This work presents a hybrid biaxial pseudo-random high-frequency signal injection (Bi-PR-HFSI) strategy to suppress high-frequency (HF) torque ripple and electromagnetic (EM) vibration, thereby improving the low-speed sensorless control performance of SynRMs. The proposed method combines hybrid HF excitation with Bi-PR modulation, which helps redistribute spectral energy while suppressing discrete harmonic components in the HF current. Compared with conventional square-wave injection techniques, the injected hybrid voltage contributes to lower current components and minimizes HF torque ripple and EM vibration under injected frequencies. Despite the increased waveform complexity, the hybrid signal remains compatible with demodulation schemes, ensuring no additional computational overhead. Experimental evaluation on a 5.5 kW SynRM under fixed and PR injection conditions confirms that the hybrid voltage effectively smooths HF torque ripple and suppresses EM vibration across the injected frequency range. These results highlight the feasibility and effectiveness of the hybrid Bi-PR-HFSI method in improving motor performance for sensorless SynRM drives.

Aiming at preventing many undesirable consequences caused by excessive temperature rise, improving the thermal management capability of interior permanent magnet synchronous motor (IPMSM), and promoting the prosperous development of IPMSM in the field of transportation electrification, this article carries out an innovative research around the highly efficient, accurate, and practical temperature prediction technique. An improved three-dimensional hybrid thermal model (3D HTM) is proposed for the fast and exact prediction of the global temperature distribution of IPMSM. First of all, to adequately account for the complex structure of IPMSM in 3D space, the equivalent thermal region is reasonably subdivided by starting from the x-y plane and the cross-section in the z-axis direction, respectively. Next, on the basis of the partial differential equation of the heat flux, the general solution for the associated temperature distribution function is derived by reference to the specific distribution characteristic of the equivalent thermal region. Afterwards, the boundary condition is deduced depending upon the interface feature between neighboring equivalent thermal regions. And further, the smooth construction and solution of 3D HTM is accomplished by incorporating the finite element analysis, lumped parameter thermal network, and iterative strategy. Thereby, the prediction of the global temperature distribution of IPMSM under various complex operating conditions is successfully realized without being constrained by the operating scenarios. Meanwhile, 3D HTM possesses very impressive prediction speed and accuracy. In particular, compared to the currently popular numerical analysis tool (computational fluid dynamics, CFD), nearly 70.00% or more of the prediction cost, including time cost and storage cost, is saved; moreover, the prediction difference consistently stays below 4.00%, both for the temperature variation on the comparison path and for the maximum temperatures of critical elements. Ultimately, the validity, sophistication, and practicality of this research are strongly validated by simulation calculation, comparative analysis, and prototype experiment.

With the continuous upgrading of traditional manufacturing industries and the rapid rise of emerging technology fields, the performance requirements for the permanent magnet synchronous motors (PMSMs) have become higher and higher. The importance of fast and accurate electromagnetic thermal coupling analysis of such motors becomes more and more prominent. In view of this, the surface-mounted PMSM (SPMSM) equipped with unequally thick magnetic poles is taken as the main object and its electromagnetic thermal coupling analytical model (ETcAM) is investigated. First, the electromagnetic analytical model (EAM) is studied based on the modified subdomain method. It realizes the fast calculation of key electromagnetic characteristics. Subsequently, the 3D thermal analytical model (TAM) is developed by combining the EAM, the lumped parameter thermal network method (LPTNM), and the partial differential equation of heat flux. It realizes the fast calculation of key thermal characteristics in 3D space. Further, the information transfer channel between EAM and TAM is built with reference to the intrinsic connection between electromagnetic field and temperature field. Thereby, the novel ETcAM is proposed to realize the fast and accurate prediction of electromagnetic and temperature fields. Besides, ETcAM has a lot to commend it. One is that it well accounts for the complex structure, saturation, and heat exchange behavior. Second, it saves a lot of computer resources. It offers boundless possibilities for initial design, scheme evaluation, and optimization of motors. Finally, the validity, accuracy, and practicality of this study are verified by simulation and experiment.

