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Home>Products>Journal and Reviews>I.R.E.E.>Latest issue International Review of Electrical Engineering Vol. 5 N. 2-- Part A International Review of Electrical Engineering Vol. 5 N. 2-- Part B
International Review of Electrical Engineering - April 2010 - Papers Part A
International Review of Electrical Engineering - Papers- Part A
Vol. 5. n. 2, pp. 347-355
Abstract - This paper presents the system analysis and circuit characteristics of an interleaved soft switching dc-dc converter. One auxiliary switch and one fast recovery diode are connected between the half-bridge leg and the middle point of split capacitors to generate three different voltage levels on the primary side of transformer. The zero voltage switching (ZVS) is achieved at the transition interval between power switches. The current doubler rectifier is adopted in the secondary side of transformer to reduce the current stress on the transformer secondary winding and achieve the ripple current cancellation on the output capacitor such that the sizes of the output chokes and capacitor are reduced. The interleaved PWM scheme is used to achieve load current sharing, reduce the ripple current on the input side and regulate the output voltage. Finally, experimental results based on a 500W (12V/42A) prototype are provided to verify the theoretical analysis and effectiveness of the proposed converter. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Zero Voltage Switching, Power Conversion, Converters.
Vol. 5. n. 2, pp. 356-363
Abstract - One of the most important problems in power electronic, especially inverters, is its switching. The amplitude of the harmonics can be reduced by using of multilevel inverters. So it leads to decrease of output current total harmonic distortion (THD). In the multilevel current source (MLCSI) the entire harmonics cannot be removed and some of them can be appeared in the output current. This paper presents a novel method in which combination of chops and short circuit pulses are positioned in such a way that lower order harmonics are eliminated selectively besides current magnitude modulation with minimum switching frequency. Generalized equations which show the relationship of various PWM-SHEM parameters to the position of short circuit pulses and the number of chops per 360o are provided and discussed in details. To verify proposed method, a sample multilevel current source inverter has been designed and simulated in PSPICE. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Pulse Width Modulation, Multi Level Current Source Inverter, Selective Harmonic Elimination, Modulation Index and Current Control.
Vol. 5. n. 2, pp. 364-370
Abstract - This paper presents a single-stage ac-dc converter with high power factor to reduce line current harmonics and compensate input reactive power. An integrated buck-zeta converter is adopted to reduce the voltage stress on medium dc bus. Thus low voltage stress of power switch can be used in the converter. Since the buck converter is operated in the discontinuous conduction mode (DCM), the ac line current is automatically following the utility voltage and line current is a sinusoidal waveform and in phase with ac mains. The zeta converter is used to regulate the output voltage and reset the transformer magnetic flux. The system analysis, operation principle and design consideration of the proposed converter are presented. Experimental results, taken from a laboratory 200W prototype, are presented to demonstrate the converter performance. Based on the experimental results, the proposed converter reached a power factor of 0.98, a total harmonic distortion of 8% and an efficiency of 88%. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Power Factor Correction, Buck, Zeta.
Vol. 5. n. 2, pp. 371-379
Abstract - Diode and thyristor rectifiers are widely used in electric motor drive systems. These nonlinear loads produce current harmonics that reduce power quality by distorting the utility voltages. One possibility to improve the power quality is to compensate the harmonics with an active power filter. The active filtering functionality can also be integrated to active rectifying mode. In this study, the Vienna rectifier operating in combined rectifying and active filtering mode is studied. The paper presents an adaptive space vector modulation method that improves the harmonic compensation capabilities of the space vector controlled Vienna rectifier. The theoretical analysis is verified with simulations and measurements from laboratory prototype feeding a 5-kW load. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Active Filter Function, Reference Shaping, Space Vector Modulation, Three-Level Rectifier, Unidirectional Rectifier.
Vol. 5. n. 2, pp. 380-389
Abstract - An interleaved forward converter with zero voltage switching (ZVS) turn-on is provided in this paper. Two identical converter modules are connected in series at the input and output sides of the proposed converter with interleaved pulse-width modulation (PWM) scheme to reduce the ripple current on the output capacitor and to reduce the voltage stresses on power switches. In each converter module, two active-clamping forward converters are used to share the current stress on the switch and reduce the ripple current at the input side. Instead of four switches in the conventional interleaved ZVS converter, only two switches are used in each converter module to achieve the interleaved PWM operation and realize the ZVS turn-on for all switches. Each switch is operated as the main switch for one forward converter and also as the auxiliary switch for the other forward converter. Thus, the circuit cost and control complexity in each module are reduced. The resonant inductance and the output capacitance of switch are resonance in the transition interval. Thus, the switches can be turned on with ZVS feature at this instant. These features make the proposed converter suitable for the dc converter with high input voltage applications. Finally, experiments based on a 600W (24V/25A) prototype are provided to verify the theoretical analysis and the effectiveness of the proposed converter. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Zero Voltage Switching, Forward, Interleaved PWM.
Vol. 5. n. 2, pp. 390-396
Abstract - This paper presents an improved parallel resonant push-pull inverter for induction heating applications by using integral cycle control. In this method the switching frequency is defined by Phase Locked Loop (PLL) circuits. The aim of this paper is to design a small and high efficiency package for an induction heating. The proposed topology has been analyzed in steady state and transient conditions. One of the advantages of this modification is the low harmonic in ac-line current; the THD is less than %2. The validity of this method is verified through computer simulations and hardware experiment at the operating frequency of 55 kHz to 60 kHz. The simulation results and experimental results are in good agreement. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction Heating (IH), Current Source Inverter, Soft Switching, PLL, Integral Cycle, Total Harmonic Distortion (THD).
