Sensorless Control

Based on the two-dimensional (2-D) least squares method, this paper presents a novel numerical method to calculate the magnetic characteristics for switched reluctance motor drives. In this method, the 2-D orthogonal polynomials are used to model the magnetic characteristics. The coefficients in these polynomials are determined by the 2-D least squares method. These coefficients can be computed off line and can also be trained on line. The computed results agree well with the experimental results. In addition, the effect of the order number of the polynomials on the computation errors is discussed. The proposed method is very helpful in torque prediction, simulation studies and development of sensorless control of switched reluctance motor drives.

Sensorless operation of permanent magnet brushless direct current (BLDC) motor drive controls the rotating speed with different applied voltage. No phase lagging is produced which leads to increase the efficiency and minimize the torque pulsation of the BLDC motor. Initially, motor can be started by following the v/f method then allows the sensorless mode after reaching the minimum speed of 500-1000rpm. The Sensorless BLDC motors are highly used due to higher efficiency, reliability power, acoustic noise, smaller, lighter, greater dynamic response, better speed versus torque characteristics, higher speed range and longer life. Thus, the source voltage spikes and switching losses are reduced. This method can be demonstrated through MATLAB simulation and DSP TMS 320LF2407A is used in the experimental setup to get the output.

In the present paper the complete process of grid connection of a Doubly Fed Induction Machine (DFIM) based wind energy generation system without position sensors is described in detail. A sensorless position estima- tion algorithm based on axes transformation is used. The sensorless algorithm has been tested in all the different stages, from acceleration, through grid connection to active power extraction. A new grid synchronization method without position sensors is proposed.

In the motor control industry, digital signal processor (DSP) systems offer major improvements compared to analogue designs, notably enabling to replace speed or position sensors by the implementation of sensorless control algorithms. A new viable method that estimates the rotor velocity of a permanent magnet DC-motor from the 'rotor slot harmonics' present in the DC current signal is proposed. This approach is based on both two adaptive digital filters and a frequency estimator, which is fitted to this particular application and compared to a classical technique. Finally, an algorithm that selects the best speed estimation to reach high-speed transient behaviour and to obtain speed estimation error equal to zero at steady state is proposed.

This paper develops a simple sensorless control algorithm for an induction motor. An observerless controller is proposed, which guarantees local asymptotic speed tracking-flux regulation under condition of constant load torque. The controller development is based on the decomposition of the induction machine model in two coupled subsystems: electromechanical and electromagnetic, achieved by means of indirect field-oriented transformation. The experimental results demonstrate the steady-state and dynamic performance suitable for general industrial applications.

This paper presents a sensorless technique for highperformance induction machine drives based on neural networks. It proposes a reduced order speed observer where the speed is estimated with a new generalized least-squares technique based on the minor component analysis (MCA) EXIN + neuron. With this regard, the main original aspects of this work are the development of two original choices of the gain matrix of the observer, one of which guarantees the poles of the observer to be fixed on one point of the negative real semi-axis in spite of rotor speed, and the adoption of a completely new speed estimation law based on the MCA EXIN + neuron. The methodology has been verified experimentally on a rotor flux oriented vector controlled drive and has proven to work at very low operating speed at no-load and rated load (down to 3 rad/s corresponding to 28.6 rpm), to have good estimation accuracy both in speed transient and in steady-state and to work correctly at zero-speed, at no-load, and at medium loads. A comparison with the classic full-order adaptive observer under the same working conditions has proven that the proposed observer exhibits a better performance in terms of lowest working speed and zero-speed operation.

Induction motor (IM) speed sensorless control, allowing operation at low and zero speed, optimizing torque response and efficiency, will be presented in this paper. The magnitude and the orientation angle of the rotor flux of the IM are determined by the output of the closed-loop rotor-flux observer based on the calculation of the extended electromotive force of the machine. The proposed rotor-flux-oriented control scheme is robust to parameter variations and external disturbances. Both observer and controller utilize the continuous sliding mode and Lyapunov theory. A smooth transition into the field-weakening region and the full utilization of the inverter current and voltage capability are thus possible. The produced torque is a continuous output variable of control. The performance of the proposed method is investigated and verified experimentally on a digital signal processor.

