• Journal of Power Electronics
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• v.16 no.3
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• pp.894-904
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• 2016

This study examines the zero-voltage switching (ZVS) operation of an active-clamped forward converter (ACFC) with a current-doubler rectifier (CDR). The ZVS condition can be obtained with a much smaller leakage inductance compared to that of a conventional ACFC. Due to the significantly reduced leakage inductance, the design is optimized and the circulating loss is reduced. The operation of the ACFC with a CDR is analyzed, and a detailed ZVS analysis is conducted on the basis of a steady-state analysis. From the results, a design consideration for ZVS improvement is presented. Loss analyses of the converters shows that enhanced soft-switching contributes to an efficiency improvement under light-load condition. Experimental results from a 100-W (5-V/20-A) prototype verify that the ACFC with a CDR can attain ZVS across an extended load range of loads and achieve a higher efficiency than conventional ACFCs.

• Journal of Power Electronics
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• v.11 no.6
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• pp.787-792
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• 2011

In this paper, a new three phase soft switching inverter is presented. All of the semiconductor elements of this converter are soft switched. Employing only two auxiliary switches as DC-link switches and a simple control circuit are the advantages of the proposed inverter. The analytical equations and operating modes of the presented inverter are explained in details. The design considerations are presented and the experimental results verify the theoretical analysis.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.984-987
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• 2000

In switched reluctance motor(SRM) drive, it is necessary to synchronize the stator phase excitation with the rotor position. Therefore the rotor position information is an essential. Usually optical encoders or resolvers are used to provide the rotor position information. These sensors are expensive and are not suitable for high speed operation. In the paper, the low cost linear encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple digital logic circuit is also presented in this paper. It is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.325-327
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• 1998

Disk type single-phase switched reluctance motor which has an advantage of simple robust construction, simple control circuity, and low manufacturing cost has a specific property of axial flux machine and radial flux machine simultaneously. So, this DSPSRM has a complicated magnetic circuit and it is difficult to analyze characteristics of DSPSRM for design. In this paper, we used to analyze the effects of radial flux and axial flux simultaneously by 3D-finite element method. From the results of 3-D FEM, we obtained the approximated torque characteristics of DSPSRM. It's analysis results can be used in optimal design of DSPSRM considering the saturation.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.257-259
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• 1998

The Switched Reluctance Motor (SRM) has good properties to the adjustable speed control. But, high torque ripple and noise decrease this merit and make unstable state. Also, because of the saturation in the magnetic circuit, it is difficult to predict the inductance profile. If the inductance pronto is known, it's possible to make flat-top torque by applying some control strategy. This paper suggests method to develope flat-top torque using a Artificial Neural Network(ANN) method that can calculate a nonlinear inductance profile.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.735-740
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• 2001

With the development of micro-technology, the demand for micro actuator is increasing. But, it is difficult to achieve high resolution and long travel range simultaneously with the conventional actuators. So, the noncontact surface actuator was proposed. This actuator can realize high dynamic range and the planar motion without complex cross-axis linear slides. This paper describes a magnetically suspended linear actuator for developing a non-contact surface actuator. The operating principle and the structure of the proposed linear actuator are similar to switched reluctance motor, but the proposed linear actuator utilizes normal force and propulsion force simultaneously. With this characteristic, the system can be simpler than other non-contact surface actuator.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.62
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• pp.11-20
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• 2001

At the initial deployment of B-ISDN, the heterogeneity of services and the bandwidth requirement make dimensioning of B-ISDN much more complicated than the dimensioning of homogeneous circuit or packet switched networks. Therefore B-ISDN must be extended gradually according to future telecommunication technology or service demands. In this paper, we propose a mathematical formulation for dimensioning problem of B-ISDN extension, considering the characteristics of ATM(Asynchronous Transfer Mode) such as various quality of services, the statistical multiplexing effects of VPCs(Virtual Path Connections) and the modularity of transmission links allocated when new B-ISDN nodes are given. The algorithm based on the simultaneous linear approximation technique and Lagrangian relaxation method and some numerical results are also presented.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.865-868
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• 1993

This paper describes a simple random signal generator employing by CMOS analog technology in current mode. The system is a nonlinear dynamical system described by a difference equation, such as x(t＋1) = f(x(t)) , t = 0,1,2, ... , where f($.$) is a nonlinear function of x(f). The tent map is used as a nonlinear function to produce the random signals with the uniform distribution. The prototype is implemented by using transistor array devices fabricated in a mass product line. It can be easily realized on a chip. Uniform randomness of the signal is examined by the serial correlation test and the $\chi$2 test.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.6
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• pp.359-367
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• 2004

The switched reluctance motor(SRM) has considerable potential for industrial applications because of its high result lily as a result of the absence of rotor windings. In some applications with SRM, paralleling strategy is often used for cost saving, increasing of current capacity and system reliability. A SRM inverter has very low ,switching frequency. This results in reducing the burden for a high-speed of the gate-amp interface circuit. and the linearity of optocoupler is used to protect the instantaneous peak current for the stable operation. In this paper, series resistor is used to equal the current sharing of each switching device and a linear gate-amp is proposed to protect the instantaneous peak current which occurs in transient state. The proposed paralleling strategy is verified by experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.4
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• pp.188-194
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• 2003

The SRM (Switched Reluctance Motor) has a more inherent simple mechanical structure, greater ruggedness and higher efficiency than a conventional AC motor. It is for these reasons that SRM is widely applied in an extensive range of industrial applications. In this paper, SRM is designed and analyzed for EPS (Electrical Power Steering) application. Electrical power steering in a vehicle plays the role of reducing a driver's handling control power. For proper design, a FEM analysis is implemented according to the rotor structure. Using both a FEM and a magnetic circuit analysis, a designed motor is simulated and tested. The effectiveness of the suggested SRM drive for EPS application is verified by the prototype motor drive tests.