EPE Association: EPE 2007 - Subtopic 07-3 - DS: Optimal control, robust control, non-linear control

EPE 2007 - Subtopic 07-3 - DS: Optimal control, robust control, non-linear control
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2007 - Conference > EPE 2007 - Topic 07: 'Application of control methods to electrical systems' > EPE 2007 - Subtopic 07-3 - DS: Optimal control, robust control, non-linear control

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   A Buck-Boost bidirectional converter to drive piezoelectric actuators
By GALCERAN ARELLANO Samuel; MONTESINOS MIRACLE Daniel; GOMIS BELLMUNT Oriol; SUDRIA ANDREU Antoni [View]
[Download]

Abstract: The present work deals with the development and control of a converter to drive piezoelectric actuators. In order to maximize the field in the piezoelectric ceramic important voltages are needed. To fulfill such requirements with a limited input voltage a bidirectional buck-boost converter is proposed. The converter is controlled by means of a sliding mode control strategy. The converter is validated by means of simulations.

   A MATHEMATICAL DESCRIPTION OF CONTROL METHOD ON THE BASIS OF DIFFERENCE CORRECTION
By SKOVPEN Sergey; ISKHAKOV Albert [View]
[Download]

Abstract: In this paper, a mathematical description of the control method on the basis of difference correction applying to sampled-data systems is considered. The difference correction is an efficient way to improving the dynamic characteristics of the pulse power converters, which work is described by difference equations. Proposed method allows transforming a difference equation so that the roots of the characteristic equation become equal to zero. Herewith the maximum speed of convergence of transient to a steady value in the field of it's environ under perturbations of system parameters is achieved. Using the example of a system for stabilizing the load current of a buck converter it is shown that the transient is completed within two or three periods.

   A new method of adaptive predictive control in multimass electromechanical systems with variable parameters
By PODBORSKY Pavel; KOLESNIKOV Artem; WINTERNHEIMER Stefan [View]
[Download]

Abstract: A method of synthesis adaptive locally-optimum control with predicting model for electromechanical systems with casual parameters is presented in detail. Thus for decision of a problem to estimate the changing parameters the theory of multilayered artificial neural networks methods are involved. The method is verified on a two-mass electromechanical systems with casual parameters.

   Accurate Sliding-Mode Control System Modeling for Buck Converters
By HOYERBY Mikkel; ANDERSEN Michael [View]
[Download]

Abstract: This paper shows that classical sliding mode theory fails to correctly predict the output impedance of the highly useful sliding mode PID compensated buck converter. The reason for this is identified as the assumption of the sliding variable being held at zero during sliding mode, effectively modeling the hysteretic comparator as an infinite gain. Correct prediction of output impedance is shown to be enabled by the use of a more elaborate, finite-gain model of the hysteretic comparator, which takes the effects of time delay and finite switching frequency into account. The demonstrated modeling approach also predicts the self-oscillating switching action of the sliding-mode control system correctly. Analytical findings are verified by simulation as well as experimentally in a 10-30V/3A buck converter.

   An Online Control Strategy for a Modular DC Coupled Hybrid Power System
By LINGEMANN Max; ORTJOHANN Egon; MORTON Danny; MOHD Alaa; OMARI Osama [View]
[Download]

Abstract: This paper describes how different power sources of a hybrid power system may be connected together through a DC bus and then to a grid through a main inverter in such a way that a decoupling between the state variables of the power sources and the state variables of the grid is achieved. A layout showing such a structure will be presented, and an online control strategy for this layout will be developed to show that it is modular, expandable and easily controllable. The behavior of such a structure under different load and meteorological conditions will be investigated by applying the developed control strategy to a simulation model. Moreover, a PV/battery hybrid power system was successfully built up including control functions for the system management. These control functions have been developed and integrated into a standard industrial soft PLC terminal. Finally, the results of the simulation and experimental case study will be introduced and discussed.

   Comparative Study of Two Predictive Direct Power Control Algorithms for Three-Phase AC/DC Converters
By ANTONIEWICZ Patrycjusz; AURTENECHEA Sergio; RODRIGUEZ Miguel; KAZMIERKOWSKI Marian P. [View]
[Download]

Abstract: In this paper two predictive direct power control (P-DPC) algorithms developed by authors for a three-phase AC/DC converter are presented and compared. In the first, a variable switching frequency (VSF) algorithm, behavior of active and reactive power is predicted for all available voltage vectors generated by the AC/DC converter and the voltage vector which minimizes a cost function is selected for the next sampling period. The second, a constant switching frequency (CSF) algorithm, in every sampling period selects the voltage-vectors' sequences and computes their application instants in order to minimize tracking error of active- and reactive-power. Experimental results measured on 5 kVA laboratory AC/DC converter show performance of both P-DPC algorithms in stationary and transient states.

