Designing and Simulation of Grid Connected Inverter with LCL Filter

In this paper a grid connected inverter is designed in Linear Technology simulator LTSpice. Keeping in mind that the grid connected inverter is very expensive a cheaper and simple inverter has been designed. We use highly efficient MOSFET switching along with efficient op-amps. We have used zero-crossing detector circuit to detect the grid frequency and make frequency synchronization. A 12 volt solar power is provided by the DC source and 12 volts pure sine wave AC generated which can be step-up to required level. We have used a real time analog pulse width modulator generating pulse width modulated signal at 7.75 kHz. This PWM output is applied to the H-Bridge switching circuit to generate sine wave output hence this switching signal SPWM. The output of the H-Bridge output is analogous to the SPWM. This signal has been filtered to reduce the harmonic distortion. We have used an efficient LCL filter to minimize the harmonic distortion in the output of inverter. The output of our inverter has the total harmonic distortion 0.3%. A MOSFET driver helps efficiently operate the MOSFET at high frequency. The efficiency of our design is more than 98%.