• Journal of Magnetics
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• 제17권2호
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• pp.109-114
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• 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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권3호
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• pp.93-100
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• 2003

Switched reluctance motor(SRM) has some advantages such as low cost, high torque density but SRM has essentially high torque ripple due to its salient structure. In order to apply SRM to industrial field, torque ripple has to be reduced. This paper introduces optimal design process of SRM using an optimization algorithm of Progressive Quadratic Response Surface Modeling(PQRSM) and two-dimensional(2D) Finite Element Method(FEM). The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, it can be obtained both the optimal design minimized torque ripple and the optima1 design maximized the average torque, respectively. Finally, this Paper Presents Performance comparison of two optimal designs and consider influence of the selected design variables in torque characteristics.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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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.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.39-46
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• 1998

For permanent magnet brushless DC motors used for high speed fuel pumps, torque ripple is an important origin of vibration, acoustic noise and speed fluctuation. In this paper, the output torque profile of a PM motor with one phase energized is decomposed into the commutation torque, the reluctance torque and the armature reaction torque according to their source origins. It verifies that the output torque profile is qualitatively equivalent to the BEMF profile for low reluctance motors. This paper discusses the effect of magnet pole shaping and magnet arc length on the output torque and torque ripple. A magnet edge shaping is proposed to design a trapezoidal BEMF motor without torque ripple, with minimal sacrifice of the maximum output torque.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.127-129
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• 1988

Square-wave current source inverter drives suffer from torque pulsation and speed variation at low speed. Attempts to minimize these problems, CSI PWM strategies have been reported. It is shown that these PWM strategies are based on unnecessarily restrictive modulation laws. In this paper, trapezoidal PWM strategy for CSI is investigated theoratically by double fourier series and we proposed Harmonic Speed ripple Factor(HSF) that is independent of motor parameters and load conditions. Speed ripple are considered in T-PWM and square wave inverter by HSF. We obtain modulation index(M) and carrier ratio (CR) for minimum speed ripple.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.347-349
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• 2013

This paper describes analysis and calculation of line frequency ripple current according to output capacitor value and effects of LED connection in the single stage flyback converter with high power factor. The low frequency output ripple current delivered from single stage converter has been analyzed in detail and the method evaluating parasitic resistance included in LED has been provided. In order to verify the equation derived in this paper, the single stage flyback converter has been designed with constant output current regulation with DCM operation. Experiments were conducted with different LED load structures to analyze the effect of LED parasitic resistance on output ripple current. As test results, the calculation can provide guide line to select capacitor values depending on output ripple current and LED characteristics.

• Journal of Power Electronics
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• 제16권5호
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• pp.1851-1860
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• 2016

The traction motors in electric multiple unit (EMU) trains are powered by AC-DC-AC converters, and the DC link voltage is generated by single phase PWM converters, with a fluctuation component under twice the frequency of the input catenary AC grid, which causes fluctuations in the motor torque and current. Traditionally, heavy and low-efficiency hardware LC resonant filters parallel in the DC side are adopted to reduce the ripple effect. In this paper, an analytical model of the ripple phenomenon is derived and analyzed in the frequency domain, and a ripple control scheme compensating the slip frequency of rotor vector control systems without a hardware filter is applied to reduce the torque and current ripple amplitude. Then a relatively simple discretization method is chosen to discretize the algorithm with a high discrete accuracy. Simulation and experimental results validate the proposed ripple control strategy.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.62-64
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• 2018

In two-stage single-phase inverters, inherent double line frequency component is present at both input and output of the front-end converter. Generally large electrolytic capacitors are required to eliminate the ripple. It is well known that the low frequency ripple shortens the lifespan of the capacitor hence the system reliability. However, the ripple can hardly be eliminated without the hardware combined with an energy storage device or a certain control algorithm. In this paper, a novel power-decoupling control method is proposed to eliminate the double line frequency ripple at the front-end converter of the DC/AC power conversion system. The proposed control algorithm is composed of two loop, ripple rejection loop and average voltage control loop and no extra hardware is required. In addition, it does not require any information from the phase-locked-loop (PLL) of the inverter and hence it is independent of the inverter control. In order to prove the validity and feasibility of the proposed algorithm a 5kW Dual Active Bridge DC/DC converter and a single-phase inverter are implemented, and experimental results are presented.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.349-349
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• 2000

A Clustering Adaptive Fuzzy Logic Controller(CAFLC) is applied to the torque control of a brushless do motor drive. Objective of this system includes elimination of torque ripple due to cogging at low speeds under loads. The CAFLC implemented has advantages of computational simplicity, and self-tuning characteristics. Simulation results showed that the torque ripple and dynamic response of the system using a CAFLC were superior to the model reference adaptive controlled system.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.106-112
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• 2012

As a fuel cell converts the chemical energy of the fuel cell into electrical energy by electrochemical reaction, the fuel cell system is uniquely integrated technique including fuel processor, fuel cell stack, power conditioning system. The residential fuel cell-PCS(Power Conditioning System) needs to convert efficiently the DC current produced by the fuel cell into AC current using single-phase DC-AC inverter. A single-phase DC-AC inverter has naturally low frequency ripple which is twice frequency of the output current. This low frequency(120Hz) ripple reduces the efficiency of the fuel cell. This paper presents notch filter with IP voltage controller to reject specific 120Hz current ripple in single-phase inverter. The notch filter is designed that suppress just only specific frequency component and no phase delay. Finally, the proposed notch filter design method has been verified with computer simulation and experimentation.