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Christoph M. Hackl received B.Sc., Dipl.-Ing., and Dr.-Ing. (Ph.D.) degrees in Electrical Engineering from Technical University of Munich (TUM), in 2003, 2004, and 2012, respectively. After studying Electrical Engineering (with a focus on controls and mechatronics) at the Technical University of Munich (TUM), Germany, and University of Wisconsin-Madison, USA. In 2018, he became a Professor for Electrical Machines and Drives, and the Head of the “Laboratory for Mechatronic and Renewable Energy Systems (LMRES)” and, in 2019, the Co-Head of the newly founded “Research Institute for Sustainable Energy Systems (ISES)” at the Munich University of Applied Sciences (MUAS), Germany. His research interests include nonlinear, adaptive, and optimal control of electrical, mechatronic, and renewable energy systems.
The efficiency of an IPMSM motor is influenced by the operating point of the machine. Conventional approaches to generate measured efficiency maps may be too expensive to use in some situations, thus it often replaced by simpler variants based on parametric models. A promising approach is to combine model-based approaches with online parameter identification methods which would allow following changes of the parameters. However, such approaches may also result in deteriorated performance if the online parameter estimation is inaccurate. We present a systematic experimental study of the influence of the parameter estimates on the efficiency of a 4.5 kW IPMSM drive and analyze the sources of inaccuracy. The first outcome of this study is that none of the tested methods performs well when the machine is fully loaded, which deteriorates overall performance. The second outcome is that the conventional maximum torque per ampere/current (MTPA/MTPC) is not an accurate optimization criterion. The overall performance of the compared methods thus heavily depends on the testing profile. When a significant part of the profile is at full load, the methods based on online estimation are unsuitable and parameters estimated offline using frequency domain provides better efficiency under the maximum torque per current control strategy.
Antonín Glac; Václav Šmídl; Zdeněk Peroutka; Christoph M. Hackl. Dependence of IPMSM Motor Efficiency on Parameter Estimates. Sustainability 2021, 13, 9299 .
AMA StyleAntonín Glac, Václav Šmídl, Zdeněk Peroutka, Christoph M. Hackl. Dependence of IPMSM Motor Efficiency on Parameter Estimates. Sustainability. 2021; 13 (16):9299.
Chicago/Turabian StyleAntonín Glac; Václav Šmídl; Zdeněk Peroutka; Christoph M. Hackl. 2021. "Dependence of IPMSM Motor Efficiency on Parameter Estimates." Sustainability 13, no. 16: 9299.
In this paper, a deadbeat predictive control (DBPC) technique for doubly-fed induction generators (DFIGs) in wind turbine applications is proposed. The major features of DBPC scheme are its quick dynamic performance and its fixed switching frequency. However, the basic concept of DBPC is computing the reference voltage for the next sample from the mathematical model of the generator. Therefore, the DBPC is highly sensitive to variations of the parameters of the DFIG. To reduce this sensitivity, a disturbance observer is designed in this paper to improve the robustness of the proposed DBPC scheme. The proposed observer is very simple and easy to be implemented in real-time applications. The proposed DBPC strategy is implemented in the laboratory. Several experiments are performed with and without mismatches in the DFIG parameters. The experimental results proved the superiority of the proposed DBPC strategy over the traditional DBPC technique.
Mohamed Abdelrahem; Christoph Hackl; Ralph Kennel; Jose Rodriguez. Low Sensitivity Predictive Control for Doubly-Fed Induction Generators Based Wind Turbine Applications. Sustainability 2021, 13, 9150 .
AMA StyleMohamed Abdelrahem, Christoph Hackl, Ralph Kennel, Jose Rodriguez. Low Sensitivity Predictive Control for Doubly-Fed Induction Generators Based Wind Turbine Applications. Sustainability. 2021; 13 (16):9150.
Chicago/Turabian StyleMohamed Abdelrahem; Christoph Hackl; Ralph Kennel; Jose Rodriguez. 2021. "Low Sensitivity Predictive Control for Doubly-Fed Induction Generators Based Wind Turbine Applications." Sustainability 13, no. 16: 9150.
