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This paper investigates a robust detection for demagnetization fault in the permanent-magnet synchronous motor (PMSM). A proportional-integral fading sliding-mode observer (PIFSMO) is proposed, which can solve the problem of PMSM performance degradation caused by the permanent-magnet demagnetization and resistance disturbance increase during long-term operation. A PMSM demagnetization model is established, and an improved PIFSMO is proposed to detect the demagnetization flux linkage. A fading integral term is added to the traditional sliding-mode observer, which can suppress the offset in the resistance disturbance estimation caused by transients, thereby achieving direct estimation of the resistance disturbance and the slowly varying resistance disturbance (e.g., ḋ≠0) in particular. Simulation and experimental results demonstrate the feasibility and effectiveness of the proposal. [ABSTRACT FROM AUTHOR]

This paper focuses on the speed regulation of permanent magnet synchronous motors (PMSM) in electric vehicle application using sliding mode control (SMC). Harris hawks optimizations (HHO) based sliding mode controller is adopted to increase the dynamic response of the PMSM motor, thereby enhancing vehicle performance. For the independent control of torque and flux, field oriented-control (FOC) is used to drive the PMSM. In this work, the speed reference provided for the controller is based on an electric car driving cycle that replicates real-world driving conditions. The optimal selection of sliding mode controller parameter enhances the dynamic characteristics of the speed regulation in electric vehicles, which is validated using the hardware in the loop (HIL-402) device. The HHO based sliding mode controller has superior performance in terms of robustness against load disturbances, fast convergence, and tracking accuracy.

Hyperparameter tuning requires trial and error, which is time consuming. This study employed a one-dimensional convolutional neural network (1D CNN) and Design of Experiments (DOE) using the Taguchi method for optimal parameter selection, in order to improve the accuracy of a fault-diagnosis system for a permanent-magnet synchronous motor (PMSM). An orthogonal array was used for the DOE. One control factor with two levels and six control factors with three levels were proposed as the parameter architecture of the 1D CNN. The identification accuracy and loss function were set to evaluate the fault-diagnosis system in the optimization design. Analysis of variance (ANOVA) was conducted to design multi-objective optimization and resolve conflicts. Motor fault signals measured by a vibration spectrum analyzer were used for fault diagnosis. The results show that the identification accuracy of the proposed optimization method reached 99.91%, which is higher than the identification accuracy of 96.75% of the original design parameters before optimization. With the proposed method, the parameters can be optimized with a good DOE and the minimum number of experiments. Besides reducing time and the use of resources, the proposed method can speed up the construction of a motor fault-diagnosis system with excellent recognition. [ABSTRACT FROM AUTHOR]

The series-winding permanent-magnet synchronous motor (SW-PMSM) has the merits of high output power and excellent control performance, as does the open-winding permanent-magnet synchronous motor (OW-PMSM). Meanwhile, it can greatly reduce the number of power devices. However, due to the existence of the zero-sequence path, zero-sequence current occurs, which can cause additional losses and torque ripples. Thus, this paper proposes a novel direct torque-control strategy for the SW-PMSM with zero-sequence current suppression capability (ZSCS-DTC). First, the series-winding topology (SWT) and the voltage vector distribution in the SW-PMSM drives are analyzed. Secondly, the basic DTC (B-DTC) scheme for the SW-PMSM is investigated, and the defects of zero-sequence current open-loop control in the B-DTC scheme are revealed. Thirdly, a new voltage vector synthesis scheme is proposed for suppression of zero-sequence current while ensuring bus voltage utilization. A switching table is reconstructed with the newly synthesized voltage vectors. On this basis, a ZSCS-DTC scheme for the SW-PMSM is proposed based on zero-sequence current closed-loop control so that electromagnetic torque, stator flux linkage and zero-sequence current can be controlled simultaneously. Finally, the effectiveness of the proposed ZSCS-DTC scheme for the SW-PMSM drives is verified. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the control of marine permanent-magnet propulsion motors, active disturbance rejection control has attracted much attention because it can deal with external load disturbances and uncertainties of motor parameters at the same time. However, the conventional second-order ADRC has the problem of slow disturbance observation speed. To this end, this paper proposes an improved third-order extended state observer using the proportional–integral disturbance update law to improve the tracking performance and anti-external disturbance ability of the motor control system. Then, aiming at the problem that the structure does not effectively use the current information, resulting in large speed fluctuations when the load changes, the measured value of the q-axis current is used as the disturbance feedforward compensation item to further improve the load disturbance suppression ability of the motor. Finally, in order to suppress the influence of the current periodic disturbance caused by unmodeled dynamics on the steady-state accuracy of the motor, a nonlinear switching function with bounded gain and an IIR low-pass filter are designed to suppress the periodic disturbance without affecting the dynamic performance of the system. Combined with the established ship propeller load model, the effectiveness of the method is verified on the motor experimental platform: When suddenly changing 75% of the propeller load, the motor speed decreases by about 20%, and the adjustment time is 0.1 s, which improves the performance by more than 70% compared to PI control and conventional ADRC methods. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) strategy can provide significant benefits for controlling nonlinear systems over classical cascade field-oriented control (FOC). However, the MPC is still in the development stage for a high-performance predictive model. Therefore, the proposed MPC in this article updates the internal linear predictive model at each time step to accurately represent the nonlinear plant of a permanent-magnet synchronous motor (PMSM) plant over different speed regions. In other words, the adaptive discrete linear plant model (ADLPM) is designed to update the current operating conditions of the machine parameters and the equilibrium points of the measured stator currents, speed, and load torque. For the operation in the flux-weakening region, the proposed MPC depends on a performance control algorithm (PCA) to obtain high dynamic performance. In this PCA algorithm, the proposed MPC depends on the modified reference velocity rather than the original reference velocity, which can calculate the required d-axis current directly. Moreover, the proposed cost function is designed directly in terms of the error values of the velocity and d-axis current, which fits the motor performance based on the further constraint of the maximum magnitude of the drawn stator current provided to control the acceleration of the rotor. Finally, comprehensive simulations and experiments have fully demonstrated that the proposed MPC can reduce the speed drop, and torque ripple in response to those of the FOC and traditional MPC strategies. [ABSTRACT FROM AUTHOR]

