5kW Singie Phase Photovoltaic Grid-coilnected Inverter Hardware Circuit Design

Along with the development of human society, people’s demand for energy is increasing. While the shortage of energy turns out to be the key factor that restricts the development of the society. the drying up of fossil energy sources and the worsen of the environment due to pollution make the searching of new energy sources the focus of development in all the countries nowadays. Among those new energy sources, the photovoltaic power generation attracts a great deal of attention for its strong points like the short construction term, no pollution, no noise and so on. The photovoltaic power generation has now become a new trend of energy application.Based on the advantages of the photovoltaic power generation, and the previous experiences of the design of photovoltaic grid-connected inverter, Development of a photovoltaic grid-connected inverter prototype with the calculating method of getting the maximum power of the variable step length based on the average power. The power conversion efficiency of the inverter will be increased and the overtone produced by the on and off of the power tube will be reduced by maximum through the SPWM(Sinusoidal Pulse Width Modulation) modulation. After that, emulation and analysis to the adjust and control of loop PI(proportional integral) and control of loop proportional based on the SPWM,than choose DC side voltage control current which will help to enhance the stability of the inverter system.Considering the control method of the inverter system, the inverter hardware circuit design can be divided into control board, sampling board and power board, among which the circuit design of the power board is of great importance and difficulty. The power board gives detailed information of the DC filter circuit, the AC filter circuit and the specific design of the various sampling circuits. MCU in the control board uses the TI company’s DSP chip TMS320LF2407which is the core and forms the external circuit to fulfill the aim of controlling system’s stability and accuracy. The sampling board gives the designing circuit parameters of the auxiliary power supply.The experimental prototype of the single-phase photovoltaic grid-connected inverter with a power of5kW has been made and a series of experiments has been conducted by this prototype. In the process of debugging, we constantly improve the control method of the system and the filter circuit in the power board, to get the ultimate desired results.