A not yet available look-up table (LUT) based optimal feedforward torque control (OFTC) method for squirrel- cage induction machines (SCIMs) is presented. It is based on: (i) a generic transformer-like machine model in an arbitrarily rotating (d,q)-reference frame, considering nonlinear flux linkages and iron losses in the stator laminations; (ii) machine identification by evaluating steady-state measurements over a grid of (d,q) stator currents, producing frequency-dependent machine maps for e.g. flux linkages, torque, iron resistance and efficiency; and (iii) numerical optimization and extraction of OFTC look- up tables for optimal stator current references depending on reference torque and electrical frequency. In order to increase reproducibility, a feedback temperature controller is employed to keep the stator winding temperature constant. Moreover, throughout the identification, the electrical frequency is kept con- stant (per data set) by adapting the machine speed accordingly using a speed-controlled prime mover; this way the impact of iron losses becomes more balanced than for constant speed operation. The presented measurement results confirm that compared to constant flux operation or scalar V/Hz control, efficiency can be increased particularly in part-load operation by up to 7 %.
Julian Kullick; Christoph Hackl. Generic modeling, identification and optimal feedforward torque control of induction machines using steady-state machine maps. 2021, 1 .
AMA StyleJulian Kullick, Christoph Hackl. Generic modeling, identification and optimal feedforward torque control of induction machines using steady-state machine maps. . 2021; ():1.
Chicago/Turabian StyleJulian Kullick; Christoph Hackl. 2021. "Generic modeling, identification and optimal feedforward torque control of induction machines using steady-state machine maps." , no. : 1.
A not yet available look-up table (LUT) based optimal feedforward torque control (OFTC) method for squirrel- cage induction machines (SCIMs) is presented. It is based on: (i) a generic transformer-like machine model in an arbitrarily rotating (d,q)-reference frame, considering nonlinear flux linkages and iron losses in the stator laminations; (ii) machine identification by evaluating steady-state measurements over a grid of (d,q) stator currents, producing frequency-dependent machine maps for e.g. flux linkages, torque, iron resistance and efficiency; and (iii) numerical optimization and extraction of OFTC look- up tables for optimal stator current references depending on reference torque and electrical frequency. In order to increase reproducibility, a feedback temperature controller is employed to keep the stator winding temperature constant. Moreover, throughout the identification, the electrical frequency is kept con- stant (per data set) by adapting the machine speed accordingly using a speed-controlled prime mover; this way the impact of iron losses becomes more balanced than for constant speed operation. The presented measurement results confirm that compared to constant flux operation or scalar V/Hz control, efficiency can be increased particularly in part-load operation by up to 7 %.
Julian Kullick; Christoph Hackl. Generic modeling, identification and optimal feedforward torque control of induction machines using steady-state machine maps. 2021, 1 .
AMA StyleJulian Kullick, Christoph Hackl. Generic modeling, identification and optimal feedforward torque control of induction machines using steady-state machine maps. . 2021; ():1.
Chicago/Turabian StyleJulian Kullick; Christoph Hackl. 2021. "Generic modeling, identification and optimal feedforward torque control of induction machines using steady-state machine maps." , no. : 1.
In this article, a deadbeat predictive control (DB-PC) strategy for permanent-magnet synchronous generators (PMSGs)-based modern wind turbines is proposed. The main advantages of the DB-PC technique are its excellent dynamics and its constant switching frequency. However, the main idea of DB-PC is obtaining the actuation voltage for the next sample from the mathematical model of the generator. Therefore, the DB-PC is highly sensitive to mismatches in the parameters of the PMSG. In order to obviate this problem, a disturbance estimator (extended Kalman filter (EKF)) is employed in this work to enhance the robustness of the proposed DB-PC scheme by estimating the total disturbance due to parameter mismatches and adding it to the calculation of the actuation voltage. Furthermore, the same EKF observe the rotor speed and position of the PMSG, i.e., mechanical sensors are not required. Moreover, the EKF is able to reduce the harmonic distortion in the stator currents of the PMSG. The proposed DB-PC strategy is implemented in the laboratory. The experimental results proved the superiority of the proposed DB-PC strategy over the traditional DB-PC technique.