   Convergence Test of Model Reference Signal Adaptive SRM Drives
By SZAMEL Laszlo [View]
[Download]

Abstract: Nowadays switched reluctance motor (SRM) drives have been widely used in the field of controlled electric motor drives. The paper proposes a model reference signal adaptive control method for SRM drives. The main goal of the drive control is to improve dynamical performance by compensating for the motor nonlinearities. The adaptation practically works only in a relatively narrow speed error track (adaptation range) which is equal to approximately 20-100 revolution/min absolute value of speed error. The drawback of this limitation is the relatively short time for the algorithm to operate. At the same time the convergence of the algorithm is extremely fast which significantly reduces the effect of this drawback. Two more important advantages emerge when adaptation works only with small speed errors. First of all the controller at changing drive parameters adapts to parameters around the value specified by speed reference signal which also assists to speed the adaptation. The other significant positive effect is the disappearing of the problem coming from nonlinear systems that the response of the system can even differ in its character when the value, amplitude of the reference signal is changed. The convergence test of this control method was performed in an experimental drive system. A SRM of 6/8 pole and 4 kW rated power was used. Simulation and experimental results are presented.

   Design of current controller in an AC drive using a state stimulator concept
By LUKASIAK Przemyslaw; DĘBOWSKI Andrzej [View]
[Download]

Abstract: In the paper a new design method for finding the structure of the current controllers in electric drive on the example of an AC drive with induction motor is proposed. This method uses the approach based on the theory of dual-observers, proposed some years ago by D. G. Luenberger for improving the dynamic transients in the autonomous systems with the feedback loop. This approach was extended by one of the authors to the non-autonomous systems with external control. The modified dual-observer, being a special kind of state compensator, was called a "state stimulator". The method, described in this paper for indirectly controlled induction motor, can be used for design of current control loops in other kinds of electric drives as well.

   Friction compensation for a robust H∞-optimal position control of low order for a multi-mass system
By JOOST Matthias; ORLIK Bernd [View]
[Download]

Abstract: Controlling a multi-mass system is a common problem in industrial automation. Varying or unknown parameters, especially friction, make the control problem more difficult. A powerful tool to control systems with uncertain parameters is a robust H∞-controller. Furthermore, high static friction often still causes problems like stick slip effects. Therefore, friction compensation is needed in addition to a robust controller. This paper will present a simple yet robust friction compensation used in tandem with a robust H∞-controller. Measurements will complete the paper.

   LOOP-SHAPING Hâˆž CONTROL FOR A DOUBLY FED INDUCTION MOTOR
By SALLOUM George [View]
[Download]

Abstract: This paper deals with a Doubly Fed Induction Machine (DFIM) where both sides are supplied by two PWM inverters. The study consists in elaborating a robust vector control of the machine by the loop-shaping H∞ approach. The H∞ loop-shaping theory is presented in brief; then it is applied to the control of the DFIM. The simulation results prove that the implementation of the H∞ controllers for currents, fluxes and speed loops leads to excellent robustness in stability and good dynamic performance even with large electrical and mechanical parameters uncertainty.

   Maximum Torque/Minimum Flux Control of Interior Permanent Magnet Synchronous Motor Based on Magnetic Energy Model
By TSUCHIYA Takeshi; TOSHIAKI Murata; TAKIGUCHI Masashi; TAMURA Junji [View]
[Download]

Abstract: This paper presents a field oriented direct torque control system in Interior Permanent Magnet Synchronous Motor (IPMSM) which controls torque to be the maximum and flux to be the minimum simultaneously. A PWM inverter-fed IPMSM control system has been driven by field oriented control algorithm without chattering by sliding mode control. The validity of the proposed method is confirmed by simulation results.

   Modified Sliding Mode Controller for Positioning of Micro Linear Motors
By MERTENS Axel; DEMMIG Sven; WIEDMANN Karsten [View]
[Download]

Abstract: This paper reports on the control of micro linear motors using a modified sliding mode controller. To have an optimised dynamic behaviour the gradient of the sliding surface is calculated online instead of having a constant value. Simulations and measurements are presented to show the performance of the algorithm.

