• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권2호
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• pp.47-53
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• 2004

The salient pole rotor type single phase SRM (switched reluctance motor) uses radial and axial direction magnetic flux simultaneously. Therefore, the output power per unit volume is very high and the shaft length is shorter than other types of SRMs with the same output. Furthermore, it can be manufactured with low cost owing to its simple structure and driving circuit. The prototype was designed using the theory of the traditional rotating machine and 3D FEM analysis. On this paper, the experiment apparatus, which includes the fabricated prototype in previous researches, was fabricated to measure the current and voltage of the prototype. Then the flux linkage, inductance and magnetic co-energy were calculated using the experimental results. Finally, the measured magnetic co-energy was compared with the simulated magnetic co-energy.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1614-1622
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• 2014

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DT-IPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

• Journal of Power Electronics
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• 제13권3호
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• pp.369-380
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• 2013

Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.264-267
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• 1989

In the vector controlled induction machine drives, mechanical speed sensors such as shaft encoder and resolver have been used. However, the mechanical speed sensors present some problems and restrict the wide applications of high performance AC drives. This paper describes the vector control strategy with the speed estimation algorithm in which motor slip frequency is calculated. Also, the angle deviation of the rotor flux vector is calculated and instaneously compensated to keep the q axis flux zero in the rotationary reference frame.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2057-2059
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• 2001

A nonlinear adaptive speed controller is designed for induction motors. Only the measurement of the stator current is used to design the controller and the observers. The sliding mode cascade observer is introduced to estimate the stator current and its time derivatives. The open-loop observer are designed to estimate the rotor flux and its time derivatives. The adaptive observer is also designed to estimate the rotor resistance. Sequentially, the rotor speed can be calculated using these estimated values. It is shown that the estimation errors of the corresponding states and the parameter converge to the specified residual set. It is also shown that the speed controller using these estimates is performed well. The experimental results are represented to investigate the validity of the proposed observer and controller.

• 전력전자학회논문지
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• 제17권3호
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• pp.238-245
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• 2012

This paper presents a sensorless speed control of a 2-phase switch reluctance motor(SRM). The proposed sensorless control scheme is based on the slide mode observer with parameter compensator to improve the estimation performance. In the stand still position, the initial rotor position is determined by pulse current responses of each phase windings and the current difference. In order to determine an accurate initial rotor position, the two initial rotor positions are estimated by the difference of the pulse currents. From the stand still to the operating region, a simple open loop control which determines the commutation sequence by the pulse current of the unexcited phase winding is used. When the motor speed is reached to the sensorless control region, the estimated rotor position and speed by the slide mode observer are used to control the SRM. The flux calculator used in the slide mode observer is designed by phase voltage and the voltage drops in the phase resistance of the winding. The accuracy of the flux calculator is dependent on the phase resistance. For the continuous update of the phase resistance, current gradient at the inductance break point is used in this paper. The error of the estimated rotor position at the current gradient position is used to update the phase resistance to improve the sensorless scheme. The proposed sensorless speed control scheme is verified with a practical compressor used in home appliances. And the results show the effectiveness of the proposed control scheme.

• Journal of Power Electronics
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• 제17권3호
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• pp.695-703
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• 2017

In order to satisfy the urgent requirements for the overheating protection of induction motors, an approach that can be used to identify motor temperature has been proposed based on the rotor slots harmonic (RSH) in this paper. One method to accomplish this is to improve the calculation efficiency of the RSH by predicting the stator winding distribution harmonic order by analyzing the harmonics spectrum. Another approach is to increase the identification accuracy of the RSH by suppressing the influence of voltage flashes or current surges during temperature estimation based on model predictive control (MPC). First, an analytical expression of the stator inductance is extracted from a steady-state positive sequence motor equivalent circuit model developed from the rotor flux field orientation. Then a procedure that applies MPC for reducing the identification error of the rotor temperature caused by voltage sag or swell of the power system is given. Due to this work, the efficiency and accuracy of the RSH have been significantly improved and validated our experiments. This work can serves as a reference for the on-line temperature monitoring and overheating protection of an induction motor.

• 전기학회논문지
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• 제60권5호
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• pp.942-948
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• 2011

This paper deals with characteristic analysis of axial flux permanent magnet (AFPM) machines with axially magnetized PM rotor using quasi-3-D analysis modeling. On the basis of magnetic vector potential and a two-dimensional (2-D) polar-coordinate system, the magnetic field solutions due to various PM rotors are obtained. In particular, 3-D problem, that is, the reduction of magnetic fields near outer and inner radius of the PM is solved by introducing a special function for radial position. And then, the analytical solutions for back-emf and torque are also derived from magnetic field solutions. The predictions are shown in good agreement with those obtained from 3-D finite element analyses (FEA). Finally, it can be judged that analytical solutions for electromagnetic quantities presented in this paper are very useful for the AFPM machines in terms of following items : initial design, sensitivity analysis with design parameters, and estimation of control parameters.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.304-307
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• 2002

A sensorless velocity control strategy for permanent magnet synchronous motors is presented in this paper. Two stator currents are measured and processed in discrete form in DSP. The rotor position and speed are estimated through the stator flux linkage and its derivative estimation. Flux and its derivative are calculated in the stationary reference frame and used to estimate the speed and position. The closed-loop speed control has been shown to be effective from standstill to rated speed. Moreover, a flux drift problem caused by the integration can be eliminated so that a stable sensorless starting and running operation can be achieved. Experimental results are presented to demonstrate the effectiveness of the proposed scheme.

• 한국항행학회논문지
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• 제17권3호
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• pp.332-345
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• 2013

본 논문에서는 최근, 압전 변압기 기술의 급속한 발전을 이용하므로 자계의 잡음이 없고, 크기가 소형화되며 고효율과 고 전력 밀도, 누설자속이 없어 노이즈 발생이 없고, 공진주파수만을 이용하므로 출력파형이 정현파에 가까워 고조파 잡음이 없는 점을 이용하여 전기적인 등가회로를 적용하여 DC-DC 컨버터를 구현 하였다. 유도전동기 회전자 속도 개념에 자속 기준 모델 적용 시스템(FMRAS)을 적용하였다. 유도전동기의 벡터제어는 회전자 속도 정의의 추정값을 이용하여 실행 할 수 있고, 부가된 변화되는 모델로 회전자 목표값 계산을 수행 할 수 있다. 이 시스템은 PWM 공간 전압기법과 DC-DC 컨버터를 이용하여 벡터전류제어와 속도제어를 위한 PI제어기로 구성되어 있다. 제어를 위한 실행과 높은 속도계산을 디지털 신호 원칩 마이크로프로세서에 의해 수행 되었고, 시뮬레이션과 실험을 통해서 다양한 제어 방법의 타당성을 제시 하였다.