• Journal of Power Electronics
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• v.17 no.1
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• pp.31-40
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• 2017

A novel voltage-fed single-stage power factor correction (PFC) full-bridge converter based on asymmetric phase-shifted control for battery chargers is proposed in this paper. The attractive feature of the proposed converter is that it can operate in a wide output voltage range without an output low-frequency ripple, which is indispensable in battery charger applications. Meanwhile, the converter can maintain a high power factor and a controllable dc bus voltage over a wide output voltage range. In this paper, the realization of PFC and the operation principle of asymmetric phase-shifted control are given. A small-signal analysis of the proposed single-stage power factor correction (PFC) full-bridge converter is performed. Experimental results obtained from a 1kW experimental prototype are given to validate the feasibility of the proposed converter. The PF is higher than 0.97 over the entire output voltage range with the proposed control strategy.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.155-157
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• 2005

This paper shows how to design a MPPT control of PV system using neural network PI self tuning. The conventional self-tuning methods have the voltage control problem of nonlinear PV system which can't adapt against any kinds of noise or operation circumstances. In this paper, supposed to solve these problem to PI parameters controller algorithm using ANN. In the proposed algorithm, the parameters of the controller were adjusted to reduce by on-line system the error of the output voltage of DC-DC chopper. In this process, EBPA NN was constituted to an output error value of a DC-DC chopper and conspired an input and output. The performance of the self-tuning controller is compared with that of the PI controller tuned by conventional method. The effectiveness of the proposed control method is verified thought the Matlab Simulink.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1270-1277
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• 2019

A problem with virtual synchronous generator (VSG) systems is that they are difficult to operate stably with photovoltaic (PV) power as the DC side. With this problem in mind, a PV-VSG control strategy considering the dynamic characteristics of the DC side is proposed after an in-depth analysis of the dynamic characteristics of photovoltaic power with a parallel energy-storage capacitor. The proposed PV-VSG automatically introduces DC side voltage control for the VSG when the PV enters into an unstable working interval, which avoids the phenomenon where an inverter fails to work due to a DC voltage sag. The stability of the original VSG and the proposed PV-VSG were compared by a root locus analysis. It is found that the stability of the PV-VSG is more sensitive to the inertia coefficient J than the VSG, and that a serious power oscillation may occur. According to this, a new rotor model is designed to make the inertial coefficient automatically change to adapt to the operating state. Experimental results show that the PV-VSG control strategy can achieve stable operation and maximum power output when the PV output power is insufficient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.4
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• pp.8-15
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• 2000

In this paper, we realize the active PFC(Power Factor Correction) system of BF(Boost Forward) converter with PWM-PFM(Pulse Width Modulation-Pulse Frequency Modulation) control technique to control DC output voltage, to remove the noise like harmonics at output voltage, and to control the input current with sinusoidal wave synchronized by the source voltage.To achieve the desired load voltage and improved PFC, we first implement current shaping control at the inverting stage and make the converted output DC voltage with forward converter. After making the ratio of output voltage to current as 50V/1A and the duty ratio greater than 0.5. When input voltage is 30V and boost inductance is 1.1mH. we control the voltage changing rate according to the variation of load resistance using a PWM-PFM control technique. And finally we prove experimentally, we attenuated its harmonics and improved PF up to 0.96 using the current shaping technique.

• Journal of Power Electronics
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• v.16 no.6
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• pp.1991-2004
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• 2016

An LC filter is required to reduce the output current ripple in the auxiliary resonant snubber inverter (ARSI) for high-performance applications. However, if the traditional control method is used in the ARSI with LC filter, then unnecessary current flows in the auxiliary circuit. In addressing this problem, a novel load-adaptive control that fully uses the filter inductor current ripple to realize the soft-switching of the main switches is proposed. Compared with the traditional control implemented in the ARSI with LC filter, the proposed control can reduce the required auxiliary current, contributing to higher efficiency and DC-link voltage utilization. In this study, the detailed circuit operation in the light load mode (LLM) and the heavy load mode (HLM) considering the inductor current ripple is described. The characteristics of the improved ARSI are expressed mathematically. A prototype with 200 kHz switching frequency, 80 V DC voltage, and 8 A maximum output current was developed to verify the effectiveness of the improved ARSI. The proposed ARSI was found to successfully operate in the LLM and HLM, achieving zero-voltage switching (ZVS) of the main switches and zero-current switching (ZCS) of the auxiliary switches from zero load to full load. The DC-link voltage utilization of the proposed control is 0.758, which is 0.022 higher than that of the traditional control. The peak efficiency is 91.75% at 8 A output current for the proposed control, higher than 89.73% for the traditional control. Meanwhile, the carrier harmonics is reduced from -44 dB to -66 dB through the addition of the LC filter.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.204-205
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• 2016

