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Power Electronics, Drives and Energy Systems, 2006. PEDES '06. International Conference on

Date 12-15 Dec. 2006

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Displaying Results 1 - 25 of 212
  • A program for harmonic modeling of distribution network transformers and determination of loss in the transformers and the amount of decrease of their life

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    Harmonic modeling of power network transformers is dealt with. The input of the electromagnetic model, voltages and distorting currents and the output of this model are harmonic losses. By using the thermal model and the input of losses temperature distribution is obtained. By using the temperature distribution the amount of transformer's loss of life and the related cost are calculated. For thermal modeling of the transformer existing experimental formulas in the other papers that have been obtained by experimental results have been used. About the presented harmonic model for the transformer's equivalent circuit the following points have been considered: 1) considering the shell and the juxtaposition effect in the modeling of loss. 2) Modeling of the core's saturation effect by adding the current source which is dependant on the voltage. 3) The core's loss as a function of the frequency. 4) Adding leakage and stray capacitors in the model. View full abstract»

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  • Novel Integral Cycle Voltage Controller for Self Excited Induction Generators

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4288 KB) |  | HTML iconHTML  

    This paper presents the theory of a new VAr regulator used for voltage control of self excited induction generators (SEIG). In this approach the excitation capacitors of each phase are switched individually by IGBTs at the zero crossing of respective capacitor currents, thereby eliminating switching losses and harmonics and reducing component count. Simulation results using Matlab-Simulink are presented and compared with experimentally obtained results. The developed integral control scheme presented here overcomes all the shortcomings of existing control schemes and, in addition to being self-starting is also capable of handling capacitive loads, thus making its application in standby generators acceptable with associated reduction in unit costs. View full abstract»

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  • EMI Modeling and Simulation of High Voltage Planar Transformer

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4049 KB) |  | HTML iconHTML  

    High voltage planar transformer is a new kind of power component using in the special environment. The EMI issue of it acts as an important role in the analysis of product reliability. This paper firstly presents a prototype and a application of the transformer. Then through finite element analysis (FEA) simulation, gives the calculation results of field distributions and current density distributions of the planar transformer windings. The calculation area is divided into two regions, inside the magnetic core and outside the core. The models and simulation methods are of great values to the EMI analysis of the planar transformer. View full abstract»

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  • Graphical Estimation of Optimum Weights of Iron and Copper of a Transformer

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4384 KB) |  | HTML iconHTML  

    Transformer may be designed to make one of the following quantities as minimum, (i) total volume (ii) total weight (iii) total cost (iv) total losses. In general these requirements are contradictory and it is normally possible to satisfy only one of them in a transformer. However the conditions for all the above quantities end in terms of the ratio of weight of iron and copper. In particular, the ratio is unity for optimum weight design of a transformer. Once we obtain optimum weights, optimum requirement for other quantities can easily be estimated. The design equations are modified so as to have only two variables in the equation. Necessary objective function and constraint equations are formed with two variables. Graphical method is adopted and optimum values are estimated separately and simultaneously. A 5 kVA single phase core type distribution transformer is taken and the condition for optimum weight design is verified and analysed. View full abstract»

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  • Nonlinear Behavior of Self-excited Induction Generator Feeding an Inductive Load

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (797 KB) |  | HTML iconHTML  

    The nonlinear behavior of a self-excited, smooth air gap, cage induction generator feeding an inductive load is analyzed in this paper, allowing for the effects of machine saturation. The self autonomous system is shown to exhibit a transition from a periodic orbit to a quasi-periodic orbit through a Neimark bifurcation. View full abstract»

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  • Effects of Different Voltage Sags on Three-Phase Transformers

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    This paper studies the effects of different types of voltage sags on three-phase transformers by means of computer simulation. The study shows that sags can produce transformer saturation during voltage recovery process. The saturation produces transformer inrush current which might be harmful in some cases. The influences of sag parameters (initial point-on-wave, duration and depth) have been analyzed in this paper. The simulation results show that current peak has a periodical dependence on sag duration and a linear dependence on sag depth. The highest peak currents are obtained for specific initial point-on-wave when the transformer supplied by different types of voltage sag. View full abstract»

