• Journal of Power Electronics
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• v.18 no.5
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• pp.1424-1433
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• 2018

This paper presents a novel space vector pulse-width modulation (SVPWM) to synthesize an arbitrary non-sinusoidal phase voltage. The key of the proposed method is that the switching vectors used to comprise the reference vectors in the ${\alpha}_1-{\beta}_1$ frame and the ${\alpha}_3-{\beta}_3$ frame are decoupled. In the ${\alpha}_1-{\beta}_1$ frame, the reference vector is comprised by near two large vectors. The corresponding vector comprised by the two vectors in the ${\alpha}_3-{\beta}_3$ frame is considered as a disturbance, which is restrained by close-loop control. In the ${\alpha}_3-{\beta}_3$ frame, there are two methods to comprise the reference vector. Method I is a near two middle vectors method. Method II uses near four vectors (two middle and two little vectors). The proposed SVPWM using decoupled switching vectors can guarantee a maximum modulation index in the ${\alpha}_1-{\beta}_1$ frame. The effectiveness of the proposed method is verified by simulated and experimental results under various operation conditions.

• Journal of Power Electronics
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• v.19 no.2
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• pp.487-496
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• 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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.88-96
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• 2000

The instantaneous power theory have been considered as efficient theory in recent years, because it is easier to understand numerical representation and more soft to control PWM power converter on $\alpha$-$\beta$ stationary reference frame. From the forgoing theory, with regard to the calculating process of compensating reference current, there are many induced components of current/ power, and these components have consequently influence on physical interpretation of instantaneous power theory. Especially, beginners for studing the instantaneous power theory don't have enough informations for standard waveform of induced $\alpha$-$\beta$ components. Therefore, this paper describes simulation works using MATLAB/SIMULINK for $\alpha$-$\beta$ space trajectories and waveforms of $\alpha$-$\beta$ current and power components, induced from the instantaneous power theory. It is respected that the results in this paper are serviceable as basic information to assist beginner for studing the instantaneous power theory.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1746-1752
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• 2014

This paper presents an application of proportional-resonant (PR) current controllers in modular multilevel converter-high voltage direct current (MMC-HVDC) system under unbalanced voltage conditions. The ac currents are transformed and controlled in the stationary reference frame (${\alpha}{\beta}$-frame). Thus, the complex analysis of the positive and negative sequence components in the synchronous rotating reference frame (dq-frame) is not necessary. With this control method, the ac currents are kept balanced and the dc-link voltage is constant under the unbalanced voltage fault conditions. The simulation results based on a detailed PSCAD/EMTDC model confirm the effectiveness of the proposed control method.

• Journal of Aquaculture
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• v.17 no.1
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• pp.62-68
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• 2004

A cDNA encoding the masu salmon, Oncorhynchus masou, estrogen receptor $\alpha$ (msER$\alpha$) was cloned from the pituitary gland by polymerase chain reaction (PCR). This cDNA contains an open reading frame encoding 513 amino acid residues, and the calculated molecular weight of this protein is about 56,430 Dalton. The amino acid sequences of the DNA binding and ligand binding domains of msER$\alpha$ showed high homology to those of other fish species (84-100%). Reverse transcription PCR analysis showed that the mRNA level of msER$\alpha$ in the pituitary was slightly higher in estradiol-17$\beta$(E2) injected masu salmon than that of control fish. To test the biological activity of msER$\alpha$, the cDNA was ligated to a mammalian expression vector and transfected into a gonadotrope-derived cell line, L$\beta$T2, with a reporter plasmid including estrogen responsive element. Expression of the reporter protein, luciferase, was E2 and msER$\alpha$-dependent. The masu salmon ER$\alpha$ is structurally conserved among teleost species and functions as a transcriptional activator in the pituitary cells.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.107-114
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• 2014

This paper applies a compensated low pass filter (LPF) to current measurements for permanent magnet synchronous motor (PMSM) drives. The noise limits the bandwidth of current controllers and has more adverse influences on control performances under the light load condition because of the low signal-to-noise ratio. In order to eliminate the noise sensitivity, this paper proposes a digital LPF with a compensator of gain attenuation and phase delay which are unacceptable in current information for PMSM drives. Characteristics of the proposed LPF are analyzed in comparison with the general LPFs. The compensated LPF is basically designed by the orthogonal property of the measured currents in the ${\alpha}{\beta}$ stationary reference frame. In addition, an implementation issue of the proposed method is discussed. Experimental results using the proposed method show improvements of the current control performance from two perspectives, rapid step responses and reductions of harmonic distortion.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.65-75
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• 2005

