the switching technique without any measurement sensors. An enhanced phase-locked loop (EPLL) and a proportional resonant (PR) controller are employed for the proposed asymmetric MLI. An important feature of the proposed inverter is the ability of stable performance and fast dynamics of the control system to the changes of the reference values. Simulation and experimental results are presented in order to validate the performance accuracy of the proposed MLI.