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  • Design and Transient Analysis of Cage Induction Motor Using Finite Element Methods

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5887 KB) |  | HTML iconHTML  

    During the past few decades, the numerical computation of magnetic fields has gradually become a standard in electrical machine design. Finite element method (FEM) has the advantage over previous design calculation procedures in that geometric variations and irregularities, saturation and eddy current effects can be modeled with a high degree of accuracy. Besides these advantages, the method does allow the designer to obtain a clearer understanding of the flux distribution in the machine and so indicates directly the corrective action to be taken if necessary. The paper describes a method for the design and transient analysis of induction motor using two-dimensional finite-elements. It relies on the decomposition of the rotor currents into harmonic distributions and the use of auxiliary circuit equations to take the time stepping into account. View full abstract»

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  • Methodology for Estimating Performance Characteristics of Three Phase Induction Motor Operating Direct-on-Line or with Six Pulse Inverter

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3965 KB) |  | HTML iconHTML  

    The paper presents a methodology to derive parameters of an equivalent circuit representation of a three phase induction motor from the catalogue data provided by the electric motor manufacturer. The performance of the motor in terms of torque, efficiency and power factor is then calculated from the equivalent circuit. The paper presents validity of methodology with results of analysis with data of a motor from a catalogue and its comparison with the results of manufacturer's tests in the laboratory. The paper then also attempts to further analyze motor performance if it is driven by a six pulse inverter. View full abstract»

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  • Design of Squirrel Cage Induction Motors for Traction Applications

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6928 KB) |  | HTML iconHTML  

    This paper highlights the design issues of high power induction motors for traction applications. The circuit modeling and analysis of an induction machine is carried out with the parameters calculated from physical dimensions. The modification of the parameters to incorporate the time harmonic effects of inverter PWM supply, flux and frequency variation effect during closed loop V/F control is investigated in detail. The design program of the machine is developed using MATLAB. View full abstract»

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  • Effect of Sequential Phase Energization on the Inrush Current of a Delta Connected Transformer

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3314 KB) |  | HTML iconHTML  

    Magnetizing inrush current in power transformer creates severe power quality problems. Energization of the transformer from the delta side of a delta-star transformer does not allow the control of neutral resistor at the time of switching the supply for reducing the inrush current. Controlled switching at peak value of the voltage may reduce inrush current in one winding of the transformer, but the line currents are not reduced. Delayed and controlled energization of the third phase may reduce inrush winding currents in two windings and only one line current is reduced, but the inrush currents in the other two lines become very high. Simulation studies of delta side energization of a delta-star transformer depict the results under various switching conditions. View full abstract»

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  • Accurate Performance Prediction of Three-Phase Induction Motor by FEM Using Separate Saturation Curves for Teeth and Yoke

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3336 KB) |  | HTML iconHTML  

    In this paper, the performance analyses of the three phase induction motors have been done by finite element method (FEM) using time harmonic and transient with motion solvers. If there is no saturation in the ferrous portion of the mutual-flux path, the flux wave in the motor approaches a sine-wave shape, but some amount of saturation always exists in a typical three phase induction motor that has the effect of reducing the peak value of the flux wave. To study this phenomena, initially, 60 Hz saturation curves were used for the teeth as well as core yoke and performance analyses of the 2 motors (5 hp 4 P, and 15 hp 4 P) were done by FEM and then in turn, separate AC saturation curves for the teeth and the core yoke derived from the normal DC saturation curve were used, and FEM analyses were done to calculate all the electrical parameters of the motors. In both the cases, computational results are compared with the tested results, and it has been found that the percentage error between computational and tested results is less in case of separate saturation curves for teeth and core yoke compared to the other case. View full abstract»

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  • Nonlinear Sliding-Mode Controller for Sensorless Speed control of DC servo Motor Using Adaptive Backstepping Observer

