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© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works This article presents two algorithms to control the speed of doubly-fed induction motors. The controllers are designed using the complex-valued sliding mode methodology to track either the rotor or the stator current. An outer loop controls the mechanical speed. The control schemes are validated experimentally and compared in a laboratory setup.

Routh's treatise [1] was a landmark in the analysis of the stability of dynamic systems and became a core foundation of control theory. The remarkable simplicity of the result was in stark contrast to the challenge of the proof. Many researchers devoted much effort to extend the result to singular cases, with some of the earlier techniques shown to be inadequate [2]. Together with the extensions to singular cases, shorter proofs were also proposed. The proof of [3] is noteworthy, which followed the root locus arguments of [4]. A key feature of the proof is a continuity argument used in an earlier derivation [5]. In [6], the more conventional approach using Cauchy?s principle of the argument is followed. A relatively simple proof is proposed, considering the extension to complex polynomials and singular cases.

This paper considers a hybrid electric propulsion architecture where most of the electric power is transmitted from the generator to the motors without conversion. Doubly fed induction machines are...

A multiple-reference complex-based controller is proposed for three-phase power converters feeding nonlinear and unbalanced loads. The control scheme incorporates a stable multiple-complex coefficient filter with bandwidths that are set arbitrarily and independently for every harmonic under consideration. The multiple-reference complex-based control scheme is applied to an uninterruptible power supply system with a voltage source converter. Each harmonic is controlled using a standard complex proportional-resonant controller that is designed for stability and robustness using the Nyquist criterion. Similar stability and robustness properties follow for the overall system due to the frequency-domain properties of the filter and of the controllers. The proposed methodology is validated in simulation and experimental tests.

The paper considers the problem of sub-synchronous resonances (SSR) in doubly fed induction generators connected to the grid through series-compensated lines. The existence of oscillations is observed on a laboratory test-bed in various conditions, with instabilities developing in the worst-case scenario. Despite the limitations of a small-scale test-bed, the ability to investigate problems and solutions in ways that would not be possible on a full-scale system is very valuable. In particular, the paper demonstrates the significant effect of the choice of dq reference frame on the severity of SSR. Stator-aligned algorithms are found to be significantly more resonant than grid-oriented algorithms, as evidenced in experiments as well as using an analysis method proposed in the paper. From this observation, an algorithm is proposed to emulate a grid-alignment using stator voltages and currents, but without measurements of the grid and series-capacitor voltages. Two control laws are then presented to regulate the active and reactive powers generated, resulting in well-damped transient responses. SSR oscillations are found to be eliminated in experime, as well as simulations of a full-scale system and using a frequency response analysis of the closed-loop system. The effectiveness of the proposed control schemes is verified through experiments for different compensation levels and varying speeds. Within the assumptions made in the design, the proposed controllers are global.

The paper presents three algorithms to synthesize a dynamic controller for a doubly-fed induction generator (DFIG). In each case, the pole placement approach is used to compute the parameters of a feedback controller that regulates the active and reactive powers produced using the rotor voltages. Due to the special structure of the DFIG's model, the analysis and design of the feedback control loop are simplified by transforming its representation into an equivalent system with complex coefficients and half the number of states. This approach yields analytic solutions of the problem with remarkable simplicity. The complex framework facilitates the direct placement of the DFIG system poles in the left half-plane, which ensures stability and performance of the closed-loop system. Additionally, this framework can be used to evaluate the robustness properties of the closed-loop systems. The ability of the synthesized controllers to provide a desirable dynamic and steady-state response is investigated through experiments on a laboratory testbed.

A new controller for a grid-connected inverter with an LCL filter is proposed in this paper. The system is described by its complex representation, and the controller is designed using the complex root locus method. The complex representation allows a considerable reduction in the order of the system, simplifying the design task and making it possible to use advanced techniques, such as the complex root locus. The new complex controller adds an extra degree of freedom that makes it possible to move the poles of the systems and to improve the stability and speed of response compared with the conventional controls. This paper includes a detailed discussion of the effect of the gains of the controller on the root locus. The proposal is validated with simulation and experimental results.

