• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.3
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• pp.263-272
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• 1990

In the variable speed driving system of a three phase induction motor controlled by a PWM inverter, the output terminal contains considerable amount of harmonic components of the voltage waveform due to the switching action of semiconductor devices, causing torque ripples, acoustic noise and oscillation of the motor. This paper describes a new algorithm which eliminates the harmonics and controls the fundamental voltage in three phase PWM inverter output waveform. The new algorithm utilizes the technique of particular harmonics elimination (PHE) by walsh series in three phase PWM inverter output waveform. A microprocessor (8086 CPU)-controlled three phase induction motor system is described to realize this algorithm. The system is designed for 3 phase output voltage in the 1-60Hz interval where 5th and 7th harmonics, and 5th, 7th, 11th, and 13th harmonics are eliminated. Also, the fundamental wave amplitude is designed to be proportional to the output frequency. The performance of the proposed method shows sufficient elimination of the harmonics and also reduction of computation time which determines switching pattern. The proposed PWM pattern by Walsh series, is effective not only to induction motors but also to other electromagetic equipments such as voltage regulators and UPS.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.339-346
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• 2005

It is complex to realize the reference voltage vector by the space vector PWM method in three-leg two-phase inverter In this paper a new PWM technique for three-leg two-phase inverter fed two-phase induction motor is poroposed assuming that three-leg two-phase inverter is equivalent circuit for 'four-leg two-phase inverter with the connected two windings'. From assumption, six sectors are decreased to four sectors, and simple sinusoidal PWM method instead of SVPWM is applied to three-leg two-phase inverter. Also, the switching pattern to determine the switching periods at each sector is proposed. Practical verification of theoretical predictions is presented to confirm the capabilities of the new techniques.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.227-230
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• 1993

Recently, the development of novel control methodology enables us to improve the performance of AC-machine drives by using pulse width modulation (PWM) technique. Usually, the dynamic characteristic of induction motor (IM) has been represented by the 5-th order nonlinear differential equation. This dynamics, however, can be reduced to 3-rd order dynamics by applying direct control of IM input current. This methodology concludes that it is much easier to control IM by means of the field-oriented methods employing the current controller. Therefore a precise current control is crucial to achieve a high control performance both in dynamic and steady state operations. This paper presents an adaptive fuzzy current controller with artificial neural network (ANN) for field-oriented controlled IM. This new control structure is able to adaptively minimize a current ripple while maintaining constant switching frequency. Especially the proposed controller employs neuro-computing philosophy as well as adaptive learning pattern recognizing principles with respect to variations of the system parameters. The proposed approach is applied to the IM drive system, and its performance is tested through various simulations. Simulation results show that the proposed system, compared among several known classical methods, has a superb performance.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.430-433
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• 2001

When the vector control, which does not need a speed signal from a mechanical speed sensor, it is possible to reduce the cost of the control equipment and to improve the control performance in many industrial application. This paper describes a rotor speed identification method of induction motor based on the theory of flux model reference adaptive system. The estimator execute the rotor speed identification so that the vector control of the induction motor may be achieved. The improved auxiliary variable of the two model are introduced In perform accurate rotor speed estimation. The control system is composed of the PI controller for speed control and current controller using space voltage vector PWM technique. High speed calculation and processing for vector control is carried out by TMS320C31 digital signal processor. Validity of the proposed control method is verified through simulation and experimental result.

• Journal of Power Electronics
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• v.15 no.2
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• pp.544-554
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• 2015

This paper presents a steady-state operation analysis of full-bridge series-resonant inverters focusing on the distorted load current due to low-quality-factor resonant circuits in induction heating and other applications. The regions of operation based on the zero-voltage switching (ZVS) and non-zero-voltage switching (NON-ZVS) operations of the asymmetrical voltage-cancellation control technique are identified. The effects of a distorted load current under a wide range of output powers are also analyzed for achieving a precise ZVS operating region. An experimental study is performed with a 1kW prototype. Simulation and experimental studies have confirmed the validity of the proposed method. An efficiency comparison between the variable frequency method and the conventional fixed-frequency method is provided.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.195-197
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• 2005

This paper is proposed adaptive fuzzy neural network(AFNN) and artificial neural network(ANN) based on the vector controlled induction motor drive system. The hybrid combination of fuzzy control and neural network will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed control and estimation of speed of induction motor using fuzzy and neural network. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The error between the desired state variable and the actual one is back-propagated to adjust the rotor speed. so that the actual state variable will coincide with the desired one. This paper is proposed the experimental results to verify the effectiveness of the new method.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.2
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• pp.10-19
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• 1990

