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EPE 1999 - Topic 04d: Converter Control - Application to Three Phase Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1999 - Conference > EPE 1999 - Topic 04: CONTROL > EPE 1999 - Topic 04d: Converter Control - Application to Three Phase Systems
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	A Comparison of Current Controllers for Three-Phase Four-Wire PWM Voltage Converters   By V. Soares; P. Verdelho	[View]   [Download]
Abstract: This paper presents a comparison of current controllers for the 3-Phase 4-Wire topologies based upon the 3- and 4-leg Voltage Source Converters. A phase coordinates current controller and space vector based current controllers are presented and compared. In order to compare the current control methods, performance parameters are established. Simulation results show the steady state operation of the current controllers and highlight their characteristics in terms of current errors and DC bus voltage utilisation.
	A Double 3-Level GTO Inverter Drive for High Performance Applications with Stator-Flux-Oriented Control   By M. Janßen; A. Steimel; X. Q. Wu	[View]   [Download]
Abstract: Two highly dynamic control schemes with very low torque ripple - Indirect Stator-Quantities Control and Track Length Control - suited for very high power induction motor drives fed by a double three-level GTO inverter are presented. The machine and inverter controls are explained, the excellent torque quality and dynamic is verified by measurements at a 180 kW drive.
	A Model-Based Dead-Time Compensation Scheme for a Voltage-Source PWM Inverter   By N. Hur; K. Nam	[View]   [Download]
Abstract: A current con troller having an inverse dynamic model and PI controller has been proposed with the aim of compensating the eects of dead time. The proposed con- trol sc heme, having t w o degrees of freedom (DOF), can be used for compensating the eects of disturbance without degrading trac king performance. T o be specic, the dis- turbance rejection property is enhanced by increasing the gains of a PI controller, but the PI gain does not aect the transfer function between the command and the output. By nature, it is robust to the parameter mismatch error between the model and the plant, since the mismatch error can be counted as another disturbance. With the experi- mental results, we ha ve sho wn the superiority of the pro- posed method in suppressing the current distortion caused by dead time.
	A New Pulse Modulation for Voltage Supply Inverter's Current Control   By J.C. Le Claire; S. Siala; J. Saillard; R. Le Doeuff	[View]   [Download]
Abstract: A new pulse modulation technique using current control for voltage supply inverters (VSI), based on an oscillator linked to a high speed current loop, offers excellent performance. This method can be used effectively for direct torque control (DTC) applications. For inductive loads, a hardware implementation of this method could replace a current hysteresis controller, thus improving control of an inverters maximum switching frequency.
	A Novel Fixed Switching Frequency Controller of a Three-Phase Volage Source Inverter   By A. Sarinana; S. Guffon; G. Bornard; S. Bacha	[View]   [Download]
Abstract: This paper proposes a new approach to control the main currents of a three-phase high power voltage source inverter (3ö-VSI) working as a reactive power compensator. Based on the direct sliding mode approach (DSMC) presented in [1], this controller directly provides the inverter’s switching configuration without the need of an intermediate look-up table or a PWM pattern generator. In that previous result, the inherent problem of high-switching frequency was tackled by using an hysteresis band. As it was pointed out, a drawback of that approach is that there is no a direct expression between the switching frequency and the hysteresis band and, in steady-state, a chaotictype behavior is observed due to the implementation of the control law. Borrowing some ideas of the space vector modulation technique (SVM), in this paper a novel DSMC working at a fixed switching frequency is proposed. Moreover, this approach produces, in steady state, well defined pseudo-limit cycles. Computer simulations are presented to confirm the effectiveness of the proposed control strategy.
	A Space Vector Control Strategy for Improvement of Control Speed and Reduction of Sensitivity of Phase Jumps   By T. W. Rasmussen	[View]   [Download]
Abstract: The paper describes a full space vector control strategy. The synchronisation is used to improve both the control speed of reactive power, and reduce the sensitivity to large phase jumps in the grid caused by switching large loads. The control strategy is tested with a 5-level 10 kvar laboratory model.
