In order to reduce electromagnetic noise of permanent magnet synchronous motors, it is necessary to analyze the modal of motor. In this paper, the modal of induction motor is studied by applying the key modal parameters such as the orthotropic material properties of core, contact stiffness factor, and the bearing stiffness. Compared with the actual modal test results finally, the modal simulation frequency of the motor error is kept within 5%.This method has guiding significance for modal simulation of similar structure motors.
In order to overcome the limitations of traditional dimensional design methods for motor product design, this paper uses a novel topology optimization strategy (TOS) based on normalized Gaussian network (NGnet) to re-optimize a mass-produced refrigerant compressor motor while considering both output torque and torque ripples. In order to enable the obtained structure can be processed, a method of topological separation suppression is adopted. The transient performance of the machine is analyzed by 2D FEA. The results show that the performance of the re-optimized model is significantly better than before. The improved TOS has a good application prospect in motor product design.
Estimating accurate torque and speed is critical to control the operation of permanent magnet synchronous motors (PMSM). But the temperature factors are usually neglected in existing studies, which degrades estimation accuracy. In this paper, a thermal-aware digital twin model is proposed for PMSM to estimate motor torque and speed with the motor temperature and d-q axis current and voltage. Firstly, the motor parameters related to torque and speed are extracted by the Spearman correlation coefficients. Moreover, the stator winding temperature is selected as the input feature. Secondly, a digital model based on BP neural networks (BPNN) is established to estimate torque and speed. Thirdly, the parameters of the BPNN model are optimized by the whale optimization algorithm to accelerate the convergence speed and avoid local optima. Finally, experimental results show that the mean square error (MSE) of the BPNN model considering the temperature factors is reduced by 8.3%, which verifies that there is an effect of temperature on the torque and speed estimation. The MSE of the proposed method is reduced by 11.7% on average, which confirmed the higher accuracy of the proposed method compared with the classical BPNN model.
Consequent-pole permanent magnet synchronous motors (CPPMSMs) have only half the number of permanent magnets (PMs) of PMSMs, which can significantly reduce the usage of PMs. This paper analyzes the influence of the rotor core of CPPMSM on the armature reaction field and the influence of stator teeth on the magnet field based on flux-modulation effect firstly. Then the radial force characteristics of the CPPMSM are analyzed in detail from the perspective of field harmonics based on the Maxwell stress tensor method and verified by finite element analysis. The results show that the armature reaction field has more harmonics due to the modulation of the rotor core of CPPMSM, and the order of radial force of CPPMSM and PMSM under the same pole-slot combinations differs by an integer multiple of the number of pole pairs. When the number of pole pairs of the motor is an integer multiple of the greatest common divisor (GCD) of the number of poles and slots, the lowest order of the radial force of CPPMSM is consistent with PMSM, but its frequency is lower. While it is a fraction multiple, the lowest order of radial force of CPPMSM will become lower, and its frequency will also become lower. These radial forces with lower order or lower frequency should attract the attention of motor designers.
Variable flux memory machines (VFMM) use magnetization and demagnetization manipulations to adjust machine voltage, achieving wide-speed high-efficiency operation. The machine magnetization state manipulation is a critical concern in the VFMM control. Thus, this article proposes an on-line magnetization state estimation and closed-loop control using the magnetization manipulation signals. The magnetization state manipulation requires voltage injection to create the manipulation current. The current shows non-linear response at different magnetization state because the current changes the magnets state and the machine saturation level. The flux change rate, which is calculated by the injected voltage and the current response, is affected by the non-linearity and utilized in the proposed method for the magnetization state estimation. The proposed magnetization state estimation achieves self-sensing characteristic because the signals in the estimation already exist in the magnetization state manipulation. Based on the estimated and the target magnetization state, the closed-loop magnetization state control is achieved by the voltage injection regulation.
Consequent-pole Permanent Magnet Synchronous Motors (CPPMSMs) have only half the number of permanent magnet (PM) of Permanent Magnet Synchronous Motors (PMSMs), which can significantly reduce the usage of PM. In previous papers, how the permanent magnet pole and core pole affect the torque characteristics of the motor has been analyzed, but how they affect the radial electromagnetic force of the motor has not been studied comprehensively. Firstly, based on the principle of magnetic field modulation, the influence of rotor structure on the armature reaction magnetic field and the influence of stator teeth on the permanent magnet magnetic field are analyzed. Secondly, based on the Maxwell stress tensor method, the characteristics of the radial electromagnetic force of CPPMSMs are studied in detail. Some exciting phenomena are found: When the polar logarithm of CPPMSM is an integer multiple of the greatest common divisor of the number of slots and poles, the minimum order of the radial electromagnetic force of CPPMSM is the same as that of PMSM, but the radial electromagnetic forces with more frequency are added; when the polar logarithm of CPPMSM is a fractional multiple of the greatest common divisor of the number of slots and poles, the minimum order of radial electromagnetic force of CPPMSM is lower than that of PMSM, and more radial electromagnetic forces with multiple frequencies are added. Then, the consistency of the characteristics of radial electromagnetic force and vibration is verified, through the vibration simulation of the motor. Finally, the accuracy of the analysis results is further confirmed by the vibration test of the prototype.
Due to the high loss density and thermal dissipation difficulty of high speed permanent magnet synchronous motor (HSPMSM), permanent magnet is prone to irreversible demagnetization at high temperature. Furthermore, overheating of the rotor will lead to the decrease of the strength and stiffness of shaft, elongation of shaft, etc, affecting the bearings suspension accuracy and stability, especially for the motor with magnetic bearings. To solve these problems, an improved radial and axial hybrid cooling system, greatly simplifying the ventilation cooling structure, is presented for a 70kW, 30000 rpm HSPMSM with magnetic bearings in this paper. The fluid field and temperature field calculation model are established by finite element software, and the fluid flow distribution in cooling system and the temperature distribution of the motor are both analyzed in detail. Finally, experiments with the prototype show that the improved hybrid cooling system has excellent cooling effect, and also show that the motor with rated speed can run stably for a long time under no-load and load conditions, whose efficiency is over 97%.
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