The cross-coupling effects in synchronous reluctance motors (SynRMs) can lead to deviations in the actual high-frequency (HF) voltage values. During the use of high-frequency square-wave injection (HFSWI) methods, these deviations can cause rotor position errors, thereby reducing the control performance of the motor. To address this issue, this paper proposes a sensorless control strategy for SynRMs based on modified HF voltage equations. This approach effectively reduces rotor position error while improving stability and dynamic response speed. Firstly, a theoretical analysis is conducted on the rotor position error caused by the cross-coupling effect in traditional algorithms. Then, based on the experimentally measured HF response current, modified HF voltage equations are proposed. Correspondingly, improved observer structures are designed for both d-axis HFSWI (d-HFSWI) and q-axis HFSWI (q-HFSWI) methods using the modified voltage equations. Finally, the effectiveness of the proposed sensorless control strategy is verified by simulations and experiments using a 5.5 kW SynRM model and drive platform.

To ameliorate the comfortable quality of vehicles using air suspensions, based on a three-dimensional model of a vehicle, an optimal control approach of FC-ML using combined control of the fuzzy control (FC) - machine learning (ML) has been studied to control the active damping values in air suspensions. The FC-ML’s efficiency has been simulated and analyzed under two road types of rigid road and soft ground with their different rough surfaces at various velocities of the vehicle. The investigation results present that both FC and FC-ML ameliorate the vehicle’s comfortable quality better than air suspension without control. Besides, under different working simulations of the vehicle, FC-ML ameliorates the vehicle’s comfortable quality better than FC. Especially, the values of the root-mean-square vehicle body’s accelerations in the vertical, pitching, and rolling directions with FC-ML are lower than FC by {15.4%, 23.4%, 14.5%} on the rigid road and {12.4%, 22.2%, 17.9%} on the soft ground with their combined rough road and very rough road. This means that this new combined control approach of FC-ML ameliorates the comfortable quality of vehicles better than FC, thus, it should be applied to vehicles using different suspension systems to further ameliorate the comfortable quality.

This work proposes a hybrid d-axis high-frequency signal injection (HFSI) technique for low-speed sensorless control of SynRMs, aiming to regulate the high-frequency (HF) current and suppress HF torque ripple and electromagnetic (EM) vibration. The proposed technique employs a hybrid sinusoidal excitation, which, under the same current amplitude, generates lower HF current and HF torque components than the conventional sinusoidal and square-wave HFSI techniques, as validated through power spectral density (PSD) analysis. Benefiting from its intrinsically lower HF injection noise characteristics, the hybrid signal further achieves reduced HF noise when combined with pseudo-random signal injection approach, thereby outperforming sinusoidal and square-wave pseudo-random signal injection methods. Although the injected hybrid HF signal exhibits a complex waveform, this complexity is effectively managed during signal demodulation without increasing the computational burden of the sensorless control algorithm. Experimental tests using both fixed-frequency and pseudo-random d-axis HFSI approaches with sinusoidal, hybrid and square-wave signals on a 5.5 kW SynRM demonstrate that the proposed hybrid signal significantly mitigates HF torque ripple and EM vibrations, thereby enhancing the sensorless control performance of the SynRMs.

Now, interior permanent magnet synchronous motors (IPMSMs) are developing rapidly toward higher power density and wider speed range. In this process, it is particularly critical to quickly and accurately estimate the rotor mechanical strength for the IPMSM in the limit state. For this purpose, in this article, an analytical model of the maximum mechanical stress in the rotor for the IPMSM considering thermal effects is investigated. First, the temperature calculation model is innovatively developed based on the improved thermal domain method. Thus, the accurate acquisition of the temperature variation function on each component is accomplished. In the next step, the center-of-mass equivalent circular method is introduced to subdivide the solution domain for the complicated hybrid magnetic circuit structure. After that, on this basis, the forces on each equivalent solution domain are analyzed by considering the effect of thermal stresses while combining with the thick-walled cylinder theory. The general solution of the stress-displacement function on each equivalent solution domain is obtained. Furthermore, the boundary condition between the neighboring equivalent solution domains is established and solved. In this way, the rapid construction and accurate solution of the analytical model of the maximum mechanical stress in the rotor considering thermal effects is completed. Consequently, the fast and accurate estimation of the maximum mechanical stress in the rotor of the IPMSM considering thermal effects is well achieved. Finally, the validity and engineering practicality of this study are verified by simulation and experiment.

