1. Introduction

The development of industrial automation leads by default also to the improvement of electrical drive systems as more than these systems represent the most spread conversion type of the electrical energy in the mechanical energy.

Hereby, by an adequate command given by a controller into a close circuit, the static converters adjust the output electrical energy parameters, to the necessity demand by an electrical motor.

The static switch controllers are converters where the exit size has the same form with the entry size. By changing the control angle of the converter thyristor is obtained a variation of the effective/average value of the output voltage [2, 3].

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