Summary: A slip-ring asynchronous motor with permanent magnets built into the rotor yoke (SAS PM) is distinguished by the smooth start-up process. After start-up, motor self-synchronizes and operates as synchronous motor excited by magnetic field of permanent magnets. At synchronous operation the SAS PM has higher efficiency than induction motor. The article presents research of the mathematical model and simulations of two constructions of SAS PM motor: 6-pole rated at 1,7 kW and 4-pole rated at 14,5 kW. For the first motor the algorithm for electro-mechanic characteristics calculation during start-up and synchronous operation has been developed. Physical model of the motor was manufactured and calculation algorithm was verified. By using this algorithm, the start-up characteristic as well as electromechanical characteristic at synchronous operation for the second motor were calculated. Calculation have shown that motor with permanent magnets in „I” pattern has better properties at synchronous operation comparing to the motor with permanent magnets in „V” pattern.