• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.358-365
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• 2005

In induction machine drive without a speed sensor, the estimation of the motor flux and speed often becomes deteriorated at low speeds with low back EMF. Our analysis shows that, in addition to the state resistance variation, the estimated value of field orientation angle is often corrupted by accumulative errors from the integration of voltage variables at motor terminals that have low signal/noise ratio at low frequencies. A repetitive loop path of integration in the feedback can amplify this type of error, thus speeding up the degradation process. The control system runs into information starvation due to the loss of correct field orientation. The machine's spiral vectors are controlled only in a reduced dimension in this situation. A novel control scheme is developed to improve the control performance of motor's current, torque and speed at low frequencies. The scheme gains a full-dimensional vector control and is less sensitive to the combined effect of the error sources at the low frequencies. Experimental tests demonstrate promising performances are achievable even below 0.5 Hz.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권10호
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• pp.522-527
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• 2003

This paper proposes a new speed and flux estimation method which has the robustness against the variation of the electrical parameters of the motor and the superiority in the dynamic characteristics. In the proposed method, the stator currents and the rotor fluxes are observed on the stationary reference frame using the sliding mode concept. And the rotor speed is estimated using the current estimation errors and the observed rotor fluxes based on the Lyapunov stability theory. Also a design method of the observer gain is proposed to minimize the effect of the speed estimation error on the rotor flux observation. The experimental results are shown to verify that the proposed method shows the excellent performances under the variations of motor resistance and inductance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.317-319
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• 2001

A Switched Reluctance Generator attracts much attention in the generator because of high efficiency, simplicity, and ruggedness. However, they require rotor position information to operate. In many systems, the rotor position sensor is expensive, limited and undesirable. This paper describes a new approach to estimating the rotor position of a SRG from the measured terminal voltage and current for rotor position sensorless control. The proposed method Is based on the instantaneous inductance of the SRG. The proposed technique is very simple and it is able to apply to high speed operation under the stable condition because of its simplicity. The initial rotor position estimation algorithm is efficient and reliable. The proposed method is verified by computer simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2136-2138
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• 1998

In this study, the speed sensorless vector control system with the magnetizing inductance compensation structure is presented. The estimations of the rotor speed and the magnetizing inductance using the terminal voltages and currents are performed with the reduced order Gopinath flux observer. The rotor speed is estimated by the torque producing current which is derived from the estimated value of the rotor flux and the measured stator currents. In order to compensate the variation of the magnetizing inductance under the saturated conditions, we also established the compensation scheme which is made with the instantaneous reactive power. The validity of the proposed method is verified by simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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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.

• 전자공학회논문지B
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• 제30B권11호
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• pp.37-46
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• 1993

Recently, the elimination of speed sensors has been one of the important requirement in vector control systems, because the speed sensor spoil the ruggedness and simplicity of induction motor. This paper proposes sensorless vector control for high performance of induction motor. The proposed vector control scheme is based on a rotor flux and speed which are calculated from the stator voltage and currents with improved flux estimator. The characteristics of vector control employing stator voltage and current generally deteriorate as the speed gets lower acause the calculated rotor flux depends on the stator resistance and it is difficult to calculate rotor flux at low speed of standstill. This new control system is robust with respect to variations of the stator resistance and it makes possible to calculated rotor flux at low speed of standstill. These feature are verified by the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.64-66
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• 1999

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia and high efficiency. However, position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle. The proposed system consists of position decision, phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.684-686
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• 2000

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia. and high efficiency. However position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle for speed control. The proposed system consists of position decision. phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through the experiment.

• 산업기술연구
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• 제30권A호
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• pp.31-35
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• 2010

In this paper, a speed estimation method at coasting operation in an induction motor speed sensorless control for railway vehicle traction systems is presented. At coasting operation, there is no information obtaining rotor speed since all switches of an inverter are turned off. The inverter frequency should be synchronized with the rotor frequency for repowering at coasting condition. The proposed method injects DC current to the induction motor during a short time, then the flux angle and rotor speed needed for control can be estimated rapidly.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.272-275
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• 2001

In this paper, author consider the nonlinear control by using feedback linearization for independent control and estimation algorithm such as speed, rotor flux and rotor resistance to achieve sensorless control of induction motor. The dynamic characteristics of the proposed nonlinear control algorithm is verified by simulation.