• 전력전자학회논문지
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• 제19권3호
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• pp.249-256
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• 2014

This paper proposes a torque control method of permanent magnet synchronous motor, which has small torque ripple. The proposed control method is using the finite control set-model predictive control(FCS-MPC) strategy. An optimal input voltage vector minimizing a cost function is chosen among 6 passible active input voltage vectors following the FCS-MPC strategy. Then, a modulation factor for the optimal input voltage vector is computed to minimize the torque ripple. Thus, the proposed control method yields fast torque response and small torque ripple. The efficacy of the proposed method was verified through simulation and experiment.

• Journal of Power Electronics
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• 제5권4호
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• pp.264-271
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• 2005

A new modified trapezoidal modulating signal for a pulse width modulation (PWM) inverter suitable for a permanent magnet synchronous motor (PMSM) drive is proposed in this paper. A new modulating signal for the PMSM drive is determined by the characteristic torque ripple of the motor with various electro-motive force (EMF). The proposed modulating signal is able to decrease the torque ripple even if the motor has sinusoidal EMF or non-sinusoidal EMF. By using the proposed modulating signal, the system reduced the torque ripple as well as achieved the effective utilization of the DC supply voltage for the inverter. Many improvements are accomplished by the PWM strategy adapting the modified trapezoidal modulating signal without a change in hardware.

• 전력전자학회논문지
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• 제28권1호
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• pp.59-67
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• 2023

This paper explores the variation of DC-Link current ripple analysis in terms of duty cycle and phase angle of Multi-phase/Multi-stage boost converter. A 2-Stage/1-Stage boost converter DC-Link current is used to determine the difference between the 1st stage diode current and the 2nd stage inductor current. Each stage boost converter diode and inductor current is subordinate to the phase angle and duty cycle. The magnitude of the ripple current is variable according to phase angle and duty cycle. The analysis results are verified by variation of DC-Link current ripple using a 1kW typical 2-stage/1-stage boost converter.

• 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.

• Journal of Power Electronics
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• 제9권4호
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• pp.623-630
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• 2009

This paper proposes a filter design guideline for grid-connected single-phase inverters. By analyzing the instantaneous voltage applied to the filter inductor, the switching ripple current through the filter inductor can be precisely calculated. Therefore, filter inductance can be designed accurately, which guaranties that the switching ripple current will be under the target value. The proposed filter design method is verified by experiment.

• 전기학회논문지
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• 제58권10호
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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).

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권8호
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• pp.389-395
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• 2006

In the single-phase switched reluctance motor (SRM) drive, the required DC source is generally supplied by the circuit consisting of bridge rectifier with diodes and many filter capacitances connected with AC source. Although the peak torque ripple of SRM is small because of large capacity of the capacitance, the charge and discharge time swhich the AC source acts on the capacitance are small and the peak current will pass on the side of source, so power factor and system efficiency decrease. Therefore a novel SRM drive system is presented in this paper, which includes drive circuit realizing reduction of torque ripple and improvement of power factor and switching topology. The proposed drive circuit consists of one switching part and diodes which can separate the output of AC/DC rectifier from the large capacitance and supply power to SRM alternately in order to realize reduction of torque ripple and improvement of power factor through the turn on and turn off of switching part. In addition, the validity of method is tested by simulation and experiment.

• Journal of Power Electronics
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• 제13권3호
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• pp.339-348
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• 2013

Multiphase dc-dc converters are widely used in modern power electronics applications due to their advantages over single-phase converters. Such advantages include reduced current stress in both the switching devices and passive elements, reduced output current ripple, and so on. Although the output current ripple of a converter can be significantly reduced by virtue of the interleaving effect, the inductor current ripple cannot be reduced even with the interleaving PWM method. One way to solve this problem is to use a coupled inductor. However, care must be taken in designing the coupled inductor to maximize its performances. In this paper, a detailed analysis of a coupled inductor is conducted and the effect of a coupled inductor on current ripple reduction is investigated extensively. From this analysis, a UU core based coupled inductor structure is proposed to maximize the performance of the coupled inductor.

• Journal of Power Electronics
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• 제10권6호
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• pp.709-716
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• 2010

MDPS (motor driven power steering) systems have been widely used in vehicles due to their improved fuel efficiency and steering performance when compared to conventional hydraulic steering. However, the reduction of torque ripples and material cost are important issues. A low resolution position sensor for MDPS is one of the candidates for reducing the material costs. However, it may increases the torque ripple due to the current harmonics caused by low resolution encoder signals. In this paper, the torque ripple caused by the quantized rotor position of the low resolution encoder is analyzed. To reduce the torque ripples caused by the quantization of the encoder signals, the rotor position and the speed are estimated by measuring the frequency of the encoder signals. In addition, the compensating q-axis current is added to the current command so that the 6th order torque harmonic is attenuated. The reduction of torque ripples by applying the estimated rotor position and the compensated q-axis current is verified through experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.57-61
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• 2006

In the single-phase switched reluctance motor (SRM) drive, the required DC source is generally supplied by the circuit consisting of bridge rectifier and large filter capacitor connected with DC line terminal. Due to the large capacity of the capacitor, the charged time of capacitor is very short from the AC source. Lead to the bridge rectifiers draws pulsating current from the AC source side, which results in reduction of power factor and low system efficiency. Therefore a novel single-phase SRM drive system is presented in this paper, which includes drive circuit realizing reduction of torque ripple and improvement of power factor with a novel switching topology. The proposed drive circuit consists of one switching part and diode, which can separate the output of AC/DC rectifier from the large capacitor and supply power to SRM alternately, in order to realize the torque ripple reduction and power factor improvement through the switching scheme. In addition, the validity of the proposed method is tested by some simulations and experiments.