This letter presents a sensorless control strategy using the novel detection coil for permanent magnet synchronous motor with fractional slot concentrated winding (FSCW). In order to eliminate the armature component in the coil voltage, the detection coil distribution is determined based on the analysis of synchronous inductance and leakage inductance for FSCW machines. Hence, the rotor position and angular velocity are estimated from the terminal voltage of detection coil without any knowledge of motor parameters. Both finite-element analysis results and experiments are carried out to prove the effectiveness of the proposed method at steady and transient states.

Deadbeat predictive current control (DPCC) demonstrates excellent dynamic performance. However, in practical applications, its effectiveness is degraded by parameter mismatches and inverter nonlinearities. Among the various improvement methods addressed for these issues, incremental model-based DPCC (I-DPCC) achieves zero static current error with a low computational burden but suffers from instability under parameter variation, especially when applied to interior permanent magnet synchronous motors (IPMSMs). In this paper, a robust I-DPCC (RI-DPCC) combining feedforward control is proposed for IPMSM, with an adjustable stable operation range that can be extended to twice the actual inductance or even larger. To further improve the robustness of dynamic performance, an inductance correction method is introduced to track the variation of inductance during dynamic processes. Thus, the current commands can be well tracked even when significant inductance variation occurs. With sufficient voltage margin, the dynamic processes under mismatched inductance can be shortened to four control periods. Finally, experimental results validate the effectiveness of the proposed method.

This paper presents an improved rotor positionestimation method for surface permanent magnet synchronousmotor (SPMSM) using a low-resolution Hall-Effect sensor. Firstly,an observation function is proposed to detect the speed variation,and a novel correction method based on optimization processis proposed to identify and correct the deviation angle causedby sensor misalignment. Then, an improved position observer isintroduced using a gain-scheduling controller to achieve betterperformance in both steady state and transient state. Theproposed method enhances the anti-perturbation and start-upcapability for SPMSM and compensate the misalignment effectof Hall-Effect sensors. Experimental results are demonstrated toverify the effectiveness of the proposed method.

This paper proposes the field separation theory for predicting the magnetic field of a quasi-Halbach array permanent-magnet motor considering the magnetization pattern and iron saturation. According to the proposed method, the air-gap field consists of a permanent-magnet field, winding current field, and equivalent saturation field. The equivalent permanent-magnet currents replacing the Halbach array with radial or parallel magnetization are introduced to obtain the linear analytical air-gap field of the permanent magnets. The winding current field relating to the slot shape and air-gap length can be directly determined using the linear analytical model. The equivalent saturation field is derived from the combination of the linear analytical model in the air gap and the magnetic circuit model in the iron region. The finite-element analysis of an 8-pole/9-slot Halbach array permanent-magnet motor and its prototype experiments are carried out to verify the effectiveness of the field separation theory, which is then used to analyze the harmonic magnetic field of Halbach array permanent-magnet motors to further improve the electromagnetic torque estimation. 

This paper proposes an asymmetric flux reversal permanent magnet linear machine (AFR-PMLM) with reduced leakage flux. By utilizing asymmetric permanent magnet excitation, the AFR-PMLM can effectively generate and fully exploit the second-order harmonic magnetomotive force (MMF), resulting in a substantial improvement in both thrust force density and power factor compared with conventional FR-PMLM. First, the machine topology and operation principle are introduced. Then, the thrust force generation mechanism under multi MMFs is analytically calculated based on MMF-permeance model. In addition, some electromagnetic performances, including open-circuit characteristics, thrust force performances and power factor are comparatively studied. It shows that the proposed AFR-PMLM with Halbach PM array can provide 7.2% higher average force than conventional AFR-PMLM under rated condition. Additionally, the power factor can be enhanced to more than 0.8 when the current density is 6 A/mm(2).

