Surface Permanent Magnet Synchronous Motor Research Articles

Comparison between a surface permanent magnet synchronous motor and a segmented stator switched reluctance motor with aluminum windings for light electric traction

Nowadays, light electric vehicles are usually powered by drives with motors that use rare-earth permanent magnets. Nevertheless, due to the problems these materials present, light electric vehicle manufacturers are open to considering other alternative drives free of permanent magnets. This paper raises a comprehensive comparison between a surface permanent magnet synchronous motor and a segmented stator switched reluctance motor with aluminum windings for light electric traction, specifically for a motorcycle similar to the Super Soco TCmax.

Influence of Manufacturing Tolerance in Ring Magnet on Cogging Torque of Surface Permanent Magnet Synchronous Machine

Influence of Manufacturing Tolerance in Ring Magnet on Cogging Torque of Surface Permanent Magnet Synchronous Machine

A High-Precision Position Estimation Method for Low Saliency Ratio Machine Based on Convolutional Neural Networks

Sensorless control of surface permanent magnet synchronous motor (SPMSM) faces great challenges in achieving high precision of rotor position estimation at low speed because the saliency of an SPMSM is only a minor secondary effect. In order to extract accurate position information for SPMSM with low and ultra-low saliency ratios, this paper presents a method that implements image recognition techniques with high-frequency (HF) rotating voltage vector injection. For building an image of the induced current vector, the information of the negative-sequence and the second harmonic of positive-sequence HF current signals in the stationary reference frame is extracted. Then, convolutional neural networks (CNN) are applied to the current vector images to establish the relationship between the vector image and the rotor position. Subsequently, the rotor position can be obtained from the result of image recognition from the neural network. Benefiting from CNN’s excellent performance in image classification, the proposed method is able to recognize subtle position signatures even under low saliency. This confirms the opportunity to increase position estimation accuracy for sensorless control of SPMSM. Finally, the experimental results have provided proof that the proposed method has significantly enhanced estimation accuracy.

An Improved Rotor Position Estimation Method for SPMSM With Misaligned Hall-Effect Sensor

This paper presents an improved rotor position estimation method for surface permanent magnet synchronous motor (SPMSM) using a low-resolution Hall-Effect sensor. Firstly, an observation function is proposed to detect the speed variation, and a novel correction method based on optimization process is proposed to identify and correct the deviation angle caused by sensor misalignment. Then, an improved position observer is introduced using a gain-scheduling controller to achieve better performance in both steady state and transient state. The proposed method enhances the anti-perturbation and start-up capability for SPMSM and compensate the misalignment effect of Hall-Effect sensors. Experimental results are demonstrated to verify the effectiveness of the proposed method.

Structural effects of asymmetric magnet shape on performance of surface permanent magnet synchronous motors

This study proposes a novel surface permanent magnet synchronous motor (N-SPMSM) structure, which features asymmetric magnets attached to the rotor surface. The N-SPMSM structure exhibits reduced structural complexity and minimal electromagnetic performance degradation. The properties of N-SPMSM are analyzed by comparing its structural complexity (in terms of the shape) and manufacturing complexity and electromagnetic performance [in terms of the cogging–mutual torque ratio and back-electromotive force (EMF) values], with the corresponding values of a ring-type SPMSM (R-SPMSM) and step-skew-type SPMSM (T-SPMSM). The analysis results demonstrate that N-SPMSM has lower shape complexity than T-SPMSM and lower manufacturing complexity than both R-SPMSM and T-SPMSM. The cogging torque reduction and back-EMF performances of N-SPMSM are similar to that of R-SPMSM and T-SPMSM.

Spatial-Harmonic Modeling and Analysis of High-Frequency Electromagnetic Vibrations of Multiphase Surface Permanent-Magnet Motors

This article introduces a spatial-harmonic model for analyzing high-frequency vibrations induced by PWM-current harmonics in inverter-fed surface permanent magnet synchronous motors (PMSMs). The model provides a fresh perspective on calculating high-frequency vibrations of motors with a fixed inverter switching frequency. Electromagnetic (EM) forces along stator boundaries are first calculated utilizing the permeance distribution function (PDF). Then, the concept of spatial-order-excitation transfer functions (SOETFs) is introduced to facilitate the modelling of the motor vibrational response under distributed excitation forces. Two approaches to obtain SOETFs are subsequently investigated, one by finite-element analysis while the other by experimental identification. Finally, high-frequency vibrations predicted by the proposed model are validated by experiments, showing a high degree of accuracy.

