Han Zhang

Space vector modulation (SVM) provides good dynamic control for surface-mounted permanent magnet synchronous machine (SPMSM) drives by realizing reference voltage or flux in each time step. However, high-speed SPMSM drives can suffer from significant switching-induced harmonic distortions due to high electrical frequencies and low carrier ratios. Harmonic-optimized pulse width modulation (PWM) methods like synchronous optimal modulation (SOM) minimize current total harmonic distortion (THD) through offline-optimized pulse patterns (OPPs), but they have poor dynamic response. This paper proposes a fast dynamic current control method for high-speed SPMSM drives that addresses these limitations. The proposed method tracks the optimal flux trajectory (OFT) under low pulse number conditions via space vector synthesis, using optimal switching vector patterns (OSVPs) derived from SOM rather than conventional 7- or 5-section SVM patterns. Hence, this method synergistically combines the advantages of both SVM and SOM, achieving fast current tracking (within 1/6 of an electrical cycle) during transients, while minimizing current THD in steady-state conditions. Additionally, the method is simple, avoiding complex flux observers and high control frequencies, while compensating for control delay and machine parameter uncertainties. Experiments on a prototype high-speed SPMSM drive with pulse numbers ranging from 3 to 15 confirm the method's effectiveness.

Inaccurate motor parameters can lead to deterioration of the control system performance of permanent magnet synchronous motor (PMSM). In order to mitigate the adverse control outcomes caused by inaccurate motor parameters and the impact of these parameters on model predictive current control, in this article, a predictive current error compensation-based strong robust model predictive control (PCEC-MPC) for PMSM drive systems is proposed. This method does not require accurate motor parameters. Instead, perturbation terms of inductance, resistance, and flux-linkage are designed to replace the motor parameters, and then the expression equations of the perturbation terms are obtained by constructing the predictive current error compensation controller. Besides, a balancing factor is introduced to equalize the impact of both current and perturbation terms on the predictive model. Finally, the feasibility of the proposed method is verified experimentally.

Zero-sequence current (ZSC), which inherently exists in the open-winding permanent magnet synchronous motor (OW-PMSM) with a common dc bus, would deteriorate the control performance of the system and add additional losses. Conventional proportional-integral (PI) controller involves the simultaneous adjustment of several parameters, which is an extremely time-consuming process. To solve these problems, this article proposes a simple deadbeat predictive current control (DPCC). First, a reference voltage weight factor is designed to redistribute the reference voltage of the dual-inverter, which makes the zero-sequence voltage generated by the nonzero voltage vector (VV) and the third harmonic back electromotive force cancel. Consequently, ZSC can be completely suppressed. Second, the zero VV u ₇ (111) are excluded from the modulation, so the switching frequency of the dual-inverter and common mode voltage can be effectively reduced. Meanwhile, the effective modulation range is analyzed in this article, which reveals the relationship between the ratio of the third harmonic flux linkage and the modulation index. Finally, the effectiveness and advantages of the proposed method are verified on a 1.25-kW OW-PMSM experimental platform.

To improve the control performance of open- winding permanent magnet synchronous motor (OW-PMSM) and suppress zero-sequence current (ZSC), this article proposes a hybrid vector model predictive control (MPC) for OW-PMSM drives. The fast-voltage-vector selection strategy is used to select one optimal non-zero voltage vector (VV) to act on inverter1 (INV1) for each control period, and then inverter2 (INV2) is controlled with a novel four-segment-mode-vector (FSMV) control strategy to operate the dual-inverter separately. In this strategy, the two zero VVs, u ′ ₀ and u ′ ₇ , are applied at the starting and ending of each control period alternately, while two adjacent non-zero VVs, u ′ _x and u ′ _y , with minimum switching times are applied in the middle of the control period to generate PWM pulses with a switching frequency fixed at half of the control frequency. Furthermore, the durations of two zero VVs ( u ′ ₀ and u ′ ₇ ) are optimized to suppress the ZSC based on the 0-axis current deadbeat (DB) control principle. Finally, the experimental findings suggest that the proposed strategy ensures the low switching frequency of INV1 and the fixed switching frequency of INV2 to obtain good control performance.

To address the zero-sequence current (ZSC) suppression and high switching frequency problems of open-winding permanent magnet synchronous motor (OW-PMSM) prediction control while improving the operation performance of the system, a novel bilateral four-segment-mode model predictive current control (MPCC) scheme for OW-PMSM drives is proposed in this article. In each control period, four voltage vectors (VVs) are applied to the dual-inverter, two null VVs U ₀ / U ₇ and U′ ₀ / U′ ₇ are alternated at the beginning and end of each period, and two active VVs are acted in the middle of the control period with the minimum switching action to generate PWM pulses. As a result, a lower and fixed switching frequency could be obtained, which is half of the control frequency. In addition, the duration of two null VVs U′ ₀ and U′ ₇ in inverter2 (INV2) is optimized to suppress ZSC based on the deadbeat control principle of 0-axis current. Finally, an experimental platform with a 1.25-kW OW-PMSM demonstrates that the proposed scheme achieves a lower switching frequency of the dual-inverter, while the control performance of the system is improved.

A novel dual four-stage-vector model predictive control (MPC) strategy for open-winding permanent magnet synchronous motor (OW-PMSM) drives is put forward in this article. In each control period, four vectors, including two non-zero vectors and two zero vectors, are applied to the dual-inverter. According to the principle of minimum number of switches, two non-zero vectors are applied in the middle of the control period, while the two zero vectors are distributed at the beginning and the ending of the control period, significantly reducing the control frequency. In addition, two zero vectors of inverter2 (INV2) are optimally distributed to inhibit the flow of zero-sequence current (ZSC). Therefore, the ZSC of the system is well-suppressed. Finally, compared to the conventional strategy, the control performance of the proposed strategy is proved by an experimental platform with a 1.25kW OW-PMSM.