| EPE 2007 - Subtopic 11-3 - DS: Adjustable speed drives |
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 | A comparison of SPSA method and compact genetic algorithm for the optimization of induction motor position control
By MININNO Ernesto; SALVATORE Luigi; CUPERTINO Francesco; NASO David | [View]
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Abstract: This paper describes the implementation of self-optimizing embedded control schemes for induction motor drives. The online design problem is formulated as a search problem and solved with stochastic optimization algorithms. The objective function takes into account the tracking error, and is directly measured on the hardware bench. In particular, we compare two efficient optimization algorithms, a Simultaneous Perturbation Stochastic Approximation method, and a Compact Genetic Algorithm. Both search strategies have very small computational requirements, and therefore can be directly implemented on the same processor running the control algorithm.
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| | A network model for inverter-fed induction-motor drives
By WEILAND Thomas; HENZE Olaf; ROCKS Alexander; DE GERSEM Herbert; BINDER Andreas; HINRICHSEN Volker | [View]
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Abstract: A network model is presented for inverter-fed induction motors operated at steady state. The model is based on the transmission line matrix (TLM) method considering the cable impedance L, capacitance C, conductivity G and resistance R described by 3x3 matrices combined with a 3 phase (abc)-model for the induction machine. For steady-state operation, the induction-motor model is reduced to a 3x3 frequency-dependent matrix which can be described in a very simple way. The 3-phase cable is modelled using the Transmission-Line (TLM) Theory where cable impedance L, capacitance C, conductivity G and resistance R are described by 3x3 matrices. The induction-motor is represented by a 3-phase (abc)-approach. In the steady state case this approach is simplified to a 3x3 impedance matrix which can be coupled with the TLM-model. The result is a transfer function which couples the input voltage with the output voltage at the motor. To calculate the voltage at the motor, the voltages pulses from the inverter are transformed into the frequency domain via FFT. In the frequency domain the voltage at the motor is easy computed by multiplication with the transfer function. The simulation results are compared to measurements for the voltage output of a drive with an inverter, cable and induction motor for which the parameters are well known.
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| | A self-commissioning method for permanent magnet dc-motor drives
By SEEBACHER Roland R.; DANNERER Guenther; KRISCHAN Klaus | [View]
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Abstract: The conventional model describing the electrical and mechanical properties of a permanent magnet dc-motor drive is extended in order to take into account the oscillations of the induced voltage that are caused by slotting effects, and - as the electrical machine investigated is fed from a pwm-inverter - in order to include the inverter's voltage drop. Furthermore, a method is proposed to estimate the extended model's parameters from one single experiment that is easy to be carried out. The method is based on recording the inverter's dc-link voltage, the dc-motor's armature current and the rotor's angular position as a function of time while the dc-motor is fed from the inverter. As the inverter is controlled by a digital signal processor system, this can be done without using additional measuring devices, but just with the dsp-system's measurement facility which is required anyway for the controlled operation of the drive. No additional mechanical components have to be coupled if the motor is equipped with an incremental encoder. Besides the method's aptitude for self commissioning purposes, it is also perfectly suited for quality control as in addition to the relevant electrical parameters one can also estimate mechanical parameters (e.g. to describe the load torque). This makes it easy to control the assembly quality of the motor. Last but not least the model's predictions are compared to experimental results and this comparison clearly shows the benefits of the method proposed.
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| | A Simple Design Method Based on Vector Control of AC Machines with LC Filter
By SAITO Ryosuke; KUBOTA Hisao | [View]
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Abstract: This paper presents a simple voltage control system of AC machines using PWM voltage source inverter with output LC filters. By assuming a motor as a current source, the voltage is controlled by a simple proportional differential (PD) control. The vector control and PD control can be separately controlled in this system. A method for disturbance rejection is also described. The effectiveness of the proposed method is verified by simulations and experiments.
