Circuit Torque Research Articles

Equivalent circuit and characteristic simulation of a brushless electrically excited synchronous wind power generator

A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with two different sets of windings with different pole numbers, and a hybrid rotor with powerful coupling capacity. The pole number of the rotor is different from those of the stator windings. Thus, an analysis method different from that applied to conventional generators should be applied to the BEESG. In view of this problem, the equivalent circuit and electromagnetic torque expression of the BEESG are derived on the basis of electromagnetic relation of the proposed generator. The generator is simulated and tested experimentally using the established equivalent circuit model. The experimental and simulation data are then analyzed and compared. Results show the validity of the equivalent circuit model.

Reduction of Numerical Errors of Time-Stepping Finite Element Analysis for Dynamic Simulation of Electric Machines

The time-stepping finite element method (TS-FEM) can couple the magnetic field, electric circuit and mechanical torque balance equations together and has been widely used to simulate the dynamic characteristics of electric machines. Despite its heavy computational burden, the accuracy of TS-FEM is still limited by a host of practical constraints. Also, it is difficult to accurately model the sliding surface of the stator mesh and the rotor mesh in rotating electric machines. In this paper, a curvilinear element to approximate the curved geometry of sliding surface is presented to increase the computational accuracy. To reduce the numerical error of the derivative quantities, a modified nonlinear iterative formulation is adopted. To reduce the computing time, an adaptive time step size algorithm is also proposed. The proposed strategy and algorithm are verified by the FEM examples as reported in this paper.

ANALYSIS OF A SERIES-DELTA CONNECTED TANDEM INDUCTION MOTOR

Abstract A tandem induction motor comprised of two independently housed stator windings, one housing stationary and the other able to be physically rotated, and a squirrel-cage rotor common to both stators is described. When the motor is fed from a single source, altering the position of the moveable stator changes shaft speed in a similar manner to operating a normal induction motor at variable terminal voltage This paper presents an equivalent circuit model of the tandem induction motor for series-delta connected stator windings. Using the equivalent circuit stator current, power factor, and torque are calculated and then compared to laboratory test results obtained from a 3 kW tandem motor test rig