• Journal of Power Electronics
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• v.1 no.2
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• pp.117-126
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• 2001

A synchronous motor(SM) with q-axis special field winding of which the q-axis field-current compensates and cancels armature reaction can be driven at unity power factor under the conditions of transient state as well as steady state. The motor operates in high efficiency in all conditions. However, in order to obtain maximum performance of the motor, it is required that the time constant of armature circuit corresponds to that of q-axis field circuit. Inverse LQ(ILQ) design method on a basis of the pole assignment is suitable for this problem:(1) The time constants of the output responses can be designed for desired specifications, (2) Relations between feedback gains and response of closed loop system are very clear and (3) Optimal solutions can be given by simple procedure of ILQ method without solving the Ricaati's equation, compared to the usual LQ design method. Accordingly, the ILQ method can make the responses of armature current and q-axis field-current correspond. In this paper, it is proved by numerical simulations and experiments that the ILQ method is very effective for optimal regulator design of this plant and realizes a high-performance motor with unity power factor and high efficiency.

• Journal of Power Electronics
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• v.14 no.1
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• pp.92-104
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• 2014

To insure stable operation and eliminate twice torque ripple, a topology for a six phase permanent magnet synchronous generator (SP-PMSG) with a neutral point connected together was analyzed in this paper. By adopting an extended transformation matrix, the mathematic model of the space vector control was established. The voltage and torque equations were deduced while considering the third harmonic flux and inductance. In addition, the suppression third harmonic method and the closed loop control strategy were proposed. A comparison analysis indicates that the cooper loss minimum method and the current magnitude minimum method can meet different application requirements. The voltage compensation amount for each of the methods was deduced which also takes into account the third harmonic effect. A simulation and experimental result comparison validates the consistency through theoretical derivation. It can be seen that all of the two control strategies can meet the requirements of post-fault.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.417-425
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• 2006

This paper presents a new speed sensorless vector control scheme of Spindle Induction Motors(SIM) which can be successfully applied to at any speed including even zero speed. The proposed sensorless vector control of SIM uses rotor flux estimator with a variable bandwidth. This approach is based on the Closed-Loop Rotor Flux Observer(CLRFO) which includes a variable bandwidth of the PI controller. For low speed operation, the bandwidth of CLRFO has a variable bandwidth structure according to the estimated rotor velocity. The experimental results show the satisfactory operation of the proposed sensorless algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.7
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• pp.646-654
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• 2010

This paper describes an integrated chassis control for a maneuverability, a lateral stability and a rollover prevention of a vehicle by the using of the ESC and AFS. The integrated chassis control system consists of a supervisor, control algorithms and a coordinator. From the measured and estimation signals, the supervisor determines the vehicle driving situation about the lateral stability and rollover prevention. The control algorithms determine a desired yaw moment for lateral stability and a desired longitudinal force for the rollover prevention. In order to apply the control inputs, the coordinator determines a brake and active front steering inputs optimally based on the current status of the subject vehicle. To improve the reliability and to reduce the operating load of the proposed control algorithms, a multi-core ECU platform is used in this system. For the evaluation of this system, a closed loop simulations with driver-vehicle-controller system were conducted to investigate the performance of the proposed control strategy.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.648-658
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• 2018

Regarding the fact that wind power forecast accuracy is gradually improved as time is approaching, this paper proposes a two-stage rolling dispatch approach based on model predictive control (MPC), which contains an intra-day rolling optimal scheme and a real-time rolling base point tracing scheme. The scheduled output of the intra-day rolling scheme is set as the reference output, and the real-time rolling scheme is based on MPC which includes the leading rolling optimization and lagging feedback correction strategy. On the basis of the latest measured thermal unit output feedback, the closed-loop optimization is formed to correct the power deviation timely, making the unit output smoother, thus reducing the costs of power adjustment and promoting wind power accommodation. We adopt chance constraint to describe forecasts uncertainty. Then for reflecting the increasing prediction precision as well as the power dispatcher's rising expected satisfaction degree with reliable system operation, we set the confidence level of reserve constraints at different timescales as the incremental vector. The expectation of up/down reserve shortage is proposed to assess the adequacy of the upward/downward reserve. The studies executed on the modified IEEE RTS system demonstrate the effectiveness of the proposed approach.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1356-1357
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• 2011

Interior permanent magnet synchronous motor(IPMSM) adjustable speed drives offer significant advantages over induction motor drives in a wide variety of industrial applications such as high power density, high efficiency, improved dynamic performance and reliability. This paper proposes on-line efficiency optimization of IPMSM drive using fuzzy logic control(FLC) and the loss minimization method. In order to optimize the efficiency the loss minimization algorithm is developed based on motor model and operating condition. The d-axis armature current is utilized to minimize the losses of the IPMSM in a closed loop vector control environment. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM. The optimal current can be decided according to the operating speed and the load conditions. The proposed control algorithm is applied to IPMSM drive system and the operating characteristics controlled by the loss minimization method and FLC control are examined in detail.