Sine-wave drive and square-wave drive are two common motor control strategies. This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance motors (SynRMs) under these two drive methods, and comparatively analyzes the vibration phenomena induced by electromagnetic forces under different drive methods. It aims to provide an effective tool for predicting the distribution of electromagnetic force waves in SynRMs, while exploring the influence of drive modes on their vibration characteristics. The study focuses on a 4-pole, 36-slot 5.5 kW SynRM. Based on the magnetomotive force (MMF)-permeance method, incorporating the special rotor structure and the characteristics of current harmonics under square-wave drive, an air-gap flux distribution function is established. Meanwhile, Maxwell's stress tensor method is adopted to analyze how the air-gap flux density relates to electromagnetic excitation force waves. Subsequently, this analysis is applied to forecast the spatiotemporal distribution features of radial electromagnetic force waves. Finite element simulations are conducted to compute the modal and vibration responses of the SynRM, followed by a comparative analysis of the vibration characteristics under the two drive methods. Additionally, a 6-pole, 36-slot SynRM is used for additional comparative verification. Ultimately, the effectiveness of the simulation results is verified through experiments.

As industrial technology continues to evolve, synchronous machines powered by inverters are widely implemented to provide enhanced control performance. However, the inverter-fed systems can lead to asymmetries in the three-phase voltages, generating common-mode voltage (CMV) in machines with Y-winding connections configuration. Influenced by the parasitic capacitive effects between the internal conductors of the machine, the CMV results in a potential difference between the shaft and the housing, known as the common-mode shaft voltage (CMSV). When the CMSV exceeds a certain threshold, it can cause the lubricating film of the bearings to break down. To mitigate the risk of bearing failure due to the CMSV, this paper proposes a method for extending stator length, with the advantages of simpler and more cost-effective. This paper first presents the mechanism and mathematical model of CMSV generation, followed by an analysis of potential suppression measures. Furthermore, a method of extending the stator lamination length to reduce the coupling capacitance between the stator windings and the rotor is proposed, thereby achieving suppression of shaft voltage. Finally, a three-dimensional finite element analysis (3D-FEA) software is used to analyze and evaluate the model with different degrees of extending the axial length of the stator or rotor lamination and the machine with different stator inner diameter to axial length ratios. The longer the extension of the stator lamination length, the greater the suppression capability for CMSV. For machines with a larger stator inner diameter to axial length ratio, this method exhibits a more pronounced effect on attenuating the CMSV. Conversely, extending the axial length of the rotor significantly increases the CMSV.

A two-dimensional semi-analytical thermal model (SATM) is presented, aiming to quickly and accurately achieve global temperature distribution predicting and hot spot monitoring for interior permanent magnet synchronous motor (IPMSM). Thereby, it provides a reliable analysis tool for thermal behavior evaluation and prevents undesired consequences induced by excessive temperature rise, which is of great worth and significance in promoting the flourishing of IPMSM. SATM combines the analytical method, lumped parameter thermal network, and finite element analysis to obtain an analytical solution for thermal behavior through mathematical derivation by considering the complicated configuration, heat source distribution, heat dissipation condition, and material thermal dependence. Through SATM, it is possible to observe the global temperature distribution as well as the location and size of hot spots in each element. The temperature distribution gradient on the static is more pronounced than that on the dynamic; secondly, the area with the most severe heating is mainly found on the winding; furthermore, the hot spot on the winding is mainly located a little bit inside the center. Moreover, the thermal behavior of IPMSM at rated load is investigated by numerical analysis and experiments. A comprehensive comparison with SATM is done. The computational deviations between SATM and numerical analysis regarding the hot spot, minimum, and average temperatures on each element are all within 4.06%. However, SATM consumes only 20.92% of the time and 68.29% of the storage of the numerical analysis. The measured data also fully prove the reliability and validity of the comparison. It is certain that SATM can well break through the limitation of the existing non-numerical technique to quickly and accurately achieve global temperature distribution predicting and hot spot monitoring of IPMSM. It provides researchers and engineers engaged in thermal behavior evaluation with good analysis means, design guidance, and optimization direction.