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB) |  | HTML iconHTML  

    In this paper, the robust nonlinear sliding-mode speed sensorless speed controller for a DC servo motor is proposed. Based on state-space model representing the speed and current dynamics, the nonlinear sliding mode control is designed to track a linear reference model. An observer based on adaptive backstepping approach is used to estimate speed and uncertain parameters. With the proposed speed controller, the controlled DC servo motor possesses the advantages of good transient performance and robustness for parameters deviations, and transient dynamics of DC servo motor can be regulated through the design of a linear reference model which has the desired dynamic behaviors for the drive system. Finally, simulation results are demonstrated to validate the proposed controller. View full abstract»

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  • Robust Speed Sensorless Control of Doubly-Fed Induction Machine Based on Input-Output Feedback Linearization Control Using a Sliding-Mode Observer

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (213 KB) |  | HTML iconHTML  

    In this paper a nonlinear controller is presented for doubly-fed induction machine (DFIM) drives. The nonlinear controller is designed based on input-output feedback linearization control technique, combined with sliding-mode observer. Using the fifth order model of induction machine in fixed stator d ,q axis reference frames with stator current and rotor flux components as state variables. The nonlinear controller can perfectly track the torque and flux reference signals inspite of stator and rotor resistance variations. In order to make the drive system capable of operating in the motoring and generating modes below and above synchronous speed, two level SVM-PWM back-to-back voltage source inverters are employed in the rotor circuit. Computer simulation results obtained, confirm the effectiveness and validity of the proposed control approach. View full abstract»

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  • Adaline Based Control of Solid State Voltage Regulator for Isolated Asynchronous Generators

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6800 KB) |  | HTML iconHTML  

    This paper deals with the adaline based control of a solid state voltage regulator (SSVR) for isolated asynchronous generator (IAG). With indirect current control, proposed control scheme uses a fast adaptive linear element (adaline) based neural network reference current extractor, which extracts the real positive sequence current component without any phase shift. The estimation of the reference current through adaline utilizes LMS (least means squire) algorithm to maintain online calculation of weights. A closed loop PI (proportional-integral) controller is used for regulating the DC bus of SSVR. The control scheme is verified for regulating the voltage of an isolated asynchronous generator in constant speed variable power application through simulation in MATLAB using Simulink and PSB (power system block) toolboxes. View full abstract»

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  • Development of a Prototype Controller for PMDC Motor Based Portable Telemetry Tracking System for Defense Application

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4846 KB) |  | HTML iconHTML  

    In the range, block house telemetry plays an important role in providing quick look telemetry data of the airborne vehicle, particularly for initial phase of the trajectory to the range experts for their decision-making and control. Presently blockhouse telemetry front-end helical antenna is manually steered at the blockhouse top. This is a concern of safety and does not give any guarantee of acquiring data due to the poor visibility when the airborne vehicle goes far off. The paper describes prototype model of portable tracking antenna system that facilitates the user to control antenna both in manual and auto mode remotely from the block house. An array of four helical antennas were used to generate the dc tracking error in both azimuth and elevation plane. It also explains a control mechanism by which antenna systems are steered in both azimuth as well as elevation plane using power transistors and permanent magnet direct current motors. This method uses AGC comparison, which is relatively simpler and economical than conventional single channel amplitude comparison mono pulse or electronic scanning tracking method. The prototype was developed, tested and successfully driven the antenna in both manual as well as auto mode for real time telemetry data acquisition for airborne vehicle at blockhouse. View full abstract»

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  • Design & Development of a High Performance Electronic Starter for Single - Phase Induction Motors