   Nonlinear adaptive control of a magnetic bearing
By STAMANN Mario; SCHALLSCHMIDT Thomas; PALIS Stefan [View]
[Download]

Abstract: The presented paper shows how nonlinear adaptive control theory can be applied to magnetic bearings. Here the backstepping formalism is used to derive a stabilizing control law, which guarantees stability in the sense of Lyapunov in the presence of a unknown load. The efficiency of the proposed method comparing to linear standard design (e.g. PID) is demonstrated through experimental investigations.

   Robust performance of self-scheduled LPV control of doubly-fed induction generator in wind energy conversion systems
By NGUYEN TIEN Hung; M.A. SCHERPEN Jacquelien; W. SCHERER Carsten [View]
[Download]

Abstract: This paper describes the design of a self-scheduled current controller for doubly-fed induction generators in wind energy conversion systems (WECS). The design is based on viewing the mechanical angular speed as an uncertain yet online measurable parameter and on subsuming the problem into the framework of linear parameter-varying (LPV) controller synthesis. An LPV controller is then synthesized to guarantee a bound on the worst-case energy gain for all admissible trajectories of rotor speed in the operating range. Furthermore, this study investigates the robust performance of the LPV controller with respect to other bounded machine parameter variations and the impact of the stator voltage dips on the robustness of the control system. Two closed loop simulation models, one with a conventional control scheme and the other with an LPV control scheme, are developed for the control of the electrical torque and the power factor on the rotor side in order to compare the performance of the control systems. Some simulation results are given to demonstrate the performance and robustness of the control algorithm.

   State Control of an Electromagnetic Guiding System for Ropeless Elevators
By SCHMÃœLLING Benedikt; EFFING Oliver; HAMEYER Kay [View]
[Download]

Abstract: One major challenge in modern elevator construction is the design of systems, which satisfy the requirements of very high buildings. In this sense conventional elevators with mechanical guides came to their application limitations. An opportunity to optimize the passenger traffic in very high buildings and also in very deep mining applications is an elevator system driven by linear motors instead of traction sheave and ropes. This system can be improved by using non-contact electromagnetic guides instead of a conventional mechanical guiding system. The aim of this work is the implementation of a feedback control for such an active magnetic guiding system for an elevator car in a simulation model. At first, an overview over the applied elevator system is presented. Functionality of drive and guiding system is explained. Afterwards, the design of the simulation model and the derivation of a multi variable state control for the elevator car guiding are shown. Finally, results are presented and analyzed, which show the feasibility of the entire elevator system.

EPE 2007 - Subtopic 07-3 - DS: Optimal control, robust control, non-linear control
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2007 - Conference > EPE 2007 - Topic 07: 'Application of control methods to electrical systems' > EPE 2007 - Subtopic 07-3 - DS: Optimal control, robust control, non-linear control
	[return to parent folder]

	A Buck-Boost bidirectional converter to drive piezoelectric actuators By GALCERAN ARELLANO Samuel; MONTESINOS MIRACLE Daniel; GOMIS BELLMUNT Oriol; SUDRIA ANDREU Antoni	[View] [Download]
Abstract: The present work deals with the development and control of a converter to drive piezoelectric actuators. In order to maximize the field in the piezoelectric ceramic important voltages are needed. To fulfill such requirements with a limited input voltage a bidirectional buck-boost converter is proposed. The converter is controlled by means of a sliding mode control strategy. The converter is validated by means of simulations.

	A MATHEMATICAL DESCRIPTION OF CONTROL METHOD ON THE BASIS OF DIFFERENCE CORRECTION By SKOVPEN Sergey; ISKHAKOV Albert	[View] [Download]
Abstract: In this paper, a mathematical description of the control method on the basis of difference correction applying to sampled-data systems is considered. The difference correction is an efficient way to improving the dynamic characteristics of the pulse power converters, which work is described by difference equations. Proposed method allows transforming a difference equation so that the roots of the characteristic equation become equal to zero. Herewith the maximum speed of convergence of transient to a steady value in the field of it's environ under perturbations of system parameters is achieved. Using the example of a system for stabilizing the load current of a buck converter it is shown that the transient is completed within two or three periods.

	A new method of adaptive predictive control in multimass electromechanical systems with variable parameters By PODBORSKY Pavel; KOLESNIKOV Artem; WINTERNHEIMER Stefan	[View] [Download]
Abstract: A method of synthesis adaptive locally-optimum control with predicting model for electromechanical systems with casual parameters is presented in detail. Thus for decision of a problem to estimate the changing parameters the theory of multilayered artificial neural networks methods are involved. The method is verified on a two-mass electromechanical systems with casual parameters.

