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This paper presents a speed-sensorless control algorithm for induction motors, based on the stator flux-oriented control. The algorithm has the advantage of insensitivity to rotor parameters and load varying, stator flux and rotor speed is closed loop controlled respectively. The main improvement is that stator flux is estimated based on a modified integrator which is developed to solve the problems...
This paper will describe how finite element analysis can be utilize to design and model the performance of rotary electrical machines. Special interest placed on the induction motor since the design is simple, and has greatest influence in operation of electrical power system. Transient AC analysis has been studied as it is necessary to examine the motor's performance dynamically. Opera 2D software...
This paper presents a new method of on-line estimation for the stator and rotor resistances of the induction motor in the indirect vector controlled drive, using artificial neural networks. The back propagation algorithm is used for training of the neural networks. The error between the rotor flux linkages based on a neural network model and a voltage model is back propagated to adjust the weights...
The doubly-fed induction generator (DFIG) based wind turbines of today are often equipped with a crowbar, which can be used to limit the inrush rotor current and protect the ac excitation converter from damage via a set of resistors that are connected to the rotor windings of the DFIG. When the rotor current becomes too high due to the severe grid voltage dips on the transmission line, the crowbar...
The paper detail analyzes the relationship between position phase error and free-wheel current of inactive phase. It is found that free-wheel current error can exactly reflect position phase error, and a novel closed loop control method to correct position phase is proposed. In order to keep free-wheel current of the inactive phase symmetrical, free-wheel current error is inputted to PI controller,...
This paper propose a control project using adaptive feedback linearization on the AC servo system. Theory derivation and computer simulation proved that the project can implement robust control of parameters and has the actual application value.
Dual EKF which is suitable for simultaneously on-line estimating states and parameters of nonlinear systems is applied to the rotor resistance and rotor flux on-line simultaneous estimation problem of vector control system of induction machines. Based on dual EKF, a self-tuning vector control system with higher performances is established. Simulation results show that the proposed scheme is effective...
A new approach employing the circuit analysis theory instead of electromagnetic field theory is presented to calculate the rotor resistances and inductances of single-phase induction motors. The resistance and inductance parameters are obtained at positive sequence and negative sequence frequencies, respectively, with skin effect consideration. The rotor bar is divided into many thin-layers with their...
The skin effect of rotor current is one of key factors which affect the simulation accuracy of three-phase induction motors with deep rotor bars. This paper proposes an improved dynamic model considering the skin effect of three-phase induction motors at arbitrary operation, from the starting to rated-load operation. The simulation results using the proposed model are compared with those from the...
In this paper, a rotor flux observer in the stator current vector orientation synchronous reference frame (DQ reference frame) is introduced and analyzed first. Then indirect vector control is combined with the DQ rotor flux observer, and a slip frequency correction method is proposed to achieve flux and torque decoupling control. Basic principles and system schematic diagram are described. Simulations...
This paper evaluates the advantages of using the slip-based thermal model with data collected from an actual field installation. The paper presents information on motor starts before and after installation of the new motor protection technology. Improvement claims are based on the first order thermal model, enhanced with the calculation of slip and rotor resistance to improve accuracy of its starting...
There are applications where low current inrush and or high starting torque are specified for reducing disturbance on the electrical distribution network. There are also situations where it is required to successfully start large AC motors at reduced voltage conditions when only one substation transformer of a double-ended transformer is in service at petrochemical plants. The latter condition requires...
Thermal models are often used in motor overload protection relays to predict rotor temperature. Under impaired cooling conditions, the parameters in the thermal models need to be tuned accordingly to reflect changes in the motor cooling capability. The tuning process requires accurate rotor temperature as a reference signal. This reference signal is estimated from the rotor resistance based on the...
The authors develop the squirrel cage induction machine model for the diagnosis of defects from an approach of magnetically coupled multiple circuits. The generalized model is established on the base of mathematical recurrences. The winding function theory is used for determining the rotor resistances and the inductances in the case of n-broken bars and broken end-ring. Simulation results, in Part...
Bearingless induction motors have combined characteristics of an induction motor and magnetic bearings. Bearingless induction motors tend to suffer from the influence of rotor resistance variation under field-oriented control. Several rotor resistance identification methods have been proposed in the literature. In this paper, a novel rotor resistance identification technique based on variables in...
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