doc. Ing. Jan Bauer, Ph.D.

Slip controllers are crucial for railway vehicle operation when a high tractive effort is required. The slip controllers have been developed for decades, and their developments continue. The developed slip controllers are based on many more or less effective principles. One of the perspective slip controllers determines a phase shift between an injected excitation signal to the required torque of the electric drive and the signal representation in a measured wheel angular velocity. The slip controllers that are based on the principle can effectively work with any adhesion conditions. However, the slip controller principle has some drawbacks like high filtration requirements, possible failure due to mechanical shock in the wheel-rail contact and long response time. The paper proposes a novel phase shift detection method for the slip controller based on an unscented Kalman filter that can cope with the known disadvantages of the original slip controller. When the proper output of the UKF is used, the slip controller becomes faster, more reliable and can work when the original slip controller fails. The proposed slip controller was verified on the measured data in an open-loop calculation and the mathematical model in the closed-loop simulation.

Locomotives are equipped with slip controllers that improve their adhesion utilization and keep wheels slip velocities at appropriate values. The current slip controllers typically correctly work during the regular train run. However, there are some cases when some slip controllers may fail. The correct operation at low velocities is one of the cases in which the slip controller can fail. The long-time response of the velocity measurement that is caused by incremental encoders with a low number of pulses per revolution is causing the problem in this case. The wheel slippage can occur when the adhesion conditions are adverse, and applied forces are high in this case. This paper describes a novel slip controller based on the unscented Kalman filter that correctly works during the train low velocity operation with any adhesion conditions. The slip controller was designed with taking into account all aspects that influence the controller operation. Therefore, the adhesion, electric drive, the slip controller, and problem background are described in the paper. The slip controller functionality is verified on measured data and a mathematical model that was verified on the measured data.

The current and torque ripple of inverter-fed induction motor drives is an inherent problem of control strategies working with switching frequencies in the range of multiple kilohertz, such as direct torque and, more recently, predictive torque control. If the drive operates in a wide-speed and wide-torque range and is equipped with a machine with an accessible terminal block whose winding is nominally connected in delta, then the current and torque ripple can be reduced by utilizing the delta-star winding changeover technique. When the winding configuration is switched from delta to star, the instantaneous motor phase voltage peak is lowered, and its total harmonic distortion is reduced. However, the control strategy must be adjusted according to the actual winding topology, mainly due to the difference in the coordinate transformations of the measured currents and the difference between the phase voltage vectors obtained from the inverter. This paper proposes a predictive torque control of an induction motor drive with a switchable delta-star winding configuration. The paper is supported by theoretical background, and the key idea is verified by simulations in MATLAB/Simulink and experiments conducted on a dSPACE-controlled 5.5-kW laboratory drive. The simulations validated the presented equations and show the effects of not respecting the actual winding topology. The experiments mainly focused on analyzing the total harmonic distortion of the currents and consumed electrical power in multiple operating points.

Mathematical models of induction motor (IM) used in direct field‑oriented control (DFOC) strategies are characterized by parametrization resulting from the IM equivalent circuit and model‑type selection. The parameter inaccuracy causes DFOC detuning, which deteriorates the drive performance. Therefore, many methods for parameter adaptation were developed in the literature. One class of algorithms, popular due to their simplicity, includes estimators based on the model reference adaptive system (MRAS). Their main disadvantage is the dependence on other machines’ parameters. However, although typically not considered in the respective literature, there are other aspects that impair the performance of the MRAS estimators. These include, but are not limited to, the nonlinear phenomenon of iron losses, the effect of necessary discretization of the algorithms and selection of the sampling time, and the influence of the supply inverter nonlinear behavior. Therefore, this paper aims to study the effect of the above-mentioned negative aspects on the performance of selected MRAS estimators: active and reactive power MRAS for the stator and rotor resistance estimation. Furthermore, improved reduced‑order models and MRAS estimators that consider the iron loss phenomenon are also presented to examine the iron loss influence. Another merit of this paper is that it shows clearly and in one place how DFOC, with the included effect of iron losses and inverter nonlinearities, can be modeled using simulation tools. The modeling of the IM and DFOC takes place in MATLAB/Simulink environment.

Although still widely used due to its robustness, reliability, and low cost, induction motor (IM) has a disadvantage of more complicated mathematical description than permanent magnet AC machines. In high-demanding applications, the decoupled control of the machine’s flux and torque along with the proper function of selected efficiency-improving and flux-weakening algorithms can be achieved only if the IM parameters are known with sufficient accuracy. For parameter estimation, many algorithms have been proposed in the literature so far. Due to its simple and straightforward implementation, one of the popular estimation strategies is the model reference adaptive system (MRAS). However, MRAS-based algorithms for a specific parameter estimation tend to be sensitive to other machine parameters. For instance, most of the proposed MRAS algorithms do not consider the influence of the phenomena such as iron losses and load-dependent saturation. Since one of the most performance-decisive parameters of the popular rotor flux-oriented control (RFOC) are the magnetizing inductance and the rotor resistance, this paper aims to present a novel MRAS-based magnetizing inductance estimator (Lm-MRAS) with the included effect of iron losses. Furthermore, to enable the identification of the load-dependent saturation, another MRAS with included iron losses based on reactive power is proposed to work parallelly with Lm-MRAS, since under load conditions, the rotor resistance mismatch causes RFOC detuning. The adaptation law of the Lm-MRAS is obtained using the Lyapunov function approach and further examined using small-signal analysis. The proposed algorithms are verified on a 3.6 kW IM drive both in simulations and experiments.

