Abstarct: The goal of this project is to design an optimal fixed structure controller for multilevel inverter. For this purpose, one of novel multilevel inverter models namely Packed U-Cell (PUC) with consideration the aspects of the single phase multilevel inverters is investigated. Multilevel Pulse Width Modulation (PWM) technique is used to generate 7-level output voltage in this PUC. In this thesis, we intend to design an optimal controller for the PUC inverter so that the controller is more effective in stabilizing the capacitor voltage and generating a seven-level voltage in the output. In this thesis, in order to achieve the best performance of the controller, the multi-objective optimization algorithm is adopted to obtain optimal parameters of the controller. The performance of the proposed controller is investigated with simulations in different situations, such as load variations and variations of DC voltage source.