Characterization and Application of a Pseudorandom Impulse Sequence for Parameter Estimation Applications

Wideband perturbation signals are commonly used in system identification applications to ensure that all relevant dynamic modes of a system are persistently excited. Controllability of the signal's frequency content is highly desirable so that perturbation energy can be focused in a targeted frequency band. In high-power applications, it is furthermore important to efficiently generate a signal with suitable voltage and current levels and apply it in situ. This article proposes the novel concept of a bipolar pseudorandom impulse sequence (PRIS) as a wideband perturbation signal for in situ application in the power applications. A circuit topology is proposed for generating a PRIS signal. The circuit design considerations for the proposed PRIS source are discussed, and it is shown that the PRIS can be generated using a compact and efficient design with highly reduced average power losses compared to conventional sources such as the pseudorandom binary sequence (PRBS) current source and a PRBS voltage source connected through a series resistor. The time- and frequency-domain characteristics of the PRIS are reviewed, and it is demonstrated, through mathematical analysis and simulations, that the frequency spectrum of the PRIS perturbation signal can be controlled by manipulating the associated PRBS clock frequency and time constants of the impulse waveforms. Experimental results are presented to demonstrate the performance of the PRIS perturbation system for estimating the impedance spectrum of a complex Thevenin source in the presence of harmonic voltage distortion. The results show that the PRIS waveform performs very well in this in situ application.