AC “Back to Back” Switching Device in Industrial Application

In industrial applications, among several varieties of semiconductor devices available, a silicon-controlled rectifier (SCR) is often used in managing and protecting various systems with different applications. Hence, it is of the utmost importance to design a control system which can operate over a range of electrical loads without any modifications in its hardware and/or software. This paper analyzes and investigates in detail the power circuit effects on conduction delay and SCR functioning. Moreover, two different commonly used driving systems for SCR application have been introduced, discussed, and evaluated. Concerning driving systems, here, three aspects have paramount importance and are consequently taken into consideration, namely the driver system losses, the conduction delay, and in particular, some power quality indices. The conduction delay is a parameter of great importance, as being able to control and reduce it to the minimum allowed by the application can bring significant practical advantages (both in terms of application and economic terms, as better summarized in the article). Theoretical analysis has been performed, followed and verified by simulation studies and, for some cases, laboratory experimental test results are presented which provide credibility to the study.