Power Generation of Pure Sine Wave in Batteryless Solar System using Advanced Control

A novel technique for conversion of DC power to AC power is introduced using solar powered sine wave generation system is presented. DC power extracted from solar system is made utilitarian for driving the BLDC (brushless DC) motor with constant speed constraints. The back EMF signals of each phase of the BLDC motor facilitated the development of technique for the sine wave generation from solar system without battery backup. This motor is coupled with AC generator, which yields the AC power on demand. The constant speed constraint indispensable for fixed electrical frequency at the output of generator. A new control technique is rendered for reference tracking speed control of BLDC motor using Lyapunov theory by changing switching frequency, and also maintaining the voltage level at the output of converter driving BLDC by regulating the switching frequency of the zeta converter. The proposed methodology for generation of AC power from solar power system is also tested on prototype. The comparison of conventional technique for generation of sine wave power and proposed scheme is mentioned at later section of this paper for describing the efficacy of newly presented scheme.

Seasonal Variations in Some Physiological Responses of Maize Zea Mays L. under Glasshouse Conditions

In view of the changing climatic conditions mainly related to greenhouse effect, this study was focused on determining the responses of two differentially heat tolerant maize varieties to glasshouse condition. The parameters studies included growth, water relations, gas exchange, photosynthetic pigments, oxidative damage and gene expression. Results revealed that prevailing glasshouse conditions played a crucial role in affecting the maize growth across winter and summer seasons. Despite differences in the growing seasons and varieties glasshouse conditions were adverse for the photosynthetic systems in maize. Major yardsticks of sensitivity were loss of chlorophyll and carotenoids in the light reactions, while reductions in the net photosynthesis and stomatal conductance in the glasshouse grown maize. Prevailing glasshouse conditions were greatly effective in hampering the leaf water relation particularly those of winter sown crop. The glasshouse conditions in winter crop produced oxidative stress on the plants, which was explicit from the increased synthesis of H 2 O 2 , MDA and increased permeability to the ion leakage. Greater free proline accumulation in the tolerant variety not only presented itself as a major amino acid accumulated in environmental stress tolerance but also indicated it as a reliable indicator of tolerance to glasshouse condition in maize. With great varietal difference, changes of temperature and relative humidity inside the glasshouse across the seasons were mainly responsible for the observed changes in mineral nutrients. More distinct changes were evident in K, Ca and nitrate nutrition, which were given greater credence in view of their closer association to the seasonal changes in the environmental conditions inside the glasshouse. Maize seedlings showed sensitivity to high temperature stress, which was recorded from morphological (reduction in shoot fresh weight, dry weight of shoot and root and a reduction in fresh-to-dry weight ratio) and gene expression patterns. The molecular studies suggested that the maize sensitivity to high temperature was mainly due to enhanced coexpression of sag and dhn2 and failure to express hsp70 and sgr2 during relatively long term exposure to high temperature.