Magnet-assisted Synchronous Reluctance Motor Research Articles

Maximum Torque Control of Permanent Magnet-Assisted Synchronous Reluctance Motor Using Fuzzy PI

Abstract This paper proposes a fuzzy PI-based Maximum Torque Per Ampere (MTPA) control for Permanent Magnet-Assisted Synchronous Reluctance Motor (PMASynRM). The aim is to address issues such as overshooting and slow response in the operation of the PMASynRM by optimizing MTPA control under traditional PI using a fuzzy PI control algorithm. This approach enhances the system’s responsiveness and disturbance rejection capabilities. The article builds a simulation model for the maximum torque-to-current ratio control of PMASynRM using fuzzy PI control in MATLAB/Simulink, comparing it with traditional PI control. Simulation results indicate that the fuzzy PI motor control system exhibits lower overshoot, faster response speed, and better robustness compared to traditional PI control.

Electromagnetic analysis of permanent magnet-assisted synchronous reluctance motor based on magnetic equivalent circuit

As rare-earth permanent magnet prices continue to fluctuate, interest in non-rare-earth permanent magnet-assisted synchronous reluctance motors (PMa-SynRMs) is increasing. However, non-rare-earth PMa-SynRMs have a multi-layer structure with interior permanent magnets to compensate for the low magnetic fields. Therefore, the rotor has several design parameters, and electromagnetic analysis is time-consuming. To overcome these challenges, magnetic equivalent circuit analysis was used to perform fast electromagnetic analysis of non-rare-earth PMa-SynRMs. In addition, the validity of the proposed method was confirmed through a comparison of the obtained results with those of finite element analysis.

Multi-Objective Optimization Design of the External Rotor Permanent Magnet-Assisted Synchronous Reluctance Motor Based on the Composite Algorithm

Based on the complex structural characteristics of permanent magnet-assisted synchronous reluctance motors (PMA-SynRMs), this paper proposes a multi-objective optimization design method for the motor using a composite algorithm. Firstly, the power density, electromagnetic torque, cogging torque, and torque fluctuation coefficient were used as optimization targets based on parametric analysis data of 14 motor structure variables, where parametric sensitivity analysis helped select eight optimization variables. Secondly, the motor prediction model was fitted using the genetic algorithm–back propagation (GA-BP) neural network. Finally, non-dominated sorting genetic algorithm-III (NSGA-III), based on the reference points, was used to find the optimization of the prediction model and complete the multi-objective optimization design of the external rotor PMA-SynRM with eight inputs and four outputs. A comparative analysis of the electromagnetic performance of the motor before and after optimization verifies the feasibility of optimizing the motor using the composite algorithm. This paper provides an analytical tool for the multi-parameter and multi-objective PMA-SynRM optimization design.

Performance Validation of PM Assisted SynRM and PMSM with Optimized Design for EV Application

This paper presents the comparison of Permanent Magnet-Assisted Synchronous Reluctance Motor (PMASynRM) and Permanent Magnet Synchronous Motor (PMSM) for the same design parameters and the evaluation of various performance parameters based on the Finite Element (FE) Method. FE Analysis is conducted after selecting the optimized design for PMASynRM and PMSM using an FE tool, with loading conditions to determine various performance parameters. This is achieved by maintaining the same motor dimensions and stator parameters while altering the rotor geometry for both motors. The final simulation results are discussed, and other performance parameters are recorded for comparison purposes. A PMASynRM is introduced, in which the problems of Synchronous Reluctance Motor (SynRM) can be eliminated with a permanent magnet in the rotor flux barrier. Due to higher flux barriers in PMASynRM, the reluctance torque is higher than in PMSM. If the magnet is placed very near to the air gap in PMSM, higher magnet torque is achieved, but due to the high reluctance torque in PMASynRM, the electromagnetic torque of PMASynRM is higher compared to PMSM. The research proves that the proposed design of PMASynRM is the best choice for Electric Vehicle (EV) applications. For PMASynRM, the shape of the flux barrier is not possible to change due to the design limitation of the FE software tool. Further analysis can be conducted by changing the shapes of the flux barriers to propose the most effective barriers. Basic theory and FE analysis of conventional PMSM and SynRM are reported in the literature. An optimal design is proposed through comparative analysis for EV applications to find out the best candidate for an EV motor.

