Doo-Yong Jung

A Real Maximum Power Point Tracking Method for Mismatching Compensation in PV Array Under Partially Shaded Conditions

Conventional popular maximum power point tracking (MPPT) methods are effective under uniform solar irradiance. However, under solar irradiance mismatching conditions [partially shaded conditions (PSCs)], these MPPTs can fail for real MPPT (RMPPT), because multiple local maxima can be exhibited on the power-voltage characteristic curve. Although some researchers have worked on RMPPT under partial shading conditions, the methods have some drawbacks in terms of complexity and requirements for additional circuits, etc. In this paper, a novel MPPT method capable of RMPPT under PSCs is proposed. The performance of the proposed MPPT method is analyzed according to the RMPP position and is verified by simulation and experimental results.

Interleaved Soft-Switching Boost Converter for Photovoltaic Power-Generation System

In this paper, a interleaved soft switching boost converter (ISSBC) for a photovoltaic (PV) power-generation system is proposed. The topology used raises the efficiency for the dc/dc converter of the PV power conditioning system (PVPCS), and it minimizes switching losses by adopting a resonant soft-switching method. A detailed mode analysis of the proposed topology is presented. The feasibility of the proposed topology is experimentally verified for a 1.2-kW prototype. The experimental results imply that 97.28% efficiency is achieved under the full-load condition. Consequently, it is confirmed that the overall efficiency is increased by about 1.5% compared with the conventional hard switching interleaved boost converter.

Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their surface characteristics

Transparent conductive, undoped and aluminum-doped ZnO (AZO) thin films were prepared on the glass substrates at deposition temperature in the range of room temperature (R.T.) ;300 8C by RF magnetron sputtering. Highly oriented AZO films in the w002x direction were obtained with specifically designed ZnO targets. A systematic study on the dependence of deposition parameters on the structural, optical and electrical properties of the as-grown AZO films was mainly investigated in this work. The AZO film prepared at R.T. with 4 wt.% Al(OH) doped a ZnO target under a target-to-substrate distance (D ) of 3 ts

Maximum power point tracking method for PV array under partially shaded condition

Conventional popular MPPT methods are effective under uniform solar irradiance. However, under partially shaded conditions, these MPPTs can fail to track the real MPP because of the multiple local maxima which can be existed on PV characteristic curve under partially shaded condition. In spite of some researchers have worked on real MPP tracking under partial shading conditions, the methods have some drawbacks with complexity and requirement of additional circuit, etc. In this paper, a novel MPPT method that is capable of tracking the real MPP under partially shaded conditions is proposed. The performance of proposed MPPT is analyzed according to the position of real MPP and is verified by simulation and experimental results.

Dual mode switching strategy of flyback inverter for photovoltaic AC modules

In recent years, many topologies have been developed as PV module integrated converter for AC module system. Among these topologies, the flyback-type power converter have been occupied the attention due to its simplicities on configuration and control. In this paper, dual mode switching control method for flyback-type PV module integrated converter is proposed. Proposed switching control method changes the mode of operation in DCM and BCM alternatively. It is expected that the high performances in efficiency and transferred power quantity can be achieved through the conduction mode change. The efficacies of proposed switching technique are validated by simulation and experimental result.

Soft-Switching Bidirectional DC/DC Converter with a LC Series Resonant Circuit

In this paper, a soft-switching bidirectional dc/dc converter with a LC series resonant circuit is proposed. The proposed converter has been obtained by adding LC series resonant tank in the conventional bidirectional dc/dc converter. The proposed topology performs soft switching at both buck and boost operations. Through the theoretical boost and buck mode analysis, zero voltage switching operation is explained. Moreover, characteristics of the proposed topology are verified with simulation and experimental results.

Soft switching boost converter for photovoltaic power generation system

In this paper, a soft switching boost converter for solar power system is proposed. It is a topology, which raises efficiency for DC-DC converter of photovoltaic PCS (power conditioning system). And it minimizes switching losses by adopting soft switching method using resonance. It analyzes the operation characteristic of topology which was suggested through simulation, and proves the validity by analyzing loss and efficiency at real operation with experiment.

Auxiliary Switch Control of a Bidirectional Soft-Switching DC/DC Converter

In this paper, the auxiliary switch control using a lookup table is proposed to enhance the efficiency of the bidirectional dc/dc converter used in electric vehicle, which performs soft switching. Continuous current data are difficult to obtain during a resonant operation due to the limit of DSP ADC capacity. The proposed auxiliary switch control has a lookup table reference of the auxiliary switch turn-on time. The control method properly controls the auxiliary switch turn-on time according to the required load current; this auxiliary switch control brings the more efficient control in generative and regenerative mode operation. The proposed approach has been validated by the results of experiments on a bidirectional dc/dc converter, inverter, and interior permanent magnet synchronous motor.

A current shaping method for PV-AC module DCM-flyback inverter under CCM operation

In the grid interconnected photovoltaic power generation system including PV-AC module system, the output current have to be sinusoidal synchronized with the grid voltage. Concerning the voltage-controlled current-source modification requirement and the characteristics of flyback topology, boundary or discontinuous conduction mode operations are suitable for the PV-AC module flyback inverter. However, the flyback inverter can be operated in continuous conduction mode (CCM) due to its operating conditions in spite of it is designed to operate under boundary or discontinuous conduction mode. Unfortunately, it causes unintended distortion to output current. In this paper, a current shaping method to reduce the output current distortion for the DCM-flyback inverter is proposed. Even though the flyback inverter operates under CCM, the output current distortion can be reduced by the unfolding H-bridge switching technique.

A soft switching boost converter using an auxiliary resonant circuit for a PV system

This paper proposes a soft switching boost converter using an auxiliary resonant circuit for a PV system. The topology is composed of a general boost converter adding an auxiliary resonant circuit which has a switch, inductor, capacitors and diode. The auxiliary resonant circuit helps the main switch operate with ZCS and ZVS. And the auxiliary switch also operates with ZVS. ZVS and ZCS techniques enable to reduce switching losses and improve the efficiency of the system. The theoretical analysis is verified through simulations and experiments. The perturbation and observation algorithm is applied for this system. Experimental results are obtained from the 1kW prototype. Efficiencies by the variable duty and load are measured through the experiment.