International audience; This paper presents a new state-space model (SSM) to represent the four types of currents flowing through a Modular Multilevel Converter (MMC). In line with the converter topology, the model itself is modular. In other words, its configuration adapts itself to the number of AC phases, to the active or passive nature of the AC-side grid, to the connection between the AC and DC neutral points, and to the number of submodules. The model describes the influence of the MMC arm voltages on the currents using an average behavior of the submodules. Simulations performed using a software dedicated to electrical engineering systems demonstrate the value and the accuracy of the proposed model.

This paper presents a modeling of the modular multilevel converter (MMC) which is modular, inline with its topology. The modeling of the MMC is made of two parts, a low-level part which deals with the description of the sub-modules (SM) connected to the arms of the MMC and a high-level part which represents the behavior of the MMC with its interfaces, it is this high-level part which is studied here. Two state-space models are developed, they describe the influence of the arm voltages of the MMC on the different types of currents flowing within the converter. These models are scalable to the number of phases and to the number of sub-modules composing the MMC. The first model is derived in the stationnary m-phase reference frame while a reduction of order is performed to obtain the second one which is developed in the rotating frame, making the order of the latter independent of the number of phases and the number of sub-modules. Simulations show the value of these models in terms of simulation time and accuracy., Cet article présente une modélisation du convertisseur modulaire multiniveaux (MMC) qui se veut modulaire à l'image de sa topologie. La modélisation du MMC est composée de deux parties, une partie bas-niveau qui traite de la description des sous-modules (SM) qui composent le MMC et une partie haut-niveau qui représente le comportement du MMC avec ses interfaces, c'est cette partie haut-niveau qui est traitée ici. Deux modèles dans l'espace d'état sont développés, ils décrivent l'influence des tensions propres aux bras du MMC sur les différents types de courants qui le traversent. Ces modèles sont capables de s'adapter au nombre de phases et au nombre de sous-modules composant le MMC. Le premier modèle est réalisé dans le repère fixe m-phasé tandis qu'une réduction d'ordre est opérée pour obtenir le second qui est rattaché au repère tournant, rendant alors l'ordre de ce dernier indépendant du nombre de phases et du nombre de sous-modules. Des simulations mettent en évidence l'intérêt de ces modèles sur le plan du temps de simulation et de la précision obtenue.

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works In this work, a complex-valued controller for a three-phase VSC with an LC output filter is proposed. The system is first transformed into its complex representation with the consequent order reduction and simpler analysis. The proposed complex controller places all the poles at desirable locations in the complex plane. Unlike classical controllers with an inner current-control loop and outer voltage-control loop, the proposed controller considers the complete dynamics of the system, thus ensuring the closed-loop stability. Furthermore, the complex representation facilitates the pole placement in the complex plane compared to the real domain. The performance of the proposed controller is validated through simulations and experiments.

This brief proposes an optimization formulation of the control problem for power electronic converters. A benefit of the approach is a systematic method for the control of high-switch-count static converters. In the case of the three-phase, four-leg, two-level inverter, the framework provides a characterization of all the possible solutions that yield a maximal extension of the inverter linearity range. The method makes it possible to recover well-known modulation strategies as well as to discover some new ones having different properties and distinct advantages. The characteristics resulting from different design choices are evaluated in simulations, with consideration being given to the linearity range, total harmonic distortion, and switching losses. Key principles of extension of the proposed method to multilevel, multileg converters are given, as well as motivations for a field-programmable gate array-based hardware implementation enabling real-time pulsewidth modulation control.

An elegant way to exploit redundancies available in multilevel converters is through a constrained optimization formulation. An interesting connection can be made with the so-called control allocation problems defined in over-actuated constrained systems. Redundancies and constraints are taken into account to achieve the best performance. In this paper, we introduce the first result of an investigation of control allocation methods for multilevel conversion. The method is dedicated to the flying-capacitor inverter with focus on the active balancing of capacitor voltages to ensure admissible blocking voltages for the switches. A linear program is formulated and solved by using the well-established simplex algorithm. Fast variations of the DC-bus voltage were applied in simulations. Disturbances are well rejected, resulting in an increased bandwidth and a safe switching operation for the semiconductors.

