A Simplified Analytical Averaged Model of a Thyristorized Commutatorless Series Motor

This paper proposes a simplified analytical averaged model of a thyristorized commutatorless series motor. The motor operation is generally complicated due to the complexities present in the three-phase synchronous machine used and the nonlinearities introduced by the switching operation of the power electronic converter that is feeding the electrical machine. The simple analytical model is formulated in light of a conventional dc series motor and is found to be approaching the simplicity of a conventional dc series motor both in dynamic condition and steady state. The developed simplified model is found to yield results closely tallying with those obtained from a "detailed numerical model" developed earlier, which is totally numerical in nature. The results are also validated experimentally on a small laboratory-built prototype. The developed model lays the foundation of controlling the motor for different industrial loading applications. One such application, viz., constant torque loading, is considered to show that the control strategy adopted on the basis of the discussed model works satisfactorily to develop a constant torque according to a given torque reference irrespective of load disturbances