L. Salvatore

Università degli Studi di Bari Aldo Moro, Bari, Apulia, Italy

Are you L. Salvatore?

Claim your profile

Publications (46)34.13 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: The sensorless position control of permanent-magnet motors is successfully implemented by superimposing a high-frequency voltage signal on the voltage reference or adding a high-frequency current signal to the current reference. The former approach is usually preferred because of its simplicity, although the latter one may allow better performance. This paper presents a new algorithm for the sensorless control of low-saliency permanent-magnet synchronous motors based on high-frequency sinusoidal current signal injection into the d -axis. Different from the related literature, the position information is derived by analyzing the measured high-frequency currents. The amplitude of the d -axis voltage reference is also exploited to improve performance. A proportional-integral (PI) controller plus a resonant term (PI-RES) is adopted to ensure the accurate tracking of both the dc and high-frequency components of the d -axis current reference. The main advantages of the proposed approach are the increased accuracy and sensitivity with respect to the approach based on voltage injection, the insensitiveness to inverter nonlinearities that are compensated by the current regulation loop, the actual control on the injected current value, and the practical absence of acoustic noise. Experiments on a linear tubular permanent-magnet synchronous motor prototype have been carried out to verify the aforementioned advantages. This paper also presents a discussion of the parameters of the PI-RES.
    IEEE Transactions on Industry Applications 07/2011; · 1.67 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Phase-locked loop (PLL) algorithms are commonly used to track sinusoidal components in currents and voltage signals in three-phase power systems. Despite the simplicity of those algorithms, problems arise when signals have variable frequency or amplitude, or are polluted with harmonic content and measurement noise, as can be found in aircraft ac power systems where the fundamental frequency can vary in the range 360-900 Hz. To improve the quality of phase and frequency estimates in such power systems, a novel PLL scheme based on a real-time implementation of the discrete Fourier transform (DFT) is presented in this paper. The DFT algorithm calculates the amplitudes of three consecutive components in the frequency domain. These components are used to determine an error signal which is minimized by a proportional-integral loop filter in order to estimate the fundamental frequency. The integral of the estimated frequency is the estimated phase of the fundamental component, and this is fed back to the DFT algorithm. The proposed algorithm can therefore be considered to be a PLL in which phase detection is performed via a DFT-based algorithm. A comparison has been made of the performances of a standard PLL and the proposed DFT-PLL using computer simulations and through experiments.
    IEEE Transactions on Industrial Electronics 04/2011; · 5.17 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The sensorless position control of permanent-magnet (PM) synchronous motors can be successfully implemented by superimposing a high-frequency voltage signal on the control voltage. In this paper, the position estimation is obtained by means of a high-frequency sinusoidal voltage signal injected along the estimated -axis. Several methods proposed in the literature obtain the position estimation by tracking the zero condition of the high-frequency current component. We propose a new approach that also exploits the -axis high-frequency current component and allows working with injected voltage signal of reduced amplitude, thus reducing noise and additional losses. The main contribution of this paper relies in the compensation of the motor end effects due to the finite length of the tubular motor armature. These effects must be taken into account in the motor modeling because they cause an error in the position estimation that varies with the motor position. The modeling of the phenomenon and a proper compensation technique are proposed in this paper. Last, a simplified integral-type controller is used to estimate motor position instead of the commonly adopted proportional-integral controller plus integrator, and this requires a low-effort design. Experiments on a linear tubular PM synchronous-motor prototype are presented to validate the theoretical analysis and evidence the feasibility of the proposed sensorless technique.
    IEEE Transactions on Industrial Electronics 03/2011; · 5.17 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The sensorless control schemes based on machine saliency detection by signal injection commonly adopt a position observer to estimate the motor position. The position observer usually employs proportional-integral-derivative- (PID-) type controllers and low-pass-filters (LPFs) whose parameters need to be properly tuned to achieve satisfactory, or at least stable, performances. Generally, the position observers are tuned with trial and error procedures that require commissioning time and control design experience. This paper deals with the observer modelling and tuning. In particular, the observer model is used for a model-based position control tuning and the effectiveness of the proposed procedure is confirmed by the good agreement of theoretical and experimental results. The experimental test have been realized using both a linear tubular permanent magnet motor (LTPM) and a rotating internal permanent magnet motor (IPM) to demonstrate that the motor control performances can be predicted only if the observer behaviour is considered.
