• Journal of IKEEE
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• v.24 no.3
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• pp.877-882
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• 2020

This paper presents performance comparison study of current control methods for grid connected inverter (GCI) system. Different current control methods have been developed for GCI systems and each controller has its own advantages and limitations. Steady state and transient dynamic performance of the GCI current controllers are compared in this paper. The performance of the proposed command feedforward control (CFFC) and disturbance rejection control (DRC) is analyzed before and after application to all GCI current controllers. The proposed CFFC and DRC control algorithms is analyzed in a frequency domain and the simulation and experiment models of each GCI current control methods are developed for verification of the performance.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.91-100
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• 2007

Many manufacturing devices must execute motions as quickly as possible to achieve profitable high-volume production. Most of them have devices having flexibility and a time delay of one sampling is added to the plants when they are controlled by fast discrete controllers, which brings about non-minimum phase zeros. This paper develops a control strategy that combines feedforward and feedback control with command shaping for such devices. First, the feedback controller is designed to increase damping and eliminate steady-state error. Next, the feedforward controller is designed to speed up the transient response. Finally, an appropriate reference profile is generated using command-shaping techniques to ensure fast point-to-point motions with minimum residual vibration. The particular focus of the paper is to understand the interactions between these individual control components. The resulting control strategy is demonstrated on a model of a high-speed semiconductor manufacturing machine.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.336-340
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• 1997

This paper is a study about motor technic of motion and feedforward control in order to shape cutting control on the machine tool. The shape error caused by delay of the servo system in the direction of radius at the time of circular cutting is reduced by feedforward control, shape error generated by the position command delay is minimized by using the acceleration/deceleration time constant after the interpolation. The study was verified to optimization of motion control on experiments of a vertical machining center of the machine tool.

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.43-53
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• 2003

A modified command shaping control to reduce residual vibrations at a target position and to limit the sway angle of the payload during traveling for container crane systems is investigated. When the maneuvering time is minimized, a large transient amplitude and steady state oscillations may occur inherently. Since a large swing of the payload during the transfer is dangerous, the control objective is to transfer a payload to the desired place as quickly as possible while limiting the swing angle of the payload during the transfer. The conventional shapers have been enhanced by adding one more constraint to limit intermediate sway angles of the payload. The developed method is shown to be more effective than other conventional shapers for prevention of an excessive transient sway. Computer simulation results are provided.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.91.6-91
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• 2002

$\textbullet$ Simulation of the effect of external vibration on optical disk pickups.$\textbullet$ Vibration effect is cancelled with aceeleration feedforward. $\textbullet$ MEMS accelerometers are small enough not to require any mechanical design modification. $\textbullet$ LQR, LQG, and SMC type controllers are designed. $\textbullet$ With the feedforward, transmissibility is reduced significantly. $\textbullet$ Time domain simulation confirms the performance enhancement. $\textbullet$ The resultant system shows excellent command following characteristics as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.934-943
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• 2018

In these days, demand for agile spacecraft is gradually increasing, due to the fact that agile spacecraft can improve mission capability. In this paper, an attitude control logic based on reaction wheels that can enhance agility of spacecraft is proposed. Three methods are suggested, and all three or part of them can be integrated to the existing attitude control system. First, a feedforward/feedback controller is introduced, and its pros and cons are provided, compared to the conventional feedback controller. Second, an attitude command generation method that fully utilizes torque/momentum capacities of reaction wheels is proposed. Third, a torque (current) control mode for internal wheel control is introduced. Numerical results verify that the settling time can be significantly reduced by employing the feedforward/feedback control method, especially for large angle maneuver.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1055-1059
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• 1990

This paper proposed a predictive tracking controller for the continuous-time systems by using the receding horizon concept in the optimal tracking control. This controller is the continuous-time version of the previous RHTC (Receding Horizon Tracking Control) for the discrete-time state space models. The problems in implementing the feedforward part of this controller is discussed and a approximate method of implementing this controller is presented. This approximate method utilizes the information of the command signals on the receding horizon and has simple constant feedback and feedforward gain. To perform the offset free control, the integral action is included in the continuous time RHTC. By simulation it is shown that the proposed method gives better performance than the conventional steady state tracking control.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.70-78
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• 1999

The vector controlled induction motor(I.M) with speed sensor has been widely used for variable speed drive systems. In these application fileds, speed sensorless control are expected strongly to progress reliability, simplicity and cost performance of I.M and to expand its application part. This paper describes a novel speed sensorless control method of I.M based on feedforward quick torque response control technique. Especially, this paper aimed at the realization of sensorless control in the very low speed region, The proposed method can be formulated simply from a motor circuit equation and conducted easily by detecting primary motor currents and a voltage command at every sampling time. Throughout some results of numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter, the validity of the method was successfully confirmed.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.352-356
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• 1998

This paper is a study about Ac servo motor position and speed control characteristics which depend on feedforward control, the acceleration / deceleration time constant after the interpolation, and PI control, automatic deceleration at corner in order to shape cutting control of feed drive system of the machine tool. The shape error caused by delay of the servo system in the direction of radius at the time of circular cutting is reduced by feedforward control. The shape error generated by the position command delay is minimized by using the acceleration / deceleration time constant after the interpolation. The results were verified to optical machining center experimentation of the machine tool.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.47-50
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• 1995

This paper concerns an adaptive control scheme which is an extension of the simplified adaptive control. Originally, the SAC approach was developed based on the command generator tracker (CGT) theory for perfect model tracking. An attractive point of the SAC is that a control input can be synthesized without any prior knowledge about plant structure. However, a feedforward dynamic compensator of the CGT is removed from the basic structure of the SAC. This deletion of the compensator makes perfect model tracking difficult against even a step input. In this paper, an adaptive control system is redesigned to achieve perfect model tracking for as long as possible by reviving the dynamic compensator of the CGT. The proposed method is applied to slewing control of a flexible space structure and compared to the SAC responses.