Mohamed Abdelrahem; Christoph Hackl; Ralph Kennel. Robust Predictive Control Scheme for Permanent-Magnet Synchronous Generators Based Modern Wind Turbines. Electronics 2021, 10, 1596 .
AMA StyleMohamed Abdelrahem, Christoph Hackl, Ralph Kennel. Robust Predictive Control Scheme for Permanent-Magnet Synchronous Generators Based Modern Wind Turbines. Electronics. 2021; 10 (13):1596.
Chicago/Turabian StyleMohamed Abdelrahem; Christoph Hackl; Ralph Kennel. 2021. "Robust Predictive Control Scheme for Permanent-Magnet Synchronous Generators Based Modern Wind Turbines." Electronics 10, no. 13: 1596.
An accurate approximation of the dc-link capacitor current is crucial for the design of the dc-link capacitor as the capacitor current ripple affects lifetime, size, weight and cost of the voltage source inverter (VSI). In this paper, analytical expressions for the dc-link capacitor current and the inverter current are derived for two-level VSIs feeding anisotropic interior permanent magnet synchronous machines (IPMSMs) controlled by synchronous opimal pulsewidth modulation (SOPWM). The magnetic anisotropic properties of the IPMSM are considered and half-wave symmetric SOPWM signals are utilized. Experimental results evaluate the effect of various pulse patterns on the produced inverter current and dc-link capacitor current ripples and validate the correctness of the derived expressions.
Athina Birda; Christoph Grabher; Christoph M Hackl; Jorg Reuss. Dc-link capacitor and inverter current ripples in anisotropic synchronous motor drives produced by synchronous optimal PWM. IEEE Transactions on Industrial Electronics 2021, PP, 1 -1.
AMA StyleAthina Birda, Christoph Grabher, Christoph M Hackl, Jorg Reuss. Dc-link capacitor and inverter current ripples in anisotropic synchronous motor drives produced by synchronous optimal PWM. IEEE Transactions on Industrial Electronics. 2021; PP (99):1-1.
Chicago/Turabian StyleAthina Birda; Christoph Grabher; Christoph M Hackl; Jorg Reuss. 2021. "Dc-link capacitor and inverter current ripples in anisotropic synchronous motor drives produced by synchronous optimal PWM." IEEE Transactions on Industrial Electronics PP, no. 99: 1-1.
This paper presents analytic solutions for an optimal modulation scheme featuring low switching losses for a bidirec- tional single-phase dual active bridge (DAB) DC-DC converter used for charging high-voltage batteries of electric vehicles. The proposed modulation scheme facilitates zero-voltage switching (ZVS) for either the primary- or secondary-side full bridge of the DAB converter throughout the whole operating range while maintaining low conduction losses. The expressions are derived based on the current required for an ideal ZVS transition and enable for a direct computation of the respective optimal modulation parameters.
Michael Saegmueller; Christoph Hackl; Rolf Witzmann; Rene Richter. Analytic Solutions for Full Operating Range Single-Side ZVS Modulation of Dual Active Bridge Converters. 2021, 1 .
AMA StyleMichael Saegmueller, Christoph Hackl, Rolf Witzmann, Rene Richter. Analytic Solutions for Full Operating Range Single-Side ZVS Modulation of Dual Active Bridge Converters. . 2021; ():1.
Chicago/Turabian StyleMichael Saegmueller; Christoph Hackl; Rolf Witzmann; Rene Richter. 2021. "Analytic Solutions for Full Operating Range Single-Side ZVS Modulation of Dual Active Bridge Converters." , no. : 1.
This paper presents analytic solutions for an optimal modulation scheme featuring low switching losses for a bidirec- tional single-phase dual active bridge (DAB) DC-DC converter used for charging high-voltage batteries of electric vehicles. The proposed modulation scheme facilitates zero-voltage switching (ZVS) for either the primary- or secondary-side full bridge of the DAB converter throughout the whole operating range while maintaining low conduction losses. The expressions are derived based on the current required for an ideal ZVS transition and enable for a direct computation of the respective optimal modulation parameters.
