Research On A Single-stage Boost PV Inverter With Leakage Current Suppression Function

With the rapid development of social economy,fossil fuel and other primary energy are exploited and used in large quantities,which will not only pollute the ecological environment,but also be consumed up eventually due to its limited reserves.Renewable energy such as solar energy,wind energy and biomass energy are attracting more and more attention due to their green and pollution-free advantages.Among them,PV power generation has been paid more attention by governments because of its wide distribution and easy deployment.Due to the low output voltage of a single PV panel,an independent DC boost converter is usually used to raise the voltage of PV cells to a certain value,and then the full bridge inverter is used to generate power or directly provide energy to the AC load.However,the two-stage structure has the disadvantages of more power devices and the efficiency is not easy to improve;at the same time,the traditional bridge inverter has shoot-through problem,which reduces the reliability of the system.In view of the above problems,this paper summarizes the common structure of PV inverter and describes the characteristics of various structures.On this basis,a single-stage boost PV inverter which can suppress leakage current is proposed.There is no shoot-through problem for each bridge arm of the inverter,and there is no need to set the dead-time between the driving signals of each active switch,which is conducive to increasing the switching frequency and improving the output waveform quality of the inverter;at the same time,it can suppress the leakage current of the PV power generation system and improve the reliability of the system.In order to further improve the utilization of input power and improve the voltage gain,this paper studies a three switch inverter based on the above inverter.In this paper,the working principle,device stress and common mode current of the two inverters in discontinuous mode(DCM)and hybrid mode(DCD)are analyzed in detail,and the voltage gain and power loss are analyzed and calculated in detail.The control strategy suitable for the proposed inverter is given.The causes of circulating current generation and zero distortion of output current are analyzed.The methods to solve the problem of circulating current and reducing the zero distortion of current are further studied.Then,the software and hardware parameters of the proposed inverter are designed and the inverter is simulated based on MATLAB / Simulink platform.Finally,two principle prototypes based on TMS320F2812 DSP are built and verified by experiments.