Calculation Model of Armature Reaction Magnetic Field of Interior Permanent Magnet Synchronous Motor with Segmented Skewed Poles

In an interior permanent magnet synchronous motor (IPMSM) with segmented skewed poles, the armature reaction magnetic field (AR-MF) changes nonlinearly due to the saturation of the rotor magnetic barrier. Meanwhile, this varies under different excitation currents. As a result, it is difficult to be calculated by means of analytical methods. In this paper, the calculation model of AR-MF of IPMSM is first established by vector superposition method, without considering the saturation effect of rotor and the slotting effect of stator. In the second step, the virtual magnetic field of the rotor is introduced to quantitatively calculate the influence of local inhomogeneous saturation on the AR-MF. The latter is derived by combining both the subdomain method and equivalent magnetic circuit method. The complex relative permeance is also introduced to establish the AR-MF accounting for the stator slotting effect. To validate the AR-MF calculation method proposed, an 8-pole 48-slot IPMSM with segmented skewed poles is considered as a case study, showing a comparison by both with finite element (FE) results and the electromagnetic torque measured on a test bench. The model proposed in this paper shows high accuracy and fast computation with respect to FE analysis

Calculation Model of Armature Reaction Magnetic Field of Interior Permanent Magnet Synchronous Motor with Segmented Skewed Poles

In an interior permanent magnet synchronous motor (IPMSM) with segmented skewed poles, the armature reaction magnetic field (AR-MF) changes nonlinearly due to the saturation of the rotor magnetic barrier. Meanwhile, this varies under different excitation currents. As a result, it is difficult to be calculated by means of analytical methods. In this paper, the calculation model of AR-MF of IPMSM is first established by vector superposition method, without considering the saturation effect of rotor and the slotting effect of stator. In the second step, the virtual magnetic field of the rotor is introduced to quantitatively calculate the influence of local inhomogeneous saturation on the AR-MF. The latter is derived by combining both the subdomain method and equivalent magnetic circuit method. The complex relative permeance is also introduced to establish the AR-MF accounting for the stator slotting effect. To validate the AR-MF calculation method proposed, an 8-pole 48-slot IPMSM with segmented skewed poles is considered as a case study, showing a comparison by both with finite element (FE) results and the electromagnetic torque measured on a test bench. The model proposed in this paper shows high accuracy and fast computation with respect to FE analysis

Analysis of longitudinal-vertical coupling vibration of four hub motors driven electric vehicle under unsteady condition

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfc and inverter switching frequency sideband harmonic k1fs±k2fc (fc = pn/60, fs is inverter switching frequency, k1 and k2 are positive integers, p is the number of pole pairs and n is motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3fc and 2fs. The main harmonic of vehicle body pitch angle acceleration is 2fs.</p

Prediction and Diagnosis for Unsteady Electromagnetic Vibroacoustic of IPMSMs for Electric Vehicles Considering Rotor Step Skewing and Current Harmonics

Purpose: This study provides a detailed investigation on the prediction and diagnosis of unsteady electromagnetic vibroacoustic performance of IPMSMs for electric vehicles under typical unsteady operating conditions with consideration of rotor step skewing and current harmonics. Methods: Firstly, the control model considering the influence of PWM carrier modulation and rotor step skewing is established. Based on this, the currents of the IPMSM under unsteady operating conditions (driving condition and feedback braking condition) are obtained. Accordingly, the currents calculated through the control model are used as the excitation source of electromagnetic finite element. Then, the electromagnetic vibroacoustic performance under unsteady operating conditions is calculated through electromagnetic force subsection mapping and acoustic transfer vector (ATV) method. Moreover, the conditions where resonance vibroacoustic occurs are diagnosed. Finally, the results of prediction and diagnosis are fully verified by experiments of multiple physical fields. Results and Conclusions: The amplitude errors between prediction results and test results are less than 3.2%. The influence of current harmonics on electromagnetic vibroacoustic can be predicted. The frequency range and speed range of predicted peak vibroacoustic are consistent with the experimental results. The rotor step skewing can be used to weaken the vibroacoustic amplitude of IPMSMs under typical unsteady conditions in the full speed range. This study provides guidance for prediction and diagnosis for electromagnetic vibroacoustic performance of IPMSMs under typical unsteady operating conditions.</p

