METHOD OF STARTING AND SELF-STARTING OF SYNCHRONOUS MOTOR Russian patent published in 1994 - IPC

FIELD: electrical engineering. SUBSTANCE: increase of asynchronous moment under condition of start is achieved thanks to optimum control over excitation as function of electromagnetic torque. In this case acceleration of motor with the aid of starting resistor takes place in interval of change of sliding up to first preset value. In interval of change of sliding from first to second preset value excitation winding is cyclically changed over from resistance to exciter with two-polar forced voltage and back at moments when electromagnetic torque achieves correspondingly minimum and maximum instantaneous values. For computation of electromagnetic torque instantaneous values of phase currents and voltages of stator are used. In interval of slidings less than second preset value excitation voltage permanent by sign is fed and due to it motor is pulled into synchronism. EFFECT: improved starting characteristics. 2 dwg