Michael Saegmueller; Christoph Hackl; Rolf Witzmann; Rene Richter. Analytic Solutions for Full Operating Range Single-Side ZVS Modulation of Dual Active Bridge Converters. 2021, 1 .
AMA StyleMichael Saegmueller, Christoph Hackl, Rolf Witzmann, Rene Richter. Analytic Solutions for Full Operating Range Single-Side ZVS Modulation of Dual Active Bridge Converters. . 2021; ():1.
Chicago/Turabian StyleMichael Saegmueller; Christoph Hackl; Rolf Witzmann; Rene Richter. 2021. "Analytic Solutions for Full Operating Range Single-Side ZVS Modulation of Dual Active Bridge Converters." , no. : 1.
In this work, a novel three-phase grid inverter topology with split DC-link and LC-filter is discussed. A proportionalintegral (PI) state-feedback current and voltage controller is designed based on linear quadratic regulator (LQR) theory. The midpoint current ripple is suppressed by introducing the filter capacitor voltage as control target. Moreover, a 3-dimensional Space Vector Modulation (3D-SVM) for this topology is implemented, which allows for larger voltage amplitudes compared to conventional Pulse Width Modulation (PWM). Realistic simulation results show that the combination of PI state-feedback controller and 3D-SVM achieves faster and more accurate closedloop dynamics with less oscillations and better decoupling under varying and unbalanced grid conditions.
Christoph Hackl; Simon Krüner; Zhao Song. 3D-Modulation and PI State-Feedback Control for Voltage Source Inverters with Split DC-Link. 2021, 1 .
AMA StyleChristoph Hackl, Simon Krüner, Zhao Song. 3D-Modulation and PI State-Feedback Control for Voltage Source Inverters with Split DC-Link. . 2021; ():1.
Chicago/Turabian StyleChristoph Hackl; Simon Krüner; Zhao Song. 2021. "3D-Modulation and PI State-Feedback Control for Voltage Source Inverters with Split DC-Link." , no. : 1.
In this work, a novel three-phase grid inverter topology with split DC-link and LC-filter is discussed. A proportionalintegral (PI) state-feedback current and voltage controller is designed based on linear quadratic regulator (LQR) theory. The midpoint current ripple is suppressed by introducing the filter capacitor voltage as control target. Moreover, a 3-dimensional Space Vector Modulation (3D-SVM) for this topology is implemented, which allows for larger voltage amplitudes compared to conventional Pulse Width Modulation (PWM). Realistic simulation results show that the combination of PI state-feedback controller and 3D-SVM achieves faster and more accurate closedloop dynamics with less oscillations and better decoupling under varying and unbalanced grid conditions.
Christoph Hackl; Simon Krüner; Zhao Song. 3D-Modulation and PI State-Feedback Control for Voltage Source Inverters with Split DC-Link. 2021, 1 .
AMA StyleChristoph Hackl, Simon Krüner, Zhao Song. 3D-Modulation and PI State-Feedback Control for Voltage Source Inverters with Split DC-Link. . 2021; ():1.
Chicago/Turabian StyleChristoph Hackl; Simon Krüner; Zhao Song. 2021. "3D-Modulation and PI State-Feedback Control for Voltage Source Inverters with Split DC-Link." , no. : 1.
In order to analytically solve the optimal feed-forward torque control (OFTC) problem of induction machines (IMs), the unified theory for synchronous machine introduced in [1] is extended by considering relevant IM nonlinearities and incorporating stator and rotor copper losses. Instead of the well known Maximum Torque per (stator) Current (MTPC) operation strategy, Maximum Torque per (copper) Losses (MTPL Cu ) is realized and extended by the Maximum (rotor) Current (MC r, ext ) strategy due to stator and rotor current limitations. Modeling magnetic saturation and cross-coupling effects leads to a con-strained nonlinear optimization problem which is solved based on the idea of sequential quadratic programming (SQP). The second order Taylor approximations are formulated in implicit form as quadrics. Applying the Lagrangian formalism to the quadratic problem leads to analytical solution for the optimal rotor currents. For a doubly-fed induction machine (DFIM), a decision tree for optimal operation management is presented and the OFTC is validated in simulations for a real nonlinear IM.
