• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.1-8
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• 2019

The electromagnetic forces generate a torque on the gimbal motor, and changes in the coil current causes torque ripple. This affects the gimbals' speed and results to unstable satellite attitude. It is therefore essential to reduce the torque ripple of the gimble motor with the aim of improving the attitude control accuracy of the satellite. This paper theoretically analyzes the torque generated from the modeling of a motor for general concentrated winding and distributed winding. The prototype was designed and fabricated through selection of the winding that reduces the torque ripple through simulation results. The results of the magnetic fields' theoretical analysis and the back electromotive force of the prototype were compared with the calibrated results for verification of conformity and manufacture of the design. The low-speed test proved that the torque ripple is reduced by improving the speed stability.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.91-94
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• 2006

Miniature BLDC is widely used in industrial applications and especially medical appliances because of there character that high driving efficiency and high torque characteristic. However torque ripple of a high speed miniature BLDC is serous in switching period cue to the very electrical time constant. This paper present instant voltage and current control for torque ripple reduction of a high speed miniature BLDC. Computer simulation and experiment test for 40,000 rpm miniature BLDC show the verification of the proposed control method.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.627-628
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• 2006

Miniature BLDC is widely used in industrial applications because of high driving efficiency and high torque characteristic. Otherwise the general BLDC, torque ripple of a high speed miniature BLDC is serous during conduction due to the very low electrical time constant. This paper present instant voltage and current control for torque ripple reduction of a high speed miniature BLDC. Computer simulation and experiment test for 40,000 rpm miniature BLDC show the verification of the proposed control method.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1177-1186
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• 2017

This paper presents a torque ripple reduction method of direct torque control (DTC) using fuzzy controller with optimal selection strategy of voltage vectors in a five-phase induction motor. The conventional DTC method has some drawbacks. First, switching frequency changes according to the hysteresis bands and motor's speed. Second, the torque ripple is rapidly increased in long control period. In order to solve these problems, some/most papers have proposed torque ripple reduction methods by using the optimal duty ratio of the non-zero voltage vector. However, these methods are complicated in accordance with the parameter. If this drawback is eliminated, the torque ripple can be reduced compared with conventional method. In addition, the DTC can be simply controlled without the use of the parameter. Therefore, the proposed algorithm is changing the voltage vector insertion time by using the designed fuzzy controller. Also, the optimized voltage vector selection method is used in accordance with the torque error. Simulation and experimental results show effectiveness of the proposed control algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.6
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• pp.445-454
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• 2002

Torque ripple control of brushless DC motors has been the persisting issue of the servo drive systems in which the speed fluctuation, vibration and acoustic noise should be minimized. In this paper, a novel approach to achieve the ripple-free torque control with maximum efficiency based on the d-q reference frame is presented and analyzed. The proposed approach can provide the optimized phase current waveforms over wide speed range incorporating cogging torque compensation without an access to the neutral point of the motor windings. Moreover, the undesirable errors caused by the assumptions such as 3 phase balance or symmetry of the phase back EMF between electrical cycles, which are related with the manufacturing imperfections, can be also eliminated. As a result, the proposed approach provides a simple and clear way to obtain the optimal motor excitation currents. A hysteresis current control system is employed to produce high-frequency electromagnetic torque ripples for compensation. The validity and applicability of the proposed control scheme to real situations are verified through the simulations and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.174-182
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• 2002

This paper presents a comprehensive study on reducing commutation torque ripples generated in brushless DC motor drives with only a single do-link current sensor provided. In such drives, commutation torque ripple suppression techniques that are practically effective in low speed as well as high speed regions are scarcely found. The commutation compensation technique proposed here is based on a strategy that the current slopes of the incoming and the outgoing phases during the commutation interval can be equalized by a proper duty-ratio control. Being directly linked with deadbeat current control scheme, the proposed control method accomplishes suppression of the spikes and dips superimposed on the current and torque responses during the commutation intervals of the inverter. Effectiveness of the proposed control method is verified through simulations and experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.48-54
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• 2014

This paper discusses study of torque ripple minimization employing an improved TDF(torque distribution function)-based instantaneous torque control to reduce acoustic noise and vibration problem of the SRM. As the flux linkage of the SRM is a nonlinear function of phase current and rotor position, design of optimal controller for the SRM is quite complicated. Hence, an accurate mathematical model considering the nonlinearity of the SRM is required. An improved TDF based torque control has been proposed in order to reduce the toque ripple at high speed operation. Dynamic simulation using Matlab/Simulink as well as Finite Element Analysis is presented. A prototype SRM for electric vehicle traction has been manufactured to validate the experimental results comparing the dynamic simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.2
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• pp.49-56
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• 1997

Switched Reluctance Motors(SRMs) have a considerable inherent torque ripple due to the driving characteristics of pulse current waveform and the nonlinear variation inductance profile. This paper describes a current shape characteristics to effect a torque ripple reduction, and one pulse mode switching control method is proposed to minimize torque ripple of a switched reluctance motor regardless of speed and load condition by regulating tow parameters, such as, advance angle and exciting voltage. The experiments are performed to verify the capability of proposed switching method on 6/4 salient type SRM.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.682-688
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• 2008

Transverse flux machine (TFM) has been considered as a promising driving machine especially at the low-speed applications because it has higher power density, torque and efficiency than the conventional electrical motors. However, it has complicated structure, large torque ripple and sometimes unbalanced magnetic force due to its inherent structure. This paper investigates the characteristics of torque ripple and unbalanced magnetic force of a rotatory two-phase TFM due to the teeth geometry by using the 3-dimensional finite element method, and it develops a rotatory two-phase TFM with herringbone teeth to reduce the torque ripple as well as to eliminate the unbalanced magnetic force.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1721-1724
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• 2017

This paper presents a numerical optimization technique to reduce input current and torque ripple of the low voltage BLDC motor using core, coil and switching angle optimization. The optimization technique is employed using the generalized response surface method(RSM) and sampling minimization technique with FEM. A 50W 24V BLDC motor is used to verify the proposed algorithm. As optimizing results, the input current is reduced from 2.46 to 2.11[A], and the input power is reduced from 59 [W] to 51 [W] at the speed of 1000 [rpm]. Also, applied the same optimization algorithm, the torque ripple is reduced about 7.4 %. It is confirmed that the proposed technique is a reasonably useful tool to reduce the consuming current and torque ripple of the low voltage BLDC motor for a compact and efficient design.