The Influence of Switching Frequency on Outer and Inner Control Loops of PMSM Based on Frequency Response Identification

摘要

This paper establishes the mathematical model of control loops of permanent magnet synchronous motor (PMSM), considering the switching frequency of the inverter. While choosing appropriate coefficients of the PI regulator, it is indicated that the cut-off frequency of the current loop is approximately proportional to the switching frequency, with enough phase margin. But in a specific range, the switching frequency has less impact on the cut-off frequency of speed loop, which is in connection with the inertial time constant of PMSM. Meanwhile, specific adaptive noise canceling is used by the least mean square algorithm, frequency response of control loops can be identified online. The simulation and experimental results confirm the validity of the new proposed identification method and the mathematical model of control loops.