A hybrid flyback LED driver with utility grid and renewable energy interface
In renewable energy sources, the objective is maximum extraction and utilization of the available power. In this paper a hybrid flyback converter with multi ports-an AC Grid, a PV and a DC LED ports — is proposed to be used as an LED driver. The converter has the capability to achieve two objectives: first to maintain a continuous supply to the LED lighting system either from the Photovoltaic (PV) panel or the grid, and second to achieve maximum utilization of the solar PV panel by tracking the maximum power point and exporting surplus power to the grid, or getting the power deficit from the grid. The topology of the converter, operating principle, modes of operation and control structure are presented in this work. The concept of the hybrid flyback converter is verified using Matlab Simulink®. An experimental prototype is developed and tested for a 120-watt system, with 35 VDC solar panels, 120 Vrms 60 Hz grid and 24 VDC LED lights.
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.
Experimental study of thermal modeling for stratospheric platform airships
R&D work on the Japanese stratospheric platform airship is discussed from the viewpoint of the thermal modeling. The work includes two experiments on the thermal characteristics of the 25m-long airship and the 35m-long PV-equipped airship model. The validity of the current thermal model was confirmed by comparing the calculated results with the measured data. The other important work is the Ground-to-Stratosphere (GTS) flight test. A 47mlong airship-shaped balloon was flown to the stratosphere. The flight simulation program into which the thermal model was integrated, was developed and applied successfully to predict the ascent behavior and the flight trajectory.