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Starting from the problem of studying the parametric robustness in the case of the control of a permanent magnet-synchronous motor (PMSM), although robust control systems correspond entirely to this problem, due to the complexity of the algorithms of the robust type, in this article the use of switched systems theory is proposed as a study option, given the fact that these types of systems are suitable both for the study of systems with variable structure and for systems with significant parametric variation under conditions of lower complexity of the control algorithms. The study begins by linearizing a PMSM model at a static operating point and continues with a systematic presentation of the basic elements and concepts concerning the stability of switched systems by applying these concepts to the control system of a PMSM based on the field-oriented control (FOC) strategy, which usually changes the value of its parameters during operation (stator resistance Rs, stator inductances Ld and Lq, but also combined inertia of PMSM rotor and load J). The numerical simulations performed in Simulink validate the fact that, for parametric variations of the PMSM structure, the PMSM control switched systems preserve qualitative performance in terms of its control. A series of Matlab programs are presented based on the YALMIP toolbox to obtain Pi matrices, by solving Lyapunov–Metzler type inequalities, and using dwell time to demonstrate stability, as well as the qualitative study of the performance of PMSM control switched systems by presenting in phase plane and state space analysis of the evolution of state vectors: ω PMSM rotor speed, iq current, and id current. [ABSTRACT FROM AUTHOR]

These surrogate models replace the machine model and estimate the output parameters of the machine based on the input parameters. Induction machines are one of the most important technical applications for both the industrial world and private use. The main purpose of this paper was to develop methods to reduce the computational effort in the design and optimization of IMs using the finite element method or analytical methods. From experimentally obtained results, it was demonstrated that the brought-in scheme attained high certainty in recognizing and discriminating among different IM conditions, i.e., a machine in good physical condition, a machine with one broken rotor bar, a machine with two broken rotor bars, a machine with damage on the bearing outer race, and a machine with an unbalanced mechanical load. [Extracted from the article]

In this paper, an advanced integrator is proposed for the estimation of stator flux in a direct torque control (DTC) drive. A two‐level lookup table‐based direct torque‐controlled interior permanent magnet synchronous motor (IPMSM) drive is implemented. DTC has the inherent disadvantage of DC drift and saturation in stator flux estimation due to a pure integrator. In the proposed work, a different approach to estimate stator flux is reported overcoming the constraints of a pure integrator in DTC. An advanced integrator with an adaptive controller is implemented to determine the stator flux and enrich the performance of the drive. A comparison of transient and steady‐state analysis is carried out when IPMSM is fed by a low‐pass filter‐based DTC and proposed stator flux estimator‐based DTC. To make the system mechanically robust, stator current‐based model reference adaptive control is executed to estimate the motor speed. A mathematical derivation for the stability study of the adaptation mechanism is carried out using Popov's hyperstability criteria. The proposed algorithm is implemented in the MATLAB/Simulink environment and the soundness of the proposed work is presented by simulation results. Moreover, the experimental analysis using dSPACE1104 justifies the simulation results of the proposed system. [ABSTRACT FROM AUTHOR]

Globally abundant wave energy for power generation attracts ever increasing attention. Because of non-linear dynamics and potential uncertainties in ocean energy conversion systems, generation productivity needs to be increased by applying robust control algorithms. This paper focuses on control strategies for a small ocean energy conversion system based on a direct driven permanent magnet synchronous generator (PMSG). It evaluates the performance of two kinds of control strategies, i.e., traditional field-oriented control (FOC) and robust adaptive control. The proposed adaptive control successfully achieves maximum velocity and stable power production, with reduced speed tracking error and system response time. The adaptive control also guarantees global system stability and its superiority over FOC by using a non-linear back-stepping control technique offering a better optimization solution. The robustness of the ocean energy conversion system is further enhanced by investigating the Lyapunov method and the use of a DC-DC boost converter. To overcome system complexity, turbine-generator based power take-off (PTO) is considered. A Matlab/Simulink study verifies the advantages of a non-linear control strategy for an Oscillating Water Column (OWC) based power generation system. [ABSTRACT FROM AUTHOR]

In this study, the speed-sensorless improved field oriented control (FOC)-based induction motor (IM) drive has been presented. In addition to the rotor fluxes and rotor mechanical speed required for speed-sensorless FOC, the load torque, the stator resistance, and the rotor resistance are estimated by the switching extended Kalman filter (SEKF) with improved memory requirement and design stage which use the measured stator currents and voltages as inputs. The performance of FOC is improved by the feedforward control of the estimated load torque. In addition, the estimation errors caused by the parameter variations are reduced with the estimations of the stator and rotor resistances. The proposed speed-sensorless IM drive is tested by challenging scenarios in simulations. The results obtained demonstrate that the improved FOC-based IM drive has a high performance. [ABSTRACT FROM AUTHOR]

