Surface-mounted Permanent Magnet Synchronous Motor Research Articles

Analysis and Design Methodology of Radial Flux Surface-Mounted Permanent Magnet Synchronous Motors

Permanent magnet motors have become very important in recent years due to the popularization of electric vehicles in the context of the efforts to transition to zero-emission transportation. This has encouraged researchers and hobbyists to learn about electric motor design. However, designing electric motors is not a simple task, as the information to achieve it is not easily available to everyone and it is usually complicated to understand. For that reason, this paper presents the equations and a basic process to design radial flux surface-mounted PM synchronous motors. This design method is the result of combining and organizing information from previous publications to create a relatively simple design guide. The result is a table of equations and a series of general guidelines that were verified by designing and simulating a 500 W eight-pole 2.6 Nm average torque dual-rotor motor and a 20 W four-pole 106 mNm single-rotor motor. The simulations validated the equations and the design method presented in this paper to be used by those interested in the field of electric motors and vehicles; therefore, in the future, others may contribute with improvements, particularizations or optimizations of this methodology, or even create their own.

Robust Constant Exponent Coefficient Fixed-Time Control Based on Finite-Time Extended Sliding Mode Observer of Permanent Magnet Synchronous Motors

This paper presents the Robust Constant Exponent Coefficient Fixed-Time Control (CECFSMC), an innovative control technique for precisely regulating the speed of a permanent magnet synchronous motor (PMSM) by utilizing fixed-time stability with constant exponent coefficients to provide not only faster convergence but also in a specific period of time. The effect of chattering is also lessened. To ensure that the designed controller produces the desired performance under bounded disturbances, a finite-time extended sliding-mode observer (ESMO) is also designed to estimate the PMSM velocity while also estimating lumped load disturbances. The considered PMSM is the surface-mounted PMSM. Finally, a numerical simulation with PMSM drive shows good robustness against load disturbances, better convergence, and a reaching time of less than 2 s, thereby demonstrating that the proposed fixed-time constant exponent coefficient offers good performance and is much simpler than the conventional finite-time method.

Design and Experimental Verification of Hubless Rim-Driven Propulsor Consisting of Bearingless Propeller for an Unmanned Underwater Drone

This paper presents the design and experimental verification of a hubless rim-driven propulsor (HRDP) for an unmanned underwater drone. The bearings of the HRDP are required to rotate and fix the propeller. However, the bearing increases the weight and size of the propulsor. Therefore, this paper proposes a structure in which the rotor of a surface-mounted permanent magnet synchronous motor (SPMSM) and a hubless propeller are combined without the bearings in the rim-driven propulsor. The design procedure of the propulsor is established and the response surface method (RSM) is used to design and optimize the proposed structure. The validity of the HRDP with the proposed structure is verified through simulation results using an electromagnetic field (EF) analysis and computational fluid analysis, and test results using a water tank. Finally, compared to the initial HRDP, the weight of the SPMSM in the optimized HRDP is decreased by 7.3%, and by reducing the required torque by about 19%, power consumption is reduced by about 24.66 W.

Incorporating the coupled effects of slot opening, armature reaction and saturation in the model of the airgap flux density distribution of permanent magnet synchronous machines

AbstractA new analytic model for calculating of the air‐gap flux density (AGFD) of surface‐mounted permanent magnet synchronous machines (SMPMSMs) is presented. This proposed model is capable to taking into account the effects of magnetic saturation, armature reaction and stator slots opening. Furthermore, the real form of air‐gap distribution and spatial distribution of flux density of the PM poles are considered. The armature reaction effect is modeled using phasor diagram analysis of the motor as a function of the load torque, the armature current amplitude, power factor and the inverse air gap length. Also, saturation phenomenon predicted using the new non‐linear proposed function in connection with the armature reaction effects and the properties of the lamination material. It is shown that the proposed model capable to predicting acceptably the air gap flux density waveform of the SMPMSMs at lagging and leading power factors and with the load torque variation. The presented analytical approach is verified by the two‐dimensional finite‐element analysis (FEA) results.

