The paper considers some problems of calculating spectral characteristics of magnetic
field of the linear induction motor (LIM), operating at the electrical braking modes. In automatic
drives with LIM the electric braking modes are usually applied: dynamic, recuperation, single –
phase, capacitor type, braking by means of opposite connection, by pulsating current and inverter
type (frequency) braking. During the process of braking in the moving part of the LIM and in some
cases in an inductor there are initiated complicated interrelated electromagnetic and
electromechanical non – stationary processes.
The braking processes have been analysed in the motionless right – sided Descartes system of
coordinates x, y, z. There have been presented the expressions of volumetric density of braking
current which have been regarded the non – periodic functions of coordinate x. Besides that in
cases of single – phase and capacitor braking these expressions are also regarded as the non –
periodic functions of time. Therefore when compiling the mathematical model there have been
applied Laplace and Fourier integral transformations. After having applied Fourier transformation
there have been received the expressions of the spectra amplitudes of primary magnetic field at the
dynamic braking under the condition that the number of excited zones in the inductor is even,
uneven and fractional. The continuous spectra of amplitudes have been calculated by the software
Mathcad 2001 Profesional.
Equivalent circuit of short rotor linear induction motor based on magnetic field analysis.