Along with the high-quality development of permanent magnet synchronous motors (PMSMs), the problem of temperature rise has become increasingly prominent. To this end, a semi-analytic model (SAM) combining with the analytical method (AM), the lumped parameter thermal network method (LPTNM), and the finite-element method (FEM) is proposed with the commonly eccentric surface-mounted PMSM (SPMSM) as the main object of study. The complex structure and the varying heat dissipation characteristics of the eccentric SPMSM are reasonably accounted for. Global temperature distribution prediction and hotspot tracking (especially for critical parts, such as eccentric permanent magnets (PMs) and windings) are realized. Meanwhile, the proposed SAM combines high analytical accuracy and fast analytical speed without consuming too much computational resources. Furthermore, the extensibility and the flexible application of the proposed SAM for the multiphysics multiobjective optimization design of the eccentric SPMSM are also investigated. An optimization model is constructed by combining the proposed SAM, machine learning technique, and nondominated sorting genetic algorithm III (NSGA-III). The multiphysics characteristics of the eccentric SPMSM are well improved. Electromagnetic performance is effectively improved, and temperature rise is significantly suppressed. Finally, this study is fully and robustly validated by simulation analysis and prototype experiment. Overall, the proposed SAM has an extremely positive performance. The global temperature distribution predicted by the SAM agrees well with the simulation results. Moreover, the prediction deviations of the hotspot of critical parts are very small, basically within 5.00%, and the ones of the PMs and windings are even lower than 3.50%. Furthermore, the optimization model developed based on the proposed SAM also has excellent optimization performance. The average torque (0.27%) is enhanced, while the torque ripple (74.07%), total loss (9.42%), hotspot of PMs (12.67%), and hotspot of windings (9.92%) are significantly suppressed.

In this article, a three-dimensional hybrid thermal model (3D HTM) applied to the surface-mounted permanent magnet synchronous motor (SPMSM) is first presented. Starting from the x - y plane and the cross section along the z -axis direction of SPMSM, the thermal domain is subdivided, the general solution is derived, and the boundary condition is established. Next, the lumped parameter thermal network and the electromagnetic analytical model (EAM) based on the subdomain method are introduced to solve 3D HTM. The complex structure and heat exchange behavior of SPMSM in 3D space are fully accounted for. Meanwhile, the fast and precise prediction of the global temperature distribution of SPMSM is realized. Subsequently, in view of the excellent performance of 3D HTM, a multiphysics multiobjective optimization model applied to SPMSM is developed by combining EAM and the nondominated sorting genetic algorithm III (NSGA-III). The optimal design of SPMSM is accomplished quickly and efficiently. The multiphysics performance of SPMSM is significantly improved. Finally, the validity, accuracy, and practicality of this study are strongly demonstrated by the simulation computation and prototype experiment.

针对纵向加肋圆柱壳自由振动问题,考虑结构边界条件的复杂性和纵肋截面的任意性,在壳体两端引入连续可变的弹性约束,推导任意截面纵肋剪切中心与圆柱壳中面位移协调关系,并利用Gram?Schmidt正交法构造的级数表示壳体轴向振型函数.采用Novozhilov壳体理论,计及壳体和纵肋能量泛函中各向平移与转动惯性项贡献,基于Rayleigh?Ritz法得到结构自由振动的特征方程表达式,建立纵向加肋圆柱壳自由振动的统一动力学分析模型.调整约束弹簧刚度等效不同边界条件,应用该模型探究了相应边界下肋条附加位置、肋条数量和肋条偏心距对纵向加肋圆柱壳固有频率的影响.研究表明:在一定周向波数范围内,外部加肋和内部加肋圆柱壳固有频率之差的绝对值与周向波数n的变化呈正相关;增加肋条数量会降低内部加肋圆柱壳的固有频率;增大肋条偏心距会降低内部加肋圆柱壳固有频率,且偏心距与肋条数量对固有频率的影响会产生叠加效应.研究结果与验证了所提的统一动力学分析模型的精确性和有效性.

This paper presents a general method for the studies of the vibration characteristics of an electrical machine stator with encased construction under practical boundary conditions. In this paper, artificial springs are introduced at both ends of the stator, and arbitrary boundary conditions can be simulated by adjusting the spring stiffness, including the support conditions in practical applications of the stator. In order to cooperate with the solution of the vibration characteristics of the stator with arbitrary edges, the Gram-Schmidt method is employed to construct characteristic orthogonal polynomial series to simulate the mode shape functions under arbitrary boundary conditions. The analysis is based on the Novozhilov shell theory, which is more applicable to the construction and actual operating environment of stators of electric vehicle drive motors, and takes into account moment of inertia neglected in the past. Further, the effects of teeth, windings, frame and cooling ribs are incorporated in the analysis, and the teeth with complicated shapes are considered as longitudinal ribs of unlimited cross-section, with bending and torsional coupling motion and warping deformation considered. The Rayleigh-Ritz method is used to build a unified dynamic analysis model of the stator of an electric machine, which can provide information on the radial, circumferential and axial vibrations of the stator with higher time efficiency, and a series of comparison studies and experiments are performed to demonstrate the general validity and accuracy of the model. On this basis, the possibility of construction optimization of the stator is discussed to improve the vibration and noise performance while reducing the cost.