    Energy Conversion Congress and Exposition (ECCE), 2010 IEEE; 10/2010
  • [show abstract] [hide abstract]
    ABSTRACT: Phase locked loop (PLL) algorithms are commonly used to track sinusoidal components in currents and voltage signals in three phase power systems. Despite the simplicity of those algorithms some drawbacks arise when signals have variable amplitude or are polluted with relevant harmonic content and measurement noise. These are typical conditions in aircraft AC power systems, where the fundamental frequency can be variable in the range 360-900 Hz. To improve the quality of phase and frequency estimates in such power systems a novel PLL scheme based on a real-time implementation of discrete fourier transform (DFT) is presented in this paper. The DFT algorithm calculates the amplitudes of three consecutive components in the frequency domain that are used to determine an error signal to be minimized by a PI controller that estimates the fundamental frequency. The integral of the estimated frequency is the estimated phase of the fundamental component that is fed back to the DFT algorithm. The proposed algorithm can be then reviewed as a PLL in which the phase detector is performed via a DFT-based algorithm. A comparison between the performances of standard PLL and the proposed DFT-PLL has been realized using computer simulations and experiments.
    Electric Machines and Drives Conference, 2009. IEMDC '09. IEEE International; 06/2009
  • [show abstract] [hide abstract]
    ABSTRACT: The sensorless position control of permanent magnet motors can be successfully implemented by superimposing a high-frequency voltage on the control voltage. The accuracy of the method relies on a fast and accurate signal processing of the measured quantities and on the compensation of the inverter and motor non idealities. In this paper the position estimation is obtained by adding a high-frequency sinusoidal voltage at the output of the d-axis current controller. According to several methods proposed in the literature the position estimation is obtained by minimizing the high-frequency q-axis current. We propose a new approach that also exploits the analysis of the d-axis high-frequency current. Since this current has reasonable amplitude regardless the position estimation error, the proposed approach allows working with injected voltage of reduced amplitude thus reducing noise and additional losses. Moreover a simple I-type controller is used to estimate rotor position and it requires a low-effort design. Experiments on a linear tubular permanent-magnet motor prototype are presented to compare the performances of the considered estimation techniques.
    Electric Machines and Drives Conference, 2009. IEMDC '09. IEEE International; 06/2009
  • [show abstract] [hide abstract]
    ABSTRACT: The sensorless position control of permanent magnet motors is successfully implemented superimposing an high-frequency voltage signal on the voltage reference or adding a high-frequency current signal to the current reference. The former approach is usually preferred because of its simplicity although the latter one may allow better performance. This paper presents a new algorithm for sensorless control of lows-aliency permanent magnet synchronous motors based on high-frequency sinusoidal current signal injection into the d-axis. Differently from the related literature, the position information is derived by analyzing the measured high-frequency currents. The amplitude of the d-axis voltage reference is also exploited to improve performance. A proportional integral controller plus resonant term is adopted to ensure accurate tracking of both the dc and high-frequency components of the d-axis current reference. The main advantages of the proposed approach are the increased accuracy and sensitivity with respect to the approach based on voltage injection, the insensitiveness to inverter non-linearities that are compensated by the current regulation loop, the actual control on the injected current value, and practical absence of acoustic noise. Experiments on a linear tubular permanent magnet synchronous motor prototype have been carried out to verify the above mentioned advantages. The paper also presents a discussion of the parameters of proportional integral controller plus resonant term.
    Energy Conversion Congress and Exposition, 2009. ECCE 2009. IEEE; 01/2009
  • [show abstract] [hide abstract]
    ABSTRACT: Direct drives with linear permanent magnet synchronous motors (LPMSMs) are recently attracting the attention of both industry and academia. On the one hand such electric drives permit to reduce size and increase reliability thanks to the lack of mechanical reduction and transmission devices. On the other hand precision positioning requires linear position sensing with a measuring range (and size) equal to the motor allowed travel. It is clear the advantage of sensorless control in such applications in terms of reduced hardware complexity, cost and maintenance requirements. This paper presents a position sensorless control scheme based on high frequency signal injection. A pulsating voltage is superimposed to the control voltage along the estimated d-axis direction. Then a novel demodulation procedure implemented in stationary coordinates is proposed to extract position information. The procedure has a reduced computational cost if compared to the alternatives already proposed in the related literature and requires no tuning effort. A demonstration of the algorithm convergence valid in transient conditions, and a novel method to measure the high frequency motor impedance are also presented. The proposed approach is well suited for motors with reduced magnetic saliency such as tubular LPMSM. The above considerations are validated by extensive experiments.