This article presents a comprehensive method to predict the electromagnetic losses in surface-mounted permanent-magnet (PM) motors based on a hybrid analytical model (HAM). HAM will significantly improve the calculation speed compared with finite-element method (FEM) while keeping great accuracy, making it a competitive alternative for the analysis and optimization of PM motors. As the accurate field distribution is the bias of electromagnetic losses prediction, the magnet loss, sleeve loss, and copper loss can all be accurately obtained from their vector potential distribution using HAM with small computational burden. As for iron loss, the improved Jiles–Atherton (JA) model is proposed to build the relationship between the loss and the magnetic field in the iron region from the perspective of energy conversion. The predictions of magnet loss, sleeve loss, and copper loss using HAM agree well with the FEM. The experiment on surface-mounted PM prototype demonstrates the high accuracy of iron loss calculation using the combination of the improved JA model and HAM.

This article proposed a nonlinear analytical model (NAM)-embedded optimal design procedure for permanent-magnet synchronous motors with an external rotor. Combined with the winding inductance calculation, a refined magnetic circuit is proposed for the analytical prediction of the electromagnetic performance. The stator nonlinearity, which is significant in torque prediction, is considered by using the conception of saturation current. Then, ant colony algorithm is employed for the multi-objective optimization for the great potential in global exploring. Finally, optimal design parameters are selected from the Pareto front. The effectiveness of the proposed optimization design method is verified by finite-element analysis (FEA) and experimental results of the manufactured prototype.

This article proposes two kinds of asymmetric flux reversal permanent magnet linear machine (AFR-PMLM) for long excursion application. By utilizing asymmetric permanent magnet excitation, the AFR-PMLM can effectively generate and fully exploit the second-order harmonic magnetomotive force (MMF), leading to a significant enhancement in thrust force density. First, the machine topology and operation principle are introduced. Then, the thrust force generation mechanism under multi MMFs is analytically calculated based on an improved MMF-permeance model, and further verified by finite element analysis. Various electromagnetic performances, including open-circuit characteristics, thrust force performances, and power factor, are comparatively studied. It shows that the proposed AFR-PMLM with consequent pole structure can provide 40.1% higher average force than conventional FR-PMLM under rated condition. In addition, it consumes only about 39.5% of the PMs volume while providing approximately 90.4% of the thrust force compared with switched flux PMLM. More importantly, the AFR-PMLM consumes only 1/80 PMs volume while achieving 75.0% of the thrust force density compared with conventional PMLM for a long excursion with 10 m. Finally, two prototypes of AFR-PMLM are manufactured for experimental validation.

With the trend toward transportation electrification, the power density of electrical machines faces ever-increasing requirement owing to the stringent limit of weight, especially for aerospace applications. Conventionally, the reliability of electrical machines in such safety-critical application is guaranteed by considerable safety margins, i.e., the over-engineering approach, which prevents electrical machines from reaching higher power densities and leads to a design conflict. This paper proposes a reliability-oriented design approach for low-voltage electrical machines by integrating model-based lifetime prediction into a multi-objective optimization process. Accelerated thermal degradation tests are carried out on mainwall insulation and turn insulation, then the thermal degradation model is built to predict the lifetimes, accordingly. Thermal lifetime models are developed at several lifetime percentiles for both continuous duty and variable duty applications. Finally, a feasible reliability-oriented multi-objective optimization platform is established, based on which a study-case electrical machine for aerospace application is designed and optimized. The prototype is manufactured to verify the optimized performances.

This article develops a scalable analytical model that builds a relationship between any surface-mounted permanent magnet (SPM) motor and a general motor with variable slot-opening and air-gap length, considering both the saturation effect and slotting effect. It can not only give the performance of the single SPM motor but also show internal connection among different SPM motors regardless of the motor power and dimension. To account for the iron saturation, the equivalent saturation current combined with simplified BH curves of iron is introduced to directly present the iron magnetic potential distribution without an iterative process. Thus, the proposed model can be used as the surrogate model in the motor design with little computation and provide great insight into the relationship among motors with different power and dimension. Both finite-element analysis and experiment are carried out to validate the proposed model.