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4989 KB) |  | HTML iconHTML  

    Single phase induction motors are not self-starting unless they are started as quasi-two phase motors. This necessitates a starting winding, with or with out starting capacitors, which is switched out once motor is accelerated. A centrifugal gear having flying weights and a mechanical contact type switch is most commonly used to do this function. This paper describes a non-contact type; non-mechanical type, electronic switch that eliminates contact sparking and mechanical assembly criticality, thereby improving the reliability, motor life and servicing cost. The various types of electronic starters available in market operate on different principles like time delay or capacitor voltage or winding turns ratio or phase difference between start and run windings. The operation of the electronic starter, described in this paper, is based on actual shaft speed, similar to mechanical switch, but switching the capacitor/winding electronically. The starting capacitor and/or the winding is switched out based on the simple speed feed back data obtained. The switching instant is decided by a micro-processor based logic circuit using speed feedback and the switching is done using single/multiple semiconductor switches. Electronic starter reduces the inventory cost due to its flexibility. View full abstract»

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  • Transient Analysis of a Single-Phase Self-Excited Induction Generator using a Three-Phase Machine feeding Dynamic Load

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6589 KB) |  | HTML iconHTML  

    This paper presents the transient behavior of a single-phase self-excited induction generator (SEIG) supplying a dynamic load i.e. induction motor. The generator consists of a three-phase star connected induction machine with three capacitors and a single-phase induction motor load. The dynamic models of the SEIG and the motor load have been developed based on stationary reference frame d-q axes theory and the equations of excitation capacitors are described by three-phase abc model. Heavy transients occur during the switching of induction motor and the system becomes unstable. The use of damping resistors across series capacitors is proposed to damp out the transients for the stable operation. Using the damping resistors, the motor can be started up successfully. Simulated results have been compared with the experimental results for unsuccessful starting without damping resistances and successful starting with damping resistances to validate the developed model. View full abstract»

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  • Performance Analysis of a Three-Phase Squirrel-Cage Induction Motor under Unbalanced Sinusoidal and Balanced Non-Sinusoidal Supply Voltages

    Page(s): 1 - 4
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    As a result of the increasing use of electronic devices and other non-linear loads, the waveforms of the electricity supply voltage are being distorted and inequalities are appearing between the phases. This deterioration is associated with problems of electromagnetic incompatibility and reductions in the efficiency of loads such as motors. This paper investigates the negative effects of unbalanced sinusoidal voltage (0.96% unbalance and 2.9% THD) which always present in the power supply over balanced (inverter supply) non-sinusoidal voltage (23.7% THD) on the performance of induction motor in terms of line currents, power factor and efficiency. Under both supply conditions, the performance of a 5 HP three-phase squirrel cage induction motor was measured through a real load test. According to the test results and analysis, the negative effects of unbalanced sinusoidal voltage are more than the balanced non-sinusoidal voltage on the motor's performance. The financial losses caused by unbalanced voltage of the same motor are determined. View full abstract»

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  • Efficiency Optimization of Induction Motor Using a Fuzzy Logic Based Optimum Flux Search Controller

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    Induction motors are, without any doubt, the most used in industry. Motor drive efficiency optimization is important for two reasons: economic saving and reduction of environmental pollution. In this paper, advantages of using fuzzy logic in steady-state efficiency optimization for induction motor drives are described. Experimental results of a fuzzy logic based optimum flux search controller are presented. There are so many speed control techniques available, like scalar control, vector control, sensor less control etc. Due to coupling effect, the scalar control has inferior performance and vector control is a method of speed control in which both magnitude and phase angle of current can be controlled. In vector control, the presence of speed sensor at shaft decreases the reliability and ruggedness. For transient states, a new original idea is introduced: a fuzzy logic based controller, actuating as a supervisor, is proposed to work with reduced flux levels during transients to optimize efficiency also in dynamic mode. Two different rule tables are designed, for torque transitions and for reference speed changes. With this controller, efficiency can be improved in transients, and also search controller convergence speed is increased. In my work efficiency optimization of induction motor using fuzzy logic controller was carried out using Matlab. View full abstract»

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  • Observer Based Position and Speed Estimation of Interior Permanent Magnet Motor