This paper proposes a new approach to a sensorless speed control and an initial rotor position estimation a salient pole Permanent Magnet Synchronous Motor (PMSM) drive. The estimation of the position and of the speed in dynamic rate were derived by the use of the extend Kalman filter algorithm by only measuring the phase voltages and motor currents. For the starting with a maximum torque and an imposed rotation way, it is necessary to know the initial position. The starting procedure is a problem under sensorless drives, because no information is available before starting. In this work, we shall establish a new convenient technique for detecting the rotor initial position, based on signal tests applied to the stopped machine. The validity of the proposed sensorless control strategy, according to the different initial rotor position conditions are discussed and simulation results are presented. The experimental results show very well the validity of the proposed method for the estimation of the initial rotor position of the PMSM.

This paper proposes a novel and simple direct power control of three-phase pulsewidth-modulated (PWM) rectifiers with constant switching frequency using space-vector modulation (DPC-SVM). The active and reactive powers are used as the pulse width modulated (PWM) control variables instead of the three-phase line currents being used. Moreover, line voltage sensors are replaced by a virtual flux estimator. The theoretical principle of this method is discussed. The steady-state and dynamic results of DPC-SVM that illustrate the operation and performance of the proposed system are presented. It is shown that DPC-SVM exhibits several features, such as a simple algorithm, good dynamic response, constant switching frequency, and particularly it provides sinusoidal line current when supply voltage is not ideal. Results have proven excellent performance and verify the validity of the proposed system.

The paper presents a comparison of methods of the back EMFs estimation for the permanent magnets synchronous motor in a case of position estimation at the low speed range. These methods are based on the following structures for back EMF estimation: observer for model of the electrical part of the motor, the observer for the modified correction function and estimation based on the simplified model. Obtained in this way the instantaneous values of the back EMFs, depending on the method of obtaining them, are characterized by different quality and accuracy of the estimated shaft position.

Control techniques for PWM rectifiers in ac adjustable speed drives are presented. In particular, the so-called virtual flux-oriented control (VFOC) and virtual flux-based direct power control (VF-DPC) schemes are described and compared with their voltage-based counterparts, that is, the voltage-oriented control (VOC) and voltage-based direct power control (V-DPC) techniques. Theoretical background is provided, and results of computer simulations and laboratory experiments are given, documenting advantages and disadvantages of the individual control strategies.

This paper presents a new sensorless method for the vector control of Doubly-Fed Induction Machines (DFIMs) without using speed sensors or rotor position measurements. The proposed sensorless method is based on the Model Reference Adaptive System (MRAS) estimating the rotor position and speed from the machine rotor currents. The method is appropriate for both stand-alone and grid-connected operation of variable speed DFIMs. To design the MRAS observer with the appropriate dynamic response, a small signal model is derived. The sensitivity of the method for variation in the machine parameters is also analyzed. Speed catching on the fly and synchronization of the Doubly-Fed Induction Generator with the utility are also addressed. Experimental results obtained from a 3.5-kW prototype are presented and fully analyzed.

The paper proposes a motion-sensorless control method for permanent magnet synchronous motor drives when only the DC-link current is measured instead of the motor phase currents. A two-phase pulse-width modulation method is used, allowing the DC-link current to be sampled twice in a switching period at uniform intervals during active voltage vectors. A method is proposed for obtaining the current feedback for vector control, and an adaptive observer is used for estimating the rotor speed and position. The estimation is augmented with a highfrequency signal injection method at low speeds; a modified highfrequency excitation voltage is proposed for better performance. The proposed method enables stable operation of the permanent magnet synchronous motor drive in a wide speed range and under various loads. The effectiveness of the proposed method is demonstrated both by simulations and laboratory experiments.

