Virtual Admittance Reshaping Based Ripple Current Suppression Strategy of DC-Link Capacitors for PMSM Drives

In single-phase input permanent magnet synchronous motor (PMSM) drives, the dc-link electrolytic capacitors exhibit low tolerance to second-harmonic ripple current (SHRC). This limitation hinders further enhancements in system reliability and power density. Therefore, a ripple current suppression strategy of dc-link capacitors based on virtual admittance reshaping is proposed. The second-harmonic ripple characteristics of dc-link capacitors are characterized through admittance analysis. Based on system admittance modeling, a virtual path for the SHRC is established by paralleling admittance. In this way, the suppression degradation caused by the bandwidth limitation of traditional strategies can be mitigated. Moreover, the SHRC suppression rate is derived from the constant thermal power. On this basis, the virtual admittance parameters are designed, and the sensitivity is analyzed. The proposed strategy requires no additional hardware and exhibits low parameter sensitivity. Finally, the effectiveness of the proposed strategy is verified on the experimental platform with dc-link capacitance reduced by 70%.