This study presents a maximum torque per ampere (MTPA) control method for a mono inverter dual parallel (MIDP) surface-mounted permanent-magnet synchronous motor (SPMSM) drive system. The multimotor drive system has been extensively studied, because it can drive moreover two motors using only one inverter, reducing the costly power conversion circuit. However, existing studies concerning MIDP permanent-magnet synchronous motor drive systems focus on stabilizing the system, and studies regarding efficiency optimization are difficult to find. Some studies have shown the efficiency-optimizing method, but implementing is challenging because of the complicated calculations and algorithm. The proposed control method can achieve efficiency-optimizing operation using the angle difference controller. The angle difference controller controls the angle difference of two motors to an optimal value. Furthermore, the optimal angle difference of two motors can be easily obtained regardless of parameter errors, using the perturbation and observation algorithm. The proposed MTPA strategy is verified by performing simulations using matlab Simulink and applying the method to an actual MIDP SPMSM drive system. [ABSTRACT FROM AUTHOR]

This article proposes a modified flux observer for sensorless direct torque control (DTC) of the dual three-phase permanent-magnet synchronous motor. The proposed method can improve torque performance without a position sensor. The flux observer is proposed to obtain the stator fluxes and rotor fluxes. The stator fluxes can be utilized to calculate the amplitude of torque and flux for DTC system. Meanwhile, the position information can be detected from the rotor fluxes by using a normalized phase-locked loop. This new flux observer can overcome the disadvantages due to the dc bias, initial value, and harmonic components. The stability of the proposed observer is also analyzed in this article. In addition, a fault-tolerant DTC scheme for open-circuit fault is introduced. The performances of torque control and position estimation are evaluated under healthy, open-circuit fault, and fault-tolerant conditions. Simulation and experimental evaluation are carried out to confirm the effectiveness of the proposed sensorless DTC scheme. [ABSTRACT FROM AUTHOR]

This article proposes a modified deadbeat predictive current control (M-DPCC) method to improve the dynamic performance of permanent magnet synchronous motor (PMSM). Classical DPCC only predicts one control cycle of the PMSM, which restricts the dynamic performance since multiple control cycles are required for the transient state under heavy load and rated speed working condition. The proposed M-DPCC extends the single-step prediction to the entire dynamic interval in the transient state, by which the comprehensive optimization on the angle of the stator voltage vector can be implemented. Moreover, M-DPCC performed multi-step deadbeat calculation to keep the computation modest. To verify the effectiveness of the proposed M-DPCC, transient-state performance of PMSM using the M-DPCC method, the modulated model predictive control and classical DPCC are explored under a wide range of working condition. Comparative simulation and experimental results indicate that dynamic performance of the PMSM can be improved, especially under rated speed and heavy load conditions. Besides, the parameter sensitivity to inductance mismatch of the three methods is carried out. The stable operation range of the M-DPCC under inductance mismatch is larger than the other two methods. Moreover, the computation complexity of the three methods were investigated. The M-DPCC acquired less computation time than the modulated model predictive control. [ABSTRACT FROM AUTHOR]

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.

In the control of marine permanent-magnet propulsion motors, active disturbance rejection control has attracted much attention because it can deal with external load disturbances and uncertainties of motor parameters at the same time. However, the conventional second-order ADRC has the problem of slow disturbance observation speed. To this end, this paper proposes an improved third-order extended state observer using the proportional–integral disturbance update law to improve the tracking performance and anti-external disturbance ability of the motor control system. Then, aiming at the problem that the structure does not effectively use the current information, resulting in large speed fluctuations when the load changes, the measured value of the q-axis current is used as the disturbance feedforward compensation item to further improve the load disturbance suppression ability of the motor. Finally, in order to suppress the influence of the current periodic disturbance caused by unmodeled dynamics on the steady-state accuracy of the motor, a nonlinear switching function with bounded gain and an IIR low-pass filter are designed to suppress the periodic disturbance without affecting the dynamic performance of the system. Combined with the established ship propeller load model, the effectiveness of the method is verified on the motor experimental platform: When suddenly changing 75% of the propeller load, the motor speed decreases by about 20%, and the adjustment time is 0.1 s, which improves the performance by more than 70% compared to PI control and conventional ADRC methods.