In this paper, a low-time-consuming and low-cost sensorless-control algorithm for high-dynamic performance permanent-magnet synchronous motors, both surface and internal permanent-magnet mounted for position and speed estimation, is introduced, discussed, and experimentally validated. This control algorithm is based on the estimation of rotor speed and angular position starting from the back electromotive force space-vector determination without voltage sensors by using the reference voltages given by the current controllers instead of the actual ones. This choice obviously introduces some errors that must be vanished by means of a compensating function. The novelties of the proposed estimation algorithm are the position-estimation equation and the process of compensation of the inverter phase lag that also suggests the final mathematical form of the estimation. The mathematical structure of the estimation guarantees a high degree of robustness against parameter variation as shown by the sensitivity analysis reported in this paper. Experimental verifications of the proposed sensorless-control system have been made with the aid of a flexible test bench for brushless motor electrical drives. The test results presented in this paper show the validity of the proposed low-cost sensorless-control algorithm and, above all, underline the high dynamic performances of the sensorless-control system also with a reduced equipment.

The aim of this thesis is to develop a sensorless control strategy for an oscillating linear
permanent magnet synchronous motor.
The state-of-the-art sensorless methods are examined and their reliability to linear drives
is discussed. Subsequently, an adaptive sliding mode concept is chosen to estimate the
position of the mover. In the next step, the concept is implemented and simulated in
Matlab-Simulink. The results are discussed in detail.
Finally, the concept is implemented in the rapid-prototyping software X2C and evaluated
on the real plant. The results conrm the functionality of the concept for an oscillating
operation of the linear motor. The attainable accuracy of the stroke control is veried
with different levels of load. The limitations of the use of the investigated concept are shown.

This paper provides a technical review of position and speed sensorless methods for controlling Brushless Direct Current (BLDC) motor drives, including the background analysis using sensors, limitations and advances. The performance and reliability of BLDC motor drivers have been improved because the conventional control and sensing techniques have been improved through sensorless technology. Then, in this paper sensorless advances are reviewed and recent developments in this area are introduced with their inherent advantages and drawbacks, including the analysis of practical implementation issues and applications. The study includes a deep overview of state-of-the-art back-EMF sensing methods, which includes Terminal Voltage Sensing, Third Harmonic Voltage Integration, Terminal Current Sensing, Back-EMF Integration and PWM strategies. Also, the most relevant techniques based on estimation and models are briefly analysed, such as Sliding-mode Observer, Extended Kalman Filter, Model Reference Adaptive System, Adaptive observers (Full-order and Pseudoreduced-order) and Artificial Neural Networks.

In this paper, the position-sensorless direct torque and indirect flux control of brushless dc (BLDC) motor with nonsinusoidal back electromotive force (EMF) has been extensively investigated. In the literature, several methods have been proposed for BLDC motor drives to obtain optimum current and torque control with minimum torque pulsations. Most methods are complicated and do not consider the stator flux linkage control, therefore, possible high-speed operations are not feasible. In this study, a novel and simple approach to achieve a low-frequency torque ripple-free direct torque control (DTC) with maximum efficiency based on dq reference frame is presented. The proposed sensorless method closely resembles the conventional DTC scheme used for sinusoidal ac motors such that it controls the torque directly and stator flux amplitude indirectly using d-axis current. This method does not require pulsewidth modulation and proportional plus integral regulators and also permits the regulation of varying signals. Furthermore, to eliminate the low-frequency torque oscillations, two actual and easily available line-to-line back EMF constants (k ba and k ca ) according to electrical rotor position are obtained offline and converted to the dq frame equivalents using the new line-to-line park transformation. Then, they are set up in the look-up table for torque estimation. The validity and practical applications of the proposed sensorless three-phase conduction DTC of BLDC motor drive scheme are verified through simulations and experimental results.

This paper develops a brushless DC motor control technique without using any sensors. Back emf of motor is considered as a parameter for commutation. Also this system incorporates cuk converter as a power factor correction converter for PMBLDC motor fed through a diode bridge rectifier from a single phase AC mains. Three phase VSI is used in this system as an electronic commutator for BLDC motor based compressor in an air conditioner. Here the proportionality between Dc link voltage and speed is considered and speed control in this system is attained by maintaining this proportionality. Wide range speed control is possible by controlling the dc link voltage. Proposed system is designed, modelled and simulated in a Matlab environment and evaluatory analysis of system is done.

