Three-phased multilevel inverter with identical step voltage levels for embedded systems

This paper presents three-phased inverter with three idencal step voltage levels. The main application is for embedded systems where the dc input voltage is stored in accumulator batteries. The input dc voltage is assumed to be a three identical series connection of accumulator batteries. The chosen inverter structure leads to minimise the necessary power switches. The voltage step levels and the switching angles are precalculated so as to delete the maximum number of low ranked harmonics and to optimise the fundamental magnitude which can be greater than the sum of the dc input voltage amplitude. The developped modeling approach leads to reduce the switching interval determination in [0, π/3]. The switching angles in [π/3, 2π] are deduced by symetrical properties of the ideal balanced three phase voltage system. This approach allows us to use, in the same time, a reduced number of switching per period and a small capacitance passive filter. Consequently, the total harmonics distortion (THD) in the output voltage, the power loses in the inverter are also reduced. Simulation results show a substantial increase of the fundamenal amplitude and a reduction of the total harmonique distorsion rate.