Nonsalient Permanent Magnet Synchronous Machine Research Articles

Designing practical fuzzy gain scheduling controllers for micromobility applications of permanent magnet synchronous machines

In micromobility applications, maintaining satisfactory motor drive performance in the full torque-speed envelope of an outer rotor non-salient permanent magnet synchronous machine is a challenge due to the drastic performance degradation with the increasing non-linearity above the nominal ratings of the motor. In this article, we tackle this challenge via fuzzy gain scheduling proportional–integral speed controllers that have been designed by taking into account practical considerations. On the basis of experimental voltage ripple analyses conducted on the speed control loop with different system characteristics, we develop a single-input fuzzy gain scheduling proportional–integral speed controller and a double-input fuzzy gain scheduling proportional–integral speed controller to reduce the voltage ripples while providing satisfactory dynamical performance. The proposed structures continuously adjust the characteristics of the speed control loop within a specified region to exhibit different dynamical system characteristics against varying conditions. It is verified by the experimental test results that the proposed structures successfully reduced the increasing voltage ripples as the disturbances increase while providing satisfactory dynamical performance. Finally, we provided a discussion on the trade-off between the proposed structures and suggested deploying single-input fuzzy gain scheduling proportional–integral controller for micromobility speed control applications as it is agnostic to noise to a certain degree hence offering better reliability.

Generalized Differential Mathematical Model in Stator Reference Frame for PMSM and VRSM Simulation

Abstract The paper presents the deduction of a novel decoupled form (considering the differential current quantities) of the differential mathematical model in stator reference frame, useful for numeric simulation of control approaches for PMSM (permanent magnet synchronous machines) generalized for both IPMSM and SPMSM (salient and non-salient PMSM). The model is confirmed to be equivalent to the well-known model defined in the rotor synchronous reference frame using a Matlab-Simulink implementation that is verified and validated by simulation during which the power/energy conservation is monitored and the system states’ evolution is compared to the reference model in rotor reference frame using a generator structure.

Adaptive Voltage Feedback Controllers on Nonsalient Permanent Magnet Synchronous Machine

This article investigates the nonlinear behavior of the conventional voltage feedback flux-weakening control, i.e., the voltage magnitude feedback control on the nonsalient permanent magnet synchronous machine, and proposes an adaptive control parameter tuning method for the voltage feedback controller. Due to less voltage margin in the flux-weakening region, the current dynamic performance is degraded. This issue is more serious when the system operates in the overmodulation region and could affect the system's stability. Based on the designed voltage feedback controller, the system performance in the flux-weakening and overmodulation regions is further improved by utilizing the current and voltage reference modifiers. Consequently, the system can operate well in both linear and overmodulation regions with the specified scaling factor, which is beneficial to general-purpose applications. The viability of the proposed method is demonstrated by the experimental results.

Fuzzy Logic Speed Control of Permanent Magnet Synchronous Machine and Feedback Voltage Ripple Reduction in Flux-Weakening Operation Region

Voltage feedback flux-weakening control has the advantages of simplicity and robustness against parameter variation. However, due to less voltage control margin in the flux-weakening region, the increased feedback voltage ripple could deteriorate the system performance in the flux-weakening region and may even cause oscillation. In this article, based on a nonsalient permanent magnet synchronous machine, the steady-state feedback voltage ripple in the flux-weakening region are analyzed first. It shows that the feedback voltage ripple caused by the current command ripple could dominate in some flux-weakening regions. Consequently, the speed bandwidth based on the conventional speed proportional-integral (PI) controller in the flux-weakening region can be hardly increased, which leads to poor dynamic performance. In order to obtain both fast speed dynamics and less steady-state ripple, especially in the flux-weakening region, an adaptive fuzzy logic (FLC) speed controller is designed and compared with the conventional speed PI controller. With the adaptive FLC, the dc-link voltage utilization can be increased and better flux-weakening capability can be obtained. Finally, the improved performances are verified by the experimental results.