This paper presents a method for the rotor speed and position estimation of permanent magnet synchronous motors in a wide speed range including standstill. The proposed method is based on a modified voltage model at high speeds, and combines the modified voltage model with a high-frequency signal injection technique at low speeds. The fast dynamic response of the voltage model

This paper proposes a method that estimates rotor position by using an unknown input observer over a full speed range. In this method, a trapezoidal back emf is modeled as an unknown input and the proposed unknown input observer estimating line to line back emf in real time makes it possible to detect the rotor position. This observer has high performance even at low speed range because rotor position is calculated independently of the rotor speed without adding any additional circuit or complicated operation process. Simulations have been carried out for the verification of proposed control scheme. MAT LAB/SIMULINK model is used for software simulation.

A new dual stator winding induction machine drive is described in this paper. The proposed induction machine consists of a standard squirrel-cage rotor and a stator with two separate windings wound for a dissimilar number of poles. Each stator winding is fed from an independent variable-frequency variable-voltage inverter. The proposed drive offers such advantages as speed sensorless operation, better reliability, and more flexibility to manipulate the resultant torque-speed curve of the motor. In the proposed drive, zero-speed operation is achieved by independently controlling the two sets of stator currents, hence, maintaining a minimum electrical frequency independent of the mechanical speed. This feature is especially important to minimize the negative impact of the stator resistance influence at low-speed operation and it greatly simplifies the implementation of speed sensorless control schemes. The drive is well suited for either constant volts per hertz or field-oriented (FO) operation. Circulating harmonic currents, common to most dual stator machines, are eliminated by the dissimilar pole number in each stator winding.

This paper addresses control of commutation of switched reluctance (SR) motor without the use of a physical position detector. Rotor position detection schemes for SR motor based on magnetisation characteristics of the motor use normal excitation or applied current /voltage pulses. The resulting schemes are referred to as passive or active methods respectively. The research effort is in realizing an economical sensorless SR rotor position detector that is accurate, reliable and robust to suit a particular application. An effective and reliable means of generating commutation signals of an SR motor based on inductance profile of its stator windings determined using active probing technique is presented. The scheme has been validated online using a 4-phase 8/6 SR motor and an 8-bit processor.

This paper proposes a new position sensorless drive for brushless DC (BLDC) motors. Typical sensorless control methods such as the scheme with the back-EMF detection method show high performance only at a high speed range because the magnitude of the back-EMF is dependent upon the rotor speed. This paper presents a new solution that estimates the rotor position by using an unknown input observer over a full speed range. In the proposed method, a trapezoidal back-EMF is modelled as an unknown input and the proposed unknown input observer estimating a line-to-line back-EMF in real time makes it possible to detect the rotor position. In particular, this observer has high performance at a low speed range in that the information of a rotor position is calculated independently of the rotor speed without an additional circuit or complicated operation process. Simulations and experiments have been carried out for the verification of the proposed control scheme.

The paper presents results of a research on the sensorless drive with PMSM supplied through the sinusoidal filter. The back electromotive force based observer is used to the shaft position estimation. Used in the study, the observer's correction function, contains multi integrators in the path, which improves the position estimation. Otherwise than in a typical implementation of the position observer, the presence of the filter was not taken into account in observer structure, however, it was taken into account in the observer parameters. This type of control allows the use of conventional control system and there is no need to take account the filter in the control circuit. Presented concept has been proven in laboratory.

The paper deals with the problem of speed and position estimation in SRM drive equipped with hysteresis band current controller. Instead of measured current the observer utilize reference current. The voltage is calculated from switching on-time. A speed observer structure which uses estimated back EMF and current of each phase is presented. The shaft position is integrated from estimated speed signal. Observer uses a simplified 1­-dimensional nonlinear equation set instead of 2-dimensional.

It has been well established in the literature that inverter nonlinearity effects afflict saliency-based sensorless drives. The inverter nonlinearity leads to the generation of signals that corrupt the useful position information. The resulting effect differs depending on the injection approach utilized in the drive. Various compensation techniques to overcome this effect have been published in the literature. This paper is concerned with the zero-vector current-derivative technique. The effect of the varying ON-state resistance of the inverter power devices on the position signal is investigated in detail. Knowledge of the source of the corrupting signals facilitates compensation and determines its applicability. Two approaches for inverter nonlinearity compensation are compared. The first approach utilizes a lookup table from offline-processed data, while the second one is a simpler approach based on the current-dependent resistance characteristic of the inverter switching devices. Experimental performance under sensorless condition is shown for both approaches.

