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Nga Thi-Thuy Vu,Dong-Young Yu,Han Ho Choi,Jin-Woo Jung IEEE 2013 IEEE transactions on industrial electronics Vol.60 No.10
<P>This paper presents a new sliding-mode control (SMC) scheme based on Takagi-Sugeno (T-S) fuzzy model for surface-mounted permanent-magnet synchronous motors (SPMSMs). First, a global T-S fuzzy model is given to represent the nonlinear dynamics of the SPMSM. The proposed T-S fuzzy-model-based sliding-mode controller considers motor parameter uncertainties and unknown external noises, so it is robust against motor parameter and load torque variations. Also, the linear matrix inequalities with feasible performance constraints are used to design both the sliding surface and the sliding-mode controller, and the stability of the proposed controller is analytically proven. In this paper, a simple sliding-mode observer is used to estimate load torque information. The proposed observer-based control scheme is implemented by using a Matlab/Simulink simulation tool and a prototype SPMSM drive with a TMS320F28335 DSP. Finally, simulations and experiments have been performed to justify that the proposed observer-based control strategy can guarantee a better performance (i.e., faster dynamic response, less steady-state error, more robustness, etc.) than the conventional observer-based nonfuzzy SMC scheme when there exist motor parameter uncertainties and unknown external disturbances.</P>
Nonlinear Speed Control of PM Synchronous Motor with Extended Kalman Filter Observer
Nga Thi-Thuy Vu,Jin-Woo Jung 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.3
This paper proposes a nonlinear speed controller for a permanent magnet synchronous motor (PMSM). In this paper, the load torque is estimated by an extended Kalman filter (EKF) observer because the proposed controller needs its knowledge. To confirm the effectiveness of the proposed control scheme, simulations and experiments are performed under motor parameter variations with a prototype PMSM drive system.
Nonlinear Speed Control of PM Synchronous Motor with Extended Kalman Filter Observer
Vu, Nga Thi-Thuy,Jung, Jin-Woo The Korean Institute of IIIuminating and Electrica 2011 조명·전기설비학회논문지 Vol.25 No.3
This paper proposes a nonlinear speed controller for a permanent magnet synchronous motor (PMSM). In this paper, the load torque is estimated by an extended Kalman filter (EKF) observer because the proposed controller needs its knowledge. To confirm the effectiveness of the proposed control scheme, simulations and experiments are performed under motor parameter variations with a prototype PMSM drive system.
Neuro-Fuzzy Control of Interior Permanent Magnet Synchronous Motors
Dong Quang Dang,Nga Thi-Thuy Vu,Han Ho Choi,Jin-Woo Jung 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
This paper investigates a robust neuro-fuzzy control (NFC) method which can accurately follow the speed reference of an interior permanent magnet synchronous motor (IPMSM) in the existence of nonlinearities and system uncertainties. A neuro-fuzzy control term is proposed to estimate these nonlinear and uncertain factors, therefore, this difficulty is completely solved. To make the global stability analysis simple and systematic, the time derivative of the quadratic Lyapunov function is selected as the cost function to be minimized. Moreover, the design procedure of the online self-tuning algorithm is comparatively simplified to reduce a computational burden of the NFC. Next, a rotor angular acceleration is obtained through the disturbance observer. The proposed observer-based NFC strategy can achieve better control performance (i.e., less steady-state error, less sensitivity) than the feedback linearization control method even when there exist some uncertainties in the electrical and mechanical parameters. Finally, the validity of the proposed neuro-fuzzy speed controller is confirmed through simulation and experimental studies on a prototype IPMSM drive system with a TMS320F28335 DSP.
