Hello Dear, How can i make 400V, 1000W fluorescent ballast. Which ICs product i use. Could you help me, please. Best Regards, Thank you.

[MGULE.1]

Look at the International Rectifer(Infıneon) Ballast Designer Program, which is highly recommended to use for ballast circuits in great case for long time use and use mainly IR2520D and L6561/L6562D Ic Models.

By the way, for Ballast design over 40W, you should deal with PFC IC/Circuits for more realible and stable in each Grid Voltage Levels.