Direct on line starting induction motor with Thyristor Switched Capacitor based voltage regulation

Thyristor switched capacitor banks is a mature issue, but a low cost optical triacs with a built in zero-crossing function may reduce the cost of such application. The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors (TSC) as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are presented.