Economic design of sleeve rotor induction motor using rotor ends

In this paper, the field analysis of the sleeve-rotor induction motor taking the rings effect into consideration is carried out using the Maxwell’s field equations. A model in cylindrical coordinates is used to establish the rotor-rings and to solve the air gap magnetic field. The flux density is assumed to be constant through the very small air gap length while the skin effect through the axial rotor length is considered. The axial distribution of the air gap flux density, the sleeve current density components and the force density are obtained. The motor performance is carried out taking into account the effects of the sleeve rings performance characteristics. The effects of design data on the starting torque and the overload capacity of the motor are also considered.

A discharge estimator is designed and analyzed in this chapter to estimate the discharge with voltage, frequency and current without prior knowledge of head. A control of discharge in submersible pump is achieved by varying the motor speed. In VSI fed induction motor the speed is varied by varying the switching frequency. The ratio of frequency to the applied voltage is maintained constant, to keep the air gap flux at a desired value. The development of discharge estimator, PID and Fuzzy controllers are discussed in this chapter.

Diagnosis of faults in induction motor is an indispensable process in industries to improve the reliability of the machine and reduce the financial loss. Among the various faults occurring in induction motors (IM), bearing fault is the predominant one which covers nearly 60% of faults. In this paper, a study of the electromagnetic field of an induction motor with bearing fault fed from both the mains and a three phase voltage source PWM inverter in open loop is carried out using Finite element method (FEM). Electromagnetic field parameters like flux lines distribution, flux density distribution and radial air gapflux density are analyzed. The presence of bearing fault can be detected from the spatial FFT spectrum of radial air gap flux density. From the FFT spectrum, it is seen that the amplitude of fundamental component of radial air gap flux density decreases and those around 100 mm distance increases with the severity of fault.  

This paper presents a control scheme with an optimized air-gap magnetic field for five-phase induction motor, the control objective is to generate a quasi-square magnetic flux density by the control of excitation and torque currents in the two planes. In this paper, the decoupling vector control model of five-phase induction motor in d1-q1-d3-q3 coordinate system is analyzed, and the direct and quadrature current components in the third harmonic plane as non-linear functions of the fundamental are built, which guarantee the air-gap magnetic to be a constant quasi-square waveform irrespective of the mechanical load, and then the third harmonic current injected method for improved air-gap magnetic field is proposed. Finally, the simulations by Matlab/Simulink and experiments are implanted on a 5.5 kW, five-phase concentrated full-pitch windings induction motor. The results indicate that the proposed method can satisfy the requirement of a quasi-square air-gap flux density, and the air-gap magnetic field gets improved.

This paper presents the open-circuit magnetostatic field analysis of a DC commutator motor by applying 1-D and 2-D equivalent magnetic circuit methods. For the 1-D and 2-D equivalent magnetic circuit method, the average air-gap flux density of a DC commutator motor and magnetic flux in every node are derived respectively, and the validity is verified by the finite-element analysis. The Carter’s coefficient is applied to model the permeance of the slot and gear-teeth space. The differences of the air-gap flux density are 3.21% and 3.06% for 1-D and 2-D methods, respectively. The flux linkages, back-EMF constants, cogging torques, electromagnetic torques, and torque ripples of the two gear profiles with feasible number of teeth integrated on the rotor are analyzed to verify the effects of gear profiles. The result shows that the gear-teeth integrated on the motor act as dummy slots, which reduce the cogging torque and torque ripple by 92.02% and 50.14 %, respectively.

The influence of the semimagnetic stator wedges of different sizes on the electromagnetic characteristics and the behavior of the induction motor is investigated. The study will be carried out with both analytical calculations and FEM analysis. The analytical calculations will take into account the stator and rotor slots, as well as the iron core saturation in order to study the spatial and time-dependent harmonic content of the air-gap magnetic flux density and electromagnetic torque. The size of the wedge plays an important role as it determines the tooth tips saturation, the high harmonic content of the air-gap magnetic flux density, and the electromagnetic characteristics of the induction motor.

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.