ABSTRACT:The steady state stability analysis (SSSA) is done using small perturbation model. This study presents a detailed steady state stability analysis (SSSA) criterion based on small perturbation model of a adaptive neuro-fuzzy inference system (ANFIS) based current source inverter fed synchronous motor (CSIFSM) drive system taking d-axis and q-axis damper winding into account using ANFIS model. The modeling also clearly shows that even at no load the system satisfies steady state stability analysis (SSSA) criterion. Using the concept of Park's transformation the armature current in d-q model has been represented by suitable equations as a function of armature current magnitude in phase model (I S ) and the field angle (β). As the system under consideration is basically a current source inverter fed system, I S has been considered as a constant and as a consequence the field angle (β) finally appears as a control variable. The modeling of the system has been done using adaptive neuro fuzzy inference system (ANFIS) by considering the input parameters; inductance (L) and inertia of the rotor (J rotor ) and output as steady state time. The analysis concludes that the absence of damper winding leads to instability of the machine system. This paper describes the fuzzy modeling of CSI fed synchronous motor for studying its steady state stability analysis. The effect of winding parameters on the steady state performance of the synchronous motor is incorporated in this study. Fuzzy models were developed using adaptive neuro-fuzzy inference system (ANFIS). It is observed that system Moment of Inertia (MI) has a significant effect on optimal winding inductance to achieve steady state operation in shortest period of time. The winding leakage inductance should be reduced for achieving steady state operation in shortest time. KEYWORDS: ANFIS, Fuzzy Logic, ANN, Simulink, Current source inverters (CSI), Synchronous motor(SM) I. INTRODUCTIONThe models of synchronous machines widely employed in various areas play important roles in many studies such as stability and control analysis. Generally, the synchronous machine is a very complex non-linear system with dynamics and non-linearities that cannot be modeled in precise mathematical terms. In order to accurately model the machine, non-classical techniques are needed. Fuzzy logic modeling, neural network and adaptive neuro-fuzzy inference system (ANFIS) modeling have proposed as viable alternatives. These two innovative modeling approaches share some common characteristics: they assume parallel operations; they are well known for their fault tolerance capabilities; and they are often called model-free modeling approaches. On the other hand, neural network modeling is based on artificial neural networks (ANN) that are motivated by biological neural systems. Because of very origins, the respective philosophies and methodologies underlying their problem-solving approaches are quite different and, in general, complementary. As a result, many researchers are trying to integrate th...

Steady state stability criteria of A.C. drives play a dominant role for making the drive system practically successful. Generally such steady state stability analysis (SSSA) is done using small perturbation model. This study presents a detailed steady state stability analysis (SSSA) criterion based on small perturbation model of a fuzzy based current source inverter fed synchronous motor (CSIFSM) drive system taking d-axis and q-axis damper winding into account using fuzzy set theory. The modeling also clearly shows that even at no load the system satisfies steady state stability analysis (SSSA) criterion. The current source inverter fed synchronous motor (CSIFSM) has been treated as a five coil primitive machine model using the concept of generalized theory of electrical machines. Using the concept of Park"s transformation the armature current in d-q model has been represented by suitable equations as a function of armature current magnitude in phase model (I S ) and the field angle (β). As the system under consideration is basically a current source inverter fed system, I S has been considered as a constant and as a consequence the field angle (β) finally appears as a control variable. Finally the transfer function Δβ (s)/ΔT L (s) have been formulated; where Δβ (s) and ΔT L (s) represent small change in transformed field angle and load torque, respectively. A fuzzy logic system is developed for steady state stability study of CSI fed Synchronous Motor (CSIFSM) and discussed for its better performance. The analysis concludes that the absence of damper winding leads to instability of the machine system.