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| | A two-motor centre-driven winder drive fed by a five-leg voltage source inverter
By JONES Martin; JEFTENIC Borislav; DUJIC Drazen; BEBIC Milan; LEVI Emil | [View]
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Abstract: Recent research has shown that it is possible to independently control two three-phase induction machines while supplying them via a single five-leg voltage source inverter (VSI). In such a two-motor drive system one phase of each motor is connected to a common inverter leg. Major shortcoming of this topology for general-purpose applications is the need to double the DC bus voltage in order to achieve the same speed control range as with the standard dual three-phase VSI topology. Also, the semi-conductors of the common leg have to withstand up to twice the operating current of the other inverter legs. This paper investigates the applicability of this topology for a specific constant-power two-motor drive of winder type, where these drawbacks can be to a large extent avoided. In particular, in two-motor centre-driven winders voltage requirements of two machines are hugely different during normal operation of the drive, so that the need for doubling the DC bus voltage does not take place. The current rating of the common leg does not need to be doubled either. Modelling of the centre-driven winder is summarised first. An appropriate PWM method for a two-motor drive with the common inverter leg is developed next, which allows control over how the available DC bus voltage is allocated to the two motors. Description of the five-leg inverter control scheme is further given. Detailed verification of the two-motor drive configuration is provided by simulating the operation of the centre-driven two-motor winder using the standard three-phase inverter topology and comparing the results with those obtained using the five-leg inverter configuration in conjunction with the developed PWM strategy.
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| | AC Motor Transients and EMI Emission Analysis in the ASD by Parasitic Resonance Effects Identification
By LUSZCZ Jaroslaw; IWAN Krzysztof | [View]
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Abstract: Investigation of common mode (CM) electromagnetic interference (EMI) currents in an AC motor fed by the pulse width modulated (PWM) voltage converter requires a model of the motor that take into account parasitic capacitances existing in the motor windings. Presented CM transfer impedance analysis method shows that the motor voltage transient is strongly related to the resonance effects observed on the windings CM impedance. The wide frequency CM impedance characteristics analysis allows to identify and determine resonance effects which are the primary reasons for voltage ringing phenomena. The paper presents a circuit modelling method of the AC motor windings parasitic capacitances, which allows to take into account the change of the winding to ground capacitance for different frequency ranges in the conducted frequency range. The proposed circuit model and its parameter identification method make possible more accurate CM currents modelling in the AC motor windings fed by the converter.
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| | Adjustment, measurement and on-line detection of air gap asymmetry in ac machines
By WOLBANK Thomas M.; MACHEINER Peter E. | [View]
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Abstract: The incident of fault conditions, especially bearing defects, in modern drives has increased. Bearing defect and the resulting asymmetry of the airgap is considered most difficult to detect especially under inverter operation. In order to develop and test monitoring methods it is necessary to carry out extensive measurements at various kinds and levels of eccentricity. As the air gap length of modern induction machines is in the range of a few tenth millimeters a very accurate mechanism to adjust any kind of eccentricity is needed. In this paper a test and measurement setup is described to accurately adjust and verify airgap asymmetries as well as to detect asymmetries under inverter operation. It is based on a set of eccentric rings to be placed in the bearing housings as well as on the rotor shaft. It turned out during the measurements that any industrially manufactured machine has a build in asymmetry in at least one of the different parts construction. As a result, it is still absolutely necessary to calibrate each single combination of machine housing and rotor even using very sophisticated production techniques. This verification is done primarily by a digital camera placed at different spots along the circumference of the air gap. Once the inherent asymmetries of the housing, lamination, and rotor are identified, this time consuming measurement can be replaced by a set of laser sensors placed at both sides of the machine at the rotor shaft. The performance of this setup is demonstrated by a sensitivity analysis of an asymmetry monitoring method. The analysis is done on a two pole induction machine. The monitoring method is based on a exploitation of the machines transient current slope due to the switching of the voltage source inverter.
