New approach for the analysis of a three-phase induction motor of different ratings connected to a single-phase supply

The problem of operating a three-phase induction motor connected to a single-phase supply system using two convertors is discussed. Special attention is focused on the starting torque and minimum unbalance requirements for different motor power ratings. A new approach is suggested concerning the calculation of the starting and running sizes of the convertors, to enable the motor to start under full load conditions with minimum unbalance factors. These sizes are also modelled as functions of the motor power, with a wide applicable range. A method of determining the switching instant of the first convertor sizes is also introduced and modelled. Numerical application of the proposal is carried out on different induction motors to investigate its validity