• Journal of Power Electronics
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• v.12 no.1
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• pp.120-127
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• 2012

Fault diagnosis technique of electrical drives is becoming more and more important, since voltage fed converter system has become industrial standard in many applications. Many studies have been conducted an inverter fault diagnosis for induction motors. However, there are few researches about fault diagnosis of 3-phase ac/dc PWM (Pulse Width Modulation) converter compared to the dc/ ac inverter. The ac/dc converter is the opposite of dc/ac inverter at current flow. Also, inverter and converter have different current patterns under the same condition of IGBT (Insulated gate bipolar transistor) open switch fault. Therefore, it is difficult to apply intact diagnosis methods of inverter to the converter. This paper proposes modified fault detection methods for IGBT open switch fault in 3-phase ac/dc PWM converter by modifying established fault diagnostic methods for dc/ac inverters.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.520-528
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• 2006

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion). and we used the phase-shift switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1047-1050
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• 1998

This paper describes an advanced prototype of voltage-fed zero voltage soft-switching PWM resonant inverter with an active voltage clamped capacitor, which is put into practice for high-frequency high-power induction-heated appliances. This application-specific quasi-resonant inverter using the latest generation IGBTs for soft-switching can regulate its output power under a principle of a fixed frequency ZVS-PWM strategy. Its operating principle and unique features are presented as compared with a conventional quasi-resonant ZVS inverter for induction-heated cooker, together with its power regulation characteristics on the basis of its simulation and experimental results. The steady-state performances of this inverter developed for multi-burner type induction-heated food cooking appliance are evaluated and discussed from a practical point of view.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.623-635
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• 1987

A new suboptimal PWM is proposed, intended particularly for the reduction of acoustic noise and harmonics of the output current in the inverter-fed induction motor drive system. This strategy is based of the Regular PWM and applied optimal techniqe. And it could solve a problem that computation time is very much when switching strategy is determined at the Optimal PWM. In case that the number of switching increases infinitely, this strategy could determine the switching pattern, and can realize Online, Real time of microprocessor. Also, this strategy is applied to 1(Hp), three phase induction motor, and compared with the other PWMs. From the results, the validity of this strategy could be verified.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1055-1057
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• 2001

The switching circuit of PWM inverter is very complicated. By using one-chip $\mu$-com the complication of switching circuit is possible to be diminished. But because in one-chip $\mu$-com the limitation of processed memory size exists, the switching handling method has to be simple. In this paper, to effectively utilize the switching handling, we presented the estimation method of PWM pulses which is different form the conventional PWM switching method by the comparison.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.34-37
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• 2001

This research suggested the new algorithm controlled by micro processor which is already stored by various PWM form of output voltage by using fundamental data of the carrier and signal. The determined PWM pattern is not concerned with the signal wave form and the new algorithm can obtain the desired pulse width by synchronous of carrier. The PWM wave can be controlled with real time by using extra hardware and digital software and to speed up program processing, the control signals to switch the power semi-conductor of three phase PWM inverter, simultaneously use the output signal by microprocessor and extra hardware, and control signal by software. In the end, this method was proved by applying to Three phase voltage source inverter.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.1
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• pp.42-48
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• 1988

MM(multimode) PWM(pulse width modulation) Suitable for high performance and harmonic effects minimization of VSI (voltabge source invertetr)-IM (induction motor)drive system is proposed. The approximated optimal, suboptimal and optimal PWM are implemented in the low frequency range, while square wave operation is realized in the hibh frequency range. The pulse width Modulator is capable of generating control signals to a transistorized inverter operating at about 1KHz. All functions except digital comparison have been implemented in softyware making the scheme economical, flexible and reliable. Pulse width modulator is built and tested experimentally. In order to confirm the effectiveness and the reliability of the theoretical proposition, this scheme is applied to 1Hp, Three phase IM. As results, it is concluded that the scheme of MM PWM is superior to other conventional switching scheme through the discussions or analysis carried out on the items such as line-to-line voltage, current and spectrum of current harmonic components observed at the output terminal of inverter, noise level of motor.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.253-254
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• 2006

this paper suggest a new space vector PWM modulation method with short processing time which does not need idenfication of nearest three vectors(NTV) and duty calculation for each vector. The suggested PWM method makes mean value of phase voltage to be same as reference during every modulation period by use of a triangle in small hexagon on multi-level vector space. This paper described the suggested modulation method can be successfully applied to the space vector modulation use of multi-level inverter by computer simulations and experiments.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.307-312
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• 1994

In this investigation the PFM(Pulse Frequency Modulation} will be used for optimizing PWM inverter pulse pattern. In traditional the pulse frequency of PWM is kept const. But modulated PWM's frequency in this study, the sinusoidal inverter's performance should be improved. The PWM pulsepatterns are definitely controlled so that the time-integral function of the voltage vectors in the space vector notation may show a circular locus. Further, performance index will be minimized because of minimizing distortion of output current. Finally, we will implement itusingsingle-chip microprocessor.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.328-335
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• 1999

Three phase full bridge rectifier has been used to obtain dc voltage from three phase ac voltage source. The rectifier system has drawbacks that power factor is low and power flow is unidirectional. Therefore, when dc voltage increases due to regeneration of power the dynamic resister for dissipation of regeneration power must be installed. But three phase PWM converter can be controlled to operate with unity power factor and bidirectional power flow. Therefore when the PWM converter is used as do supply system, the dissipating resistor is not necessary. On this thesis, in order to design a controller having good performance, the hee phase PWM converter is completely modeled by using circuit DQ-transformation and thus a general and simple instructive equivalent circuit is obtained; the inductor set becomes a second order gyrator-coupled system and three phase inverter becomes a transformer as well. Under given phase angle(${\alpha}$) and modulation index(MI) of the three phase inverter, the dc and ac characteristics are obtained by analysis of the transformed equivalent circuit The validity of the equivalent circuit is confirmed through PSPICE simulation. And based on the dc and ac characteristics a controller with unity power factor is proposed.