Hybrid Voltage Vector Based Model Predictive Control With Flux-Weakening Function for Dual Three Phase PMSM Drives

Abstract

Although the field-oriented control (FOC) with flux-weakening (FW) function has been investigated in dual-three-phase (DTP) PMSM drives, the research on model predictive control (MPC) with FW is few. In this paper, the MPC with FW and using hybrid voltage vector (VVs) is proposed. To avoid overmodulation when using FOCs with FW, a margin needs to be kept in the voltage constraint of FW or constraints needed to be applied on the z₁z₂ voltage reference. In contrast, in the proposed hybrid MPC both the margin and the constraints are freed with sequential optimization, resulting in larger torque-speed operation range and lower current THD. In addition, hybrid VVs are used in the proposed MPC. Two long VVs are used for αβ regulation per control cycle, which increases the torque-speed operation range, while two z₁z₂ virtual VVs are used for z₁z₂ regulation, which ensures high z₁z₂ harmonic suppression capability. The VVs are selected based on voltage reference estimation for light computation burden, while their duty ratios are calculated by the projected quadratic programming (QP) algorithm for the same reason. With the proposed hybrid MPC, wider torque-speed operation range and lower current distortion can be obtained, compared with the traditional MPC using virtual VVs and FOC with FW. Finally, experiments are conducted to verify the feasibility and advantages of the proposed method.