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Switching sequences of multilevel inverters have to be properly chosen based on the desired control criteria such as dc-link voltage regulation, common mode voltage reduction, and other application dependent criteria. Control of a converter to satisfy a desired criterion is challenging, especially in high voltage level converters. This paper proposes a simple control method for multilevel inverters with high modularity such as flying capacitor multilevel inverters, H-bridge multilevel inverters, and modular multilevel inverters. It is shown that the method considerably simplifies generation of the switching sequences and fulfills the desired criteria with a reasonable computational cost. The proposed method is computationally efficient in the sense that its implementation for high voltage level inverters requires the same effort as required for a multilevel inverter with a low number of cells. Other prominent advantages of the proposed control method, compared to earlier methods, include its applicability for multiphase multilevel converters and converters with asymmetrical structure and/or unevenly distributed dc voltages, independence from the level number and structure of the converter, and not requiring a lookup table. These advantages make the proposed scheme well suited for high cell-number converters, mainly utilized in FACTS, HVDC, and power quality applications. Simulation and experimental results are presented which verify the performance of the proposed method. [ABSTRACT FROM AUTHOR]

The flying capacitor multilevel inverter (FCMLI) is one of the well-known structures of multilevel inverters having attracted considerable attention because of its merits. In spite of its many advantages, it has some limitations such as high volume and complicated control method because of its bulky capacitors and their voltage balancing requirement. Moreover, the high number of power semiconductors required makes this structure susceptible to failure. To increase the ratio of the number of levels to the number of components, an uneven distribution of capacitor voltages has been suggested in previous reports; however, this approach complicates the control method. Up to now, almost all presented methods suffer from high computational load and/or structure-dependent algorithm. In this paper, a simple state-based and structure-independent method is proposed for capacitor voltage regulation. The proposed method is straightforward and can perform online computation of switching sequences in a computationally efficient manner without any need for stored information or look-up tables. The method is conveniently extendible to any number of cells and levels in an FCMLI structure with arbitrary dc link voltage distribution schemes. Simulation and experimental results show the effectiveness and simplicity of this method. [ABSTRACT FROM PUBLISHER]

Appropriate structure is the first key issue that a designer of an efficient hybrid vehicle should pay attention to. This paper presents three different structures for the concept of series–parallel structure in hybrid electric vehicles (HEVs) and compares them with each other for the application of Toyota Prius 2004 as a well-known case study. The first structure consisting of one electric motor, one electric generator, and one power split device is the conventional structure as one existing in Toyota Prius 2004 and called THS-II in the literature. The second and third structures are based on two special electric machines named transmotor-based structure (TBS) and dual-mechanical-port (DMP) machine-based structure (DMPBS), respectively. The three structures are compared by considering different aspects such as weight, occupied volume, and overall efficiency. A surface-mounted fractional-slot concentrated winding DMP machine is designed, and the design is verified by applying the finite-element analysis. Simulation results have been presented to support the accomplished comparison of the structures under study. Simulation results show that all structures have approximately equal weight, volume, and efficiency, but DMPBS is a compact, efficient, and simple way to convert the existing fossil-fuel cars into an HEV. One DMP machine prototype has been implemented, and experimental results have been included. [ABSTRACT FROM PUBLISHER]

Copyright of Automatika: Journal for Control, Measurement, Electronics, Computing & Communications is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The performance of dc–dc converters plays a vital role in the exploitation of renewable energy sources such as solar and fuel cell (FC). This paper demonstrates the feasibility of using the input/output (I/O) magnetically coupled interleaved buck–boost converter, improving the conventional interleaved cascaded buck–boost converter in FC applications. While keeping the same step-up/step-down voltage transfer ratio, the proposed topology facilitates operating conditions with its nonpulsating I/O currents and high efficiency using interleaved technique and reducing switches' voltage stresses, respectively. The steady-state operation of the converter is analyzed based on the state-space-averaging method and supported with simulation results. The prototype setup of 360-W and 36-V output voltage for an FC with a brand of “FCgen 1020ACS” Ballard Power Systems, Inc. was implemented. Experimental results are presented to verify the theoretical expected merits of the converter, including high efficiency and nonpulsating I/O currents. [ABSTRACT FROM PUBLISHER]

This paper presents a direct torque control (DTC) switching scheme based on the direct matrix converter (DMC) using a 12-side polygonal space vector for variable speed control of an induction motor (IM). The conventional DTC scheme-based matrix converter (MC) is limited by 60° sectors of both flux and voltage vectors, which introduce a high torque ripple. The proposed method utilizes twelve 30° sectors of both flux and voltage vectors to increase the degrees of freedom for selection of proper vectors and reduce the torque ripple. The proposed switching scheme for the MC-based DTC of an IM drive select the appropriate switching vectors for control of torque with small variations of the stator flux within the hysteresis band. This improves the degrees of freedom in selecting the vector algorithm and the torque ripple as well. Furthermore, during the large torque demand, the probabilities of transgressing reference vector limits, which are enclosed by 12-side polygonal space vector, are reduced. Extensive simulation and experimental results are presented to verify the effectiveness of the 12-sector space vector switching scheme for the DTC of an IM fed by the DMC. [ABSTRACT FROM AUTHOR]

