This letter proposes winding switching for the high-performance of permanent-magnet vernier machines (PMVMs) in wide speed range operation. The machine is operated in two modes: cumulative and differential. Before winding switching (cumulative mode), the machine is operated like a conventional three-phase PMVM. The machine provides high torque density and high efficiency in this mode. After winding switching (differential mode), the back EMF and inductance of the machine are decreased significantly, which enable wide speed range operation and the attainment of high power factor in high-speed operation.

This paper proposes to turn to switch along with winding switching for high-efficiency of permanent magnet vernier machines (PMVM) during wide speed range operation for electric vehicles application. For winding switching, the three-phase winding of the machine is divided into two sets of windings, namely, winding set A, B, C and winding set X, Y, Z. For turn switching, the number of turns for one set of winding is changed. With the different number of turns for winding set X, Y, Z, the efficiency of the machine can be significantly improved. Initially, the basic electromagnetic characteristics, such as the flux linkage, back electromotive force (EMF), torque, and phase voltages of the machine are investigated using winding switching and turn switching. Then, the output power, torque-speed curve, core losses, efficiency, and power factor of the machine are analyzed in detail using a different number of turns. In addition, the transient effects of winding switching and turn switching have been analyzed. Finally, a control strategy is proposed which combines turn switching and winding switching to ensure high-efficiency of PMVMs during wide speed range operation. A PMVM is designed and driven in accordance with the proposed control strategy (PCS) to show the characteristics of PCS. The PMVM driven with PCS is compared to a recently presented PMVM. The recently presented PMVM is driven by a different control strategy and is analyzed with two different kinds of steel laminations that are general steel (50TW470) and special steel (20JHF1300). INDEX TERMS High efficiency, permanent magnet vernier machine, turn switching, wide speed range, winding switching.

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A high gear ratio flux switching permanent magnet machine (HFSPM) was proposed to improve the torque performance in flux switching permanent magnet machine (FSPM). Conventional FSPMs address flux bypass issue when designed with a high gear ratio. The HFSPM adopts a dual rotor structure to overcome this flux bypass issue. First, the cause and effect of flux bypass issue was discussed using a magnetic equivalent circuit (MEC). Further, the process of overcoming the flux bypass issue using dual rotor structure was discussed. An alternative HFSPM, consequent pole HFSPM (CP-HFSPM), was proposed to enhance torque performance. The CP-HFSPM was optimized for high torque performance and proper power factor.

This paper proposes a wound field pole changing vernier machine with fractional slot concentrated winding for electric vehicles application. The main aim of the paper is to utilize the advantages of a vernier machine and a wound field synchronous machine in a single topology using a fractional slot concentrated armature winding. The proposed machine operates in a vernier mode at low speeds and a wound-field synchronous mode at high speeds to utilize the merits of both a vernier machine and a wound-field synchronous machine. The topology, operating principle and pole-changing method of the proposed machine are explained initially. Then, finite element analysis (FEA) is utilized to study the electromagnetic characteristics such as back EMF, torque, wide speed range operation and efficiency of the proposed topology in two modes. Further, a prototype of the machine is manufactured and the FEA results are validated through experiments. The FEA and experiment results show that the proposed machine is a promising candidate for electric vehicles application. INDEX TERMS Electric vehicles, pole changing, wound field synchronous machine, variable speed, vernier machine.

Abstract:In this paper, a permanent magnet (PM)-less, brushless, wound-rotor vernier machine (BL-WRVM) is proposed for variable speed applications such as electric vehicles and washing machines. The wound rotor is excited through an already existing brushless topology, which requires a dual inverter configuration to generate an additional subharmonic component in the stator magnetomotive force (MMF). Different from permanent magnet vernier machines (PMVMs), the proposed BL-WRVM provides easy regulation of the rotor flux for variable speed operation. A 24-slot, 4-pole stator, and 44-pole outer rotor were designed, and 2D finite element analysis (FEA) was carried out to determine the performance of the proposed machine. To improve the performance of the proposed machine, optimization of the rotor and stator winding turns was done. The optimized model was further analyzed for wide-speed operation, and its performance was then compared with that of an equivalent permanent magnet vernier machine (PMVM). The proposed machine has the advantage of low cost due to its PM-less structure and is suitable for variable speed applications.

This paper proposes a rotating electronic billboard (REB) to save the cost of space required for its installation and a modular linear induction machine (M-LIM) to rotate the proposed REB. REBs are generally installed in public places such as subways and airports to display the advertisements. The proposed REB can be installed around a pillar since it is hollow inside, hence, no additional space is required which limits the cost of the space required for REBs. The proposed M-LIM for rotating the proposed REB has a short straight primary and a ring-shaped secondary. The secondary is installed on top of the light emitting diode (LED) display bars such that when secondary rotates, LED bars rotate along with it. To confirm the suitability of the M-LIM in proposed REB, an M-LIM is designed, and the initial results are examined using three-dimensional finite element analysis (3-D FEA) to consider the 3-D effects in the proposed design. A prototype of the proposed M-LIM along with the proposed REB is manufactured and their collective performance is evaluated experimentally. The results show good agreement with the simulation.