Ping Zheng

Dual three-phase permanent magnet synchronous machines (DT-PMSMs) have great application potential in aerospace actuation systems due to their high fault-tolerant capabilities. However, stator winding open-circuit faults (OCFs) represent a critical threat to the operational reliability of machines. Conventional diagnostic methods often rely on complex machine models, and their diagnostic results are frequently affected by torque and speed fluctuations, limiting their effectiveness in dynamic scenarios. In contrast, diagnostic approaches utilizing harmonic subspace current features allow for the direct observation of electromagnetic asymmetries and offer high potential for rapid identification. This paper proposes a fast and accurate OCF diagnostic method for both single-phase and two-phase faults based on optimized harmonic subspace current features. By establishing the intrinsic mapping relationship between the z1-z2 harmonic subspace and the fundamental current plane, fault features with low sensitivity to load variations are constructed. Specifically, the incorporation of a bias term δ effectively resolves the numerical singularity inherent in 180° spatially apart OCFs, enabling the identification of all fault types. Furthermore, the diagnostic features are refined via adaptive filtering and partial-cycle averaging to suppress impulsive spikes and minimize detection latency. Experimental results at 2000 r/min demonstrate that the proposed method precisely identifies and localizes faults within 1/10 to 1/5 of an electrical cycle, providing an accurate and efficient solution for aerospace actuators.

improve the performance of multi-phase PMSMs under open-circuit (OC) faults, OC fault-tolerant control (FTC) methods are extensively investigated under high carrier ratio conditions. However, due to the complexity of the fault-tolerant (FT) mathematical model, cross-coupling effects in signal flow between d- and q-axes and the digital delay from current sampling to voltage output in digital controller, the FTC performance may degrade under low carrier ratio (LCR) conditions. To address these issues, this paper proposes a novel FTC method for single phase open-circuit faults in a symmetrical six-phase PMSM with fractional-slot concentrated windings under LCR conditions. In this method, considering the distinctive inductance matrix of the investigated machine, an FT coordinate transformation method is developed. The transformation method simplifies the mathematical model of FT currents, back electromotive force (EMF), and inductance matrix in synchronous space. Further, a current control method based on discrete second-order rotational-decoupling control (DSRDC) is investigated. Through this control method, the cross-couplings in both d-q axis and d1-q1 axis are decoupled, and the FT current loop performance can be configured while sufficiently considering the digital delay. The proposed FTC method enables the FT operation on the investigated machine under LCR conditions with good stability and dynamic performance. Moreover, a smooth transformation method from OC fault to FT condition is investigated. The effectiveness is verified through experiments.

This paper proposes a dual internal model (DIM) decoupling control method with delay compensation, in which the internal model principle is applied to both the voltage loop and the current loop to solve the high order and strong coupling problems of the permanent magnet synchronous motor (PMSM) system fed by the current source inverter (CSI). By means of deriving the complex-vector model of the CSI-fed PMSM system, the influence of cross-coupling caused by coordinate transformation is analyzed and the decoupling performance of the DIM decoupling control method is quantitatively evaluated. To overcome the influence of control delay and angle coupling, the model of the DIM decoupling control method in the discrete domain is derived. The codesign method of controller parameters and the delay compensation coefficient is introduced and compared with the traditional decoupling method. Finally, the experimental results show that the proposed decoupling method can improve the control performance in both dynamic and steady states.

This paper proposes a robust short-circuit fault diagnosis method based on dual-scale average current errors for the permanent magnet synchronous motor (PMSM) drive fed by the current source inverter (CSI). The method only employs the already exist motor currents and does not need additional sensors and circuits, which is simple and easy to implement. The current errors between the average values of the reference currents and that of the feedback currents in one cycle are calculated, and the ratios of the errors to the average absolute values of the reference currents are used as the diagnostic variables. In addition, two amplitude thresholds are set to determine the fault type by comparing the diagnostic variables with the amplitude thresholds. Then, the faulty switch is located according to the signs of the diagnostic variables. In order to avoid misdiagnosis in the transient processes, a time threshold as the second scale is set to enhance the robustness of the diagnostic algorithm. Finally, an experimental platform is built to verify the effectiveness and the robustness of the proposed diagnosis method.

Due to the inherent fault‐tolerant capability, the multi‐phase permanent‐magnet synchronous machine (PMSM) is suitable for applications with high reliability requirements. Modular‐stator design is beneficial for fault isolation and will further enhance the reliability of multi‐phase PMSM. Fractional‐slot concentrated winding (FSCW) is widely applied in multi‐phase PMSM. However, it will cause higher space harmonics and losses than those of the conventional distributed winding. The influence of modular‐stator design on the space harmonic characteristics of six‐phase PMSM is investigated in this paper. Five modular‐stator six‐phase PMSM schemes with different magnetic barrier locations are developed. Based on the analysis of the equivalent magnetic circuit, the variation of magnetic field distribution is studied, and the suppression ability of the non‐working space harmonics of the armature magnetic field is demonstrated. By analysing the alternating frequency of flux density in different positions, the correlation between loss types and magnetic field harmonics is investigated. An optimal scheme of low‐space‐harmonic modular‐stator six‐phase PMSM (LSHMS‐SPPMSM) is designed. Compared with the PMSM with a non‐modular stator, its core loss and permanent‐magnet (PM) eddy current loss of the six‐phase modular‐stator PMSM are significantly reduced and the electromagnetic torque is increased. Finally, a prototype is built, and experiments are carried out to verify the analysis results.

This paper proposes a novel backstepping-adaptive resonant controller (BARC) specifically designed for low-speed permanent-magnet synchronous machines (PMSMs) to mitigate speed fluctuations caused by both periodic and aperiodic disturbances. First, the conventional adaptive resonant controller (ARC) is analyzed for its capability to eliminate periodic disturbances with uncertain frequencies. Given the nonlinear characteristics of the friction torque during low-speed reciprocating operation, a backstepping control method based on the LuGre friction model is employed to further suppress aperiodic disturbances. This method utilizes dual nonlinear observers and adaptive laws to estimate the nonlinear friction and load torque. Simultaneously, these estimated aperiodic disturbances are adapted to the adaptive resonant controller to enhance its robustness. Furthermore, the convergence and stability of the proposed strategy are analyzed by Lyapunov theory, and the influence of parameter variation is evaluated. The effectiveness of the proposed strategy is experimentally validated on a low-speed PMSM drive platform. Experimental results show that the speed fluctuation is reduced by 87% compared to PI controller and both dynamic response and steady accuracy are improved over the conventional ARC.

The dual-rotor Permanent-magnet motor, characterized by its efficient utilization of internal space, offers significant potential for improving torque density. This paper presents a comparative analysis of series and parallel magnetic circuit topologies of dual-rotor motors under considering practical processing. This paper establishes equivalent magnetic circuit models for qualitative analysis of two topology structures and optimizes topology structures by finite element simulation to compare their no-load and load characteristics. Then, the influence of the stator yoke on the performance of the topology with series magnetic circuit is analyzed by equivalent magnetic circuit model and simulation. The results show that the quasi-yokeless structure and the yokeless structure have similar electromagnetic characteristics. However, the quasi-yokeless structure can keep the integrity of the stator, reduce the difficulty of processing and assembly, and minimize the influence of processing on motor performance. Finally, a prototype of the dual-rotor motor with quasi-yokeless stator is manufactured to validate the theoretical and simulation analysis.