A new model predictive torque and flux controller is proposed, which controls the electromagnetic torque and rotor (rather than the stator) flux magnitude. Analytical expressions for the weighting factors are derived that ensure that the proposed controller achieves the same closed-loop performance as predictive current control. In particular, the same low current and torque distortions result, without requiring an outer field-oriented control loop. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a speed sensorless control scheme named as finite control set-model predictive current control (FCS-MPCC) using a modified fictitious ohmic quantity (R) based model reference adaptive system (MRAS) for grid-connected doubly-fed induction machine (DFIM) drive. The variables of the reference model of this speed sensorless scheme (R-MRAS) are represented in stationary reference frame while those for the adaptive model are denoted in synchronously rotating reference frame. The sensorless formulation thus obtained is completely independent of any stator/rotor resistance terms. The scheme is also devoid of any stator/rotor flux estimation. Moreover, the intuitiveness of FCS-MPCC brings in additional flexibility in comparison to the conventional control techniques like field oriented control (FOC) and direct torque control (DTC). The overall scheme demonstrates faster execution time than FOC/DTC based control of DFIM drive. The proposed control algorithm is simulated and tested for limited speed range application in MATLAB/Simulink. The validation of simulation results are further done by experimentation on a dSPACE-1103 based DFIM laboratory setup. Highlights • In this paper, MRAS based sensorless speed estimation of DFIM drive by FCS-MPCC is reported. • The estimation scheme insensitive to the changes in machine parameters. • The overall scheme demonstrates faster execution time than FOC/DTC based control of DFIM drive. [ABSTRACT FROM AUTHOR]

In this study, a sensorless hybrid control scheme for brushless direct current (BLDC) motors for use in multirotor aerial vehicles is introduced. In such applications, the control scheme must satisfy high-performance demands for a wide range of rotor speeds and must be robust to motor parameter uncertainties and measurement noise. The proposed controller combines field-oriented control (FOC) and direct torque control (DTC) techniques to take benefit of the advantages offered by each of these techniques individually. Simulation results demonstrate the effectiveness of the proposed control scheme over a wide range of rotor speeds as well as good robustness against parameter uncertainties within -5 to + 10% for inductance and -5 to + 5% for resistance parameters. The proposed hybrid controller is robust also against noise in voltage and current measurements. In order to verify the results from simulation, the proposed hybrid controller is implemented in hardware using the TI C2000 Piccolo Launchpad and TI BOOSTXL-DRV8305EVM BoosterPack. Testing is done with a Bull Running motor typically used in aerial drones. Testing experiments demonstrate that the hybrid controller reduces the rotor speed ripple when compared to DTC while operating in steady-state mode and decreases the response time to desired speed changes when compared to FOC. [ABSTRACT FROM AUTHOR]

The doubly fed induction machine has been traditionally adopted in adjustable-speed ac power generation drives in order to take advantage of the reduced rating for the power electronic interface. Aside this well-established application where the doubly fed induction generator (DFIG) is controlled by a back-to-back converter, recent literature records a growing interest toward un-conventional DFIG drives for dc power generation, combining DFIG high control freedom with simplified power electronic interfaces to achieve an overall cheap and fully controllable system. Despite several concepts have been demonstrated on small-scale rigs, there is a lack of systematic comparison among different topologies and control solutions. This paper bridges this gap by providing a review of recent topologies, their control, design and performance, and operation issues. As major novelties, this paper includes off-spec performance comparison of different torque-ripple mitigation strategies, discussion of sizing requirements for generator and power electronics, fundamental aspects of the behavior under voltage dips, and priorities and challenges for future research on the subject. [ABSTRACT FROM AUTHOR]

In this paper, a speed estimation method is presented, which is based on a flux observer for air-gap field orientation control (AFOC) of an induction motor (IM) drive that utilizes both air-gap flux and stator current. The stator current is obtained using Hall effect current sensors. The air-gap flux observer design was established using the Lyapunov stability theory, and the estimated rotor speed was derived from the developed flux estimator. The gain matrix parameters of the observer were adjusted by a fuzzy logic control (FLC) strategy. The MATLAB\Simulink® toolbox was used to simulate this system and all the control algorithms were realized using a TI DSP 6713-and-F2812 card to generate pulse-width modulation (PWM) signals for the power stage to actuate the motor and validate the approach. Both the simulations and experimental results verified the effectiveness of the proposed system. [ABSTRACT FROM AUTHOR]

Three-phase interior permanent magnet synchronous motor (IPMSM) drive systems have gotten widely used recently in various applications due to their speed regulation characteristics and high power density. Compared with classical field-oriented control (FOC) and flux-weakening control, model predictive control (MPC) technique is more efficient and effective in achieving excellent performance without complicated controller tuning, but with explicit constraints. Yet, the optimum application of the MPC algorithm in a machine control system is still in the exploratory stage. In order to lower the current and torque ripples, this paper retains a modulator, but replaces all the proportional integrate control loops, which are contained in the conventional FOC systems with a single MPC controller. Moreover, we adopt a brand-new linearization approach to tackle the strong coupled nonlinear IPMSM mathematical model, obtaining an improved linear plant model, which is suitable for the motor with constant load torque. When it comes to flux-weakening control, the required d-axis current is calculated, after which it is used as the input of the proposed MPC controller, abandoning the previous natural field weakening method. Finally, for the purpose of lowering the dynamic speed and current overshoot, a further constraint in the change rate of manipulated variables is discussed. The improved control algorithm has been verified in both simulation and experiment. [ABSTRACT FROM AUTHOR]

