계통의 불평형 조건에서 동특성 개선을 위한 DFIG 풍력발전시스템의 새로운 제어전략

Francis Mwasilu,노경수 대한전기학회 2012 대한전기학회 학술대회 논문집 Vol.2012 No.7

Finite Set Model Predictive Control of Interior PM Synchronous Motor Drives With an External Disturbance Rejection Technique

Mwasilu, Francis,Nguyen, Hoach The,Choi, Han Ho,Jung, Jin-Woo IEEE 2017 IEEE/ASME transactions on mechatronics Vol.22 No.2

<P>This paper designs a predictive speed controller of interior permanent-magnet synchronous motor (IPMSM) based on finite control set (FCS)-model predictive control (MPC). The proposed predictive speed controller has a cascade-free structure that comprises a single predictive control function for the speed and dq-axis stator currents. The future rotor speed and stator currents are predicted at each sampling interval. Then, the proposed predictive control function is evaluated to determine the optimal switching states for the IPMSM drive. In high-performance speed-controlled drive, the unknown load torque disturbance has to be suppressed. Therefore, the load torque disturbance estimator using the two-stage extended Kalman filter (TSEKF) is proposed to enhance the dynamic performance of the IPMSM drive. The proposed TSEKF simultaneously estimates the system states, which greatly improve the model prediction process. The proposed predictive speed control is simple and compact, which demonstrates a faster transient response and a robust feature to mechanical system parameter variations when compared with the conventional cascaded speed control under a wide speed range and load torque variations. The experimental results on a prototype IPMSM drive built on a Texas Instruments TMS320F28335 floating point digital signal processing (DSP) board are presented considering the constant torque and flux-weakening regions to confirm the feasibility of the proposed FCS-MPC scheme.</P>

Finite-Set Model Predictive Control Scheme With an Optimal Switching Voltage Vector Technique for High-Performance IPMSM Drive Applications

Mwasilu, Francis,Kim, Eun-Kyung,Rafaq, Muhammad Saad,Jung, Jin-Woo IEEE 2018 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS - Vol.14 No.9

<P>This paper investigates a high-performance finite-set model predictive control (FS-MPC) based on an optimal switching voltage vector technique for voltage-source inverter (VSI)-fed interior permanent magnet synchronous motor (IPMSM) drives. The proposed algorithm clamps one switch that supplies the largest phase current at each sampling interval while allowing the other two pole switches to remain active. Unlike the conventional FS-MPC scheme, the proposed scheme involves only two voltage vectors to obtain an optimal switching state with reduced switching losses and low computational cost without incorporating any additional parameters or constraints in the cost function. Thus, the proposed FS-MPC implemented on a DSP-based prototype exhibits high performance features (low switching losses and low harmonic distortion above rated speed) in constant torque and power regions. The experimental results on prototype VSI-fed IPMSM with TMS320F28335 are presented under various conditions to demonstrate the efficacy of the proposed scheme compared with the conventional FS-MPC.</P>

Enhanced Fault-Tolerant Control of Interior PMSMs Based on an Adaptive EKF for EV Traction Applications

Mwasilu, Francis,Jin-Woo Jung IEEE 2016 IEEE TRANSACTIONS ON POWER ELECTRONICS - Vol.31 No.8

<P>This paper proposes an enhanced sensor fault-tolerant control (FTC) scheme of an interior permanent magnet synchronous motor (IPMSM) drive for the electric vehicle (EV) traction applications. For a safe and continuous operation of the modern EV, the drive has to acquire robustness features for position sensor failures. Hence, the proposed FTC is based on an adaptive extended Kalman filter (AEKF), which continuously estimates both the states and covariance matrices that describe the statistic characters of the system. Under a position sensor failure, the proposed FTC scheme instantly detects sensor fault and reconfigures the traction system with a virtual sensor to provide an EV with a necessary limp home capability. Unlike the conventional EKF with fixed covariance matrices, the proposed AEKF exhibits the robustness to the system stochastic noises and the transient operating conditions. Simulation on MATLAB/Simulink and experimental results on the IPMSM test bed with a TMS320F28335 DSP under various transient operating conditions are presented to demonstrate the effectiveness and feasibility of the proposed FTC scheme in comparison to the FTC with the conventional EKF. The comparative results indicate that the proposed AEKF more precisely estimates the rotor position with features robust to the position sensor failures than the conventional EKF.</P>

