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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Electrical Engineering and Technology
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The Korean Institute of Electrical Engineers
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Volume 11, Issue 4 - Jul 2016
Volume 11, Issue 3 - May 2016
Volume 11, Issue 2 - Mar 2016
Volume 11, Issue 1 - Jan 2016
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Analysis of an Active Superconducting Current Controller (ASCC) Considering the Transient Stability and OCR Operation in Transmission and Distribution Systems
Gusheh, Ahmad Ghafari ; Soreshjani, Mohsen Hosseinzadeh ; Rahat, Omid ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 543~550
DOI : 10.5370/JEET.2016.11.3.543
The Active Superconducting Current Controller (ASCC) is a new type of Superconducting Fault Current Limiters (SFCL) which can limit the fault current in different modes. It also has the particular abilities of compensating active and reactive powers for electrical networks. In this paper, it is confirmed that the performance of ASCC in different operating modes introduces a limiting impedance in series with the network which can even degrade the transient stability and the operation of the Over-Current Relays (OCR) employed in a power system. In addition, the model of a three-phase ASCC is simulated, and the effect of descriptive modes on the current limiting level is investigated. For the transient stability analysis, a single machine-infinite bus system is tested, and the effect of operation modes is studied based on an equal area criterion obtaining the critical time and the critical angle. Modifying the setting parameters of OCR such as time dial and pick-up current, the protective coordination is also studied in different operating modes.
Optimal Placement of Distributed Generators in Radial Distribution System for Reducing the Effect of Islanding
K, Narayanan. ; Siddiqui, Shahbaz A. ; Fozdar, Manoj ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 551~559
DOI : 10.5370/JEET.2016.11.3.551
The present trend of increasing the penetration levels of Distributed Generator (DG) in the distribution network has made the issue of Islanding crucial for the reliable operation of the network. The islanding, if not detected early may lead to the collapse of the system as it can drive the distribution system to the cascaded failure. In this paper, an extensive study of the effect of DG placement and sizing is performed by dividing the system into different zones to obtain a reduced effect of islanding. The siting and sizing of DG is carried out to improve the overall voltage profile or/and reduction in active power loss using two stage Genetic Algorithm (GA). In the first stage a basic knockout selection is considered and the best population is taken for next stage, where roulette selection for crossover and mutation is performed for optimal placement and sizing of DGs. The effect of the islanding, due to load variations is reduced by optimal siting and sizing of DG. The effectiveness of the proposed scheme is tested on the IEEE 33 and 69 radial bus systems and the results obtained are promising.
Power System Harmonic Estimation Based on Park Transform
Chen, Ya ; Ji, Tianyao ; Li, Mengshi ; Wu, Qinghua ; Wang, Xuejian ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 560~574
DOI : 10.5370/JEET.2016.11.3.560
This paper presents a novel method for power system harmonic estimation based on the Park transform. The proposed method firstly extends the signal to a group of three-phase signals in a-b-c coordinate. Then, a linear fitting based method is adopted to estimate the fundamental frequency. Afterwards, the Park transform is utilized to convert the three-phase signals from a-b-c coordinate to d-q-0 coordinate. Finally, the amplitude and phase of a harmonic component of interest can be calculated using the d-axis and q-axis components obtained. Simulation studies have been conducted using matrix laboratory (MATLAB) and power system computer aided design/electromagnetic transients including direct current (PSCAD/EMTDC). Simulation studies in MATLAB have considered three scenarios, i.e., no-frequency-deviation scenario, frequency-deviation scenario and the scenario in the presence of inter-harminics. The results have demonstrated that the proposed method achieves very high accuracy in frequency, phase and amplitude estimation under noisy conditions, and suffers little influence of the inter-harmonics. Moreover, comparison studies have proved that the proposed method is superior to FFT and Interpolated FFT with the Hanning Window (IpFFTHW). Finally, a popular case in PSCAD/EMTDC has been employed to further verify the effectiveness of the proposed method.