Permanent magnet ac motors have been extensively utilized for adjustable-speed traction motor drives, due to their inherent advantages including higher power density, superior efficiency and reliability, more precise and rapid torque control, larger power factor, longer bearing, and insulation life-time. Without any proportional-and-integral (PI) controllers, this paper introduces novel first- and higher-orderfield-oriented sliding mode controlschemes. Compared with the traditional PI-based vector control techniques, it is shown that the proposed field oriented sliding mode control methods improve the dynamic torque and speed response, and enhance the robustness to parameter variations, modeling uncertainties, and external load perturbations. While both first- and higher-order controllers display excellent performance, computer simulations show that the higher-order field-oriented sliding mode scheme offers better performance by reducing the chattering phenomenon, which is presented in the first-order scheme. The higher-order field-oriented sliding mode controller, based on the hierarchical use of supertwisting algorithm, is then implemented with a Texas Instruments TMS320F28335 DSP hardware platform to prototype the surface-mounted permanent magnet ac motor drive. Last, computer simulation studies demonstrate that the proposed field-oriented sliding mode control approach is able to effectively meet the speed and torque requirements of a heavy-duty electrified vehicle during the EPA urban driving schedule. [ABSTRACT FROM AUTHOR]

This paper discusses the synchronous operation of a brushless doubly fed reluctance machine (BDFRM). Basic operation theory of a ducted rotor BDFRM is reviewed, and mathematical analysis relating to synchronous operation is presented. Corresponding control strategy for synchronous speed operation is discussed. A prototype machine is built and implemented as a motor drive. Subsequently, the BDFRM drive is tested in synchronous mode of operation at varying speed levels and loads. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for the broken rotor bars fault detection is considered when the rotor speed varies continuously and the induction machine is controlled by Field-Oriented Control (FOC). The rotor fault detection is obtained by analyzing a several mechanical and electrical quantities (i.e., rotor speed, stator phase current and output signal of the speed regulator) by the Discrete Wavelet Transform (DWT) in variable speed drives. The severity of the fault is obtained by stored energy calculation for active power signal. Hence, it can be a useful solution as fault indicator. The FOC is implemented in order to preserve a good performance speed control; to compensate the broken rotor bars effect in the mechanical speed and to ensure the operation continuity and to investigate the fault effect in the variable speed. The effectiveness of the technique is evaluated in simulation and in a real-time implementation by using Matlab/Simulink with the real-time interface (RTI) based on dSpace 1104 board. [ABSTRACT FROM AUTHOR]

This paper studies the modeling and field-oriented control (FOC) for hysteresis motors, with the goal of achieving position control of hysteresis motors for servo applications. Hysteresis motors include a wide range of machines with solid cylindrical or ring-shaped steel rotors, which generate torque primarily via the magnetic hysteresis effect of the rotor material. Previously, hysteresis motors have been mainly used under open-loop operation. However, they are also attractive for position control in some special applications such as in-vacuum operation or when smooth running and high speed is required. In this paper, an equivalent circuit model for hysteresis motors that describes the motor's transient-time dynamics is introduced, and a state-space model for hysteresis motors is developed. This model is used to construct a rotor flux orientation observer for the FOC for hysteresis motors. Three methods for estimating the rotor field angle are introduced. The proposed FOC-based position control method was tested with three hysteresis motors, including two custom-made motors of different rotor materials and one off-the-shelf hysteresis motor. Experimental results show that position control for all three hysteresis motors can reach a bandwidth of 130 Hz with the proposed methods. To the authors’ best knowledge, this is the first experimental study on FOC and position control for hysteresis motors. [ABSTRACT FROM AUTHOR]

The low coupling coefficient between the transmitter and receiver is the major constraint of a wireless power transfer (WPT) system. Although some approaches, such as increasing the quality factor and achieving precise impedance matching, can reduce the adverse impacts of the low coupling coefficient and improve the system performance, high leakage magnetic flux between the transmitter and receiver remains a problem. With the increase in transfer distance and the misalignment between the transmitter and receiver, the increasing leakage magnetic flux of nondirectional fields degrades the WPT system performance. This paper proposes an active field orientation method to shape the magnetic flux so as to minimize the leakage flux. The amplitude and phase angle of the magnetizing current are controlled, and a coil structure for minimizing the coupling among the transmitters and generating a three-dimensional magnetic field is proposed. This method realizes three-dimension full-range field orientation with adjustable magnitude and direction of B-field at an arbitrary point, and as a result the B-field is concentrated with reduced leakage magnetic flux. The proposed field orientation shaping technique is verified by theoretical analysis, simulation, and experimental results. [ABSTRACT FROM PUBLISHER]

The paper proposes an improved low speed performance of classical rotor flux (RF)-based model reference adaptive system (MRAS) for field oriented controlled induction motor (IM) drives. The improved performance of the RF-MRAS estimator is obtained by using voltage reference vector to compute the rotor flux vector in the reference model instead of actual voltage signal vector in the process of speed estimation. The voltage reference vector is estimated by using proportional integral controller over the error signal vectors obtained from the difference between the reference and the measured current vectors. This modification allows satisfactory low or zero speed estimation of IM drive using RF-MRAS-based estimator. The proposed drive's performance is compared with classical RF-MRAS and its performance for the low-speed operation is also authenticated with \vecV^ * \times \vecI based MRAS in MATLAB/ Simulink. Stability and sensitivity studies are further carried out to ensure the robustness of the drive system. Experimental results as obtained by a dSPACE-1104 based IM laboratory prototype are also presented to validate the simulation study. [ABSTRACT FROM PUBLISHER]

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 simplification 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 control is widely demonstrated for a 3-phase 315 kW, 6 kV motor drive by use of computer simulation. [ABSTRACT FROM AUTHOR]