• Journal of Drive and Control
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• v.19 no.1
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• pp.51-61
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• 2022

This paper presents a model-free system based on a framework of a backstepping sliding mode control (BSMC) with a radial basis function neural network (RBFNN) and adaptive mechanism for electro-hydraulic systems (EHSs). First, an EHS mathematical model was dedicatedly derived to understand the system behavior. Based on the system structure, BSMC was employed to satisfy the output performance. Due to the highly nonlinear characteristics and the presence of parametric uncertainties, a model-free approximator based on an RBFNN was developed to compensate for the EHS dynamics, thus addressing the difficulty in the requirement of system information. Adaptive laws based on the actor-critic neural network (ACNN) were implemented to suppress the existing error in the approximation and satisfy system qualification. The stability of the closed-loop system was theoretically proven by the Lyapunov function. To evaluate the effectiveness of the proposed algorithm, proportional-integrated-derivative (PID) and improved PID with ACNN (ACPID), which are considered two complete model-free methods, and adaptive backstepping sliding mode control, considered an ideal model-based method with the same adaptive laws, were used as two benchmark control strategies in a comparative simulation. The simulated results validated the superiority of the proposed algorithm in achieving nearly the same performance as the ideal adaptive BSMC.

• Korean Journal of Optics and Photonics
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• v.32 no.1
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• pp.1-8
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• 2021

We have studied a tiled-aperture coherent-beam-combining system based on constructive interference, as a way to overcome the power limitation of a single laser. A 1-watt-level, 3-channel coherent fiber laser and a 3-channel fiber array of triangular tiling with tip-tilt function were developed. A monitoring system, phase controller, and 3-channel phase modulator formed a closed-loop control system, and the SPGD algorithm was applied. Eventually, phase-locking with a rate of 5-67 kHz and peak-intensity efficiency comparable to the ideal case of 53.3% was successfully realized. We were able to develop the essential elements for a tiled-aperture coherent-beam-combining system that had the potential for highest output power without any beam-combining components, and a multichannel coherent-beam-combining system with higher output power and high speed is anticipated in the future.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.299-306
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• 2010

This paper proposes a new doubly-fed induction generator (DFIG) system using a matrix converter controlled by direct duty ratio pulse-width modulation (DDPWM) scheme. DDPWM is a recently proposed carrier based modulation strategy for matrix converters which employs a triangular carrier and voltage references in a voltage source inverter. By using DDPWM, the matrix converter can directly and effectively generate rotor voltages following the voltage references within the closed control loop. The operation of the proposed DFIG system was verified through computer simulation and experimental works with a hardware simulator of a wind power turbine, which was built using a motor-generator set with vector drive. The simulation and experimental results confirm that a matrix converter with a DDPWM modulation scheme can be effectively applied for a DFIG wind power system.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.2
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• pp.106-115
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• 2013

LED lighting control system using unidirectional DMX512 (digital multiplex with 512 pieces of information)) protocol has been the most popular. Nowadays, the user's consumption has been upgrading to the more intelligent system but the upgrading process does not affect the existing infrastructure. There were many researches use the additional communication for the feedback communication way such as WiFi, Controller Area Network (CAN), Power Line Communication (PLC), etc but all researches had inherent disadvantages that created the independent feedback with the existing DMX512 system. Our paper represents the novel method that uses the remote device management (RDM) protocol to associate the additional feedback with existent DMX512 infrastructure in the one system. The data in DMX512 frame sending to the DMX512 client is split and repacked to become the RDM packet. This RDM packet is transferred to the RDM monitor console and the response RDM packet is converted to the DMX512 frame for control DMX512 client devices. This is the closed loop control model which uses the bidirectional convertibility between RDM packet and DMX512 frame. The proposed method not only upgrades the feedback control function for the old DMX512 system without changing the existent infrastructure, but also solves compatible problems between new RDM devices and old DMX512 devices and gives the low cost solution for extending DMX512 universe.