Transformer-Less Grid Voltage Controller Through SCR Switches and a Flexible Pulse Device

This study includes detailed steps of design and implementation of a wide-range grid voltage controller for application with DC and AC loads. The proposed controller offers a transformer-less function, which reduces the size of the controller. It is implemented using SCR switches controlled by a flexible pulse generator. The pulse generator is capable of producing trigger pulses of controllable widths for successfully switching on the controller’s SCRs. Within the pulse generator, a cascade of operational amplifier stages in various configurations is used to generate the firing pulses. Furthermore, an alternating voltage of 230 V/50 Hz is used from the grid to supply the controller. Thus, a wide range of AC load voltage from 0 V to 230 V is generated. This voltage is rectified in the case of a DC load. The system is first simulated, then practically implemented to validate the design of the controller. The test results reflect the capability of selecting suitable duration of firing pulses to guarantee SCR toggling. The presented solution is highly promising for varying AC and/or DC load voltages.