B-spline based repetitive controller revisited: Error shift, higher-order polynomials and smooth pass-to-pass transition

The paper presents a modified version of a training algorithm for a B-spline network (BSN). The algorithm is used as a controller for a constant-amplitude constant-frequency voltage-source inverter (CACF VSI) with an LC output filter. The modification is divided into three parts. Firstly, there are B-spline functions of higher orders that are used especially functions of a second order. Secondly, the B-spline functions are described in cyclic manner which allows to achieve smooth control signal in steady state. Last modification involves introduction of a shift between the error and the control signal. It improves convergence of the algorithm and allows to achieve a long term stability without using the forgetting factor.