Christoph Hackl; Andre Thommessen. Optimal feedforward torque control for nonlinear induction machines considering stator & rotor copper losses and current & voltage limits. 2021, 1 .
AMA StyleChristoph Hackl, Andre Thommessen. Optimal feedforward torque control for nonlinear induction machines considering stator & rotor copper losses and current & voltage limits. . 2021; ():1.
Chicago/Turabian StyleChristoph Hackl; Andre Thommessen. 2021. "Optimal feedforward torque control for nonlinear induction machines considering stator & rotor copper losses and current & voltage limits." , no. : 1.
In order to analytically solve the optimal feed-forward torque control (OFTC) problem of induction machines (IMs), the unified theory for synchronous machine introduced in [1] is extended by considering relevant IM nonlinearities and incorporating stator and rotor copper losses. Instead of the well known Maximum Torque per (stator) Current (MTPC) operation strategy, Maximum Torque per (copper) Losses (MTPL Cu ) is realized and extended by the Maximum (rotor) Current (MC r, ext ) strategy due to stator and rotor current limitations. Modeling magnetic saturation and cross-coupling effects leads to a con-strained nonlinear optimization problem which is solved based on the idea of sequential quadratic programming (SQP). The second order Taylor approximations are formulated in implicit form as quadrics. Applying the Lagrangian formalism to the quadratic problem leads to analytical solution for the optimal rotor currents. For a doubly-fed induction machine (DFIM), a decision tree for optimal operation management is presented and the OFTC is validated in simulations for a real nonlinear IM.
Christoph Hackl; Andre Thommessen. Optimal feedforward torque control for nonlinear induction machines considering stator & rotor copper losses and current & voltage limits. 2021, 1 .
AMA StyleChristoph Hackl, Andre Thommessen. Optimal feedforward torque control for nonlinear induction machines considering stator & rotor copper losses and current & voltage limits. . 2021; ():1.
Chicago/Turabian StyleChristoph Hackl; Andre Thommessen. 2021. "Optimal feedforward torque control for nonlinear induction machines considering stator & rotor copper losses and current & voltage limits." , no. : 1.
In this article, we describe the design and implementation of a current controller for a reluctance synchronous machine (RSM) based on continuous control set nonlinear model predictive control (NMPC). A computationally efficient gray box model of the flux linkage map, the Gaussian-linear-arctangent (GLA) model, is proposed and employed in a tracking formulation, which is implemented using the high-performance framework for NMPC acados. The resulting controller is validated in simulation and deployed on a dSPACE real-time system connected to a physical RSM. Experimental results are presented where the proposed implementation can reach sampling times in the range typical for electrical drives and can achieve large improvements in terms of control performance with respect to state-of-the-art classical control strategies.
Andrea Zanelli; Julian Kullick; Hisham M. Eldeeb; Gianluca Frison; Christoph M. Hackl; Moritz Diehl. Continuous Control Set Nonlinear Model Predictive Control of Reluctance Synchronous Machines. IEEE Transactions on Control Systems Technology 2021, PP, 1 -12.
AMA StyleAndrea Zanelli, Julian Kullick, Hisham M. Eldeeb, Gianluca Frison, Christoph M. Hackl, Moritz Diehl. Continuous Control Set Nonlinear Model Predictive Control of Reluctance Synchronous Machines. IEEE Transactions on Control Systems Technology. 2021; PP (99):1-12.
Chicago/Turabian StyleAndrea Zanelli; Julian Kullick; Hisham M. Eldeeb; Gianluca Frison; Christoph M. Hackl; Moritz Diehl. 2021. "Continuous Control Set Nonlinear Model Predictive Control of Reluctance Synchronous Machines." IEEE Transactions on Control Systems Technology PP, no. 99: 1-12.