Reliability Evaluation of a Distribution System with wind Turbine Generators Based on the Switch-section Partitioning Method
Wu, Hongbin ; Guo, Jinjin ; Ding, Ming ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 575~584
DOI : 10.5370/JEET.2016.11.3.575
Considering the randomness and uncertainty of wind power, a reliability model of WTGs is established based on the combination of the Weibull distribution and the Markov chain. To analyze the failure mode quickly, we use the switch-section partitioning method. After defining the first-level load zone node, we can obtain the supply power sets of the first-level load zone nodes with each WTG. Based on the supply sets, we propose the dynamic division strategy of island operation. By adopting the fault analysis method with the attributes defined in the switch-section, we evaluate the reliability of the distribution network with WTGs using a sequential Monte Carlo simulation method. Finally, using the IEEE RBTS Bus6 test system, we demonstrate the efficacy of the proposed model and method by comparing different schemes to access the WTGs.
A New Algorithm to Reduce the Mal-Operation of DOCR in Bi-directional Power Distribution Systems
Jang, Su-Hyeong ; Oh, Joon-Seok ; Jeong, Ui-Yong ; Kim, Jae-Eon ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 585~591
DOI : 10.5370/JEET.2016.11.3.585
DOCR can be used to efficiently increase the reliability and to protect the bi-directional D/L(Distribution Lines). As more DG(Distributed Generation)s attempt to connect the bi-directional D/L, there is an increasing need for studies of how to use DOCR installed in the D/L. This paper investigates the operating principles of DOCR and presents the results an effect of sequence and fault impedance in L-L(Line to Line) fault. An advanced DOCR operating algorithm is proposed to reduce the mal-operation of conventional DOCR. The proposed algorithm is applied to the bi-directional power flow system and shows that it decreases the mal-operation of DOCR through the computer simulation.
New Modeling of Switching Devices Considering Power Loss in Electromagnetic Transients Program Simulation
Kim, Seung-Tak ; Park, Jung-Wook ; Baek, Seung-Mook ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 592~601
DOI : 10.5370/JEET.2016.11.3.592
This paper presents the modeling of insulated-gate bipolar transistor (IGBT) in electromagnetic transients program (EMTP) simulation for the reliable calculation of switching and conduction losses. The conventional approach considering the physical property of switching devices requires many attribute parameters and large computation efforts. In contrast, the proposed method uses the curve fitting and interpolation techniques based on typical switching waveforms and a user-defined component with variable resistances to capture the dynamic characteristics of IGBTs. Therefore, the simulation time can be efficiently reduced without losing the accuracy while avoiding the extremely small time step, which is required in simulation by the conventional method. The EMTP based simulation includes turn-on and turn-off transients of IGBT, saturation state, forward voltage of free-wheeling diode, and reverse recovery characteristics, etc. The effectiveness of proposed modeling for the EMTP simulation is verified by the comparison with experimental results obtained from practical implementation in hardware.
New Simulation Method of Flashover Rate by Connection of EMTP and MATLAB
Seo, Hun-Chul ; Han, Joon ; Choi, Sun-Kyu ; Lee, Byung-Sung ; Kim, Chul-Hwan ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 602~608
DOI : 10.5370/JEET.2016.11.3.602
Because of the random characteristics of lightning, the Monte Carlo method is applied to estimate the flashover rate due to lightning, however, the simulations using previous methods are difficult to both beginner and expert in power corporations. Therefore, this paper proposes the new and easy method to simulate the flashover rate by connection of electromagnetic transients program (EMTP) and MATLAB. The magnitude of a lightning strike is based on a curve measured in the field, while the classification of direct and indirect lightning depends on the striking distance. In a Korean distribution system, the flashover rate induced by lightning is simulated using proposed method. Simulations of the footing resistance according to the existence of an overhead ground wire (OHGW) are performed and the simulation results are discussed. The simulation results are compared with findings obtained with the IEEE Flash 2.0 program.