There are growing interests in electric and hybrid electric vehicles (HEVs) because of environmental concerns. Recent efforts are directed toward developing an improved propulsion system for electric and HEVs applications. In a conventional series-parallel HEV, a planetary gear is used to integrate the power of internal combustion engine and two electric machines into the drive train so that the engine can always operate with the highest efficiency while the vehicle runs at any desired speed and torque. However, two electric machines and associated power inverters along with a planetary gear make the HEV drive train much more complicated and bulky in size. Dual-mechanical-port electrical machine (DMPM) is a new breed of energy conversion device with more compact and integrated structure that can potentially realize an efficient electrical variable transmission for HEV applications. This machine can replace the planetary gear and two electric machines of conventional structure in order to make their structures much simpler. Applying a proper power management and control strategy to have a good driving performance for a series-parallel HEV based on DMPM are the main contributions of this paper. Because Toyota Prius II (Toyota Motor Sales, U.S.A., Inc., Torrance, CA, USA) is a well-known series-parallel HEV, the parameters of this vehicle are chosen as a practical example in simulation results. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Copyright of Automatika: Journal for Control, Measurement, Electronics, Computing & Communications is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Among the alternative methods for energy storage , using the potential energy of water stored in different heights has been considered by human for ages. Storage pumping plants have been invented for this purpose and are considered as one of the most reliable and effective methods of storing the electrical energy. Factors such as having appropriate static and dynamic stability, high efficiency, suitable steady state and transient performance, the least cost of manufacturing, utilities and etc. can play a major role in choosing the type of machines for energy-making. Therefore, advantages and capabilities of variable speed storage-pumping plants, compared with conventional synchronous ones, have drawn into consideration in this paper. Different viewpoints such as structure and steady state behavior are focused for comparing the application of Doubly Fed Induction Generators (DFIG) and synchronous ones in storage hydro plants. Dynamic stimulations are also used to evaluate the performance of variable-speed versus synchronous fixed-speed generation units. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes an average model of indirect matrix converter (IMC) with an output LC filter in stationary and rotating reference frames. The developed model is non-linear and should be linearized in order to design linear controllers. Transient performance of the IMC is compared with that of conventional inverter in classic AC/DC/AC system. In order to make the IMC applicable for power conditioner applications a synchronous controller is designed. A power conditioner acts in one or more ways to deliver a voltage of the proper level and characteristics to enable load equipment to function properly. In order to afford the power conditioner requirements the controller has two segments. One segment controls the IMC with balanced input supply voltage and the other controls the system with unbalanced input supply voltage. The system can provide balanced output voltages with slight distortion of line side currents. Theory analyses, the model validation and simulation results are presented to verify the effectiveness of this control method. [Copyright &y& Elsevier]

In this paper the role of the voltage vectors of a two-level converter on variations of active and reactive power of a Doubly Fed Induction Generator (DFIG) is studied more deeply. Previous approaches only have a qualitative look toward this issue that consequently, leads to extraction of an optimal switching table. With expanding accurate equations describing the variation of active and reactive power, this paper is going to inspect the role of the voltage vectors in active and reactive power control of a DFIG exactly, and to illuminate thoroughly the impression of terms like rotor velocity and load angle variation, neglected in the previous works. Expanding these equations provides the ability of scrutinizing the effect of the converter voltage vectors on active and reactive power of the machine at any operating point. This leads to achievement of a more accurate and optimal switching table. The distinction of this method accounts it as a good candidate for online methods to predict the effect of each voltage vector on active and reactive power variation. [ABSTRACT FROM AUTHOR]

This paper describes an average model of Indirect Matrix Converter (IMC) with an output LC filter in stationary and rotating reference frames. The developed model is non-linear and should be linearized in order to design linear controllers. In order to make the IMC applicable for power conditioner applications a synchronous controller based on pole placement technique is designed. A power conditioner acts in one or more ways to deliver a voltage of the proper level and characteristics to enable load equipment to function properly. in order to afford the power conditioner requirements the controller has two segments. One segment controls the IMC with balanced input supply voltage and the other controls the system with unbalanced input supply voltage. The system can provide balanced output voltages with slight distortion of line side currents. Theory analyses, the model validation and simulation results are presented to verify the effectiveness of this control method. [ABSTRACT FROM AUTHOR]

Interior permanent magnet synchronous motors (IPMSMs) are attractive in hybrid electric vehicles (HEVs) because of the high efficiency and ability to operate in the field- weakening mode for extended speed range. In HE V application, under a driving schedule, the traction motor has to operate in both the constant-torque and constant-power regions due to the wide speed range. This paper aims to improve the IPMSM control technique in both aforementioned regions and maintain the ability to change between them quickly, by considering all factors affecting it such as the dc-link voltage, battery pack and electric motor maximum permissible currents, motor speed, and torque request. The maximum torque per ampere (MTPA) and field-weakening control techniques are chosen in the constant-torque and constant-power regions respectively. Thereafter, the proposed control technique is used to examine the IPMSM performances under city as well as highway driving conditions. [ABSTRACT FROM AUTHOR]