Analog Fractional Order Controller in Temperature and Motor Control Applications

An analog fractional order PI λ controller, using a circuit element with fractional order impedance, a Fractor (patent pending), is demonstrated in both a simple temperature control application and a more complex motor controller. The performance improvement over a standard PI controller was notable in both reduction of overshoot and decreased time to stable temperature, while retaining long term stability. In the motor controller, set point accuracy was considerably improved over conventional control. The modification of the standard controller to a fractional order controller was as simple as replacing the integrator capacitor with a Fractor. Mixing (i.e., hybridization) of digital and analog control was demonstrated.