• 대한전기학회논문지
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• 제36권8호
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• pp.539-546
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• 1987

In case of operating at Variable speed the induction motor by a frequency transformer, it will cause ripples in motor torque and considerably bad effects on the machines because the output side of the frequency transformer involves a great number of harmonics. This paper Presents the methods of decreasing torque ripples in induction motor and of improving current waveform, by means of forming the waveforms of output current into multi-step waveforms similiar to sinusoid, and also by means of eliminating the harmonic components maximally, in case of operating a 18-phase multi-inverter combining 3-step current source inverter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.234-234
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• 2000

A direct torque control(DTC) based sensorless speed control system which employs a new closed loop flux observer is proposed. The flux observer takes an adaptive scheduling gains where motet speed is used as the scheduling variable. Adaptive nature comes from the fact that the estimated values of stator resistance and speed are included as observer parameters. The parameters of the PI controllers adopted in the adaptive law for the estimation of stator resistance and motor speed are determined by simple genetic algorithm. Simulation results in low speed region are given for comparison between proposed and conventional flux estimate scheme.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권2호
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• pp.162-167
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• 2005

This paper deals with the method of characteristic analysis of the capacitor-run single- phase induction motor having two poles (4-pole and 2-pole). This motor, which is referred to as a pole change motor in this paper, is capable of variable speed operation without inverters or drives. However, speed-torque curve can be distorted by the harmonic components contained in the magnetic flux density distribution. Therefore, the characteristics of this motor are analyzed using equivalent circuit considering harmonic components and the simulation results are compared with the experimental results.

• Journal of Power Electronics
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• 제18권4호
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• pp.1067-1074
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• 2018

This paper presents a control method for variable-speed motor drives that do not use a DC-link electrolytic capacitor. The proposed circuit consists of a power factor correction converter for boosting the DC-link voltage, an inverter for driving the motor, and a small DC-link film capacitor. By employing a small DC-link capacitor, the proposed circuit that is small, and a low cost and weight are achieved. However, because the DC-link voltage varies periodically, the control of the circuit is more difficult than that of the conventional method. Using the proposed control method, an inverter can be controlled reliably even when the capacitance of the DC-link capacitor is very small. Experiments are performed using a 1.5-kW inverter with a $20-{\mu}F$ DC-link capacitor, and the experimental results are analyzed thoroughly.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.516-523
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• 2013

This paper investigates an improved stator flux linkage observer for sensorless permanent magnet synchronous motor (PMSM) drives using a voltage-based flux linkage model and an adaptive sliding mode variable structure. We propose a new observer design that employs an improved sliding mode reaching law to achieve better estimation accuracy. The design includes two models and two adaptive estimating laws, and we illustrate that the design is stable using the Popov hyper-stability theory. Simulation and experimental results demonstrate that the proposed estimator accurately calculates the speed, the stator flux linkage, and the resistance while overcoming the shortcomings of traditional estimators.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.42-44
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• 2003

As the industry is developed, uses of various electric motor are increasing from general home to various fields of industry, and the kind becomes various daily. For these reasons, it is required to study the remote control and a package management about change of a speed drive system, the supervision of administration appliance by real time, and the collection and process data together using internet prevailed on industry whole. This paper deals with the development of a Web-Based remote control system for permanent magnet synchronous motor drives. The client/server system using TCP/IP protocols and DSP controller for remote control through internet and the Web interface that users can confirm data and state of PMSM(Permanent Magnet Synchronous Motor) is developed. This system is available for driving, braking, variable speed control and monitoring for PMSM in real time through administration program of Web-Based.

• 한국조명전기설비학회지:조명전기설비
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• 제9권4호
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• pp.62-70
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• 1995

Brushless DC Motor (BDCM) is widely used in the industry such as a variable speed motor in a compressor for room air conditioners, because the motor can be easily controlled and operated over a wide speed range. The system to drive BDCM needs encoder that senses rotor position. Gut in a certain application, the position sensor has to be avoided. In the paper, various position sensorless drive systems for BDCM are investigated and critically evaluated, so that the effective method of sensorless control can be selected. Out of these methods, the freewheeling diode current sensing has many advantages. For example, the simple starting procedure makes it possible to perform sensorless control even in low speed. So the hardware design for this method has been carried out and the system has been implemented using DSP. The experimental results verified that the freewheeling diode current sensing approach has advantages in starting procedure and low speed sensing.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1126-1129
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• 2000

The equivalent transformation of a brushless DC motor into an separately exited DC motor has been possible with the vector control technique. Vector control is an effective technique for controlling variable speed drives of brushless DC motors. Conventional vector controllers, however, suffer from electrical machine parameter variations because these controllers depend on the parameters. This paper presents the vector control of brushless DC motor using a neural network. In the proposed method, a neural network is employed as on-line estimator of the nonlinear dynamic equations of brushless DC motor. The neural network based vector controller has the advantage of robustness against machine parameter variations as compared with conventional vector controller The simulation results using Matlab/Simulink verify the useful of the proposed method.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1990년도 추계학술발표회논문집
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• pp.47-52
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• 1990

This paper presents a cyclocoverter with a LC resonant circuit for a induction motor dr-ive. The cycloconverter can provide variab-le voltage and frequency three phase output while keeping the input displacement factor at 1.0. The input current wave forms are sinusoidal, and the wide output frequency ran-ge is appropriate for variable speed AC motor drives.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권2호
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• pp.189-195
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• 2005

This paper presents a new velocity estimation strategy for a non-salient permanent magnet synchronous motor drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system, which contains the rotor position error information. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error at zero. For zero and low speed operation, the PI gain of the rotor position tracking controller has a variable structure according to the estimated rotor velocity. Then, at zero speed, the rotor position and velocity have sluggish dynamics because the varying gains are very low in this region. In order to boost the bandwidth of the PI controller during zero speed, the loop recovery technique is applied to the control system. The PI tuning formulas are also derived by analyzing this control system by frequency domain specifications such as phase margin and bandwidth assignment.