International audience; This paper presents a control algorithm for the parallel interconnection of heterogeneous power converters. A single resistive load is assumed to be fed by an arbitrary number of buck converters via a common DC bus. The approach is based on control allocation theory and a constrained quadratic optimization algorithm. The strategy achieves a fast voltage response with an optimal current distribution among the converters, while taking into account the current limits, the dynamic response, and the efficiency of the individual converters. An interesting by-product of the approach is the ability to put converters in and out of service through trivial adjustments of the code. The benefits of the approach are assessed through simulations and an experimental evaluation.

Une maniere elegante d'exploiter efficacement les redondances de commande disponibles pour les convertisseurs statiques multi-niveaux est de formuler des problemes d'optimisation contraints. Ces problemes sont similaires aux problemes dits d'allocation de commandes rencontres pour les systemes mecaniques sur-actionnes. Les redondances et les contraintes sont prises en compte pour obtenir les meilleures performances. Dans ce papier, nous presentons un des premiers resultats de l'etude de methodes de commande par allocation pour la conversion statique multi-niveaux. Nous proposons une nouvelle methode pour l'onduleur a condensateurs flottants avec une attention particuliere portee sur l'equilibrage actif des tensions des condensateurs afin de maintenir des tensions de commutation admissibles pour les interrupteurs. Nous formulons un probleme d'optimisation lineaire dont la resolution repose sur le celebre algorithme du simplexe. En simulation, nous faisons subir de fortes variations de la tension continue d'entree. Grâce a notre methode, ces perturbations sont rapidement rejetees, garantissant une meilleure securite des interrupteurs de puissance et une bande passante elevee.

The Special Issue presents results of current research on adaptive methods designed for periodic signals with unknown frequency. The first group of papers presents new methods for parameter estimation, while the second group focuses on practical applications involving active noise and vibration control problems. These papers are compiled in a special virtual issue of the journal at the journal homepage. To access all of the papers please follow the following link http://onlinelibrary.wiley.com/journal/10.1002/ISSN1099-1115/homepage/virtual_issue_-_recent_advances_in_adaptive_methods_for_frequency_estimation_wit.htm. Copyright © 2016 John Wiley & Sons, Ltd.

The Convergent Aeronautics Solutions (CAS) High Voltage-Hybrid Electric Propulsion (HVHEP) task was formulated to support the move into future hybrid-electric aircraft. The goal of this project is to develop a new AC power architecture to support the needs of higher efficiency and lower emissions. This proposed architecture will adopt the use of the doubly-fed induction machine (DFIM) for propulsor drive motor application.The Convergent Aeronautics Solutions (CAS) High Voltage-Hybrid Electric Propulsion (HVHEP) task was formulated to support the move into future hybrid-electric aircraft. The goal of this project is to develop a new AC power architecture to support the needs of higher efficiency and lower emissions. This proposed architecture will adopt the use of the doubly-fed induction machine (DFIM) for propulsor drive motor application. DFIMs are attractive for several reasons, including but not limited to the ability to self-start, ability to operate sub- and super-synchronously, and requiring only fractionally rated power converters on a per-unit basis depending on the required range of operation. The focus of this paper is based specifically on the presentation and analysis of a novel strategy which allows for independent operation of each of the aforementioned doubly-fed induction motors. This strategy includes synchronization, soft-start, and closed loop speed control of each motor as a means of controlling output thrust; be it concurrently or differentially. The demonstration of this strategy has recently been proven out on a low power test bed using fractional horsepower machines. Simulation and hardware test results are presented in the paper.

This paper develops a systematic comparison of two nonlinear models of induction machines in magnetic saturation using stator and rotor currents as state variables. One of the models accounts for dynamic cross-saturation effects, whereas the other neglects them. Analytic derivations yield an explicit description of the difference between the models showing that differences can only be observed through transient responses in the saturated region. To refine the comparison, and exclude conditions in the linear magnetic region, the dynamics of self-excited induction generators around stable operating points is analyzed. Unexpected and interesting features of the models are revealed through their linearization in the reference frame aligned with the stator voltage vector, followed by computation of the transfer functions from perturbations to state deviations. The analysis predicts a slower exponential convergence of the simplified model compared to the full model, despite very close responses in the initial period. The comparison is validated via thorough experiments and simulations. This paper provides experimental evidence of the higher accuracy of the full model for transients deep into the saturated region. For realistic operating conditions, the difference is found to be rather small, and often comparable to the steady-state error caused by inaccuracies in the parameters.

