The rotor structure of synchronous reluctance machines (SynRel) is conventionally retained mechanically by iron ribs. In this paper, a novel structure for high-speed synchronous reluctance rotor is presented. The novelty of this paper is the proof of a concept of SynRel machine without iron ribs. Structurally, the rotor iron lamination segments are embedded in an adhesive resin material with high temperature resistance and mechanical strength. Three four-pole SynRel machines have been designed with the target of improving motor torque, and compared for different ribs configuration. It has been shown that the proposed motor performs enhanced torque, power factor, and efficiency with respect to conventional SynRel with iron ribs. An extensive sensitivity analysis of the ribless rotor geometry is carried out, followed by both mechanical analysis and experimental over speed test to guarantee its robustness above the operating speed range. The manufacturing procedure of this novel rotor is introduced. Finally, the experimental results on both SynRel prototypes are presented, showing the increase in torque, power factor, and efficiency of the proposed solution. This paper is a first step toward the definition of a viable and novel solution of SynRel machines with improved performance.

In high power density machines, proximity loss presents an unavoidable obstacle due to its significant impact on thermal dissipation and insulation aging. To address the need for rapid and accurate proximity loss prediction, this study presents a novel methodology that employs a mesh-based magnetic equivalent circuit (MEC) for calculating proximity loss in electrical machines. Using an existing machine as an example, the proposed approach is applied to various scenarios, yielding results that demonstrate close agreement with both finite element analysis (FEA) and experimental results, validating its effectiveness. Notably, the technique exhibits high flexibility and can be extended to accommodate slots of various shapes. This innovative approach, which involves flux leakage calculation, represents a previously unexplored avenue and could potentially serve as a fundamental basis for expeditious AC loss calculations.

Resolver is widely used for angle and speed detection in electric vehicle drive application. Resolver generates angular position related voltage signals from sine and cosine windings, induced by high-frequency excitation signals. Due to the imperfect resolver installation, post-processing circuits and manufacturing tolerance, the inevitable amplitude imbalance error, offset error and non-orthogonal error might occur, which influences the angle accuracy from resolver to digital conversion (RDC) results. In order to improve accuracy and calibrate the resolver error, adaptive filter is proposed to remove DC offset errors, and a double second order generalized integrator frequency-locked loop (DSOGI-FLL) based RDC method is proposed to solve the imbalance amplitude error and achieve good frequency tracking. At last, third-order rational fraction polynomial approximation (TRFPA) are used to reconstruct the angle signals. Since the system has error suppression capabilities, the hardware cost of RDC can be further reduced. Both simulation and experimental results demonstrate the good dynamic tracking capability and error suppression capability. The proposed solution can be easily integrated an 'add-on' system to any resolvers based permanent-magnet synchronous motor (PMSM) system.

This study introduces a novel method to rapidly estimate the circulating current between the strands in electrical machines. By utilizing mesh-based magnetic equivalent circuit (MEC), key parameters of each strand are obtained based on their positions in the slot and used for circulating current calculation. The modelling and calculation process of the proposed method is demonstrated using a permanent magnet synchronous machine (PMSM) as baseline. The results calculated from the proposed method closely align with those from finite element analysis (FEA) and are further supported by experiments conducted on a segment of the stator, validating the effectiveness and efficiency of the proposed method. Notably, the proposed technique is applicable for various slot shapes and machine types, serving as a powerful tool for optimizing winding to minimize AC losses.

The synchronous reluctance machine is well-known for its highly nonlinear magnetic saturation and cross-saturation characteristics. For high performance and high-efficiency control, the flux-linkage maps and maximum torque per ampere table are of paramount importance. This study proposes a novel automated online searching method for obtaining accurate flux-linkage and maximum torque per ampere Identification. A limited 6 × 2 dq-axis flux-linkage look-up table is acquired by applying symmetric triangle pulses during the self-commissioning stage. Then, three three-dimensional modified linear cubic spline interpolation methods are applied to extend the flux-linkage map. The proposed golden section searching method can be easily implemented to realize higher maximum torque per ampere accuracy after 11 iterations with a standard drive, which is a proven faster solution with reduced memory sources occupied. The proposed algorithm is verified and tested on a 15-kW SynRM drive. Furthermore, the iterative and execution times are evaluated.

Synchronous reluctance machines are considered a cost-effective solution for several industrial applications and present potential efficiency benefits compared to induction motors. In industrial applications, power supply oscillations can lead to short-term disturbances that can affect the drive operation; therefore, the control must be robust to guarantee high efficiency and service continuity. The focus of this study was to identify the speed boundaries considering different values of applied DC-link voltage, taking into account the highly nonlinear magnetic behavior of the machine and its cross-coupling characteristics. In addition, a comprehensive carrier-based implementation of a pulse width modulation strategy was proposed to achieve optimal efficiency in both the machine and converter, which is essential in the presence of “weak” grids. The proposed technique was demonstrated to meet the desired reference torque and rated speed, even during DC-link voltage drops (up to 7.4% of the rated voltage). The proposed methodology was experimentally validated on a 90 kW SynRM drive with a broader modulation range and higher efficiency. This work considered several different supply voltage levels to assess the stability and continuity of torque output and further proved the proposed method.