This paper presents a systematic comparative design study of permanent magnet assisted synchronous reluctance (PMaSyR) machines for a light traction application aimed at considering an holistic approach for a given outer envelope and cooling system specification. Electromagnetic, structural and thermal aspects are all accurately considered in a computationally efficient manner using a hybrid analytical-finite element (FE) design approach. The SyR machine geometries providing the maximum torque with increasing number of poles are identified and their performance deeply investigated with full FE analysis. The study has been carried out considering several requirements in terms of base and maximum speeds with the aim of drawing general design considerations. Results reveal that the optimal pole number from a torque perspective depends on the considered maximum speed. The reasons behind this behavior are fully investigated as well as how and why the optimal geometries change. The optimal SyR machines are then compared also considering the insertion of permanent magnets within the rotor slots with the aim of maximizing the constant power speed range. The rationales behind the selection of the machine to manufacture are then outlined including aspects related to efficiency and demagnetization under the worst short circuit condition in the entire torque-speed range. The optimized machine (after a FE-based design refinement) has been manufactured and tested on an instrumented test bench validating the proposed design approach and the deduced design insights.

This paper deeply investigates the torque ripple reduction of synchronous reluctance motors (SynRel), considering the impact of the current harmonic injection (CHI) on the total losses by employing d -axis, q -axis, and dq -axes injections. An in-depth analysis of the torque behavior has been carried out by means of finite element (FE) simulations, highlighting the dependence of the torque ripple on the magnetic saturation. The current reference trajectories are derived based on the torque ripple model taking into account the magnetic saturation, while the total loss is minimized by considering the copper and iron losses by the FE-based or experimental evaluation to select the optimal solution. The effectiveness of the torque ripple reduction technique using different CHIs is demonstrated by the FE simulations and experiments for SynRel 15kW prototype.

The High-Frequency Injection (HFI) method is commonly used for sensorless control of Synchronous Reluctance motors (SynRMs) at low speeds. Injecting a high-frequency (HF) signal in a predefined direction, referred to as the $d$ -axis, and further demodulating the excited signal in the $q$ -axis is a popular sequence for SynRM position tracking. Injection in the $q$ -axis is not usually considered due to its potential to increase torque ripple. This paper proposes a generalized HF pulsating voltage injection approach for sensorless control of SynRM. This approach allows for arbitrary selection of injection strategy and covers the injection and demodulation procedures in $d$ & $q$ axes in detail. Special attention is given to determining the amplitude of the injection voltage, which can extend the usage range of HFI and support sensorless control at high speeds. The effectiveness of the proposed structures is experimentally verified using SynRM 15kW. During system validation, extra care is taken to investigate the overall system efficiency and vibration levels, including torque ripple issues. This solution contributes to the advancement of sensorless control for SynRM drives.

This paper presents an accurate model identification method for the synchronous reluctance machine (SynRel), considering the nonlinear magnetic behavior and spatial harmonics. The availability of the high-fidelity magnetic model is essential for high-performance control and modeling the vibro-acoustic behavior of the electric drive, allowing to predict not only the average torque but also the torque ripple behavior versus rotor position. The magnetic coenergy variation is calculated based on the flux linkages in order to yield the torque ripple. During the identification, the current disturbances introduced by the spatial effects and the inverter nonlinearities are properly suppressed by the merged proportional-integral (PI) controller with a repetitive technique. Besides, the inverter nonlinearity and digital control effects are carefully addressed to improve identification accuracy. The effectiveness of the proposed identification method is demonstrated by the comparison of the finite element (FE) simulation results and experiments for two SynRel prototypes.

Various electrical drive systems have widely implemented the classical cascaded field-oriented control (FOC) topology, including speed loop, current loop, and modulation. On the other hand, modulated model predictive control (M ² PC) has been employed recently for different applications for faster dynamic response and better power quality. The FOC topology's speed and current control loops can be merged to simplify the control system structure and improve the system dynamics. Therefore, a non-cascaded speed loop controller employing M ² PC for permanent magnet synchronous motors (PMSMs) is introduced. The required simulation work has been developed to analyze the algorithm performance compared to PI, non-cascaded MPC, and M ² PC controllers. In addition, it has been applied practically through a dedicated testing rig, and results are investigated showing its merits including harmonic content, dynamic behavior, and robustness against parameter mismatch.

To improve the design of electric drives and to better predict the system performance, numerical simulation has been widely employed. Whereas in the majority of the approaches, the machines and the power electronics are designed and simulated separately, to improve the fidelity, a co-simulation should be performed. This paper presents a complete coupled co-simulation model of synchronous reluctance machine (SynRel) drive, which includes the finite element model of the SynRel, the power electronics inverter, the control system, and application examples. The model of SynRel is based on a finite element model (FEM) using Simcenter MagNet. The power electronics inverter is built using PLECS Blockset, and the drive control model is built in Simulink environment, which allows for coupling between MagNet and PLECS. The proposed simulation model provides high accuracy thanks to the complete FEA-based model fed by actual inverter voltage. The comparison of the simulation results with experimental measurements shows good correspondence.