This paper proposes and analyzes magnetic field modulation machines adopting non-uniform permeance modular stator design. Distinct from conventional uniform permeance topologies, the presented design introduces target permeance harmonics via rearranging modulation blocks while keeping air-gap length and PM arc coefficient constant for fair comparison, to realize multi-harmonic coordination and high modulation ratio simultaneously. First, theoretical torque calculation is conducted to establish the “2+2” non-uniform permeance modular structure, which boosts output torque by enriching usable working harmonics. On this basis, a semi-analytical air-gap flux density calculation framework is developed to guide the stator tooth positioning of the subsequent “3+1” modular configuration, which further increases the modulation ratio via targeted harmonic injection for torque improvement. Operating performances of the two structures are evaluated by magnetic energy analysis and finite element simulation. Lastly, a “3+1” prototype is fabricated for experimental validation. Results verify the effectiveness of the proposed design framework. In addition to achieving a higher average torque, this topology also introduces inherent performance trade-offs. The parasitic harmonics intensify low-order radial forces, aggravating low-frequency vibration, while also increasing the alternating flux harmonics and consequently raising iron losses.
With the transformation of the energy structure, battery energy storage systems (BESS) are being expanded into multi-BESS (MBESS) to meet application demands. However, current consensus-based MBESS energy management strategies increase the system's equivalent cycling intensity and undermine its sustainability, accuracy, and operational safety due to communication delays. Accordingly, this paper proposes an echelon management strategy based on fixed-time proportional optimal consensus (FTPOC). First, an echelon optimization model is established to ensure operational sustainability by balancing aging and adjustable capacity. Moreover, the model also lowers the equivalent cycling intensity by reducing the number of activated battery units. Second, the objective function of the optimization model is transformed into an FTPOC; its fixed-time convergence and proportional consensus properties under delays are theoretically proved, and a practical parameter design method is provided. Finally, a complete FTPOC-based strategy is developed by incorporating all constraints of the optimization model. This strategy eliminates steady-state errors caused by delays and introduces explicit output constraints to prevent power over-allocation. The complexity of the proposed strategy and its adaptability under practical conditions are also discussed. Simulation and experimental results demonstrate the effectiveness of the proposed strategy in reducing activated battery units and achieving aging-aware power allocation.
Flux-switching permanent magnet (FSPM) machine experiences a relatively severe vibration and noise compared to other permanent magnet machines. This paper investigates the electromagnetic vibration response of a 12 slot 10 pole FSPM machine. Firstly, the air-gap magnetic flux density and the corresponding radial electromagnetic force density are calculated. Then the analytical modal analysis is conducted and combined with the calculated force density harmonics to calculate the electromagnetic vibration response in both no-load mode and load mode. By the air-gap field modulation theory and Maxwell tensor method, the sources of the prominently contributing radial electromagnetic force density harmonics are identified. To suppress the electromagnetic vibration response, the rotor is reshaped as notching rotor, y = kr|x| rotor and y = arx2 rotor to suppress the identified radial electromagnetic force density harmonic. The suppression effect is analyzed theoretically and y = arx2 rotor is proven to be able to realize the largest suppression of vibration. The proposed methodology forms a systematic identification–tracing–suppression framework that uniquely links air-gap flux density harmonics to vibration response, offering new physical insight and a targeted design rationale for low-vibration FSPM machines.
The Hybrid Rotor Asymmetric Permanent Magnet Synchronous Machines (HR-APMSMs) are known for the integration of two different rotor types, one with permanent magnet (PM) and one with pure reluctance (REL) torque. This integration enables the maximization of torque density by employing the magnetic-field-shifting (MFS) effect using a mechanical offset angle between rotor segments. However, existing analytical models and optimization studies do not capture how rotor hybridization and MFS jointly shape the dynamic operating characteristics of the machine, leaving the full operating envelope of HR-APMSMs unexplored. To address this gap, this paper introduces the novel shifted-reluctance-axis DQ-frame (SRA-DQ) model that considers the combined effects of rotor hybridization and MFS on the machine's operation in both maximum-torque per-ampere (MTPA) and field-weakening (FW) regions. By this means, various critical operation characteristics such as the MTPA trajectory, the Zero-Torque (ZT) trajectory and the Zero Flux (ZF) point are mathematically determined. Furthermore, the model's accuracy has improved by adding the effect of magnetic nonlinearities through the support of finite-element analysis (FEA). Upon the established SRA-DQ modeling method, a new multi-objective/multi-constraint design optimization strategy is proposed to co-optimize the MTPA and FW performance parameters. Compared with existing literature, the obtained performance characteristics demonstrate a significant improvement in torque density, while FW capability is considered as a key objective in the optimization process. Finally, a 3.8-kW prototype HR-APMSM is built and tested, confirming strong agreement between the predicted and measured results at MTPA and FW operation.
Owing to the restricted sampling period, using continuous-time sliding mode control methods to ensure the convergence of the permanent magnet synchronous motor (PMSM) drive is a prominent challenge in practical implementation. In order to handle such one issue, a discrete-time second-order sliding mode control approach is put forward in the paper. Through the rigorous Lyapunov theory based analysis, the convergence and anti-disturbance capability of the investigated PMSM drive control system are guaranteed in the discrete-time domain, which can provide a guidance for the adjustment of control parameters. Finally, the experiments by comparing the proposed control scheme with other three existing control methods are made on a real-world PMSM drive platform. The comparative experimental results are given to validate the effectiveness and advantage of the proposed approach in terms of dynamical and anti-interference performances of the speed loop.