An Off-line Maximum Torque Control Strategy of Wound Rotor Synchronous Machine with Nonlinear Parameters
Wang, Qi ; Lee, Heon-Hyeong ; Park, Hong-Joo ; Kim, Sung-Il ; Lee, Geun-Ho ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 609~617
DOI : 10.5370/JEET.2016.11.3.609
Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.
Analysis and Application of Repetitive Control Scheme for Three-Phase Active Power Filter with Frequency Adaptive Capability
Sun, Biaoguang ; Xie, Yunxiang ; Ma, Hui ; Cheng, Li ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 618~628
DOI : 10.5370/JEET.2016.11.3.618
Active power filter (APF) has been proved as a flexible solution for compensating the harmonic distortion caused by nonlinear loads in power distribution power systems. Digital repetitive control can achieve zero steady-state error tracking of any periodic signal while the sampling points within one repetitive cycle must be a known integer. However, the compensation performance of the APF would be degradation when the grid frequency varies. In this paper, an improved repetitive control scheme with frequency adaptive capability is presented to track any periodic signal with variable grid frequency, where the variable delay items caused by time-varying grid frequency are approximated with Pade approximants. Additionally, the stability criterion of proposed repetitive control scheme is given. A three-phase shunt APF experimental platform with proposed repetitive control scheme is built in our laboratory. Simulation and experimental results demonstrate the effectiveness of the proposed repetitive control scheme.
State-of-Charge Balancing Control of a Battery Power Module for a Modularized Battery for Electric Vehicle
Choi, Seong-Chon ; Jeon, Jin-Yong ; Yeo, Tae-Jung ; Kim, Young-Jae ; Kim, Do-Yun ; Won, Chung-Yuen ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 629~638
DOI : 10.5370/JEET.2016.11.3.629
This paper proposes a State-of-Charge (SOC) balancing control of Battery Power Modules (BPMs) for a modularized battery for Electric Vehicles (EVs) without additional balancing circuits. The BPMs are substituted with the single converter in EVs located between the battery and the inverter. The BPM is composed of a two-phase interleaved boost converter with battery modules. The discharge current of each battery module can be controlled individually by using the BPM to achieve a balanced state as well as increased utilization of the battery capacity. Also, an SOC balancing method is proposed to reduce the equalization time, which satisfies the regulation of a constant DC-link voltage and a demand of the output power. The proposed system and the SOC balancing method are verified through simulation and experiment.
Development and Performance Investigation on a 60kW Induction Motor for EV Propulsion
Chun, Yon-Do ; Park, Byoung-Gun ; Kim, Dong-Jun ; Choi, Jae-Hak ; Han, Pil-Wan ; Um, Sukkee ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 639~643
DOI : 10.5370/JEET.2016.11.3.639
This paper introduces the development process and investigation of a 60kW induction motor for electric vehicles. We present performance improvement in the induction motor of electric vehicle using copper die-casting based on a multi-gate process. Copper die-casting motors can reduce the size of the motor, the loss of the rotor, and material costs. We also introduce electromagnetic, thermal, mechanical design and analysis results that satisfy the design and the performance requirements. In order to analyze losses accurately of induction motor, commercial finite element analysis is done considering PWM voltage and thermal characteristics by using lumped-circuit parameters. Experimental tests are also carried out to validate the traction motor design.
Improved Single-Stage AC-DC LED-Drive Flyback Converter using the Transformer-Coupled Lossless Snubber
Jeong, Gang-Youl ; Kwon, Su-Han ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 644~652
DOI : 10.5370/JEET.2016.11.3.644
This paper presents an improved single-stage ac-dc LED-drive flyback converter using the transformer-coupled lossless (TCL) snubber. The proposed converter is derived from the integration of a full-bridge diode rectifier and a conventional flyback converter with a simple TCL snubber. The TCL snubber circuit is composed of only two diodes, a capacitor, and a transformer-coupled auxiliary winding. The TCL snubber limits the surge voltage of the switch and regenerates the energy stored in the leakage inductance of the transformer. Also, the switch of the proposed converter is turned on at a minimum voltage using a formed resonant circuit. Thus, the proposed converter achieves high efficiency. The proposed converter utilizes only one general power factor correction (PFC) control IC as its controller and performs both PFC and output power regulation, simultaneously. Therefore, the proposed converter provides a simple structure and an economic implementation and achieves a high power factor without the need for any separate PFC circuit. In this paper, the operational principle of the proposed converter is explained in detail and the design guideline of the proposed converter is briefly shown. Experimental results for a 40-W prototype are shown to validate the performance of the proposed converter.
