Reduced Spread Fractional-Order PID Controller Designs

A fractional-order controller topology for solving the problem of the extremely large spread of passive elements values, when the order of the required integration and/or differentiation approaches unity, is presented in this work. This is achieved through the decomposition of the corresponding process into intermediate parts, containing an integer-order and a reduced-order fractional part. The resulting functional block diagram is implemented using Operational Amplifiers as active cells. The provided controller design example proves the concept through simulation results derived using the OrCAD PSpice emulator and using the model of the OP27 operational amplifier discrete IC component.