Analytical Approach for Estimating the Average Torque of Synchronous Motors by Using the Flux Density in the Air Gap

In this study, a generalized torque estimation method is proposed for synchronous motors, including surface permanent magnet synchronous motors (SPMSMs), synchronous reluctance motors (SynRMs), and interior permanent magnet synchronous motors (IPMSMs) for building the analytical motor model. The average motor torque is estimated using the Lorentz force by the generated flux density in the air gap to determine the relationships among torque, flux density, and injected current. In the proposed method, the generated flux density is derived step by step by considering the effects of magnetic flux saturation, the stator slot, the rotor barrier, and permanent magnets (PMs) to ensure that the generated average torque complies with the operating condition of the motor. To verify the proposed method, the output torque of finite element analysis (FEA), Maxwell 2D, is compared to the proposed method in a SPMSM. Moreover, a phasor diagram is plotted to determine the mechanism through which torque is generated in SynRMs and IPMSMs. A SynRM and an IPMSM with ferrites PMs are analyzed using the proposed method, FEA, and the experimental results of this study indicate the effectiveness.

Investigation of Interior Permanent Magnet Synchronous (IPMS) Machine Applications in Electrical Vehicle Engine Industry

This paper discusses the selection of an interior permanent magnet synchronous machine and converter for a 100V-200V DC, 100-400 Hz, 150-175 Nm, 30kW-100kW, 1550-4100 rpm electrical vehicle engine alternator. The electrical vehicle engine application requirements are outlined including the engine coupling configuration. Then the characteristics of different machines and their converters are compared through a competitive trade-off study framed by the alternator requirements; direct-drive induction, variable-reluctance, surface permanent magnet synchronous machine, and interior permanent magnet synchronous machine are all considered. The results of the study indicate that the interior permanent magnet synchronous machine is a potentially superior candidate, and so this machine is selected for further investigation. The preliminary findings are described, and the paper concludes with a discussion of current work addressing analytic design.

Active Fault-tolerant Control for Surface Permanent Magnet Synchronous Motor Under Demagnetization Fault

This paper introduces a novel method for controlling a surface permanent magnet synchronous motor (SPMSM) during demagnetization fault conditions. The proposed fault-tolerant control (FTC) system incorporates a combination of a fuzzy extended state observer (FESO) based on an interval type 2 fuzzy logic controller (IT2FLC) and second-order sliding mode control (SOSMC) utilizing the super-twisting algorithm. The FESO aims to identify and eliminate demagnetization faults through reconstruction control. The FTC system enhances the dynamic performance and disturbance rejection of the SPMSM, providing a robust solution in the event of a demagnetization fault.

Estimation of Electrical Angular Position and Load Torque for Sensorless Control Design in Permanent Magnet Synchronous Motor

This work proposes the design of an extended state observer to estimate the electrical angular position, angular velocity, and load torque of a surface permanent magnet synchronous motor. We propose a rotating mathematical model (d,q) modified to the observer design when exists an alignment error between the actual and estimated reference frame. From the study of the observer's stability, we propose a methodology to estimate the electrical angular position of the rotor. Finally, we perform high-precision emulations to validate the theoretical results.

Cold-Spray Additive Manufacturing of a Petal-Shaped Surface Permanent Magnet Traction Motor

Several applications require low torque pulsations as they can lead to mechanical vibrations and acoustic noise in the electric motor. Optimization of the rotor permanent magnet (PM) shape is one of the effective methods for reducing torque pulsations. Unfortunately, the low versatility of the magnet fabrication technologies limits the development of new motor geometries. Cold spray additive manufacturing can be used for shaping permanent magnets for the direct fabrication of motor parts without the need for additional assembly steps. This fabrication technique allows an increase in the design flexibility of electric machine geometries targeting improved performance. This paper investigates the performance of permanent magnet rotors fabricated using a cold spray additive manufacturing technique for radial flux surface permanent magnet synchronous machines (SPMSM). The permanent magnet rotors considered are conventional rectangular-shaped with unskewed magnets (Model A), skewed magnets (Model B), and sinusoidal-petal shaped magnets (Model C) along the axial direction. The magnitude of magnetization current pulse required to magnetize these rotors is calculated and an impulse magnetizer setup is designed for in-situ magnetization. The performance of the shaped cold sprayed permanent magnet rotors and their effects on back EMF, electromagnetic torque, and cogging torque are analyzed experimentally and comparisons are made between the different rotor designs.