Spontaneous self-excitation in induction generators is a fascinating phenomenon triggered by the instability of a zero equilibrium state. Prediction of this condition for various values of free parameters requires many computations of the eigenvalues of a 6 × 6 matrix over a large space. The technical note uses a novel approach to stability using a transformation of the state-space system and an extension of the Hurwitz test to polynomials with complex coefficients. The analytic formulas that are obtained give the values of the minimum load resistance, the range of capacitor values, and the range of speeds for which spontaneous self-excitation appears. The technical note concludes with an illustration of the results on an example.

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. A large class of three-phase electrical power systems possess symmetry conditions that make it possible to describe their behavior using single-input single-output transfer functions with complex coefficients. In such cases, an extended root locus method can be used to design control laws, even though the actual systems are multi-input multi-output. In this paper, the symmetric conditions for a large class of power systems are analyzed. Then, the root locus method is revisited for systems with complex coeffcients and used for the analysis and control design of power systems. To demonstrate the benefits of the approach, this paper includes two examples: 1) a doubly fed induction machine and 2) a three-phase LCL inverter.

International audience; In this paper, a new carrier-based pulse-width modulation (PWM) technique for a voltage source inverter (VSI) is presented. The new modulation law is obtained using a particular configuration of a control allocation technique based on a per-switching-state formulation of the 4-leg 2-level inverter. The resulting modulation law is equivalent to the injection of the opposite of the median reference voltage as a zero-sequence voltage. This particular solution produces a smooth transition from a continuous modulation mode at low modulation depth to a dis-continuous modulation mode at high modulation depth. This hybrid solution makes it possible to focus on the THD for low output voltages and reduce losses for higher voltages.

This paper investigates the control of power generation using two-phase squirrel-cage induction machines, where the load is connected to one stator winding and the load voltage is controlled through the other winding. The concept can be applied to three-phase machines as well. A state-space model of the machine is used to identify suitable operating regions. Then, two types of control algorithms are proposed: The first type regulates the frequency and the magnitude of the generated voltage and is suitable for stand-alone operation. The second type also regulates the phase of the voltages, enabling grid synchronization. Experimental results are presented for each of the control algorithms. The closed-loop systems are found able to track the desired reference and to reject disturbances caused by significant changes in load and speed.

The paper presents a new procedure to identify at the same time the electrical parameters of a permanent magnet stepper motor (PMSM) and the initial offset of an incremental encoder. The model considers effects due to the permanent magnet and to variable reluctance, and the resulting theory is applicable to cases where both or only one of these terms is present. The standard DQ model of PMSM's assumes that the permanent magnet is lined up with a winding when the position is zero. When an incremental encoder is used, an initialization procedure is required to zero the initial offset. In contrast, this paper computes a transformed model that accounts for the initial offset. then develops a least-squares identification algorithm that estimates the machine's electrical parameters together with the offset angle. Experiments show that the estimation procedure and a closed-control method using the estimated offset perform similarly compared to when the offset is reset to zero using an initilization procedure.

In self-excited induction machines, a power generating mode of operation can often be attained only by precharging at least one of the capacitors connected to the windings. The paper shows how a carefully derived state-space model with nonlinear magnetic characteristics enables the assessment of all possible operating regimes including their stability properties. In particular, the analysis reveals the possible existence of an unstable operating regime, which creates a barrier that must be overcome through precharged capacitors. In such case, the analytical results of the paper yield a simple formula that predicts the voltage needed to trigger self-excitation. Close to the boundary, voltages can be generated for extended periods of time before growing to a stable operating regime, or collapsing to zero. Experimental results validate the results of the paper on the transient properties of self-excited induction generators.

