Due to the accelerating crisis of the worldwide established fossil fuel and atomic energy system and the impact of green house gas emission led to the development of renewable generation units with medium voltage smart micro grids (e.g., 6- 36 KV). The cascaded H-bridge multilevel (CHBM) converters are considered as strong competitors for step-up transformer less direct grid integration. But due to the limited space of installation, high cost of failure and for reliable operation of converters, the power losses in semiconductor devices are required to be designed, analyzed and minimized. In this paper an improved precise loss calculation method is proposed and this method is utilised to calculate the power losses in a 28.6 MVA, 11KV, optimum level with reduced switching modes using bus-clamping pulse width modulation (BCPWM) for CHBM converter. All the analysis are performed in MATLAB environment with reduced harmonic distortion as well as switching losses.