• 전기학회논문지P
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• 제53권4호
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• pp.195-200
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• 2004

Many kinds of speed sensorless control system of induction motor had been developed. But it is difficult to implement at the real system because of complex algorithm and equations. This paper investigates a novel speed sensorless control of induction motor using neural networks. The proposed control strategy is based on neural networks using stator current and output of neural model based on state observer. The errors between the stator current and the output of neural model are back-propagated to adjust the rotor speed, so that adaptive state variable will coincide with the desired state variable. This algorithm may overcome several shortages of conventional model, such as integrator problems, small EMF at low speed and relatively large sensitivity of stator resistance variation. Also, this paper presents a newly developed optimal equation about the momentum constant and the learning rate. The proposed algorithms are verified through simulation.

• Journal of Power Electronics
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• 제6권1호
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• pp.52-66
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• 2006

This paper proposes a wind energy conversion system connected to a grid using a self-excited induction generator (SEIG) based on the maximum power point tracking (MPPT) control scheme. The induction generator (IG) is controlled by the MPPT below the base speed and the maximum energy can be captured from the wind turbine. Therefore, the stator currents of the IG are optimally controlled using the indirect field orientation control (IFOC) according to the generator speed in order to maximize the generated power from the wind turbine. The SEIG feeds a (CRPWM) converter which regulates the DC-link voltage at a constant value where the speed of the IG is varied. Based on the IG d-q axes dynamic model in the synchronous reference frame at field orientation, high-performance synchronous current controllers with satisfactory performance are designed and analyzed. Utilizing these current controllers and IFOC, a fast dynamic response and low current harmonic distortion are attained. The regulated DC-link voltage feeds a grid connected CRPWM inverter. By using the virtual flux orientation control and the synchronous frame current regulators for the grid connected CRPWM inverter, a fast current response, low harmonic distortion and unity power factor are achieved. The complete system has been simulated with different wind velocities. The simulation results are presented to illustrate the effectiveness of the proposed MPPT control scheme for a wind energy system. In the simulation results, the d-q axes current controllers and DC-link voltage controller give prominent dynamic response in command tracking and load regulation characteristics.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.417-420
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• 2000

In order to the torque control the indirect flux control was performed by controlling the ratio of e/f and the q-axis flux was estimated by the slip command and q-axis flux was estimated by the slip command and q-axis current in the rotor circuits. Also the frequency was controlled to keep on the q-axis flux to be zero and the constant torque characteristics could be obtained by generation the preset torque. In the induction motor driven by the boltage source inverter with the constant voltage and frequency the speed variation is expressed as a slip So the speed control can be achieved by slip compensation The slip was calculated with a q-flux current filtered by first-order filter and as the result the error problem which may occur in current detection was eliminated

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권7호
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• pp.337-345
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• 2006

This paper proposes a high speed SRM drive system for blower application with a new 4-level inverter and precise excitation position generator. For a high speed blower, a proper inverter and control method are proposed and the output characteristics are analyzed. In order to get a fast build-up and demagnetization of excitation current, a 4-level inverter system is proposed. The proposed 4-level inverter has additional charge capacitor, power switch and diode in the conventional asymmetric converter. The charged high voltage is supplied to the phase winding for fast current build-up, and demagnetization current is charged to additional capacitor of the 4-level inverter. In addition, a precise excitation position generator can reduce turn-on and turn-off angle error according to sampling period of digital control system. The proposed high speed SRM drive system is verified by computer simulation and experimental results.

• 전력전자학회논문지
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• 제20권5호
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• pp.429-436
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• 2015

Torque ripples generate mechanical vibration at low speed and acoustic noise at high speed. The back emf harmonics of a PM synchronous motor is one of the main sources of torque ripples. To reduce torque ripples resulting from back emf harmonics, dq-axis harmonic currents that reduce the torque ripples are generally compensated to the current controller. Harmonic current compensation is effective at low speed, but it is not applicable at high speed because of the limited bandwidth of the current controller. In this study, dq-axis harmonic voltage compensation that can reduce torque ripples at high speed is proposed. The dq-axis harmonic voltages are calculated from the motor speed and the dq-axis harmonic currents. The effectiveness of the proposed method in reducing torque ripple is verified by a simulation and experiments.

