• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.763-770
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• 2000

The speed and position information of the rotor are required in the speed control of SRM(Switched Reluctance Motors). This information is generally provided by shaft encoder or resolver. It is weak in the dusty, high temperature, and EMI environment. Consequntly, much attention has been given to SRM control for eliminationating the position and speed sensors. In this paper, a new estimation algorithm for the rotor position and speed for SRM drives is described. The algorithm is implemented by the sliding mode observer. The stability and robustness of the sliding observer for the parameter variations of the SRM are proved by variable structure control theory. Speed control of the SRM is accomplished by the estimated speed and position. Experiment results verify that the mode observer is able to estimate the speed and position well.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1644-1651
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• 2022

This paper focuses on the power-level control of nuclear power plants (NPPs) in the presence of lumped disturbances. An adaptive second-order nonsingular terminal sliding mode control (ASONTSMC) scheme is proposed by resorting to the second-order nonsingular terminal sliding mode. The pre-existing mathematical model of the nuclear reactor system is firstly described based on point-reactor kinetics equations with six delayed neutron groups. Then, a second-order sliding mode control approach is proposed by integrating a proportional-derivative sliding mode (PDSM) manifold with a nonsingular terminal sliding mode (NTSM) manifold. An adaptive mechanism is designed to estimate the unknown upper bound of a lumped uncertain term that is composed of lumped disturbances and system states real-timely. The estimated values are then added to the controller, resulting in the control system capable of compensating the adverse effects of the lumped disturbances efficiently. Since the sign function is contained in the first time derivative of the real control law, the continuous input signal is obtained after integration so that the chattering effects of the conventional sliding mode control are suppressed. The robust stability of the overall control system is demonstrated through Lyapunov stability theory. Finally, the proposed control scheme is validated through simulations and comparisons with a proportional-integral-derivative (PID) controller, a super twisting sliding mode controller (STSMC), and a disturbance observer-based adaptive sliding mode controller (DO-ASMC).

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.89-99
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• 2008

In this paper, the position tracking control problem of the servo system with nonlinear dynamic friction is issued. The nonlinear dynamic friction contains a directly immeasurable friction state variable and the uncertainty caused by incomplete parameter modeling and its variations. In order to provide the efficient solution to these control problems, we propose the composite control scheme, which consists of the robust friction state observer, the FNN approximator and the approximation error estimator with sliding mode control. In first, the sliding mode controller and the robust friction state observer is designed to estimate the unknown internal state of the LuGre friction model. Next, the FNN estimator is adopted to approximate the unknown lumped friction uncertainty. Finally, the adaptive approximation error estimator is designed to compensate the approximation error of the FNN estimator. Some simulations and experiments on the servo system assembled with ball-screw and DC servo motor are presented. Results show the remarkable performance of the proposed control scheme. The robust friction state observer can successfully identify immeasurable friction state and the FNN estimator and adaptive approximation error estimator give the robustness to the proposed control scheme against the uncertainty of the friction parameters.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.74-76
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• 2009

In this paper, search method and sliding mode observer are developed for efficiency optimization of induction motor. The proposed control scheme consists of efficiency controller and adaptive backstepping controller. A search controller for which information of input of fuzzy controller is included in efficiency controller that uses a direct vector controlled induction motor. The search controller is based on the "Rosenbrock" method and finds the flux level at the minimum input power of induction motor. Once this optimal flux level has been determined, this information is utilized to update the rule base of a fuzzy controller A sliding mode observer is designed to estimate rotor flux and an adaptive backstepping controller is also used to compensate for mechanical uncertainties in the speed control of induction motor. Simulation results are presented to validate the proposed controller.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.420-425
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• 1996

In this paper a robust speed controller for an induction motor is proposed. The speed controller consists or a fuzzy sliding adaptive controller(FSAC) and a sliding mode torque observer(SMTO). FSAC removes the problem or oscillations caused by discontinuous inputs of the sliding mode controller. The controller also provides robust characteristics against parameter and sampling time variations. Although, however, the performance of FSAC is better than PI controller and fuzzy controller in robustness, it generates the problem of slow response time. To alleviate this problem, a compensator, which performs feedforward control using torque signals produced by SMTO, is added. The simulation and hardware implementation results show that the proposed system is robust to the load disturbance, parameter variations, and measurement noises.

