• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.215-225
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• 2011

In this paper, a buck DC-DC bridge converter is used as a power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of the PFC converter is a diode bridge rectifier (DBR) fed from single phase AC mains. The PMBLDCM is used to drive the compressor of an air conditioner through a three-phase voltage source inverter (VSI) fed from a variable voltage DC link. The speed of the air conditioner is controlled to conserve energy using a new concept of voltage control at a DC link proportional to the desired speed of the PMBLDC motor. Therefore, VSI operates only as an electronic commutator of the PMBLDCM. The current of the PMBLDCM is controlled by setting the reference voltage at the DC link as a ramp. The proposed PMBLDCM drive with voltage control-based PFC converter was designed and modeled. The performance is simulated in Matlab-Simulink environment for an air conditioner compressor load driven through a 3.75 kW, 1500 rpm PMBLDC motor. To validate the effectiveness of the proposed speed control scheme, the evaluation results demonstrate improved efficiency of the complete drive with the PFC feature in a wide range of speed and input AC voltage.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.637-644
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• 2006

The detection of engine misfire events is one of major concerns in engine control due to its negative effect on air pollution and engine performance. In this paper, a misfire detection system based on crankshaft angular speed fluctuation is developed. Synthetic variable method is adopted for the preprocessing of crankshaft angular speed. This method successfully estimates the work output of each cylinder by finding the effect of combustion energy on the crankshaft rotational speed or acceleration after virtually removing the effect of the internal inertia forces from the measured crankshaft speed signals. The detection system is developed using neural network with the revised synthetic angular acceleration as input which is derived from the preprocessing. Mathematical simulation is carried out for developing and verifying the misfire detection system. Finally, the reliability of the developed system is validated through an experiment.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.540-543
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• 1999

This paper describes a speed sensorless algorithm for vector control system with compensated stator resistance and rotor time constant of induction motor using a model reference adaptive system(MRAS). The system are composed of two MRAC, one is a rotor speed estimation and a stator resistor identification by back-EMF observer, other is used to identify rotor time constant by magnetizing current observer, so that the estimation can be cover a very low speed range with a robust control. The suggest control strategy and estimation method have been validated by simulation study. In the simulation using Matlab/Simulik, the proposed speed sensorless vector control system are shown to operate very well in spite of variable rotor time constant and load fluctuation.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.23-35
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• 1998

A new instantaneous torque control is presented for a high performance control of a permanent magnet(PM) synchronous motor. In order to deal with the torque pulsating problem of a PM synchronous motor in a low speed region, new torque estimation and cotrol techniques are proposed. The linkage flux of a PM synchronous motor is estimated using a model reference adaptive system technique and the torque is instantaneously controlled by the proposed torque controller combining an integral variable structure control with a space vector PWM. The proposed control provides the advantage of reducing the torque pulsation caused by the non-sinusoidal flux distribution. This control strategy is applied to the high torque PM synchronous motor drive system for direct drive applications and implemented by using a software of the DSP TMS320C30. The simulations and experiments are carried out for this system and the results well demonstrate the effectiveness of proposed control.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1165-1168
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• 2002

This paper presents a neural network based self-tuning fuzzy PID control scheme with variable learning rate for sensorless vector controlled induction motor drives. MRAS(Model Reference Adaptive System) is used for rotor speed estimation. When induction motor is continuously used long time. its electrical and mechanical parameters will change, which degrade the performance of PID controller considerably. This paper re-analyzes the fuzzy controller as conventional PID controller structure, introduces a single neuron with a back-propagation learning algorithm to tune the control parameters, and proposes a variable learning rate to improve the control performance. The proposed scheme is simple in structure and computational burden is small. The simulation using Matlab/Simulink and the experiment using DS1102 board show the robustness of the proposed controller to parameter variations.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.49-56
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• 2008

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is a combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. In this paper the effect of transformer is studied. Multiple closed loop controllers with displacement feedback of variable pump/motor, speed feedback and position feedback of cylinder are used. The efficiency and energy consumption when cylinder is driven up and down is calculated by simulation. Simulation results show that considerable energy saving is achieved by choosing load ratio, circuit type and supply pressure.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.719-727
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• 1999

A robust position control method of the BLDC motor using a new sliding mode control strategy is presented. The main property of variable structure system(VSS) is that the system response is robust and insensitive to parameter variations and external disturbances in the sliding mode. When using the conventional VSS, generally the reaching phase problem occurs, which cause the system response to be sensitive to parameter variations and external disturbances. Furthermore, the speed of response is relatively slow because the swithching surface is a linear function. In order to overcome these problems, VSS with nonlinear sliding surface eliminating reaching phase is proposed. The validity of the proposed scheme is shown by results of simulations of simulations and experiments for the BLDC motor with variable load.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.301-307
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• 2013

MRU(motor reduction unit) for KTX is a assembled complex structure that is equipped with a lot of parts at the express train KTX and that is the core power source operating variable speeds. This study is recorded the dynamic characteristics analysis results tested by EMA which is done through the parts and assembly test, transient analysis and stoped train test in order to design the online monitoring system for KTX MRU. And the mode shapes result from critical vibration frequency explain the relation with variable speeds of express train over 250 km/hr. Also these variable speeds make variable operational frequencies at pinion, axle gear mesh frequency and normal bearing fault frequencies. As the specified speed can make resonance with natural frequencies of the MRU, for the train operating stability, this study also presents the MRU's critical speeds calculated by the each train speed.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.1-6
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• 2006

This paper proposes an SRM drive system to improve the drive efficiency of the hydraulic system. From the maximum hydraulic pressure and flow rate required by the hydraulic system, a proper SRM is designed and tested. The proposed SRM drive system controls oil pressure of the hydraulic system as well as motor speed. A 2.2[kW], 12/8-pole SR motor and digital controller based DSP are designed and tested for hydraulic pump system. The test results show that the system has some good features such as high efficiency and rapid response characteristics.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.328-334
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• 1999

A fish pump makes very important roles in an automation system of an aquaculture farm, thus it has been used widely in order to transfer fishes from one place to the other place automatically. In spite of its significant roles, the efforts for developing performance and promoting efficiency of the fish pump are not sufficient yet. In this paper, a method which makes the fish pump automation system is suggested. Automation of the fish pump can be accomplished by using variable voltage and variable frequency inverter system including induction motors. Especially, very simple logic to generate Pulse width Modulation(PWM) wave to control induction motor efficiently and three steps speed control method to regulate liquid quantity of the fish pump simply are suggested. Owing to the simplifies speed control and PWM wave generation technique, a cheaper microprocessor, 80C196KC, than a digital signal Processor(DSP) can be used to operate control algorithm in induction motor systems for real time control Also, a new idea of remote control for the simplifies novel inverter system by Programmable logic Controller(PLC) without special output unit, digital to analog converter(D/A), is suggested in this paper. Consequently the function of reliability, availability and serviceability of the fish pump system are developed. It will be expected to contribute expanding of application of the fish pump in aquaculture farms because the system can reduce energy consumption and some difficulties according to manual operation prominently.