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Appropriate position estimation of electric actuator is one of the most important stages in the control and automation processes. Considering various applications including robotics and automotive systems, Brushless DC (BLDC) motors sensor-less positioning is substantial in two major aspects. Electric commutation on the electric side should be performed precisely as well as motion control on the mechanical side. The mathematical models which befit precise applications are inherently nonlinear and require specific control techniques to deal with. Nonlinear Kalman filtering methods are considered as suitable solutions to estimation problems where uncertainty and noise exist. Three major and basic algorithms are Extended (EKF), Unscented (UKF) and Cubature Kalman filtering (CKF). In this paper, the application of these methods in estimation of rotor angular position with emphasis on low speed state is presented. Performance measures are compared using experimental setup. A typical 3-phase low voltage BLDC motor is implemented in the setup so that system noise could deteriorate quality of Back-EMF signal in low speed mode. It is shown that UKF and CKF techniques yield better results and performance in comparison to EKF according to measures. Estimated model states diagrams indicate the superior performance of Unscented and Cubature types regarding both accuracy and convergence. [ABSTRACT FROM AUTHOR]

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]

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]

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]

Dynamic behavior of DC–DC converters plays a crucial role in stability of renewable energy exploitation systems. This paper presents small signal modeling of an input/output magnetically coupled interleaved buck–boost converter for fuel-cell applications to help the designers with the better understanding of converter dynamics. Aiming to have a continuous converter transfer function for a smooth transition between the operation modes and an improved inner dynamics, a damping network and an input/output coupling have been added to the interleaved structure of well-known cascaded buck–boost converter. Having the same step-up/step-down voltage transfer ratio, smooth transition and improved inner dynamics make this converter quite suitable for renewable energy applications. The paper presents a small signal ac equivalent circuit model of the proposed converter based on state space averaging (SSA) method. Simulation results show remarkable improvements in converter dynamic behavior in both time and frequency domains. Prototype setup of 360 W and 36 V output voltage for a fuel cell with a brand of “FCgen 1020ACS” Ballard Power Systems, Inc. was implemented. Experimental results are presented to verify the theoretical model and its expected merits. [ABSTRACT FROM AUTHOR]

Efficiency and dynamics of DC-DC converters play a major role in proficiency of renewable energy exploitation. This paper presents a novel DC-DC interleaved buck-boost converter for fuel-cell applications. While keeping the same step-up/step-down voltage transfer ratio, the proposed converter exhibits non-pulsating I/O currents using interleave technique. A damping network is also added to improve the inner dynamics of converter. Besides the steady state operation based on state space averaging (SSA) method, design considerations of converter are thoroughly elaborated. MATLAB/SIMULINK environment is used for simulating the steady state operation of proposed converter, and the experimental results are presented, to verify the theoretical expected merits of the converter including high efficiency, non-pulsating I/O currents and low voltage oscillation. Prototype setup of 360 W and 36 V output voltage for a fuel cell with a brand of "FCgen 1020ACS" Ballard Power Systems, Inc was implemented. Experimental results including efficiency and time domain responses in the steady state show impressive benefits of the proposed converter. [ABSTRACT FROM AUTHOR]

Abstract: Having a voltage transfer ratio lower than unity with a 0.866 upper limit, even lower than 0.866 in the course of experiments because of parasitic components of real power circuits, is one of the shortcomings of matrix converters. This deficiency is one of the greatest impediments to industry adaptation of matrix converters. To surmount this barrier this paper proposes a novel modification in circuit topology of indirect matrix converters (IMC) achieving voltage boosting and unity voltage transfer ratio. Besides preserving the inherent advantages of the conventional matrix converters, such as controllability of input power factor, sinusoidal input/output currents and the ability of bidirectional power flow, the remarkable feature of this solution is that, unlike the other research in this field no special control strategy or additional reactive elements at the DC-link is used and the integrity of the converter has been kept as much as possible. Furthermore a new efficient switching strategy is proposed for the new converter. Simulation results are shown to support the given theoretical analyses and experimental results obtained from a 5kW converter verify the full functionality of the proposed topology. [Copyright &y& Elsevier]