	A Vector Control Hysteresis Current Controller for Three Phase Loads   By E. Aldabas; J. L. Romeral; A. Arias; D. Bedford	[View]   [Download]
Abstract: This paper presents a new current regulator for three-phase loads based on orthogonal two-phase d-q as system. Voltage-source inverters having current controllers play an important role in a wide range of industrial systems, such as controlled ac drives, ac power supplies and active filters, where fast current control becomes a prerequisite. Standard solutions based on current regulators can be classified into three categories: hysteresis current controllers, ramp comparators controllers and predictive controllers. The authors present an Hysteresis Current Controller working in an orthogonal d-q system axis. From the error of the current and its derivatives, a new null-vector voltage application strategy has been developed to assure near constant lateral distance between the upper and lower reference limits. With appropriate control strategies, the resulting boundary error can be seen with a circular or square shape. Both regulators, circular and square error boundaries with and without null-vector voltage strategy, are developed here, analysed and digitally implemented using a high speed uP. Computer simulations and laboratory test were made in order to investigate the performance of the proposed regulators, and results showing properties of the different techniques have been discussed.
	A Vector Controlled Three-phase DC-Voltage Source   By M. Salo; H. Tuusa	[View]   [Download]
Abstract: Three-phase PWM rectifiers are becoming increasingly popular as the front-end converter unit in power electronic systems due to tighter EMC regulations. In this paper the three-phase current-type dc-voltage source with reactive power control is introduced. When the control system is realized in the supply-voltage-oriented reference frame the active (the dc-link voltage) and reactive power can be independently controlled with real and imaginary axis components of the supply current vector respectively. It is also shown that in synchronously rotating coordinates, where the sinusoidal variables appear as dc quantities, the compensation of the reactive power drawn by the supply filter can be done very easily. The proposed control system is realized using a single-chip Motorola MC68HC916Y1 microcontroller. Some experimental results are also shown.
	Algorithm Integration for Electrical Machine Drives   By P. Foussier; F. Calmon; J. Carrabina; M. Fathallah; V. Grennerat; X. Jordà; C. Gontrand; J. M. Rétif; J.-P. Chante	[View]   [Download]
Abstract: The paper deals with the integration of control algorithm for asynchronous motors using co-design methodology for mixed hardware/software implementation. The authors mainly focus on two points : the co-design flow and associated tools, a full hardware integration with programmable FPGA device. They also present the interest in using the CORDIC (COordinate Rotation DIgital Computer) algorithm as a mathematical processor. This study is part of project that investigates firstly, the codesign methodology in order to optimize the integration of control algorithms using hardware, software or mixed resources, and secondly the development of machine diagnosis routines.
	Application of Dual Kriging to Real Time DC Harmonic Distortion Minimization of Thyristor Converters under Unbalanced Voltage Supply   By E. Ngandui; G. olivier; G.-E. April	[View]   [Download]
Abstract: Thyristor converters are used in a wide variety of power system applications. they generate harmonics on both ac and dc sides. DC harmonic distortion drastically increases when the three-phase ac voltage system supplying the converter is unbalanced. An assymetrical firing angle technique for dc harmonic distortion minimization of thyristor converters under unbalanced voltage supply has been recently presented. However, the minimization technique requires the computation of some nonlinear transcendental equations, which are difficult to solve on-line by a microprocessor-based controller. In this paper an interpolation method known as dual kringing is used to obtain approximated compensation firing angles for the first order dc non-characteristic harmonics cancellation. Dual kringing interpolation procedures a set of analytical expressions, which approximate solutions to the transcendental equations. These equations can then be solved on-line in real time by a relatively low performance microprocessor. To verify the feasibility of the proposed method, a twelve-pulse ac/dc converter was assembled with a microcontrolled-based system. Simulations and experiemtnal results, which show the effectiveness of the proposed method, are presented.
	Averaged Model of the 3-Phase Inverter for Control Design   By B. Allard; H. Morel; X. Lin-Shi; J-M. Retif	[View]   [Download]
Abstract: Control design in the field of motor driving or traction, needs an accurate model of the converter behavior, but with a reasonable simulation cost. Moreover compared to nowadays practice, an important improvement may come with the use of non-linear averaged models, including an image of the converter non-linearities, like delays with respect to the driving, or the power losses. This paper presents an experience of a non-linear averaged model of a three phase static inverter which takes into account the non-linearities of semiconductor devices and topological parasitic components. A comparison between simulation and experimental results enables to discuss the validity of the proposed averaged model. Then an application of the non-linear averaged model is described in the field of current distortion compensation, on a 30kW workbench. Particularly, it is shown that it is reasonably possible to take care of the dead-time at the driving level instead as in the control loop itself. Our global approach renders possible to yield automatically an analytical averaged model of any static converter. Yet the analytical model may be used efficiently in control design, for example to improve on-line control quality.
