A modified cross-correlation method for the identification of systems with large bandwidth

On-line system identification is generally used to find the mathematical or frequency model of a system for control applications. In particular, the cross-correlation technique is nowadays used for nonparametric identification of linear or linearized systems such as switching power converters. This method is however limited to systems with close time constants, therefore, it cannot be applied to systems with different time constants in a large bandwidth, such as machine drives. This paper presents a modified cross-correlation method. It first provides an improved calculation technique for the parameters of the pseudo-random binary signal used as input signal for identification. It then modifies the initial cross-correlation technique allowing the identification of systems with different time constants in a large bandwidth. Simulation results using MATLAB/Simulink validate the feasibility of the proposed technique in order to implement it using FPGAs.