The unified theory (introduced in [1]), which allowsto analytically solve the optimal feedforward torque control(OFTC) problem of anisotropic synchronous machines (SM),is extended by considering all relevant machine nonlinearitiesand copper and iron losses and, thus, minimizing the overall(steady-state) losses in the machine. Instead of the well known maximum torque per current (MTPC) operation strategy, maximum torque per losses (MTPL) is realized. The unified theory for the derivation of the analytical solution is briefly recapitulated. Moreover, current and speed dependent iron losses, as well as, magnetic saturation and cross-coupling effects are considered. The resulting nonlinear optimization problem is solved via online linearization of the relevant expressions. The linearization is exemplified for flux linkages and machine torque. The presented decision tree guarantees an optimal operation management and smooth transitions between all operation strategies such as MTPL, field weakening (FW), maximum current (MC) and maximum torque per voltage (MTPV). Finally, the extended unified theory is validated for a real, highly nonlinear SM.
Christoph Hackl; Julian Kullick; Niklas Monzen. Generic loss minimization for nonlinear synchronous machines by analytical computation of optimal reference currents considering copper and iron losses. 2020, 1 .
AMA StyleChristoph Hackl, Julian Kullick, Niklas Monzen. Generic loss minimization for nonlinear synchronous machines by analytical computation of optimal reference currents considering copper and iron losses. . 2020; ():1.
Chicago/Turabian StyleChristoph Hackl; Julian Kullick; Niklas Monzen. 2020. "Generic loss minimization for nonlinear synchronous machines by analytical computation of optimal reference currents considering copper and iron losses." , no. : 1.
The unified theory (introduced in [1]), which allowsto analytically solve the optimal feedforward torque control(OFTC) problem of anisotropic synchronous machines (SM),is extended by considering all relevant machine nonlinearitiesand copper and iron losses and, thus, minimizing the overall(steady-state) losses in the machine. Instead of the well known maximum torque per current (MTPC) operation strategy, maximum torque per losses (MTPL) is realized. The unified theory for the derivation of the analytical solution is briefly recapitulated. Moreover, current and speed dependent iron losses, as well as, magnetic saturation and cross-coupling effects are considered. The resulting nonlinear optimization problem is solved via online linearization of the relevant expressions. The linearization is exemplified for flux linkages and machine torque. The presented decision tree guarantees an optimal operation management and smooth transitions between all operation strategies such as MTPL, field weakening (FW), maximum current (MC) and maximum torque per voltage (MTPV). Finally, the extended unified theory is validated for a real, highly nonlinear SM.
Christoph Hackl; Julian Kullick; Niklas Monzen. Generic loss minimization for nonlinear synchronous machines by analytical computation of optimal reference currents considering copper and iron losses. 2020, 1 .
AMA StyleChristoph Hackl, Julian Kullick, Niklas Monzen. Generic loss minimization for nonlinear synchronous machines by analytical computation of optimal reference currents considering copper and iron losses. . 2020; ():1.
Chicago/Turabian StyleChristoph Hackl; Julian Kullick; Niklas Monzen. 2020. "Generic loss minimization for nonlinear synchronous machines by analytical computation of optimal reference currents considering copper and iron losses." , no. : 1.
Operations of the doubly-fed induction generators (DFIGs) without mechanical sensors are highly desirable in order to enhance the reliability of the wind generation systems. This article proposes a limited-position set model-reference adaptive observer (LPS-MRAO) for control of DFIGs in wind turbine systems (WTSs) without mechanical sensors, i.e., without incremental encoders or speed transducers. The concept of of the developed LPS-MRAO is obtained from the finite-set model predictive control (FS-MPC). In the proposed LPS-MRAO, an algorithm is presented in order to give a constant number of angles for the rotor position of the DFIG. By using these angles, a certain number of rotor currents can be predicted. Then, a new quality function is defined to find the best angle of the rotor. In the proposed LPS-MRAO, there are not any gains to tune like the classical MRAO, where a proportional-integral is used and must be tuned. Finally, the proposed LPS-MRAO and classical one are experimentally implemented in the laboratory and compared at various operation scenarios and under mismatches in the parameters of the DFIG. The experimental results illustrated that the estimation performance and robustness of the proposed LPS-MRAO are better than those of the classical one.
