Variable speed motor drive testing and parameter identification using pseudorandom binary sequences

Normal and inverse repeat pseudorandom binary sequences (PRBS) are very effective as persistent excitation stimuli in dynamic testing and parameter extraction in motor drive systems. In general a simple linear time invariant (LTI) second order transfer function model can he deployed in conjunction with PRBS correlation methods for adjustable speed drive (ASD) parameter identification. Very accurate parameter extraction from correlation based impulse response evaluation is achieved using data training records from pseudonoise (pN) testing, in both the online and off-line mode of operation of a PWM controlled variable speed DC motor drive system. The alternative approach of motor parameter extraction from spectral analysis, based on sinusoidal test signals, is used for comparison purposes as a secondary check on the effectiveness and accuracy of the PBBS method and to validate the LTI model used.