Robots are often run with permanent magnet synchronous motors (PMSM) with a high ratio gearbox. Both parts can produce parasitic oscillations (ripples), which let the robot shake at tool center point. The gearbox ripple problem is more complicated to be solved with control theory because only motor side sensors should be used. Due to the internal model principle gearbox side information is necessary to solve the problem. The first algorithm uses an observer to get gearbox side information where the second algorithm uses a gearbox side rate sensor. The algorithms are tested with a nonlinear SISO problem and with a nonlinear MIMO system. In both cases the ripples are canceled with an adaptive controller which estimates the phase and magnitude of the ripple. This adaptive controller is designed separately and is added to the existing basis controller. The algorithms are tested in simulation and on a testbed, which is an industrial application.

A method is proposed to estimate the rotor time constant TR of an induction motor without measurements of the rotor speed/position. The method consists of solving for the roots of a polynomial equation in TR whose coefficients depend only on the stator currents, stator voltages, and their derivatives. Experimental results are presented

Indirect field-oriented control of an induction machine requires knowledge of the rotor time constant to estimate the rotor flux linkages. Here, an online method is presented for estimating the rotor time constant and the stator resistance, both of which vary during operation of the machine due to ohmic heating. The method uses measurements of the stator voltages, stator currents, and their derivatives (first derivative of the voltages and both the first and second derivatives of the currents). The problem is formulated as finding those parameter values that best fit (in a least-squares sense) the model of the induction motor to the measured output data of the motor. This method guarantees that the parameter values are found in a finite number of steps. Experimental results of an online implementation are presented

The complexity and strong nonlinearity of the model of a self-excited induction generator hinder the systematic design of a voltage regulation system. Using a special reference frame aligned with the stator voltage vector, the paper succeeds in developing a control-oriented linearized model that relates small deviations of the capacitance, load admittance, and angular velocity, to corresponding deviations of the voltage amplitude. Transfer functions are also computed based on the linear model. A stability analysis predicts rapidly decaying oscillatory transients combined with a primary component with slower exponential decay. Simulated transient responses of the full and linearized models demonstrate the validity of the approximation and are in good agreement with experiments.\ud

This note considers a differential-algebraic approach to estimating the speed of an induction motor from the measured terminal voltages and currents. In particular, it is shown that the induction motor speed /spl omega/ satisfies both a second- and a third-order polynomial equation whose coefficients depend on the stator voltages, stator currents, and their derivatives. It is shown that as long as the stator electrical frequency is nonzero, the speed is uniquely determined by these polynomials. The speed so determined is then used to stabilize a dynamic (Luenberger type) observer to obtain a smoother speed estimate. With full knowledge of the machine parameters and filtering of the sensor noise, simulations indicate that this estimator has the potential to provide low speed (including zero speed) control of an induction motor under full rated load.

A nonlinear least-squares method is presented for the identification of the induction motor parameters. A major difficulty with the induction motor is that the rotor state variables are not available measurements so that the system identification model cannot be made linear in the parameters without overparametrizing the model. Previous work in the literature has avoided this issue by making simplifying assumptions such as a "slowly varying speed." Here, no such simplifying assumptions are made. The problem is formulated as a nonlinear least-squares identification problem and uses elimination theory (resultants) to compute the parameter vector that minimizes the residual error. The only requirement is that the system must be sufficiently excited. The method is suitable for online operation to continuously update the parameter values. Experimental results are presented.

International audience; The paper presents a new sensorless parameter identification method for permanent magnet stepper motors. Current sensors are assumed available, but mechanical sensors are not. Data is obtained with open-loop commands at multiple speeds. A new frame is proposed that presents advantages similar to the d-q frame, but without the need for a position sensor. The method exploits derived linear parameterizations and least-squares algorithms. In some cases, overparameterization is resolved using elimination theory. The parameters identified using the new procedure are found to be very close to those obtained with sensors. The approach is potentially applicable to other types of synchronous motors.

In this note a globally stable methodology is proposed to estimate the frequency, phase, and amplitude of a sinusoidal signal affected by additive structured and bounded unstructured disturbances. The structured disturbances belong to the class of time-polynomial signals incorporating both bias and drift phenomena. Stability and robustness results are given by resorting to Input-to-State stability arguments. Simulation comparative results show the effectiveness of the proposed technique.

