High Performance Multi-Sampled Control for Power Electronics Converters

This article presents a review of multi-sampled pulse-width modulation (MS-PWM), where feedback sampling, control execution, and modulating signal update are performed more than twice per modulation period. Consequently, this modulation strategy enables very fast dynamic performance, robust stability, and noise suppression in two-level, multi-level, and interleaved power electronics converters. First, small-signal models are presented to show the positive impact of MS-PWM on delay reduction. Reduced modulation delay allows for an increase of the control loop bandwidth and higher disturbance rejection, which is demonstrated with several application examples including impedance-based stability of grid-connected converters. Next, nonlinear effects that may arise with MS-PWM due to the switching ripple content in the feedback signal are analyzed and some measures for their suppression are presented. Finally, the capabilities of MS-PWM to strongly attenuate white and switching noise, while preserving fast dynamic performance, are analyzed. Thereby, various linear and non-linear feedback filtering methods are discussed. Numerous experimental validations, performed on different setups with two-level and multi-level converters, are provided to support the analyses.