In this article, performance of field oriented controlled open-end winding induction motor drive (FOCOEWIMD) using nearest sub-hexagonal centre PWM (NSHCPWM)technique is proposed. In the proposed work, two 2-level inverters are used on either side of OEWIM drive to obtain the three-level output voltage. To generate the control signals for the two inverters, NSHCPWM technique is used. In the proposed method reference vector is realized with two components, based on the tip of the reference vector location nearest sub-hexagonal centre is identified, which is one of the switching vector used to generate the control signals for inverter-I and the other component is realized using inverter-II by mapping into the inner sub-hexagon. So that one inverter is used as switching inverter and the other is as clamping inverter. Ripples in torque and stator current are also reduced in the proposed work over conventional SVPWM techniques. Proposed work is analyzed theoretically and the same can be realized using MATLAB/SIMULINK and the corresponding results are presented for different modulation index. [ABSTRACT FROM AUTHOR]

A fixed switching period sliding mode control (SMC) for permanent-magnet synchronous machines (PMSMs) is presented. The aim of this paper is to design an SMC that improves the traditional PI-based field-oriented control transient response, as well as to reduce the switching frequency variations of the direct torque control. Such SMC requires a decoupling method of the control actions, which also brings constant switching functions slopes. These constant slopes allow to calculate the required hysteresis band value to control the switching frequency. The digital implementation degrades the performance of the hysteresis comparator, and as a consequence, the previously calculated band becomes inaccurate to regulate the switching frequency. In order to recover the analogue hysteresis band comparator performance, a predictive algorithm is proposed. Finally, a set of experimental results with constant switching frequency during a torque reversal and speed control tests are provided. [ABSTRACT FROM PUBLISHER]

This paper presents a two-degrees-of-Freedom (2DOF) and variable structure control (VSC) schemes for induction motor (IM) drives. The designed VSC incorporates independent feedback and feedforward terms as 2DOF control principle. This structure improves the response of the proposed VSC under speed reference tracking and load disturbance changes. Stability of VSC using Lyapunov theory is discussed. Due to the variable nature of the switching function of VSC, two conditions to ensure Lyapunov stability candidate are derived based on the error signal. A design criterion for the parameters of VSC are introduced to guarantee the stability. The complete IM drive system with the proposed VSC controller is built using MATLAB/Simulink. A laboratory prototype is executed experimentally using DSP-DS1104 control board. All controllers are implemented practically. Simulation and experimental results are provided under different working conditions. Performance evaluation of classic control schemes and the proposed VSC approach is presented. The proposed VSC approach gives superior behavior under speed reference variations and torque disturbances. The disturbances using the proposed controller are strongly suppressed compared to classic 2DOF control scheme. [ABSTRACT FROM AUTHOR]

A numerical scheme for the effect of flow-field orientation on water management in PEM fuel cell is developed. Since there are limitations on the location of proton exchange membrane fuel cell such as portable applications, different configurations are used for proper water management. Therefore, the best configuration must be chosen for the most efficient and stable operation of the fuel cells. In this research, a 3D numerical model is proposed based on the VOF method in order to simulate the effects of gravity on the gas–liquid two-phase flow in a full-scale single-serpentine flow-field. This model, which is validated by the experimental results, considers the microstructure of the gas diffusion layer by two square pores in every cross section along the channels. The simulations are done for the vertical and horizontal fuel cells. The effects of water coverage ratios and flow regimes on pressure drop and the resulting parasitic power loss are investigated for different configurations. In the vertical orientation, the channels are placed horizontally or vertically in each configuration. The results reveal that in the vertical cells, when the channels are located horizontally and the inlet manifold is embedded on the upper side of the flow-field, the pressure drop is the lowest. The reason is that the film flow is formed in the channels and the gravity assists in the water removal. However, when both the cell and channels are vertical and the cathode inlet manifold is placed on the bottom of the flow-field, the pressure drop and the resulting parasitic power is the highest. This is due to the gravity is against the water purging from the elbows leading to formation of long plugs along the channels. The present numerical model can be used for simulation of two-phase flow in channels of the serpentine flow-field at any cell orientation angle by changing the gravity direction in the model. [ABSTRACT FROM AUTHOR]

Propulsion system used in applications like electric traction, rolling stock, etc. requires high torque at low speed for starting and climbing and nearly constant power at high speed. Induction machines, which are rugged, reliable, low cost and has less maintenance, satisfy the characteristics of the propulsion and reinstating the traditionally used DC series motor for this purpose. Field oriented control (FOC) of induction machines can decouple its torque control from field control and extended speed range operation with constant power beyond rated speed by field weakening (FW). It is desirable to retain maximum torque capability in the FW region for propulsion applications at high speed. To produce maximum torque that machine could possibly develop at FW region, the maximum inverter voltage and current must be appropriately utilized. This paper proposes an innovative approach to improve the torque capability of induction machine in FW region by modifying the design of induction machine to change the bahaviour of the machine to suit propulsion requirements. Extensive simulation of the design options generated from the design modification has been carried out using MATLAB/Simulink and torque-speed characteristics are compared. [ABSTRACT FROM AUTHOR]

This paper introduces new schemes for detection, isolation, and compensation of speed and current sensor (CS) faults in field oriented induction motor (IM) drives. These schemes do not use any kind of machine model and motor parameters. This is a prominent feature of the proposed approaches, which only rely on main concepts of field-oriented control (FOC)-based IM drives. Moreover, the proposed fault detection and isolation (FDI) schemes can take partial sensor failures into account. These kinds of faults that might be caused by mechanical or electrical failures, or intentional sensor tampering, are difficult to be dealt with since embedded speed and current control loops react swiftly, and inherently try to camouflage partial sensor failures. CS faults result in imbalance current flow in the motor stator phases, and speed sensor fault repudiates the orthogonally alignment of field and torque current components in field oriented IM drives. These features are cornerstones of introduced FDI methodology. Furthermore, model and parameter free compensators are proposed to recover normal operation of the machine before fault incident. After in-depth analysis, extensive simulation and experimental tests validate the proposed schemes. [ABSTRACT FROM AUTHOR]

