This project deals with increasing efficiency of one phase induction motor with permanent split capacitor. We can whole thesis divide into two parts, the first one is basic and the second is interested in analysis and measurement. First part handles with construction of single phase induction motor, explanation of function principle, start and run of motor. Calculating of efficiency including type of losses, which reduce efficiency. Second part concerns analysis losses including moment load characteristic, motor measurement while rotor is locked, with no load operation, measuring mechanical and additional losses. Further there will be measured useful values for creation model for simulation (reactance of windings etc.). Than will be the model created in ANSYS Maxwell with module RMxprt. After analytic calculation in RMxprt and using Finite Element Method (FEM) load characteristics will be compared together. This comparison gives us information about accuracy of model for simulation. Simulation and measurement will be carried out on another engine with high quality ferromagnetic material used for magnetic circuit of motor. Further will be done simulation of motor with modifications shown in previous chapter for high efficiency.