• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.819-822
• /
• 1998

A new active power filter (APF) circuit with a current compesation estimation method is proposed. The current compensation estimation method replaces a current sensor with an estimating circuit and therefore reduces the implementation cost In addition, a simple control scheme, based on the energy balance concept, is adopted to control the voltage of a DC capacitor. Therefore energy change in the DC capacitor can be compensanted in the next cycle. Since a sampling technique is used, a larger DC capacitor voltage ripple can be permissible and a relatively smaller DC capacitor can be used. The proposed method has advantages of the reduction of one current sensor, low implementation cost, and fast transient responses. The theoretical analysis and simulation results are given. The proposed control method is successfully verified by computer simulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.30 no.4
• /
• pp.329-340
• /
• 1994

This paper presents a dynamic compensation methodology for robust trajectory tracking control of uncertain robot manipulators. To improve tracking performance of the system, a full model-based feedforward compensation with continuous VS-type robust control is developed in this paper(i.e,. robust decentralized adaptive control scheme). Since possible bounds of uncertainties are unknown, the adaptive bounds of the robust control is used to directly estimate the uncertainty bounds(instead of estimating manipulator parameters as in centralized adaptive control0. The global stability and robustness issues of the proposed control algorithm have been investigated extensively and rigorously via a Lyapunov method. The presented control algorithm guarantees that all system responses are uniformly ultimately bounded. Thus, it is shown that the control system is evaluated to be highly robust with respect to significant uncertainties.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.1
• /
• pp.169-175
• /
• 2006

This paper describes how an Artificial Neural Network(ANN) can be employed to improve a speed estimation in a vector controlled induction motor drive. The system uses the ANN to estimate changes in the motor resistance, which enable the sensorless speed control method to work more accurately. Flux Observer is used for speed estimation in this system. Obviously the accuracy of the speed control of motor is dependent upon how well the parameters of the induction machine are known. These parameters vary with the operating conditions of the motor; both stator resistance(Rs) and rotor resistance(Rr) change with temperature, while the stator leakage inductance varies with load. This paper proposes a parameter compensation technique using artificial neural network for accurate speed estimation of induction motor and simulation results confirm the validity of the proposed scheme.

• Journal of Advanced Marine Engineering and Technology
• /
• v.27 no.4
• /
• pp.503-510
• /
• 2003

A new method of induction motor drive, which requires neither shaft encoder nor speed estimator, is presented. The proposed scheme is based on decreasing current gap between a numerical model and an actual motor. By supplying the identical instantaneous voltage to both model and motor in the direction of reducing the current difference. the rotor approaches to the model speed. that is. reference value. The indirect field orientation algorithm is employed for tracking the model currents. The performance of induction motor drives without speed sensor is generally characteristic of poorness at very low speed. However, in this system, it is possible to obtain good speed response in the extreme low speed range.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.4 s.175
• /
• pp.866-873
• /
• 2000

Sliding mode control(SMC) incorporated with perturbation compensation is developed here to reduce the low-frequency tracking error in the presence of wide-band frequency perturbations for a nonlinear dynamic system. The control scheme is designed for estimation of low frequency perturbations with employment of the Time Delay Control and low-pass filter. It is shown that the SMC with perturbation compensation is far superior to the conventional SMC in tracking control of the dynamic systems under model uncertainties and external disturbance conditions.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.1
• /
• pp.94-100
• /
• 2008

This paper presents a new control method of single-phase active power filter (APF) for the compensation of harmonic current components in nonlinear loads. To facilitate the possibility of complex calculation for harmonic current detection of the single phase, a single-phase system that has two phases was constructed by including an imaginary second-phase giving time delay to the load current. The imaginary phase, which lagged the load current T/4 (Here T is the fundamental cycle) is used in the conventional method. But in this proposed method, the new signal as the second phase is delayed by the filter. Because this control method is applied to a single-phase system, an instantaneous calculation was developed by using the rotating reference frames synchronized to source-frequency rather than by applying instantaneous reactive power theory that uses the conventional fixed reference frames. The control scheme of single-phase APF for the current source with R-L loads is applied to a laboratory prototype to verify the proposed control method.

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.49-52
• /
• 1988

This paper deal with the robust high gain controller design technique by inner-loop feedback, output feedback, feedforward compensation, and presented the algorithm to be required the determination of gain matrix. Using this control scheme, simulation results have bean tested for the linearized model of the aircraft.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.472-473
• /
• 2008

This paper presents a charge pump used in frequency synthesizer for PHS application. The up/down current mismatch of charge pump has a critical effect on the phase noise and spur performance in frequency synthesizer. Therefore, the mismatch compensation scheme is proposed in this paper. And, the measurement results show that the mismatch can be reduced below 5 %.

• Speech Sciences
• /
• v.13 no.1
• /
• pp.117-128
• /
• 2006

The two-channel Generalized Sidelobe Canceller (GSC) scheme suffers from the presence of leakage signal in the reference channel. The leakage signal is caused by the dissimilar impulse responses between microphones, and different paths from speech source to microphones. Such leakage is detrimental to speech enhancement of the GSC since the desired reference signal becomes corrupted. In order to suppress the signal leakage, two matrix injection methods are proposed. In the first method, a simple gain compensation matrix is used. In the second, a projection matrix for reducing the error between the actual and the ideal primary and reference signals, is used. This paper describes the performance degradation resulting from leakage, and proposes effective methods to resolve the problem. Representative experiments were conducted to demonstrate the effectiveness of the proposed methods on recorded speech and noise in an actual automobile environment.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.102.4-102
• /
• 2002

A deadzone compensator is designed for a positioning system using fuzzy logic. The classification property of fuzzy logic systems make them a natural candidate for the rejection of errors induced by the deadzone, which has regions in which it behaves differently. A tuning algorithm is given for the fuzzy logic parameters, so that the deadzone compensation scheme becomes adaptive, guaranteeing small tracking errors and bounded parameter estimates, formal nonlinear stability proofs are given to show that the tracking error is small. The fuzzy logic deadzone compensator is implemented on a positioning system to show its efficacy. 1. Deadzone Compansation 2. XY positioning table 3. Fuzzy Logic 4. Actuator nonlinearity