Electromagnetic torque and stator flux of a permanent magnet synchronous motor (PMSM) can be controlled indirectly with model predictive current control (MPCC). In MPCC, a predefined cost function is minimised by selecting and applying appropriate voltage vectors to stator terminals. Since MPCC employs machine model to predict stator currents, it requires accurate knowledge of its parameters. Furthermore, MPCC results in high torque and current ripples at normal sampling rates. In this study, torque and current ripples of a surface-mounted PMSM are effectively reduced by incorporating the concept of duty cycle and applying two voltage vectors, instead of one voltage vector as in conventional MPCC, during a control period. A fuzzy logic modulator is designed and utilised to determine the duty cycles of voltage vectors. Furthermore, sensitivity of the proposed control strategy against parameter variations is alleviated by employing a full-order Luenberger observer. Various case studies are carried out on a hardware-in-the-loop setup and performance of the proposed method is compared with conventional and a recently introduced duty cycle-based predictive control. The obtained results verify the superiority of the proposed MPCC and its effectiveness in reducing the PMSM torque and current ripples with accurate and erroneous knowledge of motor parameters. [ABSTRACT FROM AUTHOR]

Two cascaded two-level inverters can synthesise three-level voltage space vector. For the cascaded three-level inverter controlled induction motor, this study proposes a five-level torque controller (FLTC)-based direct torque control (DTC) method especially for improving steady-state motor torque performance and retaining the high dynamic performance. The proposed FLTC method employs hysteresis controllers, uses look-up tables and ends up with variable switching frequency of the cascaded three-level inverter. Computationally, the envisaged FLTC method is quite comparable to that of the basic DTC method. The FLTC method ensures reduced switching commutations in the inverter switching devices during low speeds of operation and simultaneously achieves reduced dv/dt switching stresses. An inherent drawback of FLTC method at higher speeds of operation is identified, theoretically analysed and a pseudo error-based correction is also suggested in this study to overcome the drawback. The steady-state and transient motor torque performance of the induction motor with the use of the envisaged FLTC-based DTC method is thoroughly analysed, simulated using Matlab/Simulink and then experimentally validated on a laboratory prototype for starting, speed reversal and load change conditions with the use of the cascaded three-level inverter. [ABSTRACT FROM AUTHOR]

A synchronous current controller for field-oriented control is a popular control scheme that is used in industry to separately control the synchronous current of an induction motor in steady state. However, in some transient states such as during start-up and variation of the mechanical load, the synchronous current along the d -axis remains coupled to the q-axis current. Conventional decoupling current control considers only the model of an induction motor to compensate these coupling terms, but the motor is often powered by an inverter, which also influences the current, voltage, and torque behavior. Thus, a novel decoupling current control method is proposed to consider the coupling terms of both the motor and power converter in a synchronous current controller. Existing approaches assume that the motor is directly connected to the power supply, so a model is also suggested for a pulse width modulation (PWM) inverter. Analytical equations with simulation and experimental results prove that the coupling terms are still present when not considering the PWM inverter in the decoupling network. The proposed method shows good performance, and the d-axis current is always separated from the q-axis current during variation of the mechanical load. [ABSTRACT FROM PUBLISHER]

Compared to the widespread modulation-based control strategies such as field oriented control (FOC), MPC eliminates the use of internal current control loops and modulation block, hence featuring very quick dynamic response. Furthermore, MPC well respects the discrete nature of power converters by evaluating the influence of each voltage vector on the concerned control variables, which are usually combined into a cost function, hence featuring simple concept. In spite of the merits of quick response and conceptual simplicity, it seems that MPC may be inferior to FOC in terms of steady-state performance, especially in the low speed range, which is usually a drawback of MPCbranched methods. This study proposes an improved two-vectors-based MPC (MPC2) and compares it to the wellestablished FOC. A detailed experimental study of both methods is presented, including steady-state performance, dynamic response, low speed operation and control complexity. Very promising results are obtained in MPC2 by providing better steady-state performance and much quicker response than FOC under the condition of similar average switching frequency. The results prove that MPC2 is a powerful alternative to FOC and may find wide applications in the near future. [ABSTRACT FROM AUTHOR]

A new four quadrant Field Orientation-Controlled (FOC) three-phase induction motor drive based on Hysteresis Current Comparison (HCC) has been developed. The direct relationship between current and torque in the Direct-Quadrature (dq) reference frames has been exploited to develop an HCC scheme that offers accurate tracking of current and torque based on the pulse width modulation technique. The parameters of the inner HCC and the outer Proportional-Integral (PI) speed controllers have been optimised to obtain effective current and torque tracking. The complete closed loop system being speed-controlled, four quadrant operation has been obtained using step speed input while the suitability of the developed model has been tested under full load stress during steady state. The results obtained satisfy the four quadrant operation requirements of advanced drives where controlled starts and stops are essential in both forward and reverse directions. This is evident in the effectiveness of current and torque tracking and ease of speed transition from motoring to regeneration and vice versa. The developed model finds applications in advanced industrial drives as an energy-efficient and cost-effective alternative to eliminate the effects of supply voltage drops and mechanical load variations. [ABSTRACT FROM AUTHOR]