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| | An accurate evaluation of electric discharge machining bearings currents in inverter-driven induction motors
By DE VIVO Biagio; IOVIENO Salvatore; COSTABILE Gianfranco; EGIZIANO Luigi; TUCCI Vincenzo; BENEDUCE Luigi; VITELLI Massimo; MASUCCI Antonio | [View]
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Abstract: In inverter motor drives an increasing fraction of faults is associated to the bearings damages induced by circulating currents. Current flow through the bearings is a consequence of two phenomena which, in turn, may depend on the motor speed. The first one gives rise to a conduction current through the motor bearing if a metallic contact takes place between the shaft and frame (for example, by bearing ball contact at low speed). The second one determines a discharge current when the voltage across the bearing lubricating film exceeds the film breakdown voltage (typically at high rotor angular velocity). These currents are responsible of the so called Electric Discharge Machining (EDM) of the bearings. In order to account for such damaging mechanisms an accurate model for the evaluation of bearings currents in inverter-driven induction motors has been developed and is presented in this paper. The statistical occurrence of the discharges is also taken into account in a simple but accurate way. The model allows to estimate the characteristics of the discharge pulses in typical PWM inverter driven traction motors and hence the energy levels producing the onset of the bearings' damage.
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| | Analysis and filtering of common mode and shaft voltages in adjustable speed AC drives
By STRÖM Juha; KOSKI Miia; MUITTARI Hanna; SILVENTOINEN Pertti | [View]
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Abstract: In this paper, the effects of a variable speed drive on the motor are discussed. The most typical filtering techniques are presented. A resonant LC-circuit based filter equipped with clamping diodes is introduced in more detail. The performance of the filter and the effect of the filter neutral point connection is analyzed and verified by measurements. A coaxial instrument for measuring shaft voltage is presented. The effect of the filter and common mode voltage is investigated by shaft voltage measurements.
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| | Analysis and Implementation of a 2-Degree Of Freedom Control for a Three-Phase Induction Machine
By CREVITS Yvan; LEMAIRE-SEMAIL Betty; KESTELYN Xavier | [View]
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Abstract: This paper deals with the modelling and control of a three-phase induction machine supplied by three independent voltage sources when one phase is open-circuited. The modelling of the overall system leads to design a dedicated controller tuned with the generalised stability margin method in order to reduce the pulsating torque. The consequences of the new closed-loop control on the induction machine and the VSI are evaluated to quantify the currents, voltages and copper losses increasing. Finally, simulation and experimental results are achieved and show the global performances of this ripple torque reduction method.
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| | Analytical Calculation of the RMS Current Stress on the DC Link Capacitor for a VSI Employing Reduced Common Mode Voltage PWM
By WELCHKO Brian | [View]
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Abstract: This paper derives a simple analytical expression for the rms current stress on the dc link capacitor of voltage source inverters which employ the reduced common mode voltage pulse width modulation (RCMPWM) technique. The derivation assumes the dc link voltage is constant and that the PWM switching frequency is high enough such that sinusoidal output currents are achieved. The validity of the derivation is confirmed with numerical simulations. The ac rms current which must be carried by the dc link capacitor is then a function of the modulation depth and is directly proportional to the output rms current value. This paper shows that dependant upon power factor, the rms capacitor current is increased approximately 1.3 - 2.0 times that obtained with traditional space vector PWM or discontinuous PWM methods.
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| | Assessment of an Induction Motor Drive for High Speed Operation based on Matrix Converter
By TANI Angelo; CASADEI Domenico; SERRA Giovanni; MENGONI Michele; ZARRI Luca | [View]
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Abstract: The control scheme of a speed-sensorless induction motor drive fed by a matrix converter is presented. The proposed scheme allows the motor to exploit the maximum torque capability at any speed, shows a moderate dependence on the motor parameters, and a fast torque response, even in the field-weakening speed range. The behaviour of the matrix converter is assessed by means of experimental results.
