• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.7
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• pp.494-499
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• 2000

In a conventional stator flux-oriented(SFO) induction machine drive system, the field weakening method is to vary flux reference in proportion to the inverse of the rotor speed. This paper investigates that maximum torque capability cannot be obtained in the conventional system and proposes a new selection method of flux reference to obtain maximum torque capability over the field weakening region by considering voltage, torque, and current limits.

• Journal of Power Electronics
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• v.3 no.2
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• pp.115-123
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• 2003

This paper presents analysis, design and simulation for the indirect field orientation control (IFOC) of induction machine drive system. The dynamic performance of the IFOC under nominal and detuned parameters of the induction machine is established. A conventional proportional plus integral-derivative (PI-D) two-degree-of-freedom controller (2DOFC) is designed and analysed for an ideal IFOC induction machine drive at nominal parameters with the desired dynamic response. Varying the induction machine parameters causes a degredation in the dynamic response for disturbance rejection and tracking performance with PI-D 2DOF speed controller. Therefore, conventional controllers can nut meet a wide range of speed tracking performance under parameter variations. To achieve high- dynamic performance, a proposed robust fuzzy logic controllers (RFLC) for d-axis rotor flux, d-q axis stator currents and rotor speed have been designed and analysed. These controllers provide robust tracking and disturbance rejection performance when detuning occurres and improve the dynamic behavior. The proposed REL controllers provide a fast and accurate dynamic response in tracking and disturbance rejection characteristics under parameter variations. Computer simulation results demonstrate the effectiveness of the proposed REL controllers and a robust performance is obtained fur IFOC induction machine drive system.

• 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.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.109-111
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• 1997

A sensorless drive of induction motor has several advantages; low cost and mechanical simplicity. This paper investigates a field-oriented control method without speed and flux sensors. The control strategy is to design an adaptive state observer for flux estimation and to estimate the rotor speed from the estimated rotor flux and stator current. The entire control algorithm including space vector PWM is implemented by software of the digital signal processor TMS320C31. The experimental results indicate good speed responses.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.5
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• pp.338-344
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• 2000

This paper proposes a field-oriented control strategy without speed sensor in overall speed range. At low speed region including zero speed, the electrical saliency which is due to the main flux saturation is used in order to estimate an instantaneous flux position. This electrical saliency can be obtained from the difference of high frequency impedance by the high frequency signal injection. This method enables the stable operation at zero speed or stator frequency even under heavily loaded condition. However, because of the high frequency signal injection the loss and noise in motor increase and the voltage margin is reduced as the motor speed increases. Therefore, this algorithm must be supplemented with the algorithm based on the electrical model of motor, which is conventionally used in the region except the low speed. This paper proposes the combination algorithm between the high frequency signal infection method and the adaptive observer, in which the rotor flux and motor speed can be simultaneously estimated by the adaptive control theory. This combination algorithm enables the stable operation of field-oriented speed control without speed sensor in overall speed range. This is verified by experimental results.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.248-252
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• 2003

This paper has a control method proposed for the effective self-tuning fuzzy speed control based on neural network of the induction motor indirect vector control. The vector control of an induction motor provides the decoupled control of the rotor flux magnitude and the torque producing current to performance is desirable. But, the drive performance often degrades for the machine parameter variations and its condition give rise to coupling of flux and torque current. The fuzzy speed control of an induction motor has the robustness about machine parameter variations compared with conventional PID speed control in a way. That proved to be some waf from the true. The purpose of this paper is to improve the adaptation by offering self-turning function to fuzzy speed controller. In this paper, the adaptive mechanism of fuzzy speed control in used ANN(Artificial Neural Network) technique is applied in an IFO induction machine drive, such that the machine can follow a reference model (an ideal field oriented machine) to achieve desired speed. In this paper proved the self-turning method of fuzzy controller has the robustness about parameter variation and the wide range of adaptation by simulation.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.616-621
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• 2004

This paper investigated the speed sensorless indirect vector control of a two-phase induction motor to implement adjustable-speed drive for low-power applications. The sliding mode observer estimates rotor speed. The convergence of the nonlinear time-varying observer along with the asymptotic stability of the controller was analyzed. To define the control action which maintains the motion on the sliding manifold, an 'equivalent control' concept was used. It was simulated and implemented on a sensorless indirect vector drive for 150W two-phase induction motor. The simulation and experimental results demonstrated effectiveness of the estimation method.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.622-627
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• 2004

This paper investigated the speed sensorless indirect vector control of a two-phase induction motor to implement adjustable-speed drive for low-power applications. The sliding mode observer estimates rotor speed. The convergence of the nonlinear time-varying observer along with the asymptotic stability of the controller was analyzed. To define the control action which maintains the motion on the sliding manifold, an 'equivalent control' concept was used. It was simulated and implemented on a sensorless indirect vector drive for 150W two-phase induction motor. The simulation and experimental results demonstrated effectiveness of the estimation method.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.5
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• pp.375-380
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• 2003

In a conventional speed sensorless stator flux-oriented (SFO) induction motor drive, when the estimated speed is transformed into the sample-data model using the first-forward difference approximation, the sampled data model has a modeling error which, in turn, produces an error in the rotor speed estimation. The error is removed by the use of a low pass filter (LPF). As a result, the delay of the estimated speed occurs in transients by the use of the LPF. This paper proposes a method to estimate exactly the speed by using Luenberger observer to solve the problem of a conventional method.

• Journal of KIEE
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• v.11 no.1
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• pp.62-68
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• 2001

In this paper it is proposed an advanced modified sliding mode control of a rotor field oriented control of induction motor. The application of this unconventional control has very good results, such as disturbance rejection and nice dynamic properties. Stability can be guaranteed even in the worst situation. A conventional "sliding mode" controller is characterised by fast switching control signal, which causes the chattering of the drive system. To overcome this problem, a modified law is used, by introducing a hysteresis band and a continuous control, which modifies the conventional law. The control is accomplished with dual TMS320C44 floating-point digital signal processor. The validity of the proposed method was verified by experiment on the propulsion system simulator, used for the development of Korean High-Speed Railway Train(KHSRT).in(KHSRT).