An inverter is a power adjustment device composed of semiconductor devices. It is mainly used to convert DC power to AC power. It is generally composed of a boost circuit and an inverter bridge circuit. The boost circuit boosts the DC voltage of the solar panels to the DC voltage required for inverter output control; the inverter bridge circuit equivalently converts the boosted DC voltage into an AC voltage of a common frequency.
According to the application of the inverter in the photovoltaic power generation system, it can be divided into two types: off-grid inverter and grid-connected inverter. According to the waveform modulation method, it can be divided into square wave inverter, step wave inverter, sine wave inverter and combined three-phase inverter. For inverters used in grid-connected systems, they can be divided into transformer-type inverters and transformer-less inverters according to the presence or absence of transformers.
The inverter not only has the function of DC and AC power conversion, but also has the function of maximizing the performance of solar panels and the function of system failure protection. In summary, there are automatic operation and shutdown functions, maximum power tracking control function, independent operation prevention function (for grid-connected systems), automatic voltage adjustment function (for grid-connected systems), DC detection function (for grid-connected systems), and DC ground detection function (for grid-connected systems).