[comp] Sähkötekniikan korkeakoulu / ELEC

Permanent URI for this collectionhttps://aaltodoc.aalto.fi/handle/123456789/77

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Browsing [comp] Sähkötekniikan korkeakoulu / ELEC by Department "Department of Electrical Engineering and Automation"

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  • Analysis and design of a position observer with resistance adaptation for synchronous reluctance motor drives
    (2011) Tuovinen, Toni; Hinkkanen, Marko; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    A back-EMF-based reduced-order position observer with stator-resistance adaptation is analyzed for motion-sensorless synchronous reluctance motor drives. Analytical equations for steady-state estimation errors and stability conditions are derived (with and without resistance adaptation), taking into account errors in the parameter estimates. The effect of the observer gain on the noise reduction is studied by means of eigenvector analysis. A robust gain selection is proposed, which maximizes the allowed uncertainties in the parameter estimates. The proposed observer design is experimentally evaluated using a 6.7-kW synchronous reluctance motor drive; stable operation is demonstrated at low speeds under various parameter errors.
  • Analysis and design of a position observer with stator-resistance adaptation for PMSM drives
    (2010) Hinkkanen, Marko; Tuovinen, Toni; Harnefors, Lennart; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper deals with reduced-order observers with stator-resistance adaptation for motion-sensorless permanent-magnet synchronous motor drives. An analytical solution for the stabilizing observer gain and stability conditions for the stator-resistance adaptation are derived. The proposed observer design is experimentally tested using a 2.2-kW motor drive; stable operation at very low speeds under different loading conditions is demonstrated.
  • Augmented Reality in Forest Machine Cabin
    (2017) Palonen, Tuomo; Hyyti, Heikki; Visala, Arto
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    Augmented reality human machine interface is demonstrated in the cabin of a forest machine outdoors for the first time in real time. In this work, we propose a system setup and a real-time capable algorithm to augment the operator’s visual field with measurements from the forest machine and its environment. In the demonstration, an instrumented forestry crane and a lidar are used to model the pose of the crane and its surroundings. In our approach, a camera and an inertial measurement unit are used to estimate the pose of the operator’s head in difficult lighting conditions with the help of planar markers placed on the cabin structures. Using the estimate, a point cloud and a crane model are superimposed on the video feed to form an augmented reality view. Our system is tested to work outdoors using a forest machine research platform in real time with encouraging initial results.
  • A comparison of an adaptive full-order observer and a reduced-order observer for synchronous reluctance motor drives
    (2011) Tuovinen, Toni; Hinkkanen, Marko; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    Two back-EMF-based position observers are compared for motion-sensorless synchronous reluctance motor drives. The reduced-order observer is of the second order, and the adaptive full-order observer is of the fourth order. The proposed design rules guarantee the stability of the adaptive full-order observer, if the parameter estimates are accurate. The observers are experimentally evaluated using a 6.7-kW synchronous reluctance motor drive in low-speed operation and under parameter errors. The gain selection of the second-order observer is easier, but the adaptive full-order observer is more robust against parameter variations and spatial harmonics.
  • Current control for IPMSM drives: Direct discrete-time pole-placement design
    (2015) Hinkkanen, Marko; Qu, Zengcai; Awan, Hafiz Asad Ali; Tuovinen, Toni; Briz, Fernando
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper deals with discrete-time models and current control methods for synchronous motors with a magnetically anisotropic rotor structure, such as interior permanent-magnet synchronous motors (IPMSMs) and synchronous reluctance motors (SyRMs). Dynamic performance of current controllers based on continuous-time models is limited, especially if the ratio of the sampling frequency to the fundamental frequency is low. An exact closed-form hold-equivalent discrete motor model is derived. The zero-order hold of the stator-voltage input is modeled in stationary coordinates, where it physically is. An analytical discrete-time pole-placement design method for a two-degree-of-freedom state-space current controller with an integral action is proposed. The proposed method is easy to apply: only the desired closed-loop bandwidth and the three motor parameters (R_s, L_d, L_q) are required. The robustness of the proposed current control design against parameter errors is analyzed. The controller is experimentally verified using a 6.7-kW SyRM drive.
  • Detection and species classification of young trees using machine perception for a semi-autonomous forest machine
    (2015) Vihlman, Mikko; Hyyti, Heikki; Kalmari, Jouko; Visala, Arto
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    An approach to automatically detect and classify young spruce and birch trees in forest environment is presented. The method could be used in autonomous or semi-autonomous forest machines during tending operations. Detection is done by segmenting laser range images formed by a rotating laser scanner. Classification is done with a two-class Naive Bayes classifier based on image texture features. Multiple combinations of 99 features were tested and the best classifier included eight features from the co-occurrence matrix, local binary patterns, statistical geometrical features and Gabor filter. 79% of spruces and birches in the testing material were detected and 74% of these were correctly classified. Results suggest that the approach is suitable but there are still some challenges in each of the processing steps. Iteration between segmentation and classification is needed to increase reliability.
