This article investigates the application of star-delta hybrid concentrated-winding (CW) in permanent magnet vernier machines (PMVMs), with main focus on power factor and field-weakening capability. The analysis results show that the hybrid CW exhibits low-coupling property, namely both the mutual inductances between the comprising coils of each single phase and that among three-phase windings are eliminated. As a result, the q-axis flux linkage and required terminal voltage are reduced substantially, which contributes to improving power factor and field-weakening property. When operating below base speed, higher voltage margins are obtained, thus the proposed PMVM exhibits a higher power factor and wider constant torque region. With speed over base speed, the field-weakening control strategy is adopted, allowing the proposed PMVM to employ a higher q-axis current to generate torque. As a consequence, the output capability and power factor under high-speed field-weakening region are improved. In particular, the maximum achievable output power is improved by 19%, and the constant power speed range (CPSR) ratio is improved from 2 to almost 10.

The three-level neutral-point-clamped (NPC) converter is a promising topology for motor control. However, its large number of voltage vectors imposes a heavy computational burden on the conventional finite-control-set model predictive control (MPC). Furthermore, variable frequency is another barrier limiting the development of MPC, i.e., challenging to evaluate the power loss and EMI suppression. To address these concerns, this paper proposes a low complexity MPC method for three-level converters. While maintaining lower current distortion and fast dynamic response, the novel method has the desired characteristics of fixed switching frequency and no need for cumbersome weighting factor’ tuning. First, the vector space of the three-level converter is divided into 6 small hexagonal sectors. Second, the sector judgment and execution time calculation are greatly simplified by using the similar two-level action law in each sector. More importantly, multiple-voltage-vector is adopted during each control period and the fixed switching frequency is realized through the proposed allocating action sequence. The validity of the proposed algorithms is evaluated by simulation and experiment results in contrast with other state-of-the-art MPC.

High-performance position sensorless control requires accurate motor phase voltages in the entire speed range, especially in zero-speed and low-speed regions. Inverter nonlinearity has been becoming a main barrier restricting the development of PMSM sensorless, it is essential to eliminate the effect of inverter nonlinearity on the overall control scheme. This paper proposed a universal compensator by combing a proportional integral resonant controller and Luenberger observer. Compared with other compensators, the proposed compensator can be directly utilized in PMSM control scheme under different PMSM speeds. In addition, the theoretical analysis and parameter tuning guideline are firstly elaborated. In order to verify the effectiveness and correctness of the proposed controller, relevant experiments of the proposed approach are carried out in this paper.

Permanent magnet vernier machines (PMVMs) are recognized as the most promising candidates for high-torque direct-drive applications. However, their market penetration is hindered by the low power factor. This paper aims to address the low-power-factor challenge, by employing the concept of low-coupling winding. As compared with two conventional PMVMs, the proposed PMVM with low-coupling winding exhibits a substantially improved power factor. To objectively evaluate the potential of the proposed PMVM, a comprehensive comparison between the proposed PMVM and the conventional permanent magnet synchronous machine (PMSM) is conducted. The no-load back-EMF, output torque, power factor, core losses, and efficiency are compared under various operating conditions, encompassing the entire torque-speed range. The strengths and weaknesses of the PMVM are analyzed, and the most promising application scenarios are suggested. Finally, a prototype of the proposed PMVM is fabricated to validate the analysis and comparison results.

This paper investigates the two-slot pitch winding vernier machine by stator shifting technique (SST). It shows that the conventional two-slot pitch winding vernier machine can be generated by SST with a special stator shift angle. This paper contributes to exploring other shift angles and their influences on machine performances. Analysis results indicate that different shift angles have a great effect on the armature winding magnetomotive force (MMF) harmonic contents and the flux modulation effect. Consequently, the phase inductance, power factor, core losses, and torque capability will be affected. A single-layer 24-slot/10-pole vernier machine is investigated for verification, and the results show that with an appropriate shift angle, the power factor is improved from 0.6 to 0.7, the iron losses are reduced by 24.5%, and the efficiency is improved by 0.7%, with a slight torque drop of 2.9%.

This paper focuses on deadbeat predictive current control (DPCC) for a surface permanent-magnet synchronous motor (SPMSM). One of the main drawbacks that are limiting the widespread application of this control is the disturbance caused by model parameter mismatch. In order to address this problem, a novel DPCC with parameter mismatch compensation for SPMSM is proposed in this paper. The contribution of this work can be divided into three parts. First, the real inductance can be acquired from the d-axis voltage equation online based on the previous instant voltage and current information. Second, with the acquisition of the d-axis inductance, a novel voltage equation with one step delay compensation is proposed to reject the disturbance caused by rotor flux linkage and inductance at the same time. Third, the initial resistance parameter effect on the proposed DPCC is analyzed theoretically. To verify the effectiveness of the proposed DPCC, the conventional DPCC and proposed DPCC are compared. The results demonstrate that the proposed DPCC can effectively reject the parameter mismatch disturbances in both simulation and experiment.