Surface-mounted Permanent Magnet Synchronous Motor Research Articles

Multidisciplinary Design Optimization of the Actuation System of a Hybrid Electric Aircraft Powertrain

In the context of hybrid electric and full electric powertrains for future less-pollutant aircrafts, this paper focuses on the multidisciplinary design optimization (MDO) of the actuation system, including a surface-mounted PMSM in order to maximize the power density of the device: this study is a preliminary approach before integrating the whole powertrain. After an introduction of the MDO context, the analytical model of the electric motor is detailed. It integrates multi-physical aspects (electric, magnetic, mechanical, thermal, partial discharges and insulation, control and flight mission) and takes several heterogeneous design constraints into account. The optimization method involves a genetic algorithm allowing the reduction of the actuation weight with regard to a wide set of constraints. The results show the crucial sensitivity of the electro-thermal coupling, especially the importance of transient modes during flight sequences due to thermal capacitance effects. Another major point is related to the performance of the thermal cooling, which requires the introduction of an “internal cooling” in the stator slots in addition to the “base cooling” for stator and rotor. Gathering these analyses, the MDO leads to high power density actuators beyond 15 kW/kg with high-voltage–high-speed solutions, satisfying all design constraints (insulation, thermal, magnet demagnetization) over the flight mission.

Sliding Mode Direct Torque Control of SPMSMs Based on a Hybrid Wolf Optimization Algorithm

Direct torque control has been widely used to control surface-mounted permanent magnet synchronous motors (SPMSMs). To reduce the torque ripple and improve the flux tracking accuracy of SPMSM drives, sliding mode direct torque control (SMDTC) was developed. However, its optimal performance is hardly obtained by trial and error tuning of the control parameters. Hence, a hybrid wolf optimization algorithm (HWOA) is proposed to automatically adjust the controller's parameters of SMDTC for SPMSMs in this article. This algorithm combines the grey wolf optimization algorithm and coyote optimization algorithm. A conversion probability is designed to use them simultaneously. The proposed HWOA holds the advantages of the two algorithms. It converges very fast and can avoid local optimums effectively. Furthermore, a special fitness index with penalty terms is designed to enhance flux tracking accuracy and reduce the torque ripple of SPMSM drives. The superiority of the proposed control method is verified by an experiment.

Energy Management and Control System Design of an Integrated Flywheel Energy Storage System for Residential Users

This paper presents the energy management and control system design of an integrated flywheel energy storage system (FESS) for residential users. The proposed FESS is able to draw/deliver 8 kWh at 8 kW, and relies on a large-airgap surface-mounted permanent magnet synchronous machine, the inner rotor of which integrates a carbon-fiber flywheel, leading to a compact and efficient FESS. The proposed energy management system is based on four different operating modes, which are defined and can be selected in accordance with FESS speed and/or user’s preference, while FESS control system is devoted to power/current tracking at both machine- and grid-side converters. The effectiveness of the proposed solutions, as well as the overall energy performance of the proposed FESS, are verified by real-time simulations, which regard different operating conditions and/or realistic scenarios.

Kriging Surrogate Model-Based Design of an Ultra-High-Speed Surface-Mounted Permanent-Magnet Synchronous Motor Considering Stator Iron Loss and Rotor Eddy Current Loss

Ultra-high-speed (UHS) surface-mounted permanent-magnet synchronous motors (SPMSMs) are widely used for driving air compressors. UHS SPMSMs can suffer from high stator iron loss and rotor eddy current loss due to their high rotational speed and changes in the magnetic flux density when loading. Since these losses do not have a linear trend but change according to the motor design parameters, mathematical models cannot always predict them. This study aims to design UHS SPMSMs based on a kriging surrogate model that takes into account the stator iron loss and rotor eddy current loss. Since the kriging surrogate model is highly predictive for nonlinear inputs, it is the perfect candidate to take into account the stator iron loss and rotor eddy current loss. The design proposed in this study allowed to minimize the size and losses of a motor that satisfied the power specification.

