• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.687-690
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• 2004

Many studies have been performed for the elimination of speed and position sensors which require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. This paper investigates an improved sliding mode observer for the sensorless speed control of a permanent magnet synchronous motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-response control. The proposed algorithm is verified through the simulation and experimentation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.211-218
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• 2021

This paper addressed the problems of controlling the coupled pitch-roll motions in a marine vessel exposed to the regular waves in the longitudinal and transversal directions. Stabilization of the pitch and roll motions can be regarded as the essential task to ensure the safety of a ship's navigation. One of the important features in the pitch-roll motions is the resonance phenomena, which result in unexpected large responses in terms of pitch and roll modes in some specific conditions. Besides, owing to its inherent characteristics of coupled combination and nonlinearity of restoring terms, the vessel shows various dynamical behaviors according to the system parameters, especially in the pitch responses. Above all, it can be seen that suppression of pitch rate remains the most significant challenge to overcome for ship maneuvering safety studies. To secure the stable upright condition, a quasi-sliding mode control scheme is employed to reduce the undesirable pitch and roll responses as well as chattering elimination. The Lyapunov theory is adopted to guarantee the closed stability of the pitch-roll system. Numerical simulations demonstrate the effectiveness of the control scheme. Finally, the control goals of state convergences and chattering reduction are effectively realized through the proposed control synthesis.

• Journal of Power Electronics
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• v.17 no.4
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• pp.991-1003
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• 2017

The conventional sliding mode control (CSMC) has a number of problems. It may cause dc output voltage ripple and it cannot guarantee the robustness of the whole system for a matrix rectifier (MR). Furthermore, the existence of a filter can decrease the input power factor (IPF). Therefore, a novel global sliding mode control (GSMC) based on a hyperbolic tangent function with IPF compensation for MRs is proposed in this paper. Firstly, due to the reachability and existence of the sliding mode, the condition of the matrix rectifier's robustness and chattering elimination is derived. Secondly, a global switching function is designed and the determination of the transient operation status is given. Then a SMC compensation strategy based on a DQ transformation model is applied to compensate the decreasing IPF. Finally, simulations and experiments are carried out to verify the correctness and effectiveness of the control algorithm. The obtained results show that compared with CSMC, applying the proposed GSMC based on a hyperbolic tangent function for matrix rectifiers can achieve a ripple-free output voltage with a unity IPF. In addition, the rectifier has an excellent robust performance at all times.