Influence of the pulse‐width modulation control method on the performance of frequency inverter induction motor drives

Abstract

The methods of sinusoidal PWM voltage control, current hysteresis control, predictive current control and direct stator flux and torque control are briefly presented. The different operation principles are explained by block and structure diagrams. Their staiorflux and stator current trajectories are compared. The effect on the characteristic operational performance of induction squirrel cage motors is investigated. The harmonic losses of the stator and rotor winding and the torque oscillations are compared while considering the skin effect of the windings. Finally the torque response times are presented. The results are achieved by digital simulation and proved on a test stand with 22 kW induction motor and 30 kVA GTO frequency inverter.

Analytical Investigation of Influence of DC-Link Voltage Ripple on PWM VSI Fed Induction Motor Drive

“…[5] [6].But in this paper it will be shown that DC-link ripple voltage components may arise large torque ripple component with the same ripple frequency. The mathematical model is based on the mixed p-z approach [9] [10] [11].…”

“…Torque ripple with low frequency may become an important issue in induction motor drives .It cause mechanical oscillations, which are particularly dangerous in resonance frequencies of the system [5]. This torque ripple is usually superimposed to the torque ripple of switching frequency.…”

“…where symbol * means complex conjugate value By substituting (5) and (6) =T i0 (n,e)+ T i1 (n,e)+ T i2 (n,e)+ T iC (n,e) (8) where in (8) T i0 (n,e) is the electromagnetic torque without DC-link ripple component, T i1 (n,e) andT i2 (n,e) are part of the electromagnetic torque components respecting the DC-link voltage ripples and T iC (n,e) is the electromagnetic torque component from stator and rotor pulsation parts with very small value T iC (n,e)=0.These separate torque components can be seen from Fig.10. From Fig.11 we can see comprasion of the electromagnetic torque both for a constant DC link voltage and DEC-link ripple voltage.…”

Analytical closed-form investigation of PWM inverter induction motor drive performance under DC bus voltage pulsation

“…The expressions for the switching times in the normal SVPWM are given in [9]. Phase dependency is given by the function e e e π π π + = )…”

“…This dc bus voltage ripple affects the PWM output voltage waveforms, causing low frequency harmonic currents to flow into the motor. An increase in electric losses, excessive rise of the motor temperature, appearance of the torque pulsation, and noise problems as well as the dc-bus capacitor stress are just some of the possible problems [7], [9]. So, the analysis of the dc-link voltage pulsation and its influence on the motor performances is of great importance.…”