Autonomous refrigeration plant powered by photocells driving DC motor - uses array of photo voltaic cells to supply differentially compound DC motor having dominant series characteristic to give steady torque

摘要

The plant has its compressor driven by a differentially compounded DC motor powered from an array of photo-voltaic cells. A refrigerated storage is incorporated to maintain cooling when illumination of the photo-cells is low. The best efficiency is obtained if the DC motor maintains a near constant torque output despite the varying voltages output from the photocell array which, once loaded, behaves as a current source, resulting in wide voltage fluctuations with little change in current. The use of a DC machine, differentially compounded to have a dominant series characteristic, results in a near constant torque output despite a wide voltage range. The photo-cells are arranged to provide a fairly high voltage and comparatively low current. The compressor is of the piston type and is driven at constant torque.