Purpose: To understand genetic differences and similarities between mucolipidosis and control. Methods: Using the fibroblast of the mucolipidosis II and control, forward and reverse subtracted libraries were constructed. Among these clones, we investigated mutations in the GNPTA (MGC4170) gene, which codes for the ${\alpha}/{\beta}$ subunits of phosphotransferase, and in the GNPTAG gene, which codes for the ${\gamma}$ subunits in 5 Korean patients with mucolipidosis type II or IIIA. Result: Several differentially expressed cDNAs were cloned and their sequences were determined. Mutation analysis of the interested gene, GNPTA was performed and we identified 7 mutations in the GNPTA gene, but none in the GNPTAG gene. The mutations in type II patients included p.Q104X(c.310C>T), p.R1189X(c.3565C>T), p.S1058X(c.3173C>G), p.W894X(c.2681G>A) and p.H1158fsX15(c.3474_3475delTA), all of which are non-sense or frame shift mutations. However, a splicing site mutation, IVS13+1G>A (c.2715+1G>A) was detected along with a non-sense or a frame shift mutation (p.R1189X or p.E858fsX3(c.2574_2575delGA)) in two mucolipidosis type IIIA patients. Conclusion: This report shows that mutations in the GNPTA gene coding for the ${\alpha}{\beta}$subunits of phosphotransferase, and not mutations in the GNPTAG gene, account for most of mutations found in Korean patients with mucolipidosis type II or IIIA.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.264-271
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• 2014

Virtual synchronous generator (VSG) in single-phase to interface distributed renewable energy resources is investigated in this paper. Mathematical models and numerical analysis are utilized to illustrate the features of the VSG. Enhanced control strategy is presented to ensure the performance of the VSG. Besides, a second order generalized integer (SOGI) is employed to calculate the instantaneous output power of the VSG in virtual ${\alpha}{\beta}$ frame. By the means of a phase-locked loop based scheme, the VSG can seamlessly transform between islanded and grid-tied modes, which can meet the requirements of micro-grid. At last, the validation and the proposed approach are verified by the simulated results using PSCAD/EMTDC.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.4
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• pp.201-207
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• 2005

This paper has investigated the sensorless vector control method of induction motor based on the stator flux oriented voltage equation and the digital low pass filter (LPF) with compensator of phase/gain. The Proposed vector control method is easy to decide the stator reference voltages and control of motor, since it is based on stator flux vector But this method has sensitive structure to excessive sensor noise and PWM pulsating components of stator currents because the measured stator currents are directly used to compensate the internal resistive voltage drop at the determination of stator reference voltages. To eliminate the noise sensitive of proposed vector drive, this paper propose the digital LPF with compensator of phase/gain base on orthogonal property of stator current vector in stationary $\alpha$, $\beta$ reference frame. The proposed methods have been simulated and implemented on a sensorless vector drive for 750W three-phase induction motor. The simulation and experimental results demonstrate effectiveness of the proposed methods.

• Journal of Power Electronics
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• v.15 no.1
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• pp.190-201
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• 2015

This paper uses the switching function approach to present a simple state model of the Vienna-type rectifier. The approach introduces the relationship between the DC-link neutral point voltage and the AC side phase currents. A novel direct power control (DPC) strategy, which is based on the sliding mode control (SMC) for Vienna I rectifiers, is developed using the proposed power model in the stationary ${\alpha}-{\beta}$ reference frames. The SMC-based DPC methodology directly regulates instantaneous active and reactive powers without transforming to a synchronous rotating coordinate reference frame or a tracking phase angle of grid voltage. Moreover, the required rectifier control voltages are directly calculated by utilizing the non-linear SMC scheme. Theoretically, active and reactive power flows are controlled without ripple or cross coupling. Furthermore, the fixed-switching frequency is obtained by employing the simplified space vector modulation (SVM). SVM solves the complicated designing problem of the AC harmonic filter. The simplified SVM is based on the simplification of the space vector diagram of a three-level converter into that of a two-level converter. The dwelling time calculation and switching sequence selection are easily implemented like those in the conventional two-level rectifier. Replacing the current control loops with power control loops simplifies the system design and enhances the transient performance. The simulation models in MATLAB/Simulink and the digital signal processor-controlled 1.5 kW Vienna-type rectifier are used to verify the fast responses and robustness of the proposed control scheme.