DC current component in the power grid may cause gross measurement errors and lead to overheating of power transformers. We have previously developed method how to measure DC current using fluxgate effect in existing current transformers. In this paper we show that using ferroresonance the power consumption of such device can be drastically reduced. The microprocessor can both control the H-bridge excitation unit and perform signal processing, avoiding the need of external instruments.

Today’s modern control strategies of an induction motor (IM) drive require a power source with an adjustable output voltage frequency and amplitude. The most commonly used converter topology is a two-level voltage-source inverter (VSI). However, the utilization of a VSI introduces additional voltage and current distortion, which leads to additional power losses in the machine’s magnetic circuit. Both the transistor switching frequency and the type of the inverter control determine the total harmonic distortion (THD) of the motor’s phase currents. In this paper, the influence of the inverter DC-link voltage on the iron losses of an IM controlled by a predictive torque control (PTC) is presented. It is shown that if the IM drive operates below the rated speed, it is possible to modify the PTC algorithm to reduce the additional iron losses caused by the non-harmonic inverter output voltage. The control of the DC-link voltage is achieved by using a silicon-controlled rectifier. Experiments were conducted on a 5.5 kW IM controlled by PTC, and the results are compared against a sinusoidal voltage supply created by a synchronous generator.

Accurate knowledge of induction machine parameters has a direct impact on the overall performance of field-oriented control strategies. In the case of rotor flux oriented control, parameter mismatch causes a discrepancy in the estimated rotor flux position and amplitude. Magnetising inductance is one of the parameters whose detuning has a direct impact on the setpoints of the control loops and estimation of hardly or non-measurable quantities. Conventional iron saturation, which can be obtained by a standard no-load test, is not the only type of saturation occurring in the machine. Depending on the rotor design, the magnetising inductance and the rotor leakage inductance may also strongly saturate as a function of load and, thus, rotor current. Based on our previous work, a new, improved experimental method for identifying the load-dependent saturation of induction motor, which takes into account variation of the inverse rotor time constant, is proposed. Experimental results conducted on 12 kW motor show improved static and dynamic behaviour of the drive compared to the constant parameter model.

Omission of the speed sensor in induction motor based electric drive is very actual topic because of cost savings. When omitting the speed sensor, induction machine mathematical model that does not require information about rotor speed has to be used, such as voltage model. The quality of control then depends on the model stability and accuracy of induction motor parameter identification. This paper strives to discuss most important quantities that influence stability and accuracy of the voltage model.

This work deals with a real-time optimum flux search control (SC). The method is integrated into Predictive Torque Control (PTC) of induction motor drive (IMD). The proposed predictive search control searches the optimum stator flux amplitude, at which the current amplitude is the lowest. The output of the SC is used as a reference for the PTC controller. As the control variable of the proposed SC, the predicted stator current vector amplitude is utilized. The method was verified experimentally on a laboratory drive with a 5.5 kW induction motor. The IMD achieves a current minimization while maintains the working point defined by the speed and load. The experiment shows good results during steady-state and sufficient performance during transients.

This paper proposes a new method leading to a reduction in the current and torque ripple of an Induction Motor (IM) drive controlled by a Predictive Torque Control (PTC). The method lies within the optimisation of DC-link voltage magnitude by a three-phase thyristor bridge rectifier. Using a controlled rectifier, the DC-link voltage can be adjusted in such way that the ripple of the IM state variables, caused mainly by treating the inverter as a source of only eight voltage vectors, is significantly reduced. Another positive consequence of the proposed algorithm is the reduction of DC-link-dependent switching losses. The DC-link optimisation algorithm is integrated within the PTC that is used for the torque and flux control. The theoretical analysis of the DC-link voltage influence on the drive behaviour is supported by simulation and experimental results conducted on a 5.5 kW IM drive, which confirms the benefits of the PTC with the DC-link voltage optimisation.

Many algorithms of induction motor sensorless control need accurate knowledge of the stator voltage vector. However, the machine is in most cases supplied by a two-level voltage-source inverter; therefore, the voltage is distorted by the inserted dead-time and also by nonlinearities of the semiconductor switches. This paper analyzes a distortion caused by the dead-time and delayed IGBT switching in terms of distorting voltage vector. An offline measurement is performed to obtain the inverter model. Then, an analysis of two simple volt-seconds-based compensation methods (compensation of the reference voltage vector and duty cycle, respectively) on the accuracy of the speed estimation of a sensorless field-oriented control based on the rotor flux model reference adaptive system is performed. The analyzed methods use either the full inverter model implemented as a look-up table or its trapezoidal approximation. Outline on computational complexity and discussion on finding optimal coefficients for the trapezoidal model are given, too.

Jedna z možných a výpočetně poměrně nenáročných metod bezsenzorového vyhodnocování otáček asyn-chronního motoru je adaptivní systém s referenčním modelem (angl. Model Reference Adaptive System - MRAS) založený na rotorovém toku. V rámci této strategie jsou paralelně vyhodnocovány proudový a napě-ťový model asynchronního motoru. Stabilita a přesnost celého řízení se pak odvíjí od stability a přesnosti obou modelů. Do napěťového modelu vstupuje statorové napětí, které je však tvořené pulzy zkreslenými ochrannými mrtvými dobami a nelineárním chováním střídače. Tento článek představuje jednoduchou a snadno implementovatelnou metodu pro identifikaci a kompenzaci zkreslení ochrannými dobami a zpoždě-ným spínáním IGBT tranzistorů. Součástí článku jsou výsledky experimentálního ověření na 12kW motoru.

