• 대한전기학회논문지
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• 제40권7호
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• pp.643-655
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• 1991

The analysis method on air gap permeance distribution, air gap MMF distribution, air gap flux density distribution, cogging torque and BEMF about the skewed stator slots or the skewed rotor magnet segments for BLDCM, respectively, is studied as a function of the skew ratio. The proposed method describes the differences between the skewed stator slots and teh skewed rotor magnet segments for the air gap permeance distribution, air gap MMF distribution and air gap flux density distribution. The reliability of the method is also confirmed by the waveform of the cogging torque and BEMF through experiments. And the result shows that the effects on the cogging torque and BEMF due to the skewed stator slots or the skewed rotor magnet segments are the same. In case of the skewed stator slots, the effects of the variations of the winding resistance and inductance are also studied.

• Transactions on Control, Automation and Systems Engineering
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• 제4권4호
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• pp.253-263
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• 2002

This paper presents an adaptive feedback linearization control scheme for induction motors using stator fluxes. By using stator flukes as states, overparameterization is prevented and control inputs can be determined straightforwardly unlike in existing schemes. This approach leads to the decrease of the relative degree for the flux modulus and thus yields a simpler control algorithm than the prior results. In this paper. adaptation schemes are suggested to compensate for the variations of stator resistance. rotor resistance and load torque. In particular, the adaptation to the variation of stator resistance with a feedback linearization control is a new trial. In addition, to improve the convergence of rotor resistance estimation, the differences between stator currents and its estimates are used for the parameter adaptation. The simulations show that torque and flux are controlled independently and that the estimates of stator resistance, rotor resistance, and load torque converge to their true values. Actual experiments on a 3.7㎾ induction motor verify the effectiveness of the proposed method.

• Journal of Power Electronics
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• 제9권4호
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• pp.654-666
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• 2009

Direct torque control (DTC) of induction machines (IM) is a well-known strategy of these drives control which has a fast dynamic and a good tracking response. In this paper a nonlinear DTC of speed sensorless IM drives is presented which is based on input-output feedback linearization control theory. The IM model includes iron losses using a speed dependent shunt resistance which is determined through some effective experiments. A stator flux vector is estimated through a simple integrator based on stator voltage equations in the stationary frame. A novel method is introduced for DC offset compensation which is a major problem of AC machines, especially at low speeds. Rotor speed is also determined using a rotor flux sliding-mode (SM) observer which is capable of rotor flux space vector and rotor speed simultaneous estimation. In addition, stator and rotor resistances are estimated using a simple but effective recursive least squares (RLS) method combined with the so-called SM observer. The proposed control idea is experimentally implemented in real time using a FPGA board synchronized with a personal computer (PC). Simulation and experimental results are presented to show the capability and validity of the proposed control method.

• Journal of Power Electronics
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• 제5권1호
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• pp.11-19
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• 2005

This paper describes the two control techniques to perform the sensorless vector control of a PMSM by injecting the high frequency voltage to the stator terminal. The first technique is the estimation algorithm of the initial rotor position. A PMSM possesses the saliency which produces the ellipse of the stator current when the high frequency voltage is injected into the motor terminal. The major axis angle of the current ellipse gives the rotor position information at a standstill. The second control technique is a sensorless control algorithm that injects the high frequency voltage to the stator terminal in order to estimate the rotor position and speed. The rotor position and speed for sensorless vector control is calculated by appropriate signal processing to extract the position information from the stator current at low speeds or standstill. The proposed sensorless algorithm using the double-band hysteresis controller exhibits excellent reference tracking and increased robustness. Experimental results are presented to verify the feasibility of the proposed control schemes. Speed, position estimation and vector control were carried out on the floating point processor TMS320VC33.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.800-801
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• 2011

This paper proposes a grid-connected to rotor type doubly fed induction generator (DFIG) in which the rotor winding is connected to the grid instead of the stator winding. The stator size and weight of the proposed grid-connected to rotor type DFIG can be reduced because the proposed type can use rotor core more efficiently compared to the stator type DFIG. In order to verify the size and weight reduction of the proposed type, the loading distribution method (LDM) is utilized. As a design result, the stator outer diameter and weight of the proposed type were decreased. The equivalent circuit analysis and finite element method also performed to verify the design results and to analyze characteristics of the novel DFIG.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.111-114
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• 2004

CFD code that simulates stator-rotor interactions is developed applying parallel computing method. Modified Multi-Block Grid System which enhances perpendicularity in grid and is appropriate in parallel processing is introduced and Patched Algorithm is applied in sliding interface which is caused by movement of rotor. The experimental model in the turbo-machine is composed of 11 stators and 14 rotors. Analyses on two test cases which are one stator - one rotor model and three stators - four rotors model are performed. The results of the two cases have been compared with the experimental test data.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.192-195
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• 2002

The thesis proposes the sensorless vector control method that estimates the rotor speed and rotor time constant at the same time using stator current. In the proposed method, stator current error in the stationary reference frame is proportional to estimated speed error, and stator current error in the synchronous reference frame is proportional to estimated rotor time constant error. The proposed method can simultaneously produce a fast speed estimation and rotor time constant estimation. Therefore, this new method offers an improvement in the performance of a sensorless vector controller. And, the superiority of the proposed method is verified by simulation.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1315-1323
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• 2014

Although the power density in Double Stator Switched Reluctance Motor (DSSRM) has been improved, the torque ripple is still very high. So, it is important to reduce the torque ripple for specific applications such as Electric Vehicles (EVs). In This paper, an effective rotor shaping optimization technique for torque ripple reduction of DSSRM is presented. This method leads to the lower torque pulsation without significant reduction in the average torque. The method is based on shape optimization of the rotor using Finite Element Method and Taguchi's optimization method for rotor reshaping for redistribution of the flux so that the phase inductance profile has smoother variation as the rotor poles move into alignment with excited stator poles. To check on new design robustness, mechanical analysis was used to evaluate structural conformity against local electromagnetic forces which cause vibration and deformation. The results show that this shape optimization technique has profound effect on the torque ripple reduction.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.30-36
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• 2002

This paper presents a developed deep slot squirrel cage induction motor fur the fan. Nearly all of the induction motors consist of two parts, rotor and stator, and the position of rotor is generally inside of stator. However, the rotor of the developed induction motor is located outside of stator. It is believed that the outside rotor type induction motor is suitable for the fan due to its large inertia, that is, it is considered that the change of air flow rate resulting from input power or load fluctuation is reduced. It is considered that the results of this paper can be used for the development of the outside rotor type induction motor.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권6호
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• pp.324-329
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• 2004

Six stator slot couplers(SSC) and a flux probe sensor installed on the stator winding slots of large turbine generator. Assessment of insulation condition has been based upon the measurements of partial discharge(PD) of stator windings and shorted-turn of rotor windings in operating large turbine generator. The maximum PD magnitude(Qm), normalized quantify number(NQN), PD pattern and shorted-turn were measured using on-line insulation condition monitoring system. The NQN and Qm of slot PD side in the phase A are indicated the highest value in six SSC sensors. Monitoring system results showed that discharge at conductor surface and internal discharge were detected at the surface of stator winding and in voids of the groundwall insulation. Insulation of stator and rotor windings in large turbine generator was judged to be in good condition.