This article proposes a straightforward and effective control strategy to reduce the periodic speed ripple of the permanent-magnet synchronous motor. The control strategy can be described as injecting current harmonics whose amplitude and phase can be adjusted automatically to compensate for periodic speed ripple. Compared with the resonant controller with the Tustin transform, the method proposed in the article can track speed ripple frequency without frequency displacement, realizing no steady-state error. Besides, the system stability is analyzed, and the phase compensation scheme is proposed to increase the phase stability. Moreover, the equivalence between the harmonic injection module and the resonant controller has been analyzed, which provides a simple way to understand the phase compensation of the resonant controller. The theoretical analysis and experimental results are presented to verify the feasibility of the proposed harmonic injection method. [ABSTRACT FROM AUTHOR]

Aiming at the electromagnetic vibration and noise problem of an 8-pole 48-slot permanent magnet synchronous motor for a vehicle, the multi-physics coupling simulation model of the motor is introduced to optimize the rotor structure of the motor to reduce the vibration and noise of the permanent magnet synchronous motor. The effectiveness of the research method is verified by the bench test in the anechoic chamber. Finite element software was used to establish the stator core and system model considering the anisotropy of materials, and the simulation model was verified by modal experiment. For the 2in1 electric drive system, the electromagnetic-structure-acoustic multi-physics coupling noise prediction model is established. Based on the three-dimensional distributed electromagnetic force excitation, the electromagnetic radiation noise of the motor under full load acceleration is calculated, and the characteristics of electromagnetic noise are analyzed. The accuracy of the electromagnetic-structure-acoustic multi-physics coupling model of permanent magnet synchronous motor is verified by the bench test results of the anechoic chamber. By changing the angle and shape of the motor rotor, the cogging torque ripple between the stator and the rotor is reduced, and the 48th order harmonic amplitude is reduced. Finally, the optimized sample is tested on the vehicle, and the 48th order electromagnetic noise can be reduced by 5–15 dB(A). The accuracy of the electromagnetic-structure-acoustic multi-physics coupling model of permanent magnet synchronous motor is verified by the bench test results of the anechoic chamber. Therefore, the research results can be further used for the design and development of a vehicle permanent magnet synchronous motor and the research on the mechanism of electromagnetic vibration and noise. [ABSTRACT FROM AUTHOR]

This study presents a variable incremental controller for flux-weakening control in the high-speed operation area of a permanent-magnetic synchronous motor (PMSM). In general, voltage-based flux-weakening control utilizes a reference voltage and a PI controller to generate a flux component current. In this paper, the voltage-based flux-weakening control is performed using the variable incremental controller instead of the PI controller. The variable incremental controller can control the flux component current using only the maximum speed and maximum current of the motor. A method for properly setting an appropriate variable incremental controller using acceleration is additionally presented. A variable incremental controller is applied and, accordingly, the overshoot of the motor speed can be reduced and the speed error of the motor can be minimized by reducing the difference between the actual motor and targeted accelerations. This method can simplify the design of a controller that utilizes flux-weakening control and can be applied to railroad cars whose acceleration does not alter frequently to increase the effect of motor control. [ABSTRACT FROM AUTHOR]

Addressing the problem of the vibration and noise of a permanent-magnet synchronous motor (PMSM), this paper optimizes the structure of a permanent-magnet motor rotator, introduces the electromagnetic-structure-acoustic coupling calculation model, and optimizes the motor rotator to reduce the vibration and noise of a permanent-magnet motor. Using the theory of Maxwell's stress equation, the radial electromagnetic force on the stator teeth of the permanent-magnet motor is deduced and analyzed, and the correctness of the analysis calculation is verified by using the finite element multi-physical field coupling method. Based on the deduced analytical expression of the radial electromagnetic force, the sources of the radial electromagnetic force for each order and the frequency of the permanent-magnet motor are summarized. A 12-slot, 8-pole, permanent-magnet motor is taken as an example. A calculation model considering the spatial distribution of the radial electromagnetic force and the electromagnetic vibration of an iron-cobalt-based stator is established. The harmonic response of the electromagnetic vibration of the motor is analyzed, and a modal analysis is carried out. The optimized acceleration vibration noise cascade of the FeCo-based permanent-magnet drive motor under load is given. The correctness and validity of the theoretical derivation and simulation are verified by experiments. [ABSTRACT FROM AUTHOR]

The single current sensor operation (SCSO) has attracted widespread attention in the motor drive system because of its ability to reduce cost and volume. However, when the SCSO is used with the conventional space vector puleswidth modulation (SVPWM) technique, the current reconstruction unobservable area in the sector boundary and low modulation area will degrade the accuracy of sampling data. In this article, a mixed SVPWM (MSVPWM) control scheme is proposed to eliminate the unobservable area. With the proposed scheme, the zero vectors (${{{\bm V}}_{{\rm {0}}}}$ and ${{{\bm V}}_{{\rm {7}}}}$) are replaced by the complementary effective vectors to achieve the same effect in the sector boundary and low modulation area, and the SVPWM is applied to the remaining space vector plane. These inserted effective vectors make the current observation window time prolonged to ensure that the dc-link current data can be accurately acquired in the entire space vector plane. Hence, the high-quality reconstruction of the phase current can be realized with less impact on the output of current ripples and reconstruction errors. Moreover, the relationship between the rotation speed and the increase in switching losses under different switching frequencies is quantitatively analyzed. The effectiveness of the MSVPWM reconstruction algorithm was verified by experimental results obtained from a permanent-magnet synchronous servo motor. [ABSTRACT FROM AUTHOR]

