This paper introduces a novel multi-frequency cascade disturbance observer (MF-CDOB) designed for permanent magnet synchronous motor (PMSM) drives. Unlike conventional disturbance observer (DOB) techniques, the proposed MF-CDOB employs a cascaded arrangement of multiple DOBs. This unique structure effectively decouples the frequency responses, enabling independent tuning for the rejection of both aperiodic and harmonic disturbances. Developed in the discrete-time domain, the method offers enhanced real-time disturbance rejection without compromising transient performance. Preliminary experimental results validate that the MF-CDOB significantly reduces harmonic content and improves current regulation compared to traditional control schemes.

A novel dual-rotor transverse flux permanent magnet machine is proposed in this paper. The key to this proposed machine is to add the dual-rotor structure based on the conventional transverse flux permanent magnet machine. The main contribution of this design is to generate a high frequency air-gap flux field with two rotors that rotate at low contra-rotating speeds through flux modulation effect, which increase the speed of the whole system. Moreover, the stator structure is modified based on C-type stator in conventional transverse flux permanent magnet machine. The optimized stator is beneficial to reduce the flux leakage and the machining difficulty. In this paper, flux field modulation principle in dual-rotor structure is first analyzed. And then, The C-type stator is designed and further optimized. Finally, the overall structural design is selected and make the comparison with the conventional transverse flux permanent magnet machine through finite element method.

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.

a novel dual-rotor permanent magnet multiport machine with C-type stator is proposed in this paper. The key point of this proposed machine is using the C-type stator to separate the magnetic and electric load. It is contributed to decrease the air-gap length to improve the torque density. For the conventional multiport machine, the main flux path flows across six-layer air-gaps because of the dual-rotor, dual stator structures. Compared with the conventional multiport machine, the proposed machine with C-type stator just across three-layer air-gaps. Moreover, the outer and inner rotor of the proposed machine rotates based on flux field modulation principle at the contra-rotating speed to generate the high frequency air-gap flux field. In this paper, the overall structure of this machine is first introduced. Second, the flux field modulation principle in dual-rotor structure and the flux circuit in C-type stator is analyzed. Finally, the prototype of the proposed machine is selected and compares with the conventional dual-rotor permanent magnet multiport machine through finite element analysis method.

Reluctance machines with DC field coil in the stator is a competitive candidate for electric vehicle propulsion due to the elimination of rare-earth permanent magnets (PM), robust structures and controllable excitation. However, their torque density cannot be compared with PM machines. Introducing rare-earth PMs into reluctance machines can be an effective way to boost torque density, but the costs will greatly increase as well. To solve this problem, this paper proposes a hybrid reluctance motor using assistive ferrite magnets in stator slots. The introduced ferrite magnets operate based on the flux modulation effect for torque density improvement. It is revealed by finite element analysis, with ferrite magnets in stator slots, machine torque density and efficiency can be improved by 20.2% and 5.1%, respectively.

This paper proposes three novel dual-stator flux-modulated permanent magnet (DSFMPM) machine concepts, which are particularly suitable for direct-drive applications with the virtue of their high torque density and low operation speed. The dual-stator configuration can help improve the use of inner cavity space, and achieve higher torque density comparing with the single-stator counterparts. Moreover, flux modulation is artfully employed to produce the gear effect, which can further benefit for the torque improvement. According to the PM location, the proposed DSFMPM machines are referred as (i) Stator-PM machine, (ii) Stator-rotor-PM machine, and (iii) Rotor-PM machine. Finite element method coupled with genetic algorithm, namely FEM-GA coupled method, is used to optimal design the proposed DSFMPM machines. Their electromagnetic performances are investigated in detail and quantitatively compared. The results show that the dual-stator topology can well improve the torque capability. Among all the proposed DSFMPM machines, the stator-PM one owns the lowest torque density because it has more short-circuit leakage flux.