The present paper describes a low power (750 W) switched reluctance motor drive for home appliances featuring close to unity power factor and low cost. The key features of the proposed drive are a simple speed control, minimum switch number inverter topology, and a compact high quality rectifier (HQR) input stage based on a quasi-resonant boost topology. The obtained structure is suitable for integration and allows to develop an inexpensive chip implementing all the main functions required by the proposed drive. The paper starts by pointing out recently introduced constraints on line current pollution of home appliances. The proposed drive is then presented emphasizing the design of the high quality rectifier input stage. Experimental results on a prototype are finally presented to evaluate the efficiency of the proposed drive.

Introduction: Winter pruning is a cultivation practice necessary for maintaining the balance between the vegetative and the productive activity of plants and requires many working days using hand scissors. This operation involves the subjects carrying out a series of gestures that are repeated...

Radiometric calibration of multispectral imagery plays a critical role in the determination of vegetation-related features. This radiometric calibration strongly depends on a proper sensor configuration when acquiring images, the shutter speed being a critical parameter. The objective of the present study was to appraise the influence of shutter speed on the reflectance in the visible and near-infrared (NIR) spectral regions registered by a low-cost multispectral sensor (MAPIR Survey3) on a homogeneous field of turfgrass (Cynodon dactylon L.—Poaceae) and on the vegetation index (VI) values calculated from them, under different solar radiation conditions. For this purpose, 10 shutter speed configurations were tested in field campaigns with variable solar radiation values. The main results demonstrated that the reflectance in the green spectral region was more sensitive to shutter speed than that of the red and NIR spectral regions, particularly under high solar radiation conditions. Moreover, VIs calculated using the green band were more sensitive to slow shutter speeds, thus presenting a higher probability of providing meaningless artifact values. In conclusion, this study provides shutter speed recommendations under different illumination conditions to optimize the reflectance and the VI sensitivity within the image, which can be applied as a simple method to optimize image acquisition from unmanned aerial vehicles under varying solar radiation conditions.