An electric power steering system (EPS) is a new type of steering system developed after a mechanical hydraulic power system (MHPS) and electric-hydraulic power steering system (EHPS). In order to coordinate and solve the portability and sensitivity of the steering system optimally, taking an induction power steering system as the research object, the control algorithm of induction motor control under the EPS is studied in this paper. In order to eliminate the feed-forward performance degradation caused by the change of feed-forward parameters, an on-line identification algorithm of feed-forward parameters is proposed. It can improve the control performance of online identification among three feed-forward parameters in the T-axle motor, it improves on the robustness of feed-forward control performance, at the same time it also gives simulation and test results. This method can improve the control performance of the three feed-forward parameter online identification of the T-axis motor and improve the robustness of feed-forward control performance. At the same time, simulation and test results are given. The simulation results show that the algorithm can significantly improve the response speed and control accuracy of EPS system control.
This paper deals with the modelling of traction linear induction motors (LIMs) for public transportation. The magnetic end effect inherent to these motors causes an asymmetry of their phase impedances. Thus, if the LIM is supplied from the three-phase symmetrical voltage, its phase currents become asymmetric. This effect must be taken into consideration when simulating the LIMs’ performance. Otherwise, when the motor phase currents are assumed to be symmetric in the simulation, the simulation results are in error. This paper investigates the LIM performance, considering the end-effect induced asymmetry of the phase currents, and presents a comparative study of the LIM performance characteristics in both the voltage and the current mode.
This paper investigates the application of a novel Model Predictive Control structure for the drive system with an induction motor. The proposed controller has a cascade-free structure that consists of a vector of electromagnetics (torque, flux) and mechanical (speed) states of the system. The long-horizon version of the MPC is investigated in the paper. In order to reduce the computational complexity of the algorithm, an explicit version is applied. The influence of different factors (length of the control and predictive horizon, values of weights) on the performance of the drive system is investigated. The effectiveness of the proposed approach is validated by some experimental tests.
The purpose of the paper is the investigation of possibility of utilization of a single-phase induction machine, designed and normally operating as a single-phase capacitor induction motor, as a self-excited single-phase induction generator, which can be used to generate electrical energy from non-conventional energy sources. The paper presents dq model of the self-excited single-phase induction generator for dynamic characteristics simulation and steady-state model based on double revolving field theory with two phase symmetrical components – a forward and backward revolving field for performance of the generator under resistive load. Excitation and load characteristics obtained by simulation showed considerable influence of method of capacitor configuration in the load stator winding on terminal voltage, current and output power of the generator under load. An specific construction of the stator windings together with capacitor requirements to obtain nominal output power at desired self-regulating terminal voltage over the operating range will be the aim of further research.
The paper recapitulates recently conducted investigations of non-proportional Luenberger observers, applied to reconstruction of state variables of induction motors. Three structures of non-proportional observers are analyzed, a proportional-integral observer, modified integral observer and observer with integrators. Criteria for gain selection of the observer are described, classical ones based on poles, as well as additional, increasing observer’s robustness. Fulfilment of the presented criteria can be ensured with the three proposed methods for gain selection, two analytical, based on dyadic transformation and one based on optimization.
In this paper, an analysis of the induction motor control scheme based on the Direct Rotor Flux Oriented Control (DRFOC) for a whole speed range, including fieldweakening (FW) regions is presented. Two field-weakening algorithms have been compared and verified through simulation with a 3.0 [kW] induction motor drive.
A new observer of induction motor state variables is proposed in the paper. A nonlinearity of the main magnetic path is expressed as a function of a properly chosen parameter versus the position vector length. The value of the mutual inductance received n the identification algorithm is calculated exploiting the estimated values of the state variables. The coefficients appearing in the differential equations of the observer system are modified in each step of the algorithm on the basis of the calculated mutual inductance. The analysis of convergence of the identification algorithm is shown in this paper.
