The aim of the paper is to present a concept of implementation of a space vector modulation (SVM) algorithm, which is used to create alternating current waveforms of changing amplitude and frequency in power inverters. The main goal of the method is to decrease the number of state changes in power transistors. It is realized by utilizing a prediction algorithm and sequences of transistors, which are not common in use. The method requires measurement of inverter output current flow. The prediction algorithm analyzes possible sequences of transistors’ states and choose those which offers smaller switch count. A decrease of about 20% was obtained for the cases tested. This paper presents simulation result for selected driving scenario. The described method decreases the number of state changes in power transistors and therefore it is a potentially good method to considerably decrease energy losses of multilevel inverter-powered drive.
This paper presents the research results of a multilevel switched capacitor DC-DC converter (MLSCC). The converter, for power electronic applications, can operate in ZCS mode by utilizing resonant circuits for recharging the switched capacitors. The main focus of this article is an in-depth original analysis of the waveforms and the converter voltage ratio. The concept of the converter is verified by simulation results of the circuit in MATLAB/Simulink Sim Power Systems. The formulas given in the mathematical analysis are evaluated for example parameters of the components with the use of numerical approach in MATLAB software. Plot sets are presented in order to judge the influence of the parameters on converter performance. All non-expected relations are explained based on mathematical analysis. The possibilities of the design optimization are identified and presented based on the anticipated results. The present analysis is important for the converter design process and can be used for numerical multi-object optimization to further improve the converter design.
The flying-capacitor (FC) topology is one of the more well-established ideas of multilevel conversion, typically applied as an inverter. One of the biggest advantages of the FC converter is the ability to naturally balance capacitor voltage. When natural balancing occurs neither measurements, nor additional control is needed to maintain required capacitors voltage sharing. However, in order to achieve natural voltage balancing suitable conditions must be achieved such as the topology, number of levels, modulation strategy as well as impedance of the output circuitry. Nevertheless this method is effectively applied in various classes of the converter such as inverters, multicell DC-DC, switch-mode DC-DC, AC-AC, as well as rectifiers. The next important issue related to the natural balancing process is its dynamics. Furthermore, in order to reinforce the balancing mechanism an auxiliary resonant balancing circuit is utilized in the converter which can also be critical in the AC-AC converters or switch mode DC-DC converters. This paper also presents an issue of choosing modulation strategy for the FC converter due to the fact that the natural balancing process is well-established for phase shifted PWM whilst other types of modulation can be more favorable for the power quality.
S. Piriienko, A. Balakhontsev, A. Beshta, A. Albu and S. Khudoliy
The paper deals with improvement of efficiency of energy storage devices for electric vehicles. The benefits and features of the hybrid energy storage system based on the batteries and ultracapacitors are described. The possible topologies and common schematics of bi-directional DC/DC converters for energy storage are analyzed in terms of efficiency, reliability and battery maintenance. An algorithm for optimization of its parameters is developed, analyzed, shown and explained in detail. The surfaces, which show the dependence between required battery and ultracapacitors’ capacities, energy storage cost and battery discharge ratio are obtained and analyzed. Conclusions are drawn concerning optimization strategy and results of optimization with possible further improvements.
Roberto Quintal-Palomo, Mateusz Dybkowski and Maciej Gwoździewicz
A review of the literature gives several guidelines for the design of a Permanent Magnet Synchronous Generator (PMSG) for Small Wind Turbines (SWT) applications. This paper presents Finite Element Analysis (FEA) of a Surface Mounted PMSG. Several optimization tests are run in order to yield the lowest Total Harmonic Distortion (THD) and cogging torque with the highest induced voltage. The results of the optimization tests are then utilized to design an initial “optimized” circumferential Internal PMSG. This optimized design is then compared to a non-optimized design, as well as the results of the Surface Mounted PMSG.
The paper presents a sensorless control of permanent magnet synchronous generator (PMSG) in a variable-speed wind energy conversion system. The system of wind turbine consists of PMSG and back-to-back power converter. The back-to-back converter system is composed of machine side converter (MSC) and grid side converter (GSC). In the control of MSC and GSC the methods of vector control have been applied. For operation of MSC the method of Rotor Field Oriented Control (RFOC) with MPPT algorithm has been used. For estimation of angular rotor position and angular speed the flux linkage estimator with synchronous frame phase locked loop (SF-PLL) has been used. In the control of GSC the method of Voltage Oriented Control (VOC) has been considered. Simulation studies have been carried out in order to evaluate the system of sensorless strategy. The results of simulation studies demonstrate the high efficiency and high accuracy of the sensorless control system considered.
The article deals with single-phase line start permanent magnet synchronous motor with skewed stator. Constructions of two physical motor models are presented. Results of the motors running properties are analysed.
Power delivery infrastructures are overstrained and suffer from overaged conditions, not only in the developed, but also in the more industrialized countries. The aim of the smart grid is to provide a more reliable and efficient electric power grid. Condition assessment is an essential and effective part of the reliability for electric grid components; also, it reflects the physical state of the electricity asset in a generation, transmission, distribution, and consumers sides. In this paper, condition assessment of electric grid assets will be discussed and illustrated within the context of smart grid principle. In addition, the proposed condition assessment architecture and the objective of condition assessment for smart grid equipment will be explored and analyzed. Moreover, the potential benefits of such smart system as compared to the traditional power system will be presented. This paper aims to add significant contribution to a smart grid theory.
This paper deals with the stability analysis of MRAS current speed estimator in a motoring and regenerating mode. The unstable operating points of the estimator, mainly in a regenerating mode are widely discussed. The expanded version of the estimator MRASCC is proposed to provide its stability in the whole operating range. The new correction coefficients for two analyzed stabilization methods are proposed. Finally, simulation results confirming the theoretical analysis are presented
The article is a summary of previous work on the possibility of using Petri layers in adaptive neuro-fuzzy controllers. In the first part of the paper the controller and two types of Petri layer have been presented, competitive layer which resets certain signals and transition layer which causes omission of signals. Layer properties were described and comparison has been made. In the second part of the paper, the results of a simulation showing the advantages and disadvantages of proposed solutions have been presented. Both quality of reference signal tracking and energetic cost of control process have been calculated. In the last part, analysis and comments on the results were made. Main conclusions are that transition Petri layer can significantly reduce growth of numerical cost of the algorithm despite the increase of fuzzy rules count. Also both competitive Petri layer and transition Petri layer by changing some inner signals can affect output value of the fuzzy system and thus the control quality indicators change. Most positive solutions have been pointed out.