This paper presents a comparison between Sensor or Indirect Field Oriented Control (IFOC) and Sensor-less Field Oriented Control (SFOC) in low frequency region for Induction Motor (IM). These two strategies can be considered among the family of Vector Control (VC) methods and provide a solution for high-performance drives. Most of the Electrically-operated Overhead Travelling (EOT) Crane IMs are controlled with vector control techniques. IM performance will deteriorate as frequency falls below 5 Hz due to its stator resistance drop. There are some critical requirements which needs rocket segments and satellite needs to be positioned in very precise position. For this EOT crane has to run in creep speed which needs drive has to run below 5 Hz. In this paper, the analysis is carried out on IFOC and SFOC methods and implemented to IM drives. In IFOC, flux magnitude and angle is achieved by imposing a slip frequency derived from the rotor dynamic equations with monitored rotor speed using external sensor such as encoder. Whereas SFOC does not require any sensor for estimation of flux magnitude and position, with monitored stator voltages and stator currents, flux magnitude and position can be achieved. Advantages and disadvantages of two control methods are emphasized in low frequency region (0-5 Hz). The theoretical results are found to be consistent with experimental results performed on 100 HP, three phase IM. It is concluded that IFOC method is better than SFOC method in low frequency region. [ABSTRACT FROM AUTHOR]

A sensorless stand-alone control scheme of a doubly fed induction generator (DFIG)-DC system is investigated in this paper. In this layout, the stator voltage is rectified by a diode bridge that is directly connected to a dc bus. The rotor-side voltage source inverter is the only controlled converter required in this system and is directly powered by the same dc bus created by the stator-side rectifier. DC voltage and stator frequency are regulated by two independent proportional-integral regulators that give the references for inner current controllers implementing field-oriented control. As it is capable of creating a stable and regulated dc bus, this system can be conveniently adopted to supply dc loads or to form a dc grid. Due to the constraint imposed by the stator diode bridge, the DFIG has to operate under a constant stator voltage, and the conventional stator field-oriented control implemented in stand-alone ac DFIG must be modified. This paper presents the control structure and the theoretical framework for the controller synthesis. Simulation and experimental validations on a small-scale rig are included. [ABSTRACT FROM PUBLISHER]

In this paper a transistor open-circuit fault diagnosis method in a rotor field oriented controlled induction motor drive, fed by a two-level voltage inverter has been proposed. The diagnostic procedure ensures detection and localization of single or multiple power switch failures in time shorter than one period of a stator current fundamental harmonic, without regard to a drive operation point. A new simple scheme of the diagnostic system is proposed. In order to validate the proposed transistor fault diagnostic method, a detailed simulation as well as experimental tests of the field-oriented control drive system were carried out and some of them are shown in this paper. [ABSTRACT FROM AUTHOR]

Modern drives consist of alternating current electric motors, and the field-oriented control (FOC) of such motors enables fast, precise, and robust regulation of a drive's mechanical variables such as torque, speed, and position. The control algorithm, implemented in a microprocessor, requires feedback from motor currents, and the quality of this feedback is essential to a drive's control properties. Motor phase currents are sampled and processed in order to extract their mean over a digital control interval. Afterwards, the mean phase currents are transformed into a rotating field-oriented reference frame to enable controlling the mechanical variables. The field-oriented frame rotates continuously, but in practice the transformation is carried out using a discrete angular position. This paper investigates how the discretization impacts the computed field-oriented currents in high speed drives, where the rotor displacement during a control interval is substantial. A continuous-time model of field-oriented currents is indicated as a reference to quantify errors. An original approach to normalize variables and to solve the model analytically is proposed in order to investigate how the errors related to rotor position discretization are influenced by drive operating conditions. The analytical solution is validated by computer simulation. The results show that the currently applied methodology of computing field-oriented current components, due to an invalid assumption, introduces errors of a few percent when a drive operates at high speed. These errors can be compensated using the presented solution. [ABSTRACT FROM AUTHOR]

A high performance hysteresis current control of a permanent magnet synchronous motor (PMSM) drive is developed in this paper. The core advantage of field orientation control (FOC) is utilized to separate the ux and torque control components of the stator current of the PMSM. Specifically, the objectives of this work are to develop and utilize the HCC algorithm for FOC of a complete closed-loop speed-controlled PMSM drive system, optimize the control algorithm to obtain fast speed response while maintaining effective current and torque tracking, and examine the hysteresis current control action clearly showing the inverter switching and the effects of hysteresis band selection. Being a speed-controlled system, the suitability of the developed model with constant, step, and ramp reference speed inputs is examined. The results obtained show that the developed model and algorithm based on hysteresis current control offer effective current and torque in all scenarios tested. [ABSTRACT FROM AUTHOR]

This two-part paper aims at providing the basic mathematical theory of omnidirectional wireless power transfer (WPT). Based on current vector control, the magnetic field vector can be generated and pointed at any direction, thus achieving genuine omnidirectional wireless power flow. Part-I of this paper contains the mathematical analysis of the two-dimensional (2-D) system. The 2-D analysis shows that the total input power and the system energy efficiency of the WPT system can be expressed as functions of the angle of the input magnetic field vector. These functions follow the Lemniscates of Bernoulli on the 2-D plane. The directional nature of such curves provides the crucial information of the locations of the receivers so that the wireless power can theoretically be directed to the loads efficiently. The 2-D theory is presented here with the support of experimental verification. Understanding the 2-D omnidirectional WPT theory would make it relatively easy to appreciate the three dimensional one reported in Part II. [ABSTRACT FROM AUTHOR]