Vol. 5. n. 2, pp. 397-408
Abstract - In this paper, two wind turbines equipped with a permanent magnet synchronous generator (PMSG) and respectively with a two-level or a multilevel converter are simulated in order to access the malfunction transient performance. Three different drive train mass models, respectively, one, two and three mass models, are considered in order to model the bending flexibility of the blades. Moreover, a fractional-order control strategy is studied comparatively to a classical integer-order control strategy. Computer simulations are carried out, and conclusions about the total harmonic distortion (THD) of the electric current injected into the electric grid are in favor of the fractional-order control strategy. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fractional-Order Controller, Pitch Control Malfunction, Wind Energy, Power Converters, Power Quality.
by H. Afshari, M. Nazari, M. Davari, G. B. Gharehpetian Vol. 5. n. 2, pp. 409-415
Abstract - Dynamic Voltage Restorer (DVR) is a cost effective approach for the protection of sensitive consumers from voltage sags. Voltage sags always happen in a few times and are related with short circuit events and starting motors which needs high lagging current. Implementations of the DVR at a Medium Voltage (MV) level give an opportunity, to protect large sensitive loads from voltage sags. The control of DVR with Sliding Mode Control (SMC) method makes it multi-purpose for the compensation of the voltage sag, swell, flicker and harmonics. In this paper, the minimum energy injection concept has been used for restoration during DVR compensation. Analysis and simulation using MATLAB has been shown that the voltage is perfectly controlled across the critical load. The simulation results have been compared with the experimental results, which verify the capabilities of the proposed control method. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Dynamic Voltage Restorer (DVR), Large Sensitive Loads, Sliding Mode Control (SMC), Voltage Sag.
by Tsao-Tsung Ma Vol. 5. n. 2, pp. 416-425
Abstract - This paper describes a novel design of a high-performance, grid-connected inverter. The proposed inverter is particularly suitable for small PV systems that are required to feed power to the grid with a number of critical features, i.e. unity power factor, high step-up and high system efficiency. The topology of the proposed inverter is formed by a modified flyback DC/DC converter with a controlled output current source and a full-bridge converter operating with line-frequency switching techniques. With this special circuit arrangement, the proposed inverter is able to recycle the leakage inductance energy with a clamped capacitor and cascade the secondary winding inductor via the converter output path to achieve high efficiency and high step-up characteristics. For the convenience of conducting experiments in the laboratory and eliminating the possible effects of the weather conditions, a PV module emulator realized with a half bridge converter is also developed to replace the real PV module in the hardware tests carried out in this paper. An 80W prototype PV inverter system is built based on the proposed design method. The feasibility and effectiveness of the proposed inverter system are confirmed with some PSIM simulations and experimental results. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: PV Inverter, Flyback Converter, PV Module Emulator, Dispersed PV Energy Unit.
Abstract - This paper presents a robust control design procedure for induction motor drives in case of modeling errors and unknown load torque. The control law is based on the combination of nonlinear PI controllers and a backstepping methodology. More precisely, the controllers are determined by imposing flux-speed tracking in two steps and by using appropriate PI gains that are nonlinear functions of the system state. A comparative study between the proposed PI/Backstepping approach and the feedback linearizing control is made by realistic simulations including load torque changes, parameter variations and measurement noises. Flux-speed tracking results show the proposed method effectiveness in presence of strong disturbances. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Nonlinear PI Control, Backstepping, Induction Motor, Robustness, Flux-Speed Tracking, Feedback Linearizing Control.
Vol. 5. n. 2, pp. 433-436
Abstract - Control circuits allow the performance increase of the power electronics converters through the implementation of advance control techniques. This paper describes the implementation of the DPWM-S4 technique on a microcontroller and compares the practical analysis results and the simulation results. The greatest advantage in using this command technique is the reduction by 1/3 of the power dissipated by the power transistors within a three-phase inverter. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Motor Control, Power Electronics, Microcontroller, Algorithm.
Vol. 5. n. 2, pp. 437-446
Abstract - Synchronous reluctance machine with simple salient rotor are known to have poor power factor because they have a low effective reactance ratio. This paper used a 3-phase auxiliary winding and balanced capacitance compensation to influence the effective reactance ratio of a synchronous reluctance machine with simple salient rotor structure, such that its power factor and torque/ampere performance is improved. A mathematical model and dq equivalent circuit suitable for dynamic and steady state analysis was developed and used to study the synchronous operation of this machine. Analytical as well as experimental results for a 4-pole, 36 slots simple salient rotor reluctance machine showed that the effective reactance ratio increased with the capacitance size, and the machine operated at a maximum power factor of 0.969 without altering the geometry of the rotor. The torque per ampere of the machine also improved with the size of capacitor attached to the auxiliary winding. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Balanced Auxiliary Winding, Capacitor Compensation, Dual Winding, Synchronous Reluctance Machine, AC Machines.
Vol. 5. n. 2, pp. 447-453
Abstract - The high-frequency stray load losses (LLr), at rated current, are a result of increase motor current from no-load value (I0) to rated value I=IN. They can be estimating by high frequency no-load losses due to MMF higher harmonics (PHF,f0). The basic idea is to divide the stray no-load losses in two components: first component, high frequency stray no-load losses due to the slot permeance harmonics (PHF,0), is proportionate to the squared motor no-load voltage value; and component of high frequency no-load losses due to MMF higher harmonics (PHF,f0) is proportionate to the squared motor no-load current value. Also, it is shown that the high frequency no-load losses due to MMF higher harmonics (PHF,f0n) can be determined only by no-load test with slip measurement by stroboscope method. Synchronous speed measurement test can be omitted. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: MMF Higher Harmonics, Slot Permeance Harmonics, No-Load Test, Stray Load Losses, Stray No-Load Losses, Synchronous Speed Measurement Test.
by Ghazanfar Shahgholian, Jawad Faiz, Navid Sedri, Pegah Shafaghi, Mehdi Mahdavian Vol. 5. n. 2, pp. 454-461
Abstract - – In this paper the design and manufacture of a drive for Two-phase induction motor is represented by dig¬ital programming techniques for achieving the desired motivating switching pulses. The motor considered motor for practical exper¬im¬e¬n¬ts is a special motor that is named ac-c¬um¬ulator. This motor has a low power and controllable speed. The main application of this motor is in weaver industries and it is designed for working in hot, humid and dusty and dusty e-n¬¬v¬¬¬i¬ronments and also its drive should be capable for continuously work in such environments. So effort has been done that the components in the act¬ual and simul¬a¬t¬ed models be exactly the same. In this way the obtained outputs will be com¬p¬a¬r¬ed and the better results will be achieved. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Two-Phase Induction Motor, Design, High Speed.