Eccentricity fault detection in surface-mounted permanent magnet synchronous motors by analytical prediction, FEM evaluation, and experimental magnetic sensing of the stray flux density

The paper discusses the impact of rotor eccentricity in permanent magnet synchronous motors (PMSMs), which leads to increased motor vibration and unbalanced magnetic pull, resulting in accelerated aging of motor parts. Undetected eccentricity in the motor can exacerbate these issues and lead to a higher risk of stator-rotor contact and forced outages. The study proposes a technique for detecting eccentricity faults using an analog magnetic field sensor outside the motor, without requiring the sensor to be installed within the motor. The proposed technique was evaluated using analytical calculations, 2-D finite elements, and experimental results. The proposed method was evaluated in different scenarios and it was found to be capable of providing detection and identification of parallel and inclined eccentricity. The size of the magnetic field at a specific point in the outer space of the motor was estimated to be 26μT, 30μT, and 43μT, respectively, through analytical modeling in healthy conditions, 10% and 30% eccentricity, and it was confirmed by experimental testing. Since the proposed method does not require installing sensors or search coils within the motor, such a method is more appropriate for practical applications and improving the cost-performance in online condition monitoring. In addition, with some specific modifications, the suggested concept becomes useful for fault detection in other rotating machinery types.

Deadbeat Predictive Current Control for Surface-Mounted Permanent-Magnet Synchronous Motor Based on Weakened Integral Sliding Mode Compensation

Deadbeat predictive current control (DPCC) has excellent dynamics and can achieve current control with less computational effort. However, its control performance relies on the precision of the parameters of the motor. Current static error will be generated and control performance will be decreased when the predictive model parameters do not correspond to the practical parameters of the motor. In this article, a weakened integral sliding mode compensation method is proposed which converts the current error into a voltage compensation term and adds it to the prediction control output to effectively compensate for the steady-state error. In addition, a boundary layer is introduced to weaken the integral so as to solve the problems of integral saturation and overshoot caused by the introduction of the integral term when the error is large. Moreover, weight factors are introduced to optimize the feedback current, which enhances the robustness of the system. In the end, the effectiveness of this method is verified via simulation and experimental results.

Direct Speed Composite Control of SPMSM Drive System

The surface mounted permanent magnet synchronous motor (SPMSM) is a complex and nonlinear system. Therefore, single control method is difficult to perform well in different operations. For this reason, the direct speed composite control of SPMSM drive system is proposed in this paper. First, the control laws are deduced from the designed sliding mode surface and integral sliding mode surface under non-cascaded structure respectively. On the basis of guaranteeing the system stability, the dynamic weight factor is designed innovatively with speed error to perceive system state and allocate the ratio of two control laws in real time. Accordingly, the proposed composite control can be implemented by dynamic weight factor and make full use of two abovementioned control laws. Furthermore, by establishing ultra-local model of the SPMSM drive system, the nonlinearities, uncertainties and unknown disturbances of the system are estimated together and fed back to the controller, and the system robust improvement can be achieved consequently. At last, system simulation and experimental researches validate that the proposed direct speed composite control realizes smooth transition of two control methods and improves dynamic and steady-state control performance of the system.

Speed Control of PMSM Based on Fuzzy Active Disturbance Rejection Control under Small Disturbances

Permanent Magnet Synchronous Motors (PMSMs), with their simple design, small size, and high-power factor, are ideally suited for realizing high-power AC drives and are widely used in various industries. In this study, Fuzzy Active Disturbance Rejection Control (Fuzzy-ADRC) is used to control the speed of the PMSM. When a slight external disturbance occurs, this control strategy maintains the suppression characteristics of the self-excited control for the disturbance and enhances its ability to compensate for the disturbance. First, a mathematical model was developed to study the surface mount PMSM. Then, a motor control simulation model was created using PI control, vector control, and other control methods. The verification results indicate that the improved Fuzzy-ADRC system performs well under both internal and external minor disturbances. It exhibits a faster dynamic response and reduced regulation time (0.026 s to 0.017 s) compared to the traditional ADRC system. Furthermore, it shows less overshoot (reduced from 70% to 2.9%) compared to the Sliding Mode Observer (SMO). Taken together, the improved Fuzzy-ADRC system is characterized by small steady-state error, high load capacity, and control accuracy. With the assistance of this control strategy, the system can track speed with high accuracy and possesses stronger anti-interference capability to mitigate load disturbances.

