• Journal of Power Electronics
• /
• 제7권2호
• /
• pp.97-108
• /
• 2007

This paper describes simple control structures for a vector controlled stand-alone induction generator (IG) for use under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with a newly designed phase locked loop circuit. The required reactive power for the variable speed IG is supplied by means of a PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery, to reduce the rating of the PWM converter while using only three sensors and to eliminate the harmonics generated by the PWM converter. These proposed schemes can be used efficiently for variable speed wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good AC and DC voltage regulation.

• Journal of Power Electronics
• /
• 제19권2호
• /
• pp.487-496
• /
• 2019

For a solid-state transformer (SST), some factors, such as signal delay, switching loss and differences in the system parameters, lead to unbalanced DC-link voltages among the cascaded H-bridges (CHB). With a control method implemented in the ${\alpha}{\beta}$ frame, the DC-link voltages are balanced, and the reactive power is equally distributed among all of the H-bridges. Based on the ${\alpha}{\beta}$ frame control, the system can achieve independent active current and reactive current control. In addition, the control method of the high-voltage stage is easy to implement without decoupling or a phase-locked loop. Furthermore, the method can eliminate additional current delays during transients and get the dynamic response rapidly without an imaginary current component. In order to carry out the controller design, the vector refactoring relations that are used to balance DC-link voltages are derived. Different strategies are discussed and simulated under the unbalanced load condition. Finally, a three-cell CHB rectifier is constructed to conduct further research, and the steady and transient experimental results verify the effectiveness and correctness of the proposed method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
• /
• pp.37-42
• /
• 1990

In order to obtain optimal design criteria and operating parameters, a Single-sided Linear Induction Motor (SLIM) is analysed by using a 2-D finite element method with magnetic and current vector potential. In the analysing procedures, the governing equation is derived from Maxwell's equation combined with the magnetic vector potential. As a forcing term, 3-phase voltage source is employed using the Kirchhoff's voltage law in order to look into effects of the unbalanced 3-phase currents and air gap flux density. Also, 2ndary eddy current distribution, longitudinal end and transverse edge effects are in turns visualized by flux lines in 3 different analysing planes as functions of frequency and input power.

• Journal of electromagnetic engineering and science
• /
• 제7권1호
• /
• pp.7-11
• /
• 2007

PCB Power-Bus (comprising power/ground planes) impedance and fields are evaluated by an efficient series expansion method that is suggested in this paper. It is used to investigate the structure's radiated emission(RE) levels and find acceptable ways of loading the power/ground planes such as decoupling capcitor(DeCap)s, balanced feeding and slits, in order to reduce the interferences. Also, the calculations and measurements of a proposed geometry are verified by vector fitting as a analysis model to check the behavior of the slit.

• Journal of Power Electronics
• /
• 제16권4호
• /
• pp.1367-1374
• /
• 2016

This paper presents a discrete-time version of voltage and current limited operation using an enhanced direct torque and flux control method for interior permanent magnet synchronous motor (IPMSM) drives. A command voltage vector for airgap torque and stator flux regulation can be uniquely determined by the finite-settling-step direct torque and flux control (FSS-DTFC) algorithm under physical constraints. The proposed command voltage vector trajectories can be developed to achieve the maximum inverter voltage utilization for the discrete-time current limit (DTCL)-based FSS-DTFC. The algorithm can produce adequate results over a number of the potential secondary upsets found in the steady-state current limit (SSCL)-based DTFC. The fast changes in the torque and stator flux linkage improve the dynamic responses significantly over a wide constant-power operating region. The control strategy was evaluated on a 900W IPMSM in both simulations and experiments.

• 전기학회논문지
• /
• 제58권6호
• /
• pp.1130-1137
• /
• 2009

This paper describes a scaled model development of PMSG wind power system using wind turbine simulator and matrix converter. The wind turbine simulator, which consists of an induction motor with vector drive, calculates the output torque of a specific wind turbine using simulation software and sends the torque signal to the vector drive after scaling down the calculated value. The operational feasibility of interconnected PMSG system with matrix converter was verified by computer simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was conformed by experimental works with a laboratory scaled-model of wind power system. The simulation and experimental results confirm that matrix converter can be effectively applied for the PMSG wind power system.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2008년도 추계학술대회 논문집
• /
• pp.327-331
• /
• 2008

The problems of power factor and harmonics are occurred in converter system which used to SCRs and diodes as power semiconductor devices IGBT was solved that problem, maintain the input line current with sinusoidal wave current of input power source voltage. In this paper, three phase AC to DC boost converter that operates with unity power factor and sinusoidal input currents is presented. The current control of the converter is based on the space vector PWM strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector PWM strategy for current control was materialized as a digital control method. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the dc link.

• 제어로봇시스템학회논문지
• /
• 제6권7호
• /
• pp.551-558
• /
• 2000

In this paper a systematic approach to automatic classificationi of power system harmonic disturbances is proposed where the proposed approach consists of the following three steps:(i) detecting and localizing each harmonic disturbance by applying discrete wavelet transform(DWT) (ii) extracting an efficient feature vector from each detected disturbance waveform by utilizing FFT and principal component analysis (PCA) along with Fisher's criterion and (iii) classifying the corresponding type of each harmonic disturbance by recognizing the pattern of each feature vector. To demonstrate the performance and applicability of the proposed classification procedure some simulation results obtained by analyzing 8-class power system harmonic disturbances being generated with Matlab power system blockset are also provided.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제54권2호
• /
• pp.71-80
• /
• 2005

This paper presents the position sensorless vector control of a cylindrical permanent magnet synchronous motor(PMSM) in the field weakening region. The position sensorless algorithm using an instantaneous reactive power of the PMSM is proposed. An instantaneous reactive power can be obtained from the vector product of rotor currents and back emf of the PMSM. Back emf includes the information of rotor speed. So the estimated speed can be yielded from the voltage equation of the PMSM. In other words, the estimated speed is compensated by using an instantaneous reactive power. To extend the speed range of the PMSM in the constant horsepower region, the field weakening control is applied. The proposed algorithm is not affected by mechanical motor parameters because the mechanical equation is not used. The effectiveness of the proposed algorithm is verified by the experimental results.

• Journal of Electrical Engineering and Technology
• /
• 제13권4호
• /
• pp.1715-1723
• /
• 2018

This work investigates the performance of fully complex- valued radial basis function network(FC-RBF) and complex extreme learning machine (CELM) based neural approaches for classification of power quality disturbances. This work engages the use of S-Transform to extract the features relating to single and combined power quality disturbances. The performance of the classifiers are compared with their real valued counterparts namely extreme learning machine(ELM) and support vector machine(SVM) in terms of convergence and classification ability. The results signify the suitability of complex valued classifiers for power quality disturbance classification.