Design and Validation of an Unconventional 39-Slot PM Synchronous Motor With Asymmetric and Unbalanced AC Windings

One of the main issues in manufacturing rotors for integer slot surface-mounted permanent magnet (PM) synchronous motors is the rotor skew. Motor manufacturers typically prefer to avoid skewing due to the added complexity and the difficulty in controlling the accuracy of the skewing and achieving the required outcome. This article proposes a design that minimizes torque ripple without using any kind of skewing in the rotor using asymmetric ac windings with unconventional stator slot-pole combinations. First, feasible slot and pole combinations are reviewed for PM synchronous motors. Theory behind unconventional asymmetric and unbalanced ac winding PM motors is presented. A lumped-parameter magnetic equivalent circuit for such unconventional stator is provided for a 1.7-kW PM motor. Detailed 2-D finite element analysis (FEA) is performed and compared with the lumped parameter model. A prototype motor is manufactured, and open-circuit as well as full-load tests are performed. Good agreement between the analytical, FEA, and test results is obtained.

An Improved Adaptive Selected Harmonic Elimination Algorithm for Current Measurement Error Correction of PMSMs

Measurement errors are inevitable in the current sensors, which cause speed ripple including one and twice the stator electrical frequency. For the undesired harmonics, the adaptive selected harmonic elimination (ASHE) algorithm outputs the sum of the sinusoidal signals multiplied by the adaptive weights. In order to solve the current measurement error (CME) issue, this article adopts the ASHE algorithm. According to the deterministic functional relationship of the surface-mounted permanent magnet synchronous motor (SPMSM), the adopted algorithm extracts the harmonics of the steady state speed error, and outputs the q-axis current compensation. However, there is no explicit connection between speed and d-axis current, so their relationship is uncertain. The remaining d-axis CMEs result in poor current performance. Therefore, this article proposes an improved ASHE algorithm, which compensates the dq-axis CMEs simultaneously depending on their mutual deterministic connection. The proposed method does not need motor parameters, additional sensors, or complex calculation process. Finally, the effectiveness of the method is verified by the SPMSM platform. Experimental results also show that the proposed method reduces speed ripple and suppresses the negative effects of CMEs.

Computationally Efficient PM Power Loss Mapping for PWM Drive Surface-Mounted Permanent Magnet Synchronous Machines

This paper proposes a computationally efficient approach for mapping permanent magnet (PM) power loss in permanent magnet synchronous machines (PMSMs). The PM loss mapping method here uses time-step finite element analysis (FEA) to determine the function parameters representing the loss variation with speed (frequency), amplitude modulation ratio, carrier ratio, and stator current and is suitable for rapid evaluation of machine performance over the entire torque–speed envelope. The PM loss can be accurately mapped across the full operational envelope, including the field-weakened mode. The loss mapping procedure takes into account the equivalent resistivity of axial segmentation of the PM array calculated by three-dimensional (3-D) FEA. The effect of temperature on the PM loss is also considered. The proposed methodology is validated on two surface-mounted PMSM designs. The results of the loss mapping procedure are consistent with those from direct 3-D finite element prediction and experimental results of PM power loss at each operating point of the machine.

Speed control of an SPMSM using a tracking differentiator-PID controller scheme with a genetic algorithm

In this paper, a tracking differentiator-proportional integral and derivative (TD-PID) control scheme is proposed to control the speed of a surface mount permanent magnet synchronous motor (SPMSM). The TD is used to generate the necessary transient profile for both the reference and the output speed, which are compared with each other to produce the error signals that feed into the PID controller. In addition to the TD unit parameters, the PID controller’s parameters are tuned to achieve the optimum new multi-objective performance index, comprised of the integral of the time absolute error (ITAE), the absolute square of the control energy signal (USQR), and the absolute value of the control energy signal (UABS) and utilizing a genetic algorithm (GA). A nonlinear model of the SPMSM is considered in the design and the performance of the proposed TD-PID scheme was validated by comparing its performance with that of a traditional PI controller in a MATLAB environment. Different case studies were tested to show the effectiveness of the proposed scheme, results including peak overshoot, energy consumption, control signal chatter, and 30% improvement in the OPI, with variable reference speeds, load torque, and parameters uncertainties. Illustrate the proposed scheme's success compared with PI controller.