Prediction and Diagnosis for Unsteady Electromagnetic Vibroacoustic of IPMSMs for Electric Vehicles Considering Rotor Step Skewing and Current Harmonics

Purpose: This study provides a detailed investigation on the prediction and diagnosis of unsteady electromagnetic vibroacoustic performance of IPMSMs for electric vehicles under typical unsteady operating conditions with consideration of rotor step skewing and current harmonics. Methods: Firstly, the control model considering the influence of PWM carrier modulation and rotor step skewing is established. Based on this, the currents of the IPMSM under unsteady operating conditions (driving condition and feedback braking condition) are obtained. Accordingly, the currents calculated through the control model are used as the excitation source of electromagnetic finite element. Then, the electromagnetic vibroacoustic performance under unsteady operating conditions is calculated through electromagnetic force subsection mapping and acoustic transfer vector (ATV) method. Moreover, the conditions where resonance vibroacoustic occurs are diagnosed. Finally, the results of prediction and diagnosis are fully verified by experiments of multiple physical fields. Results and Conclusions: The amplitude errors between prediction results and test results are less than 3.2%. The influence of current harmonics on electromagnetic vibroacoustic can be predicted. The frequency range and speed range of predicted peak vibroacoustic are consistent with the experimental results. The rotor step skewing can be used to weaken the vibroacoustic amplitude of IPMSMs under typical unsteady conditions in the full speed range. This study provides guidance for prediction and diagnosis for electromagnetic vibroacoustic performance of IPMSMs under typical unsteady operating conditions.</p

Analysis of longitudinal-vertical coupling vibration of four hub motors driven electric vehicle under unsteady condition

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfc and inverter switching frequency sideband harmonic k1fs±k2fc (fc = pn/60, fs is inverter switching frequency, k1 and k2 are positive integers, p is the number of pole pairs and n is motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3fc and 2fs. The main harmonic of vehicle body pitch angle acceleration is 2fs.</p

Open-Circuit Air-Gap Magnetic Field Calculation of Interior Permanent Magnet Synchronous Motor With V-Shaped Segmented Skewed Poles Using Hybrid Analytical Method

Due to the local inhomogeneous magnetic saturation of the core of the interior permanent magnet synchronous motor (IPMSM), the magnetic field changes nonlinearly, which makes the analytical calculation of the magnetic field difficult. Therefore, the calculation of the magnetic field mostly relies on the finite element method (FEM). However, the high computation cost of FEM restricts the efficiency of the design and analysis of IPMSM. In this article, an analytical model (AM) of slotless open-circuit air-gap magnetic field (OC-AG-MF) of IPMSM with V-shaped segmented skewed poles is derived by combining the subdomain method (SDM) and the magnetic equivalent circuit (MEC) method, and then, the AM of slotted OC-AG-MF of IPMSM with V-shaped segmented skewed poles is obtained by introducing the complex relative permeance. To show the effectiveness of the novel AM, the OC-AG-MF and cogging torque of an IPMSM with V-shaped segmented skewed poles for electric vehicles are calculated by the AM and FEM, respectively. The spatial order, amplitude–frequency characteristics, and the 3-D spatial distribution of the OC-AG-MF are analyzed. Finally, the accuracy of the AM is experimentally verified by direct measurement of OC-AG-MF and no-load back electromotive force (EMF) of the motor. The AM proposed in this article is shown to accurately calculate the radial and tangential components of OC-AG-MF of IPMSM with V-shaped segmented skewed poles considering rotor magnetic bridge saturation effect and stator slotting effect. Meanwhile, the efficiency of the design and analysis of the motor is expected to be improved due to the reduced computational effort compared to the prevalent FEM