In this paper, nine, seven, five and three level diode clamped multilevel inverters (9L-7L-5L-3L DCMI) have been designed and used in wind generation system. The DCMI is designed to operate at low switching frequency with low THD by increasing the number of output voltage levels. The proposed designed DCMI is then connected to permanent magnetic synchronous generator (PMSG) wind turbine to generate an AC output voltage. A low switching frequency sinusoidal pulse width modulation (SPWM) triggering circuit is adopted as the controlling signals. Several cases were studied with varying number of levels and/or modulation indices used. The overall system is modeled in MATLAB/Simulink and a satisfied result be obtained.

There is no adopt in the importance of the optical communications in scientific civil and military applications because of it’s simplicity in manufacturing and it's low cost. The method of optical communication depends upon bearing the light beam the translated informations by a method called the light modulation. This method depends upon changing some light properties as frequency, amplitude and pulse duration according to the translating informations. The changes in the first two properties are concerned optically with the analog modulation while the third one concern at most with digital modulation. All past methods are expensive with low efficiency and needs electrical or magnetic fields. In this technique the source of voice used a source of emitting light at the same time. This was done by using a reflecting microphone to reflect the incident laser beam to the receiver which was an photocell which connected to an audio amplifier. The emitting voice was clear without any type of noise with very high efficiency.