In permanent-magnet synchronous motor (PMSM) drives, many current control strategies are presented to compensate the effects of rotor flux distortion on torque performance. These strategies are usually realized in the synchronously rotating reference frame and at least two-phase current sensors are used. Although the technique of phase current reconstruction enables three-phase currents to be obtained with a single dc-link current sensor, two-phase current controllers and complex coordinate transformations are still necessary. In this article, a simplified current control strategy for low-power PMSM drives is proposed. First, a torque allocation law is designed to resolve the reference electromagnetic torque into the reference three-phase currents with compensation for rotor flux distortion. Second, the reference three-phase currents are further converted into the reference dc-link current according to the averaging theory. Third, the amplitude and waveform control of three-phase currents are fulfilled by using dc-link current controller and ac-side pulsewidth modulation, respectively. This strategy can compensate the effects of rotor flux distortion on torque performance and is easy to implement with only one current sensor and one controller. Simulation and experimental results demonstrate the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

This article analyzes the effect of discretization in the frequency-adaptive flux observer (FAO). Although FAO has structural simplicity and ease of implementation, the discrete-time FAO has phase and gain errors in fundamental flux estimation. As a result, the estimated flux might be erroneous, especially in the high-speed region. For accurate flux estimation, this article analyzes how the voltage synthesis in the pulsewidth-modulation affects the stator flux. Through the analysis, the backward Euler method is selected for the primitive stator flux estimation. To mitigate the FAO's discretization error, the proposed FAO utilizes the integrators constructed at the rotor reference frame (RRF). Since the discretization error comes from the approximation error of the continuous-time integrator at the operating frequency, the proposed FAO conducts the fundamental flux extraction at the RRF, where the operating frequency components are treated as a dc signal. Thanks to the coordinate transformation, the FAO can be discretized with no error while keeping the structure of double integrators. The proposed method is verified through the computer simulation and experimental test. [ABSTRACT FROM AUTHOR]

The deadbeat control is one of the widely concerned control methods for the permanent-magnet synchronous motor (PMSM) due to its fast dynamic performance. However, its control performance relies heavily on the accuracy of the PMSM model parameters, which may vary with the operation cases. In this article, a novel online parameter identification algorithm is proposed for the PMSM deadbeat control. First, an identification model is established to estimate the parameter errors from the offsets of the deadbeat control, in which the nonlinearity of the voltage source inverter is fully concerned. Then, a novel “parameter perturbation method” is proposed for gathering the essential data to solve the rank deficient problem in the parameter identification process. It does not need to inject additional instructions in the control, resulting in no impact on the normal operation of the PMSM. The Adaline neural network is employed to achieve the online acquisition of parameter identification results. Finally, the effectiveness and superiority of the proposed algorithm are verified by experimental results on a PMSM platform. [ABSTRACT FROM AUTHOR]

In order to obtain satisfactory transient and steady-state performances, a hybrid dual-mode control (HDMC) is proposed for surface-mounted permanent-magnet synchronous motor drives (PMSMs), which contains two control modes. The first one is the deadbeat predictive control (DBPC) mode, which is only implemented in the transient procedure. The second one is the field-oriented control (FOC) mode, which is mainly implemented in the steady-state operation. Besides, the FOC mode is also implemented in the transient procedure to eliminate the static current error. In the transient procedure, the FOC mode is activated after one-sampling-period implementation of the DBPC mode in the unsaturation state, and the desired voltage vector calculated in this sampling period is assigned as the initialized values of the proportional-integral current controllers in the FOC mode to avoid the switching chattering. When the voltage-source-inverter comes into the saturation state, the DBPC mode will be reactivated immediately. The proposed HDMC inherits the quick response ability of DBPC and the good steady-state performances of FOC. The effectiveness of the proposed HDMC is verified by the experimental results.

This article presents a robust adaptive optimal tracking control (RAOTC) scheme for permanent-magnet synchronous motor (PMSM) servo drive with uncertain dynamics via adaptive dynamic programming (ADP) method. First, an adaptive identifier is developed to estimate the nonlinear dynamic functions of the PMSM using a functional-link neural-network. Then, the proposed RAOTC scheme is developed that combines an adaptive steady-state controller, an adaptive optimal tracking controller, and a robust controller. The adaptive steady-state controller is designed for attaining the targeted tracking response at the steady-state using the estimated nonlinear dynamics. The adaptive optimal tracking controller is designed for stabilizing the tracking error dynamics at the transient state in an optimal manner. Further, the robust controller is developed for compensating the approximation errors of neural-networks introduced by implementing the ADP technique. Accordingly, actor and critic neural-networks are employed for facilitating the online solution of the Hamilton-Jacobi-Bellman equation for approximating the adaptive optimal control (OC) laws via ADP method. Based on Lyapunov approach, the closed-loop stability of the PMSM servo drive system is proved to demonstrate that the proposed RAOTC scheme can ensure the system state tracking the targeted trajectory effectively. The proposed RAOTC scheme validation is performed via experimental analysis. From the experimental validation results, the PMSM servo drives dynamic behavior using the proposed RAOTC scheme can attain the robust and OC performance regardless the compounded disturbances and parameter uncertainties. [ABSTRACT FROM AUTHOR]