Sensorless control of SPMSM based on an adaptive sliding mode observer with optimized phase-locked loop structure

To improve the speed and position detection accuracy of surface-mount permanent magnet synchronous motor (SPMSM) vector control and reduce unnecessary chattering of the system, this paper proposes a sensorless control strategy of SPMSM based on an adaptive sliding mode observer (ASMO) with optimized phase-locked loop (OPLL) structure. First, in order to overcome the chattering of system caused by discontinuous switching characteristic of signum function in conventional sliding mode observer (CSMO), a continuous saturation function is selected as the switching function. The ASMO adopts the system state-related adaptive gain function to adjust the switching gain value of the system in real time, which overcomes the slow response speed or severe chattering of the system caused by the constant switching gain of CSMO. Second, to reduce the phase delay between the rotor position estimation value and the actual value caused by the adoption of low-pass filter (LPF) and the position estimation error caused by arctangent function method, an OPLL method is designed for accurate estimation of rotor position and speed. Finally, the effectiveness and feasibility of the proposed improved SMO algorithm is verified by simulation and experiments on an SPMSM with rated power of 2 kW.

Three-Stage Duty Cycle-Based Deadbeat Predictive Torque Control for Three-Phase SPMSMs With CMV Reduction

Model Predictive Torque Control (MPTC) is highly regarded for its simple structure, rapid dynamic response, and optimized control performance when applied to actual motor driving systems. However, conventional MPTC techniques often lead to undesirable effects in three-phase inverter-based surface-mounted permanent magnet synchronous motors (SPMSMs), such as high electromagnetic torque, stator flux ripples, and significant current harmonic distortion. Notably, the generalized MPTC approach generates a substantial common mode voltage (CMV) that can cause damage to the motor bearing and winding insulation in SPMSMs. To address these issues, this paper proposes a three-stage duty cycle-based deadbeat predictive torque control (DCDPTC) technique for SPMSMs. The proposed technique leverages the volt-second equilibrium theorem by aligning the duty cycles with the predicted electromagnetic torque, stator flux, and their respective target values while accounting for extreme cases, accordingly electromagnetic torque and stator flux ripples as well as the total harmonic distortion (THD) of the stator current are minimized. In order to improve the system robustness, the duty cycle is limited to avoid the overmodulation. Furthermore, optimized switching sequences are meticulously arranged to ensure the CMV is lowered and the minimum number of switching transitions is maintained while utilizing a fixed switching frequency. The proposed technique is simplified. Its resultant performance is validated by experimental results.

Robust Exploration Based Finite Control Set Predictive Current Control for SPMSM Drives Under Influence of Measurement Error

To improve the performance and the robustness of finite control set predictive current control (PCC) under the influence of current measurement error in the actual system, robust exploration based finite control set predictive current control (RE-PCC) is proposed in this paper. Firstly, to analyze directly transient and steady state of system operation, a voltage cost function without weighting factor is designed based on predicted voltage error vector, reference voltage vector and evaluated voltage vector. Secondly, the robust exploration is designed to overcome the influence of measurement error by combing the amplitude and phase attribute between the predicted voltage error vector and the ideal reference voltage vector. Thirdly, based on the robust exploration, the desired sector and the prior vector set is derived for cost function evaluation. It is great benefit to computational burden and switching losses by reducing the seven vectors to three. Finally, the RE-PCC method is experimentally compared with an improved PCC method in terms of robustness, current quality, torque ripple, dynamic characteristics and efficiency. The experimental results verify the high robustness and superior control performance of RE-PCC method in surface-mounted permanent magnet synchronous motor (SPMSM) drives.

Simplified Model Predictive Current Control for Surface- Mounted Permanent-Magnet Synchronous Motor Drives with Adaptive Duty Modulation

Parameter control and cost minimization are among the significant aspects of model predictive current controllers. However, with the conventional control scheme of fixed switching vector actuation, susceptibility to uncontrolled current ripples remains a primary concern. This paper presents a simplified approach of model predictive current controller baed on adaptive duty modulation for the surface-mounted permanent-magnet synchronous motor (SPMSM). In this method, the implementation of two successive synthesized voltage vectors adopts the adpative soft-switching combination in each control period. Experimental results validate performance improvement and optimize current predictive accuracy.