The simplest mathematical models of the induction motor (IM) use the presumption of the machine’s linear magnetising characteristics. However, this may hold only in a limited operating range of the electric drive. It is well known that the magnetising inductance saturates as a function of the magnetising current due to the nonlinear properties of the magnetic circuit. However, this is not the only type of saturation. Depending on the design of the rotor, the machine’s magnetising and leakage inductances may also saturate as a function of the rotor current. A new experimental method is proposed in this paper. It identifies the dependence of the T equivalent circuit magnetising inductance on the rotor flux and torque producing current component using parallel operation of the so-called current and voltage model of the IM.

The accuracy of induction motor (IM) drive with employed field-oriented control depends on precise identification of the IM equivalent circuit parameters. Those parameters can change significantly during the drive operation. Therefore, an adaptation of the IM model parameters is needed for a high-performance drive. Estimators based on model reference adaptive system (MRAS) are not computationally demanding, but they a priori exhibit sensitivity to the other, non-estimated parameters. This paper analyses the influence of the proper knowledge of the magnetizing inductance on the accuracy of the rotor resistance estimator based on the traditional reactive power MRAS. The paper also takes into account the load-dependent saturation of the IM, which is often omitted during the analysis and shows that the implemented load-dependent magnetization characteristic improves the MRAS and drive performance. Simulation and experimental results conducted on 12 kW IM are presented.

Important parameters of an induction motor drives include dynamics and efficiency. Both attributes are tightly associated with accurate acquisition of hardly measurable quantities such as magnetic flux (and its position) and motor torque. The mathematical model of the induction machine is used for calculation of these quantities. The model usually comprises of a set of differential equations, that have to be numerically solved inside drive's controller. Computation time requirement and accuracy of the resulting estimation are important parameters of the selected solver. For this purpose, Euler's method was usually used in engineering applications, but with increasing computational throughput of DSP, more complicated numerical methods can be applied too. This paper strives to compare Euler's method with 4 th order Runge-Kutta method.

Most of the railway traction vehicles are moved thanks to the transfer of traction, braking force by small contact area between wheels and rail (steal to steal contact). The ability of force transfer by contact area or also the sum of the contact area physical properties is called adhesion. In order to utilize maximum transferable force, a slip controller has to be added into drive control structure. The paper studies possibility of the Model Predictive Control (MPC) strategy application to support the slip controller function. The considered slip controller is based on the speed and current response of the torque reference signal injection. Therefore, the controller requires high torque control accuracy. Results of MPC are compared with the Direct Torque Control (DTC) strategy that is often used for control of high power drives with induction motor (IM).

The induction machine operated as generator can be a very valuable alternative to the synchronous machines. Mostly in applications with lower nominal power ratings. In this case it can be more cost effective. Disadvantageous is a fact that induction machine cannot generate a reactive power and even more it is a permanent consumer of the reactive power. This paper strives to analyze possible application of direct AC to AC converter to increase application range.

This paper describes influence real semiconductor devices, commutation strategies, modulation period selection and switch on resp. switch off times on output voltage of matrix converter. Methods for decreasing of the influence are mentioned in the paper too.

In this paper is described method of realization of rotor flux oriented control of the induction machine fed by matrix converter with current control. Matrix converter belongs to the category of direct frequency converters that produce output voltage by the means of direct switching of proper input phase voltage to the output. This fact can introduce some problems into control algorithm compared to drive fed by conventional voltage source inverter.

Current transformers (CTs) show large errors when they are magnetized by dc current. This error can be reduced after proper demagnetization. One of the methods to demagnetize the CT is to increase the core flux by increasing its burden. The burden should be adjusted according to the measured ac current. In this paper, we show that pulsewidth modulation switchable resistor can be used as variable burden for this application. This method enables to restore the nominal precision of the heavily magnetized CT from 2.5% back to 0.2% without interruption of the CT operation.

The presented paper summarizes the approaches to dynamic description of an induction machine and presents them from the view point of the modern theory of dynamic systems. Great impact has the selection of the particular state variables. It decides about the mutual dependency of calculated values. Despite of the fact that it is still a correct description of the same system, it in°uences the design of control structures. Only the matrix form underlines clearly the particular differences and shows what combinations of state variables are eligible to be employed in hierarchical control structures.

Compared matrix converter with indirect frequency converter, the lacking DC-link accumulation element is its cardinal advantage in terms of volume and weight. On the other hand, in case of matrix converter the control system is much more complex. In the design of matrix converter switching pulse sequence generation the complicated IGBT's commutation process as well as modern sophisticated modulation strategies must be taken into account. System reliability is dependent on the selected commutation algorithm and the proposed modulation strategy significantly affects the maximal reachable output voltage amplitude and thus the whole connected drive dynamics. Times of commutation, semiconductor device minimal switch-on and switch-off times play the essential role, too

The induction machine in the operating mode of generator is a very valuable alternative to the synchronous machines. Especially in lower nominal power rating range, such solution can be more cost effective. Induction machine with a squirrel-cage rotor cannot generate a reactive power and even more it is a permanent consumer of the reactive power. In this paper, we strive to define theoretical limits of operation if the electronic source of reactive power is used.

Simulation is nowadays common way how to develop and test control algorithm of a drive before its run up on the real converter. The main problem is that because the control algorithm of the drive has to run in real time and it usually calculates and then outputs switching commands for the transistors, debugging and stopping of the algorithm execution is not possible. Therefore the developed code has to be tested in another way before putting to the real controller. This paper describes development and testing of FOC algorithm for IM drive fed by matrix converter.

– This paper describes a embedded controller for the matrix converter. Thanks to its computing throughput it is suitable for university use, but it enables operation in the whole industrial rage thank to its construction. Besides the example usage in matrix converter, the control system is generally usable for various control tasks.

