This paper proposes a novel maximum-power-point tracking (MPPT) method with a simple algorithm for photovoltaic (PV) power generation systems. The method is based on use of a short-current pulse of the PV to determine an optimum operating current where the maximum output power can be obtained and completely differs from conventional hill-climbing-based methods. In the proposed system, the optimum operating current is instantaneously determined simply by taking a product of the short-current pulse amplitude and a parameter because the optimum operating current is exactly proportional to the short current under various conditions of illuminance and temperature. Also, the system offers an identification capability of by means of fast power-versus-current curve scanning, which makes the short-current pulse-based MPPT method adaptive to disturbances such as shades partially covering the PV panels and surface contamination. The above adaptive MPPT algorithm has been introduced into a current-controlled boost chopper and a multiple power converter system composed of PV-and-chopper modules. Various operating characteristics have experimentally been examined on this multiple PV-and-chopper module system from a practical viewpoint and excellent MPPT performance has been confirmed through the tests.Index Terms-Current-controlled chopper, maximum-powerpoint tracking, multiple module system, photovoltaic, short-current pulse.

This paper focuses on a maximum power point tracking method of photovoltaics by means of use of the short-current pulse. It has been reported that the optimum operating current is proportional to the short current and the maximum power point tracking can be performed by detecting the short current. The pro posed method utilizes the intermittent short-current pulse to estimate the optimum operating current and its operating characteristics have experimentally been verified. Also, an adaptive mechanism to identify the parameter between the optimum current and the short current is discussed. A prototype of the controller has been set up and the experimental results have demonstrated excellent performance, which proves feasibility of the system. 78T.

This paper proposes a novel maximum-powerpoint tracking (MPPT) method with a simple algorithm for photovoltaic (PV) power generation systems. The method is based on use of a short-current pulse of the PV to determine an optimum operating current for the maximum output power and completely differs from conventional hill-climbing based methods. In the proposed system, the optimum operating current is instantaneously determined by taking a product of the short-current pulse amplitude and a parameter k because the optimum operating current is exactly proportional to the short current under various conditions of illuminance and temperature. Also, the system offers an identification function of k by means of fast power-vs.-current curve scanning, which makes the short-current pulse based MPPT adaptive to disturbances such as shades partially covering the PV panels. The above adaptive MPPT algorithm has been adopted to a current-controlled boost chopper and a multiple power converter system composed by PV-chopper modules. Various operating characteristics have been examined, and excellent MPPT performance has been confirmed through the experimental tests.

SUMMARYThis paper focuses on a maximum-power-point tracking method of photovoltaics via use of the short-current pulse. It has been reported that the optimum operating current is proportional to the short current and that maximum-power-point tracking can be performed by detecting the short current. The proposed method utilizes the intermittent short-current pulse to estimate the optimum operating current and its operating characteristics have experimentally been verified. Also, an adaptive mechanism to identify the parameter between the optimum current and the short current is discussed. A prototype of the controller has been set up and the experimental results have demonstrated excellent performance, proving the feasibility of the system. ©

By using the electric-field-induced optical second-harmonic generation (EFISHG), we measured the EFISHG-time (EFISHG-t) characteristics to study pre-electrical breakdown of indium-zinc-oxide (IZO)/ N,N'-di [(1-naphthyl)-N,N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine (-NPD)/ tris(8-hydroxy-quinolinato)aluminum(III) (Alq3)/Al organic light-emitting diodes (OLEDs). A series of EFISHG pulses were identified as a pre-electrical breakdown phenomenon, before OLEDs were electrically broken. Analyzing the results revealed the additional negative charge accumulation at the -NPD/Alq3 interface which caused by the generation of EFISHG pulses. We concluded that the EFISHG-t measurement is available as a method for detecting pre-electrical breakdown phenomena of OLEDs.