• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.1
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• pp.30-36
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• 2004

An iterative sliding mode observer is proposed to sensorless control of a PMSM(Permanent Magnet Synchronous Motor). The proposed sliding mode observer has the character which is robust to the disturbance and parameters variation. A low pass filter with the variable cut-off frequency is also proposed to compensate the delay of the rotor angle according to the rotor speed, it is led to save memory and minimize operation time. Experimental results show that the proposed sliding mode observer leads to the proper performance.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.88-95
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• 2001

Stator core loss has significant adverse effects when an induction motor is controlled by the conventional vector control method. Therefore, taking core toss into account should make it possible to control the torque very precisely. This paper proposes a speed sensorless vector control method for an induction motor at optimum efficiency and high response taking core loss account. The proposed vector control system consists of a speed adaptive rotor flux observer which takes core loss into account and employs a direct vector control which compensates for the influence of core loss. Also, in this paper, a vector controlled induction motor with a deadbeat rotor flux controller is developed. The method ensures optimum efficiency in the steady state without degradation of the dynamic response. The validity of the proposed technique is confirmed by simulation results for induction motor drive system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.50 no.3
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• pp.117-124
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• 2001

The aim of this paper is to develop a controller of multi-phase bipolar brushless DC (MPB BLDC) motors for an electric bicycle. A MPB BLDC motor has a Permanent magnet rotor in which the magnetic arrangement is radial to the shaft and integral to the rotor laminations. This technique concentrates flux, giving a higher flux density than a surface-mounted PM motor and increases reluctance torque. The stator of MPB BLBC motor has parallel winding, allowing multi-phase separate independent controllability. It gets much more high power than wye-connection at same low voltage. The conventional techniques of exited with modulation(EWM), bidirection control, and partial square wale control are Proposed with one H-bridge and two photo sensors per phase. The Proposed controller is satisfied for the limited speed control and designed for system stability Experimental results show the performance of the proposed controller of MPB BLDC motors for an electric bicycle.

• Journal of Power Electronics
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• v.19 no.3
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• pp.794-802
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• 2019

Magnetic geared motors are driven using the same operating principle as conventional synchronous motors in which a magnetic gear is embedded. The magnetic geared motor is structurally similar to a magnetic gear. However, by applying currents to the stator coil, the high-speed rotor is rotated by a magnetic field and the low-speed rotor is rotated according to the gear ratio. In this paper, the operational principle of a magnetic geared motor and the magnetic flux density in its inner and outer air gaps are described. Then the magnetic flux density in the two air gaps is used to express a method for calculating the electrical and mechanical output. Results obtained with the analytical calculation method are compared with those of the finite element analysis. Finally, a prototype is used to verify the results of the analytical calculation and FEA.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2809-2818
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• 2022

In this investigation work, liquid-liquid extraction (L.L.E) through three distinctive frameworks have been examined for assurance of slip velocity (S.V), and characteristic velocity (C.V) in a non-center rotating column (N.C.R.C) with a wide extend of factors. Three double frameworks with distinctive interfacial tension comprising of toluene-water (high interfacial tension), n-butyl acetate-water (medium interfacial tension), and n-butanol-water (low interfacial tension) were investigated for tests. Two common relationships for the expectation of S.V and C.V, including phase stream rates, rotor speed, column geometry additionally physical properties, are displayed. The recommended relationships were compared with test information gotten from the writing and the display examination. Findings of this study, the present proposed correlations are more accurate than those previously reported.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.319-326
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• 2002

In switched reluctance motor(SRM) drive, it is important to synchronize the stator phase excitation with the rotor position; therefore, the information about rotor position is essential. Generally, optical encoders or resolvers are used to provide the information. However, these sensors are expensive and are not suitable for high-speed operation. The accuracy of the switching angles is dependent upon the resolution of the encoder and the sampling period of the microprocessor. In the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost linear encoder suitable far the practical and stable SRM drive is proposed and also the control algorithm to generate the switching signals using a simple digital logic is presented. The validity of the proposed linear encoder with a proper logic controller is verified through the experiments.

• The KSFM Journal of Fluid Machinery
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• v.6 no.3 s.20
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• pp.44-50
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• 2003

An experiment is conducted for measuring the performance of an air tool, which is operated at 100,000 RPM in an unloaded state with very low torque. A 551 kPa in gauge pressure is supply to the inlet of an air tool. An experimental apparatus is developed as a friction type dynamometer. Inlet total pressure, air flow rate, rotational speed and operating force are measured simultaneously. Torque, output power and specific output power are obtained with different rotational speeds. Those are compared with the experimental results which were obtained by a commercial dynamometer. However, no commercial dynamometers are available for measuring the torque above 30,000 RPM. In order to reduce the rotational speed, a reduction gear is applied between the air tool and the commercial dynamometer. Torque and power obtained by the commercial dynamometer show $55\%$ lower than those obtained by the developed friction type dynamometer, because the mass is added to the rotor of air tool for the braking system of the commercial dynamometer and power loss is generated by the reduction gear. From the compared results, the friction type dynamometer should be applied for measuring the performance of the air tool operating at low torque and high RPM.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.261-267
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• 2009

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. Therefore, it is important to recognize the effect of unbalance mass. This paper presents analysis of dynamic behavior of a high speed spindle with a built-in motor. The spindle is supported by the angular contact ball bearings and the rotor is fixed at the middle of spindle. The spindle used in CNC automatic lathe has been investigated using combined methodologies of finite elements and transfer matrices. The Houbolt method is used for the integration of the system equations and the dynamic behavior of spindle is obtained considering unbalance mass of rotor. Results show that increasing rotational speed of spindle magnifies the whirl responses of spindle seriously. Also the whirl responses of spindle are affected by the other factors such as unbalance mass and bearing stiffness.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.266-270
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• 2007

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint face, and energy required for welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy, amount of upset, working time, and residual stresses in the joint. Inertia welding was conducted to make the large rotor shaft for low speed marine diesel engine, alloy steel for shaft of 140mm. Due to material characteristics, such as, thermal conductivity and high temperature flow stress, on the two sides of the weld interface, modeling is crucial in determining the optimal weld parameters. FE simulation is performed by the commercial code DEFORM-2D. A good agreement between the predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.752-760
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• 2018

In this paper, interior permanent magnet synchronous motor (IPMSM) design for sensorless drive, considering magnetic neutral point shift according to magnetic saturation, has been proposed. Sensorless control was divided into a method based on inductance and a method based on back induced voltage. Because induced voltage is very small at zero or low speed, error in rotor initial position estimation may occur. Using the ratio of saliency addresses this problem. When using high-frequency injections at low speed, the rotor's initial position is estimated at the smallest portion of the inductance. IPMSM has the minimum inductance at the d-axis. However, if magnetic saturation leads to magnetic neutral point variation, following the load current change, there is a change in the minimum point of inductance. In this case, it can lead to failure of initial rotor position estimation. As a result, it is essential that the blocking design has an inductance minimum point shift. As such, in this study, an IPMSM design method, by blocking magnetic neutral point change, has been proposed. After determining the inductance profile based on the finite element analysis (FEA), the results of proposed method were verified.