• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.9
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• pp.600-608
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• 1988

Although the structure of brushless dc motor is similar to that of a Permanent magnet synchronous motor, its torque-speed characteristcis are the same as those of a permanent magmet dc motor. The brushless dc motor drive systemcomposed of power converter including inverter, rotor positioning sensor and controller has been investigated for the purpose of position control when the motor is fed by a current controlled voltage source inverter. The equivalent transformation of a brushless dc motor into an separately exited dc motor has been possible with the vector control (field oriented control) technique. It is shown in this paper that the position control of a brushless dc mitor can be done fairly accurately only using q-axis current.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.2
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• pp.51-58
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• 2001

This paper proposes a new strategy to estimate the rotor flux of an induction machine for the direct field oriented control. Electrical model of the induction machine presents the basic idea based on observer structure, which is composed of voltage model and current model. But the former has the defects in low speed range, the latter has the defects of sensitivity to machine parameters. In spite of these shortcomings, the closed loop flux observer based on two models has been prevalent estimation method for the direct field oriented control. In this paper, generalized analysis method named "observer characteristic function method"is proposed to analyze the kinds of the linear flux observers in unified form. With the observer characteristic function, the estimated rotor flux error involved in the classical methods can be easily clarified. Moreover, the novel rotor flux observer based on this analysis is also presented and the effectiveness of the observer has been verified by the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.268-272
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• 1989

To avoid the use of position sensor or flux sensor in a field oriented induction machine drive system, the terminal quantities are often used to estimate the rotor flux. Since the estimation involves the leakage inductance of the machine, the performance of such systems is sensitive to the variations of leakage. Since estimation of the stator flux is independent of the leakage, the steady state performance of the stator flux oriented system is insensitive to the leakage inductance. In this paper, the torque response of stator flux oriented system is compared to that of rotor flux oriented system by digital simulation. And induction motor sensor less speed control by stator flux oriented method is developed. The performance of the speed estimation is showed by digital simulation.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.412-414
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• 1996

The rotor resistance variation has a large effect on the field oriented control system of induction machine. In this paper, the adaptation technique based on MRAC is used to identify the rotor resistance variation. The criterion function used in the adaptation algorithm is the error function of the two reactive powers of the induction motor. The one is obtained from the voltages and the currents of the stator of the induction motor. And the other is estimated from the rotor flux and stator current. We simulated this control system operated by field oriented control and assured the robustness of the induction motor control system against the rotor resistence variation.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.546-551
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• 2001

This paper considers the design technique of the real-time control algorithm to implement the electronic interlocking system which is the most important station control system in railway signal field. The proposed technique consists of the structure design and the detail design which are based on the ROOM(Real-Time Object-Oriented Modeling) This proposed technique is applied to the typical station model in order to prove the validity as verifying the performance of the modeled station.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.675-682
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• 2000

An easier implementation method of the field oriented control of induction machine using Matlab/Simulink and dSpace board is proposed in this paper. The total system for the control of induction motor is modeled with the help of Matlab/Simulink. These models consist of induction motor block, SVPWM inverter block and control algorithm block, etc. And this system is simultaneously simulated and experimented in Matlab/Simulink environment with dSpace borad (DS1102). It is possible that Matlab and dSpace board compiler can make $^'{\ast}.c'\;and\;^'{\ast}.obj'$ file of models designed in Matlab/Simulink environment automatically. Both Simulation and experimental results are given.

• Journal of Power Electronics
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• v.11 no.2
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• pp.120-131
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• 2011

This paper proposes two control strategies for the bidirectional Z-source inverters (BZSI) supplied by batteries for electric vehicle applications. The first control strategy utilizes the indirect field-oriented control (IFOC) method to control the induction motor speed. The proposed speed control strategy is able to control the motor speed from zero to the rated speed with the rated load torque in both motoring and regenerative braking modes. The IFOC is based on PWM voltage modulation with voltage decoupling compensation to insert the shoot-through state into the switching signals using the simple boost shoot-through control method. The parameters of the four PI controllers in the IFOC technique are designed based on the required dynamic specifications. The second control strategy uses a proportional plus resonance (PR) controller in the synchronous reference frame to control the AC current for connecting the BZSI to the grid during the battery charging/discharging mode. In both control strategies, a dual loop controller is proposed to control the capacitor voltage of the BZSI. This controller is designed based on a small signal model of the BZSI using a bode diagram. MATLAB simulations and experimental results verify the validity of the proposed control strategies during motoring, regenerative braking and grid connection operations.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.19-20
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• 2003

Helicobasidium mompa Tanaka and Resellinia necatrix Prillieux cause violet root rot and white root rot of various crops, respectively. Intensive cultural practices, such as the use of dwarf stock, glasshouse cultivation, etc., predispose plants to the diseases. The diseases can be controlled only by biennial drench of 50100L of chemicals for each tree. Biocontrol with soil microorganisms proved ineffective under field conditions. Long-term control may be hampered by the perennial growth of hosts and by the difficulty in the establishment of antagonists in soil. Crop rotation or soil amendment is not applicable, either. Fungal viruses with dsRNA genome (Buck 1986) are promising against root diseases of fruit trees since they exist within the cytoplasm of fungal hyphae and need no effort to help them persist in the field. The viruses are considered to spread though the network of fungal mycelia in the soil once they enter the fungal cytoplasm. Here, we present preliminary results from a project to control the root diseases of fruit trees with dsRNA.(중략)

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.365-373
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• 1996

This paper presents the effects of rotor time constant variation and the on-line tuning algorithm of the rotor time constant. If the value of the rotor time constant is set incorrectly, the IFOC (Indirect Field Oriented Control)scheme exhibits deteriorated performance according to the wrong slip command. These variation effects of the rotor time constant are caused by the slip calculator where it is known that the rotor time constant play an important role in the aligned rotor flux. Using the two torque angles (stationary torque angle, rotating torque angle), the variation of the rotor time constant is identified, and the rotor time constant of the controller is tuned to the proper value of the machine. As the result, with the proposed algorithm, the dynamics of the deteriorated IFOC system, where the rotor time constant is varied, is improved. For the purpose of the validity of this proposed algorithm, the computer simulations and the experiments have been performed and the explanation of the results is presented. (author). refs., figs., tab.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.330-335
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• 2013

This paper performs two kinds of Field-Oriented Control (FOC) for dual three phase permanent magnet synchronous motor (DTP-PMSM).The first is based on vector space decomposition to study the effect of current harmonics on electromechanical energy conversion. And the second presents the coupling relations between two sets of windings using two d-q transformation. And then this paper has deeply studied the differences between these two strategies, the different effect on the control of harmonic current and the reason for these differences. MATLAB-based Simulation studies of a 3KW DTP-PMSM are carried out to verify the analysis of differences between the two FOC strategies.