Intelligent Backstepping Control of Permanent Magnet-Assisted Synchronous Reluctance Motor Position Servo Drive with Recurrent Wavelet Fuzzy Neural Network

An intelligent servo drive system for a permanent magnet-assisted synchronous reluctance motor (PMASynRM) that can adapt to the control requirements considering the motor’s nonlinear and time-varying natures is developed in this study. A recurrent wavelet fuzzy neural network (RWFNN) with intelligent backstepping control is proposed to achieve this. In this study, first, a maximum torque per ampere (MTPA) controlled PMASynRM servo drive is introduced. A lookup table (LUT) is created, which is based on finite element analysis (FEA) results by using ANSYS Maxwell-2D dynamic model to determine the current angle command of the MTPA. Next, a backstepping control (BSC) system is created to accurately follow the desired position in the PMASynRM servo drive system while maintaining robust control characteristics. However, designing an efficient BSC for practical applications becomes challenging due to the lack of prior uncertainty information. To overcome this challenge, this study introduces an RWFNN as an approximation for the BSC, aiming to alleviate the limitations of the traditional BSC approach. An enhanced adaptive compensator is also incorporated into the RWFNN to handle potential approximation errors effectively. In addition, to ensure the stability of the RWFNN, the Lyapunov stability method is employed to develop online learning algorithms for the RWFNN and to guarantee its asymptotic stability. The proposed intelligent backstepping control with recurrent wavelet fuzzy neural network (IBSCRWFNN) demonstrates remarkable effectiveness and robustness in controlling the PMASynRM servo drive, as evidenced by the experimental results.

Vibration and Noise Optimization of New Asymmetric Modular PMaSynRM

This study proposes an optimized structure to weaken the vibration and noise of a new asymmetric permanent magnet-assisted synchronous reluctance motor (PMaSynRM). The new asymmetric PMaSynRM has the advantages of a low torque ripple and high fault tolerance. However, the asymmetric structure generates an unbalanced magnetic force (UMF), which results in vibration and noise problems. In this study, the vibration and noise of the motor are analyzed and optimized. First, the radial pressure is analyzed, and an optimized structure is proposed. The electromagnetic performance of the motor before and after optimization is analyzed using the finite element method. Second, a three-dimensional model is established, and modal analysis is conducted considering the orthotropy of the stator and effective windings. Finally, the vibration and noise are simulated and analyzed, and the validity of the analysis results is verified experimentally. The analysis results indicate that the optimized motor realizes a reduction in the motor vibration and noise.

Design of Permanent Magnet-Assisted Synchronous Reluctance Motor with Low Torque Ripple

Permanent magnet-assisted synchronous reluctance motors (PMSRMs) have been widely used in household appliances, national defense and the military, due to their advantages of low cost and high efficiency. However, their excessive torque ripple cause a series of problems, such as high vibration and noise. To solve this problem, this paper first considers the important factor that causes the torque ripple—the cogging torque. Firstly, the generating principle of the cogging torque is analyzed, and a method combining magnetic pole migration and the stator auxiliary groove is proposed. On this basis, considering the position, width, depth, quantity and shape of the auxiliary groove, the Taguchi method is used to optimize the proposed improved structure. Finally, a new motor structure that can minimize torque ripple is obtained. Compared with the original structure, the cogging torque is reduced by 57.6%, the torque ripple is reduced by 38%, and the electromagnetic torque is only reduced by 1.6%.

Design and Experimental Performance Assessment of an Outer Rotor PM-Assisted SynRM for the Electric Bike Propulsion

Brushless dc motor (BLDCM) is a conventional machine type used in the electric bike (e-bike) industry due to its simple controllability and drive system. However, the fluctuating price and scarcity of NdFeB magnets used in BLDCMs, lower power density compared to ac machines, and high torque ripple have pushed researchers in industry and academia to investigate technology alternatives to BLDCMs in e-bike applications. Permanent magnet-assisted synchronous reluctance motor (PMaSynRM) is an attractive option to this end because of its adjustable reluctance torque component and the recent advancements in finite-element (FE)-based design algorithms and implementation. Not yet covered in the existing literature and industry reports for e-bike applications, an in-hub outer rotor PMaSynRM is designed in this article to improve the power density and reduce the torque ripple characteristics for replacing a 500-W commercial BLDCM. The designed PMaSynRM is fabricated and tested to validate the power density and torque ripple improvements compared to an existing Golden Motor MP2 BLDCM counterpart.