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| | Control Unit for a Laboratory Motor Test Bench for Monitoring and Controlling PMSMs and Induction Motors
By GANCHEV Martin | [View]
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Abstract: The work presents a state-of-art control unit for pulse width modulated inverter-fed AC motors. The unit is suitable for a wide range of voltage source inverters with frequencies ranging from 1KHz to up to 100KHz. The hardware is characterized by a powerful floating point DSP, FPGA unit, asynchronous serial and IEEE1394 communication interface, and 12 channels Analog/Digital interface with sample and conversion times together equaling 250ns. The control software is managed by a specially designed real-time multitasking operating system. The operating system guarantees less than 300ns time duration when jumping from one task to another upon internal or external event. The operating system can be adapted easily for arbitrary number of tasks with various prioritization levels and triggering events, and therefore suitable for interfacing hardware in the loop (HIL) simulation environments. The on-line interaction between the user and the running control software is implemented by a specially designed IEEE1394 driver for Windows XP and a graphical user interface (GUI). This allows graphical and numerical monitoring of software variables and their modification at will.
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| | Doubly Fed Induction Machine Speed Drive for Hydro-Electric Power Station
By LOWINSKY Luc Anthony; BONNET François; PIETRZAK-DAVID Maria; VIDAL Paul-Etienne | [View]
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Abstract: The main idea of this paper is to use a variable rotation speed operating mode for a Doubly Fed Induction Machine (DFIM) associated with a reversible hydraulic turbine/pump device. The optimal efficiency of the energy conversion of this system is required. A high voltage power inverter supplies the DFIM rotor windings and it allows the rotor currents control. The control expressed in this paper enables to impose active and reactive powers exchanged between the stator side and the electrical supply network. Simulation results show pump and turbine working in steady state and in transient one (starting and speed evolutions). Finally, the authors propose to study the adequate size of the high voltage power inverter.
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| | Earth-Fault Protection of VLT AutomationDrive FC 301
By ANDERSEN Henrik Rosendal | [View]
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Abstract: The earth-fault protection of VLT- AutomationDrive FC 301 is based on a single current transducer in the high-side DC-link and desaturation protection of the low-side switching elements. Used together with a novel software algorithm this makes the AC-drive earth-fault proof in any operating point.
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| | Hardware-in-the-loop simulation of the traction system of an automatic subway
By VERHILLE Jean Noel; BOUSCAYROL Alain; HAUTIER Jean-Paul; BARRE Pierre-Jean | [View]
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Abstract: A Hardware-In-the-Loop (HIL) simulation of the traction system of automatic subway VAL 206 is developed for experimental validations of new control strategies. Energetic Macroscopic Representation is used to organize the numerous blocks required. The HIL simulation is based on two vector-controlled induction machines, which impose the same behavior of the mechanical power train to the traction drives. A flexible and dynamical model of the whole system is used and experimental results are provided.
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| | High First Torque Harmonic Due to Insufficient Function of Dead-Time Compensation in PWM Inverters
By SCHAEFER Uwe; PLOTKIN Juriy; HANITSCH Rolf | [View]
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Abstract: A new source for the DC current offset in the PWM inverter-fed loads is found. A significant irregularity in dead-time voltage compensation due to a very small offset in phase current measurement is the cause for it. In the phase currents and voltages, high DC offsets appear at low current magnitudes, which lead to a first torque harmonic in the drive. Recommendations how to avoid this effect are given in the paper.
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| | Indirect Maximum Torque per Ampere Control of Induction Motor Drives
By SCARCELLA Giuseppe; CACCIATO Mario; CONSOLI Alfio; SCELBA Giacomo | [View]
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Abstract: A novel control technique is proposed aimed to efficiency optimization in scalar controlled induction motor drives. The proposed approach consists in modulating of the value of the magnetizing flux according to the load. Differently from other optimization methods, the proposed approach is based on a constant-optimal slip control, and then the model of the machine is not required to evaluate the power losses, avoiding any inaccuracy due to imperfect tuning of the motor parameters. The algorithm is based on an intuitive adaptation of the well known Maximum Torque per Ampere (MTA) control into a proper scalar control scheme able to ensure a constant-optimal slip value for efficiency optimization. The proposed control scheme is implemented using the same hardware resources as those required by conventional constant V/f or slip control implementation. An experimental evaluation has been accomplished on a 5 Hp induction motor drive in order to evaluate the efficiency improvement and dynamic response of the proposed method.
