• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.649-652
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• 1992

ECR(Electron Cyclotron Resonance) occure at ${\omega}_c$=${\omega}$, ${\omega}_c$:electron cycltron frequency, ${\omega}$:electromagnetic wave frequency. ECR system have several merit, 1) power transefer efficiency 2) low neutral gas pressure (below 1 mTorr) 3) high plasma density($10^{12}$ $cm^{-3}$). It is applicated variously in the field of semiconductor and new materials as the manufacturing equipment. Magnetic field in ECR system contruct resonance layer (${\omega}$=2.45GHz, $B_z$=875 Gauss) and control plasma. Plasma is almost generated at resonance layer. If the distance between substrate and resonance layer is short, uniformity of plasma is related with profile of resonance layer. Plasma have the property "Cold in Field", so directonality of magnetic field is one of the control factors of anisotropic etching. In this study, we calculate B field and flux line distribution, optimize geometry and submagnet current and improve of magnetic field directionality (99.9%) near substrate. For the purpose of calculation, vector potential A(r,z) and magnetic field B(r,z), green function and numerical integration is used. Object function for submagnet optimization is magnetic field directionality on the substrate and Powell method is used as optimization skim.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1471-1483
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• 2017

The low-frequency characteristics of four-switch three-phase (FSTP) inverter are investigated in this paper. Firstly, a general space vector pulse width modulation (SVPWM) directly involved the neutral point voltage of DC-link is proposed, where no sector identifications and trigonometric function calculations are needed. Subsequently, to suppress the DC offset in the neutral point voltage, the relationship between the neutral point voltage and the ${\beta}-axis$ component of the load current is derived, and then a new neutral point voltage control scheme is proposed where no low pass filter is adopted. Finally, the relationship between the load power factor and the maximum linear modulation index of the FSTP inverter is revealed. Since the operational region for the FSTP inverter in low frequency is reduced by the enlarged amplitude of the neutral point voltage, a linear modulation range enlargement scheme is proposed. A permanent magnet synchronous motor with preset rotary speed serves as the low-frequency load of the FSTP inverter. Experimental results verify that the new neutral point voltage control scheme is effective in the deviation suppression of the neutral point voltage, and the proposed scheme is able to provide a larger linear operational region in low frequency.

• Journal of Power Electronics
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• v.13 no.5
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• pp.806-813
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• 2013

This paper aims to compare the performance of three phase induction motor drives using Five Leg Inverter (FLI) and Three Leg Inverter (TLI) configurations. An Indirect Field Oriented Control (IFOC) method using a TLI is well established and incorporated for high performance speed drives in various industries. The FLI dual motor drive system on the other hand shows good workability in the independent control of two induction motor drives simultaneously. In this experiment, the IFOC method is utilized for both drive systems, and Space Vector Pulse Width Modulation (SVPWM) is used to generate pulses for both inverters. For the FLI, the Double Zero Sequence (DZS) Injection technique is used to generate the modulation signal. The complete experiment setup is done by using a DSpace 1103 controller board. The individual motor performances are analyzed using similar schemes, equipment setups and controller parameter values. The results show similar speed performance response capability between the single motor operation using a TLI system and the two motor operation using a FLI system based on the variable speed range either in forward or reverse operation. They also show similar load rejection abilities. However, the single motor with a TLI has a better power quality aspect such as ripple current and total harmonics distortion (THD).

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.560-564
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• 2003

This paper proposes a simple control strategy based on the discontinuous PWM(DPWM) to balance the DC-link voltage of three-level Neutral-Point-Clamped(WPC) inverters at low modulation index. New DPWM methods in multi-level inverter are also introduced. The proposed DPWM method changes the path and duration to flow the neutral point current out of or into neutral point of the DC-link and it makes the overall fluctuation of the DC-link voltage zero during a sampling time of reference voltage vector. Therefore, the voltage of the DC-link can be balanced fairly well and also the voltage ripple of the DC-link is reduced significantly. Moreover, comparing with conventional methods, the proposed strategy is very simple. The validity of the proposed DPWM method is verified by experiment

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.143-148
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• 1998