Sensorless model predictive control based on I‐f integrated sliding mode observer for surface permanent magnet synchronous motor

SummaryDue to the limited fast dynamic response of the dual proportional‐integral (PI) control strategy in sensorless speed control, a novel composite control strategy is proposed for sensorless control of the full speed range of the surface‐mounted permanent magnet synchronous motor. This strategy combines dual closed‐loop model predictive control (MPC) with a sliding mode observer (SMO) and a constant current‐frequency ratio (I‐f). The I‐f control scheme is employed in the low‐speed range, while the SMO is utilized for motor speed and rotor position estimation in the medium and high‐speed ranges, enabling the dual‐loop MPC. Furthermore, a new smooth switching method is proposed for transitioning between the two control methods. In addition, the MPC outer loop parameters were thoroughly analyzed and optimized for better dynamic performance of sensorless control. The steady‐state performance of this control strategy is compared to PI control and improved the dynamic responsiveness of the system. Experiments have verified the feasibility of this strategy. Under the control of the MPC outer loop, the steady‐state speed fluctuation of the motor is within 10 r/min. Compared to PI control, the motor settling time was reduced by 17% and 60% during the start‐up phase and after a sudden speed change, respectively.

Predictive Position Control With System Constraints for PMSM Drives Based on Geometric Optimization

The system constraints (current, speed and voltage limitations) are essential for the safety control of predictive position control (PPC) method. However, online solution of model predictive control (MPC) with complex system constraints is still a challenge. In this paper, a novel discrete-time model predictive position control (DMPPC) strategy for surface permanent magnet synchronous motor (SPMSM) drive is proposed, the current, speed and position are regulated simultaneously. The optimization model of the position control system considering system constraints is formulated, the current, speed and voltage constraints are analyzed and transformed into the incremental voltage constraints. To reduce the calculation burden, a simplified method based on the geometric boundaries and cost function is proposed to solve the optimization problem, complex iterative calculations are avoided, the system constraints are well limited and less calculation time can be achieved. Finally, the proposed DMPPC method is experimentally verified and compared with a traditional iterative method and a cascade predictive position control (CPPC) method.

Electromagnetic Characteristics of Dual-Air-Gap Surface Permanent Magnet Synchronous Motor

This paper introduces a novel dual-air-gap surface permanent magnet synchronous motor (DAG-SPMSM) and investigates its electromagnetic characteristics. The motor comprises two stators (inner and outer) and a single rotor with permanent magnets on both sides (inner and outer). The magnets are arranged in a zig-zag configuration to isolate the inner and outer stator and rotor magnets. Additionally, a magnetic shield is incorporated into the rotor to further isolate the rotor magnetic flux, which results in a localized short flux path that can reduce core loss. The insertion of the magnetic shield also affects the flux path, reducing torque ripple. The electromagnetic characteristics, such as flux path, flux density, and torque, are analyzed using finite element analysis. The effectiveness of using a magnetic screen is also evaluated, and simple experiments are conducted to validate the observed characteristics of the proposed motor.

Surface Permanent Magnet Synchronous Machines: High Speed Design and Limits

Surface permanent magnet synchronous machines are one of the most widely adopted machine topologies in high-speed applications where efficiency and power factor cannot be compromised. Although the design of such machine type has been extensively investigated in both industry and academia, this work aims at addressing its limitations when applied in high-speed applications. First, this paper proposes an accurate design methodology for continuous-duty high-speed surface-mounted permanent magnets synchronous machines, capable of accounting for the rise of the speed-dependent losses and structural needs with a limited impact on the computational burden. The outlined approach can be used to speed-up the initial design stage as it allows to reduce the number of solutions to evaluate before commencing the refinement stages required before the definition of the final design. Indeed, the introduced design approach is used to systematically assess the maximum power capability as function of the maximum speed and the airgap thickness for a given outer envelope and cooling system. The influence of the high-speed limiting factors is deeply investigated also considering their effects on the machine geometries providing the highest torque. The selection of the final design is discussed and justified. Experimental results of the 4.2kW-80kprm prototype validate the design methodology.

Parameter Robust Deadbeat Predictive Current Control for Open-Winding Surface Permanent Magnet Synchronous Motor Drives

Deadbeat predictive current control (DPCC) of open-winding surface permanent magnet synchronous motor (OW-SPMSM) has excellent dynamic and steady-state performance, but it depends heavily on the accuracy of motor model parameters (resistance, inductance, and flux linkage). To eliminate the influence of parameter mismatch and retain the fast dynamic performance of the traditional DPCC, a parameter robust DPCC for OW-SPMSM drives is proposed in this paper. Firstly, the incremental prediction model of OW-SPMSM is introduced which eliminates the flux linkage parameters in traditional DPCC. Secondly, the parameter sensitivity analysis shows that the mismatch of resistance parameter hardly affects the current prediction errors of incremental prediction model, which are mainly caused by the mismatch of inductance parameters. Finally, to extract the actual inductance information, an inductance extraction strategy is proposed. Experimental results show that the current control performance of the proposed robust DPCC is not influenced by any motor parameter mismatch, which always has smaller current tracking errors and total harmonic distortion (THD) than traditional DPCC. Moreover, compared with the existing robust DPCC with observers, the proposed DPCC has better dynamic response performance.

