A Novel Deep Flux Weakening Control Strategy for IPMSM

To realize the smooth transition from the partial flux weakening zone I (FW-I Zone) to the deep flux weakening zone II (FW-II Zone) and avoid the current loop saturation during the deep flux weakening control for an interior permanent magnet synchronous motor (IPMSM), a novel deep flux weakening control method is proposed to implement variable direct axis (d-axis) current limitations strategy (VDL-FWC). On the basis of the traditional voltage closed-loop feedback regulation flux weakening control (FB-FWC) strategy, the d-axis flux weakening current is limited by the maximum torque per voltage (MTPV), which is quickly obtained through a parabolic approximation that varies with the quadrature axis (q-axis) current. Therefore, when the d-axis weakening current exceeds its limitation, a closed-loop voltage feedback proportional-integral controller is used to adjust the q-axis current increment, which transfers the exceeding d-axis current to the q-axis current to prevent voltage saturation. The proposed deep flux weakening control strategy is compared with the FB-FWC strategy. Studies show that the proposed strategy is effective, which can smoothly transition to the deep flux weakening zone avoiding running out of control.KeywordsFlux weakening controlInterior permanent magnet synchronous motor (IPMSM)Improved maximum torque per voltage (IMTPV)