This book does the following: 1- Study different UPS systems, and related subjects such as power electronics, and microcontroller unit. 2- Design and implementation of hardware circuits using microcontroller to get UPS inverter system meets the required performance and do the specified control. 3- Apply classical controllers such as PD, PID, and SMC using microcontroller and simulate these systems on simulation program, after that apply these controllers on the real system, and get experimental results. 4- Apply fuzzy logic control, and nonlinear PID-fuzzy control on UPS inverter system and simulate on simulation program, after that apply these controllers on the real system, and get experimental results.