A Modified Permanent Magnet-Assisted Synchronous Reluctance Motor Design for Torque Characteristics Improvement

A modified configuration for Permanent Magnet Assisted Synchronous Reluctance Motors (PMaSyRM) is studied in this paper. Conventionally, the PM materials are inserted in the flux barriers region of the rotor. Consequently, the PMs sizing parameters will be restricted to the available space that may limit the efficient use of PMs benefits. In this study, a portion of the rotor structure is replaced with an Interior PM (IPM) rotor so that an axially segmented integration of IPM and SyRM is obtained. Thus, the PMs design is performed specifically in the IPM segment independent of the SyRM scheme, while the SyRM segment remains PM-less. The main motivation of this concept is to improve the contribution of the PM material in the total torque as well as utilizing the special property of the proposed rotor configuration for pulsating torque reduction. A computationally cost-effective algorithm is proposed for the optimal design of IPM-SyRM motor by which a low-power design is carried out for a lightweight electric vehicle. The results for torque profile characteristics, PM volume, power-factor, and efficiency are compared with a conventional PMaSyRM that has been optimally designed as the reference case. Finally, a prototype is constructed to verify the theoretical analysis.

Analysis of Permanent Magnet-assisted Synchronous Reluctance Motor Based on Equivalent Reluctance Network Model

In this paper, the equivalent reluctance network model (ERNM) is used to calculate the magnetic circuit of a permanent magnet-assisted synchronous reluctance motor (PMASynRM) and calculate no-load air-gap magnetic field and electromagnetic torque. Iteration method is used to solve the relative permeability of iron core. A novel reluctance network model based on actual distribution of the magnetic flux inside the motor is established. The magnetomotive force (MMF) generated by armature winding affects the relative permeability of iron core, which is considered in the calculation of ERNM to improve the accuracy when the motor is under load. ERNM can be used to measure air-gap flux density, no-load back electromotive force (EMF), the average value of motor torque, the armature winding voltage under load, and power factor. The method of calculating the motor performance is proposed. The results of calculation are consistent with finite element method (FEM) and the computational complexity is much less than that of the FEM. The results of ERNM has been verified, which will provide a simple method for motor design and analysis.

Performance Comparison of Fault-Tolerant Control for Triple Redundant 3 × 3-Phase Motors Driven by Mono-Inverter

In this article, the fault-tolerant control (FTC) strategy based on current redistribution is compared for three types of triple redundant <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times 3$ </tex-math></inline-formula> -phase motor: surface-mounted permanent magnet synchronous motor (SPMSM), synchronous reluctance motor (SynRM), and permanent magnet-assisted synchronous reluctance motor (PMa-SynRM), under a single-phase open-circuit fault. The output torque of SPMSM and SynRM is produced by permanent magnet (PM) torque and reluctance torque, respectively. Nevertheless, for PMa-SynRM, it is necessary to determine the distribution ratio of PM torque and reluctance torque in the proposed FTC strategy. By comparing the FTC performance of motors, the conclusions are as follows: 1) torque ripple of the SPMSM can be completely suppressed; 2) torque ripple minimization for the SynRM and PMa-SynRM can be realized; and 3) optimal solution obtained in SynRM can also be applied to the PMa-SynRM when the load is heavy. In addition, to reduce the complexity and improve the reliability of the control system, a mono-inverter-driven triple-paralleled control system is constructed in healthy and postfault operations. The comparison results of the FTC strategy for three types of motor are obtained by simulation. And the experimental results based on a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\,\times \,3$ </tex-math></inline-formula> -phase PMa-SynRM are accomplished to verify the feasibility of the theory.