This paper proposes an active noise control algorithm for periodic disturbances of unknown frequency. The algorithm is appropriate for the feedback case in which a single error microphone is used. The previously-proposed algorithm (Bodson et al. (1997)) for the rejection of sinusoidal noise sources is extended for the cancellation of multiple harmonics. Unlike many other approaches, the estimates of the frequencies of the separate harmonics are tied together within the algorithm to account for the integer multiplicative relations between them. The dynamic behavior of the closed-loop system is analyzed using an approximation that is shown, in simulations, to provide an accurate representation of the system's behavior. Experimental results on an active noise control testbed demonstrate the success of the method in a practical environment.

This paper considers a method proposed by Chaplin and Smith for the cancellation of repetitive vibrations. Direct implementation of the concepts of the patent is not straightforward because of the lack of precise information regarding certain components, and because of the absence of guidelines for the design of a system with satisfactory stability and performance properties. This paper proposes a specific algorithm based on the concepts of the patent, and provides an approximate analysis which is found useful to obtain a closed-loop system with predictable dynamic characteristics. Simulations demonstrate the validity of the approximation and the success of the design. A tendency of the algorithm for convergence toward undesirable operating states is identified, and an improved version is derived. The algorithm is also compared to another algorithm proposed-for the same purposes.

Applications were found recently where the analy- sis of dynamic systems with a special structure could be simp li- fied considerably by transforming them into equivalent syst ems having complex coefficients and half the number of poles. The design of controllers for such systems can be simplified in th e complex representation, but requires techniques suitable for systems with complex coefficients. In the paper, the extensi on of the classical root locus method to systems with complex coefficients is presented. The results are applied with some advantages to a three-phase controlled rectifier.

In this brief, a new control scheme is presented for the doubly fed induction machine (DFIM). The proposed control algorithm offers the advantages of proven stability and remarkable simplicity. In contrast to the classical vector control method, where the DFIM is represented in a stator- flux-oriented frame, a model wit h orientation of the stator voltage is adopted. This approach allows the decomposition of the active and reactive powers on the stator side and their regulation on the rotor side. A main contribution of this brief is the use of the Hurwitz test for polynomials with complex coefficients that has had little prior application in control theory. This results in a proof that a proportional-integral (PI) control regulating the stator currents ensures global stability for a feedback-linearized DFIM. The specific condition that the PI gains must satisfy is derived as a simple inequality. The PI controller has a particular structure that directly relates the d -component of the rotor voltages to the q -component of the stator currents and vice versa. The feedback linearization stage only uses the direct measurement of the rotor and stator currents and is thus easily implementable. Furthermore, it is also shown that the PI controller (without the feedback linearization terms) is also stable for a large range of control gains and does not require the knowledge of the machine parameters. Finally, the control system is validated in simulations and in experiments.

Two-dimensional linear, time-invariant simulation results of a magnetoresistive (MR) head readback response for Position Error Signal (PES) generation are compared with experimental data. Split-burst amplitude and null patterns are considered for the off-track study. Micro-track profiling results for use in the simulations are also presented. The simulations capture the on-track response of the MR head, although the predicted off-track response is degraded. The simulated PES predicts more non-linearity with off-track displacement than the experimental data indicates. The results suggest that more advanced simulation techniques are required for servo channel design and prediction.

In this paper, we consider the problem of estimating the angular velocity of an induction motor using encoder measurements. Two methods are compared. In the first method, the speed is found by calculating the backward difference of the position measurement and low-pass filtering the result. In the second method, the velocity is estimated using a nonlinear observer constructed using the known dynamic model of the induction motor. The performance of the two methods is evaluated in the context of their use for velocity feedback in a high-performance field-oriented control law. Experimental results demonstrate that the speed observer leads to a smoother operation of the motor in closed-loop. With the estimator based on differentiation, either the delay imposed by the low-pass filter is too large to maintain high bandwidth feedback, or the fluctuations in the estimated speed are so large that much more energy ends up being dissipated to achieve the same control task. >