Analysis and Real-Time Calculation of Postfault Current of Standard Surface-Mounted PMSM Drives With Dysfunctional Power Switches

Analysis and Real-Time Calculation of Postfault Current of Standard Surface-Mounted PMSM Drives With Dysfunctional Power Switches

A Mid-fidelity Model in the Loop Feasibility Study for Implementation of Regenerative Antilock Braking System in Electric Vehicles

<div>The tailpipe zero-emission legislation has pushed the automotive industry toward more electrification. Regenerative braking is the capability of electric machines to provide brake torque. So far, the regenerative braking feature is primarily considered due to its effect on energy efficiency. However, using individual e-machines for each wheel makes it possible to apply the antilock braking function due to the fast torque-tracking characteristics of permanent magnet synchronous motors (PMSM). Due to its considerable cost reduction, in this article, a feasibility study is carried out to investigate if the ABS function can be done purely through regenerative braking using a mid-fidelity model-based approach. An uni-tire model of the vehicle with a surface-mount PMSM (SPMSM) model is used to verify the idea. The proposed ABS control system has a hierarchical structure containing a high-level longitudinal slip controller and a low-level SPMSM torque controller. Given the uncertainties of the tire–road dynamics, a sliding mode control method is designed and employed as a high-level slip controller. Also, a PID vector control method is used to keep the SPMSM braking torque at the optimal value requested by the high-level controller. Moreover, in order to estimate the tire longitudinal slip and vehicle velocity, an extended Kalman filter (EKF) is developed that estimates both parameters at the same time. The results show that the proposed hierarchical control and estimators can keep the tire longitudinal slip at the optimal value and prevent the wheel from locking in a variety of road conditions.</div>

A Novel Sleeve Design to Reduce the Eddy Current Loss of High-Speed Electrical Machines

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying the retaining sleeve to the rotor is essential. However, when using sleeves, there is a problem of reducing efficiency due to eddy current loss. In this paper, a study was conducted on a motor for a 100 kW building air conditioning system operating at a speed of 20,000 rpm. The purpose of the study is to reduce eddy current loss by optimizing the sleeve geometry. To this end, 3D finite element analysis (FEA) using JMAG 22.1 was conducted to analyze eddy current loss, the minimum safety factor was analyzed through mechanical stiffness analysis using ANSYS Workbench, and the validity of sleeve shape was proved through cause analysis. Through the research results, it is expected that the shape change of the sleeve will have the effect of reducing eddy current loss.

Sensorless Scheme for Permanent-Magnet Synchronous Motors Susceptible to Time-Varying Load Torques

This paper is devoted to designing a sensorless high-speed tracking control for surface-mount permanent-magnet synchronous motors, considering a time-varying load torque. This proposal consists of an extended-state observer interconnected with a PI-compensated controller, considering only the measurement of electrical variables for feedback. First, to design the extended-state observer, a rotary coordinate model of the motor is extended in one state to estimate the load torque and the rotor’s position and speed. Later, the estimations are fedback to a PI-compensated controller to attenuate the time-varying load torques. Our proposed methodology aims to overcome a restriction regarding the solution of the Riccati equation respecting the Lipschitz condition for observer stability analysis. Therefore, a PI-compensated controller described as a closed-loop provides a sensorless scheme. Lyapunov stability analysis is applied to determine sufficient conditions to ensure that the states of the closed-loop system are ultimately bounded, which is one of our main contributions. The proposed observer-based controller scheme deals with unmeasured load torque fluctuations. Furthermore, we carry out high-precision emulations to provide testing scenarios of the permanent-magnet synchronous motor with some challenging load torque magnitudes and behaviors. Finally, we conduct experiments on the Technosoft® development platform to corroborate the feasibility of the proposed control scheme in a real-world scenario.

