• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.35-38
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• 2006

The polarized direction of MT field was analyzed using the MT dataset measured in the Korean Peninsula. The atmospherics above 1 Hz has a large dispersion of polarized direction, whereas the Schumann resonance near 8 Hz exhibits the predominant direction ranging from $N20^{\circ}W$ to NS. The electromagnetic field variations below 0.1 Hz, induced by magnetic pulsations, show a strongly polarized direction of nearly NS. It results from the regular pulsations since the regular pulsation fields, driven by Alfv.n's wave in the magnetosphere, has a worldwide predominant direction of NS. The MT field strongly polarized along NS direction causes the poorly behaved XY impedance.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.256-262
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• 1998

The torque of SRM depends on phase current and the derivative of inductance. But the inductance of SRM is nonlinearly changed according to rotor position angle and phase current because of saturation in magnetic circuit, and it is difficult to control the desired torque. This paper proposes inductance modeling method using ANN(Artificial Neural Network) that is used to simulate the inductance which is nonlinearly varied with rotor position and current. The torque ripple is analyzed and input voltage and current condition to reduce torque ripple is simulated by inductance model.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.46-52
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• 1998

This paper describes a current-shaping method for the production of constant torque of SRM under the nonlinear magnetic saturation condition. A current detection technique in the inductance increasing region and an approximation technique for modeling of nonlinear inductance profile are adopted. In the proposed system, a single switching angle control and voltage control is used to shape the current waveform for the generation of flat torque at any given load condition. Finally the validity of the proposed method was verified using a constructed 3HP 6/4 SRM.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.263-272
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• 1998

This paper presents the new control strategy that can minimizes the torque ripple by considering the magnetic nonlinearity and phase torque averlapping intervals, and describes the whole SRM drive system using proposed control method implemented by DSP(Digital Signal Processor). To do this, inductance and torque are, at first, measured according to the variation of rotor position angle while current is kept constant at predetermined several values. From these measured values, the entire inductance and torque for any current and rotor position are inferred by using neural network. And the waveform of the reference phase torque is determined for the torque ripple to be minimized considering the torque overlap between phases. The controller is designed for the actual torque obtained by the inferred torque look-up table using measured current and rotor position angle to track the predetermined reference phase torque by delta modulation technique. To perform a real time processing and ensure the reliability of the controller, DSP is implemented.