Dang, Dong Quang,Vu, Nga Thi-Thuy,Choi, Han Ho,Jung, Jin-Woo The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
This paper investigates a robust neuro-fuzzy control (NFC) method which can accurately follow the speed reference of an interior permanent magnet synchronous motor (IPMSM) in the existence of nonlinearities and system uncertainties. A neuro-fuzzy control term is proposed to estimate these nonlinear and uncertain factors, therefore, this difficulty is completely solved. To make the global stability analysis simple and systematic, the time derivative of the quadratic Lyapunov function is selected as the cost function to be minimized. Moreover, the design procedure of the online self-tuning algorithm is comparatively simplified to reduce a computational burden of the NFC. Next, a rotor angular acceleration is obtained through the disturbance observer. The proposed observer-based NFC strategy can achieve better control performance (i.e., less steady-state error, less sensitivity) than the feedback linearization control method even when there exist some uncertainties in the electrical and mechanical parameters. Finally, the validity of the proposed neuro-fuzzy speed controller is confirmed through simulation and experimental studies on a prototype IPMSM drive system with a TMS320F28335 DSP.
Tracking the establishment of local endemic populations of an emergent enteric pathogen
Holt, Kathryn E.,Thieu Nga, Tran Vu,Thanh, Duy Pham,Vinh, Ha,Kim, Dong Wook,Vu Tra, My Phan,Campbell, James I.,Hoang, Nguyen Van Minh,Vinh, Nguyen Thanh,Minh, Pham Van,Thuy, Cao Thu,Nga, Tran Thi Thu National Academy of Sciences 2013 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.110 No.43
<P><I>Shigella sonnei</I> is a human-adapted pathogen that is emerging globally as the dominant agent of bacterial dysentery. To investigate local establishment, we sequenced the genomes of 263 Vietnamese <I>S. sonnei</I> isolated over 15 y. Our data show that <I>S. sonnei</I> was introduced into Vietnam in the 1980s and has undergone localized clonal expansion, punctuated by genomic fixation events through periodic selective sweeps. We uncover geographical spread, spatially restricted frontier populations, and convergent evolution through local gene pool sampling. This work provides a unique, high-resolution insight into the microevolution of a pioneering human pathogen during its establishment in a new host population.</P>
Nam Hai Trinh,Loc Ong Xuan,Nga Thi-Thuy Vu,Anh Tuan Nguyen 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.6
This paper proposes a model-free output feedback control-based adaptive fuzzy controller using a current-sensorless configuration for LC-filtered three-phase voltage source inverters (VSIs). The proposed adaptive fuzzy scheme is constructed of three parts: an adapter, an adaptive optimal fuzzy controller, and an adaptive optimal fuzzy identifier. The adapter is designed based on an adaptive neuro-fuzzy inference system (ANFIS) network which uses the error between the system output and identifier output as an input to generate the online updated parameters. Next, both the adaptive fuzzy controller and the fuzzy identifier are designed based on the Takagi-Sugeno (T-S) fuzzy model. In particular, the proposed algorithm is robust against external disturbance and parameter uncertainties due to not requiring the system parameters. Moreover, the proposed scheme uses a current-sensorless configuration, which reduces the system complexity and cost. Both the stability of the proposed method and the convergence of adapted parameters are completely assured by using the Lyapunov stability theory. Finally, the effectiveness of the proposed adaptive fuzzy controller is verified through simulation in comparison with a conventional T-S fuzzy controller. The results show that the proposed model-free output feedback control-based adaptive fuzzy controller yields better control performance, such as faster transient response, smaller steady-state error, and lower total harmonic distortion (THD) under the change of load (step changes of linear load, unbalanced load, and nonlinear load), parameter variations, and input disturbances.
A Nonlinear Sliding Mode Controller for IPMSM Drives with an Adaptive Gain Tuning Rule
Jung, Jin-Woo,Dang, Dong Quang,Vu, Nga Thi-Thuy,Justo, Jackson John,Do, Ton Duc,Choi, Han Ho,Kim, Tae Heoung The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3
This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method.
A Nonlinear Sliding Mode Controller for IPMSM Drives with an Adaptive Gain Tuning Rule
Jin-Woo Jung,Dong Quang Dang,Nga Thi-Thuy Vu,Jackson John Justo,Ton Duc Do,Han Ho Choi,Tae Heoung Kim 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3
This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method.