In this paper a scaling approach for the solution of 2D FE models of electric machines is proposed. This allows a geometrical and stator and rotor resistance scaling as well as a rewinding of a squirrel cage induction machine enabling an efficient numerical optimization. The 2D FEM solutions of a reference machine are calculated by a model based hybrid numeric induction machine simulation approach. In contrast to already known scaling procedures for synchronous machines the FEM solutions of the induction machine are scaled in the stator-current-rotor-frequency-plane and then transformed to the torque- speed-map. This gives the possibility to use a new time scaling factor that is necessary to keep a constant field distribution. The scaling procedure is validated by the finite element method and used in a numerical optimization process for the sizing of an electric vehicle traction drive considering the gear ratio. The results show that the scaling procedure is very accurate, computational very efficient and suitable for the use in machine design optimization.
A fault diagnostics system of three-phase induction motors was implemented. The implemented system was based on acoustic signals of three-phase induction motors. A feature extraction step was performed using SMOFS-20-EXPANDED (shortened method of frequencies selection-20-Expanded). A classification step was performed using 3 classifiers: LDA (Linear Discriminant Analysis), NBC (Naive Bayes Classifier), CT (Classification Tree). An analysis was carried out for incipient states of three-phase induction motors measured under laboratory conditions. The author measured and analysed the following states of motors: healthy motor, motor with one faulty rotor bar, motor with two faulty rotor bars, motor with faulty ring of squirrel-cage. Measured and analysed states were caused by natural degradation of parts of the machine. The efficiency of recognition of the analysed states was good. The proposed method of fault diagnostics can find application in protection of three-phase induction motors.
The paper describes high output induction motors driving large applications of heavy starting conditions. Heavy start is characterised by long accelerating time and occures in drives of hudge inertia torque, esspecially when performed at full load. The reliable operation of the motors depends on proper design and quality of rotor's cage. The aspects of thermal behaviour and electrodynamic forces have to be considered during the design of the motor for hard working conditions. In the paper the rotor with idle bars is investigated.
The efficiency of the solid-rotor induction machines depends on axial length of rotor (including the end-regions). Determination of the best axial length is problematic because of current density distribution in the end-regions and also because of absence of dedicated methods and models. This work proposes a method that circumvents this difficulty. It is based on the numerical determination of a dimensionless rotor-end factor using a combination of three- and two-dimensional finite element models restricted to the motor rotor. Such the end factor can be used in both analytical and numerical model of the machine in order to determine the typical performance characteristics. In this work, using this method, we determined an optimal length of the slitted solid rotor of a motor operating at 12 000 rpm, that maximizes the motor efficiency. The results of computations and measurements, carried out on the laboratory test-stand, are presented.
This paper describes a fault-tolerant controller (FTC) of induction motor (IM) with inter-turn short circuit in stator phase winding. The fault-tolerant controller is based on the indirect rotor field oriented control (IRFOC) and an observer to estimate the motor states, the amount of turns involved in short circuit and the current in the short circuit. The proposed fault controller switches between the control of the two components of measured stator current in the synchronously rotating reference frame and the control of the two components of estimated current in the case of faulty condition when the estimated current in the short circuit is not destructive of motor winding. This technique is used to eliminate the speed and the rotor flux harmonics and to assure the decoupling between the rotor flux and torque controls. The results of the simulation for controlling the speed and rotor flux of the IM demonstrate the applicability of the proposed FTC.
The article introduced some expressions for self- and mutual slot leakage inductance of phase windings for the mathematical model of an induction machine in the natural phase coordinate system and for dq0 model and in an arbitrary coordinate frame. Calculation of self- and mutual slot leakage inductance have been performed for threephase double-layer, delta and delta-modified winding connections. Introduced expressions may be useful in the design of windings and in the analysis of dynamic states of AC electrical machines.
In this paper a comparison of numerically determined and measured electromagnetically exited noise of an induction motor is presented. The calculations are accomplished using FEM for an example motor, which is a 290 kW inverter-fed asynchronous machine. The approach starts with the electromagnetic and mechanical consideration. The focus is set on acoustic considerations, which contain the 3D-FE-model and measurement setup in the sound chamber.