Mohamed Abdelrahem; Christoph M. Hackl; Ralph Kennel. Limited-Position Set Model-Reference Adaptive Observer for Control of DFIGs without Mechanical Sensors. Machines 2020, 8, 72 .
AMA StyleMohamed Abdelrahem, Christoph M. Hackl, Ralph Kennel. Limited-Position Set Model-Reference Adaptive Observer for Control of DFIGs without Mechanical Sensors. Machines. 2020; 8 (4):72.
Chicago/Turabian StyleMohamed Abdelrahem; Christoph M. Hackl; Ralph Kennel. 2020. "Limited-Position Set Model-Reference Adaptive Observer for Control of DFIGs without Mechanical Sensors." Machines 8, no. 4: 72.
The paper presents a controller design for grid-connected inverters (GCI) with very small dc-link capacitance that are coupled to the grid via an LCL filter. The usual controller designs would fail and result in instability. The proposed controller has a cascaded structure with a current controller as inner control loop and an outer dc-link voltage controller. The controller design is performed in discrete time and it is based on a detailed stability analysis of the dc-link voltage controller to determine the controller parameters which guarantee stability for all operating points. The inner loop is a state-feedback current controller that is designed based on the discrete linear-quadratic regulator (DLQR) theory. An additional integral error feedback assures steady-state accuracy of the current control loop. The simulation and experimental results validate performance and stability of proposed controller design.
Oliver Kalmbach; Christian Dirscherl; Christoph M. Hackl. Discrete-Time DC-Link Voltage and Current Control of a Grid-Connected Inverter with LCL-Filter and Very Small DC-Link Capacitance. Energies 2020, 13, 5613 .
AMA StyleOliver Kalmbach, Christian Dirscherl, Christoph M. Hackl. Discrete-Time DC-Link Voltage and Current Control of a Grid-Connected Inverter with LCL-Filter and Very Small DC-Link Capacitance. Energies. 2020; 13 (21):5613.
Chicago/Turabian StyleOliver Kalmbach; Christian Dirscherl; Christoph M. Hackl. 2020. "Discrete-Time DC-Link Voltage and Current Control of a Grid-Connected Inverter with LCL-Filter and Very Small DC-Link Capacitance." Energies 13, no. 21: 5613.
In micro-grid systems, wind turbines are essential power generation sources. The direct-driven surface-mounted permanent-magnet synchronous generators (SMPMSGs) in variable-speed wind generation systems (VS-WGSs) are promising due to their high efficiency/power density and the avoidance of using a gearbox, i.e., regular maintenance and noise are averted. Usually, the main goal of the control system for SMPMSGs is to extract the maximum available power from the wind turbine. To do so, the rotor position/speed of the SMPMSG must be known. Those signals are obtained by the help of an incremental encoder or speed transducer. However, the system reliability is remarkably reduced due to the high failure rate of these mechanical sensors. To avoid this problem, this paper presents a model reference adaptive system with finite-set (MRAS-FS) observer for encoderless control of SMPMSGs in VS-WGSs. The motif of the presented MRAS-FS observer is taken from the direct-model predictive control (DMPC) principle, where a certain number of rotor position angles are utilized to estimate the stator flux of the SMPMSG. Subsequently, a new optimization criterion (also called quality or cost function) is formulated to select the best rotor position angle based on minimizing the error between the estimated and reference value of the stator flux. Accordingly, the traditional fixed-gain proportional-integral regulator generally employed in the classical MRAS observers is not needed. The proposed MRAS-FS observer is validated experimentally, and its estimation response has been compared with the conventional MRAS observer under different conditions. In addition to that, the robustness of the MRAS-FS observer is tested at mismatches in the parameters of the SMPMSG.
Mohamed Abdelrahem; Christoph M. Hackl; José Rodríguez; Ralph Kennel. Model Reference Adaptive System with Finite-Set for Encoderless Control of PMSGs in Micro-Grid Systems. Energies 2020, 13, 4844 .
AMA StyleMohamed Abdelrahem, Christoph M. Hackl, José Rodríguez, Ralph Kennel. Model Reference Adaptive System with Finite-Set for Encoderless Control of PMSGs in Micro-Grid Systems. Energies. 2020; 13 (18):4844.