The accurate estimation of mechanical parameters is essential for the control optimization and condition monitoring of permanent-magnet synchronous motor (PMSM) drives. In this article, an online parallel estimation scheme is proposed based on a network of three interconnected extended sliding-mode observers. With a two-step mechanism derived from the developed network, this scheme can simultaneously achieve the accurate real-time observation of three mechanical parameters, including the viscous friction coefficient, the moment of inertia, and the load torque. The first step utilizes the presented network to precisely acquire the Coulomb friction coefficient by offering only one speed. With aiding from this estimated coefficient, the second step attains the high-precision online identification of the three concerned parameters by compensating the Coulomb friction torque to counteract its adverse effect. These two steps are implemented utilizing the identical network, thus, furthest avoiding increasing the estimation complexity. Besides, any additional knowledge other than the rotor speed and electromagnetic torque is no longer required for guaranteeing the asymptotic convergence of the estimation errors. Sufficient evaluations from simulations and experiments confirm the validity of the proposed scheme. [ABSTRACT FROM AUTHOR]

Aiming at the electromagnetic vibration and noise problem of an 8-pole 48-slot permanent magnet synchronous motor for a vehicle, the multi-physics coupling simulation model of the motor is introduced to optimize the rotor structure of the motor to reduce the vibration and noise of the permanent magnet synchronous motor. The effectiveness of the research method is verified by the bench test in the anechoic chamber. Finite element software was used to establish the stator core and system model considering the anisotropy of materials, and the simulation model was verified by modal experiment. For the 2in1 electric drive system, the electromagnetic-structure-acoustic multi-physics coupling noise prediction model is established. Based on the three-dimensional distributed electromagnetic force excitation, the electromagnetic radiation noise of the motor under full load acceleration is calculated, and the characteristics of electromagnetic noise are analyzed. The accuracy of the electromagnetic-structure-acoustic multi-physics coupling model of permanent magnet synchronous motor is verified by the bench test results of the anechoic chamber. By changing the angle and shape of the motor rotor, the cogging torque ripple between the stator and the rotor is reduced, and the 48th order harmonic amplitude is reduced. Finally, the optimized sample is tested on the vehicle, and the 48th order electromagnetic noise can be reduced by 5–15 dB(A). The accuracy of the electromagnetic-structure-acoustic multi-physics coupling model of permanent magnet synchronous motor is verified by the bench test results of the anechoic chamber. Therefore, the research results can be further used for the design and development of a vehicle permanent magnet synchronous motor and the research on the mechanism of electromagnetic vibration and noise.

This study presents a variable incremental controller for flux-weakening control in the high-speed operation area of a permanent-magnetic synchronous motor (PMSM). In general, voltage-based flux-weakening control utilizes a reference voltage and a PI controller to generate a flux component current. In this paper, the voltage-based flux-weakening control is performed using the variable incremental controller instead of the PI controller. The variable incremental controller can control the flux component current using only the maximum speed and maximum current of the motor. A method for properly setting an appropriate variable incremental controller using acceleration is additionally presented. A variable incremental controller is applied and, accordingly, the overshoot of the motor speed can be reduced and the speed error of the motor can be minimized by reducing the difference between the actual motor and targeted accelerations. This method can simplify the design of a controller that utilizes flux-weakening control and can be applied to railroad cars whose acceleration does not alter frequently to increase the effect of motor control.

Balancing the dc-link voltage and three flying-capacitor (FC) voltages while maintaining very fast control of the motor is always a challenging task in five-level active neutral-point-clamped (5L-ANPC) converter-fed permanent-magnet synchronous motor drives, especially when the FC is small. Besides, the fundamental-frequency operation of the low-frequency cell (LFC) is also required to reduce the losses of the converter. This article proposed a two-stage optimization-based model predictive control (MPC) scheme to achieve these goals. In the first stage, the switching states of the LFC are selected based on the sign of the desired output voltage through a deadbeat approach for its fundamental-frequency operation; in the second stage, the optimal duty cycles for the high-frequency cell are calculated by the multiple-vector MPC and generated by phase-shifted pulsewidth modulation for its fixed-switching frequency operation. The FC and dc-link capacitor voltage balance can be managed by the flexibility of the inherent redundancy in the 5L-ANPC converter. Instead of 512, only six switching vectors must be considered, which significantly simplifies the computational burden of MPC. A thorough experimental evaluation has been conducted to validate the effectiveness of the proposed MPC method. [ABSTRACT FROM AUTHOR]

Controlling a three-level neutral-point-clamped (3L-NPC) inverter-fed permanent-magnet synchro-nous machine (PMSM) drive is a challenging task, especially when the dc-link voltage is unbalanced. The unbalanced dc-link voltages, which are with some of the voltage vectors varying in magnitude and phase, lead to highly distorted stator current. In this article, a two-stage model predictive control (MPC) is proposed for the 3L-NPC inverter-fed PMSM drive. In the proposed MPC method, control of the 3L-NPC inverter is decoupled into two stages. In the first stage, three switching states are determined by small hexagon selection using finite control set MPC. The rest switching states are controlled using the multiple vector MPC in the second stage. In the two-stage MPC, the number of switching state evaluations can be significantly reduced, and the nonlinearity caused by the unbalanced dc links can be included in the duty cycle optimization process, leading to improved output current quality under unbalanced dc links and reduced computational burden. Moreover, the output switching frequency is fixed due to the employment of the multiple vector MPC. A thorough experimental evaluation of the proposed MPC method with the deadbeat control with the pulsewidth modulation strategy has been conducted to validate the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Model predictive current control (MPCC) is a high-performance control strategy for permanent-magnet synchronous motor (PMSM) drives, with the features of quick response and simple computation. However, the conventional MPCC results in high torque and current ripples. This article proposes an improved MPCC scheme for PMSM drives. In the proposed scheme, the back electromotive force is estimated from the previous stator voltage and current, and it is used to predict the stator current for the next period. To further improve the steady state and dynamic performance, the proposed MPCC selects the optimal voltage vector based on a current track circle instead of a cost function. Compared with the calculation of cost function, the prediction of the current track circle is simple and quick. The proposed MPCC is compared with conventional MPCC and a duty-circle based MPCC by simulation and experiment in the aspect of converter output voltage and sensitivity analysis. Results prove the superiority of the proposed MPCC and its effectiveness in reducing the torque and current ripples of PMSM drives. [ABSTRACT FROM AUTHOR]