  • Digital implementation of full-order flux observers for induction motors
    (2002) Hinkkanen, Marko; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper deals with flux estimation for induction motor drives by using a full-order flux observer. A problem of full-order flux observers is their need for computationally demanding discretization methods in order to work stably and accurately at high speeds. An implementation of the full-order flux observer using the stator and rotor fluxes as state variables in the stator reference frame and in the rotor reference frame, respectively, was recently proposed. This paper describes how an observer gain can be included in this structure. It is shown that discretization errors of the proposed implementation are small and that there is more freedom to choose an observer gain, even if the simple forward Euler discretization is used.
  • Discrete-time observer design for sensorless synchronous motor drives
    (2015) Tuovinen, Toni; Awan, Hafiz Asad Ali; Saarakkala, Seppo E.; Hinkkanen, Marko
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper deals with the speed and position estimation of interior permanent-magnet synchronous motor (IPMSM) and synchronous reluctance motor (SyRM) drives. A speed adaptive full-order observer is designed and analyzed in the discrete-time domain. The observer design is based on the exact discrete-time motor model, which inherently takes the delays in the control system into account. The proposed observer is experimentally evaluated using a 6.7-kW SyRM drive. The analysis and experimental results indicate that drastic performance improvements can be obtained with the direct discrete-time design, especially if the sampling frequency is relatively low compared to the fundamental frequency.
  • Hybrid Microassembly in Environmental Scanning Electron Microscope Using Robotic Manipulator and Adhesives
    (2014) Liimatainen, Ville; Virta, Antti; Routa, Iiris; Zhou, Quan
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
  • Inclusion of hysteresis and eddy current losses in dynamic induction machine models
    (2009) Ranta, Mikaela; Hinkkanen, Marko; Dlala, Emad; Repo, Anna-Kaisa; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussaä
    This paper proposes a method for including both hysteresis losses and eddy current losses in the dynamic space vector model of induction machines. The losses caused by the rotation and magnitude changes of the flux vector are taken into account. The model can be applied, for example, to time-domain simulations and real-time applications such as drive control. Finite element analysis, simulations, and laboratory experiments of a 45-kW motor are used for the investigation. It is shown that the model can predict the iron losses in a wide frequency range. The accuracy is significantly improved as compared to earlier models.
  • Inclusion of hysteresis and eddy current losses in nonlinear time-domain inductance models
    (2011) Ranta, Mikaela; Hinkkanen, Marko; Belahcen, Anouar; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    A time-domain model including the core losses of a nonlinear inductor is proposed. The model can be seen as a parallel combination of a nonlinear inductance modelling the saturation and a nonlinear resistance modelling the core losses. The desired steady-state core-loss profile is used to determine the resistance function. The model is easy to implement and can be used in many different applications. The hysteresis loop of an electrical steel sample is measured at several frequencies in order to experimentally validate the model. It is shown that the model is able to predict both major and minor hysteresis loops very well.
  • Inclusion of magnetic saturation in dynamic models of synchronous reluctance motors
    (2012) Qu, Zengcai; Tuovinen, Toni; Hinkkanen, Marko
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper deals with the modeling of the magnetic saturation in synchronous reluctance motors (SyRMs). The saturation is modeled by means of analytical expressions, which can be easily embedded in dynamic equivalent-circuit models. A modified power function—proposed in this paper—can take into account the cross saturation between the orthogonal windings, it is physically consistent, and the number of its parameters is small. The function can be used in real-time control applications and in computer simulations. The model fits well to the experimentally measured inductances of a 6.7-kW SyRM. As an application example, the proposed saturation model was implemented in a full-order observer of a motion-sensorless drive, and experimental results are shown.
  • Inductance identification of an induction machine taking load-dependent saturation into account
    (2008) Ranta, Mikaela; Hinkkanen, Marko; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    The paper proposes an identification method for the inductances of induction machines, based on signal injection. Due to magnetic saturation, a saturation-induced saliency appears in the induction motor, and the total leakage inductance estimate depends on the angle of the excitation signal. The proposed identification method is based on a small-signal model that includes the saturation-induced saliency. Because of the saturation, the load also affects the estimate, and measurements are needed in different operating points. Using the identified total leakage inductance, an estimate of the stator inductance can be obtained. The identification method is applied to computer simulations and laboratory experiments of a 2.2-kW induction motor.
