Enhancement of Disturbance Rejection Capability in Dual Three-Phase PMSM System by Using Virtual Impedance

Dual three-phase permanent magnet synchronous machine systems usually suffer from small impedance to voltage disturbance such as inverter voltage errors and back EMF harmonics. This article proposes a virtual impedance technique to increase the machine equivalent impedance and, thus, enhance the disturbance rejection capability of the system. This enhancement can contribute to current harmonic suppression in a wide range of frequencies. In addition, the introduction of virtual impedance can also reduce the system sensitivity to parameter variation, which helps to suppress the dynamic current overshoot, pulsating, and cross-coupling effect caused by the parameter mismatch. Simulation and experimental results have verified the effectiveness of the proposed control strategy.