Dual three-phase permanent magnet synchronous machines (DTP-PMSMs) have received increasing attention from the industry and academia due to their advantages in lower burden on power inverters when operating in high power applications compared to the three-phase counterparts and low torque ripples. In this article, it reveals that the favorable low torque ripple characteristic of DTP-PMSM is undermined in the high power and overload operating mode. To solve this problem, this article proposes a novel torque ripple suppression strategy based on optimal harmonic current injection. A mathematical torque ripple model of DTP-PMSM considering the cross-coupling effects between d–q axis and dq - z ₁ z ₂ axis is built. And based on this model, a detailed analysis is carried out to obtain the optimal harmonic current. The theoretical analysis also guarantees that the induced machine loss is minimum. Moreover, the proposed strategy has good dynamic performance since the algorithm involves no iterative computation and is computationally effective, which is proved on a laboratory DTP-PMSM system. The effect of parameter variation is also discussed and tested. The experiment results prove that the influence of magnetic saturation on torque ripple can be effectively suppressed.

Carrier frequency current harmonic peaks induced by pulsewidth modulation (PWM) in motion control systems will cause high-frequency torque ripple, efficiency decrease, and electromagnetic interference problems. It is proved in this article that carrier-frequency harmonic current components in dual three-phase permanent magnet synchronous motor (DTP-PMSM) systems exhibit a different distribution and are more severe compared to the three-phase ones due to the existence of the low-impedance harmonic subspace, thereby limiting the further application of DTP-PMSMs. To address this issue, this article proposes an advanced carrier phase-shift modulation strategy. First, by introducing a π /2 phase shift between two PWM modules, the dominating first carrier frequency harmonic current components in z ₁ – z ₂ subspace are halved. The high-frequency torque ripple, located at second carrier frequency, is also suppressed. Periodic frequency modulation is utilized in the proposed strategy to further suppress the high-frequency harmonic current components in both α – β and z ₁ – z ₂ subspaces. The effectiveness of the proposed strategy is demonstrated theoretically and verified by simulation and experiments. DC-link current can also benefit from the proposed strategy. Compared with conventional space vector pulsewidth modulation (SVPWM) and random SVPWM, the proposed strategy has a better harmonic suppression effect without inducing distortion.

This paper proposed an open-circuit fault-tolerant control method for dual three-phase permanent magnet synchronous motor (DTPPMSM), which takes the back electromotive force (back EMF) harmonics into consideration and can achieve the minimum torque ripple. From the perspective of machine ontology and electromagnetic power, this paper analyzed the influence of back EMF harmonics on torque ripple. On this basis, by adjusting the phase of currents, specific order torque ripple components which can offset each other can be generated by the back EMF fundamental wave and harmonics, thus suppressing the specific order torque ripple of the whole motor. Furthermore, not limited to specific order torque ripple, the method can also be used to obtain the minimum overall torque ripple under open-circuit operation. Finite element analysis (FEA) and prototype experiment are employed to verify the proposed method.

This article proposes a novel Laguerre function-based long-horizon constrained model predictive direct speed control strategy (CMP-DSC-Laguerre) for permanent magnet synchronous motor (PMSM) speed control. Compared with the traditional model predictive control (MPC) procedure, the introduction of Laguerre function parameterization reduces the computational burden, making long-horizon MPC feasible in real applications without compromising the system’s performance. The proposed design enables easier solutions to long prediction horizon MPC problems while improving system stability and speed control performance in both transient and steady states. Furthermore, the proposed controller intuitively incorporates a one-step-ahead control generation method to compensate for the time-delay effect in digital PMSM control systems. The resultant current and voltage constraints are modeled for the first time, and the control signal is then obtained by solving the corresponding optimization problem. Experimental validation of the proposed method shows its effectiveness and feasibility compared to conventional cascaded proportional–integral (PI) control, direct predictive speed control, and popular full cascaded MPC methods.

Due to stator magnetic saturation and inherent cogging torque, the slotted limited angle torque motor (LATM) performs large torque ripple within its operation range, resulting in vibration noise and complex control problem. The novelty of this paper is to not only firstly apply 1J22 soft magnetic alloy (SMA) in the LATM, but also propose a multi-objective optimization method to improve torque performances including torque ripple, cogging torque, and output torque, based on genetic algorithm (GA). Firstly, 1J22 soft magnetic alloy is applied to LATM to reduce the torque ripple caused by magnetic field saturation. Then, through the sensitivity analysis, weight coefficients of the related parameters of stator tooth, needed for the optimization process, are obtained. Besides, in order to optimize the torque performances, the multi-objective optimization process is carried out, and the GA is used to obtain the desired objective. Finally, the finite element analysis (FEA) is used to validate the optimization design.

Dual three-phase permanent magnet synchronous motor (DTPPMSM) can realize low-voltage high-power drive, fault tolerant operation, and presents lower torque ripple. To comprehensively describe the electromagnetic characteristics of DTPPMSM, this paper proposed a high-precision model of the machine. The proposed model is established based on the flux linkage extracted via finite element analysis (FEA), which can take into account the cross coupling effect, the electromagnetic coupling between the two sets of three-phase windings, the nonlinearity caused by magnetic saturation, the influence of harmonic magnetic field and rotor position. The model is established based on the existing FEA results and interpolation, no more calculation is required during the running, so the model has both high-precision and fast calculation speed. The accuracy and feasibility of the proposed model are verified by experimental results.