An Observer-Based Optimal Voltage Control Scheme for Three-Phase UPS Systems

Eun-Kyung Kim,Mwasilu, Francis,Han Ho Choi,Jin-Woo Jung Institute of Electrical and Electronics Engineers 2015 IEEE transactions on industrial electronics Vol. No.

<P>This paper proposes a simple optimal voltage control method for three-phase uninterruptible-power-supply systems. The proposed voltage controller is composed of a feedback control term and a compensating control term. The former term is designed to make the system errors converge to zero, whereas the latter term is applied to compensate for the system uncertainties. Moreover, the optimal load current observer is used to optimize system cost and reliability. Particularly, the closed-loop stability of an observer-based optimal voltage control law is mathematically proven by showing that the whole states of the augmented observer-based control system errors exponentially converge to zero. Unlike previous algorithms, the proposed method can make a tradeoff between control input magnitude and tracking error by simply choosing proper performance indexes. The effectiveness of the proposed controller is validated through simulations on MATLAB/Simulink and experiments on a prototype 600-VA testbed with a TMS320LF28335 DSP. Finally, the comparative results for the proposed scheme and the conventional feedback linearization control scheme are presented to demonstrate that the proposed algorithm achieves an excellent performance such as fast transient response, small steady-state error, and low total harmonic distortion under load step change, unbalanced load, and nonlinear load with the parameter variations.</P>

Doubly fed induction generator wind turbines: A novel integrated protection circuit for low-voltage ride-through strategy

Justo, Jackson John,Mwasilu, Francis,Jung, Jin-Woo American Institute of Physics 2014 Journal of renewable and sustainable energy Vol.6 No.5

Doubly-fed induction generator based wind turbines: A comprehensive review of fault ride-through strategies

Justo, Jackson John,Mwasilu, Francis,Jung, Jin-Woo Elsevier 2015 RENEWABLE & SUSTAINABLE ENERGY REVIEWS Vol.45 No.-

<P><B>Abstract</B></P> <P>This paper presents an over-review of various strategies applied to enhance the fault ride-through (FRT) capability of the doubly-fed induction generators (DFIGs) based wind turbines (WTs) during transient-state. As the DFIG based WT system is sensitive to any grid disturbance, various FRT techniques based on: (i) installation of additional protection circuits, (ii) installation of reactive power injecting-devices and (iii) specific control approaches/structures have been proposed in the literature. Usually, the protection circuits or control structures are applied to limit the generated rotor over-current and undesirable dc-link over-voltage during grid disturbance. Meanwhile, the reactive power injecting-devices surpass any deficiency of the reactive power so as to improve the transient performance of the DFIG based WT and automatically bound the rotor current and the dc-link voltage. Actually, many research findings demonstrate an efficient protection of the DFIG without jeopardizing its operating strategy during transient-state. Therefore, this study focuses on emphasizing the present status of the rotor over-current and dc-link over-voltage protection solutions e.g. the crowbar and its related protection circuits, the reactive power injecting-devices such as the static synchronous compensators (STATCOM) and dynamic voltage restorer (DVR). Moreover, some control (modified) approaches/structures for limiting the inrush rotor currents which are based on linear and nonlinear control strategies are presented. Following the description of the overall system characteristics under steady-state and transient-state in the <I>d–q</I> axis, various protection strategies are extensively discussed to reveal their role to improve the FRT. Then, typical case studies are presented to demonstrate and support the reviewed FRT schemes. In that case, using the simulation results from the MATLAB/Simulink software the effectiveness of each case study during network faults are analyzed and compared.</P>

Online Parameter Identification for Model-Based Sensorless Control of Interior Permanent Magnet Synchronous Machine

Rafaq, Muhammad Saad,Mwasilu, Francis,Kim, Jinuk,Choi, Han Ho,Jung, Jin-Woo Institute of Electrical and Electronics Engineers 2017 IEEE transactions on power electronics Vol. No.

