• Title/Summary/Keyword: torque ripple

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Torque Ripple Reduction for Permanent Magnet Synchronous Motor using Harmonic Current Injection (고조파 전류를 이용한 영구자석형 동기 전동기의 토크 리플 저감)

  • Kwon, Soon-O;Lee, Jeong-Jong;Lee, Geun-Ho;Hong, Jung-Pyo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1930-1935
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    • 2009
  • This paper deals with the torque ripple reduction of permanent magnet synchronous motor using harmonic current injection. Torque ripple of electric motor reduces system stability and performances, therefore efforts to reduce torque ripple are exerted in the design process. Torque ripple can be reduced by appropriate pole/slot combination, skew of rotor or stator, design of magnetic circuit, etc. In addition, torque ripple can be also reduced by input voltage and current, and many researches have been conducted to reduce torque ripple for six-step drive. Torque ripple reduction for current vector controlled permanent magnet synchronous motor also have been conducted and verified by investigating back emf wave form. Torque ripple reduction in this paper started from getting torque profile according to input current and electrical angle calculated by FEA, then instantaneous currents at each electrical angles for constant torque are calculated and applied to experiments. Therefore, 0% of torque ripple can be obtained theoretically with harmonic current injection. In order to maximize the effect of torque ripple reduction, a BLDC motor having high harmonic component of back emf is chosen. With sinusoidal current drive, over 100% of torque ripple is obtained initially, then 0.5 % of torque ripple is obtained by FEA using harmonic current injection. The effect is verified by experiment and the presented method can be effectively applicable to Electric Power Steering(EPS).

Compensation Algorithm for Periodic Torque Ripple of AC Motors (교류전동기의 주기적인 토크리플 보상알고리즘)

  • Kim, Byong-Seob;Choi, Jong-Woo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.11 no.6
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    • pp.551-557
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    • 2006
  • The electrical frequency synchronized periodic torque ripple exits in the AC motor. There are various sources of torque ripple in AC motor such as current measurement error, dead time, etc. This paper proposes a compensation algorithm which suppresses undesired side effect known as the periodic torque ripple of AC motor. The torque ripple compensation classified as the speed ripple detector and torque ripple compensator. This paper proves a speed ripple minimization at steady state by analysis of torque ripple compensator. A new speed ripple detector improves the performance of torque ripple compensation algorithm. The simulation and experimental results show that the compensation algorithm is effective and the torque ripple compensation method improves the performance of speed ripple detector by eliminating torque ripples effectively.

Active Cancellation of PMSM Torque Ripple Caused by Magnetic Saturation for EPS Applications

  • Lee, Geun-Ho
    • Journal of Power Electronics
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    • v.10 no.2
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    • pp.176-180
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    • 2010
  • This paper deals with a control method to reduce the torque ripple of a permanent magnet synchronous motor (PMSM) for electric power steering (EPS) systems. Such an application requires a very low torque ripple in order to maintain a good steering feel. However, because of spatial limitations, it cannot help having a partial saturation in the iron core of the PMSM for an EPS system, and this saturation results in a significant torque ripple. Thus, this paper analyzes the torque ripple caused by the magnetic saturation of a PMSM and proposes a method with respect to inductance measurement to verify the partial saturation. In addition, it is shown that a compensation current is needed in order to minimize the torque ripple when a PMSM is driven in the high torque region. The estimation process of the current and the torque ripple decreased by the current are presented and verified with test results.

Compensation of torque ripple of brushless DC motor using feedforward method (Feedforwad 방법을 이용한 BLDC 모터의 토크리플 보상)

  • 장호연;박기철;장평훈
    • 제어로봇시스템학회:학술대회논문집
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    • pp.736-739
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    • 1997
  • In recent years, there has been a renewed interest in the BLDC motor as a research subject. In this paper we inspect sources of the torque ripple, which is one of the elements causing performance depreciation of BLDC motors. Based on the inspected sources of the torque ripple, feedforward compensation methods are proposed to reduce the size of torque ripple. The effectiveness of the proposed methods is verified with experiments.

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Torque ripple reduction of a closed-loop driven permanent magnet stepping motor by lead angle control (Lead angle 제어에 의한 폐루프 운전 영구자석형 스테핑 전동기의 토오크 리플 저감)

  • Lee, Hyun-Chang;Jun, Ho-Ik;Woo, Kwang-Joon
    • 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.

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Reduction of Torque Ripple in a BLDC Motor Using an Improved Voltage Control (개선된 전압제어를 이용한 BLDC 전동기의 토크맥동저감)

  • Song, Jeong-Hyun;Jang, Jin-Seok;Kim, Byung-Taek
    • 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.

Torque Ripple Minimization in Direct Torque Control of Brushless DC Motor

  • Li, Zhenguo;Zhang, Songfa;Zhou, Shenghai;Ahn, Jin-Woo
    • Journal of Electrical Engineering and Technology
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    • v.9 no.5
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    • pp.1569-1576
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    • 2014
  • This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge $120^{\circ}$ conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.

Influence of Torque Ripple Caused by Current Harmonics on Induction Motor Fed PWM Inverter (PWM 인버터로 구동되는 유도전동기 시스템에서 고조파가 토오크 맥동에 미치는 영향에 관한 연구)

  • Baek, S.H.;Kim, Y.;Ham, J.G.;Maeng, I.J.;Sohn, J.M.
    • Proceedings of the KIEE Conference
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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.

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Analysis of the Acoustic Noise Characteristics by Controlling Lead Angle in Brushless DC Motors (진상각 제어에 따른 BLDC 전동기의 소음 특성 해석)

  • 황상문;김경태;정승규
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.1
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    • pp.101-109
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    • 2000
  • Mutual torque ripple in a brushless DC motor is the main source of acoustic noise, especially fur motor operation with high speed and torque. This paper presents a method to obtain mutual torque ripple to identify acoustic noise source. Mutual torque ripple can be determined by analyzing phase current shape and magnetic circuit with different lead angles. Current shape is determined by state space model of voltage equation with the use of inductance calculated by FEM, and confirmed by experimental results. Mutual torque ripple is also determined by FEM analysis for the calculated current shape. Acoustic noise experiment reveals that mutual torque ripple with different lead angle is one of the main sources for noise generation in a brushless DC motor.

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A Commutations Strategy for Torque Ripple Reduction of Sensorless Drive for Brushless DC Motors (BLDC 전동기용 센서리스 드라이브의 토크 리플 저감을 위한 전환 방법에 관한 연구)

  • 여형기;김태형;이광운;박정배;유지윤
    • The Transactions of the Korean Institute of Power Electronics
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    • v.3 no.3
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    • pp.199-205
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    • 1998
  • Brushless DC motors have trapezoidal back-EMF waveform. Theoretically it should be fed with rectangular phase current in order to produce torque ripple free. Because it is drived by a voltage source inverter, perfect rectangular phase current can not available and therefore produce torque ripple. In this paper, the torque ripple due to commutation is analyzed and the practical method that can reduce the torque ripple is proposed. Experimental and simulation results show the effectiveness of the proposed method.

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