• Journal of Power Electronics
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• v.7 no.2
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• pp.124-131
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• 2007

In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM resonant DC-DC converter with two simple auxiliary commutation lossless inductor snubbers is presented. The operation principle of this converter is described using the switching mode equivalent circuits. This newly developed multi resonant DC-DC converter can regulate its DC output AC power under a principle of constant frequency edge-resonant soft switching commutation by an asymmetrical PWM duty cycle control scheme. The high frequency power regulation and actual power characteristics of the proposed soft switching PWM resonant DC-DC converter are evaluated and discussed. The operating performances of the newly proposed soft switching inverter are represented based on simulation results from an applications point of view.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1402-1412
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• 2017

This paper presents a new high step-up dc/dc converter for renewable energy systems in which a high voltage gain is provided by using a coupled inductor. The operation of the proposed converter is based on a charging capacitor with a single power switch in its structure. A passive clamp circuit composed of capacitors and diodes is employed in the proposed converter for lowering the voltage stress on the power switch as well as increasing the voltage gain of the converter. Since the voltage stress is low in the provided topology, a switch with a small ON-state resistance can be used. As a result, the losses are decreased and the efficiency is increased. The operating principle and steady-states analyses are discussed in detail. To confirm the viability and accurate performance of the proposed high step-up dc-dc converter, several simulation and experimental results obtained through PSCAD/EMTDC software and a built prototype are provided.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.541-549
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• 2014

In this paper, an extended switched-inductor quasi-Z-source inverter (ESL-qZSI) with high boost voltage inversion ability is presented, which combines the SL-qZSI with the traditional boost converter, as well as improves the switched-inductor cell. Compared with the classic qZSI topologies, the proposed topology reduces the voltage stresses of capacitors, power devices and diodes for the same input and output voltage. Furthermore, the conversion efficiency is improved. The operation principle of the proposed topology is analyzed in details, which is followed by the comparison between the three topologies. In addition, the performance of the proposed topology is verified by simulations and experiments.

• Journal of Power Electronics
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• v.16 no.1
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• pp.277-286
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• 2016

This paper offers two Maximum Power Point Tracking (MPPT) systems for Photovoltaic (PV) applications. The first MPPT method is based on a fixed frequency Model Predictive Control (MPC). The second MPPT technique is based on the Predictive Hysteresis Control (PHC). An experimental demonstration shows that the proposed techniques are fast, accurate and robust in tracking the maximum power under different environmental conditions. A DC/DC converter with a high voltage gain is obligatory to track PV applications at the maximum power and to boost a low voltage to a higher voltage level. For this purpose, a high gain Switched Inductor Quadratic Boost Converter (SIQBC) for PV applications is presented in this paper. The proposed converter has a higher gain than the other transformerless topologies in the literature. It is shown that at a high gain the proposed SIQBC has moderate efficiency.

• Journal of Power Electronics
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• v.15 no.3
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• pp.587-601
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• 2015

A high step-up dc-dc converter is proposed for photovoltaic power systems in this paper. The proposed converter consists of an input current doubler, a symmetrical switched-capacitor doubler and an active-clamp circuit. The input current doubler minimizes the input current ripple. The symmetrical switched-capacitor doubler is composed of two symmetrical quasi-resonant switched-capacitor circuits, which share the leakage inductance of the transformer as a resonant inductor. The rectifier diodes (switched-capacitor circuit) are turned off at the zero current switching (ZCS) condition, so that the reverse-recovery problem of the diodes is removed. In addition, the symmetrical structure results in an output voltage ripple reduction because the voltage ripples of the charge/pump capacitors cancel each other out. Meanwhile, the voltage stress of the rectifier diodes is clamped at half of the output voltage. In addition, the active-clamp circuit clamps the voltage surges of the switches and recycles the energy of the transformer leakage inductance. Furthermore, pulse-width modulation plus phase angle shift (PPAS) is employed to control the output voltage. The operation principle of the converter is analyzed and experimental results obtained from a 400W prototype are presented to validate the performance of the proposed converter.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1187-1194
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• 2017

In this paper, a high step-up DC-DC PWM converter with continuous input current and low voltage stress is presented for renewable energy application. The proposed converter is composed of a boost converter integrated with an auxiliary step-up circuit. The auxiliary circuit uses an additional coupled inductor and a balancing capacitor with voltage doubler and switching capacitor technique to achieve high step-up voltage gain with an appropriate switch duty cycle. The switched capacitors are charged in parallel and discharged in series by the coupled inductor, stacking on the output capacitor. In the proposed converter, the voltage stress on the main switch is clamped, so a low voltage switch with low ON resistance can be used to reduce the conduction loss which results in the efficiency improvement. A detailed discussion on the operating principle and steady-state analyses are presented in the paper. To justify the theoretical analysis, experimental results of a 200W 40/400V prototype is presented. In addition, the conducted electromagnetic emissions are measured which shows a good EMC performance.

• Journal of IKEEE
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• v.23 no.3
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• pp.1054-1060
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• 2019

A extension of the high boost voltage-lift DC-DC converter with large conversion ratio has been proposed in this paper. The proposed extension is combined the switched-inductor cell (SL-cell) and modular voltage cell (MV-cell). The proposed structure can achieve the large voltage conversion without high duty-cycle and the low voltage of the components. Moreover, the PID controller for novel SL-MV voltage-lift DC-DC converter also introduces. This technique a good-performance output voltage can kept constant with an good transient performance when the output load is suddenly changed. In order to prove the theoretical analysis, the experimental setup has been built for the DC load of $150[{\Omega}]$ and $300[{\Omega}]$. In addition, the transient of output voltage has been tested to determine the controller. Experimental results validate the effectiveness of the theoretical analysis proving the satisfactory converter performance.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.484-489
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• 2020

This study proposes a new soft-switching three-level flying capacitor converter with low filter inductance. The proposed converter can achieve zero voltage switching (ZVS) turn-on of all switches by using auxiliary components La and Ca. It can also reduce filter inductance because the applied voltage of the filter inductor is decreased by using the flying capacitor. Furthermore, filter inductance can be reduced because the operating frequency of the filter inductor is doubled by the phase shifting between switches S3 and S4. The operation principle, design of passive components for ZVS turn-on, interleaving effects, and comparison of different topologies are presented. The experimental waveforms of a 1 kW two-phase interleaved converter prototype are provided to verify the validity of the proposed converter.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1629-1638
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• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.1 no.1
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• pp.38-46
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• 1996

The commutation operation of the current source converter for switched reluctance motor drives is analyzed in this paper. The commutation operation in the current source converter consists of two modes. At turn-off of phase switch, the phase current decreases sinusoidally, and the sum of two phase currents during commutation period is constant. At this time, the capacitor voltage increases quickly with changing polarity and decreases slowly when another phase switches turn on or off. Frequency of step-down DC chopper in the current source converter is low because of the dump such as BJTs and GTOs are possible as phase switches instead of Power MOSFET and IGBTS. They may result in reductions of conduction losses and manufacturing cost in the current source converter comparing to the voltage source converter of SRM.