    Industry Applications Society Annual Meeting, 2008. IAS '08. IEEE; 11/2008
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: This paper describes a control system for a tubular synchronous linear motor based on a combination of a linear PID controller and a nonlinear neural network. The nonlinear part of the controller is introduced to progressively augment the tracking performance of the system and is trained online by a compact GA. We implement a variant of a known compact GA that well lends itself to practical implementations in low capacity microcontrollers, thanks to its reduced memory requirements and better distributed computational loads. The potential of the proposed approach is assessed by means of a simulation study on a detailed model of a linear motor. The control system obtained through genetic search outperforms alternative schemes obtained with linear design techniques.
    Evolutionary Computation, 2007. CEC 2007. IEEE Congress on; 10/2007
  • Source
    F. Cupertino, E. Mininno, D. Naso, L. Salvatore
    [show abstract] [hide abstract]
    ABSTRACT: This paper describes the implementation of self-optimizing embedded control schemes for induction motor drives. The online design problem is formulated as a search problem and solved with stochastic optimization algorithms. The objective function takes into account the tracking error, and is directly measured on the hardware bench. In particular, we compare two efficient optimization algorithms, a simultaneous perturbation stochastic approximation method, and a compact genetic algorithm. Both search strategies have very small computational requirements, and therefore can be directly implemented on the same processor running the control algorithm.
    Power Electronics and Applications, 2007 European Conference on; 10/2007
  • [show abstract] [hide abstract]
    ABSTRACT: This paper describes the application of automatic diagnosis procedures for the detection of broken bars in squirrel cage induction machines based on neural network (NN) classifiers. On the ground of representative data of the motor condition, obtained through an appropriate processing of experimental measures, NNs are effectively employed for discriminating healthy and faulty motors and providing a indication of the fault level. Both supervised and unsupervised training algorithms for NNs are used to evaluate their suitability to this kind of task. Two different diagnosis techniques, consisting in analyzing stator currents during start up and stator voltages after supply disconnection respectively, have been experimented to provide suitable input data to the NN for the fault detection. Differently from other diagnosis techniques, they possess the distinctive feature of being insensitive to load conditions. Experimental diagnosis results show the noticeable potentialities of the proposed automatic diagnosis approach that is able to identify the rotor fault in the early stages
    Electric Machines and Drives, 2005 IEEE International Conference on; 06/2005
  • L. Delfine, L. Salvatore
    [show abstract] [hide abstract]
    ABSTRACT: First Page of the Article
    Industrial Electronics, 2005. ISIE 2005. Proceedings of the IEEE International Symposium on; 02/2005
  • [show abstract] [hide abstract]
    ABSTRACT: This paper presents a new technique to estimate the rotor time constant of vector-controlled induction motors (IMs). The estimation is based on the comparison between the expected speed trajectory corresponding to constant acceleration and the actual speed trajectory of the drive. In fact, when the drive operates under vector control with constant torque reference and load, it is expected that the motor has constant acceleration and rectilinear speed trajectory. A simple optimization algorithm, implemented on the same microcontroller used for vector control, updates on-line the rotor time constant trying to minimize the difference between the expected and the actual speed trajectories of the IM. The main advantages of our approach are the complete independence from motor mathematical model, and possibility of implementation on low-cost microcontrollers. Simulation and experimental results are presented to prove the accuracy and the effectiveness of the estimation technique
    01/2005;
  • [show abstract] [hide abstract]
    ABSTRACT: This paper deals with the self-commissioning of electric drives. To improve the performance of self-commissioning on currently available on industrial drives, an on-line auto-tuning based on a hybrid genetic algorithm is proposed. This strategy integrates the simplex method, local searcher, in a genetic framework, global searcher, in order to speed up the convergence. Moreover it is very reliable because experimentally tests each possible solution, consequently the final result is not affected by the accuracy of the motor model. Finally, the proposed on-line hybrid optimization can be embedded as a fully-automated tool without any extra-hardware on industrial drives. Extensive experimental results prove the effectiveness of the proposed approach not only in comparison with conventional commissioning, but also when compared with further accurate hand-calibration
    Power Electronics and Applications, 2005 European Conference on; 01/2005
  • F. Cupertino, M. Marinelli, L. Salvatore
    [show abstract] [hide abstract]
    ABSTRACT: This work presents a performance comparison among algorithms able to estimate in real-time the fundamental component of the current absorbed from the supply by a nonlinear load. This fundamental component can be used to calculate the current reference for an active shunt filter (ASF). The effectiveness of ASFs in reducing the harmonic contents of the supply currents is strictly related to the ability of an algorithm to give a reliable and accurate estimate of the harmonic contents of the load current both at steady-state and in transient conditions. We have considered algorithms based on the use of a synchronous rotating frame (SRF), wavelet analysis, and Kalman filter theory. In order to overcome the problem related to the choice of the covariance matrices of the Kalman filter-based algorithm we propose to use a genetic algorithm (GA) to perform an off-line automatic search for optimal parameters. Experimental results are presented considering a three-phase induction motor drive as nonlinear load.
