• Journal of Advanced Engineering and Technology
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• v.5 no.4
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• pp.349-353
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• 2012

Recently, Mobile multimedia equipments as smart phone and tablet pc requirement is increasing and this market is also being expanded. These mobile equipments require large multi-media function, so more power consumption is required. For these reasons, the needs of power management IC as switching type dc-dc converter and linear regulator have increased. DC-DC buck converter become more important in power management IC because the operating voltage of VLSI system is very low comparing to lithium-ion battery voltage. There are many people to be concerned about digital DC-DC converter without using external passive device recently. Digital controlled DC-DC converter is essential in mobile application to various external circumstance. This paper proposes the DC-DC Buck Converter using the AVR RISC 8-bit micro-processor control. The designed converter receives the input DC 18-30 [V] and the output voltage of DC-DC Converter changes by the feedback circuit using the A/D conversion function. Duty ratio is adjusted to maintain a constant output voltage 12 [V]. Proposed converter using the micro-processor control was compared to a typical boost converter. As a result, the current loss in the proposed converter was reduced about 10.7%. Input voltage and output voltage can be displayed on the LCD display to see the status of the operation.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.225-231
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• 2013

Low voltage ride through capability augmentation of a hybrid micro-grid system is presented in this paper which reflects enhanced reliability in the system. The control scheme involves parallel connected multiple ac-dc bidirectional converters. When the micro-grid system is subjected to a severe voltage dip by any transient fault single power converter may not be able to provide necessary reactive power to overcome the severe voltage dip. This paper discusses the control strategy of additional power converter connected in parallel with main converter to support extra reactive power to withstand the severe voltage dip. During transient fault, when the terminal voltage crosses 90% of its pre-fault value, additional converter comes into operation. With the help of additional power converter, the micro-grid system withstands the severe voltage fulfilling the grid code requirements. This multiple converter scheme provides the micro-grid system the capability of low voltage ride through which makes the system more reliable and stable.

• Journal of Power Electronics
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• v.5 no.4
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• pp.247-256
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• 2005

In order to harvest power in an efficient manner from a micro piezoelectric (PZT) device for charging the battery of a remote system, a new AC/DC resonant pulse power converter is proposed. The proposed power converter has two stages in the power conversion process. The first stage includes N-type MOSFET full bridge rectifier. The second stage includes a boost converter having an N-type MOSFET and a P-type MOSFET. MOSFETs work in the $1^{st}$ or $3^{rd}$ quadrant region. A small inductor for the boost converter is assigned in order to make the size of the power converter as small as possible, which makes the on-interval of the MOSFET switch of the boost converter ultimately short. Due to this short on-interval, the parasitic junction capacitances of MOSFETs affect the performance of the power converter system. In this paper, the performance of the new converter is analytically and experimentally evaluated with consideration of the parasitic capacitance of switching devices.

• Journal of Power Electronics
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• v.8 no.2
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• pp.156-162
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• 2008

This paper proposes a low-cost power converter for micro wind turbine systems using permanent magnet synchronous generators (PMSG). The proposed converter consists of a two-leg three-phase PWM inverter for the generator control and a single-phase half-bridge PWM converter which is connected to the utility grid. For the two separate DC-link voltages, a balancing control is added and the adverse effect of the DC-link voltage ripples on the inverter output voltage is compensated. The control performance of the proposed converter topology for the micro wind turbine system is shown by the simulation results using PSIM software.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.560-565
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• 2011

This paper proposes the design of micro energy harvesting system by using thermoplastic polyurethane(TPU), which harvests electric energy from the kinetic energy of pedestrian and drives the desired load, and applied it to the self-generating shoes. Also, we designed the buck-boost converter in discontinuous conduction mode(DCM) which functions as a resistor emulator(RE) such that converter's average input current is proportional to input voltage, and it results in transfer of maximum power to buck-boost converter according to control behavior that converter's input resistance is matched with TPU's internal resistance. Therefore, this paper confirms the validity of proposed control scheme and possibility of application for self-generating shoes, from the obtained characteristic of designed micro energy harvesting system by using a TPU and buck-boost converter in DCM.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.2
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• pp.157-163
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• 2014

This paper proposes a two-stage step-down buck and a tapped-inductor boost cascaded converter for high efficiency photovoltaic micro-inverter applications. The proposed inverter is a new structure to inject a rectified sinusoidal current into a low-frequency switching inverter for single-phase grid with unity power factor. To build a rectified-waveform of the output current. the converter employs both of a high efficiency step-up and a step-down converter in cascade. In step-down mode, tapped inductor(TI) boost converter stops and the buck converter operates alone. In boost mode, the TI converter operates with the halt of buck operation. The converter provides a rectified current to low frequency inverter, then the inverter converts the current into a unity power-factor sinusoidal waveform. By applying a TI, the converter can decrease the turn-on ratios of the main switch in TI boost converter even with an extreme step-up operation. The performance validation of the proposed design is confirmed by an experimental results of a 120W hardware prototype.

• Journal of IKEEE
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• v.18 no.1
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• pp.159-164
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• 2014

This paper targets the development of micro-converter such as a power converter for photovoltaic module. In corresponding to the poor performance of centralized PV system under partial shading, the power converter for single PV module to maximize the energy harvest from PV module. The power converter is constantly tracking the maximum power point of photovoltaic system and increases energy output power. To minimize the quantity of devices and switchs, 320W solar micro-converter is developed using synchronous rectifier. From the basis of these results, through simulations and experiments were verified efficiency.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.44-45
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• 2011

Research on photovoltaic (PV) generation is taking a lot of attention due to its infinity and environment-friendliness with decrease of price per PV cell. While central inverters connect group of PV modules to utility grid in which maximum power point tracking (MPPT) for each module is difficult, micro inverter is attached on each module so that MPPT for individual modules can be easily achieved. Moreover, energy generation and consumption efficiency can be much improved by employing direct current (DC) distribution system. In this paper, a digitally controlled PV micro converter interfacing PV to DC distribution system is proposed. Boundary conduction mode (BCM) is utilized to achieve zero voltage switching (ZVS) of active switch and eliminate reverse recovery problem of passive switch. A 120W prototype boost PV micro converter is implemented to verify the feasibility and experimental results show higher than 98% efficiency at peak power and 97.29% of European efficiency.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.563-573
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• 2007

Optimal design of an automotive catalytic converter for minimization of cold-start emissions is numerically performed using a micro genetic algorithm for two optimization problems: optimal geometry design of the monolith for various operating conditions and optimal axial catalyst distribution. The optimal design process considered in this study consists of three modules: analysis, optimization, and control. The analysis module is used to evaluate the objective functions with a one-dimensional single channel model and the Romberg integration method. It obtains new design variables from the control module, produces the CO cumulative emissions and the integral value of a catalyst distribution function over the monolith volume, and provides objective function values to the control module. The optimal design variables for minimizing the objective functions are determined by the optimization module using a micro genetic algorithm. The control module manages the optimal design process that mainly takes place in both the analysis and optimization modules.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.813-814
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• 2009