	Comparative Analysis of Voltage Regulators Based on Thyristors and IGBT Switches Applied to AC Machines   By J. Lara; M. I. Guzmán; G. Panza; J. A. Restrepo; V. M. Guzmán; J. M. Aller	[View]   [Download]
Abstract: This work presents a comparative analysis of two AC voltage control techniques for induction machines, one using antiparalleled thyristor switches and the other one based on IGBT switches. this study defines the conditions to apply cach technique. Complete system performance is considered, including the AC machine, the electronic switches and the electronic power system. From the machine point of view, the analysis is focused on current harmonic content, harmonic torque effects, efficiency, speed control, soft start capability and power factor control. the electronic switches are studied, analyzing topologies, cost, reliability and controllability. the amount of harmonic pollution injected on the power system is also considered. The results point out that the controlled-switched scheme with IGBTs appears an effective, efficient and cost competitive alternative to the voltage regulation for AC machines.
	Compensation of Non Ideal Output Voltage Components From a 2-Level PWM VSI   By H. Bängtsson; M. Alakula	[View]   [Download]
Abstract: In a three phase VSI motor inverter a fundamental frequency harmonic current component will be found in the DC-link, due to position asymmetry. At sinusoidal PWM modulation a harmonic with 6 times the fundamental frequency will be found there, due to the dead time. This paper deals with reduction methods.
	Control of DC-Side Active Filter for 3-Phase Inverters in Aerospace Applications   By A. Cross; A. J. Forsyth	[View]   [Download]
Abstract: Low-order DC-link current harmonics result from unbalanced linear or non-linear three-phase inverter loads. In aerospace applications, large banks of electrolytic capacitors are unacceptable and alternative techniques must be used for filtering low-order harmonics from the DC-link. This paper describes the analysis and control of an active filter which requires no additional capacitance, and which may eliminate selected, variable DC-link current harmonics. Experimental results demonstrate the system operation.
	DiCoIF: a DTC Strategy with Imposed Switching Frequency for Multi-Cell VSI fed Induction Motor Control   By C. A. Martins; X. Roboam; T. A. Meynard; A. S. Carvalho	[View]   [Download]
Abstract: This paper presents a new strategy of Direct Torque Control (DTC) of an induction motor fed by a three phase multi-cell voltage-source inverter (VSI). This strategy is generalized regarding the inverter number of cells (levels), and allows operation of the inverter under quasi-constant switching frequency, independently on shaft speed and load torque. The control algorithm is divided into three hierarchical units (space vector selection; reference phase levels selection; switching cell selection), each one exploiting a particular type of degrees of freedom. Simulation results are presented for comparison of both DiCoIF strategy with three-cell (four levels) VSI, and the classical DTC strategy with two-levels VSI, regarding frequency deviation, torque ripple magnitude and transient torque response.
	Dynamically Reconfigurable Architecture Dedicated to the Test of PWM Algorithms   By E. Monmasson; H. Echelard; J. P. Louis	[View]   [Download]
Abstract: In this paper the authors present a versatile Architecture dedicated to the test of PWM Algorithms in order to control three-phase Inverter. This realization based on FPGA's allows the implementation of a large variety of PWM strategies. But the most interesting feature of this test board is its in-system operation reconfiguration property.
	Equivalence of Fuzzy and Classical Controllers: An Approach to Fuzzy Control Design   By Z.H. Akpolat; G. M. Asher; J. C. Clare	[View]   [Download]
Abstract: This paper addresses the fact that any linear discrete classical controller, applied to control of a machine drive system, can be exactly represented by a fuzzy controller. This equivalence is then used as a method for designing both Sugeno and Mamdani type fuzzy controllers for systems with known non-linearity over its operational region. Simulation and experimental results are given for three examples-including a variable inertial load, showing the effectiveness of the design approach.
	Experimental Passivity-Based Adaptive Control of a 3-Phase VSI   By E. Oyarbide; S. Bacha	[View]   [Download]
Abstract: The present paper deals with a recent control technique in the power electronics field: the passive control. Some theoretical issues of this control are reviewed and a robust performance strategy is developed. Simulation and practical results are compared, and robust behavior versus line voltage variation is experimentally tested.
	Frequency Converter With Minimized DC-Link Capacity   By H. Raffel; O. Scheuer; B. Orlik	[View]   [Download]
Abstract: This paper deals with an optimized topology of a frequency converter. Using a high dynamic control method for a line side pulse converter, a constant dc-link voltage and an adjustable power factor is ensured even if the dc-link capacitor is reduced by an order of magnitude. therefore a special control strategy is necessary to improve the performance of the converter, such as the state-space analysis. Finally, the controller design is verified in terms of simulations and practical measurements.