Advances in sensors and avionics computation power suggest real-time structural load measurements could be used in flight control systems for improved safety and performance. A conventional transport flight control system determines the moments necessary to meet the pilot's command, while rejecting disturbances and maintaining stability of the aircraft. Control allocation is the problem of converting these desired moments into control effector commands. In this paper, a framework is proposed to incorporate real-time structural load feedback and structural load constraints in the control allocator. Constrained optimal control allocation can be used to achieve desired moments without exceeding specified limits on monitored load points. Minimization of structural loads by the control allocator is used to alleviate gust loads. The framework to incorporate structural loads in the flight control system and an optimal control allocation algorithm will be described and then demonstrated on a nonlinear simulation of a generic transport aircraft with flight dynamics and static structural loads.

International audience; The paper presents a new sensorless parameter identification method for permanent magnet stepper motors. Current sensors are assumed available, but position and velocity sensors are not. Data is obtained with open-loop voltage com- mands at multiple speeds. A new reference frame is proposed that presents advantages similar to the standard d − q frame, but without the need for a position sensor. The method exploits carefully derived linear parameterizations and a least-squares algorithm. In one case, overparameterization is resolved using elimination theory. Overall, the parameters identified using the new procedure are found to be very close to those obtained with position sensors. The approach is potentially applicable to other types of synchronous motors as well.

An example is presented of an adaptive system that becomes unstable when a multitone reference input is applied, although it is stable when the spectral components are applied separately. It is further shown that another scheme, based on an input error instead of an output error in the adaptation, does not exhibit the same instability mechanism. The technique of averaging is used to analyze this phenomenon. The equilibrium points of the averaged system, called the tuned values, are investigated. Results are given on the number of tuned values, their locations, and their stability. The analysis is not only valid for a specific plant, but for a large class of systems. >

In this work, a robust method to estimate sinusoidal signals of unknown frequency, amplitude and phase is described. The stability properties of the devised estimation method under perturbed condition are studied by Input-to-State Stability (ISS) analysis. Compared to averaging approaches, the ISS-Lyapunov theory allows to study the stability for any value of adaptation parameters.

Three configurations of a unique single-phase power generation system based on inexpensive single-phase induction motors are proposed in this paper. All of these configurations are well suited for residential or equivalent small-scale grid- tied power generation schemes because of their reduced cost, smaller footprint and minimum or no required maintenance. The wind power generation schemes presented in this paper could be used in stand-alone or grid-parallel mode without using any energy storage. Various characteristics of these configurations are summarized in this paper with necessary simulation and experimental results. In addition, an analytical model of the single-phase induction generator is presented to identify its operating characteristics.

Permanent magnet synchronous motors (PMSMs) produce a parasitic oscillating torque due to several reasons. This contribution cancels the oscillating torque with adaptive control algorithms. Therefore a mathematical model of the PMSM is necessary. A model with nonlinear dynamics and a Fourier approach for the ripples is used as a mathematical description. Through comparisons between measured data and simulated data it is shown that the model assumptions are valid. The adaptive algorithm is implemented as an add-on controller to the already existing control system which consists of a feedforward part and a basis controller. The challenge is that the closed loop system has a resonant frequency and the algorithm should have the same performance for all frequencies. Experimental results show the performance and convergence of the adaptive algorithm at constant and non constant velocity.

The problem of controlling a shunt DC motor is considered. Recent methods for nonlinear control are compared, including feedback linearization, generalized controller canonical forms, and input-output linearization. Connections between the approaches, as well as their respective advantages are discussed in detail. >

Conventional aircraft generally employ mixing algorithms or lookup tables to determine control surface deflections needed to achieve moments commanded by the flight control system. Control allocation is the problem of converting desired moments into control effector commands. Next generation aircraft may have many multipurpose, redundant control surfaces, adding considerable complexity to the control allocation problem. These issues can be addressed with optimal control allocation. Most optimal control allocation algorithms have control surface position and rate constraints. However, these constraints are insufficient to ensure that the aircraft's structural load limits will not be exceeded by commanded surface deflections. In this paper, a framework is proposed to enable a flight control system with optimal control allocation to incorporate real-time structural load feedback and structural load constraints. A proof of concept simulation that demonstrates the framework in a simulation of a generic transport aircraft is presented.