• 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.

• Journal of Power Electronics
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• v.2 no.3
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• pp.220-229
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• 2002

In this paper, maximum efficiency operation of two types of permanent magnet synchronous motor drives, namely; surface type permanent magnet synchronous machine (SPMSM) and interior type permanent magnet synchronous motor(IPMSM), are investigated. The efficiency of both drives is maximized by minimizing copper and iron losses. Loss minimization is implemented using flux weakening. A neural network controller (NNC) is designed for each drive, to achieve loss minimization at difffrent speeds and load torque values. Data for training the NNC are obtained through off-line simulations of SPMSM and IPMSM at difffrent operating conditions. Accuracy and fast response of each NNC is proved by applying sudden changes in speed and load and tracking the UC output. The drives'efHciency obtained by flux weakening is compared with the efficiency obtained when setting the d-axis current component to zero, while varying the angle of advance "$\vartheta$" of the PWM inverter supplying the PMSM drive. Equal efficiencies are obtained at diffErent values of $\vartheta$, derived to be function of speed and load torque. A NN is also designed, and trained to vary $\vartheta$ following the derived control law. The accuracy and fast response of the NN controller is also proved.so proved.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.774-779
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• 1998

For the speed control of motors, the position or speed sensors are necessary to obtain the position information of the rotor. Specially, SRM(Switched Reluctance Motor) needs an accurate rotor position data because both the rotor and the stator have a salient pole structure. High functional sensors like resolver or encoder are expensive and have complex connecting lines to the controller so the pure signals are apt to be mixed with noised. In the sight of SRM drives, the high temperature, heavy dust, and the EMI surroundings reduce the reliability of speed and position sensors. Therefore, the speed and position sensorless control algorithms using observer have been accepted widely. In this paper An adaptive sliding observer is described to control the SRM without speed or position sensors. The adaptive sliding observer is set on the basis of variable structure control theory. The sliding surface is constructed by current error terms and this surface guarantees the errors converge to "zero". The stability of observer is affirmed by Lyapunov stability analysis and popov's hyper stability theory.ty theory.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.435-438
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• 2002

The Objects of this paper are developing and also improving a high-speed driving system of bushless DC motor(BLDCM) with economical and practical performance. Because BLDC motors are manufactured that each motor can create proper torque for their individual purpose, it is difficult to increase over the rated speed when a motor speed (with it's rated road) is reaching to a maximum speed so the motor torque cannot be increased. This paper verifies the effects of Leading Angle Algorithm, that is proposed on this paper, with examining existing methods to maximize the torque of a motor in high-speed driving area. The arithmetic processor for this experiment is TMS320C240 DSP controller that is designed for a special purpose of motor control in Texis Instrument Inc., and the used Inverter is PM10CSJ060, a Intelligent Power Module of Mitsubishi Corporation.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.681-685
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• 2003

In this paper, an sensing method of initial rotor position in Switched Reluctance Motor(SRM) at standstill is proposed. In case search coils are used as a position sensor, A search coil used in a method of detecting positions of TSRM has many advantages, which is highly efficient in low cost and maintenance free, and characterized by its function and role as a position sensor. However, the initial rotor position detection is very difficult because the search coil's EMF is not exist at a standstill. In this paper, a new sensing method of initial rotor position using squared Euclidean distance at a standstill too is suggested. The simulation and experiment for the proposed method are achieved. The validity of the proposed method is verified by experimental results.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1773-1780
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• 2016

This paper proposes a wide air-gap control method for the multi-module permanent magnet linear synchronous motor (MM-PMLSM) based on independent vector control. In particular, the MM-PMLSM consists of symmetrical multi-module and multi-phase structures, which are basically three-phase configurations without a neutral point, unlike conventional three-phase machines. In addition, there are no additional magnetic levitation windings to control the normal force of the air-gap between each stator and mover. Hence, in this paper, a dq-axis current control applying a d-q transformation and an independent vector control are proposed for the air-gap control between the two symmetric stators and mover of the MM-PMLSM. The characteristics and control performance of the MM-PMLSM are analyzed under the concept of vector control. As a result, the proposed method is easily implemented without additional windings to control the air-gap and the mover position. The effectiveness of the proposed independent vector control algorithm is verified through experimental results.

• Journal of Power Electronics
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• v.16 no.5
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1546-1551
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• 2008

This paper is concerned with the problems of accurate losses segregation in capacitor-run single phase motor. Segregation of losses in single phase induction motor is more complicated than that in three phase induction motor, because of the backward magnetic field component in the motor. Generally there are two methods for losses segregation of single phase induction motor. The one is relatively complicated method based on parameter estimation of single phase induction motor. By the way, the other one is simplified method based on IEEE Standard 114. All of the methods for the experimental determination of single phase induction motor losses are studied in this paper. Since the IEEE Standard is not possible to be applied for all type of single phase induction motors, we modified that method to apply for losses segregation of capacitor-run single phase induction motor as unifying the method based on parameter estimation.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.451-461
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• 2010

Electric vehicles (EVs) require fast torque response and high drive efficiency. This paper describes a control scheme of fuzzy direct torque control of permanent magnet synchronous motor for EVs. This control strategy is extensively used in EV application. With direct torque control (DTC), the electromagnetic torque and stator flux can be estimated using the measured stator voltages and currents. The estimation depends on motor parameters, except for the stator resistance. The variation of stator resistance due to changes in temperature or frequency downgrades the performance of DTC, which is controlled by introducing errors in the estimated flux linkage vector and the electromagnetic torque. Thus, compensation for the effect of stator resistance variation becomes necessary. This work proposes the estimation of the stator resistance and its compensation using a proportional-integral estimation method. An electronic differential has been also used, which has the advantage of replacing loose, heavy, and inefficient mechanical transmission and mechanical differential with a more efficient, light, and small electric motors that are directly coupled to the wheels through a single gear or an in-wheel motor.

• Journal of Power Electronics
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• v.8 no.4
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• pp.301-308
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• 2008

This paper proposes a method of improving the stability in sensor-less control of permanent magnet synchronous motors. The control method for low-speed region is divided into two: One is a high frequency method, which involves a problem of reverse rotation once misdetection of the permanent magnet polarity should occur, and another one is a current drive method, which has a problem that phase and speed oscillations are caused by quick speed changes. Hence, authors propose adoption of the current drive method for the basic control system with added compensation of stabilization by means of the high frequency method. This combination secures stable control with no risk of reversal and less vibration. In addition, authors have also considered a frequency separation filter of a shorter delay time so that current control performance will not lower even when high frequencies are introduced. This filter has achieved simplified compensation using repetitive characteristic through the utilization of the periodicity of high frequency current. Simulation and experiment have been conducted to verify that the stable performance of this system is improved.