The intrinsic shaft voltage caused by the disequilibrium of magnet circuit in permanent magnet synchronous motors(PMSMs) will damage the bearing seriously. In order to suppress the intrinsic shaft voltage preferably, it is necessary to analyze the characteristics of intrinsic shaft voltage qualitatively. Following the magnetic-circuit method and Faraday's law of electromagnetic induction, an analytical model of intrinsic shaft voltage has been proposed. The analytical model can clearly show the harmonic components of intrinsic shaft voltage and the relationship between intrinsic shaft voltage and electromagnetic parameters, which is an important precondition for suppressing intrinsic shaft voltage. Considering the influence of segmented skewed poles, the analytical mode can calculate the optimal number of segmented slices and skew angle, which can successfully avoid intrinsic shaft voltage. In order to testifies the efficacy of the analytical model, the amplitudes and harmonic frequencies are calculate by finite element method (FEM). The results received by the analytical model agree well with the FEM result, which proves the precision of the analytical model.

对于变频器驱动的内置式永磁同步电机,大多数研究集中于变频器共模电压对轴承电压的影响,忽略了磁路不平衡导致的轴电压.针对内置式永磁同步电机动态偏心故障下的轴电压,首先,运用解析法推导轴电压的表达式,分析轴电压的特征频率;其次,研究改变转子磁极的极弧系数削弱偏心轴电压的方法;最后,建立4极6槽、2极9槽、4极9槽、8极9槽在内的4台内置式永磁同步电机偏心轴电压模型,进行有限元验证.仿真结果表明,通过削弱固有轴电压分量可以削弱偏心轴电压,40％偏心度下4台电机削弱效果分别为59.05％、26.90％、43.31％、22.60％.

This paper pays attention to a method to calculate the optimal skewed slots angles which can effectively reduce the intrinsic shaft voltage of permanent magnet synchronous motors(PMSMs). First, the analytical method designed the analytical model which focuses on the qualitative analysis of intrinsic shaft voltage with skewed slots. The analytical model can clearly calculate the optimal skewed slots angle which can reduce the shaft voltage to minimum. The finite element method is used to calculate the shaft voltage of 6-pole/9-slot PMSM and verify that skewed slots is an effective method to reduce intrinsic shaft voltage.

The variable-speed permanent magnet synchronous motors (PMSMs) have high harmonic contents in the current and wide variable speed range, which results in a wide frequency range of electromagnetic force waves and their frequencies change with the speed. Accurate calculation of the natural frequencies of the stator is an important premise for improving electromagnetic vibration and noise. In order to improve the calculation accuracy of the natural frequencies of the stator, the influences of the tooth feet and tooth shoulders are fully considered, the stator core and enclosure are regarded as cylindrical shells with axial ribs attached inside and outside the shells, respectively. Considering the moment of inertia and the transverse shear deformation of the cylindrical shells, the vibration displacement of the continuous system is dispersed by Galerkin dispersion and Rayleigh-Ritz method, the characteristic equations of the stator under free vibration are derived based on the three-dimensional shell theory, and the natural frequencies of the stator with anisotropic material are obtained. In addition, the calculation method of stator natural frequencies under different boundary conditions is given. Further, the natural frequencies of the end cover and the entire motor are analyzed. In order to verify the accuracy of the calculation method, the natural frequencies of a stator are calculated by the finite element method (FEM) and the hammering method. The results obtained by the calculation method in this paper are in good agreement with the experimental results, which proves the effectiveness of the calculation method.

文章介绍了依托国家重点研发计划政府间合作项目"提高中载及重载卡车能效关键技术中美联合研究":(2017YFE0102800)开展的混合动力传动系统动态协调控制技术研究与开发课题,国绕中载及重载卡车混合动力系统模式切换及辅助换挡机理,重点分析混合动力系统模式切换和换挡过程机电耦合机理、多模式动态切换协调控制技术、混动系统换挡电机主动调速控制算法,还介绍了协调控制器硬件电路、控制算法软件、硬件在环测试等.该研究成果具有重要的科学及实用价值,在新能源汽车领域有广阔的应用前景.