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Maximum Torque per Ampere Control of Induction Motor Drive without Mechanical Sensor
J.Soltani,M.Hajian,G.R.Arab 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
In this paper, the direct rotor flux field orientation control of speed sensorless induction motor (IM) is presented. In proposed control scheme, the maximum torque per ampere (MTPA) control strategy is achieved using a so-called fast flux search method. Based on this method, for a given load torque and rotor speed, the magnitude of rotor reference flux is adjusted step by step until the effective value (RMS) of stator current becomes minimized finally. In addition, using the IM fifth order model in the stationary reference frame, a nonlinear rotor flux observer is developed which is capable of motor resistances and rotor speed simultaneously estimation. Moreover, a useful method is introduced for DC offset compensation which is a major problem of AC drives especially at low speeds. Simulation and experimental results are presented to confirm the effectiveness of the proposed method.
J.Soltani,M.Ghassemi,G. Reza Arab Markadeh 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper describes a sliding-mode(SM) torque control for an interior type Permanent synchronous motor (IPMSM) based on space vector modulation (SVM).The motor drive is supplied by a two-level SV-based PWM inverter, so that the inverter reference voltage is generated by two integral types sliding mode(SM) controllers in a stationary two axes reference frame. In addition, the rotor speed and rotor position are on-line estimated by a sliding-mode observer, which uses only the stator currents and voltages. The observer stability is proved by Lyapunov theory. The control strategies of maximum torque per ampere (MTPA) related to IPMSM, in<br/> constant torque region and the flux weakening operation in constant power region are considered. Computer simulation results obtained, well demonstrate the effectiveness of the proposed control approach.
Characterisation of forests with trivial game domination numbers
Nadjafi-Arani, M. J.,Siggers, M.,Soltani, H. Springer Science + Business Media 2016 Journal of combinatorial optimization Vol.32 No.3
<P>In the domination game, two players, the Dominator and Staller, take turns adding vertices of a fixed graph to a set, at each turn increasing the number of vertices dominated by the set, until the final set dominates the whole graph. The Dominator plays to minimise the size of the set while the Staller plays to maximise it. A graph is -trivial if when the Dominator plays first and both players play optimally, the set is a minimum dominating set of the graph. A graph is -trivial if the same is true when the Staller plays first. We consider the problem of characterising -trivial and -trivial graphs. We give complete characterisations of -trivial forests and of -trivial forests. We also show that -connected -trivial graphs cannot have large girth, and conjecture that the same holds without the connectivity condition.</P>
Mehdi Mohammad Jafari,J. Soltani 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
Stability is the most important issue of power systems, because once the stability of large power systems is devastated, it can result in power collapse in one or several large areas, which may cause great loss in economy and great damage to the residents. This paper presents an approach, based on the use of the nonlinear system model and application of the feedback input-output linearization method, to improve dynamic stable of a two machine power system network using the unified power flow controller (UPFC), Meanwhile for synchronize machine modeling is used from 6<SUP>th</SUP> order model.
G. R. Arab Markadeh,J. Soltani 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
A Direct torque and flux control design for a sensorless induction motor, following a sliding mode observer is presented. In this control scheme, the torque error signal and the reference amplitude of the stator flux vector are delivered to a PI predictive controller. The predictive controller also uses information on the amplitude and position of the actual stator flux vector and measured current to determine the voltage command vector for space<br/> vector modulation (SVM). Using the fifth order model of three-phase induction machines in a stationary two axes reference frame, a sliding- mode (SM) observer is developed based on equivalent control concept in order to estimate the rotor speed and rotor time constant simultaneously. The stability of SM observer is proved by Lyapunov theory. In addition, a simple Lyapunov-based estimator is also used for on-line detecting of the stator resistance. Moreover, a composite SM controller is employed that combines nominal linear quadratic feedback control (LQC) and a SM contyrol. The composite speed controller, makes the drive system states follow the nominal trajectories in spite of parameter uncertainties and external load torque disturbance. The effectiveness of the proposed control scheme is verified by computer simulation.