Bridgeless power factor correction (PFC) converter is popular for reducing the conduction losses of semiconductors. In this paper, a novel bridgeless Cuk PFC converter is proposed. Compared to the conventional Cuk PFC converter, the number of conducting semiconductors in the proposed bridgeless Cuk PFC converter is reduced, contributing to lower conduction losses. Moreover, the conduction losses in proposed converter are further improved compared with the pseudo totem-pole bridgeless Cuk PFC converter. Meanwhile, the total number of component in the proposed converter is less than other bridgeless Cuk PFC counterparts, especially for the big-volume magnetic component and electrolytic capacitor. In addition, all power switches in the proposed converter are common-ground and can be driven by one control signal, availing simple drivers. The theoretical analysis of the proposed converter is presented in discontinuous conduction mode (DCM) with the merits of nature current sharping ability, zero-current switching in semiconductors and easy control. Finally, the simulation and an 100W lab-prototype are built to validate the feasibility of the proposed bridgeless Cuk PFC converter.

The use of interior permanent-magnet synchronous machines (IPMSMs) is prevalent in automotive and vehicle traction applications due to their high efficiency over a wide speed range. Given the high-power-density requirements of automotive IPMSMs, it is imperative to consider the effect of nonlinearities, such as saturation and cross-coupling, on the motor model. The aforementioned nonlinearities render conventional linear motor models incapable of accurately describing the operating characteristics of the IPMSM, including the maximum torque per ampere (MTPA) trajectory, the flux-weakening (FW) trajectory, and the maximum torque per volt (MTPV) trajectory. With respect to the linear motor model, the nonlinear flux-linkage model is gradually receiving attention from researchers. This modeling method represents the nonlinear behavior of the motor through the direct establishment of a bidirectional mapping relationship between flux-linkage and current. It is capable of naturally incorporating the effects of magnetic saturation and cross-coupling factors. However, the analysis of the current trajectory optimal criteria based on this model has not yet been reported. In this paper, the optimal criteria for the MTPA and MTPV current trajectories are analyzed based on the nonlinear flux-linkage model of IPMSMs. Firstly, the nonlinear flux-linkage model of the tested IPMSM is established by the experimental calibration method. The mathematical analytical expressions of the MTPA and MTPV optimal criteria are then analyzed by constructing and solving optimal problems with different objectives. Finally, the current command table applicable to actual motor control is constructed by calculating the current command for different operating conditions according to the optimal criteria proposed in this paper. The validity and feasibility of the optimal criteria proposed in this paper are verified through experimental tests on different operating conditions.

Torque density is a crucial performance metric for flux-switching permanent magnet (FSPM) machines. However, the emergence of flux barriers tends to impede the magnetic field modulation effect, especially in machines with high pole ratios, ultimately impacting overall performance. To solve this issue, this paper proposed a consequent-pole FSPM machine with a flux-concentrated magnet design. The proposed machine adopts a 12-slot/13-pole configuration with a pole ratio of 13. To optimize the magnetic field concentration, the design integrates shortened clockwise tangentially magnetized PMs under an “h” core, positions radially magnetized PMs at the core's shoulders, and inserts counterclockwise tangential PMs into the slot openings. This arrangement effectively addresses the magnetic barrier issue, enhancing the magnetic field compactness within the machine. The operating principle of the proposed FSPM machine is analyzed using analytical computations and finite element analysis (FEA). The structural parameters are optimized for maximum average torque and efficiency. The proposed machine offers a 14.96% higher average torque and 2.1% higher efficiency than the existing FSPM machine with flux bridges at the same stator copper loss. A 640 W-rated prototype of the proposed machine was fabricated and tested, validating the simulation results and design accuracy through experiments.

Thrust ripple and density greatly impact the performance of the linear machine and other linear actuators, causing positioning control precision, dynamic performance, and efficiency issues. Generalized pole-pair combinations are difficult to satisfy both the thrust and ripple for double salient reluctance linear machines. In this paper, a DC-Biased vernier reluctance linear machine (DCB-VRLM) is proposed to solve the abovementioned issues. The key to the proposed design is to reduce the ripple and enhance the thrust density with non-uniform teeth by utilizing and optimizing the modulated flux in the air gap. To effectively verify the proposed design, the DCB-VRLMs with different winding pole pairs and secondary poles are compared. The 12-slot/10-pole combination is chosen to adopt a non-uniform air gap structure. Moreover, the energy distribution of AC/DC winding is studied and optimized to further enhance the performance of the proposed DCB-VRLM. The results indicate that the DCB-VRLM with the non-uniform air gap has a lower thrust ripple, better overload capability, and higher thrust density, which confirms its superiority in long-stroke linear rail transit and vertical elevator applications.

This paper proposes a complex vector discrete current controller based on the flux-linkage data to solve the current loop oscillation problem of high power-density synchronous machines. An offline flux-linkage table measurement method considering cross saturation is introduced, and the data are used to deduce the symmetrical complex vector model. The influence of latch and delay of inverters on the line voltage of machines at high speed is analyzed and compensated during the controller design process. The proposed controller, which only needs to tune one parameter, can deal with the inductance mismatch issues caused by iron core saturation. The controller can be adopted in the current loop of saturated salient or nonsalient synchronous machines. Simulations and experiments have verified the effectiveness of the proposed method.