A problem of rotor speed and position detection for sensorless PMSM drive was analysed in the paper. The concept based on detecting back EMF, induced in the stator windings, was developed and modified. A general structure of observer, with more complex function of corrector than traditional one was introduced. On the base of this concept the observer with proportional-integral and sliding mode correction was proposed. Simulation as well as experimental results showed good properties of proposed observer structure.

In this paper, a control method is presented for induction motor which offers high efficiency and high dynamics even considering the influences of iron loss. Recently, research to consider the influences of iron loss has been made in the vector control of an induction motor. Vector control method is a quite complex task which demands precise information about the rotor speed and the position of the magnetic flux. The vector control method presented in this paper, estimates both rotor speed and amplitude magnetic flux rotor. However, there are also applications in which even speed sensors should be omitted. In this method, three-phase motor currents and DC link voltage are measured by means of a nonlinear observer and considering the Lyapunov function for current error, motor parameters, rotor shaft and position of flux are estimated. To stabilize the control system, the Lyapunov function for error, is used. Then, using the genetic algorithm, the value of controlling coefficients their and general effects on system's behavior are obtained. The simulation and experimental results confirm the resistant performance and the proper dynamic efficiency of this method. Streszczenie. W artykule przedstawiono algorytm sterowania maszyną indukcyjną, uwzględniający straty w żelazie. Sterowanie opiera się na bezczujnikowym pomiarze prędkości obrotowej, przy pomocy obserwatora. Korzystając z pomiarów prądów fazowych i napięcia DC-link, z funkcji Lyapunov'a wyznaczana jest prędkość i strumień wirnika. Implementacja algorytmu genetycznego pozwoliła na ocenę wpływu współczynników regulacji na odpowiedź układu. Przedstawiono wyniki symulacyjne i eksperymentalne. (Sterowanie maszyną indukcyjną z bezczujnikowym pomiarem prędkości obrotowej -nieliniowy obserwator strumienia i prędkości z estymacją parametrów i uwzględnieniem strat w żelazie).

Stator flux oriented vector control of induction motor (IM) drives for speed sensorless control has several advantages. But, theapplication of a pure integrator for the flux estimation is difficult due to the presence of measurement noise and dc offset. To overcome these problems, a programmable cascaded low pass filters (PCLPF) has been used in some text. In this paper it is shown that some problems still exist and some new problems is made by this approach. In order to solve these problems, a novel compensation method is proposed. In this scheme the dc offset is detected and subtracted from the estimated flux in d and q axes.
The simulation results show that it works well in the low speed region as well as in the transient state. And the oscillation of the torque and the estimated flux are reduced notably when the torque reference changes rapidly.

A robust high speed algorithm, RHSA, applied in the field oriented vector control strategy, is presented in this paper for the PMSM sensorless control loop. The present algorithm, RHSA, is formed for online generating the direct and quadrature reference stator current. Based on the fuzzy logic controller and the field weakening principle, the RHSA is constructing. The sliding mode, based on Lyapunouv stability criterion, is used for the online speed estimation. The Robustness of the global control scheme is verified through computer simulation using matlab/Simulink software.

A new control structure is presented for use at the sensorless control of speed for low speed range. That method uses an observer for position estimation. Such structure does not require the calculation of the speed value from the estimated back EMF, thus such drive can work even in a case of non-sinusoidal shape of estimated back EMF. Such structure is especially recommended for speed in a range single revolutions per second (excluding standstill). Proposed structure is similar to the model following control, but the reference model is trying to track the motor operating point.

Rotor angle calculation using flux estimation is a straightforward approach to sensorless control of synchronous reluctance motor (SYRM), but the dc offset can cause an increasing error in pure integrator used in this estimator. In this paper to control motor at low speed region a modified programmable cascaded low pass filters (MPCPLF) is proposed. MPCLPF is suggested because programmable cascade low pass filters (PCLPF), which has previously been applied to induction motors, has some problems in low speed area. In addition PCLPF is affected by the parameter fluctuation. To overcome the problem an online parameter identification method based on block pulse function also is proposed. In this method the parameter identification is not affected by position estimation accuracy. The experimental system includes a PC-based control with real time Linux as operating system. And to acquire data form sensors and to send commands to the system an ALTERA complex programmable logic device (CPLD) is used. The experimental results show the proposed method performs well and speed estimation, angles estimation and parameter identification are correct. Also it is shown sensorless vector control is achieved at low speed as well as high speed using proposed method