Capacitance Estimation Method of DC-Link Capacitors for BLDC Motor Drive Systems
Moon, Jong-Joo ; Kim, Yong-Hyu ; Park, June-Ho ; Kim, Jang-Mok ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 653~661
DOI : 10.5370/JEET.2016.11.3.653
This paper proposes a capacitance estimation method of the dc-link capacitor for brushless DC motor (BLDCM) drive systems. In order to estimate the dc-link capacitance, the BLDCM is operated in quadrant-II or -IV among four-quadrant operation. Quadrant-II and -IV are called reverse braking and forward braking, respectively. During the braking operation of the BLDCM, the capacitor is charged by the phase current and then the voltage is increased during the braking operation time. The capacitor current and voltage can be obtained by using the phase current sensor of BLDCM and the dc-link voltage sensor. The capacitance and be easily obtained by the voltage equation of the capacitor. The proposed method guarantees the reliable and simple calculation of the dc-link capacitance without additional hardware system except several the sensors already installed for the motor control system. The effectiveness of the proposed method is verified through both the simulation and experimental results.
Improved Sliding Mode Controller for Shunt Active Power Filter
Sahara, Attia ; Kessal, Abdelhalim ; Rahmani, Lazhar ; Gaubert, Jean-Paul ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 662~669
DOI : 10.5370/JEET.2016.11.3.662
In this work, nonlinear control of a three-phase shunt active power filter (SAPF) has been studied and compared to classical control based on proportional integral regulator. The control strategy is based on the direct current method using sliding mode control (SMC), where the aim is to regulate the average voltage across the dc bus of the inverter. Details are given for the control algorithm; the controller is comprised of a current loop which utilizes a hysteresis controller to generate the gating signals for the switching devices, and a nonlinear controller based on SMC law which is different from classical laws based on error between reference and measured output voltage of the inverter. Sliding surface applied in this work contains the whole of state variables, in order to ensure full control of the system behavior in the presence of disturbances that affect the supply source, the load parameters or the reference value. The designed controller offers advantage that it can gives the improvement of dynamic and static performances in cases of large disturbances. A comparison of the effects of PI control and SMC on the APF response in steady stat, under line variations, load variations, and different component variations is performed.
Hybrid Pulse Width Modulation Strategy for Wide Speed Range in IPMSM with Low Cost Drives
Ahn, Han-woong ; Go, Sung-chul ; Lee, Ju ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 670~674
DOI : 10.5370/JEET.2016.11.3.670
The control performance of hybrid PWM inverter using a phase current measurement is presented in this paper. The hybrid PWM technique consists of space vector pulse width modulation (SVPWM) and six-step voltage control operation. The SVPWM is performed to reduce the harmonic components in the low speed region, and the six-step modulation is applied to increase the maximum speed of the IPMSM in the high speed region. Therefore, it is possible to obtain a great performance in both the low speed range and high speed range. However, the six-step modulation cannot be completely implemented, since the inverter that includes the lag-shunt sensing method has an immeasurable current region. In this paper, a quasi-six-step modulation using a modified voltage vector is proposed. The validity and usefulness of the proposed PWM technique is verified by MATLAB/Simulink and experimental results.