	Accurate Sliding-Mode Control System Modeling for Buck Converters By HOYERBY Mikkel; ANDERSEN Michael	[View] [Download]
Abstract: This paper shows that classical sliding mode theory fails to correctly predict the output impedance of the highly useful sliding mode PID compensated buck converter. The reason for this is identified as the assumption of the sliding variable being held at zero during sliding mode, effectively modeling the hysteretic comparator as an infinite gain. Correct prediction of output impedance is shown to be enabled by the use of a more elaborate, finite-gain model of the hysteretic comparator, which takes the effects of time delay and finite switching frequency into account. The demonstrated modeling approach also predicts the self-oscillating switching action of the sliding-mode control system correctly. Analytical findings are verified by simulation as well as experimentally in a 10-30V/3A buck converter.

	An Online Control Strategy for a Modular DC Coupled Hybrid Power System By LINGEMANN Max; ORTJOHANN Egon; MORTON Danny; MOHD Alaa; OMARI Osama	[View] [Download]
Abstract: This paper describes how different power sources of a hybrid power system may be connected together through a DC bus and then to a grid through a main inverter in such a way that a decoupling between the state variables of the power sources and the state variables of the grid is achieved. A layout showing such a structure will be presented, and an online control strategy for this layout will be developed to show that it is modular, expandable and easily controllable. The behavior of such a structure under different load and meteorological conditions will be investigated by applying the developed control strategy to a simulation model. Moreover, a PV/battery hybrid power system was successfully built up including control functions for the system management. These control functions have been developed and integrated into a standard industrial soft PLC terminal. Finally, the results of the simulation and experimental case study will be introduced and discussed.

	Comparative Study of Two Predictive Direct Power Control Algorithms for Three-Phase AC/DC Converters By ANTONIEWICZ Patrycjusz; AURTENECHEA Sergio; RODRIGUEZ Miguel; KAZMIERKOWSKI Marian P.	[View] [Download]
Abstract: In this paper two predictive direct power control (P-DPC) algorithms developed by authors for a three-phase AC/DC converter are presented and compared. In the first, a variable switching frequency (VSF) algorithm, behavior of active and reactive power is predicted for all available voltage vectors generated by the AC/DC converter and the voltage vector which minimizes a cost function is selected for the next sampling period. The second, a constant switching frequency (CSF) algorithm, in every sampling period selects the voltage-vectors' sequences and computes their application instants in order to minimize tracking error of active- and reactive-power. Experimental results measured on 5 kVA laboratory AC/DC converter show performance of both P-DPC algorithms in stationary and transient states.

	Convergence Test of Model Reference Signal Adaptive SRM Drives By SZAMEL Laszlo	[View] [Download]
Abstract: Nowadays switched reluctance motor (SRM) drives have been widely used in the field of controlled electric motor drives. The paper proposes a model reference signal adaptive control method for SRM drives. The main goal of the drive control is to improve dynamical performance by compensating for the motor nonlinearities. The adaptation practically works only in a relatively narrow speed error track (adaptation range) which is equal to approximately 20-100 revolution/min absolute value of speed error. The drawback of this limitation is the relatively short time for the algorithm to operate. At the same time the convergence of the algorithm is extremely fast which significantly reduces the effect of this drawback. Two more important advantages emerge when adaptation works only with small speed errors. First of all the controller at changing drive parameters adapts to parameters around the value specified by speed reference signal which also assists to speed the adaptation. The other significant positive effect is the disappearing of the problem coming from nonlinear systems that the response of the system can even differ in its character when the value, amplitude of the reference signal is changed. The convergence test of this control method was performed in an experimental drive system. A SRM of 6/8 pole and 4 kW rated power was used. Simulation and experimental results are presented.

	Design of current controller in an AC drive using a state stimulator concept By LUKASIAK Przemyslaw; DĘBOWSKI Andrzej	[View] [Download]
Abstract: In the paper a new design method for finding the structure of the current controllers in electric drive on the example of an AC drive with induction motor is proposed. This method uses the approach based on the theory of dual-observers, proposed some years ago by D. G. Luenberger for improving the dynamic transients in the autonomous systems with the feedback loop. This approach was extended by one of the authors to the non-autonomous systems with external control. The modified dual-observer, being a special kind of state compensator, was called a "state stimulator". The method, described in this paper for indirectly controlled induction motor, can be used for design of current control loops in other kinds of electric drives as well.

