Showing papers by "Navid Reza Abjadi published in 2007"

A new adaptive Direct Torque Control (DTC) scheme based-on SVM for adjustable speed sensorless induction motor drive

Abstract: This paper describes a combination of Direct Torque Control (DTC) and Space Vector Modulation (SVM) for an adjustable speed sensorless induction motor (IM) drive. The motor drive is supplied by a two level FPGA-based SVPWM inverter. The inverter reference voltage is obtained based on input-output feedback linearization control, using the IM model in the stator d-q axes reference frame with stator current and flux vectors components as state variables. In addition, a conventional PI speed controller is employed to generate the reference torque signal. Moreover, a novel Lyapunov based nonlinear stator flux observer is developed which provides simultaneous estimation of the stator flux, rotor speed, and rotor and stator resistances. Finally, the effectiveness and validity of the proposed control approach is verified by computer simulation and experimental results.

Nonlinear Decoupled Control for a Six-Phase Series-Connected Two Induction Motor Drive Using the Sliding-Mode Technique

Abstract: In this paper a nonlinear decoupled control is designed for a series connected two six-phase squirrel induction motor (IM) drive which is supplied by a six-phase space vector pulse width modulation voltage source inverter (SVPWM VSI) By using a well known phase transposition in the series connection, the independent control of two machines can be realized completely The nonlinear controller is developed in a stationary (alpha, beta) reference frame with rotor fluxes (lambdaalphatau, lambdabetatau) and stator currents (ialphas, ibetas) as state variables At the first, an ideal feedback linearization control (IFLC) system is adopted in order to decouple the torque and rotor flux amplitude of each IM Then to enhance the performance of the drive system against uncertainties of the plant, such as electrical and mechanical parameter variation, external torque disturbance and unmodelled system dynamics, a sliding- mode feedback linearization control (SMFLC) system is applied, that comprises a SM flux controller and a SM speed controller Moreover a two level SVPWM is used to supply the two motors drive system Finally, the effectiveness and capability of the proposed control strategy is verified by computer simulation