Operation Method of Non-Salient Permanent Magnet Synchronous Machine for Extended Speed Range

This paper proposes an operation method for the extended speed range of a surface-mounted permanent magnet (SPM) synchronous machine. The proposed method is based on a novel winding changeover scheme. The SPM machine has low synchronous inductance and hence poor field weakening capability. To enhance its field weakening capability, the permanent magnet's flux linkage can be reduced by performing a winding changeover. The proposed operation method increases the base speed of the machine by 3.83 times. In contrast to available two-inverter schemes with four thyristor switches, the proposed scheme utilizes a single-inverter topology drive and six bidirectional switches for the winding changeover. The machine works in two modes: cumulative and differential. In the cumulative mode, winding has a high induced back electromotive force (EMF), whereas in the differential mode, it falls by 3.54 times. The base speed increases approximately by the same ratio. After the mode switch, field weakening control is applied to the machine to further increase the speed range to 3.83 per unit. The proposed operation method was simulated in a commercial two-dimensional finite element method software in both modes under no-load and load operating conditions. The transient analysis was performed during the winding changeover, and speed range operation analysis was also carried out. The experimental results are provided to verify the extension of the speed range operation of the proposed novel winding changeover scheme for an SPM machine.

Sensorless Control of Permanent Magnet Synchronous Machine Based on Second-Order Sliding-Mode Observer With Online Resistance Estimation

In this paper, a supertwisting algorithm based second-order sliding-mode observer (STA-SMO) with online stator resistance ( $ R_{s}$ ) estimation for sensorless control of a nonsalient permanent magnet synchronous machine is proposed. A stator current observer is designed based on an STA to estimate the back electromotive force. A discontinuous sign function in the conventional SMO is replaced by a supertwisting function. The chattering problem, unavoidable in conventional SMO, is eliminated by reducing the amplitude of switching function of an STA-SMO. Meanwhile, a parallel online $ R_{s}$ estimation scheme is presented based on a modified SMO. Because mismatch between actual and set resistance may lead to estimation error and even system instability. The Lyapunov stability theorem is used to obtain the stable conditions of the proposed online $ R_{s}$ observer at both motoring and generating mode. With the help of online $ R_{s}$ observer, resistance uncertainties caused by temperature variation can be taken into account, which means robustness and stability of an STA-SMO can be improved. At the same time, higher position and speed estimation accuracy is obtained and operation range of sensorless control is extended. Finally, the proposed method is validated and compared with a conventional method by simulations and experiments.

Parameter Identification of Permanent Magnet Synchronous Machine Based on an Adaptive Mutation Dynamic Differential Evolution

The problem of parameter estimation of permanent-magnet synchronous machines (PMSMs) can be formulated as a nonlinear optimization problem. To obtain accurate machine parameters, it is necessary to develop easily applicable but efficient optimization algorithms to solve the parameter estimation models. This paper proposes a novel dynamic differential evolution with adaptive mutation operator (AMDDE) algorithm for the multiparameter simultaneous estimation of a nonsalient pole PMSM. The dynamic updating of population enables AMDDE to responds to any improved changes of the population immediately and thus generates better optimization solutions compared with the static mechanism used in original differential evolution. Two mutation strategies, namely DE/rand/1 and DE/best/1, are adaptively employed to balance the global exploration and local exploitation. The effectiveness of the proposed AMDDE is demonstrated on the multiparameter estimation for a nonsalient pole PMSM. Experimental results indicate that the proposed method significantly outperforms the existing peer algorithms in efficiency, accuracy, and robustness. Furthermore, the new algorithm can be potentially realized in digital microcontroller due to its simple structure and lower memory requirement. The proposed algorithm can also be applied to other parameter estimation and optimization problems.

Online Identification of PMSM Parameters: Parameter Identifiability and Estimator Comparative Study

In this paper, a model-reference-based online identification method is proposed to estimate permanent-magnet synchronous machine (PMSM) parameters during transients and in steady state. It is shown that all parameters are not identifiable in steady state and a selection has to be made according to the user's objectives. Then, large signal convergence of the estimated parameters is analyzed using the second method of Lyapunov and the singular perturbations theory. It is illustrated that this method may be applied with a decoupling control technique that improves convergence dynamics and overall system stability. This method is compared with an extended Kalman filter (EKF)-based online identification approach, and it is shown that, in spite of its implementation complexity with respect to the proposed method, EKF does not give better results than the proposed method. It is also shown that the use of a simple PMSM model makes estimated parameters sensitive to those supposed to be known whatever the estimator is (both the proposed method and EKF). The simulation results as well as the experimental ones, implemented on a nonsalient pole PMSM, illustrate the validity of the analytic approach and confirm the same conclusions.