Analysis of the Characteristics of an Electromechanical Starter in a Gas Turbine Plant

The article explores the possibility of using synchronous motors excited from permanent magnets (PMs) for electric starting of gas turbine powerplants (GTPPs) in gas transport systems. The two analyzed versions of the starter are one with radially magnetized inductor-surface-mounted permanent magnets (SPMs) and one with V-shaped inductor-core-interior-mounted permanent magnets (IPMs). The performance specifications entail that the starter has a multimode operation (hot start, dry run, gas–air flow duct flushing) in a short period of time and repeated short-time modes with target torque characteristics. The analyzed parameters of the compared rotor designs are magnetic flux distribution, harmonic composition of the field and counter-EMF, torque values and ripple, PM energy efficiency, and resistance to irreversible demagnetization. It is established that the SPM starter has a better torque density and overload capacity and weaker torque ripple and can be recommended for the electric startup of GTPPs with an increased inertia torque. The starter with an IPM rotor is preferable in terms of energy efficiency and ability to counteract the demagnetizing action of armature response. The technological difficulties of producing rotors with external magnets make it more complicated to use them in motors with high rotation frequencies.