Two types of dielectric barrier discharge (DBD) powering principles were compared in this study. The variable autotransformer (sinusoidal shaped voltage) and the semiconductor H-bridge converter generating pulse width modulation (PWM, square wave shaped voltage) were used as a voltage source. Differences were found in the discharge current waveforms. Powering the DBD by PWM provides promising features for plasma application.

The rotor resistance can change significantly depending on the mode of operation of the induction motor. It can influence the accuracy of the controller. This paper strives to analyze if it is important to respect the resistance change or not.

Similarly as in field of combustion engines the efficiency map is very convenient tool for comparison of different motor variants. The overall efficiency of the induction machine can be analyzed in this way too. It is well known, that behavior of the induction machine can be easily described by its state space model. However, this description is mostly used in order to analyze the dynamic behavior only. The efficiency of the machine remains mostly out of the scope of the published articles. Moreover, the rotor resistance can change significantly depending on the mode of operation of the induction motor and power loss caused by hysteresis and eddy currents is not included into the consideration at all. Therefore this paper strives first to derive analytically the efficiency of the induction machine and thus prepare the comparison basis for the future impact analysis of changing the machine parameters and respecting the power loss in magnetic yoke.

Návrh a realizace měřicího systéme na bázi PXI National Instruments. Vytvoření zkušebního software pro měření a následné vyhodnocení naměřených dat. Sestavení matematického modelu slučující výsledky měření a potřeb systému Matlab. Ověření naměřených charakteristik typového protokolu s výslednými grafy matematického modelu v systému Matlab.

This contribution strives to compare behaviors of the IM drive controlled by classical DTC and modified direct torque control strategy based on state space variable description of the IM and first order sliding mode controller. Simulations on SW Matlab/Simulink were carried out to test proposed control strategy and compare them with model of ST-DTC.

Modern electric drive can be comprehended as electro mechanic energy changer. The own change of electric energy to the mechanic energy is done by the electric motor. It needs for the demanded conversion proper voltage, currents or frequency on its terminals. In case of higher demands, like high dynamics of the motor is required, the converter is usually connected in front of the motor. Due to their robustness and durability recently induction machines are used in modern regulated drives. To gain maximal performance from the induction machine is the research also focused on the so called all silicon converter solutions like matrix converter. From the point of control algorithm the the Direct Torque Control (DTC) is one of the most common high performance induction motor control methods nowadays. This paper compares two modern controller approaches for realization of DTC IM drive fed by matrix converter

V dnešní době, kdy se čím dál víc začínají rozšiřovat vozidla s kombinací spalovacího motoru a elektromoto-ru začíná být i účinnost elektromotoru důležitým faktorem z hlediska množství spotřebované energie z baterií. Protože účinnost elektromotoru závisí na jeho provozním stavu (tok, moment, otáčky) je potřeba tyto veličiny vzít v potaz při návrhu regulátoru. Tento příspěvek se zabývá možnostmi analytického výpočtu účinnosti na základě naměřených parametrů náhradního schématu motoru

The matrix converter is a very popular topic because of its advantages in comparison with the indirect frequency converter [1]. The modulation strategy and control algorithm used are very important parts of the converter’s controller. Recently modulation strategies based on a virtual DC-link space vector modulation are used, which works as a dependency injection [2]. That is why different approaches can be used to control both the output voltage and the input current at the same time. In this paper phase control of the input current in combination with a machine’s torque fuzzy controller is presented. This enables us to overcome the traditional limitations of the output voltage without resigning from the input current control.

This paper presents the using of dSpace DS1103 for the electric vehicle power consumption modeling. The dSpace is a part of control system where the main controller is an embedded module G400-D from the GHI Electronics company. The G400-D module communicates with a GPS receiver used for the actual point on the known track showing.

This paper examines the problem of adequacy in induction machine modeling and attempts to provide a firmer basis for the selection of an appropriate model, to find a possible connection between the two most widespread models and to confirm or disprove their equivalence or differentness as the case may be.

Nowadays in variable speed drives induction machines are widely used. For the understanding and clear specifica-tion of the electromagnetic processes in the induction ma-chines different equivalent circuits can be employed. Traditionally, in order to reduce the complexity of the mathematical model the resistances and inductances are represented as concentrated components and 3 phase wind-ing is assumed to be symmetrical. These equivalent circuits are also used as a starting point for the design of the drive controller. This article strives to compare the two most widely used models and to derive a transformation against each other. In most papers that deal with the problematic of the IM drive control, equation based on the Park's transformation as a T-formed equivalent circuit are used. These models are adequate in many situations. Even though they can seem to be overly simplified, they can serve as a solid basis for an advanced motor control. However other authors tend to use gamma models and there are approaches using both. This paper examines and compares some of the issues of ade-quate machine modeling and attempts to provide a firmer basis for selection of an appropriate model and to confirm or disprove the equivalence of different approaches.

The algorithms based on separated control of the motor flux and torque are used in order to gain the maximum performance from the induction machine. To push the efficiency and dynamics limits of the IM to its limits mostly FOC or DTC control strategies are used. Both are based on the knowledge of the hardly measurable variable-machine flux. To obtain the information about inner machine flux models based on the machine equivalent circuit are mostly used. Therefore the accuracy of the equivalent circuits has direct influence on the accuracy of the machine control. To reduce the complexity of the mathematical model the resistances and inductances are concentrated to one component and 3 phase winding is assumed to be symmetrical. In order to design control strategy for the induction motor, system equations and equivalent circuit must be established at first. This paper examines and compares some of the issues of adequate machine modeling and attempts to provide a firmer basis for selection of an appropriate model and to confirm or disprove the equivalence of different approaches. The results of the IM model run up are then compared to the results obtained from the measurements on the real machine and the equivalency is discussed.

