Recommendations for Field Analysts in the Design and Optimization of Induction Motor

Induction motor optimization can be time consuming.  One of the parameters central to the design is slip, which changes greatly as the field analyst modifies the layout of the machine.  This was addressed in a paper, “Recommendatinos for Field Analysts in the Design and Optimization of Induction Motors,” by Kent R. Davey and Ray C. Zowarka that was presented at the Conference on Electromagnetic Field Computation (CEFC 2006) in May 2006.  Two notable contributions of the paper include (1) a method for computing power factor while modeling only 1/3 of one pole pitch of the machine, and (2) a method for minimizing the number of slip calculations required during design optimization by using equivalent circuit representations of voltage, torque, and rotor power dissipation.  The first contribution allows the designer to analyze the smallest sub-portion of the machine possible during optimization.  The second reduces the overhead required by numerous slip calculations.  The importance of introducing power factor into the optimization was also discussed.  A linear induction motor is the primary focus of this paper.

For further information, please contact Kent Davey.

The Equivalent T Circuit of the Induction Motor

The equivalent T circuit of an induction motor is found in every engineering motors book and is becoming increasingly important with the popularity of vector control.  The values used in the circuit are used to dictate the necessary gating signals for the pulse width modulated inverter.  It is the de facto standard bridge between the field analyst and the motor controller.  These parameters are not unique.  Force, energy, voltage, and secondary power dissipation can be shown to relate to the product of synchronous reactance and the coupling coefficient of the rotor and stator.  The mutual reactance, the secondary inductance, and secondary resistance are non-unique.  Yet this surprising feature can be used as a solution integrity check for the field analyst.  This was described in a paper, “The Equivalent T Circuit of the Induction Motor: Its Non-uniqueness and Use to the Magnetic Field Analyst,” by Kent R. Davey and presented at the Conference on Electromagnetic Field Computation (CEFC 2006) in May 2006. 

For further information, please contact Kent Davey.