The tempering behavoirs of 0.45% carbon steel treated by automatic progressive high frequency induction hardening equipment have been investigated. In order to examine the correlation of hardness with both tempering temperature and time, simple regression analysis has been made using the statistical quality control package. The maximum surface hardness value of induction hardened zone and its effective hardening depth have been determined to be Hv 810 and 0.76mm, respectively. The hardness obtained after tempering has been shown to vary lineary with tempering time at six different temperatures. The activation energies during tempering have been calculated to be 25.34kcal/mole, 32.73kcal/mole and 49.24kcal/mole for HRcs 60, 50 and 40, respectively, showing that tempering process occurs by a complex mechanism, The tempering hardness equation of $H=90.113{\sim}4.531{\times}10^{-3}$ [T(11.996+log t)] has proved to be in a reasonably good agreement with experimently determined data and it is also expected to be useful for the determination of tempering treatment conditions to obtain a required hardness value.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.507-515
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• 2004

With the advent of fast power devices, the high dv/dt voltage produced by PWM inverts have been found to cause EMI noise, shaft voltage and bearing current. This paper describes the application of newly developed Conducted EMI reduction SVPWM technique in induction motor drives. The newly developed common mode voltage reduction SVPWM technique don't use any zero-vector states for inverter control, hence it can restrict the common mode voltage more than conventional PWM technique. The validity of the proposed technique by software approach is verified through simulation and experimental results.

• The Journal of Korean Obstetrics and Gynecology
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• v.24 no.3
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• pp.28-47
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• 2011

Objectives: This study was performed to investigate the effects of Angelicae gigantis Radix (AGR) which is one of the most useful herbal-drug to treat patients with Polycystic Ovary Syndrome (PCOS) in Oriental medicine on gene expression of ovary tissue. Methods: The effects of AGR on gene expression of ovary tissue resected from PCOS induced rats using single injection of $\ss$-Estradiol 17-valerate (EV) was measured using microarray technique, and the functional analysis on these genes was conducted. Results: Total 2,812 genes were up-regulated or down-regulated, 1,421 genes were up-regulated, 1,391 genes were down-regulated by induction of PCOS. Up-regulated genes were mainly involved in biological function such as cell signalling pathways and inflammatory response. Expression levels of 1,442 genes were restored to those of naive animals by administration of AGR. 558 genes were restored to those of naive animals, which were lowered by induction of PCOS. 884 genes were lowered to naive levels, which were elevated by induction of PCOS. The functions of restored genes were partially involved in the restoration of expression levels, which were changed by induction of PCOS. Especially, up-regulated gene by induction of PCOS were mainly involved in these changes. These results mean restorative effects of AGR on damaged functions by induction of PCOS. The network of total protein interactions was measured using cytoscape program, and some key molecules, such as IRS2, MCM10, ORC2L related in up-regulated genes, CTBP2, CD44, RHOA, related in down-regulated genes that can be used for elucidation of therapeutical mechanism of medicine in future were identified. Conclusion: Restored genes by AGR were thought to have common pathways related in regulation of gene expressions. Especially, genes in restored expression levels by AGR, which were up-regulated by induction of PCOS, were regulated by 9 of common transcription factors, genes in restored expression levels by AGR, which were down-regulated by induction of PCOS, were involved in 25 of common transcription factors.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.1
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• pp.29-34
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• 2005

The wound induction motor can provide high starting torque and reduced starting current simultaneously by inserting large resistor externally when starting. And this technique is one of the well known methods among the induction motor starting methods and generally used for heavy load starting such as crane and cement factories. The conventional PI controller has been widely used in industrial application due to the simple control algorithm and is generally used for control of current torque, position, and speed for the wound induction motor drive system. However, the conventional control system for wound induction motor may result in poor performance because sensors have to be used but are often limited by the environmental condition. Recently, to overcome these problems, many sensorless vector control methods for the wound induction motor have been studied. This paper presents a MRAS method for sensorless vector control of the wound induction motor drive. In the conventional MRAS method, in low frequency, the stator resistance variation may result in poor performance. Therefore, this paper presents a MRAS method with stator and rotor resistance tuning for sensorless vector control of the wound induction motor to overcome several shortages of the conventional MRAS caused by parameter variation and to enhance the robustness of the sensorless vector control. The validity and effectiveness of the proposed method is verified through digital simulation.