Efficient and precise sensorless speed control of a permanent-magnet synchronous motor (PMSM) requires accurate knowledge of rotor flux, position, and speed. In the literature, many sensorless schemes have been presented, in which the accurate estimation of rotor flux magnitude, position, and speed is guaranteed by detecting the back electromotive force (EMF). However, these schemes show great sensitivity to stator resistance mismatch and system noise, particularly, during low-speed operation. In this paper, an indirect-rotor-field-oriented-control scheme for sensorless speed control of a PMSM is proposed. The rotor-flux position is estimated by direct integration of the estimated rotor speed to reduce the effect of the system noise. The stator resistance and the rotor-flux speed and magnitude are estimated adaptively using stable model reference adaptive system estimators.

– The field oriented based vector control (FOC) and the direct torque (DTC) are well used control strategies in modern AC systems these days. They can create a decupled flux and torque control and achieve good performance for AC motor drives. However, both of them have a number of limits and drawbacks, such as the dependence of machine parameters of the vector control and the high flux and torque ripples of DTC. This work present a hybrid control strategy for induction motor bases on combining the principles of the two techniques, in order to benefit from their advantages and limit their disadvantages and gain high performance. Besides, this work aims to design a sliding mode observers for speed/flux as sensorless algorithm to improve the reliability and decrease the cost control system. Different results of this combined strategy will be investigated by numerical simulation using Matlab/Simulink.

This paper deals with the speed sensorless vector control of an induction motor in a special case where the output voltage of the pulsewidth-modulated inverter is filtered by an inductance-capacitance (LC) filter. The system states are estimated by means of an adaptive full-order observer, and no additional voltage, current, or speed measurements are needed. The rotor speed adaptation is based

... H. Abu-Rub is with Texas A&M University at Qatar, Doha 23874, Qatar (e-mail: haitham.abu-rub@ qatar.tamu.edu). ... 2008. [10] KM Al-Hussain, “Dynamic stability of two rigid rotors connected by a flexible coupling with angular misalignment,” J. Sound Vib., vol. 266, no. 2, pp. ...

In this paper, a sensorless speed control for interior permanent magnet synchronous motors (IPMSM) is designed by combining a robust backstepping controller with integral actions and an adaptive interconnected observer. The IPMSM control design generally requires rotor position measurement. Then, to eliminate this sensor, an adaptive interconnected observer is designed to estimate the rotor position and the speed. Moreover, a robust nonlinear control based on the backstepping algorithm is designed where an integral action is introduced in order to improve the robust properties of the controller. The stability of the closed-loop system with the observercontroller scheme is analyzed and sufficient conditions are given to prove the practical stability. Simulation results are shown to illustrate the performance of the proposed scheme under parametric uncertainties and low speed. Furthermore, the proposed integral backstepping control is compared with the classical backstepping controller.

This paper presents a comparative study of sliding mode, artificial neural network and model reference adaptive speed observers for a speed sensorless permanent magnet synchronous generator (PMSG) in wind energy conversion system (WECS). Wind velocity and position sensorless operating methods for wind generation system using observer are proposed only by measuring phase voltages and currents. Maximum wind energy extraction is achieved by running the wind turbine generator in variable-speed mode. In addition the three speed observers are compared to verify the robustness against parameter variations.

The paper presents a method for estimating the shaft position of a synchronous motor with permanent magnets (PMSM) for the zero and very low speed range. The method is based on the analysis of the high frequency currents, which are induced by the additional test voltage in a stationary coordinate system associated with the stator. Although this method involves the identification of currents hodograph, the method does not need to calculate the current ellipse position. Presented method involves a comparison of obtained shape to the reference pattern using probabilistic neural network (PNN). The method can achieve satisfactory accuracy in a case the high asymmetry of the inductance, as well as in the case of small values of the inductance asymmetry ratio, also in the case of a high level of noise.

