• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.397-398
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• 2013

Fairchild Green Mode off line buck switch for low standby power consumption and high reliability is presented. By reducing operating current and optimizing switching frequency, 20mW power consumption is achieved. High performance trans-conductance amplifier and green mode function improve the ripple and regulation in the output voltage. The conventional $FPS^{TM}$ buck and novel Fairchild buck switch are compared to show the improvement of performance. Experimental results are showed using 2W evaluation board.

• Journal of IKEEE
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• v.24 no.4
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• pp.1104-1108
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• 2020

This paper propose a variable proportional resonant feedforward algorithm for reducing the speed ripple of a three-phase permanent magnet synchronous motor. In general, the torque ripples can be generated by electrical pulsation due to current measurement errors and dead time and mechanical pulsation because of rotor eccentricity and eccentric load. These torque pulsations can cause speed pulsations of the motor and degrade the operating performance of the motor drive system. Therefore, in this paper, the factors of the speed ripple is analyzed and an algorithm to reduce the speed ripple is proposed. The proposed algorithm applied a variable proportional resonant controller in order to reduce the specific operating frequency included in the speed pulsation, and utilized a feedforward compensation controller structure to perform the compensation operation. The proposed algorithm is verified through various experiments.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.142-144
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• 2007

This paper proposes problem improvement in existing method about three-phase current reconstruction method and present minimum voltage injection method and Smooth voltage injection method in single current sensor for washing machine motor drive. So, presented wash noise improvement method through ripple reduction in inverter. The simulation and experimental results are given to show the effectiveness of the proposed method for reconstructing the phase currents and reducing the noises.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1104-1107
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• 1992

Voltage controlled current regulated PWM(pulse width modulation) of VSI (voltage source inverter) is proposed. Adopting one degree of freedom, the voltage, the current controller shows much more improvement than conventional ones not using this method. The voltage controller or this proposal needs load's parameters, torque value, rotational speed. This voltage controller is located at converter part which links AC source and DC bus. With this proposed method, duty ratio of the inverter's switching is nearly unity for all speed and torque range. Hence, this method gets many advantages such as reducing current ripple, thermal loss, and noises and improving control performances. Theoretical approach to this voltage-current controller is performed, and the results are presented.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.212-216
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• 1998

For a Switched Reluctance Motor(SRM) drive, the important things are 1) reducing torque ripple, 2) improving efficiency, 3) sensorless speed control, 4) accurate position. The position information impotant for the efficiency and smoothness drives. Since SRMs characteristics are nonlinear. It is difficult to estimated phase current in saturation region. This paper describes a method for indirect sensing of the rotor position in SRM which use both voltage and current. The method obtains rotor position by using unconducting phase. The information about the rotor position is achieved by differentiating the unconducting phase current or the voltage gradient. And then, this paper presents a torque control with indirect rotor position detection methods. This torque control is achieved by developing a detailed nonlinear model of the motor.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.10
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• pp.530-536
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• 1999

This paper investigates effects of segmented poles on exciting forces such as cogging torque, BEMF, phase current, torque ripple and local forces. Cogging torque, BEMF and local force are determined by FEM analysis and phase current is calculated using voltage equations after determining BEMF and phase inductance. Effective dead zones at pole separations result in wider than the physical dead zones due to leakage field during magnetization. Due to the existence of dead zones, there exist additional exciting harmonics of the cogging torque which play adverse effect on vibration and noise performance. The magnitude of BEMF is decreased and the waveforms are also distorted depending on dead zone positions. Segmented poles inevitably cause uneven magnetic field distribution at pole separations which introduces additional harmonics of exciting forces which are detrimental to structural to structural resonances. They also decrease motor efficiency by reducing effective phase BEMF.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.54-59
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• 1996

As the current shape of SRM is of pulse type and changed by the motor parameters and drive conditions, the influences on the drive efficiency by control method are more than other types of motors. In this paper, a proper excitation condition to drive a SRM with high efficiency is proposed and tested. It is derived from the conditions that the phase current of a SRM is to be flat-topped at various drive. The saturation effect of magnetic circuit is accounted for more accurate analysis. Experimental tests are executed to verify the proposed excitation method. This drive system is easy to commutate and also advantageous in reducing torque ripple. (author). 6 refs., 10 figs., 1 tab.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.24-25
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• 2017

In this paper, a low cost bridgeless interleaved power factor correction topology for electric vehicle charger application is proposed. With the proposed topology the number of switches, inductors, current sensors and associated circuits can be reduced, thereby reducing the cost of the system as compared to the conventional bridgeless PFC circuit. The reduced input current ripple by the proposed interleaved topology makes it suitable for high power applications such as electric vehicle chargers since it can reduce the size of the inductor core and the Electro Magnetic Interference (EMI) problem. In the proposed topology only one current sensor is required. All the boost inductor currents can be reconstructed by sampling the output current and used to control the input current. Therefore the typical problem caused by the unequal current gain of each current sensor inherently does not exist in the proposed topology. In addition the current sharing between converters can be achieved more accurately and the high frequency distortion is decreased. The performance of the proposed converter is verified by the experimental results with a prototype of 6.6kW bridgeless interleaved PFC circuit.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.143-148
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• 2023

Among the characteristics of SRM, due to nonlinearity, it is difficult to properly operate to form maximum torque and minimum torque pulsation. In addition, in the case of fixed switching angle control, torque formation according to speed variation is unstable, thereby reducing efficiency. Therefore, active switching angle control according to speed variation is required. Therefore, active switching angle control according to speed variation is required. In this paper, a method for improving driving performance by reducing torque ripple by automatic control of the advance angle and increasing output torque was sought from the problem caused by the nonlinearity of the SRM. In addition, the optimal operation of SRM due to the switching variable according to the performance of the hysteretic current controller was examined.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.41-48
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• 2004

In this paper, a PFC(Power Factor Correction) electronic ballast with constant voltage-fed is proposed. The proposed PFC electronic ballast is combined of a high-efficiency boost converter and a conventional half bridge inverter. It is proved that the ripple of input-current and the input-current's harmonic of the proposed PFC electronic ballast are reduced using the voltage divider and soft-switching technique. It is demonstrated that simulation results for fluorescent lamp correspond with theoretical analysis.