Accurate rotor position is necessary for high-performance control of a permanent-magnet synchronous motor. Compared with the methods using position sensors to detect rotor position, the sensorless methods can simplify the motor structure and enhance the reliability. To improve the estimation accuracy of sensorless methods, the position error correction method based on the low-order harmonic suppression is proposed in this article. The low-order harmonics generated by the position error are analyzed in detail, which will cause extra motor losses. The position error signal can be reconstructed by low-order harmonics that are extracted by rotating the frame transformation and low-pass filter. And the estimated position can be corrected using the reconstructed signal. The proposed method can not only improve the position estimation accuracy, but also suppress the low-order harmonics, which can reduce motor losses and enhance the motor performance. Based on space vector pulsewidth modulation, the proposed method is independent of motor parameters. It can be applied to the sensorless methods that can obtain voltages. The position error correction method has well dynamic performance and great robustness. The effectiveness is verified by the experiments on the turbo molecular pump. [ABSTRACT FROM AUTHOR]

Addressing the problem of the vibration and noise of a permanent-magnet synchronous motor (PMSM), this paper optimizes the structure of a permanent-magnet motor rotator, introduces the electromagnetic-structure-acoustic coupling calculation model, and optimizes the motor rotator to reduce the vibration and noise of a permanent-magnet motor. Using the theory of Maxwell’s stress equation, the radial electromagnetic force on the stator teeth of the permanent-magnet motor is deduced and analyzed, and the correctness of the analysis calculation is verified by using the finite element multi-physical field coupling method. Based on the deduced analytical expression of the radial electromagnetic force, the sources of the radial electromagnetic force for each order and the frequency of the permanent-magnet motor are summarized. A 12-slot, 8-pole, permanent-magnet motor is taken as an example. A calculation model considering the spatial distribution of the radial electromagnetic force and the electromagnetic vibration of an iron-cobalt-based stator is established. The harmonic response of the electromagnetic vibration of the motor is analyzed, and a modal analysis is carried out. The optimized acceleration vibration noise cascade of the FeCo-based permanent-magnet drive motor under load is given. The correctness and validity of the theoretical derivation and simulation are verified by experiments.

In permanent-magnet synchronous motor (PMSM), the winding current consists of different orders of harmonics due to the manufacture error, deadtime, and disturbances. This article proposes a winding current harmonic suppression method for PMSM by reducing the dominant fifth- and seventh-order current ripples. First, with reference frame transformation, the fifth- and seventh-order current ripples convert to sixth-order ripples in the synchronous reference frame (SRF). Then, with further transformation, these sixth-order ripples turn to dc signals. Next, the type-II Chebyshev filter is designed to extract these dc signals. Also, the proportional–integral (PI) controller is adopted to generate the current harmonic control voltage, which is setting the dc current harmonic signals reference to be zero. Finally, the current harmonic control voltage is compensated to the voltage reference in the SRF. Both the simulation and experimental results are presented to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This article proposes an indirect method for predicting mechanical loss by considering the eddy current loss of permanent magnets (PMs) and conductors under the no-load condition. The mechanical loss has been conventionally predicted indirectly through experiments and numerical methods. The conventional method uses the no-load loss measured through experiments and the no-load iron loss calculated through a numerical method. With the increase in the demand for high-power-density motors, the PMs with high energy density and winding technology with high fill factor are required. Thus, the proportion of eddy current losses of PMs and conductors is increasing among the electromagnetic losses. Therefore, we propose an indirect method for predicting the mechanical loss considering the eddy current losses. The accuracy of the proposed method is higher than that of the conventional method. Moreover, the proposed method is verified by comparing the estimated efficiency of the specimen obtained by using this method with the measured efficiency. [ABSTRACT FROM AUTHOR]

To improve the tracking performance of the current controllers of permanent-magnet synchronous motor (PMSM) drive systems that are subject to internal disturbances, such as parameter variations, a novel active-disturbance-rejection-based sliding-mode current control (ADR-SMCC) scheme for PMSM drives is proposed in this article. First, a fast-response SMCC is designed based on the upper bound of the internal disturbance. Then, an extended state observer (ESO) is designed to estimate the internal disturbance in real time without the need for an accurate mathematical model of the PMSM. The parameters of the ESO can be easily designed based on the desired bandwidth of the ESO. The estimated internal disturbance is then used to update the control law of the SMCC in real time. The resulting ADR-SMCC has improved steady-state and transient current tracking performance and enhanced robustness to internal disturbances. The stability of the closed-loop PMSM drive system with the ADR-SMCC is proven by the Lyapunov theory. The ADR-SMCC is validated by experimental results for a 200-W salient-pole PMSM drive system. [ABSTRACT FROM AUTHOR]