• Journal of Power Electronics
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• v.14 no.1
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• pp.125-134
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• 2014

This paper presents a robust and speed-sensorless stator flux estimation for induction motor direct torque control. The proposed observer is based on sliding mode approach. Stator electrical equations are used in the rotor orientation reference frame to eliminate the observer dependence on rotor speed. Lyapunov's concept for systems stability is adopted to confine the observer gain. Furthermore, the sensitivity of the observer to parameter mismatch is recovered with an adaptation technique. The nonlinearities of the pulse width modulation voltage source inverter are estimated and compensated to enhance stability at low speeds. Therefore, a new method based on the model reference adaptive system is proposed. Simulation and experimental results are shown to verify the feasibility and effectiveness of the proposed algorithms.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.3
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• pp.778-784
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• 2017

This paper proposes a sensorless speed control of a permanent magnet synchronous motor (PMSM) based on an adaptive sliding mode observer (SMO) for electric propulsion system of small ships. An adaptive observer gain is proposed based on the Lyapunov's stability criterion to reduce the chattering problem at any speed operation instead of the constant gain observer. Furthermore, a cascade low-pass filter with variable cut-off frequency is suggested to strengthen the filtering capability of the observer. The experimental results from a 1.5 kW PMSM drive are provided to verify the effectiveness of the proposed adaptive SMO. The result shows that the proposed method gives good speed control performances even when the PMSM operates at 0.5% from its rated speed value.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.3
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• pp.145-153
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• 2004

A nonlinear adaptive speed observer is designed for the sensorless control of induction motors. In order to design the speed observer, the measurements of the stator currents and the estimates of the rotor fluxes are used. The sliding mode cascade observer is designed to estimate the time derivatives of the stator currents. The open-loop observer is designed to estimate the rotor fluxes and its time derivatives using the stator current derivatives. The adaptive observer is also designed to estimate the rotor resistance. Sequentially, the rotor speed is calculated using these estimated values. It is shown that the estimation errors of the corresponding states and the parameters converge to the specified residual set. It is also shown that the speed controller using these estimates is performed well. The simulation examples are represented to investigate the validity of the proposed observers for the sensorless control of induction motors.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.9
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• pp.822-826
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• 2013

In this paper, we propose an AFDO (Adaptive Fault Diagnosis Observer) and a fault tolerant controller for a class of nonlinear continuous-time system under the nonlinear abrupt actuator faults. Together with its estimation laws, the AFDO which estimates that the actuator faults is designed by using the Lyapunov analysis. Then, based on the designed AFDO, an adaptive sliding mode controller is proposed as the fault tolerant controller. Using Lyapunov stability analysis, we also prove the uniform boundedness of the state, the output and the fault estimation errors, and the asymptotic stability of the tracking error under the nonlinear time-varying faults. Finally, we illustrate the effectiveness of the proposed diagnosis method and the control scheme thorough computer simulations.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2393-2405
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• 2015

This paper considers a decentralized multiple faults detection and isolation (FDI) scheme for reconfigurable manipulators. Inspired by their modularization property, a global sliding mode (GSM) based stable adaptive fuzzy decentralized controller is investigated for the system in fault free, while for the system suffering from multiple faults (actuator fault and sensor fault), the decentralized sliding mode observer (DSMO) is employed to detect their occurrence. Hereafter, the time and location of faults can be determined by a fault isolation scheme via a bank of DSMOs. Finally, the effectiveness of the proposed schemes in controlling, detecting and isolating faults is illustrated by the simulations of two 3-DOF reconfigurable manipulators with different configurations successfully.