The electrical power drawn by an induction motor is distorted in case of appearance of a certain type of failures. Under spectral analysis of the instantaneous power one obtains the components which are connected with definite types of damage. An analysis of the amplitudes and frequencies of the components allows to recognize the type of fault. The paper presents a metrological analysis of the measurement system used for diagnosis of induction motor bearings, based on the analysis of the instantaneous power. This system was implemented as a set of devices with dedicated software installed on a PC. A number of measurements for uncertainty estimation was carried out. The results of the measurements are presented in the paper. The results of the aforementioned analysis helped to determine the measurement uncertainty which can be expected during bearing diagnostic measurements, by the method relying on measurement and analysis of the instantaneous power of an induction machine.
Among all control methods for induction motor drives, Direct Torque Control (DTC) seems to be particularly interesting being independent of machine rotor parameters and requiring no speed or position sensors. The DTC scheme is characterized by the absence of PI regulators, coordinate transformations, current regulators and PWM signals generators. In spite of its simplicity, DTC allows a good torque control in steady state and transient operating conditions to be obtained. However, the presence of hysteresis controllers for flux and torque could determine torque and current ripple and variable switching frequency operation for the voltage source inverter. This paper is aimed to analyze DTC principles, the strategies and the problems related to its implementation and the possible improvements.
Conventional field-orientated Induction motor drives operate at rated flux even at low load. To improve the efficiency of the existing motor it is important to regulate the flux of the motor in the desired operating range. In this paper a loss model controller (LMC) based on the real coded genetic algorithm is proposed, it has the straightforward goal of maximizing the efficiency for each given load torque. In order to give more accuracy to the motor model and the LMC a series model of the motor which consider the iron losses as a resistance connected in series with the mutual inductance is considered. Digital computer simulation demonstrates the effectiveness of the proposed algorithm and also simulation results have confirmed that this algorithm yields the optimal efficiency.
Design of a delta/polygon-connected autotransformer based 36-pulse ac-dc converter is presented in this paper. The 36-pulse topology is obtained via two paralleled eighteen-pulse ac-dc converters each of them consisting of a nine-phase (nine-leg) diode bridge rectifier. For independent operation of paralleled diode-bridge rectifiers, two interphase transformers (IPT) is designed and implemented. A transformer is designed to supply the rectifier. The design procedure of magnetics is in a way such that makes it suitable for retrofit applications where a six-pulse diode bridge rectifier is being utilized. The proposed structure has been implemented and simulated using Matlab/Simulink software under different load conditions. Simulation results confirmed the significant improvement of the power quality indices (consistent with the IEEE-519 standard requirements) at the point of common coupling. Furthermore, near unity power factor is obtained for a wide range of DTCIMD operation. A comparison is made between 6-pulse and proposed converters from view point of power quality indices. Results show that input current total harmonic distortion (THD) is less than 4% for the proposed topology at variable loads.
The paper presents the mathematical models of dual stator squirrel-cage induction motor, formulated in phase coordinate system and in general transformed space vector form. The two types of models of dual stator induction motor are considered. The control systems of field-oriented control (IFOC and DFOC) and direct torque control (DTC) of the dual stator induction motor have been described and discussed.
Maximum Torque Control (MTC) is a new method applied for control of induction motor drives. The drive is controlled by dc voltage supplying a converter in the range below nominal speed and by a field that weakens for a speed range above the nominal speed. As a consequence, the control is quite similar to the control of a classical separately excited dc motor. This control method could be explained as a kind of sim- plification of Direct Torque Control (DTC), because the switching scheme is the same as for the DTC, but the variable responsible for a torque control is constantly set for “torque increase”. This kind of control of induction motor drive is simpler than DTC because torque values need not be estimated. The proposed control method offers very good performance for 3-phase induction motors and requires smaller switching frequency in comparison to DTC and Field Oriented Control (FOC). The application of the con- trol is widely demonstrated for a 3-phase 315 kW, 6 kV motor drive by use of computer simulation.