Excellent control performance and high robustness under different operating conditions are primary purposes pursued by many model predictive control algorithms. As a model-based control algorithm, the accuracy of the stator current mathematical model has a significant impact on the control performance of the predictive current control (PCC) method. To improve the current tracking accuracy and the robustness against parameter variation, a stator current mathematical model self-regulation strategy, which uses stator current prediction error to calculate parameter changes and design a parameter variation compensation strategy to correct the mathematical model in real-time at each control cycle, based on PCC algorithm is proposed to pursue desired performance. Consequently, the elimination of stator current prediction error, high controlled quality, and better robustness have been achieved in the proposed method. The comparative simulation and experiment results validate the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

In model predictive control, mathematical model of the system is used to predict the value of state variables. Control performances of model predictive control suffer from parameter mismatches and model uncertainties. Steady-state errors will exist due to inaccurate predictions. This article presents a simple predictive current control strategy for robustness improvement of finite control set-model predictive control, with which steady-state errors under parameter mismatches can be eliminated. Neither disturbance observer nor explicit solution of compensation voltage is needed in the proposed control strategy. A cost function is newly designed, which is in proportional-integral form. Moreover, the integral action is only activated in a predefined range, which facilitates the design of the integral coefficients. The accumulated error is not simply included but weighted with the sampling time. In this way, a careful selection of the number of integral terms to be included in the cost function is not required. Experimental results demonstrate superior robustness of the proposed current control strategy to that of conventional predictive current control against parameter uncertainties. [ABSTRACT FROM AUTHOR]

In this article, we evaluate the noise and vibration in a permanent-magnet synchronous motor (PMSM) with distributed winding driven by voltage source pulsewidth modulation (PWM) inverters. Although the PMSM is a widely used device in a variety of fields, it tends to generate electromagnetic noise and vibration due to the PWM inverters. We describe the frequency of the electromagnetic vibration to estimate the worst point of the carrier electromagnetic vibration of dc voltage fluctuation. The PWM voltage harmonics and the modulation degree of dc voltage fluctuation were investigated through a theoretical analysis of the PWM voltage harmonics. It was found that a modulation degree near 0.56 was the maximum point of the doubled component of the carrier frequency $2f_{c}$. Compared with the dc voltage fluctuation at this point, the dominant component of the PWM voltage harmonics was near frequency $f_{c}$ at a lower voltage and near frequency $2f_{c}$ at a higher voltage. These tendencies of the carrier electromagnetic vibration of dc voltage fluctuation are also verified in an experiment. [ABSTRACT FROM AUTHOR]

This paper presents a new fault tolerant control FTC scheme of Permanent Magnet Synchronous Motor drive. A sensorless position predictive torque control (PTC) based on Sliding Mode-MRAS estimator is used for three-phase four-switch (B4) inverter-fed PMSM, which connects the neutral of the motor to the midpoint of the DC-Link voltage source. Current observer is used to reconfigure the drive when one current sensor is available in the proposed inverter topology. The main contribution of the proposed strategy relies on the fact that no reconfigurations or modifications of the converter topology and controller are required from normal operation to post-fault operation. Simulation results are presented to verify the validity of the proposed control strategy. [ABSTRACT FROM AUTHOR]

In this article, the conventional flux sliding-mode observer (FSMO) is modified by taking the motor parameter variations into consideration, and an embedded flux observer is constructed to replace the conventional phase-locked loop for estimating the speed and position in the permanent-magnet synchronous motor (PMSM) sensorless control system. Compared with conventional FSMO, the improved method has certain robustness to parameter variations and improves the dynamic performance of the system under speed reversal. Furthermore, in the real experimental environment, after the long-term operation, the increasing of the motor temperature changes the values of the stator resistance and inductance. This phenomenon mismatches the actual and the setting motor specifications, which may induce ripples in the estimation results and affect the system stability. To address this issue, an online parameter estimation method is proposed in this article and incorporated into the modified FSMO to improve system performance and eliminate parameter mismatching. The control scheme of a PMSM prototype based on the proposed method is designed, and the corresponding experimental platform is built; the performance of the proposed method is validated and compared with that of the conventional FSMO via simulations and experiments. [ABSTRACT FROM AUTHOR]

This paper focuses on current control in a permanent-magnet synchronous motor (PMSM). This paper has two main objectives: the first objective is to develop a neural-network (NN) vector controller to overcome the decoupling inaccuracy problem associated with the conventional proportional–integral-based vector-control methods. The NN is developed using the full dynamic equation of a PMSM, and trained to implement optimal control based on approximate dynamic programming. The second objective is to evaluate the robust and adaptive performance of the NN controller against that of the conventional standard vector controller under motor parameter variation and dynamic control conditions by: 1) simulating the behavior of a PMSM typically used in realistic electric vehicle applications and 2) building an experimental system for hardware validation as well as combined hardware and simulation evaluation. The results demonstrate that the NN controller outperforms conventional vector controllers in both simulation and hardware implementation. [ABSTRACT FROM AUTHOR]

