This research investigates the detection of the detailed static air-gap eccentricity position (SAGE) at both ends of non-salient pole synchronous generators (SG). Differently from the previous studies, the detection method proposed does not necessitate the installation of invasive sensors inside the generator and instead it is based on two groups of symmetrically distributed search coils placed at both end-sides outside the generator. The root mean square (RMS) value comparison in electromotive forces (EMFs) of the search coils is then employed to assess the exact SAGE position of each end-side. Numerical 3D finite element calculation together with an experimental campaign on a two-pole 3000rpm CS-5 prototype synchronous generator validates the effectiveness of the proposed method. It is shown that the maximum assessment error by using four external search coils at each end is 15.1%, while by setting more coils the error can be significantly reduced. Since this proposed method has no need to install invasive search coils inside the generator, it is more convenient for field testing and helps improve the cost-performance of online SAGE condition monitoring.

Radial force is the main cause of electromagnetic vibration and noise in motors. In this study, the vibration and noise characteristics of a permanent magnet synchronous motor (PMSM) with consideration of rotor‐step skewing are investigated. Firstly, the analytical model of considering rotor‐step skewing is deduced based on the Maxwell stress tensor method. The influence of rotor‐step skewing on of the PMSM is then analysed and summarised. Taking a 65 kW PMSM commonly used in electric vehicles as an example, combined with electromagnetic finite element analysis, is then evaluated. Secondly, an electromagnetic vibration and noise simulation analysis is conducted based on a multi‐physical field joint simulation platform, from which the influence of rotor‐step skewing on the vibration and noise is then summarised. Finally, a noise experiment is then carried out. The results obtained from the multi‐physical analysis and the tests conducted are presented to validate the precision of the simulation models, and the accuracy of the analytical model of .

An active magnetic bearing (AMB) is a kind of high-performance bearing that uses controllable electromagnetic force to levitate the rotor. Its control performance directly affects the operation characteristics of high-speed motors and other electromechanical products. The magnetic bearing control model is nonlinear and difficult to control. Sliding mode control algorithm can be used in the magnetic bearing control system, but the traditional sliding mode control has the problem of high-frequency chattering, which affects the operation stability of magnetic bearings. Based on the second-order sliding mode control algorithm, a new second-order sliding mode controller for active magnetic bearing control was designed, and the stability of the designed sliding mode control law was proven by Lyapunov criterion. On the basis of the established active magnetic bearing control model, the numerical analysis of the designed controller was carried out, and the control effect was compared with that obtained by the exponential reaching law for the sliding mode control algorithm. The experimental results show that the designed sliding mode controller has better dynamic performance and stability than the exponential reaching law for the sliding mode controller.

The high-speed permanent-magnet synchronous machine (HSPMSM) has stricter mechanical restrictions and more intense interactions between multiphysical fields due to high-speed and high-power density characteristics. This article focuses on the thermal effect on mechanical strength and stiffness. As the change of material properties with temperature and the thermal stress caused by thermal expansion properties, this article presents the relationship of the stress and critical speed with two thermal effects obtained by analytical equations and verified by finite-element analysis. The results show that thermal effects could reduce the safety factors of the stress and critical speed, thus increasing the possibility of rotor damage and resonance. To achieve more accurate mechanical, a reasonable machine design is proposed, focusing on the influence of actual uneven thermal distribution. Comparing with a traditional design approach, the new one is more applicable for the HSPMSM design, which considers the assembly method and the operation condition, especially the thermal effects. The fluid-thermal-stress-mode coupling calculation is realized. The experiment has been implemented to verify the validity of this design process. The studies of the thermal effects on mechanical characteristics offer a new idea for designing and debugging practical machines.

The in-wheel motor has received more attention owing to its simple structure, high transmission efficiency, flexible control, and easy integration design. It is difficult to achieve high performance with conventional motors due to their dimensions and structure. This paper presents a new dual-stator and dual-field-excitation permanent-magnet in-wheel motor (DDPMIM) that is based on the structure of the conventional in-wheel motor and the structure of both the radial and axial magnetic field motor. The finite element analysis (FEA) model of the DDPMIM is established and compared with that of the conventional in-wheel motor. The results show that the DDPMIM achieves a higher output torque at low speeds and that the flux-weakening control strategy is not needed in the full speed range.

This article proposes a new rotor interturn short circuit (RISC) fault analysis model for the electromechanical property study in synchronous generators. The specific novelty of this model lies in two aspects: First, It considers that most generators exist static air-gap eccentricity (SAGE), so it analyzes the RISC fault under normal and SAGE, making the model more versatile, and second, it takes into account not only the short circuit degree, but also the short circuit position, consequently it is more universal. By feeding the number of short circuit turns (denotes the short circuit degree), the angle between the two slots, where the short circuit takes place (denotes the short circuit position) and the detailed parameters of the generator into the model, the developing tendency of the key magnetic flux density (MFD)-based parameters can be conveniently predicted. The advantages of the proposed model primarily lie in the universality and the calculation speed. It can quickly evaluate the generator operating conditions. The phase current and the electromagnetic torque are selected in this article as the representatives of the electrical parameter and the mechanical parameter, respectively. Two-dimensional finite element analysis and experimental studies validate the proposed model.