The lack of variable-speed drives for two (single) induction motor is a reality. This article attempts mainly to investigate the reasons for this lack of variable-speed drives. This paper deals with literature survey of various existing converter topologies, which have been proposed for adjustable speed single phase induction motor drives. Various converter topologies have been compared in this paper. Among these converter topologies, the adjustable frequency PWM inverter is the best choice for single-phase induction motor drives. However, adjustable-frequency drives have not been widely used with single-phase induction motors. The open-loop constant V/F control law cannot be used with the single-phase induction motor drives as it is used with three phase motors. The variation of the operating frequency at lower speed range with constant load torque causes variation in motor's slip. A constant V/F control is suitable only over the upper speed range.

This paper proposed a new converter topology to drive induction motors. The proposed topology can boost the DC link input voltage in case of DC link voltage shortage without any additional converter. This converter employs two additional switches and one capacitor in each phase compared to conventional converters. Moreover, this new topology brings additional advantages such as less torque and current ripples and lower switching loss. After a discussion of the basic principles of operation, the dynamics of the converter is developed for control purposes.Simulation results are given to illustrate the associated advantages of the proposed converter.

In this paper, simultaneous estimation of the rotor speed and time constant estimation for a voltage source inverter–fed induction motor drive is discussed. Application of the Model Reference Adaptive System (MRAS) on the vector controlling of an induction motor drive in the rotor-flux-oriented reference frame is examined. Furthermore, to eliminate the offset error caused by the change in the stator resistance, a fuzzy resistance is also designed.

In this paper, a neural network model reference adaptive system speed observer is designed, which can be used inspeed control of linear induction motors (LIMs). Dynamical equations of LIM have been considered accurate. In otherwords, the end effect and the electrical losses of the motor have been included in the motor equivalent circuit. Thenequations of the reference model and adaptive model have been extracted. Existence of the speed-dependent functionsin the reference model causes error in speed estimation. In order to reduce error, the reference model equations areupdated unlike the standard MRAS method. The adaptive model equations have also been discrete and they have beenrewritten so as to be represented by a linear neural network (ADALINE). On this basis, the so-called back propagationhas been used to compute online, in recursive form, the machine linear speed. Finally, the estimated speed is used formotor speed control. The simulations show the efficiency of the method.

Electrical machine design involves solution of a number of non-linear equations. Due to the complexities of the problem, designers' experience still plays an important role in the design process.In this paper, three-phase induction motor design is considered as a non-linear system in which the input vector, consists of specifications and required performance. The output vector, on the other hand, includes physical properties and geometrical dimensions. Neural network is then used to simulate the non-linear system, describing the motor design problem. The proposed method enables the designer to design the motor without a knowledge of the relationships governing motor design. The proposed model is trained using data provided by a manufacturer and the results are compared with those obtained by conventional methods.

Vectorial control of the speed of an induction motor is an advanced speed control method, enabling us to control torque, magnetic flux individually as that of DC motor. This paper pre3sents, the effecting factors dominating on the motor &the primarily vectorial control, leading to an advanced model of control in various &arbitrary co- ordinate systems. Finally a biased field control method with/&without speed sensors, introduced & simulated.

An induction motor driving controller, with the aim of the reduction of energy consumption and minimum input power, has been developed. The shaft torque is calculated using the rotor flux and torque current component and then it is applied into the control system. For the purpose of energy saving, the magnetizing current is so determined that the required torque is produced at a maximum efficiency. A current regulator ensures the adaptability of the actual magnetizing current with its reference value; this results in the production of a stable torque at any desired load torque, even during the transient periods. According to simulation results, this controller can be suitable for drive systems of elevators and electric vehicles.

Increasing applications of electric motors and the environmental problems associated with the production of electric energy in Power plants, together with the rapid increase in energy cost necessitate the development of new methods for designing and constructing of energy efficient motor drives. Optimal control of motors efficiency by minimization of electrical losses is an effective means for realizing this purpose. In this paper, after presenting a dynamic model of 3-phase induction motors including copper and iron losses, the motor electrical loss is analyzed as a function of motor variables, and the conditions of its minimization are described. A new control system for finding the minimum loss point and as a result the on-line optimization of motor efficiency at variable speed and load is then proposed. In this system, a motor control variable changes continuously in search for the minimum loss point. This new method, in comparison with existing on-line loss minimization methods of induction motors, leads to a more energy saving and a smoother motor operation. The comparison of simulation results of a vector controlled induction motor under the proposed control system and a conventional control system confirms the superiority of the proposed system.