A Cost-Effective, Single-Phase Line-Interactive UPS System that Eliminates Inrush Current Phenomenon for Transformer-Coupled Loads
Bukhari, Syed Sabir Hussain ; Atiq, Shahid ; Lipo, Thomas A. ; Kwon, Byung-il ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 675~682
DOI : 10.5370/JEET.2016.11.3.675
Sudden voltage drops and outages frequently disturb the operation of sensitive loads for domestic, commercial, and industrial use. In some cases, these events may even impair the functioning of relevant equipment. To maintain power under such conditions, a UPS system is usually installed. Once a disturbance happens at the grid side, the line-interactive UPS system takes over the load to prevent an interruption. But, due to magnetic saturation of the transformer, a significant inrush current may occur for the transformer-coupled loads during this transition. The generation of such transient currents may in turn decrease the line voltage and activates over-current protecting devices of the system. In this work, a cost-effective, line-interactive UPS system is proposed that eliminates the inrush current phenomenon associated with transformer-coupled loads. The strategy was implemented by connecting a standard current-regulated voltage source inverter (CRVSI) to the secondary winding of the load transformer. During any transient condition at the grid side, the load current is monitored and regulated to achieve either seamless compensation of the load current or complete transferal of load from grid to the inverter. Experimental results were obtained for a prototype under all possible operating conditions so as to validate the performance of the proposed topology.
Investigation of Degradative Signals on Outdoor Solid Insulators Using Continuous Wavelet Transform
Uzunoglu, Cengiz Polat ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 683~689
DOI : 10.5370/JEET.2016.11.3.683
Most outdoor solid insulators may suffer from surface degradations due to non-stationary currents that flow on the insulator surface. These currents may be classified as leakage, discharge and tracking currents due to their disturbing potencies respectively. The magnitude of these currents depends on the degree of the contamination of surface. The leakage signals are followed by discharge signals and tracking signals which are capable of forming carbonized tracking paths on the surface between high voltage and earth contacts (surface tracking). Surface tracking is one of the most breakdown mechanisms observed on the solid insulators, especially polymers which may cause severely reduced lifetime. In this study the degradations observed on polyester resin based insulators are investigated according to the IEC 587 Inclined Plane Test Standard. The signals are monitored and recorded during tests until surface tracking initiated. In order to prevent total breakdown of an insulator, early detection of tracking signals is vital. Continuous Wavelet Transform (CWT) is proposed for classification of signals and their energy levels observed on the surface. The application of CWT for processing and classification of the surface signals which are prone to display high frequency oscillations can facilitate real time monitoring of the system for diagnosis.
Investigation on the Dielectric, Physical and Chemical Properties of Palm Oil and Coconut Oil under Open Thermal Ageing Condition
Mohamad, Nur Aqilah ; Azis, Norhafiz ; Jasni, Jasronita ; Kadir, Mohd Zainal Abidin Ab ; Yunus, Robiah ; Ishak, Mohd Taufiq ; Yaakub, Zaini ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 690~698
DOI : 10.5370/JEET.2016.11.3.690
In this paper, a study is carried out to investigate the dielectric, physical and chemical properties of Palm Oil (PO) and Coconut Oil (CO) under open thermal ageing condition. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The ageing experiment was carried out at 85 ℃ and 115 ℃ for 1, 3, 5, 7 and 14 days. Several parameters were measured such as AC breakdown voltage, dielectric dissipation factor, relative permittivity, resistivity, viscosity, moisture and acidity throughout the ageing duration. Based on the study, it is found that there are no significant changes on the AC breakdown voltages and relative permittivities for both RBDPO and CO. At ageing temperature of 115℃, there are clear reduction trends of dielectric dissipation factor for CO and resistivities for most of RBDPO. On the other hand, no clear trends are observed for viscosities, moisture and acidities of RBDPO and CO throughout the ageing duration.