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| | Lagrange's energy method based approach for switched reluctance drive systems modelling
By MOSON Ireneusz; WILK Andrzej | [View]
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Abstract: Switched reluctance motors are often used nowadays in various industrial applications. Because of their principle of operation switched reluctance motors cannot work without a power electronic converter and a control system. Therefore not only design of individual components but also complex design of a complete switched reluctance drive system is very important. Complex approach is also necessary as far as switched reluctance drive system modelling is concerned. In the paper a method of modelling and mathematical model of a switched reluctance drive system are presented. The model derivation is based on circuit-oriented modelling methods and Lagrange's energy method. Coefficients of the Lagrange's equations have been calculated using the finite element method. The model, because of its method of derivation, is linear but allows for modelling asymmetries. Discussion on determination of model parameters for two cases - for fully symmetrical switched reluctance drive and for drive with mechanical and/or electrical asymmetries - is presented. Selected simulation results, verified against the experiment, are also presented.
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| | Loss Calculation of a Frequency Converter with a Fixed-Step Circuit Simulator
By PYRHÖNEN Juha; LAURILA Lasse; NIEMELÄ Markku; AARNIOVUORI Lassi | [View]
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Abstract: The total losses of a frequency converter are calculated by using a fast fixed-step circuit simulator. A simple model for calculating the frequency converter total losses at different operating points is presented. Direct torque control (DTC) is applied as the control method of the converter. The simulated converter losses are verified by measurements.
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| | New Compensation Method of Unbalanced 3-phase Voltage Supply in Soft-Starter for Induction Motors
By JOO Hyeonggil; CHANG Doo Won | [View]
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Abstract: In a soft-starter for 3-phase induction motor, if a 3-phase voltage supply is unbalanced, the unbalanced voltage condition gives bad influences such as a temperature rise, an increase of loss, acoustic noise and vibration, to the induction motor. In this paper, new unbalanced voltage compensation algorithm which switching angles are adjusted based on a voltage vector analysis will be presented
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| | Novel Inverter Topologies for Two-Wheel Drive Electric Vehicles with Two Permanent Magnet Synchronous Motors
By SHIBATA Minoru; HOSHI Nobukazu | [View]
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Abstract: Novel topology of an inverter that can independently control two permanent magnet synchronous motors (PMSMs) is proposed. In conventional, 12 switching devices, i.e. two three-phase three-leg inverters, are required to control two PMSMs; thus, the equipment size becomes large. The proposed inverter requires the same number of switches as the conventional inverter, i.e. only 6 switching devices. In this paper, the circuit configuration and control principle of the proposed inverter are introduced; and a controller was constructed using an FPGA. Moreover, the basic characteristics of the inverter, which is connected with two Y-connected RL loads, are shown through computer simulations and experiments. As a result, it was verified through the simulations and the experiments that the proposed inverter could output different amplitude and frequency for each load.
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| | Optimal Operation of Induction Motor Drives
By TISBORN Guido; ORLIK Bernd | [View]
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Abstract: This paper presents a new analytical model of an induction machine which can consider saturation effects in inductances. The principle is based on the idea that the air gap flux can be used to characterize the analytic function of the leakage and magnetizing inductances.
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| | Presentation of a Four-Quadrant Converter Based System in Traction Applications - Reference to Modeling, Simulation and Analysis
By MACAN Miroslav | [View]
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Abstract: This paper describes the development of an improved four-quadrant converter simulation model for AC traction drives. The functions of each of the major components of the system have been analyzed and the parameters of the model have been chosen in a way to enable building the model using IGBT modules with blocking voltage of 3.3kV. It has also been developed the simulation model of the complete energy circuit and respective control-regulation structure which encompasses: 25kV traction system, transformer model with magnetic coupling, control and regulation structure, real parameter influence of IGBT module with respect to switching losses and forward losses of IGBT and diode. The model is constructed using SIMPLORER/Schematic graphical simulation platform. Experimental results are also presented to verify the analysis and they have been recorded from the model.
