Induction cage machine supplied with voltage containing subharmonics and interharmonics

Abstract

This study deals with the influence of voltage subharmonics and interharmonics on an induction cage machine. The windings current subharmonics and interharmonics as well as the magnetising current are studied. The effect of voltage subharmonics and interharmonics on windings temperature rise is analysed. The results of measurements and calculations are compared for various machine models. The appropriate investigations are performed for two low-power, totally enclosed induction motors of different properties: a machine with a comparatively strongly saturated magnetic circuit, and one with a comparatively weakly saturated magnetic circuit.

Lowered voltage quality and load‐carrying capacity of induction motors

“…The power loss increases Δp i in each phase winding were calculated on the basis of current measurements in the reference tests and under lowered voltage quality. The power loss increases in rotor Δp r were calculated as a superposition of increases due to [29], and for motor g − on the basis of rotation speed measurement. The increases, Δp r− were calculated [4, 5] from the negative-sequence current value, which was determined on the basis of the measurements.…”

“…The other increases Δp i can be calculated with appropriate methods, e.g. presented in [4,5,12,21,[24][25][26][27][28][29]. Furthermore, the w i factors results from machine parameters (MP) and their quantifying require the thermal model of a motor [21].…”

“…The induction cage machines TSg 100L-4B (3 kW), Sg 132S-4 (5.5 kW), and mSZJe 34a (3 kW), denoted as machines α, β, and g, have built-in thermocouples in various parts: in end windings, slot windings, stator iron, under bearings, in inner air, and in rotors (machines β and g). The parameters of the examined motors are given in Table 2, and more detailsin [4, 5,21,29]. The three-phase AC power source Chroma 6590-3 of rated power 9 kVA enables the production of the voltage of the programmable waveform, precise set voltage, frequency deviation, and both magnitude and phase unbalance.…”

The analysis of output voltage distortion of inverter for frequency lower than the nominal

“…Voltage distortion is the factor which boosts energy consumption and generates additional thermal effects [12,14], therefore, works are underway with a view to reducing voltage distortion [15], as well as identifying its sources [16]. The basic tool used in the assessment of voltage waveform distortion is the frequency analysis that uses Discrete Fourier Transform (DFT) [2,4,7].…”

Analysis of the influence of selected non-linear devices on the waveform of supply voltage

“…The number of non-linear electrical devices is systematically increasing [3,7] because they usually offer lower energy consumption and better working conditions. Non-sinusoidal harmonic currents caused by non-linear devices may lead to significant distortion of supply voltage [8,9], which may cause disturbances in the operation of other equipment, particularly sensitive electronic equipment, worsening the energy consumption, and cause additional thermal effects [10,11]. Harmonic distortion reduces the power factor.…”