Development Of A PV Micro-inverter Based On ARM+DSP Structure

ABSTRACT:AS the core component of distributed photovoltaic system, photovoltaic (PV) micro-inverter has been the research hotspot. Many domestic enterprises are working on the mechanism of hundred watts PV micro-inverter. In this article, a micro photovoltaic inverter for independent photovoltaic module of200W is presented, and the details of the how the design was accomplished will be given.Firstly, this paper analyzed the basic structure of PV micro-inverter. Furthermore, based on the characteristics of micro photovoltaic inverter, this paper designs the structure of "high-frequency push-pull boost circuit+full bridge inverter circuit". Secondly, the mathematical model for push-pull boost circuit and full bridge inverter circuit are established. With the foundation of the mathematical model, the article designs the control strategy for PV micro-inverter and the circuit simulation for the PV micro-inverter by MATLAB software.After the success of simulation, this paper presents the prototype of PV micro-inverter. The design of the prototype includes DC-DC boost, DC-AC inverter and the circuit of control board. High-frequency push-pull circuit is used in DC-DC boost, while the peripheral circuit contains a push-pull transformer, drive circuit, DC signal acquisition circuit, and isolation circuit. DC-AC inverter adopts full bridge inverter circuit, and the service circuit includes isolation circuit, driving circuit, AC signal acquisition circuit and isolation circuit. In the PV micro-inverter system, the structure of "ARM+DSP" is used as the core of control. The ARM is responsible for boost control and DSP is responsible for control inverter. The close-loop control strategy was realized by C language.Finally, this paper proceeds experiment for PV micro-inverter and analyses the output waveform and data.