A method for predicting the electromagnetic noise of a permanent-magnet motor based on the coupling of electromagnetic force and modal is proposed. Firstly, a theoretical analysis and finite element method are combined to establish an electromagnetic force analysis model for a 6-pole 36-slot permanent-magnet motor used in vehicles. The spatial order and frequency characteristics of the electromagnetic force are analyzed. Then, the modal array of the motor is calculated using the finite element method, and the main sources of the motor vibration noise are predicted by combining the electromagnetic force with the modal frequency array of each order. Finally, a vibration noise multiphysics simulation analysis model is established using the finite element method, and the electromagnetic noise is calculated. The simulation results are consistent with the predicted results, verifying the effectiveness of the analysis method.

The electrification of agricultural machinery has become an important trend. Active Disturbance Rejection Control (ADRC) shows considerable potential in agricultural motor control due to its low model dependence and strong anti-disturbance capability. However, the Extended State Observer (ESO) of traditional ADRC is limited by bandwidth, making it difficult to effectively capture high-frequency impact disturbances such as torque fluctuations during straw cutting, which results in reduced efficiency and increased energy consumption. To address this, this paper proposes an improved ADRC scheme: designing a Super-Twisting Extended State Observer (STESO) by integrating Super-Twisting technology to enhance disturbance observation capability; incorporating a Quasi-Proportional Resonant (QPR) controller into the Error Feedback Control Law (SEF) to compensate for the shortcoming of disturbance suppression beyond ESO bandwidth; and proposing a decoupling strategy to reduce the difficulty of parameter tuning and optimize control performance. Simulations and experiments on the Permanent Magnet Synchronous Motor (PMSM) of an automatic seeder demonstrate that the proposed method can effectively suppress various disturbances, reduce speed regulation errors, and not deteriorate dynamic responses.

To enhance the electromagnetic performance of flat-wire permanent magnet synchronous motors, three different groove structures were designed for the rotor, and a multi-objective optimization algorithm combining a genetic algorithm (GA) with the TOPSIS method was proposed. Firstly, an 8-pole 48-slot flat-wire motor model was established, and the cogging torque was analytically calculated to compare the motor’s performance under different groove schemes. Secondly, global multi-objective optimization of the rotor groove dimensions was performed using a combined simulation approach involving Maxwell, Workbench, and Optislang, and the optimal rotor groove size structure was selected using the TOPSIS method. Finally, a comparative analysis of the motor’s performance under both rated-load and no-load conditions was conducted for the pre- and post-optimization designs, followed by verification of the mechanical strength of the optimized rotor structure. The research results demonstrate that the combined optimization approach utilizing the genetic algorithm and the TOPSIS method significantly enhances the torque characteristics of the motor. The computational results indicate that the average torque is increased to 165.32 N·m, with the torque ripple reduced from 28.37% to 13.32% and the cogging torque decreased from 896.88 mN·m to 187.9 mN·m. Moreover, the total distortion rates of the air-gap magnetic flux density and the no-load back EMF are significantly suppressed, confirming the rationality of the proposed motor design.

As fuel cell vehicles have broad development prospects, improving the performance of their air compressors is crucial for the normal and efficient operation of onboard fuel cells. To improve the performance of the air compressor and solve the contradictory relationship between the pressurization capability and efficiency of the impeller, this study proposes a method combining an approximation model and a multi-objective whale optimization algorithm. First, three-dimensional numerical models of the single-flow passage and the full compressor flow passage in the impeller were established, and the accuracy of the numerical calculations was verified using open-test-case compressors. Then, choosing the pressure ratio and isentropic efficiency as the optimization objectives, sensitivity analysis of the structural parameters of the impeller was conducted via Latin hypercube sampling, and surrogate optimization models were constructed using the least squares method for designing and setting the typical operating conditions for the impeller. Finally, the whale optimization algorithm, which is superior in impeller optimization compared to genetic algorithms, was employed to derive the Pareto solution set. Compared to the original impeller, the optimized impeller exhibited improvements in the pressure ratio as well as isentropic efficiency for the single-flow passage as well as full-model configurations. Under design conditions, the pressure ratio and isentropic efficiency increased by 5.5 % and 1.4 %, respectively, whereas under typical operating conditions, they improved by 3.6 % and 4.1 %, respectively. In addition, the three-dimensional flow characteristic analysis revealed reductions in the internal losses and recirculation within the optimized impeller. Thus, we can conclude that the proposed optimization method effectively enhances the overall performance of the fuel cell vehicle compressors.

In this study, a novel air bearing design based on a microgroove structure with a reverse fixed configuration is proposed to improve the bearing load carrying capacity, stability, and operating efficiency, while reducing the frictional torque and micromotion wear during startup. First, this paper proposes a novel air bearing design to optimize the pressure distribution of the air film by opening circumferential microgrooves on the flat foil, improve the gas flow by channeling the air flow, increase the stiffness of the air film and reduce the leakage rate, so as to enhance the bearing load carrying capacity. Secondly, to address the micromotion wear caused by small sliding between the foils due to the dynamic phase difference in the traditional design, the reverse fixation configuration of the flat foil and wave foil is proposed. On the basis of the above, it is verified by MATLAB numerical simulation and experiment. The results show that the improved air bearing exhibits higher load carrying capacity, significantly lower friction torque, good start-stop performance, and improved stress distribution and thermal expansion stability of the system. This indicates that the design has significant advantages in improving bearing load carrying characteristics, reducing friction loss and extending service life, and has a wide range of application prospects, especially suitable for high load and high speed equipment.

The built-in V-shaped permanent magnet motor can effectively utilize reluctance torque to improve torque density, but there is also a problem of large torque ripple causing high vibration noise. This article proposes a rotor structure with four magnetic isolation holes to reduce torque ripple in V-shaped built-in permanent magnet motors. Firstly, a finite element analysis model of the built-in V-shaped permanent magnet motor is established. The influence of slot width, rotor rib width, and magnetic bridge parameters on the torque of the permanent magnet motor was studied through parameterized scanning, and an optimization scheme was selected. Then, the position and size of the magnetic hole were optimized through an adaptive single-objective algorithm. Compared with the ordinary built-in V-shaped structure, the torque ripple of the built-in V-shaped permanent magnet motor with four magnetic isolation holes is reduced from 17.7% to 6.7%. The proposed internal V-shaped rotor structure with magnetic isolation holes and the optimization method can effectively reduce torque ripple, thus effectively solving the problem of vibration noise caused by torque ripple.