1.5kVA High Frequency Chain Single Phase Grid / Independent Dual Mode Photovoltaic Inverter

In the background of increasingly serious environmental pollution and energy crisis, the development and utilization of new energy is the trend of the times. The dual mode photovoltaic inverter, one of the most important components in photovoltaic power generation systems, was researched in this paper. This inverter is a key interface between photovoltaic power generation system and the load or grid. A 1.5k VA single-phase high frequency inverter based on the analysis of the circuit topology and control strategy was developed.First of all, the research status and development trend of the dual mode photovoltaic inverter were introduced. Based on the analysis of existing inverter topological structure and control strategy, the high frequency isolated booster and full bridge inverter level topology were chosen. The control strategy is voltage RMS control for off-grid mode and voltage inner loop, current outer loop for on-grid mode. The smooth switching control strategy from off-grid mode to on-grid mode and from on-grid mode to off-grid mode of the dual mode photovoltaic inverter was also presented.Then, the hardware design and software design of the dual mode photovoltaic inverter were given in details. The TMS320F28035 was chosen as the control core. The power circuit and control circuit of the inverter was designed, and the calculation method of the control circuit’s parameter, the design of drive circuit, the detection circuit, the protection circuit and the communication testing etc. were introduced respectively. The structure diagram of the system software was given for software design, including the main program, interrupt subprogram such as driving waveform generation and SPLL. Some important module’s source codes were presented as well.Finally, according to the design requirements, the experimental platform of the dual mode photovoltaic inverter was established, and a series of experiments were carried out. The inverter was tested on the off-grid mode, the on-grid mode respectively and the switch process between the two modes mentioned above. The experimental results show that the dual mode photovoltaic inverter meets the requirements of design.