Browsing by Author "Mwasilu, Francis"

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    Fuzzy Model Predictive Direct Torque Control of IPMSMs for Electric Vehicle Applications
    (IEEE/ASME Transactions on Mechatronics, 2017-08-14) Justo, Jackson J; Mwasilu, Francis; Kim, Eun-Kyung; Kim, Jinuk; Choi, Han Ho; Jung, Jin-Woo
    This paper proposes a fuzzy model predictive direct torque control (FMP-DTC) strategy of interior perma- nent magnet synchronous motors (IPMSMs) for electric ve- hicle (EV) applications. The fuzzy logic control technique incorporated into the proposed FMP-DTC scheme dynam- ically determines the appropriate values of the weighting factors, and then generates the optimal switching states that minimize the electromagnetic torque and stator flux errors. Unlike the conventional model predictive (MP)-DTC strategy, the optimal switching states of the proposed FMP- DTC are selected without retuning the weighting factors. It means that they are updated depending on the specific operating conditions. Therefore, the proposed FMP-DTC is effective in various operating conditions that make it suit- able for the EV-traction operating environment. Hence, the proposed FMP-DTC method has a simple control structure and can explicitly handle the system constraints. The perfor- mance evaluation is carried out via both MATLAB/Simulink and a prototype IPMSM test-bed with a TMS320F28335 digi- tal signal processor (DSP). Comparative simulation and ex- perimental results present the evidence of the performance improvements based on the proposed FMP-DTC strategy compared with the conventional MP-DTC strategy by indi- cating a fast transient torque response, low ripples, and an accurate speed tracking even under rapid climbing or emer- gency braking situations.
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    Low voltage ride through enhancement for wind turbines equipped with DFIG under symmetrical grid faults
    (Journal of Engineering and Technology, TJET, 2018-12-31) Justo, Jackson J; Mwasilu, Francis
    In modern power systems with significant penetration of wind-turbines (WTs), improvement of low voltage ride through (LVRT) capability of WTs equipped with doubly-fed induction generators (DFIGs) is an important issue. Thus, this paper proposes a low voltage ride through (LVRT) strategy, which comprise of a capacitor connected in series with an inductor both connected in parallel to a resistor. The configuration is then connected to a small series resistor via a pair of antiparallel-Thyristors. The circuit and its switching control scheme of the proposed LVRT circuit are designed to: minimize the transition times, maintain the RSC connection to the rotor-windings, and reduce oscillations of dc-link voltage. In this case, the capacitor is entitled to eliminate ripples generated in the rotor voltage while the inductor reduces the ripple in rotor current. Different fault conditions were studied to validate the performance of the proposed scheme using MATLAB/Simulink platform. Comparative results and analysis are presented with conventional LVRT strategies.