Abstract-Thispaper proposes an adaptive proportionalintegralderivative (PID) speed control scheme for permanent magnet synchronous motor (PMSM) drives. The proposed controller consists of three control terms: a decoupling term, a PID term, and a supervisory term. The first control term is employed to compensate for the nonlinear factors, the second term is made to automatically adjust the control gains, and the third one is designed to guarantee the system stability. Different from the offline-tuning PID controllers, the proposed adaptive controller includes adaptive tuning laws to online adjust the control gains based on the gradient descent method. Thus, it can adaptively deal with any system parameter uncertainties in reality. The proposed scheme is not only simple and easy to implement, but also it guarantees an accurate and fast speed tracking. It is proven that the control system is asymptotically stable. To confirm the effectiveness of the proposed algorithm, the comparative experiments between the proposed adaptive PID controller and the conventional PID controller are performed on the PMSM drive. Finally, it is validated that the proposed design scheme accomplishes the superior control performance (faster transient response and smaller steady-state error) compared to the conventional PID method in the presence of parameter uncertainties.Index Terms-Adaptive control, parameter uncertainties, PID control, surface-mounted permanent magnet synchronous motor (SPMSM). I. INTRODUCTIONN recent years, the ac motors are extensively applied in home appliances as well as industrial applications such as electric vehicles, wind generation systems, industrial robots, air conditioners, washing machines, etc. There are two main categories of the ac motors: induction motors (IMs) and permanent magnet synchronous motors (PMSMs). Nowadays, the IMs are used in about 70% of industrial electric motors due The authors are with the Division of Electronics and Electrical Engineering, Dongguk University, Seoul 100-715, Korea (E-mail: tonducdo@dongguk.edu).to their simplicity, ruggedness, and low production costs [1]- [5]. Despite that, the PMSMs are gradually taking over the IMs owing to their high efficiency, low maintenance cost, and high power density. However, the PMSM system is not easy to control because it is a nonlinear multivariable system and its performance can be highly affected by parameters variations in the run time [6]- [9]. Therefore, researchers always desire to design a high-performance controller which has a simple algorithm, fast response, high accuracy, and robustness against the motor parameter and load torque variations.Traditionally, the proportional-integral-derivative (PID) controller is widely adopted to control the PMSM systems in industrial applications owing to its simplicity, clear functionality, and effectiveness [10]. However, a big problem of the traditional PID controller is its sensitivity to the system uncertainties. Thus, the control performance of the conventional PID method can be seriou...

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Abstract-This paper proposes an adaptive control method of three-phase inverter for standalone distributed generation systems (DGSs). The proposed voltage controller includes two control terms: an adaptive compensating term and a stabilizing term. The adaptive compensating control term is constructed to avoid directly calculating the time derivatives of state variables. Meanwhile, the stabilizing control term is designed to asymptotically stabilize the error dynamics of the system. Also, a fourth-order optimal load current observer is proposed to reduce the number of current sensors and enhance the system reliability and cost effectiveness. Stability of the proposed voltage controller and the proposed load current observer is fully proven by using Lyapunov theory. The proposed control system can establish good voltage regulation such as fast dynamic response, small steady state error, and low total harmonic distortion (THD) under sudden load change, unbalanced load, and nonlinear load. Finally, the validity of the proposed control strategy is verified through simulations and experiments on a prototype DGS testbed with a TMS320F28335 DSP. For a comparative study, the feedback linearization for multi-input and multi-output (FL-MIMO) control scheme is implemented and its results are presented in this paper.Index Terms-Adaptive control, distributed generation system (DGS), load current observer, standalone, three-phase inverter, voltage control. I. INTRODUCTIONDistributed generation systems (DGSs) using renewable energy sources (such as wind turbines, photovoltaic arrays, biomass, fuel cells, etc.) are gaining more and more attention in electric power industry to replace existing fossil fuels and reduce global warming gas emissions. Nowadays, the DGSs are extensively used in grid-connected applications, but they are more economical in a standalone operation in case of rural villages or remote islands because connecting to the grid may lead to higher cost [1]- [5].In standalone applications, the load-side inverter of the Manuscript received May 31, 2012; revised September 21, 2012; accepted for publication November 10, 2012. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2012R1A2A2A01045312).Copyright (c) 2012 IEEE. Personal use of this material is permitted. However, permission to use this material for any other purposes must be obtained from the IEEE by sending a request to pubs-permissions@ieee.org.The authors are with the Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 100-715, South Korea (email: jinwjung@dongguk.edu).DGS operates analogous to an uninterruptible power supply (UPS) for its local loads [6]. Control of standalone DGSs or UPSs is an attractive research area in recent years. In these applications, the regulation performance of inverter output voltage is evaluated in terms of transient response time, steady state error, and total harmonic distortion (THD). Furthermore, the quality of invert...

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