• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.205-209
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• 1999

This paper proposes a variable structure position controller for an induction motor(IM) which uses a reaching law and an integral compensating nonlinear switching function. With the reaching law, reaching mode can be established quantitatively during transient state so that dynamic control performance is improved. With the integral compensating nonlinear switching function, both very low overshoot and high steady state control accuracy can be obtained by compensating the states chattering problem due to the unmodelled dynamics of inverter and feedback sensors. For experiment a digital servo driver which consists of a DSP and an IPM inverter was developed. With the various experimental results, IM position control performance was verified.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2173-2175
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• 2003

This paper presents a cruise control system design using variable structure control (AVCS) is an important part of the intelligent vehicle and highway systems (IVHS). A vehicle desired acceleration profile has been designed based on the vehicle speed and distance control algorithm. Cruise control system has been designed using VSC theory for which we propose a moving switching surface(MSS). It has been shown that the proposed control system can provide satisfactory performance. Simulation results are given to show the effectiveness of this controller.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.873-876
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• 1993

A scheme of IEVSC(Integral Error Variable Structure Controller) is proposed for the DC servo systems with the disturbances which does not satisfy the matching condition. The structure of IEVSC is composed of state observer, VSC, and servo compensator which is designed for the output variable enhances the robustness against all type of disturbances. The performances of proposed IEVSC are verified through simulations for the DC servo motor.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1041-1043
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• 1993

A robust position control scheme for a Brushless Direct Drive Motor(BLDDM) is presented. To obtain the robustness under the load variation, a Variable Structure Controller(VSC) is used. However, the VSC has a chattering problem and require the full state informations. To overcome this problem, in this paper, the sliding mode observer is used for compensating the load disturbance and estimating the motor velocity. As a result, the VSC for a BLDDM posision control is designed by using only position measurment and the chattering problem is greatly reduced. To show the validaty of the proposed scheme, the simulation study is carried out.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.57-60
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• 2001

This paper presents a new method for removing reaching phase in variable structure control systems using Bell type switching function. By proposed method, during the entire control process reaching phase is removed. For effective speed control of trapezoidal type brushless DC motor, a time varying switching function based speed controller is developed as illustration.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.176-178
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• 2003

This paper presents a new velocity estimation strategy of a non-salient permanent magnet synchronous motor(PMSM) drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system which has the information of rotor position error. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error to aero. For zero and low speed operation, the PI gains of rotor position tracking controller have a variable structure. The PI tuning formulas are derived by analyzing this control system using the frequency domain specifications such as phase margin and bandwidth assignment.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.240-245
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• 1998

This paper presents an improved sliding mode controller design for induction motor. In place of the discontinuous control inputs, continuous inputs are proposed in order to remove the undesirable chattering phenomena, which represent major drawbacks of the sliding mode controller. The design strategy is illustrated with a microprocessor based implementation for the velocity control of an induction motor. An induction motor is operated under sling mode control such that the motor angular velocity follows a predetermined trajectory. The experimental results confirm the validity of the proposed method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.125-130
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• 1999

In this paper, it is presented a new technique to the design and real-time implementation of fuzzy control system based-on digital signal processors in order to improve the precision and robustness for system of industrial robot. Fuzzy control has emerged as one of the most active and fruitful areas for research in the applications of fuzzy set theory, especially in the real of industrial processes. In this thesis, a self-organizing fuzzy controller for the industrial robot manipulator with a actuator located at the base is studied. A fuzzy logic composed of linguistic conditional statements is employed by defining the relations of input-output variable of the controller, In the synthesis of a FLC, one of the most difficult problems is the determination of linguistic control rules from the human operators. To overcome this difficult, SOFC is proposed for a hierarchical control structure consisting of basic level and high level that modify control rules.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.10a
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• pp.209-215
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• 1998

This paper deals with stand-alone Photovoltaic system(SPVS) with charge and discharge controller. Main power source of SPVS are generally solar cell and battery. therefore SPVS can be classified into variable types in accordance with connection type between battery and solar cell. Mainly used one of them is direct connection type which has advantages such as simple structure and simple controller. However most big drawback of this system is energy loss by voltage disharmony between solar cell and battery. Therefore SPVS with charge and discharge controller which can operate solar cell at maximum power point is designed and analyzed by simulation in this paper.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.822-825
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• 1993

A fuzzy logic controller derived from the variable structure control (VSC) theory is designed. Unlike the conventional design of the fuzzy controller, we do not fuzzify the error and the rate of error, but fuzzify the sliding surface. After the fuzzy sliding surface is introduced, the fuzzy rules are defined based on the sliding control theory. It will be shown this sliding mode fuzzy controller is a kind of VSC that introduces the boundary layer in the switching surface and that the control input is continuously approximated in the layer. As a result we can guarantee the stability and the robustness by the help of VSC, which were difficult to insure in the past fuzzy controllers. Simulation results for the inverted pendulum will show the validity.