Performance analysis of multilevel inverter with battery balanced discharge function and harmonic optimization with genetic algorithm

A single-phase 9-level cascaded multilevel inverter with SHE PWM, and battery balanced discharge functions is presented in this paper. Each H-bridge is connected to separate DC source and produce different voltage levels -V_dc, 0, +V_dc. Each cell voltage will differ apart over time. So always switch on the battery with highest voltage that is in descending manner. Then the discharging time is dramatically improved. Without the balanced discharge system, battery pack capacity will decrease quickly. The optimal switching angles is found by optimizing the non linear transcendental trigonometric SHE equations by using genetic algorithm. First, the operational principle of the system is explained to derive the design equation. The optimum switching angles of a cascaded multilevel inverter minimizing the total harmonic distortion is found by using genetic algorithm. Simulation results are obtained for single phase 9-level inverter with MATLAB/Simulink. Finally, a prototype is designed and implemented to verify the feasibility which will ensure excellent performance.