<P>This paper proposes an online identification method that can accurately estimate the stator resistance and dq-axis stator inductances for the effective model-based sensorless control of interior permanent magnet synchronous motors (IPMSMs). The proposed affine projection algorithms are uniquely designed in the estimated rotating gamma-delta frame to precisely identify the parameters mentioned above. The two time-scale approaches are employed in the affine projection algorithms to estimate the three electrical parameters. Despite the electrical parameter variations due to the temperature change andmagnetic saturation during operation, the rich enough data are provided to the affine projection algorithms in the discrete-time domain to accurately retrieve the updated parameters. These correctly estimated parameters are adapted to the extended back electromotive force observer for the sensorless control of IPMSM drives. Hence, the adaptation of online updated parameters makes the observer stable and robust to parameter variations as compared to the conventional observer without updated parameters. The MATLAB/Simulink-based simulation results and experimental results via a prototype IPMSM test-bed having TMS320F28335 DSP are given to verify the accurate convergence of the estimated parameters, which results into a stable sensorless control system under various operating conditions.</P>

Design and Stability Analysis of a Fuzzy Adaptive SMC System for Three-Phase UPS Inverter

Naheem, Khawar,Choi, Young-Sik,Mwasilu, Francis,Choi, Han Ho,Jung, Jin-Woo The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.4

This paper proposes a combined fuzzy adaptive sliding-mode voltage controller (FASVC) for a three-phase UPS inverter. The proposed FASVC encapsulates two control terms: a fuzzy adaptive compensation control term, which solves the problem of parameter uncertainties, and a sliding-mode feedback control term, which stabilizes the error dynamics of the system. To extract precise load current information, the proposed method uses a conventional load current observer instead of current sensors. In addition, the stability of the proposed control scheme is fully guaranteed by using the Lyapunov stability theory. It is shown that the proposed FASVC can attain excellent voltage regulation features such as a fast dynamic response, low total harmonic distortion (THD), and a small steady-state error under sudden load disturbances, nonlinear loads, and unbalanced loads in the existence of the parameter uncertainties. Finally, experimental results are obtained from a prototype 1 kVA three-phase UPS inverter system via a TMS320F28335 DSP. A comparison of these results with those obtained from a conventional sliding-mode controller (SMC) confirms the superior transient and steady-state performances of the proposed control technique.

Design and Stability Analysis of a Fuzzy Adaptive SMC System for Three-Phase UPS Inverter

Khawar Naheem,Young-Sik Choi,Francis Mwasilu,Han Ho Choi,Jin-Woo Jung 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.4

This paper proposes a combined fuzzy adaptive sliding-mode voltage controller (FASVC) for a three-phase UPS inverter. The proposed FASVC encapsulates two control terms: a fuzzy adaptive compensation control term, which solves the problem of parameter uncertainties, and a sliding-mode feedback control term, which stabilizes the error dynamics of the system. To extract precise load current information, the proposed method uses a conventional load current observer instead of current sensors. In addition, the stability of the proposed control scheme is fully guaranteed by using the Lyapunov stability theory. It is shown that the proposed FASVC can attain excellent voltage regulation features such as a fast dynamic response, low total harmonic distortion (THD), and a small steady-state error under sudden load disturbances, nonlinear loads, and unbalanced loads in the existence of the parameter uncertainties. Finally, experimental results are obtained from a prototype 1 kVA three-phase UPS inverter system via a MS320F28335 DSP. A comparison of these results with those obtained from a conventional sliding-mode controller (SMC) confirms the superior transient and steady-state performances of the proposed control technique.