Partial Discharge Characteristics in LLDPE-Natural Rubber Blends: Correlating Electrical Quantities with Surface Degradation
Aulia, Aulia ; Ahmad, Mohd Hafizi ; Abdul-Malek, Zulkurnain ; Arief, Yanuar Z. ; Lau, KwanYiew ; Novizon, Novizon ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 699~706
DOI : 10.5370/JEET.2016.11.3.699
Partial discharges (PD) lead to the degradation of high voltage cables and accessories. PD activities occur due to the existence of impurities, voids, contaminants, defects and protrusions during the manufacture and installation of power cables. Commonly, insulation failures occur at cable joints and terminations, caused by inhomogeneous electric field distributions. In this work, a blend of natural rubber (NR) and linear low density polyethylene (LLDPE) was investigated, and the optimal formulation of the blend that could resist PD was discussed. The experiments were conducted under a constant high voltage stress test of 6.5 kV AC and the magnitude of partial discharge activities was recorded using the CIGRE method II. Pattern analysis of PD signals was performed along with the interpretation of morphological changes. The results showed that the addition of 10 wt% of NR and 5 wt% of Alumina Trihydrate (ATH) provided promising results in resisting PD activities. However, as the NR content increased, more micropores existed, thus resulting in increased PD activities within the samples.
Low Frequency Vibration Energy Harvester Using Stopper-Engaged Dynamic Magnifier for Increased Power and Wide Bandwidth
Halim, Miah Abdul ; Kim, Dae Heum ; Park, Jae Yeong ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 707~714
DOI : 10.5370/JEET.2016.11.3.707
We present a piezoelectric energy harvester with stopper-engaged dynamic magnifier which is capable of significantly increasing the operating bandwidth and the energy (power) harvested from a broad range of low frequency vibrations (<30 Hz). It uses a mass-loaded polymer beam (primary spring-mass system) that works as a dynamic magnifier for another mass-loaded piezoelectric beam (secondary spring-mass system) clamped on primary mass, constituting a two-degree-of-freedom (2-DOF) system. Use of polymer (polycarbonate) as the primary beam allows the harvester not only to respond to low frequency vibrations but also generates high impulsive force while the primary mass engages the base stopper. Upon excitation, the dynamic magnifier causes mechanical impact on the base stopper and transfers a secondary shock (in the form of impulsive force) to the energy harvesting element resulting in an increased strain in it and triggers nonlinear frequency up-conversion mechanism. Therefore, it generates almost four times larger average power and exhibits over 250% wider half-power bandwidth than those of its conventional 2-DOF counterpart (without stopper). Experimental results indicate that the proposed device is highly applicable to vibration energy harvesting in automobiles.
PSO-Based Optimal PI(D) Controller Design for Brushless DC Motor Speed Control with Back EMF Detection
Kiree, Chookiat ; Kumpanya, Danupon ; Tunyasrirut, Satean ; Puangdownreong, Deacha ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 715~723
DOI : 10.5370/JEET.2016.11.3.715
This paper proposes a design of optimal PI(D) controller for brushless DC (BLDC) motor speed control by the particle swarm optimization (PSO), one of the powerful metaheuristic optimization search techniques. The proposed control system is implemented on the TMS320F28335 DSP board interfacing to MATLAB/SIMULINK. With Back EMF detection, the proposed system is considered as a class of sensorless control. This scheme leads to the speed adjustment of the BLDC motor by PWM. In this work, the BLDC motor of 100 watt is conducted to investigate the control performance. As results, it was found that the speed response of BLDC motor can be regulated at the operating speed of 800 and 1200 rpm in both no load and full load conditions. Very satisfactory responses of the BLDC system can be successfully achieved by the proposed control structure and PSO-based design approach.
Sampled-Data Observer-Based Decentralized Fuzzy Control for Nonlinear Large-Scale Systems
Koo, Geun Bum ; Park, Jin Bae ; Joo, Young Hoon ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 724~732
DOI : 10.5370/JEET.2016.11.3.724
In this paper, a sampled-data observer-based decentralized fuzzy control technique is proposed for a class of nonlinear large-scale systems, which can be represented to a Takagi-Sugeno fuzzy system. The premise variable is assumed to be measurable for the design of the observer-based fuzzy controller, and the closed-loop system is obtained. Based on an exact discretized model of the closed-loop system, the stability condition is derived for the closed-loop system. Also, the stability condition is converted into the linear matrix inequality (LMI) format. Finally, an example is provided to verify the effectiveness of the proposed techniques.