	Fuzzy Logic Based Control for Power Electronics - A Case Study   By A. Martins; A. S. Carvalho	[View]   [Download]
Abstract: Power electronics processes are usually complex and multivariable ones. The application of digital multivariable controllers in such processes is difficult due to practical limitations in memory space and processing time. Multi-input/multi-output fuzzy controllers allow the inclusion of different types of knowledge about the controlled process, namely the use of a hierarchical architecture. This allows an important reduction in the controller dimension. The paper presents simulation and experimental results based on the application of two developed controller types in the supervision of the parallel operation of UPSs. In fact, the implementation of MIMO controllers based on the presented approach shows to be very performant.
	Improved Switching Method for AC-DC Converters   By V. Racek; L. Cesnak; V. Zemanek	[View]   [Download]
Abstract: High power factor and low harmonics distortion on AC lines and not rippled current on DC line are required in today's 3 phase AC-DC converters. This paper presents how to increase performance of the converters with a new switching method based on PWM strategy. The control of the power switches is realised with a RISC micro controller at ultrasonic frequencies with respectable efficiency.
	Improvement Possibilities of PWM voltage Inverter EMI Effects Using Different Modulation Methods   By D. Gonzalez; J. L. Iaquet; A. Arias; D. Bedford; J. L. Romeral; J. Balcells	[View]   [Download]
Abstract: A problem presented by the drives is the circulation of Common Mode (CM) currents through stray capacitances of the load. This currents may damage the ball bearings and degrade the isolation of the motor. Unwanted firing of earth leakage relays can be originated by these currents. In order to improve the EMI effects on the load side over a specific range of frequencies some modulation techniques for three-phase voltage source inverters have been reported. In this paper, the experimental results about EMI effects of one of this modulation techniques are described and compared with a classical vector modulation. the main EMI effect on the load side is the circulation of CM currents. Conclusions about the improvement possibilities of the load side CM EMI effects are obtained from the results.
	Interactions Between Dead-Beat Controlled Rectifiers and Input Filters   By P. Mattavelli; S. Buso	[View]   [Download]
Abstract: The paper analyses the stability limitations of the digital dead-beat current control applied to voltage-fed three-phase converters used as PWM rectifiers. In particular, attention is focused on the interactions between the rectifier and the input filters, which are commonly employed to eliminate the high frequency harmonic content from the line currents. The effects of the inherent model mismatch represented by the input filters, which are not normally included in the conventional dead-beat algorithm, are analysed by developing a detailed stability analysis, based on a discrete-time state space model of the controlled system. The proposed analysis allows to predict the occurrence of unstable conditions and to identify some control refinements improving the system's robustness. The results of the theoretical analysis and the validity of the proposed modifications to the control strategy are finally verified by simulations.
	Methods of Control for Three Phase PWM Step-up Rectifier connected to an Assymetrical Supply   By C. B. de Visser; S. W. H. de Haan; P. Bauer; R. Schoevaars	[View]   [Download]
Abstract: Two control algorithms are proposed for controlling a PWM step-up rectifier that is connected to an asymmetrical grid: a feedforward and a feedback controller. Both methods are compared to a standard symmetrical control method. The control objective is to maintain a constant output power, regardless of the asymmetry in the grid. The quality of the input currents has to be optimised, which means an optimised power factor. The theoretical basis for a controller with such characteristics is the instantaneous power theory. Simulations show that the proposed asymmetrical feedforward control reduces the ripple on the output power considerably, however, the output voltage gets an offset value due to a time delay and discrete time effects caused by the data processing, respectively, the digital controller. The simulation results for the feedback controller are promising: a large asymmetry up to 25% in the power supply can be handled by the feedback controller and yields an output power variation of about 4%, depending on the capacitor size.
	Modelling and Control of Three-Phase VSR with Buck-Boost Operation   By S. Fukuda; T. Ito	[View]   [Download]
Abstract: A rectifier system having a voltage step-up and step-down characteristic is treated. The system consists of a PWM voltage source rectifier and a dc-to-dc buck converter connected in the cascade. Linearized state equation which governs the whole system is presented. An optimal regulator is applied to control the rectifier system. Validity of the modelling and control strategy is confirmed by simulation studies.
