In order to weaken the torque ripple caused by cogs torque and increase the output torque of permanent magnet synchronous motor, this paper proposes a multi-objective optimization method of permanent magnet synchronous motor based on Improved Multi-Objective Salp Swarm Optimization Algorithm (IMOSSA) and Spearman correlation analysis. Firstly, the improved strategy of Multi-Objective Salp Swarm Algorithm (MOSSA) was proposed, and the effectiveness of the improved algorithm was further verified by the performance test of the algorithm. Then, the motor simulation model was established, and the high correlation parameters were filtered out by Spearman correlation analysis. The response surface model was established by Response Surface Method (RSM), and the regression equation was given. The IMOSSA was used for iterative optimization. Through optimization, the experimental results show that under the premise of meeting the efficiency design requirements, the average output torque of the motor is increased by 21.35%, the torque ripple and cogging torque are reduced by 45.04% and 39.17% respectively, which verifies the effectiveness and feasibility of the proposed method. 

Multi-objective optimization of permanent magnet motor based on Improved Salp Swarm Algorithm and Spearman correlation

Abstract In order to further improve the output torque and stability of the external rotor permanent magnet synchronous motor, a double‐layer non‐uniform Halbach external rotor permanent magnet synchronous motor (DNH) structure is proposed and optimised. Finite element models of DNH and other structures are established to compare the electromagnetic characteristics of these motors and verify the superiority of the proposed structure. Secondly, the multi‐objective whale optimisation algorithm is improved, and the algorithm is tested by test function to verify the improvement effect. Further, the Spearman correlation of the parameters is calculated, and the parameters are layered. The first layer parameters are optimised by the improved multi‐objective whale optimisation algorithm, and the second layer parameters are optimised by parameter scanning. Finally, the motor performance of the initial scheme, single layer optimisation scheme, and hierarchical optimisation scheme is compared by simulation. The simulation results show that the hierarchical optimisation method is superior to the single layer optimisation method. By comparing with other schemes, the performance advantages of hierarchical optimisation DNH in terms of average output torque, cogging torque, torque ripple, permanent magnet cost and other parameters are proved, as well as the effectiveness of the optimisation method. 

Design and multi‐objective optimisation of double‐layer non‐uniform Halbach external‐rotor permanent magnet synchronous motor

For compensating the gap of present investigations, which did not consider the effect of skin depth before, a novel method is also proposed to obtain the eddy current force. At the beginning, the separating principle of eddy current separator (ECS) is given. Then, based on boundary conditions and the eddy current equations, the internal magnetic flux density, eddy current density and eddy current force density of non-ferrous metal are deduced. By calculating the double integral of eddy current density, the internal eddy current of non-ferrous metal is achieved. The theoretical calculation method (TCM) for solving the eddy current force in the process of non-ferrous metal sorting is proposed. Moreover, to verify the correctness of TCM, taking 24-pole and 30-pole magnetic roller as examples, the finite element models of static and transient magnetic field are established respectively. Additionally, the correctness of TCM is proven by finite element method (FEM) when the x-axis and y-axis component of eddy current force is calculated. At the end, by the theoretical analysis and derivation derived in this paper, based on the relationship between the relative position of N and S poles of the magnetic roller and non-ferrous metal, the internal eddy current force are analyzed by the consistency between the direction of the internal magnetic flux density and the eddy current of non-ferrous metal. The influence of the size relationship between the non-ferrous metal and a single magnetic pole on the separation effect is discussed.

Research on eddy current and force of non-ferrous metal in eddy current separator

In view of the problem of high energy consumption of ordinary hydraulic brick presses, the scheme of energy-saving transformation is proposed to replace the asynchronous motor with AC permanent magnet synchronous servo motor. The simulation models of the ordinary hydraulic brick press and the reformed servo direct drive pump-controlled hydraulic brick press are established in AMESim, and the energy consumption simulation and analysis are carried out. The results show that the modified servo direct drive pump-controlled hydraulic brick press is 20.7% more energy-saving than before the transformation. The reasons for energy saving lies in that, compared with the ordinary hydraulic brick press, the servo direct drive pump-controlled hydraulic brick press saves overflow loss in the pressure holding stage and reduces the dormant loss in the dormant stage.

Research on energy saving of hydraulic system of hydraulic brick press

Recently, solar energy has been developed and widely utilized in photovoltaic system networks and provided a significant clean energy supply for the world. Additionally, the photovoltaic system is an essential module to generate the electrical power in energy supplement systems. However, existing photovoltaic systems are vulnerable to the affection of climate environment and may cause uncountable economic loss and decrease the power generation for power supply system. Therefore, the development for faults recovery strategies are necessary in photovoltaic system. Existing methods are concentrated on utilizing the units control detection method to identify the faults points and cause numerous identification costs. In this paper, we utilize the long short-term memory network (LSTM) to achieve photovoltaic system faults detection task, which can enhance the detection accuracy and reduce the computation cost for identifying procedure. From our extensive experiment results, we can conclude that our proposed method achieves more than 90% detection accuracy with reasonable detection costs through comparing with existing detection methods. 

Research on photovoltaic system faults detection strategy based on memory network

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Research on eddy current and force of non-ferrous metal in eddy current separator

Research on energy saving of hydraulic system of hydraulic brick press

Research on photovoltaic system faults detection strategy based on memory network