• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.249-256
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• 2014

This paper proposes a torque control method of permanent magnet synchronous motor, which has small torque ripple. The proposed control method is using the finite control set-model predictive control(FCS-MPC) strategy. An optimal input voltage vector minimizing a cost function is chosen among 6 passible active input voltage vectors following the FCS-MPC strategy. Then, a modulation factor for the optimal input voltage vector is computed to minimize the torque ripple. Thus, the proposed control method yields fast torque response and small torque ripple. The efficacy of the proposed method was verified through simulation and experiment.

• Journal of Power Electronics
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• v.19 no.4
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• pp.881-893
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• 2019

This paper proposes a practical sliding-mode controller design for shaping the impedances of cascaded boost-converter power decoupling circuits for reducing the second order harmonic ripple in photovoltaic (PV) current. The cascaded double-boost converter, when used as power decoupling circuit, has some advantages in terms of a high step-up voltage-ratio, a small number of switches and a better efficiency when compared to conventional topologies. From these features, it can be seen that this topology is suitable for residential (PV) rooftop systems. However, a robust controller design capable of rejecting double frequency inverter ripple from passing to the (PV) source is a challenge. The design constraints are related to the principle of the impedance-shaping technique to maximize the output impedance of the input-side boost converter, to block the double frequency PV current ripple component, and to prevent it from passing to the source without degrading the system dynamic responses. The design has a small recovery time in the presence of transients with a low overshoot or undershoot. Moreover, the proposed controller ensures that the ripple component swings freely within a voltage-gap between the (PV) and the DC-link voltages by the small capacitance of the auxiliary DC-link for electrolytic-capacitor elimination. The second boost controls the main DC-link voltage tightly within a satisfactory ripple range. The inverter controller performs maximum power point tracking (MPPT) for the input voltage source using ripple correlation control (RCC). The robustness of the proposed control was verified by varying system parameters under different load conditions. Finally, the proposed controller was verified by simulation and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.312-316
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• 2005

The single phase induction motor has been commonly applied to small-sized electrical appliances because of its low cost, but it has low efficiency and large torque ripple, and it is incapable of speed control. However, two-phase induction motors have small torque ripple, high efficiency and variable speed control, because they are inverter fed. In this paper, the dynamic characteristics of the two-phase induction motor, such as the torque ripple, current and speed, are analyzed by using the time-stepping finite element method, and compared with the cage-type single phase induction motor.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.523-524
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• 2008

Proposed battery charger is a economic candidate because that is simple and small size. The circuit has linearly operational power stage. That use small size buffer with small driving current and large power MOS gate capacitance. The simulation result show that charging current is stable and has low ripple.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.542-546
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• 2004

This paper presents a technique to reduce the low frequency ripple voltage of the dc output in a BIFRED converter with a small-sized energy storage capacitor. The proposed pulse width control method can be effectively used to suppress the low frequency ripple appeared in the dc output and still shows generally good performance such as low THD of input line current and high power factor. Using the small-sized energy storage capacitor, it has better merits of low cost and small size than a conventional BIFRED converter. The proposed technique is illustrated its validity and effectiveness through simulations.

• Journal of Power Electronics
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• v.5 no.3
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• pp.190-197
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• 2005

This paper presents a technique to reduce the low frequency ripple voltage of the dc output in a BIFRED converter with a small-sized energy storage capacitor. The proposed pulse width control method can be effectively used to suppress the low frequency ripple appeared in the dc output and still maintains generally good performance such as low THD of input line current and a high power factor. Using the small-sized energy storage capacitor, it has better merits of low cost and smaller size than a conventional BIFRED converter. The proposed technique is illustrated its validity and effectiveness through simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.785-790
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• 2011

This paper presents the effects of an assisting motor torque ripple on a driver's steering feeling using a simulink. The EPS(Electric Power Steering) System is modeled as a 5 degrees of freedom for simulation. To find out the influence of a torque ripple on a driver's steering feeling, which is the purpose of this study, we observed the assisting torque in various different speeds, when the torque ripple increased by 0%~40%. The torque ripple had a small but definite influence on the assisting torque, and it had a greater influence in low speeds rather than high speeds.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.12-14
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• 1995

It is necessary to analyze exactly the torque ripple components in the harmonics as to decrease the torque ripple. Lower harmonics influence mainly on torque ripple. Among the harmonics, the pairs of 5's, 7's and 11's, 13's are dominant, and the magnitude of each pairs of current harmonics are very significant. Therefore, for decreasing the torque ripple, current harmonic pairs of 6n ${\pm}$1's orders must be simultaneously eliminated. In the case of eliminating one of current harmonic pairs, even though the magnitude of the current harmonics is small, It has great effect on torque ripple.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.6
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• pp.376-382
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• 1988

A small-signal low-frequency disturbance of the input line affects the regulated-output voltage of the series resonant converter. To mitigate the detrimental effect, the output feedback PI-controller is employed. Small-signal linear models are represented to characterize the closed loop series resonant converter system. Design equations for the PI-controller which satisfy stability and percent ripple conditions are derived from the closed-loop linear model. Experimental results are presented which show excellent correlation with theory.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.117-124
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• 2007

The pressure ripple in most hydraulic systems is the root cause of their noise and vibration. This paper reduced the pressure ripple using side branch hose for an axial piston pump applied to small excavator. First, in calculating open area, a new method using groove area of valve plate is proposed. Simulation model in AMESim environment is developed to verify proposed method, find effective length and diameter of branch hose. Finally, the comparisons with experiment results show that the proposed method is more effective than previous method in reducing the pressure ripple.