This paper presents an improved rotating restart method for a sensorless permanent magnet synchronous motor (PMSM) drive system using repetitive zero voltage vectors. To restart the sensorless PMSM drive system, a method for estimating initial rotor position and speed is required due to the absence of sensors such as encoders and resolvers. The rotor position and speed can be estimated using the short-circuit current vectors generated by applying zero voltage vectors. However, the estimated rotor position and speed can be inaccurate. The inaccurate rotor position that causes the current is distorted by the back-electromotive force of the PMSM, and it is impossible to precisely control the system. Therefore, an improved rotating restart method for the sensorless PMSM drive system using repetitive zero voltage vectors is proposed. The effectiveness of the proposed method is verified through simulation and experimental results using a 5-kW PMSM drive system. [ABSTRACT FROM AUTHOR]

A novel Model Order Reduction (MOR) technique is developed to compute high-dimensional parametric solutions for electromagnetic fields in synchronous machines. Specifically, the intrusive version of the Proper Generalized Decomposition (PGD) is employed to simulate a Permanent-Magnet Synchronous Motor (PMSM). The result is a virtual chart allowing real-time evaluation of the magnetic vector potential as a function of the operation point of the motor, or even as a function of constructive parameters, such as the remanent flux in permanent magnets. Currently, these solutions are highly demanded by the industry, especially with the recent developments in the Electric Vehicle (EV). In this framework, standard discretization techniques require highly time-consuming simulations when analyzing, for instance, the noise and vibration in electric motors. The proposed approach is able to construct a virtual chart within a few minutes of off-line simulation, thanks to the use of a fully separated representation in which the solution is written from a series of functions of the space and parameters coordinates, with full space separation made possible by the use of an adapted geometrical mapping. Finally, excellent performances are reported when comparing the reduced-order model with the more standard and computationally costly Finite Element solutions.

This paper proposes a predictive speed and current control with multi-timescale optimization in a cascade architecture for a permanent-magnet synchronous motor. Considering the difference of timescale characteristics for speed loop and current loop, different sampling times are assigned to the respective subsystem. In the prediction step of the conventional two-timescale system, the coupling between slow and fast sampling models is ignored and the output of the slow-sampling model at asynchronous sampling period is missing, which both weaken the prediction performance of the system. In this paper, the predictions of both slow and fast models for all the prediction instants are analyzed in detail. Besides, a linear estimation method based on virtual instants is proposed to improve the performance of the slow-sampling model for fast prediction instants. The data stream of the proposed method is designed based on the cascaded structure. The strategies are implemented on a field-programmable gate arrays taking advantages of parallel and pipeline processing techniques. Experimental results show that the proposed strategies have a better dynamic performance compared to the conventional method. [ABSTRACT FROM AUTHOR]

This paper proposes a new single-current-sensor (SCS) control method for a permanent-magnet synchronous motor (PMSM) driven by a quasi-Z-source inverter (qZSI). In this method, the sum of two branch currents in the inverter is sampled by an SCS twice for one control period, under actions of two different shoot-through voltage vectors. Then, the three-phase currents of the motor can be reconstructed by these two sample values and can be later used for the current closed-loop control of the PMSM. In this paper, the feasibility of the SCS control method is analyzed thoroughly and a corresponding modulation strategy is given for the qZSI. Compared with the traditional SCS control methods, the new method fully eliminates the measurement dead-zone problem without any additional compensation strategy. The operation range of the PMSM extends and utilization rate of the input voltage improves. In conclusion, the proposed method is easy and convenient to implement, which makes itself a promising application in electrical vehicles. [ABSTRACT FROM AUTHOR]

Winding currents contain lots of harmonics if motors rotate at a high speed. This paper addresses two key challenges on the harmonic suppression: 1) using the multiple synchronous rotating frame transformations (MSRFTs) to get the primary signals, and 2) proposing the closed-loop detection system (CDS) to extract the harmonics accurately. First, the mathematical model containing the harmonics was built. Second, the MSRFTs were introduced and the high-precision detection method called the CDS was analyzed. The CDS has a higher harmonic detection accuracy than the open-loop method and can enhance the disturbance rejection capability of the system. Third, the parameter-independent compensation algorithm was proposed to enhance the robustness against the motor parameter variations, which was combined with the compensation calculated by the mathematical model to suppress the harmonics. The effectiveness of the proposed harmonic suppression strategy was verified by the experiments on the turbo molecular pump. [ABSTRACT FROM AUTHOR]

Under the noncascade structure, a permanent-magnet synchronous motor (PMSM) regulates the speed and current in one loop. On the one hand, fast dynamic performance requires large transient current to provide a high torque. On the other hand, unlike a cascade control, the q-axis current is no longer governed by a reference current signal. In such a system, the nominal controllers cannot guarantee that the q-axis current is within the required range. But an excessively large transient current may threaten the circuit safety. To solve the overcurrent protection problem, the ordinary solution is to choose conservative control parameters, but the dynamic performance inevitably suffers a certain degree of loss. In order to improve this drawback, a simple and effective control scheme is introduced with a current-constrained technique. By constructing a special nonlinear gain, the punishment mechanism for the q-axis current is established in the control action directly. The proposed control approach does not impose limitations on the initial state. Moreover, it has good robustness to load torque uncertainty and undergoes rigorous theoretical analysis. Besides, the proposed current-constrained controller has a very concise structure. It yields a higher reliability of the PMSM control system. Comparative simulation and experimental results between the classic PID and the current-constrained controller on the PMSM servo system verify the feasibility of the presented control scheme. [ABSTRACT FROM AUTHOR]