• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.916-924
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• 2015

Electromagnetic Interference (EMI) is a system to system or environment to system phenomenon. The literature survey proved that the Randomized Pulse Width Modulation (RPWM) technique is a promising technique to reduce EMI. A new Constant Trailing Edge, Randomized Pulse Width Modulation (CTERPWM) technique is proposed in this paper. The effect of the proposed RPWM technique for mitigation of conducted-EMI on Cuk converter operating in Continuous Conduction Mode (CCM) is simulated and tested. In this paper, the analytical expressions for the Power Spectral Density (PSD) are derived for the proposed RPWM technique and are validated by experimental measurements. The effectiveness of the proposed RPWM technique on the mitigation of conducted-EMI is verified comparing simulation and experimental results and it is identified that both the results are almost similar with allowable experimental deviations. The comparative investigation proves that the proposed RPWM technique can mitigate and spread the dominant peaks of conducted-EMI over the complete spectrum for the Cuk converter. Based on the investigation the CTERPWM technique is recommended for adoption.

• Journal of Power Electronics
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• v.15 no.2
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• pp.327-337
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• 2015

This study discusses the design of a parallel-operated DC-DC single-ended primary-inductor converter (SEPIC) for low-voltage application and current sharing with a constant output voltage. A coupled inductor is used for parallel-connected SEPIC topology. Generally, two separate inductors require different ripple currents, but a coupled inductor has the advantage of using the same ripple current. Furthermore, tightly coupled inductors require only half of the ripple current that separate inductors use. In this proposed work, tightly coupled inductors are used. These produce an output that is more efficient than that from separate inductors. Two SEPICs are also connected in parallel using the coupled inductors with a single common controller. An analog control circuit is designed to generate pulse width modulation (PWM) signals and to fulfill the closed-loop control function. A stable output current-sharing strategy is proposed in this system. An experimental setup is developed for a 18.5 V, 60 W parallel SEPIC (PSEPIC) converter, and the results are verified. Results indicate that the PSEPIC provides good response for the variation of input voltage and sudden change in load.

• Journal of IKEEE
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• v.23 no.4
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• pp.1140-1149
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• 2019

In general, there are various pulse width modulation(PWM) methods simply using the offset voltage injection in voltage source converter(VSC). In accordance with the AC side voltage synthesis method with the offset voltage, DC side voltage utilization factor in VSC is changed. Also, this can apply equally to the MMC system. In other words, if the DC side capacity of the high voltage DC(HVDC) transmission system is determined, the maximum reactive power which can be supplied to the AC side can be changed according to the applied output voltage synthesis method with the offset voltage. In this paper, the leg energy pulsation in MMC system according to the AC side output voltage synthesis method with offset voltage which several representative PWM are applied to are mathematically analyzed and compared with each other. Finally, the above results are verified by simulation emulating the 400MVA full-scale MMC system to determine the consistency of the mathematical analysis.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.442-443
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• 2011

In this paper, a voltage control method based on DQ transformation and Space Vector Pulse Width Modulation (SVPWM) for a single phase three-level converter is proposed. This control method is designed to use DC values instead of using instantaneous values of current which are usually used in single-phase application, so that it results in a fast and robust voltage control response. Simulation results demonstrate the validity of the control strategies.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.65-67
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• 2008

A new pulse width modulation method based on predictive current control strategy is proposed to modulate matrix converters. The predictive current controller utilizes a discrete-time model to predict the future values of output currents and generates proper duty-ratios ta minimize the output current errors. The proposed method uses continuous carrier and establishes a predictive current controller to predetermine duty ratio signal for directly generating gating signals an thus is named "predictive current control PWM(PCCPWM)". The modulation algorithm nd the required equations are derived by using average concept over one switching period. Thus it can be easily extended to other matrix converter topologies, especially with neutral connections, such as sing le-phase ad two-phase matrix converters. The feasibility and validity of the proposed strategy are verified by computer simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.81-94
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• 2010

This paper presents a high efficiency resonant asymmetrical half-bridge flyback converter. The primary half-bridge circuit of the converter operates by a soft-switching type using the asymmetrical pulse-width modulation (PWM) method with the resonant capacitance and transformer leakage inductance. The secondary flyback circuit of the proposed converter utilizes a synchronous rectifier, which operates by a new voltage-driven method with a simple drive circuit. Thus the proposed converter improves the total efficiency. This paper explains the operational principle of the proposed converter by each mode and shows the converter design consideration and a design example for the prototype converter, respectively. After that, the proposed simple driving technique of the synchronous rectifier by a voltage-driven method is explained, briefly. The designed prototype converter has wide input voltage (AC $V_{in,rms}$=75~265[V]), 5[V] DC output voltage, and 100[W] output power. To verify the excellent performance of the proposed converter, the designed prototype is implemented and experimented. The good performance of the proposed converter is shown through the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.120-125
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• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1142-1146
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• 1992

This paper deals with the operation analysis of the half-bridge parallel-resonant converter with P.W.M. control. The converter operates at fixed frequency, in the continuous and discontinuous current mode. A simplified theorectical steady-state analysis is developed and the converter characteristics are presented.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.709-712
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• 1998

A new ZVS-CV PWM converter with power factor correction (PFC) function is presented in this paper. The new topology is a integration of a boost converter and a ZVS-CV topology in a single power conversion stage. The new converter can be regulated in pulse-width modulation (PWM) by universal integrated control circuits. Some design considerations are given in detail. A laboratory prototype has been implemented to show the feasibility of the approach and the analysis.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.283-284
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• 2013

This paper proposes a fault-tolerant strategy for indirect matrix converter (IMC) based on the concept of four-leg matrix converter in case of an open-circuit fault in the inverter stage. The proposed strategy can maintain the same output performance as the healthy condition during the faulty condition. Some simulated results are provided to verify the effectiveness of the proposed strategy.