• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.609-615
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• 2005

A 30kW electrical power conversion system is developed for a variable speed wind turbine. In the wind energy conversion system(WECS) a synchronous generator with field current excitation converts the mechanical energy into electrical energy. As the voltage and the frequency of the generator output vary according to the wind speed, a 6-bridge diode rectifier and a PWM boost chopper is utilized as an ac-dc converter maintaining the constant dc-link voltage with only single switch control. An input current control algorithm for maximum power generation during the variable speed operation is proposed without any usage of speed sensor. Grid connection type PWM inverter converts dc input power to ac output currents into the grid. The active power to the grid is controlled by q-axis current and the reactive power is controlled by d-axis current with appropriate decoupling. The phase angle of utility voltage is detected using software PLL(Phased Locked Loop) in d-q synchronous reference frame. Experimental results from the test of 30kW prototype wind turbine system show that the generator power can be controlled effectively during the variable speed operation without any speed sensor.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.3
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• pp.216-222
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• 2017

The rotor position of a PM synchronous motor is commonly estimated from the mathematical model for the sensorless control without rotor position sensors. For the magnet flux-based rotor position estimator in the stationary reference frame, the magnet flux estimator for estimating rotor position and speed includes the integrator. The integrator in the magnet flux estimator may accumulate the offset of the current sensors and the voltage drift. This continuous accumulation of the offset may cause the drift and overflow in the integrator, such that the estimated rotor position and speed may fail to track the real rotor position and speed. In this paper, the magnet flux estimator without integrator is proposed to avoid overflow in the integrator. The proposed rotor position and speed estimator based on magnet flux estimator are verified through simulation and experiment.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.21-24
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• 2000

In this paper, We introduce effective handoff method from W-COMA system of 3$^{rd}$ generation to 15-95 system of 2$^{nd}$ generation. In case of this handoff, Ms should know long code state using traffic channel, timing information and pilot offset of 26 synchronous system during the compressed mode. So We establish additional common channel in order to obtain handoff information. Common channel transmits same information from all base stations and provides MS with timing information of zero offset. long code state and timing of super frame for sync. channel. Therefore during the compressed mode. MS can obtain information for handoff using common channel..

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.160-163
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• 1991

Permanent Magnet Synchronous Motor(PMSM) has merits in both simple electrical controllability of dc motor and mechanical reliability of ac motor by applying vector control. The vector control method orients the armature current phasor to be perpendicular to the permenant magnet rotor flux in a two-axis coordinate frame, and provides control characteristics that are similar to those of separately excited dc motors. This paper presents a simple model following scheme for position control of PMSM fed by hysteresis current-controlled PWM inverter. The simulation results show the validity of the proposed control method.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.144-146
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• 2003

This paper presents a new speed sensorless control algorithm of a permanent magnet synchronous motor based on instantaneous reactive power. The proposed algorithm is constructed by instantaneous reactive power in the stationary reference frame and is not affected by mechanical motor parameters, because mechanical equation is not used. The effectiveness of the proposed algorithm is verified by the experimental results.

• Journal of Power Electronics
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• v.9 no.5
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• pp.748-756
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• 2009

This paper presents a compensation algorithm for position error due to an amplitude imbalance between resolver output signals. Resolvers are typically used to obtain absolute position information for motor drive systems in severe environments. Position error is caused by an amplitude imbalance of the resolver output signals. As a result, the d- and q-axis currents of synchronous reference frame have periodic ripples in the stator fundamental frequency in permanent magnet synchronous motor (PMSM) drive systems. Therefore, this paper proposes a compensation algorithm to reduce the position error generated by the amplitude imbalance. The proposed method does not require any additional hardware, and reduces computation time with a simple integral operation according to rotor position. In addition, the position error can be directly compensated for by the estimated position error. The effectiveness of the proposed compensation algorithm is verified through several simulations and experiments.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1167-1171
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• 1992

A predictive current control in the synchronous reference frame with the back EMF estimation using the previous voltages and currents is proposed. To reduce the torque ripple produced by harmonics in the air gap flux, the q-axis current is compensated using the estimated torque constant. The effectiveness of the proposed control is compared to the conventional control scheme through the simulation.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1243-1250
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• 2013

A model of a permanent magnet synchronous motor (PMSM) with an inter turn short fault is proposed using a deformed flux model. The deformed flux model includes not only the fault winding flux information but also the inductance variation of the healthy winding considering the configuration of the winding distribution. With the deformed flux model and the positive sequence current assumption, the proposed model is derived in the positive and negative sequence synchronous reference frame (SRF). The finite elements method (FEM) simulation is applied to validate the proposed PMSM model with inter turn short fault.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1813-1819
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• 2016

In this paper, LS-SynRM (Line Start-Synchronous Reluctance Motor) has been attracting attention in replace of induction motor which hardly provides high efficiency. Compared to induction motor, LS-SynRM has better efficiency per unit area. This study demonstrated the electromagnetic design methods of LS-SynRM while maintaining the frame of existing IE3 induction motor for blower. We documented the design procedures for generating high saliency which is the most essential and mechanical stress analysis is also treated. In conclusion, we proved the validity of our design by manufacturing and testing our LS-SynRM models.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.630-635
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• 1998

This paper establishes in a new unified manner new mathematical models with core(iron) loss factor for two kinds of AC motors, induction and synchronous motors which are supposed to generate torque precisely or/and efficiently under vector controls. Our new models consist of three basic equations consistent with the others such as differential equation describing electromagnetic dynamics, torque equation describing torque generating mechanism, energy transmission equation describing how injected energy is wasted, saved or transmitted where all vector signals are defined in general frame of arbitrary instant angular velocity. It is clearly shown in our models that equivalent core-loss resistance can express appropriately and separately both eddy-current and hysteresis losses rather than mere vague loss. Proposed model of induction motor is the most compact in sense of the number of employed interior states and parameters. This compact model can also represent eddy-current and hysteresis losses of rotor as well as stator. For synchronous motor, saliency is taken into consideration. As well known model for cylindrical motor can be obtained directly from salient one as its special case.