• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2117-2119
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• 1997

Several methods of induction motor drives, which use speed estimators instead of shaft encoders, have been reported. However, the sensorless field oriented control employing stator voltages and currents has difficulty in estimating rotor flux in the low-speed range. This paper investigates the rotor flux estimator which replace integrators with two lag circuits. The experimental results indicate good speed responses.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.487-492
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• 2000

This paper presents a novel method of slip-compensation for rotor time constant variation in indirect field orientation control of induction motor drives. In field oriented control due to variation of rotor time constant, decoupling between the flux and torque components of stator current is lost and hence, the performance of operation of the machine deteriorates. To solve the problem, the q-axis is aligned to reference frame without phase difference by comparing the real flux component with the reference flux component. Then to compensate the slip, PI controller is used. The proposed method keeps a constant slip by compensating the gain of direct slip frequency when the rotor resistance of induction motor varies. To prove the validations of the proposed algorithm in the paper, computer simulations and experiments are executed.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.208-215
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• 2007

The significant drawback of the permanent magnet linear synchronous motor (PMLSM) is force ripples, which are generated by the distortion of the stator flux linkage distributions, cogging forces caused by the interaction of the permanent magnet and the iron core and the end effects. This will deteriorate the performance of the drive system in high precision applications. The PMLSM and its parasitic effects are analyzed and modeled using the complex state-variable approach. To minimize the force ripple and realize the high precision control, the components of force ripples are extracted first and then compensated by injecting the instantaneous current to counteract the force ripples. And this method of the PMLSM system is realized by the field oriented control method. In order to verify the validity of this proposed method, the system simulations are carried out and the results are analyzed. The effectiveness of the proposed force ripples reduction method can be seen according to the comparison between the compensation and non-compensation cases.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.6
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• pp.567-573
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• 1991

Full direct digital control of induction motor driver is implemented with a minimal hardware structure. This paper deals with the presentation of a low-cost single-chip microprocessor-based control system for three-phase PWM generation and vector control that control speed of the induction motor using the field-oriented control method. Rotor flux is estimated using the indirect sensing method based on the rotor circuit equation in the synchronously rotation reference frame, and slip angle and rotor position are calculated from rotor angular velocity and stator current. Through simulation and experiment, it is shown that the proposed scheme gives good static and dynamic performance to the induction motor drive.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.466-469
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• 2001

In this paper, closed loop V/f control of induction motor has been implemented by the estimated speed. Closed loop V/f control improve the performance of induction motor drive system at low speed compared to open loop V/f control. However, closed loop V/f control need speed sensor. By using the estimated speed, closed loop V/f control is possible without speed sensor. Rotor speed is calculated from the difference between synchronous frequency and slip angular frequency. 3-phase voltage reference is obtained from synchronous frequency. And the PWM technique using space vector PWM is applied in this scheme. In the space vector PWM, effective time of 3-phase voltage reference is used to simplify the calculation of effective voltage time. This scheme is simple to implement and one chip microprocessor was used in experimental system.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.829-833
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• 2001

In a conventional speed sensorless stator flux­oriented (SFO) induction machine drive system, the estimated speed is delayed in transients by the use of a low pass filter. This paper investigates the problem of a conventional speed sensorless SFO system due to the delay of the estimated speed in the field weakening region. In addition, this paper proposes a method to estimate exactly speed by using Kalman filter. The proposed method is verified by simulation and experiment with a 5-hp induction motor drive.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.366-368
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• 1994

This paper deals with the vector control that control of torque and speed of the induction motor using field-oriented control method. Rotor flux is estimated using the indirect sensing method based on the rotor circuit equation in the synchronously rotation reference frame, and slip angle and rotor position are caculated from rotor angular velocity and stator current. Through modeling and digital simulation with a voltage source inverter, it is shown that the proposed scheme gives good static and dynamic performance to the induction motor drive.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.6
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• pp.531-536
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• 2002

This paper investigates the problem of the speed controller of conventional speed sensorless stator flux-oriented(SFO) induction motor drive, and proposes a robust speed controller to solve the conventional problem. In the proposed method, a robust speed controller for speed sensorless SFO system Is designed by taking advantage of disturbance torque observer and using feedforward.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1122_1123
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• 2009

Doubly Fed Induction Generator (DFIG) used in variable speed constant frequency wind energy generation system can capture wind energy with the highest efficiency by using the stator flux oriented vector control method. This paper sets up a DFIG modeling of wind generation system in PSCAD/EMTDC to simulate the operational performance with wind speed variation. In order to achieve the characteristics of the maximum utilization of wind power, this paper uses the vector control technology to track largest wind power and the independent control of generator active and reactive power.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.269-273
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• 2004

It is important to estimate the rotor speed for field weakening operation in the speed sensorless stator flux oriented (SFO) induction motor drive. Several methods have been reported to estimate exactly the speed in the speed sensorless system. In this paper, we apply two observer-based methods, the Luenberger observer (LO) and the Kalman filter (KF), to SFO induction motor drive in order to achieve a speed sensorless operation in field weakening region. Two control methods are reviewed and discussed. The operation characteristics of these methods in the field weakening region is compared by simulation and experiment.