Photovoltaic inverter is also known as power regulator. According to the use of inverter in photovoltaic power generation system, it can be divided into two types: independent power supply and grid connection. According to waveform modulation, it can also be divided into square wave inverter, step wave inverter, sine wave inverter and combined three-phase inverter. The inverter for grid connected system can be divided into a transformer type and a non transformer type according to whether there are transformers or not.
Inverter is a power adjustment device composed of semiconductor devices, which is mainly used to convert DC power into AC power.
It is generally composed of step-up circuit and inverter bridge circuit. The boost circuit increases the DC voltage of the solar cell to the DC voltage required by the inverter output control; the inverter bridge circuit converts the DC voltage after the boost to the common frequency AC voltage equivalent.
The inverter is mainly composed of transistor and other switching elements, which enables the DC input to be AC output by regularly switching the switching elements on (ON-OFF). Of course, the output waveform of the inverter generated by open and closed circuits is not practical.
In general, high frequency pulse width modulation (SPWM) is used to narrow the width of the voltage near the sine wave, the width of the voltage in the sine wave center is widened, and the switch element is always moving in one direction in a half cycle, thus forming a pulse wave column (quasi sinusoidal wave). then let the pulse wave form a sine wave through a simple filter.
