Applications of ripple correlation control of electric machinery

Ripple correlation control can be applied to electric drive systems in order to optimize some cost function independent of parameters. This involves correlating the perturbations in the cost function with the perturbations in the independent variable to obtain a command for the independent variable. The perturbations are normally due to ripple that is naturally present in electric drive systems. In the steady state, the fast-average value of the independent variable converges asymptotically to a point no more than the magnitude or the ripple away from the optimum set point. In certain applications, cost function observers must be created to obtain the correct correlation information. In this paper, ripple correlation control is developed and demonstrated for DC, induction, and brushless DC drives.