The article is devoted to the experimental investigation of the influence of load regimes on the spectrum of induction motor current . Spectrogram analysis allows to identify the presence of deterioration and to determine the operating mode of the induction motor. The experimental apparatus described in the paper allows to measure motor current oscillogram and calculate its spectrum. The appratus is based on PIC highspeed microcontroller. For current measuring the Hall sensor ACS712 is used. Several experiments are carried out in the research: without load, with load, with shaft beating imitaion. The analys of collected data has shown that the spectrums has some differences depends on the type of motor load. The research may be used for diagnostic system for inductor motors.

Keywords: Induction motor, current sensor, microcontroller, current spectrum, fast Fourier transform.

The experiments by obtaining 3-phase stator current oscillograms under different emergency regimes are described in article. For this purpose an experimental equipment has been used. It included current sensor, multi-channel ADC board, special block for emergency regime simulation and computer. For data processing MathCAD soft has been used. With Fast Fourier Transform algorithm the spectrum graphs were built. Analyse of spectrums showed the differences in odd harmonics between ordinary and any of emergency regime. For analyse the 0-1 kHz frequency range was taken. The research has shown that this technique can be used in diagnostics of 3-phase motors. General algorithm for real-time diagnostic system is developed.

Keywords: Three-phase induction motor, the current sensor, spectral analysis, harmonic, fast Fourier transform

In this article is reviewed the mathematical model of the stepper motor. Analysis of mathematical models showed the presence of oscillation the impulse response, thereby requiring backup duration of the control pulse. The work provides an example the realization of algorithm for calculating a minimum time for one cycle of operation of stepper motor. The results of these studies can be used in the stepper motor control system to increase speed and reduce power consumption associated with the stepper motor control.

Keywords: stepper motor, mathematical model, the transfer function, damping coefficient, differential equation, the recurrence solution iterative solution