Vol. 5. n. 2, pp. 462-472
Abstract - This paper investigates the feasibility and performance of applying fuzzy based iterative learning control (ILC) algorithms in advanced control applications of induction motors. Based on different motor operating conditions, the proposed new control scheme using the proportional-integral controller plus iterative learning control algorithms is designed with the aid of on-line parameters tuning on a fuzzy controller and the particle swarm optimization (PSO) technique. The mathematical formulation of an induction motor and the design theory of the proposed adaptive ILC control scheme are firstly described. Then, comprehensive computer simulations and practical hardware tests are performed to demonstrate the unique features of the proposed control scheme. In this paper, the feasibility and performance of the proposed intelligent control schemes are compared with the conventional PI controllers in terms of speed tracking errors and robustness when a special periodic disturbance is encountered. In hardware implementations, several complex computational and signal processing tasks are accomplished using the TI DSP2812 chip. The simulation tasks and hardware implementation of controllers with various test examples are carried out via a personal computer, DSP and the VisSim software environment. Typical simulation and experimental results are presented to show the effectiveness of the proposed control scheme. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction Motor, Iterative Learning Control, Fuzzy Algorithm.
Vol. 5. n. 2, pp. 473-480
Abstract - The paper presents and compares two control structures for the excitation control of a synchronous generator. The first structure includes a neural network-based voltage controller. The proposed feedforward neural network integrates a voltage controller and a power system stabilizer. The modified error function used for the on-line training of neural networks by employing the backpropagation algorithm uses voltage reference and terminal voltage. The second structure includes a fuzzy logic controller with two control loops: a voltage control loop and a stabilization control loop with the function of a power system stabilizer. The proposed control algorithms as well as the conventional control structure are implemented in a digital control system and tested in a laboratory environment on a synchronous generator connected over a transmission line to an AC network. The experimental results described in this paper justify the use of advanced control structures based on neural networks and fuzzy logic in the excitation control system of a synchronous generator. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Synchronous Generator, Dynamic Stability, Stability Limit.
Vol. 5. n. 2, pp. 481-490
Abstract - This
paper deals with the design and experimental realization of an adaptive
speed fuzzy controller used with conventional PI controller. The
developed controller is designed in accordance with IP and
Ziegler-Nichols tuning criteria, using Dspace1104 and Matlab/simulink
environment. The most important is that this method doesn’t replace the
conventional controller but improves the system dynamic performances
which represent an economic solution for existing applications. Only
rules based on human’s heuristic in manipulating and implementing are
added. The parameters adaptation operation is then easy to be applied. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction Motor, Vector Control, Fuzzy Logic, Dspace.
Vol. 5. n. 2, pp. 491-497
Abstract - Open slots in concentrated wound permanent magnet motors are a desirable property from the manufacturing point of view. In such machines it is possible to use pre-fabricated full-processed coils giving an advantage in terms of manufacturing costs of the stator winding. In this paper the machine type with the rotor surface mounted magnets is studied in order to compare how the motor losses and torque capabilities behave with either open or semi-closed stator slots. It was noticed that using semi-closed slots the I2R losses and the eddy current losses in the magnets were lower if compared with similar motors having open slots. However, the semi-closed slot structures had slightly higher iron losses than the corresponding open slot structures. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: AC Motors, Concentrated Windings, Low Speed, Permanent Magnet Motors.
Vol. 5. n. 2, pp. 498-507
Abstract - This paper presents a detailed numerical analysis of the complex bifurcation sets of a typical three-phase induction motor (IM). In fact, the dynamical properties of this electrical machine exhibit a rich behavior due to significant non-linearities and many motor parameters can vary significantly over the operating temperature range and saturation level. Moreover, the faults that occur in this kind of motor as well as the inter-turn short circuit fault in the stator windings can cause an abruptly change of parameters values. Therefore, all parameters are assumed to vary as a function of these conditions. So it is necessary to examine the effects of the parameters variation on the dynamic behavior of the motor. The study of the motor dynamics steady state is expected under both zero-load torque and nominal load torque motor tests. The main focus of this work is to present a numerically based study of the stability proprieties and the bifurcation phenomena concerning these limit points. Thus, structural stability is analyzed through the fluctuation of motor parameters such as rotor-stator resistors, inductors and mutual inductance. Therefore, it is observed that Saddle-node, Hopf and Generalized-Hopf bifurcations are the singularity subsets of the overall bifurcation phenomena that this machine may exhibit under parameters vary. Moreover, varieties of phenomena, such as jump and hysteresis, which may lead in these bifurcations, are carried out. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction Motor, Bifurcation, Saddle-Node, Hopf, Structural Stability.
Vol. 5. n. 2, pp. 508-513
Abstract - Electrical machines can be well analyzed by using a coupled finite element (FE) –boundary element (BE) methods. The nonlinear parts are best discretized by finite element method, whereas the space between moving bodies is discretized by the boundary element method. This discretization scheme is well suited for problems including moving parts. The description of a comprehensive design procedure for a switched reluctance motor (SRM) is being presented. The procedure combines both an analytical calculation of the main dimensions of the SRM and a coupled FE-BE method to predict the performance of the candidate design. A design example of 5hp SRM has been carried out to illustrate the merit and efficiency of the proposed design procedure. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Switched Reluctance Motor, Finite Element Method, Boundary Element Method, Static Torque.
