Research On Single-stage Boost Photovoltaic Inverter

Under the background of vigorously promoting new energy power generation,solar energy has attracted more attention for its advantages of high efficiency,non-pollution and no geographical restrictions.At the same time,photovoltaic power generation technology has also made great progress.However,the output voltage of photovoltaic panels is generally low.In order to enable the above voltage to meet the needs of electrical equipment or the power grid,the commonly method is to add a DC/DC boost circuit in the front of the inverters to form two-stage inverters.However,the traditional two-stage inverters have low integration,large volume and complex system design.Therefore,the study of single-stage boost inverter has practical significance.The dual-buck inverters solved many problems of traditional inverters,such as bridge arm through problem,power switches and power diodes can be optimized respectively,and the inverting circuit has high efficiency.But the inverter topology is buck inverters.Therefore,a single-stage boost inverter for photovoltaic power generation is proposed by adding a boost inductor and a diode at the input of the dual-buck half-bridge inverters.The single-stage boost photovoltaic inverters not only have the advantages of dual-buck inverters,but also have the boosting function.The working principle and steady-state characteristics of the inverter are analyzed in detail.The magnetic integrated inductance is introduced on the basis of the proposed inverters,which not only reduces the circulating current in the circuit,but also increases the power density of the inverters.And then,a switch is added to the proposed inverters.At the same time,a single-stage boost photovoltaic inverter without circulating current is proposed by using half-period SPWM modulation in this thesis.The working principle and the loss of each device in the circuit are analyzed.Secondly,a half-period SPWM modulation scheme for a high reliability single-stage boost Inverters without circulating current is proposed in this thesis.Furthermore,two control strategies of the inverter under different load conditions are studied.The simulation results under the direct control strategy are given.Then,the parameters of power devices in the inverter are designed.The sampling circuit the voltage and current are designed,which can generate unipolar half-wave signal.At the same time,the main programs based on AD RMS sampling,interrupt program are designed in the text.Finally,the simulation models of two kinds of single-stage boost photovoltaic inverter are built.And the principle prototype of two kinds of high reliability single-stage boost inverter based on the digital controller of TMS320F2812 DSP is also built.The simulation and experimental results verify the correctness of the theoretical analysis respectively.