A traveling-wave model of electric machines with eccentricity for shaft voltage analysis

Abstract

This paper presents a discrete model for rotor shaft and stator winding of an electrical machine. Multi-conductor transmission line theory is used for modeling connecting cable, stator winding, and rotor shaft. The conductors used in a stator winding are connected similarly to a multi-conductor transmission line using electrical and magnetic coupling effects. Modal theory is applied to the wave equations of the stator winding to obtain a discrete model for electrical machines winding. The voltage distribution in the stator winding, rotor shaft, and bearings were obtained by numerical simulation under symmetrical conditions and compared with published results for time-domain method. The consequences of a static eccentricity fault on shaft voltage were determined and evaluated using a symmetrical machine.

Electric drive systems with long feeder cables

“…where N is the number of turns in the coil, R c is the total resistance of the coil, L c is the total inductance of the coil, M is the mutual inductance, k is the coupling coefficient assumed to be 0.8-0.9, L 1 and L 2 are the leakage inductances of each turn/coil, C cg and C tg are the total coil to ground and the average turn-to-ground capacitance, respectively. The authors of [47][48][49][50] analysed surge voltage distribution and inter-turn voltage reflection of a stator winding by modelling it as a multi-conductor transmission line model. Consider the stator winding with n number of coils in four different regions as seen in Fig.…”

“…Equipotential line distortion in the cable due to conductor proximity[41] Cable current density distribution at different frequencies[42] Fig. 17 Distributed LC network model of multi-turn winding[45] Stator winding model considering overhang and slot regions[47] IET Electr. Power Appl., 2020, Vol.…”

Integral‐series Fourier analysis of chaotic PWM patterns for common mode voltage stresses

“…where c l θ is coefficient in the Fourier series along γ according to (29). In order to obtain the Fourier spectrum it is required that the coefficients are independent of the variable θ.…”

“…By replacing dummy variables x θ and X ω with c l θ and C l ω , respectively, and combining (29) to (33), integral-series Fourier spectrum of v γ, θ can be achieved…”

Survey on high‐frequency models of PWM electric drives for shaft voltage and bearing current analysis

“…The increment of slew-rate of input voltage leads to the injection of higher frequency harmonic components with lower wavelength, to a coil of an electric machine. Consequently, the phase shift per unit length and the distortion in the waveform may be increased [4]. The shaft voltage is the voltage difference between the drivingend and non-driving-end bearings in an electric machine.…”