• Title, Summary, Keyword: Torque ripple reduction

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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).

Optimum Rotor Shaping for Torque Improvement of Double Stator Switched Reluctance Motor

  • Tavakkoli, Mohammadali;Moallem, Mehdi
    • Journal of Electrical Engineering and Technology
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    • v.9 no.4
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    • pp.1315-1323
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    • 2014
  • Although the power density in Double Stator Switched Reluctance Motor (DSSRM) has been improved, the torque ripple is still very high. So, it is important to reduce the torque ripple for specific applications such as Electric Vehicles (EVs). In This paper, an effective rotor shaping optimization technique for torque ripple reduction of DSSRM is presented. This method leads to the lower torque pulsation without significant reduction in the average torque. The method is based on shape optimization of the rotor using Finite Element Method and Taguchi's optimization method for rotor reshaping for redistribution of the flux so that the phase inductance profile has smoother variation as the rotor poles move into alignment with excited stator poles. To check on new design robustness, mechanical analysis was used to evaluate structural conformity against local electromagnetic forces which cause vibration and deformation. The results show that this shape optimization technique has profound effect on the torque ripple reduction.

Torque Ripple Reduction in Direct Torque Control of Five-Phase Induction Motor Using Fuzzy Controller with Optimized Voltage Vector Selection Strategy

  • Shin, Hye Ung;Kang, Seong Yun;Lee, Kyo-Beum
    • 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.

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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Torque ripple reduction in DTC of induction motor driven by 3-level inverter (3레벨 인버터로 구동되는 유도전동기 직접토크제어의 토크리플 저감법)

  • Lee, Kyo-Beum;Song, Joong-Ho;Choy, Ick;Yoo, Ji-Yoon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.5 no.6
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    • pp.620-631
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    • 2000
  • A torque ripple reduction technique of direct torque control(DTC) for high power induction motors driven by 3-level inverters with the inverter switching frequency limited around 0.5-1.0kHz level is presented. It is noted that conventional DTC algorithms to reduce torque ripple are devised for applications with relatively high switching frequency above 2-3kHz. Such conventional algorithms can not accomplish satisfactory torque ripple reduction for 3-level inverter systems with lower switching frequency. A new DTC algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over the operating speed region. Simulation and experimental results show the effectiveness of the proposed control algorithm.

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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.

A Study on the Torque Ripple Reduction of Low Voltage High Current SPMSM (저전압 대전류 SPMSM 토크리플 저감 제어)

  • Lee, Geun-Ho;Hong, Jeong-Pyo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.12
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    • pp.2391-2395
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    • 2009
  • Active control schemes which modify the excitation to correct for any of the nonideal characteristics of the SPMSM is described. Especially, because of design limitations(size and cost) in automobile, the back-EMF of SPMSM can't be perfectly designed with sinusoidal wave and iron core of stator is saturated so that torque ripple is unavoidable. An active cancellation method of the pulsating torque components which would otherwise be generated using the classic sinusoidal current excitation is illustrated.

Extending Switching Frequency for Torque Ripple Reduction Utilizing a Constant Frequency Torque Controller in DTC of Induction Motors

  • Jidin, Auzani;Idris, Nik Rumzi Nik;Yatim, Abdul Halim Mohd;Sutikno, Tole;Elbuluk, Malik E.
    • Journal of Power Electronics
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    • v.11 no.2
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    • pp.148-155
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    • 2011
  • Direct torque control(DTC) of induction machines is known to offer fast instantaneous torque and flux control with a simple control structure. However, this scheme has two major disadvantageous, namely, a variable inverter switching frequency and a high torque ripple. These problems occur due to the use of hysteresis comparators in conventional DTC schemes, particularly in controlling the output torque. This paper reviews the utilization of constant frequency torque controllers (CFTC) in DTC to solve these problems while retaining the simple control structure of DTC. Some extensions of the work in utilizing a CFTC will be carried out in this paper which can further reduce the torque ripple. This is particularly useful for a system which has a limited/low sampling frequency. The feasibility of a CFTC with an extended carrier frequency in minimizing the torque ripple is verified through experimental results.

Torque Ripple Reduction of an Interior PM Synchronous Motor by Compensating Harmonic Currents Based on Flux Linkage Harmonics

  • Nam, Myung Joon;Kim, Jong Hyun;Cho, Kwan-Yuhl;Kim, Hag-Wone;Cho, Younghoon
    • Journal of Power Electronics
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    • v.17 no.5
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    • pp.1223-1230
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    • 2017
  • The back emf harmonics of a permanent magnet (PM) synchronous motor is a major source of torque ripple. For torque control applications including column fitted MDPS (motor driven power steering) systems, it is essential to reduce the mechanical vibrations due to torque ripples at low speeds. In this paper, a torque ripple reduction algorithm for interior PM synchronous motors is proposed. The harmonic currents that cancel the $6^{th}$ order torque harmonic are added to the nominal dq currents for MTPA (maximum torque per ampere) operation. The compensated harmonic currents are derived from flux linkage harmonics based on a FFT analysis of the back emf harmonics. Simulation and experimental results verify that the $6^{th}$ order torque harmonic and THD of the torque ripple are reduced by compensating the dq harmonic currents.

Torque Ripple Minimization for IPMSM with Non Sinusoidal Back-EMF (비정현적인 역기전력을 가진 매입형 영구자석 동기전동기의 토크리플 저감에 관한 연구)

  • 이상훈;홍인표;박성준;김철우
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.1
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    • pp.91-100
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    • 2002
  • This paper deals with the ripple reduction of the electromagnetic torque developed in IPMSM(Interior Permanent Magnet Synchronous Motor). Generally, torque ripple is an important causes of vibration and noise of motor. For reducing torque ripple in IPM with nonsinusoidal EMF, the optimal current which is able to control maximum torque/ampere is considered to be introduced In the proposed method. The fact of torque ripple being reduced when the optimal current Is used in motor is verified through simulation and experiment.