Chicago/Turabian StyleMohamed Abdelrahem; Christoph M. Hackl; José Rodríguez; Ralph Kennel. 2020. "Model Reference Adaptive System with Finite-Set for Encoderless Control of PMSGs in Micro-Grid Systems." Energies 13, no. 18: 4844.
A unified method is presented which allows to estimate dc-offset, all harmonic components and fundamental frequency in arbitrarily distorted single-phase grids using a Frequency Adaptive Observer(FAO)consisting of modified Second-Order Generalized Integrators (mSOGIs), an adaptive DC-Integrator(DCI) and a modified Frequency Locked Loop (mFLL). DCI and mSOGIs are tuned by pole placement which allows for an arbitrarily fast detection of dc-offset and harmonic components if the fundamental frequency is known. If the fundamental frequency must be estimated as well, a mFLL with Gain Normalization (GN), Rate Limitation (RL), Anti-Windup (AW) strategy and low-pass filters (LPF) must be employed. The effectiveness of the proposed FAO is validated by experimental results and its enhanced performance is shown and compared to existing estimation methods.
Christoph Hackl; Markus Landerer. A Unified Method for Generic Signal Parameter Estimation of Arbitrarily Distorted Single-Phase Grids With DC-Offset. IEEE Open Journal of the Industrial Electronics Society 2020, 1, 235 -246.
AMA StyleChristoph Hackl, Markus Landerer. A Unified Method for Generic Signal Parameter Estimation of Arbitrarily Distorted Single-Phase Grids With DC-Offset. IEEE Open Journal of the Industrial Electronics Society. 2020; 1 (99):235-246.
Chicago/Turabian StyleChristoph Hackl; Markus Landerer. 2020. "A Unified Method for Generic Signal Parameter Estimation of Arbitrarily Distorted Single-Phase Grids With DC-Offset." IEEE Open Journal of the Industrial Electronics Society 1, no. 99: 235-246.
Finite-control-set model predictive control (FCS-MPC) techniques have been widely applied for power electronics and motor drive. Furthermore, the principles of FCS-MPC have been extended to phase locked loop (PLL), which called finite position set PLL (FPS-PLL), for sensorless control of permanent-magnet synchronous generators (PMSGs) in wind turbine applications (WTAs). However, 64 iterations are essential to find the optimal rotor position, i.e high computational burden. In this paper, two computationally-efficient (CE) FPS-PLLs are proposed for encoderless control of PMSGs in WTAs. The first CE-FPS-PLL1 reduces the number of iterations to 36 with slightly better accuracy than the FPS-PLL, while the second (novel) CE-FPS-PLL2 calls for only 24 iterations to find the best rotor position with significantly better accuracy than the FPS-PLL. The performance of the proposed CE-FPS-PLLs have been experimentally investigated and compared with that of the FPS-PLL and classical PLL using a 14.5 kW PMSG. Furthermore, the robustness of the proposed CE-FPS-PLLs is investigated against variations of the PMSG parameters.
Mohamed Abdelrahem; Christoph M. Hackl; Ralph Kennel; Jose Rodriguez. Computationally Efficient Finite-Position-Set-Phase-Locked Loop for Sensorless Control of PMSGs in Wind Turbine Applications. IEEE Transactions on Power Electronics 2020, 36, 3007 -3016.
AMA StyleMohamed Abdelrahem, Christoph M. Hackl, Ralph Kennel, Jose Rodriguez. Computationally Efficient Finite-Position-Set-Phase-Locked Loop for Sensorless Control of PMSGs in Wind Turbine Applications. IEEE Transactions on Power Electronics. 2020; 36 (3):3007-3016.
Chicago/Turabian StyleMohamed Abdelrahem; Christoph M. Hackl; Ralph Kennel; Jose Rodriguez. 2020. "Computationally Efficient Finite-Position-Set-Phase-Locked Loop for Sensorless Control of PMSGs in Wind Turbine Applications." IEEE Transactions on Power Electronics 36, no. 3: 3007-3016.