## 1 Introduction  
In the face of security threats in the non-traditional climate change crisis, it has become an international consensus to advance the climate governance process through global cooperation. Improving industrial energy efficiency is one of the most effective ways to combat climate change [1]. As far as the motor industry is concerned, the high-efficiency motor has become the focus of attention. Permanent magnet synchronous motor (PMSM) is widely studied and used for its high efficiency [2; 3; 4]. However, PMSM needs permanent magnets affected by critical minerals such as rare earth and are a scarce resource with relatively high cost. Therefore, to further reduce energy consumption, synchronous reluctance motors with more straightforward structure and lower cost without permanent magnets have attracted more and more scholars' attention [5; 6; 7; 8; 9]. However, compared with permanent magnet synchronous motor, the torque characteristics of SynRM need to be improved, especially torque ripple. One of the main reasons for the large torque ripple of the SynRM is the spatial harmonic interaction of magnetic motive force caused by stator current and rotor geometry [10; 11; 12]. In terms of ontology design and optimization, previous studies have shown that the design parameters of the SynRM have a significant influence on the torque ripple [13; 14; 15; 16]. The hotspot of scholars' research mainly focuses on the shape and position of flux-barriers and the combination form of rotor silicon steel sheet during stacking [17; 18; 19]. [PERSON] suppressed the 10 th and 20 th harmonics to reduce the torque ripple by changing the end angles or salient pole angles of the flux barriers [14]. Furthermore,Nicola [PERSON] studied the influence of the flux-barrier angles between the flux-barrier ends and \(q\)-axis on torque ripple and proposed an analysis model, which can quickly select the flux-barrier angles to design a SynRM with minimum torque ripple [20]. However, not all MMF harmonics are considered to simplify the model. Reference [21] proposed that the specific torque harmonics can be eliminated by different flux-barrier geometry, and the corresponding torque harmonics of other geometry can be compensated by combining the flux-barriers of different geometry. Two laminates with different flux-barrier end angles are laminated to form a rotor. However, it makes the design more difficult because it needs to optimize these two laminates separately. Therefore, another method is also proposed to reduce the torque ripple in ref. [21], that is, two different flux-barrier-end angles are used on the same stack. Reference [22] also proposed the method of using asymmetric flux-barriers and a combination of different laminates to reduce the torque ripple. Nevertheless, motors designed by this method are more challenging to manufacture. Some scholars choose to use algorithms to optimize motor torque performance. References [19; 23; 24] introduces the automatic design process of SynRM multi flux barriers rotors based on finite element analysis and multi-objective genetic optimization. The design results show that the improved system can be implemented in a reasonable time, but not all rotor design degrees of freedom are beneficial to the system performance. Reference [7] trained nonlinear regression or alternative models for average torque and torque pulsation by using Bayesian regularization back-propagation neural networks. Next, multi-objective genetic algorithm is used to find the empirical Pareto frontier solution, and the analytic ellipse constraint is used to encapsulate the optimal solution. However, due to the problem of multi-variables and multi-constraints, swarm intelligence optimization algorithm is easy to fall into local optimization or has the problem of slow convergence speed in the process of motor optimization. Literature [12] presents a step-shaped flux-barriers rotor structure to reduce the torque ripple using the conformal mapping method and the magnetic equivalent circuit.