An Online Flux Estimation for Dual Three-Phase SPMSM Drives Using Position-Offset Injection

The rotor flux linkage of permanent-magnet synchronous motor (PMSM) is of great importance for monitoring and high-performance control. However, most of the existing online estimation methods need prior knowledge of other PMSM parameters such as stator resistance and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> axis inductance, which are difficult to realize in the rank-deficient models of electrical machines. This article proposes a simple online estimation method of rotor flux linkage for the dual three-phase surface-mounted PMSM (SPMSM) drives with the assistance of injected position offset. The independent estimation model has been developed for the rotor flux linkage by appropriate setting of positon offset between two sets of three-phase windings of dual three-phase SPMSM drives. The proposed method not only has little influence on the output torque and high signal-to-noise ratio for observation, but also offers the superior performance in estimation accuracy irrespective of the influence of VSI nonlinearity. In addition, the proposed position-offset-based method is suitable for the full-speed region including the field-weakening operation. Finally, comprehensive experimental results are presented to verify validity of the proposed method under different working conditions.

Continuous adaptive integral-type sliding mode control based on disturbance observer for PMSM drives

This paper concerns the speed regulation problem for permanent magnet synchronous motor (PMSM) drive system with matched and mismatched disturbance. A novel single-loop speed and current control strategy with continuous integral-type terminal sliding mode control (ITSMC) and disturbance observer (DOB) is proposed. Firstly, the nonlinear motor model including the lumped disturbance is constructed. Then, by introducing a virtual control, a continuous integral-type sliding mode controller, which has the non-cascade structure, is developed based on terminal sliding mode surface, and it has the globally asymptotic stability based on Lyapunov criterion. However, when the drive system has large disturbance, especially for unmatched external disturbance, the performance of the whole system will be influenced. To further improve the anti-disturbance performance, a disturbance observer is introduced to estimate both the matched and mismatched disturbance in the system, and it is used for the feed-forward compensation, and the stability of the system is proved. Finally, the novel scheme is tested on a surface-mounted PMSM by experiment, and the comparative results in different operation conditions verify that the proposed method has the fast transient response and the strong robustness for the disturbance.

High-Order Terminal Sliding-Mode Observer for Chattering Suppression and Finite-Time Convergence in Sensorless SPMSM Drives

Due to the advantages of strong robustness and fast convergence, the sliding-mode observer (SMO) is considered as an effective approach for sensorless surface-mounted permanent magnet synchronous motor (SPMSM) drives. However, the inherent chattering and none finite-time convergence are still challenging problems in SMO application. To address these problems, this article proposed a high-order terminal SMO (HOTSMO) for SPMSM position estimation. First, a terminal sliding-mode surface is designed to achieve finite-time convergence of state variables. Second, a high-order sliding-mode control law is presented to achieve chattering suppression. Compared with the conventional SMO, the studied HOTSMO can achieve high estimation accuracy without sacrificing strong robustness of SMO. The effectiveness of the studied scheme is experimentally verified on a 4.4-kW ARM-based SPMSM platform.

2-D Analytical No-Load Electromagnetic Model for Slotted Interior Permanent Magnet Synchronous Machines

This paper presents a fast analytical model for estimating the components of the PM flux density distribution in the air-gap for a number of interior permanent magnet synchronous machines (IPMSMs). Deriving the two-dimensional (2-D) analytical model for IPMSMs is more challenging compared to that of surface-mounted permanent magnet synchronous machines (SPMSMs) due to the inconsistent geometry of the rotor in polar coordinates. IPMSMs are usually modeled by using 0-D or 1-D methods such as the magnetic equivalent circuit (MEC); however, the MEC method is unable to take into account the tangential component of the magnetic flux density vector. In this paper, a 2-D analytical no-load electromagnetic model for five rotor topologies of IPMSMs is proposed. The effects of the stator slots on the radial component of the PM flux density distribution in the air-gap are then included by defining an air-gap function. The effects of the stator slots on the tangential components of the PM flux density distribution in the air-gap are also considered by injecting virtual surface currents (VSCs) or virtual permanent magnets (VPMs). For verification purposes, the analytical results are compared with those of the finite element method (FEM) and the experimental results of one of the cases.