Vol. 5. n. 2, pp. 514-520
Abstract - In this paper a new single-sensor-based maximum power point tracking (MPPT) technique is introduced for solar photovoltaic (PV) water pumping application. The system comprises a PV array, a DC/DC buck converter, a water storage tank, a DC motor-pump, and a digital MPPT controller. Hill climbing conventional method is employed to find and track the MPP using information obtained from a single voltage sensor. A comparison with conventional method which needs both voltage and current sensors is presented in both simulation and experimental results. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: DC/DC Buck Converter, MPPT, DC Motor-Pump, Single Sensor.
Vol. 5. n. 2, pp. 521-529
Abstract - This paper deals the integration of energy storage devices (Ultracapacitors and batteries) in wind energy applications, to absorb the short and long term fluctuations. The studied hybrid system includes a wind generator emulator, a diesel generator emulator, an Ultracapacitors module, a battery’s module and a programmable electric load. The originality of this contribution is related to wind power frequency distribution between the hybrid sources by using two low pass filters. The wind’s current is filtered to generate the reference values of the Ultracapacitors and battery’s currents. In this paper, the proposed strategy is detailed and the converters control methods are presented. An experimental tests bench is designed in the laboratory to validate the proposed energy management strategy. The control laws are implemented in Microchip Microcontroller (PIC18F4431). The performances of the energy management are illustrated through some simulations and experimental results. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Battery, Buck Converter, Buck-Boost Converter, Diesel Generator, Storage Devices, Ultracapacitors, Wind Power Generation.
Vol. 5. n. 2, pp. 530-535
Abstract - The main problem in parallel operation of batteries is how to divide load current equally between parallel branches. Since the study of load sharing needs an accurate analysis of batteries internal impedances, the electrochemical behavior of batteries are reviewed. In order to measure batteries’ internal impedances, a new simple method based on the electrochemical impedance spectroscopy (EIS) concept is deduced and it is verified by experimental results. Using the proposed method, the impedances of two similar 200Ah vented lead-acid batteries are measured and used to analyze the current sharing between batteries in parallel connection. Since the differences between batteries impedances leads to inequality in each parallel batteries the application of interphase transformer is introduced. The performance of proposed current sharing method is validated using experimental results. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Batteries, Current Sharing, Interphase Transformer.
Vol. 5. n. 2, pp. 536-541
Abstract - Control strategy that determines the overall efficiency of hybrid system plays a centre role in hybrid electric vehicle (HEV). The work in this paper presents a simulation of a Parallel Hybrid Vehicle controlled by sugeno-type fuzzy logic. The fuzzy logic controller is designed based on battery state of charge and the totally required output torque. The output of the controller is a coefficient which controls the torque of electric motor. For the purpose of achieving a better fuel economy, simulations are done with results that confirm the validity of the designed controller, which can be flexible to allow extension and reconfiguration. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Hybrid Electric Vehicle, Fuzzy Logic Controller, Power Conversion Efficiency.
Vol. 5. n. 2, pp. 542-551
Abstract - In a motor drive application, control and diagnostic informations measured by sensors are sent back from the motor to the power converter through a separated extra cabling. Each motor requires an extra cable dedicated for data transmission such as rotor speed, rotor position, temperature monitoring and vibrations measurements. These cables are long and expensive which can be problematic in terms of price and overall dimension. The aim of this paper is to study the feasibility of sending control and diagnostic information from the motor side back to the inverter through the power cable using the Power Line Communication technology. The main benefit lies on the fact of removing the extra cable dedicated for data transmission by fulfilling communication through the existing motor feeder cable. This technology exists already in domestic application through the electrical network 110-230V/50-60Hz where its reliability has been demonstrated. However the Pulse Width Modulation (PWM) signal is of higher frequency and higher amplitude than the electrical sinusoidal signal and it can affect badly on communication. According to this, this paper will underline the difficulties and limitations in communication over the PWM network and will discuss any possible way to overcome them. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Coupling Interface, IGBT Switches, Power Line Communication, PWM Network, OFDM Signal.
International Review of Electrical Engineering - Papers- Part B
by Mahdiyeh Eslami, Hussain Shareef, Azah Mohamed Vol. 5. n. 2, pp. 552-570
Abstract - Power demand has risen considerably in recent years, while the development of power generation and transmission has been seriously restricted due to limited resources and environmental limitations. Power system stabilizers (PSS) and flexible AC transmission system (FACTS) devices are applied to increase the system stability. Use of only conventional PSS in large multi-machine systems may not supply satisfactory damping for inter-area oscillations. In this situation, FACTS power oscillation damping controllers are efficient solutions. The literature shows an increasing interest in this topic for the last two decades, where the enhancement of system stability using FACTS controllers has been widely investigated. In addition coordination between PSS and FACTS controllers have been explored. This paper provides an extensive review on the research and improvements in the power system stability enhancement using PSS and FACTS controllers. Several technical publications related to FACTS installations have been highlighted and performance comparison of different FACTS controllers has been discussed. Moreover, some of the utility experience, real-world installations, and semiconductor technology development have been outlined. Applications of PSS and FACTS to other power system studies have been surveyed. About three hundred sixty research publications have been sorted and appended for a rapid reference. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: : Power System Stability, PSS, FACTS, SVC, TCSC, TCPS, STATCOM, SSSC, UPFC.