Dynamic Simulation of Modifiable Bipedal Walking on Uneven Terrain with Unknown Height
Hong, Young-Dae ; Lee, Ki-Baek ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 733~740
DOI : 10.5370/JEET.2016.11.3.733
To achieve bipedal walking in real human environments, a bipedal robot should be capable of modifiable walking both on uneven terrain with different heights and on flat terrain. In this paper, a novel walking pattern generator based on a 3-D linear inverted pendulum model (LIPM) is proposed to achieve this objective. By adopting a zero moment point (ZMP) variation scheme in real time, it is possible to change the center-of-mass (COM) position and the velocity of the 3-D LIPM throughout the single support phase. Consequently, the proposed method offers the ability to generate a modifiable pattern for walking on uneven terrain without the necessity for any extra footsteps to adjust the COM motion. In addition, a control strategy for bipedal walking on uneven terrain with unknown height is developed. The torques and ground reaction force are measured through force-sensing resisters (FSRs) on each foot and the foot of the robot is modeled as three virtual spring-damper models for the disturbance compensation. The methods for generating the foot and vertical COM of 3-D LIPM trajectories are proposed to achieve modifiable bipedal walking on uneven terrain without any information regarding the height of the terrain. The effectiveness of the proposed method is confirmed through dynamic simulations.
A Sufficient Condition for the Feedback Quasilinearization of Control Mechanical Systems
Chang, Dong Eui ; Song, Seong-Ho ; Kim, Jeom Keun ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 741~745
DOI : 10.5370/JEET.2016.11.3.741
We derive a sufficient condition for feedback quasilinearizability of control mechanical systems and apply it to show the feedback quasilinearizability of the Acrobot system.
Dilution of Precision Relationship between Time Difference of Arrival and Time of Arrival Techniques with No Receiver Clock Bias
Choi, Heon Ho ; Jin, Mi Hyun ; Lim, Deok Won ; Lee, Sang Jeong ; Park, Chansik ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 746~750
DOI : 10.5370/JEET.2016.11.3.746
Dilution of Precision (DOP), as a measure of positioning accuracy, is an essential factor. Therefore, the DOP relationship between systems is very important. In this paper, the DOP relationship between TDOA and TOA in systems lacking clock bias is derived analytically and verified experimentally. Also, using those of earlier studies, the DOP relationship in each of defined systems is derived analytically.
Dynamic Simulation of Modifiable Walking Pattern Generation to Handle Infeasible Navigational Commands for Humanoid Robots
Hong, Young-Dae ; Lee, Ki-Baek ; Lee, Bumjoo ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 751~758
DOI : 10.5370/JEET.2016.11.3.751
The modifiable walking pattern generation (MWPG) algorithm can handle dynamic walking commands by changing the walking period, step length, and direction independently. When an infeasible command is given, the algorithm changes the command to a feasible one. After the feasibility of the navigational command is checked, it is translated into the desired center of mass (CM) state. To achieve the desired CM state, a reference CM trajectory is generated using predefined zero moment point (ZMP) functions. Based on the proposed algorithm, various complex walking patterns were generated, including backward and sideways walking. The effectiveness of the patterns was verified in dynamic simulations using the Webots simulator.