A Simplified Virtual-Vector-Based Model Predictive Control Technique With a Control Factor for Three-Phase SPMSM Drives

Compared with the single vector-based model predictive control (MPC) technique, the multiple vector-based MPC technique gains interests in improving the total harmonic distortion (THD) of the stator currents and reducing electromagnetic torque and stator flux ripples for a three-phase surface permanent magnet synchronous motor (SPMSM). However, the complicated enumeration and operation in vector selection and duty cycle calculation increase the computational burden and limit its peneration. Hence, in this paper, a simplified virtual vector-based MPC with a control factor for a three-phase SPMSM is proposed. Without sector identification and enumeration operations, the proposed technique utilizes the control factor to automatically generate a large number of virtual vectors to achieve equivalent performance effectiveness with multiple vector-based MPC technique with lower sampling frequency. Subsequently, regardless of the number of virtual vectors, the candidate virtual vectors are directly identified in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$x-y$</tex-math></inline-formula> coordinate system to greatly reduce the computational burden. In addition, the duration of the selected optimal virtual vector and the resultant switching sequences are easily obtained and arranged to even the switching losses among the switching devices and further optimize the THD of the stator current. The proposed technique is simplified and flexible. Its control effectiveness is verified by experimental results.

Effective Position Error Compensation in Sensorless Control Based on Unified Model of SPMSM and IPMSM

Sliding mode observer (SMO) has attracted extensive attention in the field of medium- and high-speed sensorless control of permanent magnet synchronous (PMSM) because of its strong robustness and stability. However, the traditional methods are vulnerable to dc bias caused by measurement errors and parameter changes. Therefore, an improved SMO algorithm by disturbance observer compensation is proposed in this article. The algorithm unifies the mathematical models of surface PMSM and interior PMSM. Besides, a band-pass filter (BPF) is used to replace the traditional low-pass filter, so it can effectively suppress dc bias and high-frequency noise. In addition, at any BPF center frequency, the proposed disturbance observer with LPF characteristics can perfectly compensate the position error caused by the digital filter in real time. Moreover, through sensitivity analysis, the influence of model uncertainty on the observation position is studied, and an adaptive extended state observer is added to mitigate the influence of parameter mismatch on the performance, and hence improving the estimation accuracy. Finally, a triple redundant permanent magnet assisted synchronous reluctance motor is taken as an example to verify the feasibility and effectiveness of the proposed observer.

A Novel Duty-Controlled DTC of a Surface PMSM Drive With Reduced Torque and Flux Ripples

Direct torque control (DTC) is a widely used method for the control of permanent magnet synchronous motor (PMSM) drive. DTC suffers the drawback of high ripples in torque and flux. Various duty-cycle-controlled DTC methods have been introduced in the recent past to improve the steady-state response of the PMSM. However, the existing duty-cycle-controlled DTC methods are complex and result in higher switching frequencies. This article introduces a novel duty-controlled DTC for reducing the ripple in torque and flux without giving considerable rise in the switching frequency and computation burden. The proposed DTC applies two separate voltage vectors (VVs) for individual control of stator flux and torque during two different sampling intervals. A look-up table is proposed to select candidate VVs and their duty ratios are calculated to achieve the reference values of stator flux and torque in two sampling intervals. This causes a major reduction in the torque and stator-flux ripples. Also, the proposed method decides the sequence of candidate VVs to reduce the number of switching and thereby reduce the switching frequency. The proposed method is experimentally tested and compared with conventional DTC, an existing duty-based DTC, and deadbeat DTC to verify its effectiveness.

Multi-objective optimization of the hollow shaft direct drive motor

Surface permanent magnet synchronous motor (SPMSM) is widely used in low-speed and high torque permanent magnet synchronous motor. A multi-objective optimization method of hollow shaft direct drive motor (HSDDM) for double direct drive feed system (DDFS) is proposed in this paper. Several dimensions of HSDDM are considered in the proposed design procedure including pole embrace, thickness of magnet, eccentric distance, and air gap length. A multi-objective optimization model is established to minimize cogging torque, maximize efficiency, and minimize the magnet weight. The Optimized Latin hypercube sampling (OLHS) is used to design the experimental samples, and the sampling results are calculated by the finite element method (FEM). The Kring approximate model is established according to the sampling results. Based on the established approximate model, NSGA II multi-objective genetic algorithm is used to optimize the HSDDM. Compared with that before optimization, the efficiency after optimization is increased by 4.08%, the cogging torque is reduced by 86.78%, and the magnet weight is reduced by 20.24%. Eventually, the integration of NSGA-II and FEM provides an effective approach to obtain the optimal design of HSDDM.