Abstract: Three leg inverters for photovoltaic systems have a lot of disadvantages, especially when the load is unbalanced. These disadvantages are for example, small utilization of the DC link voltage, the dependency of the modulation factor of the load current and the superposition of a DC component with the output AC voltage. A solution for these problems is the four-leg inverter. Consequently, generation of balanced voltage with sinusoidal waveform is necessary for these inverters. The power stage model of the 4-leg inverter in rotating coordinates dqo is highly coupled. Consequently, controller design procedure is very difficult and complex. On the other hand, adaptive control for 4-leg inverters has not yet been discussed in the literature. This paper proposes the state feedback approach to decouple the system and convert it to a second-order system which has two poles equal to zero. Then, it suggests a compensator to cancel poles of the closed-loop system and to convert the final system to a desired second-order system. Thanks to use of this strategy the transient performance of the system, such as overshoot and speed of response, becomes greatly adjustable. In addition, an STR (Self-Tuner Regulator) is introduced to tune the state feedback matrix and to guarantee the adaptive performance of the system. Simulation results validate that, by using proposed control strategy, the 4-leg inverter generates balanced voltage, with perfect sinusoidal waveform, in spite of the presence RL time-variant loads. [Copyright &y& Elsevier]

Abstract: Three-leg inverters for photovoltaic systems have many disadvantages, especially when the load is unbalanced. These disadvantages are, for example, small utilization of the DC link voltage, the dependency of the modulation factor of the load current and the superposition of a DC component with the output AC voltage. A solution for these problems is the 4-leg inverter. Most papers dealing with 4-leg inverters suggest classic controllers, such as PI controller, for the system. However, the transient performance of the closed-loop system does not become acceptable. On the other hand, adaptive control of 4-leg inverters has not yet been discussed in the literature. This paper proposes pole-placement control strategy, via state feedback, for 4-leg voltage-source inverters to adjust the transient performance of the closed-loop system. In addition, a STR (self-tuner regulator) is introduced to guarantee the adaptive performance of the controller in the presence of time-variant RL loads. Simulation results validate the theoretical results and proposed control strategy. [Copyright &y& Elsevier]

Abstract: Three leg inverters for photovoltaic systems have a lot of disadvantages, especially when the load is unbalanced. These disadvantages are for example, small utilization of the DC link voltage, the dependency of the modulation factor of the load current and the superposition of a DC component with the output AC voltage. A solution for these problems is the 4-leg inverter. Most papers dealing with 4-leg inverters ignore the effect of digital delays in control loop and suggest classic controllers, such as PI controller. However, the transient performance of the system does not become adjustable by applying classic control techniques. Additionally, adaptive control techniques have not yet been discussed for 4-leg inverters. This paper proposes the pole-placement control strategy via state feedback with integral state, which is a modern control technique, to control the system. Consequently, resulted system becomes highly robust. In addition, it suggests a Self-Tuner Regulator to guarantee the adaptive performance of the final system. Moreover, it proposes a novel model, considering digital delays, for 4-leg inverters. Simulation results show that transient performance of the system becomes accurately adjustable and the 4-leg inverter generates balanced voltage, with sinusoidal waveform, in spite of the presence of RL time variant loads. [ABSTRACT FROM AUTHOR]

Abstract: Three leg inverters for photovoltaic systems have a lot of disadvantages, especially when the load is unbalanced. These disadvantages are for example, small utilization of the DC link voltage, the dependency of the modulation factor of the load current and the superposition of a DC component with the output AC voltage. A solution for these problems is the four-leg inverter. Most papers dealing with 4-leg inverters ignore the effect of digital delays in control loop and suggest classic controllers, such as PI controller. However, the transient performance of the closed-loop system does not become, accurately, adjustable and acceptable, in most cases. This paper proposes a novel model, considering digital delays, for 4-leg inverters. Then, it applies pole-placement control strategy, via state feedback, to adjust the transient performance of the closed-loop system to a desired second-order system. Simulation results validate theoretical results and proposed control strategy. [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]

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]

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]