Nowadays in variable speed drives induction machines are widely used. For the understanding and clear specification of the electromagnetic processes in the induction machines different equivalent circuits can be employed. Traditionally, in order to reduce the complexity of the mathematical model the resistances and inductances are represented as concentrated components and 3 phase winding is assumed to be symmetrical. These equivalent circuits are also used as a starting point for the design of the drive controller. This article strives to compare the two most widely used models and to derive a transformation against each other.

The continuous popularity of the research in the area of the matrix converter control theory has been supported by steady technological improvements. It is still common to use discrete semiconductor switches in an anti-serial connection, even though some integrated solutions have been presented by various vendors already. Furthermore, recently experimental all-in-one matrix converter power modules based on reverse blocking transistors were introduced. However, this development has not eliminated the need of the protection circuit and other passive components in the converter's power part. This article strives to describe design procedure for one kind of the matrix converter protection circuits and the design of the input filter for the 3x3 matrix converter prototype.

The paper focuses on design and simulation of the low power inverter for photovoltaic application. In the paper it is briefly discussed the DC/DC converter design for the tracking MPP of the solar array and then the design of the control algorithm for the output inverter is discussed. Both possible operation modes - work in “island mode” and operation in the supply grid are considered and a control algorithms for them were developed and simulated. Attention is also paid to the design of the output filter for the converter

The matrix converter is a very popular topic because of its advantages in comparison with the indirect frequency converter. Output voltage is produced by the direct switching of output phases to input phases. The modulation strategy and control algorithm used are very important parts of the converter's controller. Common modulation strategies from the field of indirect frequency converters cannot be used in a general case because of the absence of a DC-link. Therefore, modulation strategies based on a virtual DC-link space vector modulation were developed, which works as a dependency injection. That is why different approaches can be used to control both the output voltage and the input current at the same time. In this paper phase control of the input current in combination with a sliding mode control of the output voltage is presented. This enables us to overcome the traditional limitations of the output voltage without resigning from the input current control. Since the induction machine is a system of a higher order than the action vector, an emphasis was also put on stability analysis.

Implementation of the Field Oriented Control and of the Direct Torque Control in matrix converter supplied induction motor drives is analysed in the paper. Comparison with the implementation in drives supplied by the Voltage Source Inverter is carried out. The analysis is accompanied by the results of numerical simulations and experimental implementations of these two control methods

Electric drive is an electro-mechanics energy converter. The own change of electric energy to the mechanic is done by the electric motor. For the demanded conversion of the energy needs the motor proper voltage, currents and fre-quency on its input terminals. In case of higher demands like, when the high dynamic of the motor is required, a converter is mostly connected in front of the motor. Induc-tion machine needs for its regulation frequency converter and control algorithm. In order to design control strategy for the induction mo-tor, system equations must be established at first. The target point is not given by a value of state variables, but their multiplication (mechanical torque). Moreover, depending on the coordinate system selection the destination point (or the curve) can be steadily moving. In other words, then the aim of the control is not to achieve a certain point in the state space but to produce a never ending movement that delivers the required torque as its side effect. The contribution deals with the analysis of the state space description of the induction motor based on the G-equivalent circuit of the IM. The operational limitations of the IM are mathematically derived based on the state space equations. The state space model of the IM and operational limits are then used as a starting point for the design of the IM drive control strategy based on the sliding mode control theory.

Induction machines are among the most widely used electrical-to-mechanical converters in electric drives. Their advantageous robustness and simplicity goes hand-in-hand with complicated control. A converter with a suitable control algorithm is needed in order to withdraw maximum power and dynamics from the drive. In recent times, control methods such as those based on DTC and sliding mode methods have come to the forefront, due to their robustness and relative simplicity. In the field of power converters, new converter topologies are emerging with improved efficiency that pushes the operation limits of the drive. This paper focuses on the development of a control of this kind of strategy for an induction machine fed from a matrix converter.

Induction machines belong to the most used electrical-to-mechanical converters electric drives. The advantageous robustness and simplicity goes hand-to-hand with complicated control. In order to withdraw maximal power and dynamics from the drive also the converter with proper control algorithm is needed. Recently control methods like DTC or sliding mode based ones come to the forefront due to their robustness and relative simplicity. Also on the field of power converters are emerging new topologies of converters with improved efficiency that pushes the operation limits of the drive. This paper focuses on the development of such control strategy for the induction machine fed from matrix converter.

Matrix converter belongs to the direct frequency converter category. In this contribution the name "Matrix Converter" means the symmetrical 3x3 topology made by nine bidirectional switches. Output voltage is produced by direct switching of input phases to output phases. Very important parts of the converter's controller are used modulation strategy and control algorithm. The common modulation strategies from the area of the indirect frequency converters can not be used because of the absence of the DC-link. Therefore the modulation strategies based on virtual DC-link space vector modulation were developed. It works as a dependency injection. That is why different approaches can be used to control both the output voltage and the input current at the same time. In this paper the phase control of the input current in the combination with the sliding mode control of the output voltage is presented. This enables us to overcome the traditional limitation of the output voltage without resigning from the input current control.

The structured system and software design method of the distributed control computer network of the mechatronic scientific facility for automatic high temperature material processing in the space in microgravitation environment is presented in the paper. The facility distributed computer controls special extra low speed vibrationless electric drives, multi-zone high temperature furnace heating system and several measurement devices. The computer is equipped with special technological language to be possible to specify experiment time flow. Computer network nodes have many user processes (threads) so efficient, reliable, self documented, and low overhead scheduler dispatcher is required. The table driven coroutines have been designed.