Innovative Fault-Tolerant Three-Phase SPMSM Drive Without Split Capacitors, Auxiliary Legs, or TRIACs

The existing fault-tolerant three-phase ac drives need split capacitors, auxiliary legs, and triode for alternating current (TRIACs) upon a standard three-phase two-level voltage source inverter (VSI) to obtain the self-healing ability toward open-phase faults (OPFs). In order to reduce the cost, volume, and weight, this article proposes a novel fault-tolerant three-phase surfacemounted permanent magnet synchronous machine (SPMSM) drive without split capacitors, auxiliary legs, or TRIACs. The proposed drive is still built upon a three-phase two-level VSI, whereas its dc-source is directly connected to the neutral point of the motor. First, mathematical model and equivalent circuit are established to reveal the existence of an equivalent dc/dc boost converter in the drive system. Second, the brand-new d-0 axes current references are proposed in order to preserve the motor's performance when an OPF occurs. In this case, both id and i0 are nonconstant. Third, an overall control strategy including the healthy and fault-tolerant modes is presented. In the fault-tolerant mode, a deadbeat current controller is developed to track the nonconstant current references. Finally, experiments are carried out on an SPMSM test-bench to verify the effectiveness of the proposed scheme.

Design of Ultra-High-Speed Motor for FCEV Air Compressor Considering Mechanical Properties of Rotor Materials

This paper proposes the design process of an ultra-high-speed surface-mounted permanent magnet synchronous motor for a fuel-cell electric vehicle air compressor. Proposed design process enables ultra-high-speed motor design while considering mechanical stresses of the rotor materials according to the temperature. In the rotor design stage, the worst temperature condition of the permanent magnet and retaining sleeve on mechanical stress is investigated and reflected using analytical method. Rotor dimension such as permanent magnet and retaining sleeve thickness is determined considering both electromagnetic performance and mechanical characteristics. Then, from the initially designed model, the eddy current loss according to the shape ratio (SR) and torque density (TD) is analytically derived using proportional equation and finite-element analysis result. Then, SR and TD to reduce the eddy current loss and maximize the efficiency are determined while considering the first bending critical speed. Finally, to verify the proposed design process, the prototype is fabricated and tested. Test results show good agreement with the finite-element analysis results, and it is confirmed that the rotor is operated at the highest rotational speed without mechanical failure.

An Online Estimation Method for Both Stator Inductance and Rotor Flux Linkage of SPMSM Without Dead-Time Influence

It is essential to estimate stator inductance and rotor flux linkage online for fault diagnosis and high-performance control of surface-mounted permanent magnet synchronous machine (SPMSM). Current injection method is a popular way to estimate the two parameters. However, the dead-time influence of voltage-source-inverter (VSI) and the stator inductance variation caused by injected current could not guarantee the converge of the estimation. To solve the above two problems, a method of injecting square-wave angle for online parameter estimation is proposed in this paper. Firstly, the theory of eliminating dead-time influence with and without square-wave angle injection is analysed. Next, the least square algorithm is adopted to estimate stator inductance without injection. Then the rotor flux linkage is estimated with injecting square-wave angle. The saturation effect on estimation is also analyzed and both parameters are estimated without acquiring any nominal values. At last, the appropriate amplitude and frequency of square-wave angle are determined by the parameter error and convergence analysis. The proposed method is evaluated with simulation and extensive experiments under various speed and load conditions. It is noteworthy that not less than two parameters are estimated without the dead-time influence and the injection will not cause inductance variation, which is different from the previous work.

Sensorless control of SMPMSM drive system integrated the differential algebra with the algebraic parameter identification

The differential algebraic sensorless control has the technical features of clear concept and low calculation amount. However, this method is particularly sensitive to motor parameters. Therefore, a differential algebraic sensorless control strategy combined with algebraic parameter identification is proposed and applied to surface mounted permanent magnet synchronous motor (SMPMSM) drive system in this paper. Without the signal injection, the proposed method can promptly and accurately realize the online simultaneous identification of stator resistance and inductance based on the different torque conditions of system, and then the motor parameters used in the differential algebraic sensorless control are updated in time. In addition, the tracking differentiator is designed to accurately obtain the first-order differential of the stator current signal with noises for rotor position estimation. Finally, the effectiveness of the proposed sensorless control method is validated by the simulation results.

