Fractal Approach for a High Resolution Multilevel Inverter

This paper presents a fractal based space vector pulse width modulation scheme for a high resolution multilevel voltage source inverter. In multilevel inverters, identification of the sector enclosing the reference space vector becomes a tedious process with increase in level of the inverter. An approach based on fractal geometry is efficiently utilized for sector identification and switching vector determination. Instead of using the conventional Cartesian coordinate system, hexagonal coordinate system is used to characterize the space vectors. This representation eliminates fractional arithmetic and makes the scheme computationally efficient. The switching vectors are directly determined from the hexagonal coordinates using simple arithmetic relations. Simulation results are presented for a 9-level inverter using open end winding configuration.