• Journal of Power Electronics
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• v.9 no.3
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• pp.377-385
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• 2009

In this paper, a diagnosis method for switch open-circuit faults in three-phase PWM inverters is proposed, which employs support vector machine (SVM) as classifying method. At first, a discrete wavelet transform (DWT) is used to detect a discontinuity of currents due to the fault, and then the features for fault diagnosis are extracted. Next, these features are employed as inputs for the SVM training. After training, the SVM produces an optimized boundary which is used identifying the fault. Finally, the fault classification is performed online with instantaneous features. The experimental results have verified the validity of the proposed estimation algorithm.

• 전기의세계
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• v.26 no.3
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• pp.76-83
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• 1977

The choice of control method and circuit must be decided after a broad inspection with the characteristics of load and control elements as well as that of electric and mechanical nature. In the present study, Pulse width modulated(PWM) SCR chopper was chosen and for the electric commutation, Jones' forced method was taken bacause of its having enough reverse bias energy. Objectives of experimentation by this system are; 1) the condition of SCR as a gate trigger pulse. 2) the observation of phenomena at the time of forced commutation 3) the experimentation on characteristics of speed control by PWM chopper. Above experimentation shows good characteristics, however, in the limit of narrow gap between the ON and OFF pulses, a complete control was not possible. So, that must be the point to be studied further alone with the harmonics influence.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.608-615
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• 2003

This paper describes an implementation of a DSP (Digital Signal Processor) controlled random carrier frequency modulation for the PWM inverter for acoustic noise reduction of induction motors. Real-time generation of the random variable and RPWM(Random PWM) along with the speed control was achieved by DSP TMS320C31. The experimental results show that the voltage and current harmonics are spread to a wide band area and the power spectrum of the acoustic switching noise was spread to create a more appealing, less annoying sound. Also, the speed response of the implemented method and the conventional method is nearly similar to each other from the viewpoint of the v/f constant control.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1829-1838
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• 1989

This paper is proposed one method of the exact optimal switching pattern of Selected Harmonic Elimination(SHE) Pulse Width Modulation(PWM). It defined Harmonic Elimination Band (HEB) at Constant Voltage(CV) and sought all solutions which are included HEB. Then, it calculated the Generalized Klirr Factor(GKF) beling to this solution and decided the optimal switching pattern which is minimized GKF. This optimal switching solution is used as initial condition of Newto Raphson(NR) method of decided easily switching pattern at Variable Voltage(VV). We desined the inverter by Power Transister(PTR) and implemented variable speed drive of Induction Motor(IM) in order to verify the validity of this theoretical proposition, then shown this results by comparison and analysis.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.33-37
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• 1998

For the high power variable speed applications, the DCTLI(diode clamped three-level inverter) have been widely used. This paper describes the analysis of the neutral point current of the DCTLI and the improved space vector-based PWM strategy considering the switching frequency of power devices, that minimizes the fluctuation of the neutral point current in spite of high modulation index region and low power factor. It contributes to decrease the capacitance of dc-link capacitor bank and to increase the neutral point voltage controllable region. Especially, even if second (or even) order harmonic is induced in load current (at this situation, is was investigated that the general control method can not suppress the neutral point voltage variation), this PWM can provide effective control method to suppress the neutral point voltage variation. Various simulation results by means of Matlab/Simulation are presented to verify the proposed PWM.

• Journal of Power Electronics
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• v.10 no.1
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• pp.14-20
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• 2010

In this paper, a tightly regulated triple output asymmetrical half bridge flyback (ASHF) converter is proposed. In order to regulate all output voltages, pulse frequency modulation (PFM), pulse width modulation (PWM) and phase delay (PD) are used simultaneously. In comparison with the conventional PWM-PD method, the interactions among the control variables are minimized and the operating range is increased. By the utilization of a multi winding transformer, the auxiliary transformer and the blocking capacitor are eliminated and the size and cost of the proposed converter is reduced. The operation principle of the converter is explained and the modes of operation are investigated. Based on the results, the steady state characteristics of the converter are explored. A 24V/10A, 12V/5A, 5V/10A hardware prototype is built and tested to verify the analysis results and the voltage regulation of the triple outputs of the proposed converter.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.281-283
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• 1995

Deadbeat controlled PWM Inverter is realized. This PWM inverter performs the instantaneous control method which is based on the real-time digital feedback control and the microprocessor-based deadbeat control. For the deadbeat current controller, the system's order becomes a high order and increases computation delay time. Therefore, The delay tine produces current ripple. To minimize the current ripple, a new method based on deadbeat control theory for current regulation is proposed. It is constructed by a reduced-order state observer which predicts the output current in next sampling instant.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.333-336
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• 2003

Designed transformer-less inverter for photovoltaic and small unit windturbine power system. This system consisted of boost chopper circuit of multiple-switching method and foil bridge PWM inverter. Transformer-less system was adapted to reduce cost and size. But in this system, earth-leakage current have to be considered. So, to solve this problem, we used PWM inverter switching method to reduce the earth-leakage current which flows in accordance with the variation of DC input common mode voltage.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.316-319
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• 1998

RPWM(Random Pulse Width Modulation) is a switching technique to spread the voltage and current harmonics on the wide frequency area. Using randomly changed switching frequency of the inverter, the power spectrum of the electromagnetic acoustic noise cab be spread to the wide-band area. The wide-band noise is much more comfortable and less annoying than the narrow-band one. So RPWM have been attracting an interest as an excellent method for the reduction of acoustic noise on the inverter drive system. In this paper a new RPPWM (Random Position PWM) is proposed and implemented. Each of three pulses is located randomly in each switching interval. Along with the randomization of PWM pulses, the space vector modulation is executed in the C167 microcontroller also. The experimental results show that the voltage and current harmonics were spread to wide band area and that the audible switching noise was reduced by proposed RPPWM method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.547-552
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• 2005

This paper describes a pseudo-random carrier PW technique for the power converters. The proposed method generates a new pseudo-random carrier by randomly composing a carrier with fixed frequency and a carrier with opposition phase. To confirm the validity of the proposed method, a single-phase multi-level inverter was implemented and tested. The experimental results show that the output voltage and current harmonics spectra of an inverter have broadening effect of harmonics, as only simple composition of fixed frequency carries.