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (251 KB) |  | HTML iconHTML  

    This paper presents position sensorless interior permanent magnet synchronous motor drive using a discretized extended kalman filter algorithm (EKF). An observer based speed estimator which can be used for the state estimation of a non linear dynamic system in real time is presented here. Speed and position estimation of IPM is simulated using MATLAB and results of step variation in speed, load perturbation and flux weakening are presented to substantiate the proposed estimation of the speed. View full abstract»

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  • Genetic Algorithm Based Optimal Design of Switching Circuit Parameters for a Switched Reluctance Motor Drive

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    In this paper, an optimization method based on genetic algorithms (GA) is applied to find the best design parameters of the switching power circuit for a switched reluctance motor (SRM). The optimal parameters are found by GA with two objective functions, i.e. efficiency and torque ripple. A fuzzy expert system for predicting the performance of a switched reluctance motor has been developed. The design vector consists of design parameters, and output performance variables are efficiency and torque ripple. An accurate analysis program based on improved magnetic equivalent circuit (IMEC) method has been used to generate the input-output data. These input-output data are used to produce the optimal fuzzy rules for predicting the performance of SRM. Table look-up scheme and gradient decent training are used for optimal fuzzy prediction designed. The results of the optimal switching power circuit design for a 8/6, four phase, 4 kW, 250 V, 1500 rpm SR motor. View full abstract»

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  • Reduction of Cogging Torque in PMBLDC Motor with Reduced Stator Tooth Width and Bifurcated Surface Area Using Finite Element Analysis

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    This paper proposes a method for reduction of cogging torque with reduced stator tooth width and bifurcated active surface area using finite element analysis. For the proposed changes in the motor design the variation in the flux density distribution in the air gap, cogging torque and reluctance torque ripple are determined. The variations in the torque developed by the motor, cogging torque, output power, losses and efficiency for different stator tooth shapes are recorded. From the present study it is observed that there is a significant reduction of cogging torque with reduced stator tooth width & bifurcated active surface area compared with a specified motor. View full abstract»

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  • A Novel Phasor Diagram of Interior Permanent Magnet Synchronous Motors based on Spiral Vector Theory

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    The paper presents a novel phasor diagram of interior permanent magnet synchronous (IPMS) motor for steady state analysis. Starting from first principle, the phase decoupled spiral vector model of the IPMS motor has been obtained. A phase decoupled voltage equation in phasor can be obtained from the spiral vector IPMS motor at steady state. In the phasor diagram, the effect of reluctance variation is represented as reluctance voltage. The shaft power output of the motor is the sum of power due to field voltage and reluctance voltage. The steady state performance of the IPMS motor can be predicted with the use of this phasor diagram. The novel phasor diagram can also be used for steady state performance analysis of salient pole synchronous and reluctance machine. View full abstract»

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  • A Novel DTC Strategy of Torque and Flux Control for Switched Reluctance Motor Drive

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4867 KB) |  | HTML iconHTML  

    In this paper, a novel methodology for control of torque and flux of switched reluctance motor (SRM) drive in a hystersis manner is described. The philosophy of control is the direct torque control (DTC) by analysis the non-uniform torque characteristics of the motor. The scheme directly controls the torque and the torque ripple by controlling the magnitude of flux linkage and change in speed of stator flux vectors. Further importance is given to overcome the difficulties of conventional linear and non-linear controls of SRM drives. This new technique can be implemented in real time with low cost microcontrollers and higher simplicity. View full abstract»

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  • Remedial Strategies for the Minimization of Cogging torque in PMBDC Motor possessing Material Saturation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3777 KB) |  | HTML iconHTML  

    This paper investigates the various strategies for the minimization of cogging torque produced in a permanent magnet brushless DC (PMBDC) motor for a low speed, speed stability stringent spacecraft application with cold coil redundancy. The effect of the material saturation on cogging torque is analyzed using both FE software simulation and hardware simulation. Based on the simulation, suitable method has been derived for the minimization of the cogging torque for this particular application and the machine is realized. Test results shows that a decrease of 90% of the cogging component with 20% of alignment component in the developed torque pattern once saturation is removed. View full abstract»

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