Impressed current cathodic protection is widely used to prevent corrosion of structural steels. The major constituents, which accelerate corrosion, are resistivity, chlorides, sulfatesand the acidity (pH) of the soil. Because of these variations, the transformer-rectifier units must control and tune the output voltage depending on desired reference voltage steadily. Usually, classical controls such as PI and PID, have been widely used with their gains manually tuned based on the desired reference voltage. But, classical controls require different gains at the lower and higher end of the output voltage range to avoid overshoot and oscillation.