• Proceedings of the KIEE Conference
• /
• 1998.07a
• /
• pp.18-21
• /
• 1998

A stabilization scheme of a missile actuator using fuzzy controller is proposed. A variable-reluctance stepping motor adopted as a actuator is critically restricted useful operation since pronounced oscillatory behaviour at a certain input frequencies. The previous stabilization scheme. which employs frequency modulation, of the clock-pulse source using derived from the modulation envelope of the total intake current is modified using fuzzy control. The proposed scheme has apparent advantage, particularly in size, mass and flexibility.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.181-185
• /
• 2000

To get high efficiency in variable speed control of induction motor it is required that the vector control should be separated from flux components current and torque component current. In this paper the vector control is modeled by the estimation of the stator flex. Representing induction motor speed controller as a digital system with he use of he 32bit DSP improves the motor control performance The IGBT is used as the switching device and the validity of the proposed vector control is proved through voltage current wave and the characteristics of the velocity response as the drive circuit being simplified

• Journal of Biosystems Engineering
• /
• v.31 no.3 s.116
• /
• pp.203-208
• /
• 2006

This study was conducted to improve the control performance of a current variable-rate controller for granular fertilizers. Simulation model was developed. Optimized proportional, integral and derivative gains were determined by simulation model using 2nd order PID gain learning algorithm, and these control gains were evaluated through the field tests. Important results of this study are as follows; 1. Principles of pre-existing variable-rate application of granular fertilizers were investigated. 2. Simulation model of a PID controller that could simulate the control system was developed by using Matlab/Simulink program. The program was to determine PID control coefficients through the simulation model and 2nd order PID gain learning algorithm. 3. PID control coefficients obtained from the simulation were applied to the developed model. When the step input was given, Maximum overshoot were 1.96%, rise time were 0.05 sec, settling time were 0.06 sec and steady state error were 0.21 % respectively. 4. The simulation model was verified through field tests. The errors of maximum overshoot were 10%, rise time were 0.11 sec, settling time were 0.40 sec and steady state error were 8% because of loads and noises. Rise time was decreased to one third of that of the pre-existing system. 5. If the speed of a fertilizing machine is $0.3{\sim}0.6\;m/s$ and the maximum rotation speed of a discharging roller is 64 rpm, rise time would be 0.26 sec and fertilizing machine would cover the distance of $0.07{\sim}0.15\;m$ with settling time of 0.4 sec, fertilizing machine would cover the distance of $0.12{\sim}0.24\;m$.

• Journal of Power Electronics
• /
• v.16 no.3
• /
• pp.1176-1189
• /
• 2016

In this paper, a novel quasi-direct power control (Q-DPC) scheme based on a resonant frequency adaptive proportional-resonant (PR) current controller with a variable frequency resonant phase locked loop (RPLL) is proposed, which can achieve a fast power response with a unity power factor. It can also adapt to variations of the generator frequency in T-type Three-level shaft synchronous generator (SSG) converters. The PR controller under the static α-β frame is designed to track ac signals and to avert the strong cross coupling under the rotating d-q frame. The fundamental frequency can be precisely acquired by a RPLL from the generator terminal voltage which is distorted by harmonics. Thus, the resonant frequency of the PR controller can be confirmed exactly with optimized performance. Based on an instantaneous power balance, the load power feed-forward is added to the power command to improve the anti-disturbance performance of the dc-link. Simulations based on MATLAB/Simulink and experimental results obtained from a 75kW prototype validate the correctness and effectiveness of the proposed control scheme.

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.9
• /
• pp.692-699
• /
• 2003

A novel rotor speed estimation method using Model Reference Adaptive Control(MRAC) is proposed to improve the performance of a sensorless vector controller. In the proposed mettled, the stator current is used as the model variable for estimating the speed. In conventional MRAC methods, the relation between the two model errors and the speed estmation error is unclear. Yet, in the proposed method, the stator current error is represented as a function of the first degree for the error value in the speed estimation. Therefore, the proposed method can produce a fast speed estimation and is robust to the parameters error In addition, the proposed method of offers a considerable improvement in the performance of a sensorless vector controller at a low speed. The superiority of the proposed method is verified by simulation and experiment in a low speed region and at a zero-speed.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.270-272
• /
• 1994

A new current control technique for inverter-fed vector controlled induction motor drives is presented. Using a integral variable structure control(IVSC) approach, the current controller is designed in the stationary rotating reference frame. The chattering reduction technique is also considered by the full state flux observer. By employing the proposed control scheme, a good control performance is achieved in the transient and steady state. The effectiveness of the proposed scheme is demonstrated through the comparative simulations.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.441-443
• /
• 2007

In this paper, The authors design the current controller which independently control the d, q axis current transformed by the synchronously rotating d, q axis and a Space Vector Pulse Width Modulation(SVPWM) to steadily control the output DC-Link voltage against the variable load of the three phase PWM converter. Also, This study improves the high power factor, stability, and rapid response by the phase angle control using the digital Phase Locked Loop(PLL).

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.1
• /
• pp.111-119
• /
• 2013

This paper present stabilization control of fixed speed wind generator by using variable speed permanent magnet wind generator in a wind farm connected with multi-machine power system. A novel direct-current based d-q vector control technique of back to back converter integrated with Fuzzy Logic Controller for optimal control configuration is proposed, in which both active and reactive powers delivered to a power grid system are controlled effectively. Simulation analyses have been performed using PSCAD/EMTDC. Simulation results show that the proposed control scheme is very effective to enhance the voltage stability of the wind farm during fault condition.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.11
• /
• pp.563-567
• /
• 2001

ln this paper, the designed DVSC(Discrete Variable Structure Controller) is applied to the robust control of voltage controlled APF(Active Power Filter). The voltage controlled APF has good characteristics of reducing harmonic current and harmonic voltage simultaneously. However, voltage controlled APF with large capacitor has slow dynamic response. For improving the dynamics and robustness against to disturbances, DVSC is adopted. According to the results of experiment and simulation, it is proved that the proposed system has the performance of improving dynamic response and robustness.

• Journal of the Korean Society for Railway
• /
• v.13 no.2
• /
• pp.166-172
• /
• 2010

Currently, vector control is used for speed control of trains because induction motor has high performance is installed in Electric railroad systems. Also, control of the induction motor is possible through various methods by developing inverters and control theory. Presently, rolling stocks which use the induction motor are possible to brake trains by using AC motor. Therefore model of motor block and induction motor is needed to adapt various methods. There is Variable Voltage Variable Frequency (VVVF) as the control method of the induction motor. The torque and speed is controlled in the VVVF. The propulsion system model in the electric railroad has many sub-systems. So, the analysis of performance of the speed control is very complex. In this paper, simulation models are suggested by using Matlab/Simulink in the speed control characteristic. On the basis of the simulation models, the response to disturbance input is analyzed about the load. Also, the current, speed and flux control model are proposed to analyze the speed control characteristic in the train propulsion system.