Human power is not dependent on other energy sources, but rather is a source of power for ourselves. Human power, the cleanest energy in the world, can be our future. Therefore, we should be interested in sustainable alternative energy. This paper solves the uneven power generation by utilizing the energy storage capability of the flywheel. Therefore, it improved the efficiency by 5% compared to the existing generation method. DC generators produce power at variable speed operation. The constant voltage was generated from the DC-DC converter to the duty ratio control. Therefore, the charging efficiency is improved by 5% by the constant voltage charging of the battery. And it can suppress the decrease of the output due to the circulation current due to the deviation of the output voltage in parallel operation of the pedal generator.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.220-227
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• 2009

A self oscillation DC/DC converter which has a very desirable characteristics of the high input-output voltage conversion ratio for high voltage DC power supply applications is proposed in this paper. The proposed converter is composed of one power switch, one inductor, several capacitors and diodes. Compared with conventional high-voltage DC/DC converters, it performs the high- voltage power conversion using the inductor instead of the bulky step-up transformer. Therefore, it can reduce the size of magnetic device and save the cost. Moreover, since it needs no control IC by using self oscillation circuit and has lower voltage stress on output diodes, it features a lower cost, simpler structure and more improved performance. Finally, a comparative analysis and experimental results are presented to show the validity of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.2
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• pp.124-132
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• 2014

In this paper, we implement a non-time-varying transfer function of the duty ratio to improve the control characteristics in a control system that Input voltage and the output voltage is varied, DC / DC converters for bi-directional charging. When control is performed with using controller gain of conventional design, characteristics of the control is varied to fluctuations of the input voltage. The proposed method is the equivalently removing method for duty ratio in entire control block, by voltage controller gain is changed for inverse of the duty ratio. The proposed non-time-varying duty ratio transfer function is applied to DC / DC converter for bi-directional charging. In this paper, feasibility and superiority is verified through PSIM simulations and experiments.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.235-241
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• 2013

A low power CMOS control circuit is applied in an integrated DC-DC buck converter. The integrated converter is composed of a feedback control circuit and power block with 0.35 ${\mu}m$ CMOS process. A current-sensing circuit is integrated with the sense-FET method in the control circuit. In the current-sensing circuit, a current-mirror is used for a voltage follower in order to reduce power consumption with a smaller chip-size. The N-channel MOS acts as a switching device in the current-sensing circuit where the sensing FET is in parallel with the power MOSFET. The amplifier and comparator are designed to obtain a high gain and a fast transient time. The converter offers well-controlled output and accurately sensed inductor current. Simulation work shows that the current-sensing circuit is operated with an accuracy of higher than 90% and the transient time of the error amplifier is controlled within $75{\mu}sec$. The sensing current is in the range of a few hundred ${\mu}A$ at a frequency of 0.6~2 MHz and an input voltage of 3~5 V. The output voltage is obtained as expected with the ripple ratio within 1%.

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.66-70
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• 2000

This paper deal with a design and a constant output power control of Zero Current Zero Voltage Switching(ZCZVS) resonant type DC-DC converter by a digital I-PD phase shift controller. When the DC-DC converter for a high density and a high effect control is operated in high speed switching, the switching loss and switching stress of the switching devices are increased. So, the ZCZVS method, which has the phase shift control with the digital I-PD controller, must be use in order to reduce its. And the constant output power voltage that controlled by the digital I-PD controller tracks a reference without steady state error in variable input voltage. The validity of control strategy that proposed is verified experimental results by the Digital Signal Processor TMS320C32.