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Simulation of railguns using the finite element method (FEM) is an alternative method for experiments, in the literature. Besides having many advantages, the FEM is complicated and time-consuming, especially for optimization. The circuit model method, unlike FEM, is simple, fast, and suitable for sensitivity analysis and optimization purposes. In this article, first, the circuit model is explained, and then, differential equations describing the behavior of the railgun have been derived and the equations have been solved by using the fourth-order Runge–Kutta method. The sensitivity of the railgun launching features to its parameters’ changes has been analyzed, which is an important issue that helps to design the railgun. Then, by using the particle swarm optimization (PSO) algorithm, single-objective and multiobjective optimizations have been done to maximize railgun outputs, such as velocity, efficiency, and force exerted on the armature at the moment of launching. Finally, for the validation of the proposed method, 3-D FEM has been employed. The results show the accuracy of the method. [ABSTRACT FROM AUTHOR]

The paper presents a novel technique for modeling ladder-secondary single-sided linear induction machines. Saturation effect is considered by core non-linearity characteristic for both primary and secondary. The proposed modeling method is based on magnetic equivalent circuit with adjustable accuracy. The machine parameters such as its dimensions, pole numbers, bar numbers, and also model accuracy can be chosen arbitrary in the proposed model. The end effect is considered by virtual teeth at the entry and exit ends of the machine primary. The results of the proposed method are compared with finite element method (FEM) in terms of accuracy and processing time. The results show the effectiveness of the proposed method. In addition, due to having long processing time of the FEM, the proposed method is a very suitable manner for modeling of this particular machine. Also, the accuracy of the proposed method has been confirmed by experimental results, in starting. [ABSTRACT FROM AUTHOR]

This paper presents a new method to model healthy and faulty wound-rotor induction machines (WRIMs) with and without inter-turn short circuit fault by a single set of equations. The model is presented for a machine with arbitrary pole, and rotor and stator slot numbers. A single set of equations, including both electric and magnetic parts, is solved to obtain full dynamic behavior of the machine. Therefore, the modified magnetic equivalent circuit with non-linear elements is used for modeling and a numerical technique is employed to solve the non-linear equations. The proposed modified method has a simple calculation procedure in comparison with the conventional magnetic equivalent circuit method. Solving the electric and magnetic equations by a single set of equations is the main advantage of the presented method, which is proposed for a WRIM machine, for the first time. In addition, to increase the accuracy, the saturation phenomenon is also considered in the model. Due to the saturation effect, there are some non-linear algebraic magnetic equations, which should be simultaneously solved with differential equations. A trapezoidal technique is used to convert differential equations to algebraic ones. To solve the non-linear equations, non-linear equations, Newton Newton–Raphson method is employed. Current signature analysis is used for rotor and stator inter-turn short circuit fault detection. Finally, the finite-element method is used to verify the effectiveness of the proposed modeling method. It is worth noting that the proposed method can model a healthy and faulty machine with different faults by a single model. [ABSTRACT FROM AUTHOR]