Many induction motor speed controllers contain a speed or position sensor. This last is required to provide accurate measurement. A faulty speed sensor decreases the controller performance dramatically. Hence, a fault diagnosis and detection technique is necessary. This paper deals with several faults which affect the speed sensor used in an induction motor vector controlled drive. Three different faults are considered; offset fault, uncertainty of measurement, and total loss of feedback information. Then a detection strategy is suggested based on the computation of the energy of the average standard deviation of speed data. Simulation on Matlab/Simulink and experiments were carried out to show the effect of each fault on the vector control performance and to verify the effectiveness of the proposed detection scheme. [ABSTRACT FROM AUTHOR]

In this paper, a novel model predictive control (MPC) scheme is proposed for field-oriented control of permanent magnet synchronous motor fed by voltage-source inverter, in which a hybrid control set (HCS) including active-vectors with duty cycle and virtual vectors with duty cycle can be established. Since more vectors with different angles and duty cycles are available, the proposed approach is capable of adjusting the magnitude and angle of the output vector finely. However, the duty cycle of vectors in HCS is countless, so the total of elements in HCS is actually infinite. In order to select the optimal vector from HCS, we transform the original MPC optimization problem. By means of finite enumerations and evaluations online, the optimal solution can be obtained, which includes both angle and duty cycle of the output vector. In addition, a simplified solving algorithm is also presented, which can further reduce the computational cost. Finally, the feasibility and effectiveness of the proposed approach can be validated by experimental results. [ABSTRACT FROM PUBLISHER]

This paper focuses the hardware realization and implementation of speed-sensorless field oriented control of induction motor drive. For speed sensorless operation, natural observer is applied to estimate the stator currents, rotor fluxes, load torque and rotor speed because of its simple structure and no direct feedback. The configuration of the natural observer is comparable to and as well as its feature is identical to the induction motor. State space model is applied to both the estimator and the induction motor. Load torque adaptation is provided to estimate the load torque and, speed is estimated from the torque, rotor fluxes and stator currents. Direct field oriented sensorless vector control scheme is used and the rotor angle is calculated from the estimated rotor fluxes. Simulations as well as experimental results are presented for various speed and load conditions to demonstrate the performance of natural observer in sensorless vector control applications. [ABSTRACT FROM AUTHOR]

This paper proposes the optimization of the PI gain used in the speed control of permanent magnet synchronous motor (PMSM). The optimization technique used in this project is Particle Swarm Optimization (PSO). In this project, field oriented control (FOC) is used to control the speed of the PMSM. The PSO is used to find the finest gain of the speed-PI so that the speed error will be minimized and it is designed to achieve the specific objective function. In this paper, the objective is to reduce the steady state error of the system drive. By randomly initialize, these particles fly through the search space dimension to evaluate and updating their positions and velocity. As updating the position and velocity, the personal and global best value also keep updating until it finds better fitness and achieve the optimal value. The simulation results proved that the proposed technique can reduce the speed error close to zero and get the better result compared to the heuristic method. [ABSTRACT FROM AUTHOR]

The mathematical model of the five-phase squirrel-cage induction motor and the system of the dual five-phase voltage source inverter have been presented. The control methods and control systems of the field-oriented control of the five-phase induction motor with an open-end stator winding are described. The structures of the direct fieldoriented control system (DFOC) and the Indirect Field-oriented control system (IFOC) with PI controllers in outer and inner control loops are analyzed. A method of space vector modulation used to control the system of the dual five-phase voltage source inverter has been discussed. The results of simulation studies of the field-oriented control methods are presented. Comparative analysis of the simulation results was carried out. [ABSTRACT FROM AUTHOR]

This paper develops an appropriate predictive current controller (PCC) for fast torque monitoring and high-performance operation of a permanent-magnet synchronous motor (PMSM) drive involving constant switching frequency. The proposed controller is based on a convenient combination of deadbeat and direct predictive control (DPC) techniques. Its response is compared to that of a typical proportional–integral (PI) current controller in field-oriented control (FOC) strategy. The analysis illustrated improved transient characteristics concerning faster speed changes as well as reduced current and torque ripple while it enables additional control criteria inclusion. The simulated results have been validated by measurements on a test bench. [ABSTRACT FROM PUBLISHER]

This paper discusses the d-q model and winding function method (WFM) for modeling and a rotor fieldoriented control (RFOC) system for controlling a faulty three-phase induction motor (three-phase IM when one of the phases is disconnected). In the adapted scheme for controlling the faulty IM, it is necessary for the PI controller coefficients to change. For this purpose, the gravitational search algorithm (GSA) is used for tuning of PI controllers. The results show the strength and ability of the technique to improve the performance of the faulty IM control. [ABSTRACT FROM AUTHOR]

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This paper presents a novel predictive model reference adaptive system (MRAS) speed estimator for sensorless induction motor (IM) drives applications. The proposed estimator is based on the finite control set-model predictive control (FCS-MPC) principle. The rotor position is calculated using a search-based optimization algorithm which ensures a minimum speed tuning error signal at each sampling period. This eliminates the need for a proportional–integral (PI) controller which is conventionally employed in the adaption mechanism of MRAS estimators. Extensive experimental tests have been carried out to evaluate the performance of the proposed estimator using a 2.2-kW IM with a field-oriented control (FOC) scheme employed as the motor control strategy. Experimental results show improved performance of the MRAS scheme in both open- and closed-loop sensorless modes of operation at low speeds and with different loading conditions including regeneration. The proposed scheme also improves the system robustness against motor parameter variations and increases the maximum bandwidth of the speed loop controller. [ABSTRACT FROM PUBLISHER]