Based on Simulink/Modelsim co-simulation technology, the design of a sensorless control IP (Intellectual Property) for PMSM (Permanent Magnet Synchronous Motor) drive is presented in this paper. Firstly, a mathematical model for PMSM is derived and the vector control is adopted. Secondly, a rotor flux position is estimated by using a sliding mode observer (SMO). These estimated values are feed-backed to the current loop for vector control and to the speed loop for speed control. Thirdly, the Very-High-Speed IC Hardware Description Language (VHDL) is adopted to describe the behavior of the sensorless speed control IP which includes the circuits of space vector pulse width modulation (SVPWM), coordinate transformation, SMO, fuzzy controller, etc. Fourthly, the simulation work is performed by MATLAB/Simulink and ModelSim co-simulation mode, provided by Electronic Design Automation (EDA) Simulator Link. The PMSM, inverter and speed command are performed in Simulink and the sensorless sp...

This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear input-output mapping. Based on this nonlinear mapping, the wind speed is estimated from the measured generator electrical output power while taking into account the power losses in the WTG and the dynamics of the WTG shaft system. The estimated wind speed is then used to determine the optimal DFIG rotor speed command for maximum wind power extraction. The DFIG speed controller is suitably designed to effectively damp the low-frequency torsional oscillations. The resulting WTG system delivers maximum electrical power to the grid with high efficiency and high reliability without mechanical anemometers. The validity of the proposed control algorithm is verified by simulation studies on a 3.6 MW WTG system. In addition, the effectiveness of the proposed wind speed estimation algorithm is demonstrated by experimental studies on a small emulational WTG system.

This paper presents a modified model reference adaptive system (MRAS) speed estimator for induction motors (IM) based on regulation of the instantaneous rotor magnetizing reactive power, which does not use integration or stator resistance in the reference model. The proposed modifications allow analytical tuning and facilitate implementation of the estimator in a digital signal processor (DSP). The detuning of the estimator with respect to the rotor time constant is exploited as a source of information in a novel parallel identification mechanism for this parameter. The rotor time constant error is obtained by l e T T , -electromagnetic and load torque B J m , -motor-load inertia and friction coefficient Page 2 of 20

This paper proposes a sensorless vector control scheme for general-purpose induction motor drives using the current error space phasor-based hysteresis controller. In this paper, a new technique for sensorless operation is developed to estimate rotor voltage and hence rotor flux position using the stator current error during zero-voltage space vectors. It gives a comparable performance with the vector control drive using sensors especially at a very low speed of operation (less than 1 Hz). Since no voltage sensing is made, the dead-time effect and loss of accuracy in voltage sensing at low speed are avoided here, with the inherent advantages of the current error space phasor-based hysteresis controller. However, appropriate device on-state drops are compensated to achieve a steady-state operation up to less than 1 Hz. Moreover, using a parabolic boundary for current error, the switching frequency of the inverter can be maintained constant for the entire operating speed range. Simple σL s estimation is proposed, and the parameter sensitivity of the control scheme to changes in stator resistance, R s is also investigated in this paper. Extensive experimental results are shown at speeds less than 1 Hz to verify the proposed concept. The same control scheme is further extended from less than 1 Hz to rated 50 Hz six-step operation of the inverter. Here, the magnetic saturation is ignored in the control scheme.

Matrix converters are becoming a real alternative to traditional topologies for many ac-ac power conversion applications. One of the less well-known advantages is the potential for reduced waveform distortion that arise from device characteristics and commutation delays. This paper describes the origin of distortion effects for a matrix converter with current sign-based commutation and gives a novel approach to the method that can, in principle, eliminate the distorting effects to give a power converter having excellent linear behavior. The effectiveness of compensation techniques are illustrated for both an open-loop matrix converter driving a passive load and a matrix converter as part of a vector-controlled drive.

In this paper a sensorless closed-loop speed control for the synchronous reluctance motor is presented. The sensorless control is based on the torque vector control algorithm. It has been implemented using a high-speed digital processor DSP96002. Experimental results for a 120 W axially-laminated synchronous reluctance motor are presented and compared with operation with a speed sensor and simulations. A base speed range of 400-1500 rpm has been achieved. The top speed was extended to 2750 rpm using flux-weakening. The drive can be applied a full-load step-change within this speed range without losing synchronism.