This paper deals with the development of a matrix converter. Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is being developed with sophisticated modern components (FPGA, Power PC) equipped in the control part of the converter. The converter will be used for testing new control algorithms and commutation methods

In order to stabilize the energy output and to give it some defined shape and value, the power converter must be connected to the output of the solar panel. In order to suppress or reduce negative effects the filter is connected between the converter and the network. The filter must be designed precisely, because it must have sufficient attenuation at the inverter's switching frequency and it must not bring oscillations to the whole system. This paper deals with design and simulation of such a filter type. Simulation models of the systems inverter-filter were made.

This article describes the former configuration of the control part for the experimental matrix converter and it introduces proposals for the next configuration generation as well. The former target system consists of a common personal computer, I/O card, rack, and the power circuit. Based on its overall assessment, a new configuration approach is proposed. The new system configuration promises many improvements. The communication between the control computer and the low level logic is based on the industrial PC104 bus. A new FPGA device is employed. It enables to handle all digital signals in the same time

The continuous popularity of the matrix converter control theory has been supported by steady technological improvements. It is still common to use discrete switches in an anti-serial connection, even though some integrated solutions have been presented by various vendors already. Furthermore, recently experimental all-in-one matrix converter power modules based on reverse blocking transistors were introduced. However, it does not eliminate the need of the protection circuit. This article strives to describe design procedure for one kind of the matrix converter protection circuits

The reduction of matrix converter commutation time can be obtained by means of number of steps decreasing. For this purpose the two-step voltage oriented method was developed. But some limitations of this method occurred, so the solution consisted in combining with four-step method that is naturally two times longer. The new developed two-step current oriented method can overtake the function of four-step one and fix the disadvantage of voltage oriented algorithm. Unfortunately both two-step methods are inapplicable separately.

The paper deals with the simulation of the control structure for the drive with the voltage source inverter and permanent magnet synchronous motor. The control structure is designed with the impact on the dynamic of the regulation for traction load. Realized model of the drive simulates the two level voltage fed inverter and mathematical model of the permanent magnet synchronous motor. Two control strategies of the drive are discussed in the paper.

The paper focuses on design and simulation of the low power inverter for photovoltaic application. In the paper is briefly discussed design of the DC/DC converter for the tracking MPP of the solar array and then is discussed the design of the control algorithm for the output inverter. Both possible operation modes - work in "island mode" and operation on the supply grid are considered and control algorithms for them were developed and simulated. Attention is also paid to the design of the output filter for the converter.

The effort to use renewable energy sources increase in these days. The processing of the energy obtained from the sun, wind or water gets to the forefront. The energy supplied by these sources has not constant values, but it fluctuates according to the surrounding conditions (intensity of the sun rays, water flow, etc.). Therefore these supplies are added with additional converters. The most used are AC / DC inverters or DC / DC converters. The aim of this project is to create the laboratory test bed that will pursue with energy acquisition from alternative energy sources. The attention will be paid both to the efficiency of the converters and to the control algorithm of the converter.

Příspěvek se zabývá simulací a návrhem silového obvodu jednofázového střídače pro fotovoltaickou aplikaci. Dále je v příspěvku proveden návrh a simulace řídicího algoritmu pro navržený měnič. Algoritmy jsou navrhovány pro obě možné aplikace měniče tj. pro práci na napájecí síti a pro práci v ostrovním režimu. Pro každou aplikaci je vhodný jiný řídicí algoritmus. Stručně je také rozebrána problematika návrhu výstupního filtru střídače, který je dobré připojit na výstup střídače za účelem potlačení jeho negativních vlivů.

This paper deals with the design of the control structure for the drive with the voltage source inverter and permanent magnet synchronous motor. The control structure is designed with the impact on the dynamic of the regulation. The model of the drive consists of the two level inverter model and from the mathematical model of the permanent magnet synchronous motor. Two control strategies of the drive are discussed in the paper

The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper is discussed the design of the control algorithm of the inverter for both types of inverter application - for islanding mode and for operation on the supply grid. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network

The structured system and software design method of the distributed control computer network of the mechatronic scientific facility for automatic high temperature material processing in the space in micro-gravitation environment is presented in the paper. The facility distributed computer controls special extra low speed vibrationless electric drives, multi-zone high temperature furnace heating system and several measurement devices. The computer is equipped with special language to be possible specify experiment time flow. Computer network nodes have many users processes (threads) so efficient, reliable, self documented, and low overhead scheduler-dispatcher is required. The table driven coroutines are designed.

The presented paper compares from point of view of compatibility with the supply network the above mentioned three frequency converter topologies that are being used for supplying of induction machines. The topic of the EMC of the converters becomes very important in these days, because some of the semiconductor converters can be ranked as the worse supply network polluters. These negative side effects of the converters were previously overlooked, but with the widespread of power electronics they can not be ignored more. That is why the test beds of these three frequency converter input parts were realized and experimental results obtained by the measurement were analyzed and discussed.

Presented paper deals with the design and construction of a matrix converter wtih power cca 20kW. During the design a special attention was paid to dimensions and compactness of the converter.Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is equipped with sophisticated modern components (FPGA, Power PC) in its control part.

The presented paper deals with modulation strategy of the matrix converter. Attention is paid to the indirect space vector modulation (ISVM) that is based on the virtual dc link concept. The 3D space for selection of the modulation index is being often overlooked. In this article it is discussed in detail.