Vol. 5. n. 2, pp. 571-577
Abstract - This paper describes a novel design concept of power interfaces connecting distributed generators (DG) to the distribution networks. The proposed power interface is able to perform multiple compensating functions besides regulating the real power fed from DG systems. The hardware structure used in the proposed system is similar to the conventional static synchronous compensator (STATCOM), a shunt-type, converter-based flexible ac transmission systems (FACTS) device; however, its power rating is designed at the distribution level to facilitate the used of high frequency switching techniques. With the proposed control scheme, the key control functions of distribution STATCOM and active power filters (APF) can be integrated into a single DG hardware system. To demonstrate the feasibility of the proposed control scheme, performances in compensating load current harmonics and the reactive power compensation of the system are investigated. The feasibility and effectiveness of the proposed flexible power interface are verified by simulations and laboratory tests. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed Generator, Flexible Ac Transmission Systems, Reactive Power Compensation, Active Power Filter.
Vol. 5. n. 2, pp. 578-592
Abstract - The conventional protection in distribution networks is designed to operate for high fault current levels in radial networks, but during island operation of the microgrid high fault currents from the utility grid are not present. Also most of the distributed generation (DG) units that will be connected to the low voltage (LV) microgrid in the future are converter interfaced and have limited fault current feeding capabilities. This means that the traditional fuse protection of LV network alone is no longer applicable and new protection methods must be developed. In this paper new smart protection concept for LV microgrid is proposed in which for example LV feeders are protected in addition of traditional fuses with protective relays that have adaptive multi-criteria algorithms and fast standard IEC 61850 based communication capabilities. One of the most important issues is to ensure that the behavior that is required from DG units, including fault-ride-through (FRT) needs, during faults in microgrid during normal and island operation is compatible with the developed microgrid protection concept. The simulation studies done in the development of new protection concept were made with PSCAD simulation software. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Microgrid, Protection, Distributed Generation, Energy Storage, Smart Grids.
Vol. 5. n. 2, pp. 593-600
Abstract - Recent research has shown that installation of distributed generation (DG) units in the utility’s distribution system of a power network would lead to attainment of numerous potential benefits. To maximise these benefits, it is crucial to find the optimal number or size of DG units and their appropriate locations in power distribution systems, since siting DG units in improper locations could jeopardise the system operation. However, the task to determine the optimal size and sites of DG sources in power systems is not an easy one, due to a number of factors. In tackling this problem, many approaches have been proposed by various researchers in recent years. This paper presents a critical review of different methodologies employed in solving this optimisation problem. For ease of reference, and to facilitate understanding, this literature categorises and discusses the various existing approaches into five different major headings. They are: the analytical approaches, the meta-heuristics, the genetic algorithms (GAs) approach, the GA-hybrids, and finally those that are categorised as other approaches. The benefits, as well as the drawbacks of each approach are thoroughly examined in the paper. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed Generation, Optimal Placement, Genetic Algorithms, Meta-Heuristics, Analytical Approaches, GA-Hybrids.
Vol. 5. n. 2, pp. 601-607
Abstract - Reactive power dispatch is a multi constrained nonlinear multivariable optimization, problem. The objectives are to minimize real power losses and improve the voltage profile of a given electric power system by using a number of control tools such as switching VAr sources, changing generator voltages and adjusting transformer settings. By an optimal adjustment of these controllers, the optimal distribution of reactive power would minimize transmission losses. To solve this problem, this paper is concerned with the application of a hybrid formulation between particle swarm optimization and improved genetic algorithms with real coding. For the control variables, a mixed representation (continuous/discrete), is proposed. The method is tested on the Ward-Hale 6 bus system. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Improved Genetic Algorithms, Particle Swarm Optimization, Reactive Power Dispatch .
Vol. 5. n. 2, pp. 608-613
Abstract - In recent years, real power networks have experienced more low frequency oscillations. This paper proposes new multi objective decision making structure for Independent System Operator (ISO) of a competitive electricity market, in which the generation costs of a single auction market and power system damping factor are optimized together. In this process, the best tuning strategy for power system stabilizers, as the main device for damping factor improvement, is determined. Furthermore, the effects of using PSSs and their tuning can be evaluated. NSGA-II approach is used to solve the resulting multi objective optimization problem. The proposed method is tested on IEEE 39-bus system and results are reported. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Small Signal Stability, Multi-Objective Optimization, Power System Dynamic, Power System Stabilizer, NSGA-II.
Vol. 5. n. 2, pp. 614-618
Abstract - The active power loss minimization problem is formulated as a Optimal Reactive Power Flow (ORPF), including equality and inequality nonlinear constraints which represent the power system security conditions. The ORPF has been solved using the interior point method. The proposed methodology has been applied to minimize the active power loss of IEEE-57 bus test systems. Test results indicated that the convergence is facilitated and the number of iterations became smaller. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Load Flow, Active Power Loss Minimisation, Interior Point Method.
Vol. 5. n. 2, pp. 619-627
Abstract - This paper presents the measured impedance at the relaying point in the presence of Static Var Compensator (SVC), one of the shunt connected Flexible Alternating Current Transmission System (FACTS) devices, in the case of symmetrical (three phase) and asymmetrical (single phase to ground and phase to phase) faults. The presence of SVC on a transmission line has a great influence on the measured impedance at the relaying point. The measured impedance itself depends on the power system structural conditions, pre-fault loading, and especially the fault resistance. In the presence of SVC, its compensation current as well as its installation location affects the measured impedance and consequently the locus of the apparent impedance. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distance Protection, FACTS Devices, Locus Of The Apparent Impedance, Measured Impedance, SVC.
