• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.449-454
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• 2005

Brushless DC Motor(PM BLDCM) is widely used in industrial applications due to its high efficiency and power density. In order to increase reliability and reduce system cost, this paper studies particularly applicable method for sensorless PM BLDCM drive system. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition, and is practically free of noise that can be introduced by the inverter switching, making this a robust sensing method. As a result, the method described here is not sensitive to filtering delays, allowing the motor to achieve a good performance over a wide speed range. In addition, a simple starting method and a speed estimation approach are also proposed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.48-56
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• 2006

This paper studies particularly applicable method for sensorless PM BLDC motor drive system. The waveform of the motor internal voltages(or back emf) contains a fundamental and higher order frequency harmonics. Therefore the third harmonic component is extracted from the stator phase voltage. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition. Also because of low resolution of estimated signal obtained by the proposed sensorless algorithm, to improve the wide range of speed response characteristic more exactly, we propose the rotor position signal synthesizer using PLL circuit based on estimated signals. Some experimental results are provided to demonstrate the validity of the proposed control method.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.65-72
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• 2009

The new method is proposed to improve high speed detection of grid voltage phase and magnitude during a voltage dip due to a grid faults. Usually, A LPF(Low Pass Filter) is used in the feedback loop of PLL (Phase Locked Loop) system because the measured grid voltage contains harmonic distortions and sensor noises. so, a new design method of the loop gain of the PI -type controller in the PLL system is proposed with the consideration of the dynamics of the LPF. As a result, a better transient response can be obtained with the proposed design method. The LPF frequency and PI controller gain are designed in coordination according to the steady state and dynamic performance requirement. This paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the lab-scale experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.108-114
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• 2009

This paper proposes the new hybrid adaptive controller for fast response time and precision control of automation system which exist deadzone or non-linearity of system. The proposed system, which provides the improvement in terms of the control region in high speed and precision control, first used the fuzzy control method for fast response time and when the error reaches the preset value, used the PLL method designing PFD improved jitter for precision control. The new designed PFD improves the jitter noise and response characteristic without generating deadzone. The theoretical and experimental studies have been carried out. The presented results from the above investigation show considerably improved performance in the position control of automation system.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.146-148
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• 1997

This paper investigates the position sensorless control of switched reluctance motor. The system consists of the position detection circuit by the new phase detection algorithm, digital logic commutator, PLL for speed control and 4-phase inverter. The performances in the proposed system are verified through the experiment.

• 전기의세계
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• v.30 no.11
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• pp.717-727
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• 1981

The phase-locked loop technique developed in the 1930's has many advantages when applied to speed control. The speed control and analysis of a three phase induction motor using the PLL are described in this paper. In this system, the phase frequency detector (PFD) compares the actual motor speed from the pulses received from a shaft encoder and desired speed, and the difference adjusts the frequency of the inverter that feeds the motor, and excellent speed regulation in the order of 0.035(%) has been-obtained. A linear continuous model of the drive is developed and system response is analysed using conventional root locus techniques. Various compensating filters and feedback signals are considered and the need for addition of derivative feedback is shown. A sampled data model is used to study the effects of discrete PFD output. Stability limitson speed are predicted. A drive was implimented and experimental results are presented to verify theoretical predictions.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.898-904
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• 2012

This paper presents a ride-through skill of PMSG wind turbine system under the distorted and unbalanced grid voltage dips. When voltage dips occur in the grid, pitch control and generator speed control as well as a parallel resistor of DC-link help to keep the turbine's safety. Modern grid code requires a wind turbine to supply reactive currents to help voltage recovery after grid faults clearance. In order to supply reactive currents to the grid in case of the distortedly unbalanced grid voltage dips, a special PLL is needed to control the grid side converter and to regulate the grid voltages symmetrically. The proposed method is applied to 2MW multi-pole PMSG wind turbine system, and verified by simulation.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.665-669
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• 2004

Generally, Slotless PM BLDC drive system is necessary that the three Hall-ICs evenly be distributed around the stator circumference and encoder be installed in case of the 3 phase motor. So, the Hall-ICs are set up in this motor to detect the main flux from the rotor, and the output signal from Hall-ICs is used to drive a power transistor to control the winding current. However, instead of using three Hall-ICs and encoder, we used only two Hall-ICs for the permanent magnet rotor position and for the speed feedback signals, and also for a microcontroller of 16-bit type (80C196KC) with the 3 phase Slotless PM BLDC whose six stator and two rotor designed. Two Hall-IC Hc and $H_B$ are placed on the endplate at 120 degree intervals, and with these elements, we can estimate information of the others phase in sequence through a rotating rotor.

• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.45-50
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• 2015

This paper suggests the sensor-less speed control of PMSM (Permanent Magnet Synchronous Motor) without the position sensor of oil-free air compressor. It estimated d and q axis back electro motive force using Back-EMF (Electro motive Force) observer to control sensor-less speed of PMSM. Also it used the method that tracks the information of rotor position and speed using PLL (Phase Locked Loop) based on estimated d and q axis Back-EMF. The sensor-less speed control of PMSM for oil air compressor application is carried out with the introduced rotor position and speed tracking method. In this paper, the experimental characterization of the sensor-less drive is provided to verify the accuracy of the estimated position and the performance of sensor-less control is analyzed by results obtained from the experiment. Moreover, the potential of PMSM sensor-less drive in industrial application such as compressor drive is also examined.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.332-335
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• 1990

A digital phase-locked loop speed control system of a self-controlled permanent magnet synchronous mortar fed by a voltage source inverter is presented. This paper discribes the hardware and software design of the system. Variable speed control system for self-controlled permanent magnet synchronous motor is proposed. Simulation results demonstrate the validity of proposed methods. This proposed control technique is implemented by using a microprocessor-based system.