Design, Modeling, and Model-Free Control of Permanent Magnet-Assisted Synchronous Reluctance Motor for e-Vehicle Applications

This paper describes the model-free control approaches for permanent magnet-assisted (PMa) synchronous reluctance motors (SynRMs) drive. The important improvement of the proposed control technique is the ability to determine the behavior of the state-variable system during both fixed-point and transient operations. The mathematical models of PMa-SynRM were firstly written in a straightforward linear model form to show the known and unknown parts. Before, the proposed controller, named here the intelligent proportional-integral (iPI), was applied as a control law to fix some unavoidable modeling errors and uncertainties of the motor. Lastly, a dSPACE control platform was used to realize the proposed control algorithm. A prototype 1-kW test bench based on a PMa-SynRM machine was designed and realized in the laboratory to test the studied control approach. The simulation using MATLAB/Simulink and experimental results revealed that the proposed control achieved excellent results under transient operating conditions for the motor drive’s cascaded control compared to traditional PI and model-based controls.

Maximum Torque per Ampere Control of Permanent Magnet Assisted Synchronous Reluctance Motor: An Experimental Study

In recent times, permanent magnet assisted synchronous reluctance motors (PMaSRM) have been considered as suitable traction motors for electric vehicle applications. In this type of machine, where the share of reluctance torque is more significant than the excitation torque, it is more appropriate to use a control strategy that can fully utilize the reluctance torque. This paper deals with a new structure of permanent magnet-assisted synchronous reluctance motors that was designed and manufactured in a previous study. This paper suggests applying, in a first study, a constant parameter maximum torque per ampere (MTPA) strategy to make a contribution towards the control of such structure that is becoming increasingly attractive in the field of electric transportation. This method is usually used to control interior permanent magnet synchronous motors to minimize the copper losses of the system. Before implementing and simulating this method, the mathematical models of the suggested motor and the inverter are given. An experimental study is conducted on a small-scale 1 kW prototype PMaSRM using a MicrolabBox Dspace to test and examine the proposed control. Simulation and experimental results are presented in this article in order to verify the validity of the developed control strategy.

Design, Modeling, and Differential Flatness Based Control of Permanent Magnet-Assisted Synchronous Reluctance Motor for e-Vehicle Applications

This paper presents the utilization of differential flatness techniques from nonlinear control theory to permanent magnet assisted (PMa) synchronous reluctance motor (SynRM). The significant advantage of the proposed control approach is the potentiality to establish the behavior of the state variable system during the steady-state and transients operations as well. The mathematical models of PMa-SynRM are initially proved by the nonlinear case to show the flatness property. Then, the intelligent proportional-integral (iPI) is utilized as a control law to deal with some inevitable modeling errors and uncertainties for the torque and speed of the motor. Finally, a MicroLab Box dSPACE has been employed to implement the proposed control scheme. A small-scale test bench 1-KW relying on the PMa-SynRM has been designed and developed in the laboratory to approve the proposed control algorithm. The experimental results reflect that the proposed control effectively performs high performance during dynamic operating conditions for the inner torque loop control and outer speed loop control of the motor drive compared to the traditional PI control.

Estimation of the main dimensions of the traction permanent magnet-assisted synchronous reluctance motor

Goal. The goal of the research is to develop an algorithm for selecting the main dimensions of a traction permanent magnet-assisted synchronous reluctance motor. Methodology. A method for determining the main dimensions of the motor, which combines the analytical selection of stator parameters and numerical field calculations for the selection of rotor parameters. The need to check the mechanical strength of a rotor with permanent NdFeB magnets in flux barriers is shown. Results. The article proposes an algorithm for selecting the main dimensions of a traction permanent magnet-assisted synchronous reluctance motor, which combines analytical expressions for selecting stator parameters and numerical field calculations for selecting rotor parameters. It is determined that analytical methods for calculating the magnetic circuit need to be developed in order to reduce the time to select the main dimensions of the motor. Originality. For the first time the sizes of active parts of the permanent magnet-assisted synchronous reluctance motor with power of 180 kW for the drive of wheels of the trolleybus are defined. Practical significance. As a result of research the sizes of active parts, stator winding data and a design of a rotor of the electric motor are defined. The obtained results can be applied when creating an electric motor for a trolleybus.

