• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.12
• /
• pp.623-627
• /
• 2006

This paper deals with the optimum rotor design solution on torque ripple reduction for a SynRM with concentrated winding using response surface methodology (RSM). The RSM has been achieved to use the experimental design method in combination with finite element method (FEM)and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables. Comparisons are given with characteristics of a SynRM according to flux barrier number, flux barrier width variation, respectively.

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

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.2
• /
• pp.333-337
• /
• 2010

In this paper, an advanced torque control scheme of Switched Reluctance Motor(SRM) using modified non-linear logical TSF (Torque Sharing Function) with PWM is presented. In the proposed control scheme, a simple calculation of PWM duty ratio and switching rules from DITC(Direct Instantaneous Torque Control) can reduce the torque ripple with fixed switching frequency. The proposed control scheme is verified by the computer simulations and experimental results.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.4
• /
• pp.945-950
• /
• 2013

This paper deals with the ellipse permanent magnet machines for the minimization of torque ripple based on electromagnetic field theory. On the basis of a magnetic vector potential and a two dimensional (2-D) polar system, analytical solutions for flux density due to permanent magnet (PM) and current are obtained. In particular, the analytical solutions for mathematical expressions of magnets with different circumferential thicknesses can be solved introducing improved magnetization modeling techniques. The analytical results are validated extensively be nonlinear finite element solutions, a reduction of torque ripple can be achieved.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.4B no.4
• /
• pp.196-200
• /
• 2004

This paper presents a method to reduce the commutation torque ripple in a position sensorless brushless DC motor drive. To compensate the commutation torque ripple considerably, the duration of commutation must be known. The proposed method measures the duration of commutation from the terminal voltage of the motor, calculates a PWM duty ratio using the measured commutation interval to suppress the commutation torque ripple, and applies it to the calculated PWM duty ratio only during the next commutation. Experimental results show that pulsating currents and vibrations are considerably reduced when the proposed method is applied to a position sensorless brushless DC motor drive for the air-conditioner compressor.

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

• Journal of Power Electronics
• /
• v.9 no.3
• /
• pp.396-402
• /
• 2009

A DC/DC converter generally needs to work under high switching frequency when used as an adjustable power supply to reduce the size of magnetic elements such as inductors, transformers and capacitors, but with the rising of the switch frequency, the switch losses will increase and the efficiency will reduce. Recently, to solve these problems, research is actively being done on a soft switching method that can be applied under high frequency and on a PWM converter that can be applied under low frequency such as a multi-level topology. In this paper a novel DC-DC conversion method for reducing the ripple of output voltage is proposed. In the proposed converter, buck converters are connected in series to generate the output voltage. By using this method, the ripple of output voltage can be reduced compared to a conventional buck converter. Particularly when output voltage is low, the number of acting switching elements is less and the result of ripple reduction is more obvious. It is expected that the converter proposed in this paper could be very useful in the case of wide-range output voltage.

• Journal of Magnetics
• /
• v.17 no.2
• /
• pp.109-114
• /
• 2012

The torque characteristics of a surface-mounted permanent magnet synchronous motor (SPMSM) are analyzed in this study. The harmonics of the back electromotive force (EMF) and cogging torque are analyzed by the finite element method to study their effects on the torque ripple. Although low cogging torque can be achieved by varying geometric parameters such as the permanent magnet (PM) offset and notch depth on the stator teeth, the torque ripple is increased in some cases. The analysis results show that the ripple of the generated torque is determined by not only the amplitudes but also the phases of harmonics for the back EMF and cogging torque.

• Journal of Industrial Technology
• /
• v.24 no.A
• /
• pp.109-117
• /
• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

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