• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1616-1618
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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 him-off angle compensator is used.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.317-319
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• 2005

In this paper, control algorithm for torque ripple compensation in DFIG wind power generation system is proposed. A simple PI controller is designed for the negative sequence voltage cancellation using negative sequence currents in the grid-side converter. As a result, the stator voltage contains only the positive sequence components and the torque pulsation of the generator is effectively compensated. Propose algorithm is confirmed with PSCAD simulation model.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.180-190
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• 2001

In this paper, a method of reducing torque ripples caused by phase winding inductances in BLDCM(Brushless DC Motor) drives is presented. In order to compensate the inductive current delays, commutation angle is controlled by the value compensating angle varied in accordance with rotational speed. Using the microprocessor AVR 8515, the proposed compensator is implemented and experiments are done with a 4-pole 3-phase BLDCM. The results show the remarkable reduction of torque ripple at whole speed ranges.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.11
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• pp.1153-1162
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• 1990

The torque ripple reduction method is studied to improve the speed fluctuation of permanent magnet flat type brushless DC motors. To reduce the torque ripple, this study developed the compensation method of the 5'th harmonics component of air gap flux waveform which pass through the driving coils. 1/2 inch VTR was considered. As the result of this study, we can reduce the torque ripple and the speed fluctuation of the capstan motor about 20% then before and we can obtain not only better characteristics of wow/flutter but more useful capstan motors which can be applied in the multi-function VTRs.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.380-385
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• 1998

This paper proposes a current control algorithm to reduce the torque ripple to commutation in unipolar PWM inverter-fed trapezoidal brushless dc motor drives. In this paper, we analyze the average voltage variation of the conducting phase due to commutation, and design a current controller to compensate for the average voltage variation. The proposed method predicts the duration of commutation to reduce the torque ripple due to over-compensation. Experimental results are presented that validate the proposed method.

• International Journal of Control, Automation, and Systems
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• v.4 no.1
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• pp.113-123
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• 2006

In this paper, an improved direct torque control (DTC) method for sensorless matrix converter drives is proposed which enables to minimize torque ripple, to obtain unity input power factor, and to achieve good sensorless speed-control performance in the low speed operation, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages of matrix converters with the advantages of the DTC strategy using space vector modulation and a flux deadbeat controller. To overcome the phase current distortion by the non-linearity of a matrix converter drive, the simple non-linearity compensation method using PQR power theory are presented in the proposed scheme. Experimental results are shown to illustrate the feasibility of the proposed strategy.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.4
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• pp.265-272
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• 2017

Velocity ripple in manufacturing processes reduces productivity and limits the precision of the product. In practice, the frequency and phase of velocity ripples always change minutely, which makes it impossible to compensate for the ripple by simply inserting an opposite feed-forward signal in the system. In this study, an active-phase compensation algorithm was developed to enable the velocity-ripple controller to track the phase change of the ripples in real time. The proposed controller can compensate for the velocity ripple whatever its cause, including disturbance by the torque ripple. The algorithm consists of three functional modules: the velocity-ripple extractor, the synchronized integrator, and the phase shifter. Experimental results showed that the proposed controller clearly reduces velocity ripples with phase variation.

• Journal of Power Electronics
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• v.5 no.2
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• pp.151-159
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• 2005

The errors generated from current measurement paths are inevitable, and they can be divided into two categories: offset error and scaling error. The current data including these errors cause periodic speed ripples which are one and two times the stator electrical frequency respectively. Since these undesirable ripples bring about harmful influences to motor driving systems, a compensation algorithm must be introduced to the control algorithm of the motor drive. In this paper, a new compensation algorithm is proposed. The signal of the integrator output of the d-axis current regulator is chosen and processed to compensate for the current measurement errors. Usually the d-axis current command is zero or constant to acquire the maximum torque or unity power factor in the ac drive system, and the output of the d-axis current regulator is nearly zero or constant as well. If the stator currents include the offset and scaling errors, the respective motor speed produces a ripple related to one and two times the stator electrical frequency, and the signal of the integrator output of the d-axis current regulator also produces the ripple as the motor speed does. The compensation of the current measurement errors is easily implemented to smooth the signal of the integrator output of the d-axis current regulator by subtracting the DC offset value or rescaling the gain of the hall sensor. Therefore, the proposed algorithm has several features: the robustness in the variation of the mechanical parameters, the application of the steady and transient state, the ease of implementation, and less computation time. The MATLAB simulation and experimental results are shown in order to verify the validity of the proposed current compensating algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.158-163
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• 2001

Current Source Inverter(CSI), operated in square wave mode, is more efficient thant the PWM CSI because of increased cost, greater complexity of control algorithm and substantial switching losses, EMI. But, the square wave output current of CSI, rich in low order harmonics produce motor torque ripples. Therefore, in this paper, describes active power filters for compensating square wave input current of current source induction motor. Also, notch filtering as compensation algorithm is employed. To confirm the validity of proposed system, PSIM simulation results are presented and discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1204-1210
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• 2016

The phase currents must be accurately measured to achieve the instantaneous torque control of AC motors. In general, those are measured using the current sensors. However, the measured current signals can include the offset errors and scaling errors by several components such as current sensors, analog amplifiers, noise filter circuits, and analog-to-digital converters. Therefore, the torque-controlled performance can be deteriorated by the current measurement errors. In this paper we have analyzed the influence caused by vector control of 2-phase induction motor when two errors are included in measured phase currents. Based on analyzed results, the compensation method is proposed without additional hardware. The proposed compensation method was applied vector-controlled inverter for 2-phase induction motor of 360[W] class and verified through computer simulations and experiments.