Abstract: The present invention relates to a speed control system for hermetic compressors of the variable speed type, which uses a PMSM motor, containing a strategy for optimization, or minimization, of the electric current. Once the minimum current has been defined to meet a given demand for torque, it is applied to the hermetic compressor motor, which will operate at the maximum efficiency point for each load point.

Abstract: A resistive thermostat for Motors protection against electrical overcurrents and overtemperature, having a rectangular prismatic body, with a front side cover, and a back side face being provided with a corner lowering having a spherical sector shape, as well as a pair of thin rectangular windows, the rectangular body forming an enlargement of its front edge for fitting of the cover, from which a lower tab is appended, having a locating end cutout with reference to two pins of a three-pins connection plug; and further; inside the prismatic box, corresponding to the pair of thin side windows, it is provided an end pair of metallic supports for an electrical resistor, wherein one of such support projects a balanced metallic blade outside the box, including one of its connection terminals, while in the other inner support having a C shaped attached to the end of the balanced bimetallic blade, immediately subjacent and connected in series with the electrical resistor and with the lower opposite and free end of th