Acoustic Sources Localization in 3D Using Multiple Spherical Arrays
Wang, Fangzhou ; Pan, Xi ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 759~768
DOI : 10.5370/JEET.2016.11.3.759
Direction of arrival (DOA) estimation of multiple sources using sensor arrays has been widely studied in the last few decades, particularly, the spherical harmonic analysis utilizing a spherical array. Both the number of sensors on the aperture and size of the sphere can affect the estimation accuracy dramatically. However, those two factors are conflicted to each other in a single spherical array. In this paper, a multiple spherical arrays structure is proposed to provide an alternative design to the traditional single spherical array for the spherical harmonic decomposition, to obtain better localization performance. The new structure consists of several identical spheres in a given area, and the microphones are placed identically on each sphere. The spherical harmonic analysis algorithm using the new multiple array structure for the problem of multiple acoustic sources localization is presented. Simulation results show that the multiple spherical arrays can provide a more accurate direction of arrival (DOA) estimation for the multiple sources than that of a single spherical array, distinguish several adjacent sources more efficiently, and reduce the number of microphones on each sphere without decreasing its’ estimation accuracy.
Improved Mutual MRAS Speed Identification Based on Back-EMF
Zheng, Hong ; Zhao, Jiancheng ; Liu, Liangzhong ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 769~774
DOI : 10.5370/JEET.2016.11.3.769
In the design of sensorless control system for induction motor, high-precision speed estimation is one of the most difficult problems. To solve this problem, the common method is model reference adaptive method (MRAS). MRAS requires accurate motor parameters to estimate rotor speed precisely. However, when motor is running, the variety of temperature and magnetic saturation will lead to the change of motor parameters such as stator resistance and rotor resistance, which will lower the accuracy of the speed estimation. To improve the accuracy and rapidity of speed estimation, this paper analyses the mutual MRAS speed identification based on rotor flux linkage, and proposes an improved mutual MRAS speed identification based on back-EMF. The improved method is verified by Simulink simulation and motor experimental platform based on DSP2812. The results of simulation and experiment indicate that the method proposed by this paper can significantly improve the accuracy of speed identification, and speed up the response of identification.
Research on the Correlation of Control Malfunction with Induced Voltage of Control Signal Line According to Voltage Change of a Power Line
Kang, Dong-Woo ; Kim, In-Gun ; Ham, Sang-Hwan ; Kim, Sung-Yul ; Bae, Sungwoo ; Kim, Dae-Nyeon ; Lee, Ju ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 775~780
DOI : 10.5370/JEET.2016.11.3.775
This induced voltage measurement test and electromagnetic field simulation are related to the possibility of control signal malfunction by power line. Through an experiment, this research analyzed whether the voltage causing control malfunction according to the on/off status of power permitted to power line was induced to control signal line. Also, the research calculated the voltage induced to control signal line and examined the phenomenon by conducting an electro-magnetic field-specific simulation through the finite element method for the cable model used in the experiment.
A 3-D Steady-State Analysis of Thermal Behavior in EHV GIS Busbar
Lei, Jin ; Zhong, Jian-ying ; Wu, Shi-jin ; Wang, Zhen ; Guo, Yu-jing ; Qin, Xin-yan ;
Journal of Electrical Engineering and Technology, volume 11, issue 3, 2016, Pages 781~789
DOI : 10.5370/JEET.2016.11.3.781
Busbar has been used as electric conductor within extra high voltage (EHV) gas insulated switchgear (GIS), which makes EHV GIS higher security, smaller size and lower cost. However, the main fault of GIS is overheating of busbar connection parts, circuit breaker and isolating switch contact parts, which has been already restricting development of GIS to a large extent. In this study, a coupled magneto-flow-thermal analysis is used to investigate the thermal properties of GIS busbar in steady-state. A three-dimensional (3-D) finite element model (FEM) is built to calculate multiphysics fields including electromagnetic field, flow field and thermal field in steady-state. The influences of current on the magnetic flux density, flow velocity and heat distribution has been investigated. Temperature differences of inner wall and outer wall are investigated for busbar tank and conducting rod. Considering the end effect in the busbar, temperature rise difference is compared between end sections and the middle section. In order to obtain better heat dissipation effect, diameters of conductor and tank are optimized based on temperature rise simulation results. Temperature rise tests have been done to validate the 3-D simulation model, which is observed a good correlation with the simulation results. This study provides technical support for optimized structure of the EHV GIS busbar.