In this paper, a multi-objective optimization method is proposed to address the problem in the optimization process of the generator that only a specific index of a generator can be optimized to the neglect of other performance indices. Based on the equivalent magnetic circuit method, a mathematical model of the magnetic circuit of a radial-tangential combined permanent magnet pole generator is established, and the expression of the cogging torque including the pole offset angle is derived. The pole offset angle is proposed as the design variable, and no-load induction potential, air-gap flux density, and cogging torque are used as optimization targets. The relative optimal designs of permanent magnet generators are based on Pareto front statistics and defined parameter matching coefficients. Finally, a prototype is made based on the optimal structural parameters. According to the experimental results of the prototype, the correctness of the theoretical analysis and the effectiveness of the optimal design are verified.

The armature reaction of the hybrid excitation starter generator (HESG) under load conditions will affect the distribution of the main magnetic field and the output performance. However, using the conventional field-circuit combination method to study the armature reaction has the problem of low accuracy and inaccurate influencing factors. Therefore, this paper proposed a graphical method to analyze the armature reaction and a new type of HESG with a combined-pole permanent magnet (PM) rotor and claw-pole electromagnetic rotor. The analytical formula of the voltage regulation rate under the armature reaction was derived using the graphical method. The main influencing parameters of the armature reaction magnetic field (ARMF) were analyzed, and the overall output performance was analyzed using finite element software. On this basis, comparison analyses before and after optimization and the prototype test were carried out. The results show that the direct-axis armature reaction reactance, quadrature-axis armature reaction reactance, and voltage regulation rate of the optimized HESG were significantly reduced, the output voltage range of the whole machine was wide, and the voltage regulation performance was good.

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.

In addressing the challenges posed by the numerous rotor structure parameters and the difficulty in analyzing the air gap magnetic field distribution in interior permanent magnet (IPM) motors, and to enhance the performance of automotive IPM synchronous motors, this paper proposes a multi-objective optimization method based on sensitivity stratification. Firstly, sensitivity analysis is conducted on the positional and shape parameters of the rotor permanent magnets (PMs), and the parameters are stratified according to their sensitivity levels. Subsequently, distinct analysis and optimization methods are applied to parameters of different strata for dual-objective optimization, which aims to increase the amplitude of the air gap flux density and reduce its total harmonic distortion (THD). Moreover, the waveform of the air gap flux density is analyzed to propose a targeted arrangement of magnetic isolation slots, thereby further optimizing the magnetic field distribution. Meanwhile, the demagnetization conditions and influencing factors of the PMs under overload are analyzed to enhance their demagnetization resistance and determine the final structural parameters. Simulation results indicate that, with the application of the proposed optimization method, the fundamental amplitude of the air gap flux density is increased by 0.035 T and THD is decreased by 9.9% when the proposed optimization method is applied. This verifies the effectiveness and feasibility of the method.

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.

The coaxial parallel magnetic circuit dual-rotor hybrid excitation structure generator exhibits several advantages, including high output performance, a wide adjustment range, and excellent stability. This study introduces a topology for a parallel magnetic circuit hybrid excitation generator (PMC-HEG) that utilizes a combination of permanent magnet and electrical excitation. It features salient pole rotors and claw pole rotors, with the latter embedded with permanent magnets, sharing a common stator. The analysis of the rotor magnetic field is conducted using both the equivalent magnetic circuit method and the subdomain method. Through an examination of the generator’s electromagnetic performance, key rotor parameters related to optimization objectives are identified. Finite element simulation analysis is performed on the rotor parameters, employing various optimization algorithms to enhance the salient pole and claw pole rotors, focusing on the amplitude of the induced electromotive force and the distortion rate of the induced electromotive force as optimization targets. The final optimized parameter values are obtained. A prototype is fabricated and tested, with experimental results confirming the reliability of the optimization method. The optimized parallel magnetic circuit hybrid excitation generator demonstrates an increase in the amplitude of the induced electromotive force, an improvement in the fundamental wave of the induced electromotive force, a reduction in harmonic distortion rate, and a significant enhancement in overall output performance.