An enhanced discrete virtual vector- based direct torque control (DTC) strategy is proposed in this article to improve the steady state performance of permanent magnet synchronous motor (PMSM). Discrete virtual vectors are synthesized to extend the candidate voltage vector set, and a universal method is put forward to take advantage of the extended voltage vector set. Three groups of parallel lines, each group perpendicular to one of the A, B, C axes, are carefully designed to divide the internal region of the vector hexagon into several regular subregions, and each subregion has exactly one voltage vector in the center. Conveniently, if the reference voltage vector is located within a certain subregion, the voltage vector located in the corresponding subregion is selected, and the vector selection table is accordingly established. The proposed strategy maintains the simple control structure and good dynamic performance of DTC, and improves the steady state performance by reducing torque ripple and current distortion compared with the existing DTC methods with discrete space vector modulation. Experiments verified the effectiveness of the proposed DTC strategy.

In order to solve the problem that the position synchronous performance of dual permanent magnet synchronous motor servo system is easily affected by parameter perturbation and load disturbance, an anti-disturbance integrated position synchronous control strategy of dual permanent magnet synchronous motor system is proposed. Firstly, the integral mathematical model of a dual permanent magnet synchronous motor system is established. After that, the third-order linear extended state observer is constructed to observe and compensate for disturbance in order to improve the anti-disturbance performance of the position loop. At the same time, a cross-coupled position synchronous compensator is added to improve the synchronous performance of the system, and through the Bode diagram analysis method in the frequency domain, the system stability and anti-disturbance performance are researched. Finally, the effectiveness of the proposed algorithm is verified by experimental research.

In this paper, the characteristics of the voltage transfer ratio (VTR) and low-order harmonics of the major modern space vector overmodulation strategies for two-level PWM converters are discussed under different VTRs, and the complexity of the modulation algorithm is subsequently elaborated. First, the principles of these overmodulation strategies are summarized. After that, the accuracy and linearization of the VTR are obtained using the Fourier transform analysis, and the relationship between the main low harmonic components and the VTR is obtained in the same way. All the analysis results are verified through experiments. In addition, the merits and demerits of these overmodulation strategies and applications are revealed by comparing the simplicity of their modulation algorithm, digitization, and other characteristics. Finally, this paper reveals the essence of space vector overmodulation strategies. The results facilitate the design, performance prediction, and development of high-performance overmodulation strategies, as well as the transplantation of space vector overmodulation strategies into different converter topologies.

Model predictive control (MPC) mitigates synchronous error accumulation, dynamic response mismatch, and precision-complexity tradeoff in traditional multimotor system. However, constrained numerical solutions in MPC present significant computational challenges. To address this, this article proposes a predictive position synchronization control strategy based on geometric constraints for dual permanent magnet synchronous motor (PMSM) system. First, an incremental MPC framework is constructed, whose embedded integral action not only effectively compensates for short control horizons but also enables high-precision multistep prediction. Second, a cost function incorporating tracking error, synchronous error and control increment is established to derive the current control increment. To reduce computational complexity, a constrained geometric mapping method is proposed: with control horizon N_c = 1, current and voltage constraints are mapped to a 2D plane to form a feasible region, converting the optimal control increment solution into determining the tangent point between the cost function’s elliptic surface family and this feasible region. Rapidly localizing the tangent via real-time query and calculation of analytical solutions significantly reduces online computational load. Experimental results show the proposed strategy can improve computational efficiency by approximately 47% and dynamic response speed by approximately 57% versus traditional quadratic programming (QP) strategy, resolving the precision-complexity tradeoff in multimotor synchronization while ensuring accuracy.