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All Journal International Journal of Electrical and Computer Engineering International Journal of Applied Power Engineering (IJAPE)
Damian Benneth Nnadi
University of Nigeria
Computer Science & IT Electrical & Electronics Engineering

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Multi-phase inverter-controlled induction machine at varied rotor parameters Crescent Onyebuchi Omeje; Damian Benneth Nnadi; Stephen Ejiofor Oti
International Journal of Electrical and Computer Engineering (IJECE) Vol 12, No 5: October 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v12i5.pp4808-4819

Abstract

This paper presents a step-wise modelling of a symmetrical six-phase induction machine driven by a six-phase diode clamped multi-level inverter at a varying rotor resistance and motor inertia. The machine drive process was considered in two stages. The first stage presents the dynamic behavior of the machine when a load torque of 0 Nm and 100 Nm is applied at a varied rotor external resistance value of (0.8 and 3.2) Ω with constant motor inertia. The second stage showcased the variations in the speed, electromagnetic torque and rotor current when motor inertia is varied at (0.5 and 1.5) Kg-m2 with rotor resistance held constant. A six-phase five-level diode clamped converter phase displaced by sixty degrees with a modulation index of 0.8 was modeled to drive the poly-phase machine at a reduced %THD. All machine models were simulated in MATLAB 7.11. The simulation results showed that reduced oscillations in rotor current, motor speed and torque pulsations were achieved at a varied external rotor resistance and motor inertia.
Power loss minimization assessment of a doubly fed induction generator with variable core resistance for wind turbines operation Crescent Onyebuchi Omeje; Damian Benneth Nnadi
International Journal of Applied Power Engineering (IJAPE) Vol 11, No 4: December 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1671.504 KB) | DOI: 10.11591/ijape.v11.i4.pp304-318

Abstract

This paper assesses the efficiency level and power loss minimization of a doubly fed induction generator (DFIG). A modified DFIG equivalent circuit with multi-core resistance connected in parallel was adopted. State-space differential equations of the DFIG was developed incorporating iron and copper loss components while a minimum flux linkage that aids in the minimization of the overall losses was derived. Simulation results showed that losses were minimized when the equivalent core resistances were connected in parallel with minimum permissible current flow. The results obtained during a transient disturbance showed that at different core resistance values of Rfe = 0.75Ω and 0.25Ω, different efficiency values of 83.45% and 41.21% were realized. An unconstrained optimization test carried out on the DFIG variable parameters showed that the DFIG power loss model was controllable with a positive definite value of 691.9801 and 2.9156〖e〗^(+5) for the leading principal determinants of the Hessian matrix. All simulation processes were achieved in MATLAB/Simulink 2020.
Co-Authors Crescent Onyebuchi Omeje Stephen Ejiofor Oti