• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.468-477
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• 2007

The DTC of voltage source inverter-fed PMSMs is based on hysteresis controllers of torque and flux. It has several advantages, namely, elimination of the mandatory rotor position sensor, less computation time, and rapid torque response. In addition, the stator resistance is the only parameter, which should be known, and no reference frame transformation is required. The DTC theory has achieved great success in the control of induction motors. However, for the control of PMSM drives proposed a few years ago, there are many basic theoretical problems that must be clarified. This paper describes an investigation into the effect of the zero voltage space vectors in the DTC system and points out that if using it rationally, not only can the DTC of the PMSM drive be driven successfully, but torque and flux ripples are reduced and overall performance of the system is improved. The implementation of DTC in PMSM drives is described and the switching tables specific for an interior PMSM are derived. The conventional eight voltage-vector switching table, which is namely used in the DTC of induction motors does not seem to regulate the torque and stator flux in a PMSM well when the motor operates at low speed. Modelling and simulation studies have both revealed that a six voltage-vector switching table is more appropriate for PMSM drives at low speed. In addition, the sources of difficulties, namely, the error in the detection of the initial rotor position, the variation of stator resistance, and the offsets in measurements are analysed and discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1685-1690
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• 2014

This paper proposes a novel method to compensate for the measurement errors in detecting phase currents for vector-controlled inverter in real-time. The output torque equations for 3-phase induction motor are derived in terms of offset error and transducing gain error in current measurement circuits, and the equations shows that motor output torque has many ripples due to current measurement errors. Especially, if the proposed method is applied to vector-controlled inverter, the torque ripple by transducing gain error can be reduced in real-time at running state of motor. To verify the proposed method, it was applied to vector-controlled inverter for 3-phase induction motor of 200[W] and computer simulation and experimentation were carried out.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.5
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• pp.352-359
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• 1987

The cycloconverter operating on a circulating current-free mode has many zero crossing points. If an exact zero crossing points are not detected, the three phase-unbalanced currents will flow in a motor. In this paper, the current feedback using a current reference wave is proposed to improve the problems of zero crossing detection, three phase-unbalanced voltages, currents, and torgue ripples. To prevent the saturation of the air gap flux and keep the torque constant, the constant voltage / hertz control with IR compensation is adopted. The PI-controller is designed using the linearized model of the cycloconverterinduction motor system. Alsi, Z-80A single board computer has been used to implement the proposed scheme which results in the performance improvement of cycloconterter-fed induction motor speed control system.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.568-572
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• 1991

This paper describes the three-phase inverter system for 1/2[HP] induction servo motor, using TMS370C050 single-chip microprocessor. The Power MOSFETs are used for PWM inverter circuit because of the advantages such as less harmonic losses and smaller peak current, less torque ripples and noises. Single-chip microprocessor enables the whole controller to be simple and reduced size as well as to more stable and flexible. The basic structures are shown for the power circuit, including the protection and driving circuitry, and the control loops for inverter control functions. The experimental results are given for the prototype PWM inverter system.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1336-1345
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• 2016

A modified space vector pulse width modulation (SVPWM) strategy based on vector space decomposition and its equivalent carrier-based PWM realization are proposed in this paper, which is suitable for six-phase asymmetrical dual stator induction machines (DSIMs). A DSIM is composed of two sets of symmetrical three-phase stator windings spatially shifted by 30 electrical degrees and a squirrel-cage type rotor. The proposed SVPWM technique can reduce torque ripples and suppress the harmonic currents flowing in the stator windings. Above all, the equivalent relationship between the proposed SVPWM technique and the carrier-based PWM technique has been demonstrated, which allows for easy implementation by a digital signal processor (DSP). Simulation and experimental results, carried out separately on a simulation system and a 3.0 kW DSIM prototype test bench, are presented and discussed.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.125-132
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• 2002

In this paper, a high performance current control strategy for a Brushless DC Motor is presented. The proposed strategy is based on the ramp comparison PI current control with the predictive voltage compensation. The proposed strategy is compared with the hysteresis current control strategy. The proposed method can improve the current waveforms, and it can reduce the torque ripples. So the proposed strategy is suitable to a high performance current control strategy for a Brushless DC Motor. The simulation and experimental results for a laboratory Brushless DC motor drive system confirm the validity of the proposed strategy.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1013-1014
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• 2007

This paper presents the design of Brushless DC (BLDC) motor using parametric design. According to the variation of magnitude of back emf and inductance, characteristic equations of BLDC motor are solved then output power, current, and torque ripples are calculated. Therefore output characteristics of BLDC motor according to motor parameter can be easily understood, and the range of back emf and inductance satisfying required output performance can be easily found. Presented design method leads to the BLDC motor design to be simple and effective, and the optimal design of BLDC motor using parametric design for 3kW with 50000rpm is presented.

• Journal of Magnetics
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• v.18 no.1
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• pp.50-56
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• 2013

In this paper, the 6-switch inverter for the Flux-Reversal Motor (FRM) has been presented and compared to the 4-switch inverter for the FRM, which is more popular in cost effective applications. To analyze the FRM, we adopted the two-dimensional time-stepped voltage source finite element method (FEM) that uses the actual pulse width modulation (PWM) voltage waveforms as the input data. As the FRM characteristic analysis of actual pwm voltage input, the torque ripples and iron losses (eddy current and hysteresis loss) of the FRM can be precisely calculated. With the simulated and experimental results, the performance and limitations of the 4-switch FRM which is the cost effective drive compared to the 6-switch FRM drive are provided in more detail.

• Journal of IKEEE
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• v.24 no.4
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• pp.1104-1108
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• 2020

This paper propose a variable proportional resonant feedforward algorithm for reducing the speed ripple of a three-phase permanent magnet synchronous motor. In general, the torque ripples can be generated by electrical pulsation due to current measurement errors and dead time and mechanical pulsation because of rotor eccentricity and eccentric load. These torque pulsations can cause speed pulsations of the motor and degrade the operating performance of the motor drive system. Therefore, in this paper, the factors of the speed ripple is analyzed and an algorithm to reduce the speed ripple is proposed. The proposed algorithm applied a variable proportional resonant controller in order to reduce the specific operating frequency included in the speed pulsation, and utilized a feedforward compensation controller structure to perform the compensation operation. The proposed algorithm is verified through various experiments.

• Journal of IKEEE
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• v.4 no.2 s.7
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• pp.225-232
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• 2000

Dead time which is inserted in PWM signals of VSI distorts the inverter output voltage waveforms and deteriorate the control performance of an induction machine by producing torque ripples. In this paper, dead time compensation method in a vector controlled induction machine is proposed. The method is based on a feedforward approach that compensates dead time effect by adding the compensating voltages to the inverter output voltage references in 2 phase stationary frame. The proposed method is only software intensive and easy to realize without additional hardware. The experimental results show the validity and effectiveness of the proposed method.