Chinniah B. Rajanathan

Finite element aided design optimisation of a shaded-pole induction motor for maximum starting torque

A method of optimizing the design of a shaded-pole induction motor for maximum starting torque with the aid of finite element modeling and a modified hybrid global-local search method combining the niching genetic algorithm with a direct search method is presented. By invoking the genetic algorithm and the deterministic method in turn, the solution with the global minimum is secured while simultaneously improving the convergence speed. The performance of the hybrid search method is demonstrated with an ideal mathematical problem first, before applying it to the shaded-pole motor design.

Simulation of a single phase induction motor operating in the motoring, generating and braking modes

A computer simulation of the single phase induction motor operating in the motoring, generating and braking modes, using 2-D finite elements is presented. Simulation as a motor includes operation from a nonsinusoidal power electronic supply. In the generating mode with capacitor excitation, the transient build up of terminal voltage is treated with a small permanent magnet in the rotor to account for the residual magnetism. In the braking mode with capacitor aid the motor speed is determined by the solution of the coupled electromechanical equations of motion. The finite element model uses a single pole-pitch model with the rotor sector executing a to and fro reciprocating motion.

Transient characteristics of the single phase permanent magnet synchronous motor

A time stepping finite element modelling technique, which can accurately represent the single-phase synchronous motor with a permanent magnet rotor, is presented. The modelling allows the rotor to move with respect to the stator at each time step, and the spatial angular step is determined by the solution of the equations of motion and the computed electromagnetic torque. The model is voltage driven and no restriction on the time variation of the applied voltage is imposed. The magnetic nonlinearity of the stator iron is taken into account in the field equations describing the electromagnetic field of the motor.

Design and control of an electromagnetic actuator without mechanical springs

The paper describes a new form of actuator that depends on eddy currents for its operation. Its design with the aid of computational electromagnetics taking account of the external power supply and thermal effects is presented. The variation of the thrust with displacement of the actuator is shown to depend largely on one design parameter. It is shown however that this restriction can be overcome by modulating the exciting voltage as a function of the actuator displacement in real lime, The control is achieved by the use of DSP hardware and software. The need for a mechanical spring is eliminated by the design employing a single conducting tube with two stators.

Electromechanical transients in a three-phase induction motor during phase failure and plugging

A transient, two dimensional finite element study of a 3-phase, delta connected squirrel cage induction motor is presented. The cases considered are sudden loss of all three supply lines, loss of a single line, loss of a phase winding on a balanced supply and braking by plugging. The ensuing behaviour of the motor is predicted by the step by step solutions of the electromagnetic field and mechanical equations of motion. In all cases the transients in speed, torque and currents are presented and discussed. The finite element analysis models only a quarter of the 4-pole induction motor and includes rotor mesh movement in discrete steps.

A method of reducing errors in the calculation of electromagnetic forces by Maxwell stress summation method

The errors involved in the calculation of forces by Maxwell stress summation are examined and a method of improving the accuracy is presented. The method transforms the standard integration into a summation of forces acting on elemental edges in the region of integration after applying a field correction. Three test examples, two of which have analytical solutions are available, are used to show the effectiveness of the method proposed.

Finite element aided design and development of a new form of actuator

The development of a single-phase induction actuator using finite element modelling is described. An initial prototype designed by intuitive reasoning is examined and improved upon. The complete problem of coupling the electrical supply, the axisymmetric field of the actuator and its mechanical movement is considered. >