The photovoltaic applications spreads in these days fast, therefore they also undergo great development. Because the amount of the energy obtained form the panel depends on the surrounding conditions, as intensity of the sun exposure or the temperature of the solar array, the converter must be connected to the panel output. In general there are two types of converters used in solar applications. The Solar system equipped with inverter can supply small loads like notebooks, mobile chargers etc. in the places where the supplying network is not present. The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper is discussed the design of the control algorithm of the inverter for both types of inverter application - for islanding mode and for operation on the supply grid. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network.

The acquisition of the electrical energy from renewable sources is very trendy nowadays. That is why the applications for renewable energy generation undergo rapid development. The greatest weakness of the renewable sources can be assumed as the instability and dependence of the delivered energy amount. In order to stabilize the energy output and to give it some defined waveform and value, the power converter must be connected to the output of the solar panel.In order to suppress or reduce these negative effects, the filter is placed between the converter and the network. The filter must be designed precisely because it must have sufficient attenuation on the inverter's switching frequency and it must not bring oscillations to the whole system. This paper deals with such a filter type design and simulation.

The paper describes the basic knowledge about the matrix converter two-step commutation method that was realized on our department. This commutation strategy was implemented in VHDL for FPGA and was simulated in Simulink/Modelsim (cosimulation). The new developed two-step commutation method is two-time faster than the formerly implemented four-step commutation method. But the cosimulation in MatLab and Modelsim has proved that it includes some limitations not respected in theoretical analysis.

This paper deals with the comparison of different frequency converter topologies from the EMC point of wiev. The negative side effects of the semicondutor converters, that were formerly overlooked, can be no longer ignored. Some topologies of semiconductor converters, that are known as worse supply network poluters, are nowadays still used as input parts of the frequency converters. To compare these side effects, test beds for different input parts used for frequency converters were made and results were analysed and compared with the special direct frequency converter topology of matrix converter.

Photovoltaic applications have been developing and spreading rapidly in recent times. This paper describes the control strategy of the Voltage Source Inverter that is the important tail end of many photovoltaic applications. In order to supply the grid with a sinusoidal line current without harmonic distortion, the inverter is connected to the supply network via a L-C-L filter. The output current is controlled by the hysteresis controller. To improve the behaviors of the L-C-L filter, active damping of the filter is being used. This paper discusses controller design and simulation results.

Photovoltaic applications have been developing and spreading rapidly in recent times. This paper describes the control strategy of the Voltage Source Inverter that is the important tail end of many photovoltaic applications. In order to supply the grid with a sinusoidal line current without harmonic distortion, the inverter is connected to the supply network via a L-C-L filter. The output current is controlled by the hysteresis controller. To improve the behaviors of the L-C-L filter, active damping of the filter is being used. This paper discusses controller design and simulation results.

The advantages of the modern regulated electric drive are not necessary to mention. Recently mostly induction maschines are used for it good behaviours. To use them optimally, the maschine has to be suplemented with frequency converter. The common indirect frequency converters have some disadvantages that can be eliminated by using matrix converters. This paper therefore deals with matrix converter fed induction machine.

This work deals with modulator of the matrix converter and his communication with superset regulator. Input voltage measurement method is presented. In the last part of the article, the testing of communication between superset regulator and modulator in FPGA technology are also presented.

Matrix converter belongs to direct frequency converter category. Output voltage is made by direct switching of input phases to output phases. This fact means that the converter does not need the DC-link capacitor which increases the costs of the converter and volume requirements of the converter. The absence of the DC-link capacitor is one of the main advantages of the matrix converter. On the other hand it means that output voltage amplitude is limited to 86.6% of the input voltage amplitude. Higher output voltage can be achieved with overmodulation which causes input current distortion. The other advantages of the converter compared to conventional indirect frequency converters are: power factor regulation; work in all four quadrants; its high dynamics; sinusoid current consumption; nearly sinusoidal output voltage waveform with low harmonic content, and high efficiency.

Matrix converter belongs to direct frequency converter category. Output voltage is made by direct switching of input phases to output phases. This fact means that the converter does not need the DC-link capacitor which increases the costs of the converter and volume requirements of the converter. The absence of the DC-link capacitor is one of the main advantages of the matrix converter. On the other hand it means that output voltage amplitude is limited to 86.6% of the input voltage amplitude. Higher output voltage can be achieved with overmodulation which causes input current distortion. The other advantages of the converter compared to conventional indirect frequency converters are: power factor regulation; work in all four quadrants; its high dynamics; sinusoid current consumption; nearly sinusoidal output voltage waveform with low harmonic content, and high efficiency.

This paper describes basic knowledge about two - step commutation method that was realized in our department. This commutation strategy was realized in VHDL for FPGA and was simulated in Simulink. But it was necessary to link Simulink with Modelsim that can simulate VHDL code. So these two sophisticated programs had to cosimulate. By virtue of this cosimulation can be uncovered, that theoretic calculations did not reflect some limitations of this two step algorithm.

This paper deals with the development of a matrix converter. Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. This is enabled by 9 bidirectional switches, which are provided by anti-serial connection of 18 IGBT transistors. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is being developed with sophisticated modern components (FPGA, Power PC) equipped in the control part of the converter. The converter will be used for testing new control algorithms and commutation methods.

This paper deals with the development of a matrix converter. Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. This is enabled by 9 bidirectional switches, which are provided by anti-serial connection of 18 IGBT transistors. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is being developed with sophisticated modern components (FPGA, Power PC) equipped in the control part of the converter. The converter will be used for testing new control algorithms and commutation methods.

The presented paper deals with comparison of measured waveforms of PWM rectifier and classical phase controlled rectifier is compared on the basis of the input current harmonic analysis.

