• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.122-125
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• 2005

A novel torque ripple reduction scheme of single-phase SRM with high power factor is presented. The proposed SRM drive has one additional active switches in the conventional asymmetric inverter. In order to get a higher power factor, the source current is controlled sinusoidal, And additional excitation current is added from charge capacitor due to torque ripple reduction. The switching period of source and charged voltage is controlled properly to get unity power factor and torque ripple reduction. The characteristics and validity of the proposed scheme is discussed with some simulation results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.583-584
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.533-539
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• 1997

Pressure ripple of hydraulic vane pump results form flow ripple due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a ba;anced type vane pump, cam ring curve is important factor to influence the flow ripple. Therefore, to reduce the now ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring, and examined into the role of notch and radius reduction ratio.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.280-288
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• 1997

In this paper, we will show that the torque ripple in closed-loop drives of permanent magnet stepping motors is reduced as properly selected lead angle control method. We propose an instantaneous torque equation, which is the function of lead angle, to estimate the influence on torque ripple. We design a closed-loop lead angle control system based on the proposed instantaneous torque equation and measure the instantaneous torque in various excitation modes. It is shown that torque ripple is greatly reduced, as seen from the experimental results as well as from the computer simulation results. For example, torque ripple reduced from 78.25% to 46.82% in the case of 50 PPS single-phase excitation mode operation.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.145-150
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• 2010

This paper deals with reduction of torque ripple in a brushless DC motor with input voltage control. The commutation torque ripple can be controlled with varying input voltage, but cogging torque is independent on it. So, in this paper a strategy for minimizing torque ripple is proposed by offsetting the cogging torque with deliberate voltage control. The optimal condition is determined with variable voltage levels and advance angles. As results, it is shown that the method causes 63% decrease of torque ripple.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.1
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• pp.91-100
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• 2002

This paper deals with the ripple reduction of the electromagnetic torque developed in IPMSM(Interior Permanent Magnet Synchronous Motor). Generally, torque ripple is an important causes of vibration and noise of motor. For reducing torque ripple in IPM with nonsinusoidal EMF, the optimal current which is able to control maximum torque/ampere is considered to be introduced In the proposed method. The fact of torque ripple being reduced when the optimal current Is used in motor is verified through simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.220-226
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• 2014

Input current ripple and harmonic components of the power device are main causes of electromagnetic interference (EMI). Although the discontinuous conduction mode (DCM) operation can reduce harmonic components of the power device by reducing reverse recovery current of diode and turn-off voltage spikes of the switch, input current ripple increases due to high peak to peak inductor current. Therefore, in this paper, frequency control algorithm is proposed to reduce the input current ripple of DCM operated interleaved boost converter. In the proposed algorithm, duty ratio is fixed either 0.33 or 0.67 to minimize the input current ripple and the switching frequency is controlled according to operating conditions. 600 W 3-phase interleaved boost converter prototype system is built to verify proposed algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.46-52
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• 2021

This study proposes a feedforward compensation control method to reduce 120 Hz output voltage ripple in a single-phase AC/DC rectifier system composed of PFC and LLC resonant converters. The proposed method compensates for the voltage ripple of the DC-link by using the AC input and DC output power difference, and then reduces the final output voltage ripple component of 120 Hz through feedforward compensation based on the linearized frequency gain curve of the LLC resonant converter. Through simulation and experimental results, the validity of the ripple reduction performance was verified by comparing the conventional PI controller and the proposed feedforward compensation method.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.963_964
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• 2009

This paper presents an output ripple reduction of Active-Clamp Forward Converter, which is mainly composed of interleaving two active-clamping forward converters. By interleaving, Output ripple is reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve ZVS during the dead times. The duty cycles are not limited to be equal and within 50%. The complementary switching and the resulted interleaved output inductor currents diminish the current ripple in output capacitors. Accordingly, the smaller output chokes and capacitors lower the converter volume and increase the power density. Detailed analysis of this ouput reduction of Active-Clamp Forward Converter is described.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.232-234
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• 2005

In this paper, A fuzzy logic based turn-off angle compensator for torque ripple reduction in a linear switched reluctance motor is proposed. The turn-off angle, as a complex function of motor speed and current, is automatically changed for a wide speed range to reduce torque ripple. Simulation results are presented that show ripple reduction when the turn-off angle compensator is used.