Vol. 5. n. 2, pp. 628-636
Abstract - Many large cities have their hybrid transmission and distribution networks, while traditionally, transmission and distribution state estimators are studied and developed separately. In order to achieve a global consistent state estimation solution, the balance transmission and unbalance distribution networks are studied as a whole in this paper. A novel master–slave-splitting (MSS) iterative method is developed for calculating large-scale and mixed state estimation (MSE) problem. In the MSS method, with introducing the boundary fictitious measurement, the MSE problem of large scale is split into a balanced transmission state estimation and many unbalanced distribution state estimation sub-problems of small scale. In order to fit the different features between balanced transmission and unbalanced distribution networks, each sub-problem can be solved with different algorithm. Several case studies are carried out, and the accuracy, convergence, efficiency and reliability of the proposed method are validated. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Mixed State Estimation (MSE), Integrated Power System, Energy Management System (EMS), Distribution Management System (DMS).
Vol. 5. n. 2, pp. 637-643
Abstract - Distributed generation (DG) units, based on their interfacing technology are divided into synchronous generator interfaced DG, asynchronous generator interfaced DG and inverter interfaced DG. In this paper, the voltage stability of power system with high penetration levels of the different DGs is investigated. Different penetration levels of DGs are considered and with each penetration level, the performance of the power system is studied and results are compared with the performance of the power system without any DG, to highlight the impacts of DGs on power system voltage stability. Simulation results will be provided in order to show the effectiveness of our studies. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed Generation, Voltage Stability, Voltage Source Inverter.
Vol. 5. n. 2, pp. 644-651
Abstract - This paper, presents a new methodology for the placement of multi-type FACTS devices in deregulated electricity market to enhance available transfer capability (ATC). The presentation of FACTS technology in power system network may be can effectively enhance system loadability. However, due to their high cost, the proper selection of the number and placement of these devices is required. In the proposed work, a swarm-based optimization technique, known as bees algorithm is used to optimize the various parameters involved in the introductions of FACTS devices in a power system. The parameters taken into considerations are the location of FACTS devices, their type and their corresponding setting. The optimal configuration will be the one that maximize the ATC between the source and sink area while keeping the power system operating within appropriate security limits. Four types of FACTS devices are included, namely: thyristor-controlled series compensator (TCSC), static VAR compensator (SVC), thyristor-controlled phase shift transformer (TCPST) and unified power flow controller (UPFC). The proposed technique has been tested on IEEE118- bus test systems. A Genetic Algorithms (GA) is prepared for validation purpose. The results obtained are very encouraging and compared with those obtained by GA. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: ATC, Bees Algorithm, TCSC, SVC, UPFC, TCPST, GA.
Vol. 5. n. 2, pp. 652-662
Abstract - Stability of a system is one of its most crucial yet largely hidden characteristic. Power systems, both ac and dc, face instability; with dc systems facing voltage instability only while ac systems have to confront frequency and rotor angle instability in addition to the voltage instability. Apparently, this makes dc systems easier to design since there is only one form of instability i.e. voltage instability which needs to be tackled. Yet this has proved a huge challenge and even now, a decade and a half after the beginning of active research for stabilizing a dc distributed power system, research efforts are still in progress. This paper attempts to present and compare some of the latest research techniques for dc distributed power system stability as well as briefly reviews the history of research efforts in this area. A short description of the dc distributed system paradigm along with its applications is also included in this paper. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Advanced Control Schemes, Distributed Power System, Stability.
Vol. 5. n. 2, pp. 663-670
Abstract - Loss
reduction and system upgrading postponement are two crucial factors
respectively in reducing the operational cost (current cost) and
deferring distribution companies (DISCO) going to the expense of
infrastructure development. Today, great attention has been paid to the
distributed generation as a tool affecting current and capital costs of
the companies by distribution systems programmers and designers. A main
problem is that the two objectives are not in full alignment. In one
hand, locating the DG, with the aim of loss reduction, does not result
in a maximum postponement of the system upgrading. On the other hand,
locating the DG, with the aim of postponing the system upgrading, does
not result in a maximum loss reduction. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed Generation, Distribution System, Reconfiguration.
Vol. 5. n. 2, pp. 671-682
Abstract - Electric
power utilities invest heavily on their IT infrastructures; however, a
large number of IT development projects fail. These failures are mostly
caused by unsystematic and ad hoc designs, which can be summarized as
lack of consistent design decision methods. This consistent design
decision method should include a well-aligned IT development plan,
considering requirements of the needed system. The literature shows the
positive effect of this alignment of the IT requirements with the
utility corporate policy, referred to as being Policy-Driven, here. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Policy-Driven Decision Making, Power Distribution Systems, IT Infrastructure, Utility Management Automation (UMA), Distribution Automation (DA), Architectural Design, Multi-Criteria Decision-Making (MCDM).
Vol. 5. n. 2, pp. 683-690
Abstract - Contingency screening and ranking is one of the most important issues for security assessment in the field of power system operation. The objective of contingency ranking is to quickly and accurately select a short list of critical contingencies from a large list of potential contingencies and rank them according to their severity. Then suitable preventive actions can be implemented considering these contingencies that are likely to affect the power system performance. In this paper a novel approach is presented for contingency ranking based on static security assessment (SSA). This method employs weighted performance index with the application of Fuzzy Logic based Analytical Hierarchy Process (FLAHP) in order to select appropriate weighting factors to be imposed. The proposed method is applied to IEEE 30 bus system and the results are presented. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Contingency Ranking, Static Security Assessment (SSA), Performance index (PI), Weighting Factor, Fuzzy Logic, Analytical Hierarchy Process (AHP).
Vol. 5. n. 2, pp. 691-697
Abstract - A calculation concept on exposure to non-sinusoidal magnetic fields has been evaluated and carried out for Static VAr Compensators (SVC). The calculation concept follows the guidelines published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Further, we present how the magnetic field and magnetic field exposure behaves inside the SVC and in the neighborhood. Because of high content of the magnetic field harmonics the guideline values are exceeded close to SVC components in areas where workers are usually doing for example maintenance works. The aim of this case study is to present guidance, proposals and advice for suppliers and clients of SVC units on how to carry out magnetic field calculations. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: SVC, Magnetic Field Harmonics, Exposure, Calculation, Guidance for Suppliers, Proposals for Clients.
