• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.464-470
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• 2015

In this paper, a non-isolated three-level high step-up boost converter with output voltage balancing is proposed. By adding one extra inductor to the conventional three-level boost converter, the proposed converter is derived. Compared with the traditional boost converter and the three-level boost converter, the proposed converter can obtain very high voltage conversion ratio, and the voltage and current stress of switching devices and diodes are reduced. A 2.7 kW prototype converter is built and tested to verify performances of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.96-105
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• 2021

Large-scale power converters consist of series or parallel module combinations. In these modular converter systems, the interleaving technique can be applied to improve capacitor reliability by reducing the ripple of the I/O current in which each module operates as a phase difference. However, when applying the interleaving technique for conventional three-level boost converters, the short-circuit period of the converter can be an obstacle. Such problem is caused by the absence of a low-level inductor of the conventional three-level boost converter. To solve this problem, a three-level boost converter with a low-level inductor is proposed and analyzed to enable interleaved operation. In the proposed circuit, the current ripple of the output capacitor depends on the neutral point connections between the modules. In this study, the ripple current is analyzed by the neutral point connections of the three-level boost converter that has a low-level inductor, and the effectiveness of the proposed circuit is proven by simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.40-46
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• 2018

In this study, the output voltage balancing characteristics of parallel-input series-output (PISO) boost converter is analyzed. The PISO boost converter is derived by combining two basic boost converters. In comparison with the conventional three-level boost converter, the PISO boost converter can balance the output voltages under an unbalanced load condition without requiring additional circuit components and control strategy. A 2 kW prototype converter is built and tested to verify the output voltage balancing characteristics of the PISO boost converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.127-132
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• 2020

In this study, single-phase and three-level boost converters applied to the photovoltaic system were compared and analyzed in terms of efficiency and power density according to the input voltage and load conditions. For accurate analysis of efficiency, the losses in each device of the single-phase and three-level boost converters were derived using mathematical equations and simulations by using the PSIM thermal module. Then, the losses were compared with the efficiency confirmed through the actual experiments. Results confirmed that the efficiency and power density can be improved by applying the three-level boost converter to the system according to the selection of the switching frequency.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.269-278
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• 2020

In this paper, two types of DC/DC converters in a hydrogen fuel cell hybrid railway vehicle system, which serve to charge high-voltage battery and supply power to an inverter for driving a driving motor, were compared and analyzed. A two-level interleaving boost converter and a three-level boost converter were compared and analyzed, and a theoretical design method was proposed to have an efficiency characteristic of over 95%. In addition, a digital controller design method considering the digital phase delay component of DSP (TMS320F28335) is presented. Finally, the validity of the theoretical design of the converter with 20kW power was verified through static and dynamic experiments respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1481-1486
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• 2013

The small wind generator with existing mechanical control system has a frequent failure and malfunction, and its maintenance is difficult. In this paper, an electric control method using a boost converter for small wind generator was suggested. The suggested 2-level boost converter control device was manufactured and its experimental operation were conducted on a wind generator with 200 [W] capacity. As a result of experimental device, the control by a boost converter was executed at the point that the output voltage of a wind generator became 36 [V] so it could be identified that the output voltage of a wind generator diminished and then it became 0 [V] after 5 [sec]. Besides, in case of applying the method suggested in this paper to a small wind power generation facility for street lights, it is expected to reduce its maintenance by preventing a frequent failure of a generator and to improve its utilization rate.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.271-279
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• 2015

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of $V_{DC}$, one more $V_{DC}$ is derived using buck-boost converter giving $2V_{DC}$ as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of $2V_{DC}$ and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.133-141
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• 2020

The use of high-gain-voltage step-up converters for distributed power generation systems is being popularized because of the need for new energy generation and power conversion technologies. In this study, a new constructed high-gain-boost DC-DC converter was proposed to coordinate low voltage output DC sources, such as PV or fuel cell systems, with high DC bus (380 V) lines. Compared with traditional boost DC-DC converters, the proposed converter can create higher gain and has wider input voltage range and lower voltage stress for power semiconductors and passive elements. Moreover, the proposed topology produces multilevel DC voltage output, which is the main advantage of the proposed topology. Steady-state analysis in continuous conduction mode of the proposed converter is discussed in detail. The practicability of the proposed DC-DC converter is presented by experimental results with a 300 W prototype converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.36-43
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• 2017

This paper describes a hybrid multi-output three-level DC/DC converter suitable for a wide, high-input voltage range of an auxiliary power supply for a high-power photovoltaic generating system. In a high-power photovoltaic generating system, the solar panel output voltage depends on solar radiation quantity and varies from 450Vdc to 1100Vdc. The proposed hybrid multi-output three-level DC/DC converter, which is an auxiliary power supply, would be used as power source for control printed circuit boards and relay and cooling fans in a high-power photovoltaic generating system. The proposed multi-output ($24V_{DC}/30A$, $230V_{DC}/5A$) hybrid three-level boost converter, which uses an energy recovery snubber, is controlled by variable-frequency and phase-shifted modulations and can achieve zero-voltage switching with all operating conditions of input voltage and load range. Experimental results of a 2kW prototype are evaluated and implemented to verify the performance of the proposed converter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.16-26
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• 2014

This paper proposes new 13-level inverter topology and DC/DC converter buck-boost structure topology for multilevel, compounding uni-directional and bi-directional switches, and proposes high-efficient multilevel inverter system in which the proposed two PCS(Power Conditioning System) was connected in series. In proposed multilevel inverter of forming a output 13-level phase voltage by using total 18 switching parts, Then bi-directional switch has a characteristic of reducing conduction loss and controlling the reactive power effectively by separating electrically from the neutral point. DC/DC converter for supplying in dependent 3 DC voltage to the proposed multi-level inverter generates 180-degree phase shifted PWM by the symmetrically combined structure of 2 buck-boost converter and twice switching frequency efficiency can be obtained, meanwhile, the converter can step up/down the output voltage and 20% output can be generated comparing the input voltage. This proposed system is verified with the simulation and laboratory test.