	Friction compensation for a robust H∞-optimal position control of low order for a multi-mass system By JOOST Matthias; ORLIK Bernd	[View] [Download]
Abstract: Controlling a multi-mass system is a common problem in industrial automation. Varying or unknown parameters, especially friction, make the control problem more difficult. A powerful tool to control systems with uncertain parameters is a robust H∞-controller. Furthermore, high static friction often still causes problems like stick slip effects. Therefore, friction compensation is needed in addition to a robust controller. This paper will present a simple yet robust friction compensation used in tandem with a robust H∞-controller. Measurements will complete the paper.

	LOOP-SHAPING Hâˆž CONTROL FOR A DOUBLY FED INDUCTION MOTOR By SALLOUM George	[View] [Download]
Abstract: This paper deals with a Doubly Fed Induction Machine (DFIM) where both sides are supplied by two PWM inverters. The study consists in elaborating a robust vector control of the machine by the loop-shaping H∞ approach. The H∞ loop-shaping theory is presented in brief; then it is applied to the control of the DFIM. The simulation results prove that the implementation of the H∞ controllers for currents, fluxes and speed loops leads to excellent robustness in stability and good dynamic performance even with large electrical and mechanical parameters uncertainty.

	Maximum Torque/Minimum Flux Control of Interior Permanent Magnet Synchronous Motor Based on Magnetic Energy Model By TSUCHIYA Takeshi; TOSHIAKI Murata; TAKIGUCHI Masashi; TAMURA Junji	[View] [Download]
Abstract: This paper presents a field oriented direct torque control system in Interior Permanent Magnet Synchronous Motor (IPMSM) which controls torque to be the maximum and flux to be the minimum simultaneously. A PWM inverter-fed IPMSM control system has been driven by field oriented control algorithm without chattering by sliding mode control. The validity of the proposed method is confirmed by simulation results.

	Modified Sliding Mode Controller for Positioning of Micro Linear Motors By MERTENS Axel; DEMMIG Sven; WIEDMANN Karsten	[View] [Download]
Abstract: This paper reports on the control of micro linear motors using a modified sliding mode controller. To have an optimised dynamic behaviour the gradient of the sliding surface is calculated online instead of having a constant value. Simulations and measurements are presented to show the performance of the algorithm.

	Nonlinear adaptive control of a magnetic bearing By STAMANN Mario; SCHALLSCHMIDT Thomas; PALIS Stefan	[View] [Download]
Abstract: The presented paper shows how nonlinear adaptive control theory can be applied to magnetic bearings. Here the backstepping formalism is used to derive a stabilizing control law, which guarantees stability in the sense of Lyapunov in the presence of a unknown load. The efficiency of the proposed method comparing to linear standard design (e.g. PID) is demonstrated through experimental investigations.

	Robust performance of self-scheduled LPV control of doubly-fed induction generator in wind energy conversion systems By NGUYEN TIEN Hung; M.A. SCHERPEN Jacquelien; W. SCHERER Carsten	[View] [Download]
Abstract: This paper describes the design of a self-scheduled current controller for doubly-fed induction generators in wind energy conversion systems (WECS). The design is based on viewing the mechanical angular speed as an uncertain yet online measurable parameter and on subsuming the problem into the framework of linear parameter-varying (LPV) controller synthesis. An LPV controller is then synthesized to guarantee a bound on the worst-case energy gain for all admissible trajectories of rotor speed in the operating range. Furthermore, this study investigates the robust performance of the LPV controller with respect to other bounded machine parameter variations and the impact of the stator voltage dips on the robustness of the control system. Two closed loop simulation models, one with a conventional control scheme and the other with an LPV control scheme, are developed for the control of the electrical torque and the power factor on the rotor side in order to compare the performance of the control systems. Some simulation results are given to demonstrate the performance and robustness of the control algorithm.

	State Control of an Electromagnetic Guiding System for Ropeless Elevators By SCHMÃœLLING Benedikt; EFFING Oliver; HAMEYER Kay	[View] [Download]
Abstract: One major challenge in modern elevator construction is the design of systems, which satisfy the requirements of very high buildings. In this sense conventional elevators with mechanical guides came to their application limitations. An opportunity to optimize the passenger traffic in very high buildings and also in very deep mining applications is an elevator system driven by linear motors instead of traction sheave and ropes. This system can be improved by using non-contact electromagnetic guides instead of a conventional mechanical guiding system. The aim of this work is the implementation of a feedback control for such an active magnetic guiding system for an elevator car in a simulation model. At first, an overview over the applied elevator system is presented. Functionality of drive and guiding system is explained. Afterwards, the design of the simulation model and the derivation of a multi variable state control for the elevator car guiding are shown. Finally, results are presented and analyzed, which show the feasibility of the entire elevator system.