I am trying to do a inverter using ferrite core transformer, but the problem is the frequency output from the ferrite core transformer, If I am using that, I will be getting 230V AC but the frequency is much higher >10KHz. Please guide me to obtain 230V, 50Hz AC supply from ferrite core transformer.
The ferrite transformer is for a DC-DC boost converter working at 50-200 kHz. The 12V is boosted to 230V DC. An oscillator creates a 50 Hz PWM signal modulated onto the boost converter output. This is fed into an H-bridge. The output from the H-bridge is still a square wave (centered at 0V) with a 50-200 kHz carrier frequency, but modulated to 50 Hz. Output inductors and capacitors can be used to make a low pass filter to convert this to true sine wave, but is usually not done in most cheap UPS. This is not a problem for most types of loads.
Here is a video on the PWM scheme https://www.youtube.com/watch?v=hJqD9-HFULA
The other option is to use an iron core transformer and feed it a sine wave using power transistors. This is what is present in currently available cheap UPS on the market.