The Design criteria of the auxiliary resonant snubber inverter (ARSI) using a load-side circuit are discussed in relation to electric propulsion drives. In this regard, this paper attempts to develop a set of design criteria for the ARSI. First, the switching characteristics of IGBTs under soft-switching mainly in terms of dv/dt/, di/dt and switching losses are discussed and utilized for optimizing the selection of the resonant components in the system. After that, the proper control strategies of ARSIs are analyzed and simulated based on voltage space vector modulations. Later, the design, control and implementation of the auxiliary resonant circuit suitable for industrial products are analyzed and presented. And finally, other factors including power stage layout, packaging and the choice of current sensors are included. The detailed simulation and experimental results will be included based on a laboratory prototype. The proposed design criteria of the ARSI would help the implementation of an electric propulsion drive system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.10
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• pp.1117-1130
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• 1992

In this study, we propose a protocol for the communication between process groups required during message transfers. This is accomplished by an efficient process management of distributed systems connected by computer networks. For a single process group, a multicast protocol was proposed, which can control message flows while maintaining the order of messages sent or delivered. Through use of membership-related services, a member composing a process group may leave and join the current a membership anytime during execution. Moreover, message delivery can be delayed by using a logical vector time stamp. The functionality of the message delivery includes a virtual synchronization in response to a change in membership.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1207-1212
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• 2011

This paper presents a study on the DSP(Digital Signal Processor) controller for the PBW(power-by-wire) system using BLDC(Brushless Direct Current) servo motor pump. The PBW hydraulic actuator was realized with hydraulic pump driven by BLDC servo motor, hydraulic cylinder and controller. This PBW system needs speed control of servo motor for linear thrust action of hydraulic cylinder. This paper implements a servo controller with vector control algorithm and MIN-MAX PWM technique. As CPU of a controller, TMS320F2812 DSP was adopted because it has PWM waveform generator, A/D converter, SPI(Serial Peripheral Interface) port and many input/output port etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.998-1004
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• 2016

This paper investigates a new sensorless control appling a virtual flux oriented vector control without the line voltage sensor for the power factor correction of 3 phase PWM converter. The DC output voltage is controlled by applying the kalman filter algorithm for the virtual flux estimation and the synchronous phase is obtained by using the estimated virtual flux equation based on kalman filter. This method is used to reduce the calculation time of the system and obtain a stable control that the input current including the harmonics and the noise is improved. The proposed system implement PFC algorithm in the variable region of DC output voltage. It can obtain the unity power factor, and can precisely control the DC output voltage in the load variation and in the variable voltage range. The performance of the proposed algorithm is verified through simulation and experiment.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1527-1539
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• 2015

In this paper the hardware implementation of the direct torque control based on the fuzzy logic technique of induction motor on the Field-Programmable Gate Array (FPGA) is presented. Due to its complexity, the fuzzy logic technique implemented on a digital system like the DSP (Digital Signal Processor) and microcontroller is characterized by a calculating delay. This delay is due to the processing speed which depends on the system complexity. The limitation of these solutions is inevitable. To solve this problem, an alternative digital solution is used, based on the FPGA, which is characterized by a fast processing speed, to take the advantage of the performances of the fuzzy logic technique in spite of its complex computation. The Conventional Direct Torque Control (CDTC) of the induction machine faces problems, like the high stator flux, electromagnetic torque ripples, and stator current distortions. To overcome the CDTC problems many methods are used such as the space vector modulation which is sensitive to the parameters variations of the machine, the increase in the switches inverter number which increases the cost of the inverter, and the artificial intelligence. In this paper an intelligent technique based on the fuzzy logic is used because it is allows controlling the systems without knowing the mathematical model. Also, we use a new method based on the Xilinx system generator for the hardware implementation of Direct Torque Fuzzy Control (DTFC) on the FPGA. The simulation results of the DTFC are compared to those of the CDTC. The comparison results illustrate the reduction in the torque and stator flux ripples of the DTFC and show the Xilinx Virtex V FPGA performances in terms of execution time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.58-66
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• 2009

In this paper, vector control to applied disturbance offset feedforward loop control for changing disturbances with various mechanical parameter is suggested. The proposed system estimate load torque based on induction motor torque using minimum diemension state observer. Because speed controller using state observer is used on condition of feedforward loop fur a torque, the robust speed control system realized. In this study, the proposed paper does to heighten reliability of system by presuming and use the speed by voltage and current that is detected without speed sensor. To prove the propriety of this paper, the various simulation carried out adequacy using a Matlab Simulink, and at the same time real system is made, using a ADMC300 digital signal processor, so it is proved. As the experimental result of embodying the system, the robust system is realized.