	Modularized Communication and Control Architecture for Power Converters   By I. Milosavljevic; D. Borojevic; I. Celanovic	[View]   [Download]
Abstract: Control structure of today's digitally controlled power converters does not fully utilize benefits of digital communication. This paper proposes a new modularized control structure, defines communication requirements and presents a new high-speed digital control network, with synchronization capabilities, that is more appropriate for these systems.
	New Concept of Controller for the Control of Alternative Quantities   By X. Guillaud; F. Vandecasteele; M. Wulverick; J.P. Hautier	[View]   [Download]
Abstract: A lot of power electronic systems need the control of alternative quantities. The introduction of resonant element in correctors is a well-suited solution to achieve this function. Indeed, the loop gain is infinite at resonance frequency so the disturbances of same frequencies are cancelled out and a sinusoidal reference is perfectly tracked. In order to apply this concept in variable speed drive of electrical machines, the resonance frequency might be adapted to these of the current references. Experimental results on an asymmetrical induction motor confirm this assertion. This idea is then extended to multifrequency resonant corrector.
	Parameter Design of a State-Variable Controller for PWM Voltage Source Converters Connected to the Grid   By D. Sharon; A. Rufer	[View]   [Download]
Abstract: Controlled pulse-width modulated (PWM) voltage source converters (VSC's) are increasingly used in power systems for active filtering of line current harmonics and reactive power compensation. In this paper the parameter design of a state variable controller to determine the instantaneous switching pattern of the converter switches for otimal dynamic system performance is discussed. To this end the mathematical model of a system encompassing a three phase system grid and a VSC converter controlled by a state variable controller is developed. The space vector approach is used. Simulation results confirm the theoretical expectations.
	Robust Pre-established Settings for PID-like Fuzzy Logic Controllers   By D. Hissel; P. Maussion; J. Faucher	[View]   [Download]
Abstract: This paper describes a robust and simple on-site experimental tuning method for PID-like fuzzy logic controllers. A set of robust pre-established settings, obtained using a three-dimensional adaptation of Taguchi’s quality design methodology and depending only on one preliminary open-loop identification test is here provided. Satisfying experimental results obtained on a DC/DC Buck converter and a permanent magnet synchronous motor are provided.
	Sensorless Vector-Controlled Induction Motor Drives Using Random Switching Technique   By Y-S. Lai	[View]   [Download]
Abstract: It has been demonstrated in some publications that the advantages of random inverter switching techniques for drive applications include the reduction of acoustic noise, vibration and conducted electromagnetic interference. However, for the inverter controlled by the randon switching techniques as demonstrated in another publication, it is required to adjust the gains of current controllers in every sampling interval if the current controllers operate with a variable sampling interval synchronized with the switching interval of the inverter controller. The reason for this result is that the sampling frequency of the random inverter switching techniques is not regular. In this paper, it is intended to show the newly developed random switching technique which does not invoke any change to the sampling processes, can be easily applied to inverter control in a vector-controlled drive. Therefore, it is demonstrated that the new random switching technique can be an alternative choice for inverter control in a microprocessor-controlled drive system, without requiring to adjust the gains of current controllers in every sampling interval. Experimental resulmts derived from a sensorless induction motor drive using a digital signal processor (DSP) as the controller will be presented. the features of the new random switching technique will be highlighted by these experimental results.
	Some New Fuzzy Control Strategies in an Induction Machine Position Servo System with Nonlinear Load   By Z. Wu; D. Naunin	[View]   [Download]
Abstract: In this paper some novel fuzzy control approaches are developed for an induction machine position servo system with nonlinear load. A new fuzzy flux observer is developed to obtain the information of flux. The parameter of the flux observer is optimized with the help of Kalman-Filter technique. The model based fuzzy control method is employed to design the current controller. Fuzzy- Modelling approach is employed to model the nonlinear load conditions, then a generalized predictive control on the basis of the fuzzy model provides an on-line optimized control law. Both simulation and experimental results verified the novel fuzzy control approaches: quick position response without overshoot has been realized.
	VSC Connected to the Grid - Transformation Angle Impact on Performance   By J. Svensson	[View]   [Download]
Abstract: A grid-connected voltage source converter using sub-oscillation PWM and a discrete vector-current controller is investigated. The paper fucusses on how an offset in the transformation angle influences the control performance in the small-signal scheme. The direct couplings are almost not affected at all. For the direct couplings, the gain is constant independently of the value of the offset angle. But the gains of the cross-couplings increase when the absolute value of offset angle increases. The couplings of the grid voltages to the currents do not become affected at all for the offset angle.