  • Influence of magnetic saturation on induction motor model selection
    (2006) Hinkkanen, Marko; Repo, Anna-Kaisa; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    Effects of magnetic saturation on various equivalent circuit models of an induction motor are studied. The parameters of 2.2-kW and 37-kW motors with closed rotor slots are analyzed using finite element computations. Both skewed and unskewed rotor slots are studied. The magnetizing inductance not only depends on the main flux, but is also dependent on the rotor current, especially if the rotor slots are skewed or closed. The stator leakage inductance is essentially constant, while the rotor leakage inductance depends significantly on the rotor current. The performance of vector-controlled drives can be improved by using a T or Γ-equivalent circuit model whose inductances also depend on the rotor current.
  • Loss-minimizing control of synchronous reluctance motors — A review
    (2013) Qu, Zengcai; Hinkkanen, Marko
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper reviews state-of-the-art loss-minimizing control strategies for synchronous reluctance motors. Methods can be categorized as loss-model controllers (LMCs) and search controllers (SCs). For LMCs, different loss models and the corresponding optimal solutions are summarized. The effects of the core losses and magnetic saturation on the optimal stator current are investigated; magnetic saturation is a more important factor than the core losses. For SCs, different search algorithms are presented and compared. The SCs are evaluated based on their convergence speed, parameter sensitivity, accuracy, and the torque ripple caused by the search process.
  • Minimizing losses of a synchronous reluctance motor drive taking into account core losses and magnetic saturation
    (2014) Qu, Zengcai; Tuovinen, Toni; Hinkkanen, Marko
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    This paper proposes a loss-minimizing controller for synchronous reluctance motor drives. The proposed method takes core losses and magnetic saturation effects into account. The core-loss model consists of hysteresis losses and eddy-current losses. Magnetic saturation is modeled using two-dimensional power functions considering cross coupling between the d- and q-axes. The efficiency optimal d-axis current is calculated offline using the loss model and motor parameters. Instead of generating a look-up table, an approximate function was fitted to the loss-minimizing results. The loss-minimizing method is applied in a motion-sensorless drive and the results are validated by measurements.
  • Modeling of Mutual Saturation in Induction Machines
    (2008) Tuovinen, Toni; Hinkkanen, Marko; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    Mutual saturation between the main flux and the rotor leakage flux appears in induction machines, especially if the rotor slots are skewed or closed. Conventional saturation models used in connection with dynamic equivalent-circuit models do not take this phenomenon into account. In this paper, explicit functions for modeling the mutual saturation are proposed. The proposed functions are physically reasonable, they are easy to fit, and the number of their parameters is small. The proposed functions can be used in real-time applications and in computer simulations where high accuracy and physical consistency are preferable. The model fits well to the data obtained from finite element analysis or experimental data of a 2.2-kW motor.
  • Online identification of parameters defining the saturation characteristics of induction machines
    (2012) Ranta, Mikaela; Hinkkanen, Marko
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    The induction machine model parameters need to be estimated with good accuracy to ensure a good performance of the drive. Due to the magnetic saturation, the inductances vary as a function of the flux level. The magnetizing curve can be identified at standstill, but more accurate results are obtained if the identification is performed as the machine is running. In this paper, the magnetic saturation is modelled using a power function, and adaptation laws for the function parameters are proposed. The adaptation method is implemented in the control system of a sensorless drive. Experimental results on a 2.2-kW machine show that the identification of the stator inductance is rapid and the accuracy is good.
  • Parameter estimation of an LCL filter for control of grid converters
    (2015) Koppinen, Jussi; Kukkola, Jarno; Hinkkanen, Marko
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    Model-based control techniques are frequently used with grid-connected converters. This paper proposes a method for identifying model parameters of an LCL filter connected to a grid converter for control purposes. In identification, a discrete-time autoregressive moving average with exogenous input (ARMAX) model structure is used and closed-loop current control is considered. The resulting discrete-time model parameters are translated into the continuous-time physical parameters (inductance and capacitance values of the filter) by comparing the estimated discrete-time model with the analytical discrete-time model. Simulation and experimental results show that the proposed method yields good parameter estimates that are suitable for control tuning.
  • A reduced-order position observer with stator-resistance adaptation for PMSM drives
    (2010) Hinkkanen, Marko; Tuovinen, Toni; Harnefors, Lennart; Luomi, Jorma
     School of Electrical Engineering | A4 Artikkeli konferenssijulkaisussa
    A reduced-order position observer with stator-resistance adaptation is proposed for motion-sensorless permanent-magnet synchronous motor drives. A general analytical solution for the stabilizing observer gain and stability conditions for the stator-resistance adaptation are derived. Under these conditions, the local stability of the position and stator-resistance estimation is guaranteed at every operating point except the zero frequency, if other motor parameters are known. The proposed observer design is experimentally tested using a 2.2-kW motor drive; stable operation at very low speeds under different loading conditions is demonstrated.