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| | Real-Time Simulation of Finite-Element Analysis Permanent Magnet Synchronous Machine Drives on a FPGA card
By ABOURIDA Simon; DUFOUR Christian; BELANGER Jean; LAPOINTE Vincent | [View]
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Abstract: This paper presents a real-time simulator of a permanent magnet synchronous motor (PMSM) drive based on a finite-element analysis (FEA) method and implemented on an FPGA card for HIL testing of motor drive controllers. The proposed PMSM model is a phase domain model with inductances and flux profiles computed from the JMAG-RT finite element analysis software. A 3-phase IGBT/GTO/MOSFET inverter drives the PMSM machine. Both models are implemented on an FPGA chip, with no VHDL coding, using the RT-LAB real-time simulation platform from Opal-RT and a Simulink blockset called Xilinx System Generator (XSG). The PMSM drive, along with an open-loop test source for the pulse width modulation, is coded for an FPGA card. The PMSM drive is completed with various encoder models (quadrature, Hall effects and resolver). The overall model compilation and simulation is entirely automated by RT-LAB. The drive is designed to run in a closed loop with a HIL-interfaced controller connected to the I/O of the real-time simulator. The PMSM drive model runs with an equivalent 10 nanosecond time step (100 MHz FPGA card) and has a latency of 300 ns (PMSM machine and inverter) with the exception of the FEA-computed inductance matrix routines which are updated in parallel on a CPU of the real-time simulator at a 40 us rate. The motor drive is directly connected to digital inputs and analog outputs with 1 microsecond settling time on the FPGA card and has a resulting total hardware-in-the-loop latency of 1.3 microseconds.
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| | REDUNDANT DRIVE WITH DIRECT TORQUE CONTROL (DTC) AND DUAL-STAR SYNCHRONOUS MACHINE, SIMULATIONS AND VERIFICATION
By BURZANOWSKA Halina; SARIO Petteri; STULZ Christian | [View]
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Abstract: The performance of a drive and the quality of torque control in DTC depend on the accuracy of the estimation of flux linkage. For applications with dual-star machine each stator winding is supplied by its own inverter and the adequate stator fluxes are built. The full redundant drive is the latest development of ABB drives based on the DTC control platform. In the paper the motor model for a dual-star synchronous machine is discussed. Based on simulations with the Simulink/Matlab model of the redundant drive the operation of the drive was confirmed. Further, the concept was verified with a 1 MW motor and two ACS6000 converters in laboratory environment.
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| | Simplified Drive System Models for Power System Transient Studies in Industrial Plants
By CHEN Peiyuan; SANNINO Ambra | [View]
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Abstract: In order to simulate industrial plants for different power system transient studies, simplified adjustable speed drive (ASD) models are needed. For power system transient studies such as assessing the voltage dip ride-through capability of ASDs, detailed representation of semiconductor valve switching can be avoided, thereby making possible to increase the time step of the simulation. In this paper, simplified ASD models are developed and compared with corresponding detailed models. The performance of the simplified models is assessed when increasing the simulation step as much as possible while still maintaining the error within acceptable limits.
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| | Torsional Dynamics of Generator-Units during Autonomous Operation
By MIROSEVIĆ Marija; MILKOVIĆ Mateo; MALJKOVIĆ Zlatko | [View]
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Abstract: Abstract The main objective of this paper is to analyse dynamic behavior of diesel-generator units due to electrical loads and due to torsional strains on the shaft cable. A flexible coupling between generator rotor and rotating mass of diesel engine allows masses to rotate at a different speed in transient. In order to investigate the dynamic behavior of synchronous generator as well as torsional strains in the shaft line a unique mathematical model of integral motor drives has been developed. The model involves a prime mover, a synchronous generator with its electrical and mechanical properties and optionally, generator's control system. Mechanical coupling of a prima mover and a synchronous generator is considered a rotating system with two concentrated masses allowing thus the analysis of the torsional dynamics in the coupling.
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