Control circuit analysis of photovoltaic junction box

1. At present, PWM integrated circuits are widely used in square wave output inverters, such as SG3525, TL494, etc. It has been proved that the inverter with high performance and price can be realized by using SG3525 integrated circuit and using power field effect transistor as switching power element. Because SG3525 has the ability to directly drive the power field effect transistor and has the functions of internal reference source, operational amplifier and undervoltage protection, its peripheral circuit is very simple.

2. Sine wave output inverter control integrated circuit, sine wave output inverter, its control circuit can be controlled by microprocessor, these microcontrollers have multiple PWM generators, and can set the dead time between the upper and upper bridge arms, using 80c196n to realize the sine wave output circuit, 80c196n completes the generation of sine wave signal, and detects the AC output voltage to achieve stability Press.

Selection of main circuit power devices of PV junction box inverter:

It is very important to select the main power components of inverter. At present, Darlington power transistor, power field effect transistor, insulated gate transistor and turn off thyristor are widely used. MOSFET is the most widely used device in small capacity low voltage system. Because MOSFET has low on state voltage drop and high switching frequency, I is generally used in high voltage and large capacity system GBT module, this is because MOSFET's on state resistance increases with the increase of voltage, and IGBT has a greater advantage in medium capacity system, while in extra large capacity system, GTO is generally used as power element.