Design of External Rotor Ferrite-Assisted Synchronous Reluctance Motor for High Power Density

The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea.

Rotary Shaft Encoder Inaccuracy Compensation for PMA-SynRM Drives Application Using Augmented State UKF

The use of permanent magnet-assisted synchronous reluctance motor (PMA-SynRM) is increasing due to its advantages and superiority over induction motors. The undesirable effects of the encoder measurement error on the drive systems especially during low-range speeds may cause disorder in drive performance and sometimes its instability. For the low-cost application that requires a low-resolution encoder, this problem is felt obviously. This article presents a mathematical solution in order to compensate for the instability problem of a PMA-SynRM control at low speeds based on an augmented state unscented Kalman filter (ASUKF). First, a mathematical analysis for the effect of encoder error on the speed control instability is performed, and then an augmented nonlinear dynamical model for the PMA-SynRM is derived. Using an ASUKF on the presented augmented model of the PMA-SynRM, the error of the encoder is detected and accurately estimated. Using the estimated errors and pure motor state variables, the accuracy and robustness of the control are increased and its stability is guaranteed. The experiments performed for a 0.35 kW PMA-SynRM confirm the performance validity of the proposed method.

A Novel Modular Permanent Magnet-Assisted Synchronous Reluctance Motor

This paper proposes a novel modular permanent magnet-assisted synchronous reluctance motor (MPMA-SynRM) structure. The rotor is composed of two types of rotor modules that are axially combined. This article analyses and explains the combined angle of the axial assembly of different rotor modules. The MPMA-SynRM rotor module is optimized using a differential evolution algorithm and the MPMA-SynRM space vector diagram is established to give the torque calculation an analytical expression. Whether there is axial magnetic isolation between different rotors is analysed, and various segment numbers, pole arc coefficients, and length ratios are used for different rotor modules to affect the electromagnetic influence of the MPMA-SynRM's cogging torque. Detailed analyses of the MPMA-SynRM loss, efficiency, and permanent magnet demagnetization state are given. The no-load back EMF, power factor, efficiency, eddy current loss, and cogging torque of the MPMA-SynRM with traditional Nd-Fe-B permanent magnet motors and permanent magnet auxiliary synchronous reluctance motors are compared, and a prototype is made to prove the performance of this motor.

Analytical design, electromagnetic field analysis and parametric sensitivity analysis of an external rotor permanent magnet-assisted synchronous reluctance motor

This paper deals with analytical design, electromagnetic field analysis and parametric sensitivity analysis of an external rotor permanent magnet-assisted synchronous reluctance motor (PMASynRM). In this work, parametric sensitivity analysis of rotor geometry is performed to obtaining the minimum torque ripple and maximum electromagnetic torque with employing numerical analysis based on two-dimensional finite element method (FEM). In order to determine the optimum operation effect of geometry parameters like the q axis insulation ratio and the flux barrier arm angle for the proposed machine with three barriers is investigated and sensitivity of structure for rotor geometrical variation is presented. The studied machine in this work is a three phase, six pole, external rotor PMASynRM, which is designed by analytical approach and analyzed to obtain the maximum torque and minimum torque ripple based on a parametric sensitivity analysis approach. The obtained results from the FEM-based sensitive analysis and electromagnetic field analysis confirm the analytical design procedure for the proposed PMASynRM.

Electromagnetic-Thermal Coupled Simulation Under Various Fault Conditions of a Triple Redundant 9-phase PMASynRM

This article performs electromagnetic (EM) and thermal coupled simulation based on two-dimensional (2-D) transient electromagnetic and 3-D thermal model of a triple redundant nine-phase permanent magnet-assisted synchronous reluctance motor under various fault conditions at different speeds. The coupled simulation process is controlled by a scripting file. The resultant temperatures under EM-thermal coupled simulation will be comprehensively compared with those under thermal-only simulation. The predicted current waveforms under fault conditions by the 2-D EM model and predicted temperatures by the 3-D thermal model will be compared with the test results for validation. The outcomes of the study not only gives a better understanding of the thermal behavior, but also provides a guidance to the necessity of the EM-thermal coupled simulation under different fault conditions as well as to determination of the maximum permissible fault detection time before permanent damage due to the fault may occur.