Fast online detection of inter-turn short-circuit faults for permanent magnet synchronous machines (PMSMs) is a challenging task. Previous attempts based on phase currents or back EMF monitoring lack the capability to accurately locate the inter-turn short-circuit faults in stator windings. This work proposed a new approach to online inter-turn short-circuit fault detection for PMSMs by means of sensing the external stray magnetic field outside the motor stator yoke. The stray magnetic field provides the information about the phase currents as well as the status of stator windings; thus, the location of inter-turn short-circuit fault can be detected accordingly. In this work, the inter-turn short-circuit model and the stray magnetic flux model for PMSMs were theoretically analyzed. Both FEM simulations and experiments have been presented to validate the effectiveness of the proposed approach. A sensor array composed of 24 sensitive tunneling magnetoresistive (TMR) sensor units was employed to measure the stray magnetic field distribution outside the PMSM stator yoke. The experimental results show that both the location and severity of the inter-turn short-circuit fault in PMSMs were effectively detected using the proposed approach.

This article proposes and implements a brand-new wireless power and drive transfer (WPDT) system using wireless switches. A wireless piping network is conceived especially for pipeline transportations and in-pipe robots desiring wireless motor drive. Also, a multifrequency resonant network is newly explored to generate the variable-frequency-modulated magnetic fields where the wireless switches can extract the drive information directly. Differing from single-frequency T-circuits, this multifrequency network can offer different resonant frequencies which are not only coupling-independent but also large-scale load-independent. Importantly, it can realize both the power self-equalization and zero-phase-angle operation in transmitter and receiver circuits. To conduct the conceived WPDT, the magnetic resonant modulation is used to control the wireless switches automatically at the receiver side, thus flexibly enabling the bidirectional motions of dc motor and the variable-frequency speed control of ac induction motor. The experimental system efficiency can reach 83.5% based on a 200-W prototype at a 130-mm distance. Both theoretical analysis and hardware experimentation are given to verify the feasibility of proposed WPDT system for wireless piping networks.

In this paper, a wireless shaded-pole induction motor (SPIM) is proposed and implemented, which artfully integrates wireless power transfer (WPT) into a single-phase SPIM to achieve the first wireless AC motor. Prominently, there is no controller at the SPIM side, as the controlling process is fully conducted at the transmitter side. Meanwhile, there is no need to specially design the motor, as all existing SPIMs can readily be used. The key is to propose a self-driving circuit in the receiver, which can provide variable-voltage variable-frequency control of the SPIM. As a result, the proposed wireless SPIM takes the definite advantages of electrocution-free and totally sealable. A 110-W prototype has been built for experimental verification. It can offer wireless speed control from 486 rpm to 1330 rpm with the transfer distance of 30 mm and the transmission efficiency of 86.2%.

In this paper, a novel double-rotor flux-switching permanent-magnet (DR-FSPM) motor is proposed for electric vehicles with the capability of magnetic differential (MagD). The key is to introduce a new set of winding which magnetically couples with the two rotors of the DR-FSPM motor in such a way that the magnetic coupling winding field can interact with the PM fields in the two rotors. Hence, the differential torque can be generated between wheels to achieve accurate cornering during vehicle steering. Consequently, the proposed system can offer higher efficiency and compactness than the conventional mechanical differential system, while provide higher reliability and safer operation than the electronic differential system. The operation principle and performances of the proposed DR-FSPM motor are thoroughly analyzed by finite element analysis while the proposed MagD system is also evaluated with system simulation. Finally, the motor prototype is built while the prototype and MagD system are tested for experimental verification.

In this paper, a comparative study of permanent-magnet vernier (PMV) motors and the interior permanent-magnet (IPM) motor for hybrid electric vehicles (HEVs) is presented. Four different topologies of PMV motors, including the conventional PMV motors and the developed U-shape PMV (U-PMV) motors with full-pitch (FP) and short-pitch (SP) windings, are comprehensively investigated and compared. The results show that higher torque and PM utilization can be achieved in the developed U-PMV motors due to the improved flux modulation effect. In addition, SP windings can facilitate PMV motors to achieve higher output torque/power, efficiency, and PM utilization when a high power factor is required. The improvement of the flux modulation effect in the developed U-PMV motors is explained using the simplified magnetic circuit, while the advantages of SP winding over FP winding at a high power factor level are illustrated using winding function theory. To evaluate the performances and potential of PMV motors for HEVs, both the conventional PMV and the developed U-PMV motors are optimized and compared with the IPM motor under fair conditions. The results show that PMV motors offer higher torque density, power density, and lower torque ripples, compared to the IPM motor. However, more PM consumption and higher cost of PMV motors are the disadvantages of PMV motors for automotive applications where cost constraints are sensitive.

In this paper, a quantitative comparison of five new dual-permanent magnet (PM) linear motors with fault-tolerant teeth is presented, which are promising for application to the ropeless elevator propulsion system. The proposed linear motors have PMs on both the mover and stator, leading to a new class of dual-PM linear motors. In addition, they can offer the advantages of high reliability and fault-tolerant capability, owing to the presence of fault-tolerant tooth mover structure. By using JMAG based finite-element analysis, the electromagnetic performances of five proposed machines are analyzed and quantitatively compared. The comparison results show that the double-mover tooth-PM linear machine is most preferable for application to the ropeless elevator propulsion system because of its high force density, low force ripple and small attraction force. Finally, both the analysis results and experimental verification are given to verify the investigation.