On efficient variable voltage linear power supplies

The computer aided design of variable voltage, single-phase, linear power supplies using an SCR bridge is discussed. The effects of transformer leakage reactance, resistance, filter capacitance, the low power integrated circuit voltage regulator and the current boost circuit used to increase output power from such supplies is taken into account in the design. By controlling the firing angle of the SCR bridge, the resultant linear supply is more energy efficient in power conversion than the traditional diode bridge based linear power supply. The increase in amplitude of the low frequency harmonics in the line current of the SCR bridge based supply is quantified vis-á-vis the diode bridge based supply. A prototype SCR bridge based design is used to experimentally validate the design computations. An implementation of a controller to operate the SCR bridge based supply efficiently is discussed.