Eccentricity fault in electrical motor causes increased noise and vibration, and degradation of motor characteristics. Thus, early detection of the eccentricity fault is required. Motor current signal analysis, a common fault detection method, may fail to detect eccentricity faults, depending on the type of eccentricity. This article proposes an eccentricity fault detection method using a new planar search coil (PSC). The model of PSC and the contribution of eccentricity to PSC are presented. PSC is a new type of search coil that generates a voltage signal from magnetic flux. The output signal of PSC is changed by the inductance deviation, a result of the rotor eccentricity. Finally, the experimental verification of fault detection using PSC is shown. The eccentricity fault detection method using PSC is proven to diagnose both dynamic eccentricity and static eccentricity faults.

Conventional position sensors for permanent magnet synchronous motor, such as optical encoder, resolver, or hall sensor, can get fault by the stress. The fault of the motor position sensor may cause serious accidents. Thus, to prevent damages by the position sensor failure, adding a redundancy sensor such as wound search coil is recommendable. In this paper, a new planar search coil design that can be used as a position sensor for permanent magnet synchronous motor is proposed. This new design is a planar coil based on a flexible-printed circuit board that converts airgap flux to a back-electromotive force signal. Unlike the wound search coil design, the proposed design is advantageous for manufacturing and slot-space preservation. Also, this new design is distant from the motor main winding. As a result, the exposure of the electrical and thermal stresses to the sensing coil can be decreased. This research shows the mathematical model for the design of the new planar-shaped airgap flux search coil design. In addition, the position estimation algorithm based on the new search coil design is shown. Finally, the position estimation using the new search coil design is presented.

This paper proposes a method of eliminating common-mode voltage (CMV) and shaft voltage in dual three-phase motors using the carrier phase shift of space vector pulse width modulation (SVPWM). SVPWM for the dual three-phase motor is simply implemented using two traditional three-phase SVPWM structures. The representative work of the study is to eliminate the shaft voltage by applying the carrier phase shift method due to the cancellation of CMV. It was verified that the proposed method could reduce the shaft voltage with a simple technique, rather than applying a complex algorithm to reduce it. Also, the motor current and torque behaviors are analyzed to confirm that the proposed method does not affect the motor characteristics. The proposed method has been analyzed based on an equivalent circuit model and it has been verified through the experiment that the shaft voltage is simply eliminated by applying the proposed method.

As the era of electrification advances, the demand for increased power density and high efficiency in electric motors, such as those in electric vehicles and E-mobility, has been rising. This has led to an increase in the application of higher DC voltages and the use of high-performance switching devices. In particular, with the design of high-performance interior permanent magnet synchronous motors (IPMSM), which are widely used as traction motors in many vehicles, there is a growing need to address motor faults. IPMSMs are driven by PWM inverters for traction motors, and during this process, a common mode voltage (CMV) occurs, where the sum of the three-phase voltages of the winding does not become zero. This CMV component causes circulating currents through the parasitic capacitances within the motor from the windings, generating current paths. As a result, voltage is induced on the motor shaft, which applies voltage to the bearings, leading to bearing damage. Such bearing faults can cause mechanical and electrical defects in the motor and even lead to vehicle breakdowns. Therefore, since bearing faults can threaten the driver’s life, this paper proposes a new shield structure designed to reduce shaft voltage and prevent bearing faults.

This paper proposes a special design of a dual stator radial type permanent magnet vernier machine (PMVM) having a yokeless rotor to improve the torque density. The PMVM model is designed with winding only in the outer stator, while the inner stator is kept auxiliary without winding. The proposed model reduced the overall volume of the machine, which in turn improved the torque density of the machine. The proposed configuration makes the design free from thermal and manufacturing issues due to the absence of inner stator winding. The detailed specifications and analysis results of the proposed model, such as torque, back EMF, inductance, and other features, are presented in this paper. The model is analyzed and compared with the dual stator radial type PMVM having a yokeless rotor and dual stator winding using the 2D-Finite Element Method (FEM) as well as 3D Co-simulation with Ansys Mechanical.

This paper presents a novel topology of dual airgap radial flux permanent magnet vernier machine (PMVM) in order to obtain a higher torque per magnet volume and similar average torque compared to a conventional PMVM machine. The proposed machine contains two stators and a sandwiched yokeless rotor. The yokeless rotor helps to reduce the magnet volume by providing an effective flux linkage in the stator windings. This effective flux linkage improved the average torque of the proposed machine. The competitiveness of the proposed vernier machine was validated using 2D finite element analysis under the same machine volume as that of conventional vernier machine. Moreover, cogging torque, torque ripples, torque density, losses, and efficiency performances also favored the proposed topology.