• 반도체디스플레이기술학회지
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• 제14권2호
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• pp.35-40
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• 2015

This paper presents the sensorless position control of the Permanent Magnet Synchronous Motor (PMSM) using stator flux estimation and Phase Lock Loop (PLL). The field current and the torque current are required in order to perform the vector control of the PMSM. At this time, it is necessary for the torque to know the exact position of the magnetic flux generated by the permanent magnet, because the torque must be applied torque current in the direction orthogonal to the permanent magnet. In general the speed of the PMSM is controlled by using a magnetic position sensor. However, this paper, we estimates the stator flux by using the PLL method without the magnetic position sensor. This method is simple and easy, in addition it has the advantage of a stabile estimation of the rotor. Finally the proposed algorithm was confirmed by experimental results and showed the good performance.

• 전기학회논문지P
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• 제52권1호
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• pp.1-8
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• 2003

The paper proposes instantaneous torque control of IPMSM for maximum torque drive of torque and current plane. The control scheme is based on the mathematical model of the motor and is applicable to the constant torque and field weakening operations. The scheme allows the motor to be driven with maximum torque per ampere(MTPA) characteristic below base speed and it maintains the maximum voltage limit of the motor wide field weakening and the motor current limit under all conditions of operation accurately. For each control mode, a condition that determines the optimal d-axis current $^id$ for maximum torque operation is derived. The proposed control algorithm is applied to IPMSM drive system for drive of wide speed range, the operating characteristics controlled that maximum torque control are examined in detail by simulation.

• 전력전자학회논문지
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• 제8권1호
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• pp.56-63
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• 2003

본 연구에서는 감쇠상 역기전력을 고려한 토크모델이 도통 및 전환구간에서 다름을 보였으며 이를 통해 전환구간에서 나타나는 토크맥동을 수학적으로 해석하였다. 본 논문에서는 전환시간에 의해 나타나는 토크맥동을 저감할 수 있는 새로운 방식을 제안하였다. 첫째, 전환시간을 조절하여 상승상 및 감쇠상의 전류의 기울기를 일정하게 조정하는 절환지연시간제어를 제안하였다. 이를 통하여 비전환상에서의 전류맥동을 저감하였으며 직류단전압과 4배의 역기전력전압의 크기가 같아지는 임계속도 이하에서 토크맥동을 저감할 수 있다. 그러나, 역기전력 및 전환하는 전류의 관계에 의해 토크맥동이 여전히 존재한다. 특히 임계속도 이상에서는 토크맥동율이 크게 증가한다. 둘째, 역기전력과 전류의 관계에 따라 나타나는 토크맥동을 고려한 전환시점제어를 제안하였다. 제안한 방식에 의하여 BLDC 전동기의 토크맥동을 임계속도 이상에서 뿐 만 아니라 전 속도영역에서도 최소화 할 수 있다.

• 전기학회논문지P
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• 제61권4호
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• pp.206-213
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• 2012

This paper propose a improved speed control system for five-phase squirrel-cage induction motor(IM) considering effects of 3rd. harmonic current components with field oriented control(FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[KW] induction motor.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1048-1057
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• 2015

This paper proposes a sensorless speed control algorithm for parallel-connected dual Surface-mounted Permanent Magnet Synchronous Motors (SPMSMs) fed by a single inverter. For stable parallel operation of synchronous motors with a single inverter, each motor has to be constantly kept in the synchronization state regardless of load torque. If the master motor with the larger load is controlled, the synchronous state will be maintained. Therefore, detection of the master motor is essential. Conventionally, the master motor is determined by comparing the rotor position error from the relation between the back-EMF for torque angle and the flux position; consequently, the position sensor is deemed essential for finding the rotor position. The parallel sensorless speed control method proposed in this paper uses no position sensor, instead it compares the flux-axis current from the connection between the back-EMF for torque angle and current in unbalanced load conditions. The results of simulation and experiment conducted verify the efficacy of the proposed method.