• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.425-432
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• 2020

The phase-shifted, full-bridge (PSFB) DC-DC converter is widely used in electric vehicles (EVs) to charge a low-voltage (12 V) battery from a high-voltage battery. A Photovoltaic (PV) module-integrated PSFB converter is proposed for the EV power conversion system. The converter is useful because solar energy can be utilized to extend the driving range. The buck converter circuit is simply realized by adding one switch to the conventional PSFB converter's secondary side. For the inductor and diode, the existing components in the PSFB converter are shared. The proposed converter can charge a low-voltage battery from the PV module with maximum power point tracking. In addition, the two power sources can be used simultaneously, and efficiency is increased by reducing the circulating current, which is a problem for the conventional PSFB converter.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1217-1226
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• 2015

In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.25-31
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• 2007

In this paper, a novel MPPT(Maximum Power Point Tracking) algorithm for power of PV(Photovoltaic) systems is presented using a boost converter for a connected single phase inverter. On the basic principle of power generation for the PV(photovoltaic) module, the model of a PV system is presented. On the basis of this model, simulation of this PV system and algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT#s switch in full bridge. Furthermore, a low cost control system for solar energy conversion using the DSP is developed, based on the boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.471-477
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• 2012

In this paper, in order to use module integrated converter using cascaded buck-boost converter for a low battery charger in stand-alone system, a charging algorithm which considers photovoltaic and battery status and PWM controllers which are changed according to charging modes are proposed. The proposed algorithm consists of constant current mode, constant voltage mode and maximum power point tracking mode which enables the battery to charge with maximum power rate. This paper also presents design of cascaded buck-boost converter that is the photovoltaic charger system. A 150W prototype system is built according to verify proposed the charger system and the algorithm.

• Journal of the Korean Solar Energy Society
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• v.29 no.6
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• pp.1-13
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• 2009

Photovoltaic conditioning systems normally use a maximum power point tracking (MPPT) technique to deliver the highest possible power to the load continuously when variations occur in the insolation and temperature. A unique method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these points is presented through deriving small-signal model and transfer function of boost converter considering input capacitor. This paper aims at modeling boost converter including fairly large equivalent series resistance(ESR) of input reservoir capacitor by state-space-averaging method and PWM switch model and compares both methods using Bode plots. In the future, properly designed controller for compensation will be constructed in 3kw real system for maximum photovoltaic power tracking control.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.437-442
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• 2002

This paper presents a current-source-inverter based on a buck-boost configuration md its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150[W] prototype equipped with digital signal processor TMS320F241.

• Journal of the Korean Solar Energy Society
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• v.28 no.5
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• pp.85-95
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• 2008

Photovoltaic conditioning systems normally use a maximum power point tracking (MPPT) technique to deliver the highest possible power to the load continuously when variations occur in the insolation and temperature. A unique method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these points is presented through deriving small-signal model and transfer function of boost converter considering input capacitor. This paper aims at modeling boost converter including fairly large equivalent series resistance(ESR) of input reservoir capacitor by state-space-averaging method and PWM switch model. In the future, properly designed controller for compensation will be constructed in 3kw real system for maximum photovoltaic power tracking control.

• Journal of Power Electronics
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• v.19 no.4
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• pp.1011-1019
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• 2019

In this paper, a buck-flyback (fly-buck) stand-alone photovoltaic (PV) system for charge balancing with a differential power processor (DPP) circuit is proposed. Conventional feed-back DPP converters draw differential feed-back power from the output of a string converter. Therefore, the power is always through the switches and diodes of the string converter. Because of the returning conduction path, there are always power losses due to the resistance of the switch and the forward voltage of the diode. Meanwhile, the proposed feed-back DPP converter draws power from the magnetically-coupled inductor in a string converter. This shortens the power path of the DPP converter, which reduces the power losses. In addition, the extra winding in the magnetically-coupled inductor works as a charge balancer for battery-stacked stand-alone PV systems. The proposed system, which uses a single magnetically-coupled inductor, can control each of the PV modules independently to track the maximum power point. Thus, it can overcome the power loss due to the power path. It can also achieve charge balancing for each of the battery modules. The proposed topology is analyzed and verified using 120W hardware experiments.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1191-1192
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• 2006

This paper propose method of maximum power point tracking using boost converter for a connected single phase inverter. The maximum power point tracking control is based on generated circuit control MOSFET switch of two boost converter and single phase inverter uses predicted current control to control four IGBT's switch in full bridge. The predicted current control provide current with sinusoidal wave shape and inphase with voltage.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.70-71
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• 2017

This paper presents a new cascaded boost multilevel converter topology for distributed generation (DG) systems. Most of DG systems, such as photovoltaic (PV), wind turbine and fuel cells, normally require the complex structure power converters, which makes the system expensive, complex and hard to control. However, the proposed converter topology can generate a much higher output voltage just by using the standard low-voltage switch devices and low voltage DC-sources in a simplified structure, also enhancing the reliability of the switch devices. Simulation and experimental results with a 1.2kW system are presented to validate the proposed topology and control method.