Vol. 5. n. 2, pp. 698-708
Abstract - It is well known that the network variables and parameters contain sufficient information to obtain the most sensitive bus or line to the voltage collapse in power systems. Accordingly, there has been several static voltage stability indices developed for identifying the buses or lines on the verge of voltage collapse in the literature. In this paper, various voltage stability indices including those originally developed for transmission systems are first reviewed. Then, their adequacies are quantitatively evaluated on a modern distribution test system which has voltage controlled bus (PV-bus). From analyses, it is observed that most of the existing voltage stability indices would be inadequate for assessing the most sensitive bus or line on the verge of voltage collapse in such modern distribution systems. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Critical Bus, Modern Distribution Networks, Voltage Stability Indices, Voltage Collapse.
Vol. 5. n. 2, pp. 709-716
Abstract - Reliability of real large distribution network of a city was calculated based on probabilistic method taken into account in this paper. Four different methods were used to improve reliability. Analysis of voltage sag incidence rate was done, too. In studied case it was shown that how much using improvement methods of reliability can affect voltage sag incidence rate in networks. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Power Quality, Reliability, Distribution Network, Voltage Sag (Dip), Reliability Index, Digsilent Software.
Vol. 5. n. 2, pp. 717-725
Abstract - Neutral
conductor or network earthing can be considered as one of the effective
factors on power quality. Neutral conductor is used to maintain the
symmetrical components in load terminals in an acceptable level and to
minimize the common mode noise in steady state condition of system, so
network earthing has an important effect on voltage and temperature
stress reduction, equipments, safety and restricting short circuit
fault. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Active Earthing, Earth Fault, Grounding, Power Quality, Series Active Filter, Zero Sequence.
Vol. 5. n. 2, pp. 726-737
Abstract - The necessity for flexible electric systems, changing regulatory and economic scenarios, energy savings and environmental impact are providing impetus to the development of Distributed Generation (DG), which is predicted to play an increasing role in the electric power system of the future. The optimal placement and sizing of generation units on the distribution network has been continuously studied in order to achieve different aims. This paper describes planning of distribution systems in two scenarios. In the first scenario, optimal distributed generation allocation for voltage profile improvement, loss and Total harmonic Distortion (THD) reduction in distribution network has been implemented. Whereas, DG cannot reduce THD to the optimum range, in the second scenario an active filter and a capacitor is used to reduce THD as much as possible. Because of THD and Losses are based on different objective function, a “compromise programming” model that attains the “best compromise” among the conflicting objectives is introduced to overcome on this problem. Harmony Search Algorithm (HSA) was used as the solving tool, which referring two determined aim; the problem is defined and objective function is introduced according to losses, security and THD indices. The applied fast harmonic load flow method is based on the equivalent current injection that uses the bus-injection to branch-current (BIBC) and branch-current to bus-voltage (BCBV) matrices which were developed based on the topological structure of the distribution systems. This method is executed on 12 bus harmonic unbalanced distribution system and show robustness of this method in optimal and fast placement of DG, efficiency for improvement of voltage profile, reduction of power losses and THD. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Unbalanced Radial Distribution Network, Distributed Generation, Harmonic Filter, Harmonic Load Flow, Loss Minimization, Total Harmonic Distortion (THD), Harmony Search Algorithm (HSA), Optimum Location.
Vol. 5. n. 2, pp. 738-747
Abstract - A new scheme for controlling point of common coupling (PCC) for large scale Photovoltaic (PV) power plants with reactive power compensation is presented. The objective is to realize a reliable bulk renewable photovoltaic power supply for all kinds of grid loads. This source can be operated independently or in conjunction with grid. The Maximum Power Point Tracking Technique (MPPT) and Inverter control logic ensure maximum utilization of the PV array, resulting in optimum operational power. Apart from feeding active power into the grid, the system can also provide reactive power compensation. Active and reactive power can be independently controlled by selecting appropriate modulation index and inverter reference parameters. This leads to the idea of defining PV as a PŪ Bus bar in grid. Peculiarities of the novel proposed idea, including power and control circuits, DIgSILENT simulation results are presented and discussed in detail. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: MPPT, PCC, Inc-Cond, Voltage Profile, Load Profile, PŪ Control, PQ Mode.
Vol. 5. n. 2, pp. 748-757
Abstract - In this paper, the size of a stand-alone wind/PV/battery system is optimized. The hybrid system is consisting of three major power sources: wind turbine generator, photovoltaic arrays, and storage batteries that the characteristics of components are commercially available. This study is performed for a region in North-West of Iran. The optimization problem is subject to economic and technical constraints. System costs involve investments, replacements, and operation and maintenance as well as loss of load costs. The technical constraint, related to system reliability, is expressed by the equivalent loss factor. The reliability index is calculated from component’s failure that is including of wind turbine, PV array, battery and inverter failure. In this study, size of components related to three different systems is evaluated and they are compared with each other. The simulation results indicate that the hybrid system can be the best alternative for this region that has minimum costs and can satisfy the constraints. Also, the error of measurement propagation for hybrid system is calculated. In this study particle swarm optimization algorithm is used for optimal sizing of system’s components. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Error Propagation, Hybrid Power System, Particle Swarm Optimization, Reliability, Wind Power.
Vol. 5. n. 2, pp. 758-765
Abstract - High
voltage insulators must have high superficial resistance to prevent
current conductance in undesired path. In spite of considering
appropriate superficial resistance during design and manufacturing,
accumulation of pollution on insulators in wet condition along with
inappropriate insulation profile design result in electrical breakage
and repetitive outages. Operation records, high outage rates due to
pollution and short intervals of insulator washing in southern regions
of Iran confirm the problem. Thus, appropriate design of insulation in a
power network, especially in heavy contaminated regions is very crucial.