High-performance electrical drives can be achieved by using field-oriented controllers, which make torque and flux naturally decoupled. A conventional vector-controlled drive has the disadvantage of either requiring flux and speed sensors or being affected by rotor resistance, which varies along with the motor performance. The presented paper focuses on developing a high-performance sensorless rotor flux-oriented controller of an induction machine independent of the rotor resistance variation. This method applies spectral theory of Walsh functions, which are one of the most helpful members of piecewise constant basis functions in solving dynamic models. Inherent characteristics of Walsh functions and application of an operational matrix will make the system handy and robust against inverter switching effects. [ABSTRACT FROM AUTHOR]

With increase in electric power demand, transmission lines were forced to operate close to its full load and due to the drastic change in weather conditions, thermal limit is increasing and the system is operating with less security margin. To meet the increased power demand, a doubly fed induction generator (DFIG) based wind generation system is a better alternative. For improving power flow capability and increasing security STATCOM can be adopted. As per modern grid rules, DFIG needs to operate without losing synchronism called low voltage ride through (LVRT) during severe grid faults. Hence, an enhanced field oriented control technique (EFOC) was adopted in Rotor Side Converter of DFIG converter to improve power flow transfer and to improve dynamic and transient stability. A STATCOM is coordinated to the system for obtaining much better stability and enhanced operation during grid fault. For the EFOC technique, rotor flux reference changes its value from synchronous speed to zero during fault for injecting current at the rotor slip frequency. In this process DC-Offset component of flux is controlled, decomposition during symmetric and asymmetric faults. The offset decomposition of flux will be oscillatory in a conventional field oriented control, whereas in EFOC it was aimed to damp quickly. This paper mitigates voltage and limits surge currents to enhance the operation of DFIG during symmetrical and asymmetrical faults. The system performance with different types of faults like single line to ground, double line to ground and triple line to ground was applied and compared without and with a STATCOM occurring at the point of common coupling with fault resistance of a very small value at 0.001 Ω. [ABSTRACT FROM AUTHOR]

The Permanent Magnet Synchronous Motor (PMSM) is commonly used as traction motors in the electric traction applications such as in subway train. The subway train is better transport vehicle due to its advantages of security, economic, health and friendly with nature. Braking is defined as removal of the kinetic energy stored in moving parts of machine. The plugging braking is the best braking offered and has the shortest time to stop. The subway train is a heavy machine and has a very high moment of inertia requiring a high braking torque to stop. The plugging braking is an effective method to provide a fast stop to the train. In this paper plugging braking system of the PMSM used in the subway train in normal and fault-tolerant operation is made. The model of the PMSM, three-phase Voltage Source Inverter (VSI) controlled using Space Vector Pulse Width Modulation technique (SVPWM), Field Oriented Control method (FOC) for independent control of two identical PMSMs and fault-tolerant operation is presented. Simulink model of the plugging braking system of PMSM in normal and fault tolerant operation is proposed using Matlab/Simulink software. Simulation results for different cases are given. [ABSTRACT FROM AUTHOR]

This paper investigates sensorless indirect field oriented control (IFOC) of SLIM with full-order Luenberger observer. The dynamic equations of SLIM are first elaborated to draw full-order Luenberger observer with some simplifying assumption. The observer gain matrix is derived from conventional procedure so that observer poles are proportional to SLIM poles to ensure the stability of system for wide range of linear speed. The operation of observer is significantly impressed by adaptive scheme. A fuzzy logic control (FLC) is proposed as adaptive scheme to estimate linear speed using speed tuning signal. The parameters of FLC are tuned using an off-line method through chaotic optimization algorithm (COA). The performance of the proposed observer is verified by both numerical simulation and real-time hardware-in-the-loop (HIL) implementation. Moreover, a detailed comparative study among proposed and other speed observers is obtained under different operation conditions. [ABSTRACT FROM AUTHOR]

Doubly fed induction generator (DFIG) is a better alternative to increased power demand. Modern grid regulations force DFIG to operate without losing synchronism during overvoltages called high voltage ride through (HVRT) during grid faults. Enhanced field oriented control technique (EFOC) was proposed in Rotor Side Control of DFIG converter to improve power flow transfer and to improve dynamic and transient stability. Further electromagnetic oscillations are damped, improved voltage mitigation and limit surge currents for sustained operation of DFIG during voltage swells. The proposed strategy has advantages such as improved reactive power control, better damping of electromagnetic torque oscillations, and improved continuity of voltage and current from stator and rotor to grid during disturbance. In EFOC technique, rotor flux reference changes its value from synchronous speed to zero during fault for injecting current at the rotor slip frequency. In this process, DC-Offset component of stator flux is controlled so that decomposition during overvoltage faults can be minimized. The offset decomposition of flux will be oscillatory in a conventional FOC, whereas in EFOC it is aimed to be quick damping. The system performance with overvoltage of 1.3 times, 1.62 times, and 2 times the rated voltage occurring is analyzed by using simulation studies. [ABSTRACT FROM AUTHOR]