The feasibility of constructing composite rotors in the laboratory for use on a 60- to 120-Hz supply has been established and the experimental results with such rotors have been published for the first time. Results obtained from the tests made on a three-phase induction motor with different solid-iron as well as composite rotors are presented. These are compared with the theoretically predicted characteristics based on existing analytical as well as numerical analyses.

Solid-Rotor and Composite-Rotor Induction Machines

To improve upon the performance of high speed solid rotor induction motor, composite rotors were constructed by depositing the layers of Cu+(Fe-Co) and Cu+(Fe-Ni), in few tens of microns. Performance was evaluated through the equivalent circuit approach, the parameters of which were determined only by no load and blocked rotor tests on the machines at 400 Hz. The torque and the torque per unit current increases significantly on the composite rotors. All the computed performance characteristics at 400 Hz have been presented in this paper. The complex dependency of the rotor parameters on slip has been clearly brought out. The improvement of overall performance of the composite rotor induction motor has been predicted.

Experimental investigations on high speed solid and composite rotor induction motor

The interaction between the eddy currents induced in the solid cylindrical rotor steel structure and the revolving field of the airgap produces the electrodynamic torque. The polyphase induction machine with solid-iron rotor offers advantages in ease of manufacture, in high torque per ampere at standstill, in withstanding high rotational stresses, and in operating in unusual environments. It is the purpose of this paper to present an approximate three-dimensional nonlinear numerical analysis of the solid-rotor induction motor for finding the three-dimensional current-density distribution in the solid rotor, in order to calculate the performance characteristics, based on finite-difference iterative techniques.

https://repository.library.northeastern.edu/files/neu:330691/fulltext.pdf

Current-density distribution in solid-rotor induction motor

In this paper a simplified model of the solid-rotor induction machine is discussed. Analysis is provided on the basis of Maxwell's equations yielding a dimensionless thrust-slip characteristic which permits rapid evaluation of various machine parameters in its performance. The salient feature of this kind of induction device—flat thrust-slip response—is borne out by the obtained curves.

Electrodynamics of solid-rotor induction machines

The paper records a study of an investigating the performance of a solid-rotor induction motor with a rectilinear inverter excitation to identify the effects of the associated time harmonics. The performance is determined experimentally by using a stator of a three-phase laboratory induction motor that is fitted with a solid-steel rotor and compared with the theoretical model developed which uses the Fourier components of the supply voltage waveform. Final conclusions are drawn from comparing motor performances with sinusoidal and inverter excitations. An equivalent circuit model is developed to determine the harmonic currents. The development of the theoretical model make use of the results of existing field analyses. Harmonic currents and other performance details including the possible interactions between the co-existing harmonics are determined and discussed. The measured values of torque, input current and power over full speed range with the two types of excitation are presented, and compared with the theoretical values. The waveforms of current, phase and line voltages are analyzed experimentally and compared with simulation results. The theoretical results correlate well with measured results and the significant harmonic effects are identified. Solid-Rotor ! \" # $ %&'() # * + , -'#.* /* # 0 1 2 3 ) %&') # * 45 6 7( (. )# \" ' 8 7 5 ' '# 2 9' :( (; ( : # (* -'( & 7 5 ' 7 < < = 9 Fourier Components ! %&'() (# * ( 6 %&') # * \"# # # * 7 5 ' '. ; #>'? -' ' @ 6 # ( 7( (. '# ' #A >*'& , > 9 -'#.* 6 (# B>'( 7 5 ' 7 < = 9 # * -@' 6 #( ( -45 C# ' # 'D -'#.* '# '? C;' '? ' 7 # , -'#.* 6 2 , . 78) '# & '. . (& 1( (# = 7#. B>' : ; '?+ 2 7 ; E # $ #2 4& 2 F 6 '(# ( # = B>' : ; '# 5 '? # 7 5 # * 6 # &C -.D # = B>' ? # & # 0 # 7 # ) 7#. : -'#.* 6 EFFECT OF HARMONICS ON A SOLID-ROTOR INDUCTION MOTOR A. M. Saleh and A. Th. Radhi

Effect of Harmonics on a Solid-Rotor Induction Motor

This paper discusses the results of tests made on a 3-phase solid iron rotor motor and substantiates simple design equations that give a clear understanding of the motor performance. From this understanding, areas in which the motor could be exploited are suggested, and it is concluded that the solid rotor machine has characteristics that are particularly suitable for solid-state power controls.

Leo A. Finzi

Papers

Analysis of the Solid Iron Rotor Induction Motor for Solid-State Speed Controls