An efficient and appropriate insulation profile design should be
provided based on situation and perfect knowledge of system parameters
such as pollution. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Field Studies, Insulator, Optimum Profile, Pollution, Simulation.
Vol. 5. n. 2, pp. 766-772
Abstract - This paper presents a novel three-phase symmetrical voltage multiplier circuit for X-ray power supply. The proposed voltage multiplier is formed by connecting three single-phase symmetrical voltage multiplier circuits in series and driving them by a three-phase ac power source. The proposed voltage multiplier has several advantages over the conventional single-phase voltage multiplier and previously proposed three-phase voltage multiplier. It has very fast dynamic response, three times smaller output voltage ripple and nine times smaller voltage drop compared to single-phase symmetrical voltage multiplier. It also has faster dynamic response and smaller voltage drop compared to previously proposed three-phase voltage multiplier. The number of components required to implement the proposed three-phase voltage multiplier is same as required for conventional single-phase voltage multiplier, unlike the previously proposed three-phase voltage multiplier which needs three-times larger number of components. This makes the proposed voltage multiplier compact, cost-effective and efficient. The feasibility of the proposed three-phase voltage multiplier is verified both by simulation and experimental results. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Voltage Multiplier, X-ray Power Supply, DC High Voltage, Low Voltage Ripple, Low Voltage Drop, Fast Dynamic Response.
Vol. 5. n. 2, pp. 773-778
Abstract - Monitoring the depth of anesthesia is vital for anesthesiologists. Several methods have been suggested to determine a quantitative index for depth of anesthesia. In this paper an efficient method based on Wigner-Ville transform is proposed to achieve a better estimation of the depth index during the surgery. Wigner-Ville distribution represents the EEG signal windows during the surgery into time-frequency domain and the depth index is extracted from this space. As far as the amplitude of EEG signal is not important for calculating anesthesia depth, we decline the effect of signal amplitude in different windows while frequency content of signal does not change. The proposed method leads to increase the depth index robustness and provides very similar results to the Bispectral index (BIS). Ten subjects are participated in this study and the isoflurane drug is used during the surgery. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Depth Of Anesthesia, EEG Signal, Smoothed Pseudo Wigner-Ville Distribution.
Vol. 5. n. 2, pp. 779-784
Abstract - Two planar layers of materials with fixed thicknesses are placed on a perfect electric conductor and a plane wave is normally incident on them. The reflected power is minimized with respect to the real and imaginary parts of ε and μ at several discrete frequencies in a specified frequency bandwidth. Then some particular functions (such as polynomials)are fitted to the pairs of data (fi,εi) and (fi,μi) to derive the specified dispersion relations. This procedure is in contrast to the determination of parameters in the common dispersion relations (such as Lorentz, Drude and resonance). Very deep levels of reduction of reflected powers are thus achievable by assuming arbitrary dispersion relations as opposed to the common ones. The physical realization of synthesized dispersion relations is not addressed here and should be subject of further research on effective media. The determination of dispersion relations for the minimization of reflected powers from single layer or multilayer structures could potentially have effective applications for absorbing boundary conditions (ABCs)and perfect matched layers (PMLs). Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Dispersion Relation, Radar Absorbing Materials, Radar Cross Section, Multilayered Structures, Genetic Algorithm.
Vol. 5. n. 2, pp. 785-792
Abstract - This paper presents a rigorous synthesis of circular arrays of printed antennas using a hybrid fuzzy-genetic algorithm. Fuzzy logic based controllers are applied to fine-tune dynamically the crossover and mutation probability in the genetic algorithms, in an attempt to improve the algorithm performance. The FGA approach is compared with the Standard Genetic Algorithm(SGA). Included synthesis example clearly demonstrates that while the SGA approach gives satisfactory solutions for the problem, the FGA method usually performs significantly better. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fuzzy Genetic Algorithms, Population Diversity Measurements, Circular Antennas Array, Synthesis, Fuzzy Controller.
Vol. 5. n. 2, pp. 793-802
Abstract - Power generation and power network distribution are nowadays going through heterogeneous infrastructures. Therefore standardization is an important and urgent issue in order to provide portability of cost effective system hardware and software components. One decade ago an attempt in this direction was made by introducing the design approach relative to Power Electronics Building Blocks (PEBB). However, a need arise to unify different PEBB points of views concerning the architecture and the interfaces. Authors' previous work has shown the importance of adopting a Universal control strategy within the frame of a global Universal Control Protocol (UCP) for PEBB. In this study, based on the PEBB layered architecture inspired from the OSI model, standardization issues are discussed. In addition, the UCP strategy is validated for a wide range of converters and compared with the conventional one. To validate the decoupling characteristic between different parts of the LA, different control algorithm, control strategies, and power electronics topologies are interchanged for the same application. In this study, the paper focuses on the universal aspect of the interface between the application and the hardware control layers. Another step ahead for the UCP is validated by showing the flexibility of interconnecting PEBBs in a power network. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Distributed Power Systems, Layered Architecture, PEBB, Universal Control Protocol.
Vol. 5. n. 2, pp. 803-811
Abstract - Analog multiplier is an important building block for many analog computational applications. In this paper, a new compact, low power structure and low voltage CMOS analog multiplier is proposed. The proposed structure incorporates a cross-coupled squarer circuit. The most important features of this topology are low power consumption and high band-width that makes it suitable for use in high frequency applications. All of these are implemented using a compact circuit. The circuit is designed and analyzed in 0.18µm CMOS process model and the key features like bandwidth and THD are extracted. Simulation results for the circuit with a 1.2V single supply show a very low power consumption and better band-width with respect to comparable structures. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: CMOS Analog Multiplier, Four Quadrant, Cross-Coupled Squarer Circuit.
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