How calculate power drop or consumption across IGBT in 4Q converter input voltage is 1070 v dc nd o/p is 690vac.?

Try the major IGBT manufacturer's websites. I know that Infineon, Fuji and Mitsubishi offer loss calculation applications on their website. It is possible to work out different configurations and PWM parameters and obtain losses for each of these cases. It will, however, be necessary to register before gaining access to the applications, but it is worth it in my opinion.