Tato práce se zabývá modulátorem maticového měniče a jeho komunikací s nadřazeným regulátorem. Stručně je představena metoda měření vstupního napětí. V závěru práce je prezentováno provedené testování komunikace mezi nadřazeným regulátorem a modulátorem realizovaným pomocí technologie FPGA.

The modern industrial production demands continuous and lossless conversion of electrical energy parameters. This need leads to wide spread of power semiconductor converters. The rapid development in power electronics and microprocessor technology enables to apply sophisticated control methods that eliminate negative side effects of the power converters on the supply network. The phase controlled thyristor rectifiers overload the supply network with higher harmonics and reactive power consumption. Utilization of PWM control in rectifiers eliminates the problems that were caused by phase controlled rectifiers operation. That is why the PWM rectifier is being examined. In comparison with the phase controlled rectifier it can be controlled to consume nearly sinusoidal current with power factor equal to unity. Another advantage of the PWM rectifier is its capability of energy recuperation

Fázově řízené tyristorové usměrňovače zatěžují napájecí síť vyššími harmonickými a jalovým výkonem. Využití usměrňovače s PŠM řízením odstraňuje problémy, které byly způsobeny provozem fázově řízených usměrňovačů. Ve srovnání s fázově řízeným usměrňovačem může být usměrňovač s PŠM řízen tak, aby odebíral ze sítě téměř sinusový proudu s účiník blízko jedné. Další výhodou usměrňovače PŠM je jeho schopnost rekuperovat energii.

The paper describes the basic knowledge about two-step commutation method that was realized on our department. This commutation strategy was implemented in VHDL for FPGA and was simulated in Simulink/Modelsim (cosimulation). The new developed two-step method is two-time faster than the formerly implemented four-step method. But the cosimulation in MatLab and Modelsim has proved that it includes some limitations not respected in theoretical analysis.

The electromagnetic compatibility of electrical devices is going to be serious problem in these days. Many electrical devices are fed by diode or thyristor rectifiers. Such devices generate higher harmonics to the supply network and they can cause malfunction of other devices connected to the grid. Therefore, many methods for elimination of harmonics pollution are investigated. One of them is application of "grid friendly devices" as a PWM rectifier

The matrix converter is very popular topic today. Until now it has attracted mainly academic attention. It has many advantages in comparison with indirect frequency converters. As shown in this paper, the matrix converter works at high efficiency and without harmonic distortion both on the input and on the output side. The only problems are caused by the control system and by real-time control algorithms. However, new control strategies are developed, so we expect solving of these problems in recent time period.

The presented paper deals with measured waveforms of realized PWM rectifier with practically sinusoidal input current and controllable phase shift between input current first harmonic and supply voltage first harmonic. Electromagnetic compatibility of PWM rectifier and classical phase controlled rectifier is compared on the basis of the input current harmonic analysis.

Pulse width modulated rectifier is a very popular topic nowadays. The modern industrial production demands continuous and lossless conversion of electrical energy parameters. This need leads to wide spread of power semiconductor converters. The rapid development in power electronics and microprocessor technology enables to apply sophisticated control methods that eliminate negative side effects of the power converters on the supply network. The phase controlled thyristor rectifiers overload the supply network with higher harmonics and reactive power consumption. That is why the PWM rectifier is being examined. In comparison with the phase controlled rectifier it can be controlled to konsume nearly sinusoidal current with power factor equal to unity. Another advantage is its capability of energy recuperation. The paper drala with the PWM rectifier functional model realization and examination.

The PWM rectifier is in these days very popular topic. With the expansion of electronics also the conversion of electric parameters is needed. That is why the sideeffects of passive rectifiers like production of harmonics and reactive power must be respected. All this side effects falls away with the application of PWM rectifiers. This paper compares the differences between phase angle controlled rectifier and PWM rectifier.

The PWM rectifier is in these days very popular topic. With the expansion of electronics also the conversion of electric parameters is needed. That is why the sideeffects of passive rectifiers like production of harmonics and reactive power must be respected. All this side effects falls away with the application of PWM rectifiers. This paper compares the differences between phase angle controlled rectifier and PWM rectifier.

Katedra elektrických pohonů a trakce FEL ČVUT v Praze se snaží v maximální možné míře uplatnit ve výuce výsledky své vědeckovýzkumné činnosti dosažené na bázi teoretické i ve formě prakticky realizovaných vzorků. Osvědčilo se rozdělit praktickou výuku výkonové elektroniky do tří základních úrovní. V příspěvku je popsáno laboratorní cvičení spadající do druhé úrovně, kdy studenti pracují se sestaveným univerzálním obvodem měniče a soustředí se na způsoby řízení. V daném případě se studenti seznamují s funkcí a řízením usměrňovače s šířkově pulzní modulací, který umožňuje odebírat ze sítě proud prakticky sinusového průběhu a pracovat s daným fázovým posunem odebíraného proudu vůči napájecímu napětí. Porovnáním průběhů a harmonických složení veličin s klasickým usměrňovačem je demonstrováno zvýšení kompatibility měniče.

The measured results obtained on the built-up experimental test bed have proved the proper function of the designed conception of the matrix converter control system and implemented PWM strategy.

Maticové měniče mají oproti konvenčním nepřímým měničům kmitočtu řadu předností. Neobsahují akumulační členy (kondensátory, tlumivky) ve stejnosměrném meziobvodu, které zvyšují nároky na prostor, materiál a finance. Umožňují obousměrný tok energie mezi zdrojem a zátěží. Strategie šířkově pulsní modulace přitom zajišťují prakticky sinusové průběhy vstupních i výstupních veličin s možností řízení účiníku na vstupu.