First-Order Model Based Inductance Identification With Least Square Method for High-Speed Sensorless Control of Permanent Magnet Synchronous Machines

In sensorless control of high-speed permanent magnet synchronous machines (PMSMs), online inductance identification techniques can be employed to improve the position estimation precision. The high-order inductance identification model which is affected by the flux error, the dead-time effect equivalent voltage and initial rotor position error adopted in conventional methods often face challenges including robustness and accuracy. To address this issue, this paper uses a first-order discrete-time model in the estimated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γδ</i> -frame to identify the winding inductance with disturbance injection. The first-order model allows the identification to be independent of flux error, initial rotor position error and inverter nonlinearity, thus the robustness is improved. The proposed method takes the computational delay and discrete-time nature of pulse-width-modulation into account to avoid the model error brought by low ratio of carrier-to-fundamental-frequency. Additionally, the results are estimated by least square method to solve fluctuation problem caused by measurement noise and the possible surge phenomenon. Experiments are carried out on a high-speed surface-mounted PMSM for vacuum cleaner to verify the proposed method.

Research on a Novel High-Torque-Density Axial–Radial-Flux Permanent-Magnet Motor with Annular Winding for an Elevator-Traction Machine

The traditional radial flux PMSM and axial flux PMSM have an effective air gap on only one side, between the stator and rotor, and only the effective air gap generates electromagnetic torque. There are defects in the magnetic-field utilization, and it is difficult to improve the torque density. Therefore, this paper proposes an axial–radial-flux permanent-magnet synchronous motor (ARF-PMSM), which combines radial flux with axial flux, to be used in an elevator-traction machine-drive motor. The characteristics of the ARF-PMSM are that the stator core is made of a soft magnetic composite material and the winding is annular. The motor has three effective air gaps, which can achieve high torque density without increasing the overall dimensions. In this paper, the mechanical structure and operation mechanism of the ARF-PMSM are introduced, and the characteristics of its magnetic circuit structure are analyzed by using the equivalent magnetic circuit method. The torque characteristics and other electromagnetic characteristics of the ARF-PMSM, the traditional surface-mounted PMSM, and the spoke-type PMSM are compared and analyzed using the finite element method. The research results show that the proposed motor has high torque density, which provides a new design idea in the form of a high-torque-density PMSM for use in elevator-traction machines.

Estimated position correction algorithm of surface-mounted permanent-magnet synchronous motor based on variable gain steepest gradient descent method

This paper addresses the position-estimation deviation issue of the sensorless drive method and a new algorithm for estimating position correction of surface-mounted permanent magnet synchronous motor (SPMSM) is proposed. To improve the estimation accuracy of sensorless methods, the estimated position correction algorithm based on variable gain steepest gradient descent position error observer is proposed in this paper. The position error is estimated by the flux observation, and the steepest gradient descent method is used to correct the integration process. In addition, the dynamic and accuracy performance of the position error observer are improved by variable gain cycle iterative optimization. Experimental evaluation validated the effectiveness of the proposed algorithm, and the results show that the proposed method has the characteristics of high position observation accuracy and strong robustness.

Amplitude-Phase Based Optimal Voltage Harmonic Injection for Speed Harmonic Minimization in SPMSM

Low torque ripple level is the prerequisite for surface-mounted permanent magnet synchronous machines (SPMSM) to maintain control accuracy and speed stability. Since the speed harmonic's amplitude is proportional to the torque harmonic's amplitude, torque ripple can be reduced by speed harmonic minimization. Harmonic injection method is a practical speed harmonic minimization method. But current harmonic regulation and complex theoretical derivation are required in existing methods. What's more, the effectiveness of many methods will deteriorate when the parameters of PMSM and PI controllers vary. In order to avoid the influence of parameter variations and complex algorithms, an amplitude-phase based optimal voltage harmonic injection method is proposed for speed harmonic minimization in this paper. The influence of the injected voltage harmonic's amplitude and phase on the speed harmonic's amplitude is firstly analyzed. And then a simple speed harmonic controller based on the optimization of injection voltage harmonic's amplitude and phase is designed. The proposed method does not rely on the motor parameters. Moreover, the proposed method is easy to implement. It does not need to regulate current harmonics. The proposed method is simulated and experimentally evaluated under both steady-state and transient conditions.