    Harmonics and Quality of Power, 2004. 11th International Conference on; 10/2004
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: In this paper, we describe an evolutionary design procedure for discrete-time anti-windup controller for electrical drives. Using a genetic algorithm devised to test and compare controllers of different orders, we search for the discrete anti-windup controller achieving the optimal compromise of weighted cost and performance indices. The search is performed on-line, on the physical hardware, by continuously downloading and testing new solutions on a microprocessor running the control algorithms in real time. The controller obtained through genetic search significantly outperforms alternative schemes obtained with conventional design techniques.
    IEEE Transactions on Evolutionary Computation 09/2004; · 4.81 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This paper describes an automatic approach to design discrete-time linear controllers for electric drives. The design procedure is based on a genetic algorithm, which iteratively searches for the controller with the highest satisfaction of a predefined objective function. The fitness of each controller is measured directly on the hardware, and takes into account multiple and conflicting design aspects, such as settling times, overshoots and ripples on the applied current. As confirmed by the experimental results, the proposed approach exhibits interesting potentialities.
    Industrial Electronics, 2004 IEEE International Symposium on; 06/2004
  • [show abstract] [hide abstract]
    ABSTRACT: This paper presents some analysis techniques of the space vector of voltages induced in the stator windings after supply disconnection, to detect broken rotor bars in squirrel-cage induction machines. When the motor is disconnected from the supply no currents flow in the stator windings and the voltages measurable at its terminals are due to flux produced by rotor currents. When the rotor is healthy, the voltages measured at motor terminals are almost sinusoidal because of the symmetry of rotor windings. When there are broken rotor bars, the magnetomotive force generated by rotor windings is distorted, and some particular harmonics, contained in the voltages induced in the stator windings, increase their amplitudes. The diagnostic technique is based on monitoring these voltage harmonics and analyzing the space vector of the voltages induced in the stator windings via MUSIC pseudospectrum and short-time MUSIC (STMUSIC) time-frequency pseudorepresentation. The MUSIC algorithm is based on the eigen analysis of the autocorrelation matrix, and permits us to evidence the principal harmonic frequencies of the signal and decrease the noise influence, thus allowing a better detection of the broken rotor bars. The results obtained using MUSIC and STMUSIC algorithm have been compared experimentally with those obtained by fast Fourier transform (FFT) and short-time FFT, respectively, and two different sized induction motors have been tested, to demonstrate the superiority of the former approach. Differently from most of the diagnostic techniques already proposed in the technical literature, the proposed approach is effective regardless of the load condition of the machine, source characteristics, and iron saturation.
    IEEE Transactions on Industry Applications 04/2004; · 1.67 Impact Factor
  • IEEE Transactions on Evolutionary Computation 01/2004; 8:347-364. · 4.81 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This paper presents some analysis techniques of the space-vector of voltages induced in the stator windings after supply disconnection, to detect broken rotor bars in squirrel cage induction machines. When the motor is disconnected from the supply no currents flow in the stator windings and the voltages measurable at its terminals are due to flux produced by rotor currents. When the rotor is healthy, the voltages measured at motor terminals are almost sinusoidal because of the symmetry of rotor windings. When there are broken rotor bars, the magneto-motive force (m.m.f.) generated by rotor windings results distorted, and some particular harmonics, contained in the voltages induced in the stator windings, increase their amplitudes. The diagnostic technique is based on monitoring these voltage harmonics by analyzing the space vector of the voltages induced in the stator windings via short-time MUSIC (STMUSIC) time-frequency pseudo-representation. The obtained results have been used to train a Kohonen neural-network that is able to automatically classify data measured on healthy and faulty induction motors.
    Industrial Electronics Society, 2003. IECON '03. The 29th Annual Conference of the IEEE; 12/2003