A Novel Pole-Separation-Based Gain Calculation Method for High-Pass Filtered Damping Control in <i>LCL</i>-Equipped High-Speed PMSM Drives

For LCL-equipped high-speed permanent magnet synchronous machines, inverter-current-feedback active damping control without additional sensors is preferred, but the active damping coefficients are difficult to select by solving the characteristic roots of a four-order system (considering the digital delay). In this paper, an innovative pole-separation gain selection method is proposed to ensure the stability of the LCL resonance within the Nyquist frequency. Consequently, a very simplified analytical expression between the system parameters and the active damping coefficients is concluded. Finally, the effectiveness of the proposal is validated by driving the tested motor with a rated fundamental frequency of 1.2 kHz. The experimental stable range of the coefficients is consistent with the theoretical analysis based on the proposed gain selection method.