Research on Multilevel Inverter Based on Switched-capacitor Cell
In order to approach a voltage of high magnitude in photovoltaic(PV)application,several PV modules are connected in series to form a PV string,the voltage of PV string is converted to an AC voltage through an H-bridge inverter.This system causes harmful harmonics,brings about leakage current,and increases the voltage stress of the components.In view of the above problems,a new multilevel inverter topology is proposed based on switched-capacitor cell that uses series-connected DC sources as the input DC source and generates a staircase AC voltage of high quality and mitigates the leakage current.Moreover,the proposed topology can be easily extended to a three-phase inverter,where the three phases only connect to a single series photovoltaic module or DC power source in the three-phase topology.The operation principle,the level-shifted sinusoidal pulse width modulation(SPWM)strategy,leakage current and circuit parameters of proposed multilevel inverter are analyzed in detail.A comparative analysis is also conducted between the proposed multilevel inverter and existing multilevel inverters.Finally,the simulation model is established by Matlab,and the experimental prototype is made.The effectiveness and feasibility of the proposed circuit are verified by simulation and test results.