VSI Nonlinearity Compensation of a PMSM Drive System Using Deadbeat Prediction Based Current Zero-Crossing Detection

Due to the nonlinearities of the voltage-source inverter (VSI) in a permanent magnet synchronous machine (PMSM) drive system, there is always an error between the reference voltage and the actual output voltage. To compensate the voltage error, many schemes have been proposed based on the phase current polarity. However, due to factors such as current clamping, measurement noises, and control system delay, the accuracy of the detected current polarity is relatively low, especially when the current is around zero, which would therefore affect the compensation performance. To solve this issue, a deadbeat prediction-based current zero-crossing detection method (DP-CZD) is proposed in this paper. With the proposed method, the measured three-phase currents are replaced by the predicted three-phase currents in terms of the polarity determination, when the absolute value of the phase current is within the threshold range. Compared with the conventional phase current polarity detecting methods, the proposed method can greatly improve the accuracy of detected current polarity due to its smooth transient waveform, and consequently, contributes to the much higher accuracy and lower total harmonic distortion (THD) in the compensation of VSI nonlinearity, which is verified through a prototype surface-mounted PMSM.

Improved Iterative Learning Direct Torque Control for Torque Ripple Minimization of Surface-Mounted Permanent Magnet Synchronous Motor Drives

This article presents an improved iterative learning direct torque control (IL-DTC) to remarkably minimize the torque ripples for a surface-mounted permanent magnet synchronous motor (SPMSM) drive. Unlike the conventional IL-DTC, the proposed IL-DTC significantly attenuates the torque ripples by effectively suppressing the repetitive disturbances using the speed and load torque compensating terms in the improved error dynamics via the improved feedback control terms and iterative learning control terms. Further, it has a simple structure and fast dynamic response due to the direct control of the torque and flux. The stability is verified through the convergence of speed errors to zero as the iteration index goes to infinity. The comparative results via MATLAB/Simulink and a prototype SPMSM test-bed with TI-TMS320F28335-DSP demonstrate the improved control performance (e.g., less torque ripples, faster transient response, smaller overshoot/undershoot, and smaller steady-state error) over the conventional IL-DTC under critical load/speed conditions with severe model parameter uncertainties.

Estimation Method for Rotor Eddy Current Loss in Ultrahigh-Speed Surface-Mounted Permanent Magnet Synchronous Motor

Surface-mounted permanent magnet synchronous motors (SPMSMs) usually adopt a retaining sleeve for ultrahigh-speed (UHS) applications. The retaining sleeve usually has high electrical conductivity and cannot be segmented. Accordingly, the rotor eddy current loss is high. Moreover, the higher the eddy current loss, the higher is the rotor temperature. Therefore, the rotor eddy current loss should be considered in the design stage. However, the eddy current loss is generally calculated through three-dimensional finite-element analysis (3-D FEA) and considered cumbersome because of the high computation time. This article proposes a simple estimation method for the rotor eddy current loss of a UHS SPMSM according to the motor size. In this study, the mechanically stable cross-sectional structure of the rotor was fixed, and a formula for predicting the eddy current loss of the rotor based on motor size was devised. In this method, the basic electromagnetic formula for eddy current and the frozen permeability method were utilized. The proposed method was validated via comparisons with the results of 3-D FEA.

Cogging torque reduction based on segmented skewing magnetic poles with different combinations of pole‐arc coefficients in surface‐mounted permanent magnet synchronous motors

The calculation and reduction of cogging torque are fundamental to the evaluation and optimisation of motor performance. Considering that the accuracy of the cogging torque calculated by analytical method (AM) is low, an accurate calculation model of the effective air-gap length considering the actual stator slot structure and suitable for any motor is proposed, the cogging torque of 6p36s surface-mounted permanent magnet synchronous motor (SPMSM) are calculated accurately and verified by finite element method (FEM). Furthermore, the segmented skewing magnetic poles with different combinations of pole-arc coefficients are designed to weaken cogging torque, and the optimal combination of pole-arc coefficients and tilting angle of the adjacent magnetic poles are summarised by AM and particle swarm optimisation (PSO) algorithm. Finally, the cogging torques of six SPMSMs with different slot-pole combinations including 6p36s, 4p36s, 6p9s, 8p9s, 8p12s and 10p12s are analysed, and the results indicate that the cogging torque can be greatly weakened based on segmented skewing magnetic poles with different combinations of pole-arc coefficients, and other performances of the motors are basically not affected.