This paper deals with the stability analysis of MRAS current speed estimator in a motoring and regenerating mode. The unstable operating points of the estimator, mainly in a regenerating mode are widely discussed. The expanded version of the estimator MRASCC is proposed to provide its stability in the whole operating range. The new correction coefficients for two analyzed stabilization methods are proposed. Finally, simulation results confirming the theoretical analysis are presented
The article is a summary of previous work on the possibility of using Petri layers in adaptive neuro-fuzzy controllers. In the first part of the paper the controller and two types of Petri layer have been presented, competitive layer which resets certain signals and transition layer which causes omission of signals. Layer properties were described and comparison has been made. In the second part of the paper, the results of a simulation showing the advantages and disadvantages of proposed solutions have been presented. Both quality of reference signal tracking and energetic cost of control process have been calculated. In the last part, analysis and comments on the results were made. Main conclusions are that transition Petri layer can significantly reduce growth of numerical cost of the algorithm despite the increase of fuzzy rules count. Also both competitive Petri layer and transition Petri layer by changing some inner signals can affect output value of the fuzzy system and thus the control quality indicators change. Most positive solutions have been pointed out.
In the paper, an analysis is made of the stator current sensor fault detector based on artificial neural network for vector controlled induction motor drive system. The systems with different learning algorithms and structures are analyzed and tested in different drive conditions. Simulation results are ob-tained in direct torque control algorithm (DTC-SVM) and performed in MATLAB/SimPowerSystem software.
The article presents an analytical description of the turn-off process of the power MOSFET suitable for use in high-frequency converters. The purpose of this description is to explain the dynamic phenomena occurring inside the transistor and contributing to the switching power losses. The detailed description uses the results of simulation studies carried out using a very precise model of the CoolMOS transistor manufactured by Infineon (IPW60R070C6). The theoretical analysis has been verified in experimental measurements of power dissipated during turn-off transient of MOSFET operating in a full bridge converter with switching frequency of 100 kHz. To estimate these switching losses an original thermovision method based on the measurement of heat dissipated in the power semiconductor switches has been used. The obtained results confirm the correctness of the conclusions drawn from the theoretical analysis presented in this paper.
The paper presents a Direct Field-Oriented Control (DFOC) of six-phase induction motor with Fuzzy-Logic speed controller. Mathematical models of the six-phase squirrel-cage induction motor and the six-phase voltage source inverter have been presented. A method of space vector modulation used to control a six-phase voltage source inverter has been described. Simulation studies of the DFOC with Fuzzy-Logic speed controller have been carried out and the results presented and discussed.
This paper presents predictive speed control of induction motor. The structure with finite control set and long prediction horizon is proposed. In methods with finite set of solutions there is assumed the use of signals that can be obtained in inverter only. Long prediction horizons allow better performance of predictive control structures to be achieved. In this case, long prediction horizon refers to systems with more than one prediction step. The weighting factors determine the properties of control structure via an optimization method using genetic algorithms. The results of simulation studies has been presented.
The article presents the current state and development trends of electrical drives, with particular emphasis on modern control structures and safety systems of various types of electrical machines. Special attention was paid to the needs of industrial drive systems and a possibility of practical implementation of complex control algorithms. Development perspectives of electrical drives are discussed from the perspective of new trends in control, power electronics and electrical machines, with consideration given to systems robust to faults of drive system elements.
The paper presents conclusions which are results of research on the use of high-speed drives operating in household appliances. The solutions that use three-phase or two-phase induction motors were taken into consideration. The assumed power of motors was up to 1 kW. The article describes the control process of power converters that is characterized by unity power factor and output voltages with the fundamental frequency up to 667 Hz. The requirements for control process were characterized and intelligent solutions were analysed, taking into account power outages, fluctuations, or accidental failures of supply voltage. The control functions of the controller elaborated, such as current and speed control, drive start-up and control circuit supply were described.
The article presents control strategy for the operation of a variable-speed wind energy conversion system with permanent magnet synchronous generator (PMSG). The electrical system of wind turbine consists of PMSG, Switch Mode Rectifier (SMR) and Grid Side Converter (GSC). The SMR converter is composed of an uncontrolled diode bridge and a DC/DC boost converter. In the control of the DC/DC boost converter the algorithm of Maximum Power Point Tracking (MPPT) has been applied. The MPPT algorithm allows the wind turbine to operate at maximum value of power coefficient in a wide range of wind speed. In the control of Grid Side Converter a method of Voltage Oriented Control (VOC) has been applied. High efficiency and accuracy of this control system were confirmed by simulation studies.
Adam Gozdowiak, Piotr Kisielewski and Ludwik Antal
The present paper shows the simulation results of turbogenerator faulty synchronization with inverse phase sequence. Great emphasis is placed on the physical phenomena existing in the rotor because the measurement of rotor damper bar currents is difficult in practice. There are presented the comparisons of maximum magnitudes of stator current and electromagnetic torque determined during faulty synchronization with maximum magnitudes designated during sudden short circuit after both no-load and rated operation condition. In addition, the effect of synchronizing limits on faulty synchronization is presented.