Permanent Magnet Synchronous Motor Servo Research Articles

Output-Feedback Sliding Mode Control for Permanent Magnet Synchronous Motor Servo System Subject to Unmatched Disturbances

This paper aims to investigate the speed regulation problem for permanent magnet synchronous motor (PMSM) servo systems subject to unknown load torque disturbances. The proposed method utilizes sliding mode control (SMC), invariant manifold theory, and disturbance observation technique. In the PMSM servo systems, the unknown load torques will affect the control performance to a large extent, which is unmatched. In addition, compared with full-state measurement, the output-feedback framework is easy to implement and reduces the sensor costs. However, it is difficult to handle unmatched disturbance and unmeasured states simultaneously. To this end, this paper specifically combines the sliding mode control theory with the invariant manifold theory and puts forward an output-feedback disturbance rejection control method. The key idea is that the unmatched disturbance in the PMSM servo systems is transformed into matched one by taking advantage of the invariant manifold, which is different from existing results. The transformation maintains most of dynamics of the PMSM system for control design, which improves the accuracy. In addition, an extended state observer is designed to estimate the current and lumped disturbance simultaneously; then, the output-feedback SMC method is proposed by introducing the estimations. Besides, the switching gain in the proposed sliding mode controller can change with estimation errors adaptively, and the chattering reduces. Simulation results on a PMSM system validate the effectiveness of the proposed control strategy.

Finite-time adaptive NN control for permanent magnet synchronous motors with full-state constraints

This paper proposes a finite-time adaptive neural network (NN) position tracking control method for the permanent magnet synchronous motor (PM SM) servo system with full-state constraints. NNs are utilized to compensate the parameter uncertainties and load torque disturbances of the PMSM servo system. Multiple barrier Lyapunov functions are introduced in the backstepping based control design, such that the rotor position, the rotor angular velocity and the currents of the d-q axis are constrained in given compact sets. In addition, the finite-time control technique is adopted to the control design, which can accelerate the convergence speed and improve the robustness of the PMSM servo system. Under the proposed control algorithm, the position tracking control is realized in finite time, and the tracking error can converge to a small neighborhood of the origin. Finally, simulation results are presented to show the effectiveness of the developed control approach, and some comparisons are given to show the rapid and accurate position tracking control performance.

Investigation on the Effect of Dead Time on the Phase of Fundamental Voltage in VSI-PMSM Drive System

Both electric vehicle PMSM drive system and grid connected photovoltaic (PV) power generation need voltage source inverter (VSI). The dead time should be set properly when the power switches are turned on and off in the same bridge arm of VSI. During the dead time, the load is out of control, which will cause the abnormal output voltage amplitude and phase. However the influence of dead time on the output fundamental voltage phase has not been paid much attention to and studied. Firstly, in the paper, the phase shift of output fundamental voltage caused by dead time is simulated and analyzed for three-phase VSI - resistance inductance series (RL) load system under several conditions such as variable switching frequency, modulation index, output fundamental frequency and dead time. Secondly, take three-phase VSI - permanent magnet synchronous motor (PMSM) drive system for instance, the simulation analysis of output fundamental voltage phase shift and rotor positioning error caused by dead time are also performed, and an off-line method to compensate the fundamental voltage phase based on αβ coordinate is given. The above work provides a reference for further understanding the influence of dead time on fundamental voltage phase shift in VSI, so as to improve the monitoring and control precision of electric vehicle drive system. The analysis approach can be applicable to the grid connected photovoltaic (PV) power generation PMSM servo system.

A Two-Degree-of-Freedom Controller Design Satisfying Separation Principle With Fractional-Order PD and Generalized ESO

This article proposes a two-degree-of-freedom fractional-order proportional derivative (FOPD) controller with a general extended state observer (GESO) to achieve both optimal set-speed tracking and disturbance rejection performance for a typical permanent magnet synchronous motor servo system. The GESO simplifies the control plant, estimates and actively rejects total disturbances. The FOPD controller achieves fast speed tracking with almost no overshoot. Furthermore, it is verified that the control system with the proposed FOPD-GESO controller design meets the separation principle through mathematical derivation and simulation illustration. It shows that the proposed controller breaks the inherent tradeoff on tracking performance and disturbance robustness of the typical traditional proportional–integral–derivative (PID) control. Meanwhile, a systematic scheme for designing the FOPD-GESO controller to satisfy both frequency-domain and time-domain specifications is proposed in this article. Simulation illustration and experimental validation are performed to demonstrate that the proposed FOPD-GESO controller is superior to the typical integer-order PID controller, integer-order active disturbance rejection control with a typical extended state observer, and fractional-order PID controller in terms of speed tracking, antiload disturbance, and robustness to internal uncertainties.

Research on fuzzy control of permanent magnet synchronous motor for a mobile robot

In this paper, a biped robot powered by permanent magnet synchronous motor (PMSM) is proposed, and each leg of the robot is a 6-degrees of freedom (DOF) parallel mechanism. Due to highly nonlinear characteristics of the leg structure, the conventional PID control strategy based on trial-error process cannot maintain the high performance of the PMSM. In order to improve the robustness of PMSM servo system and the dynamic stability of the robot, the PID controller based on fuzzy theory is developed. Fuzzy PID controller can improve the tracking accuracy and load rejection capability of PMSM, which makes the real-time system response faster without overshoot. The simulation results show that compared with conventional PID, fuzzy PID can reduce position tracking error of PMSM and deal with the external disturbance effectively.

Real-time dc-link voltage control of 5-kW PMSG-based wind turbine generator through a test-rig

In this work unlike the usual grid side converter, the machine side converter is considered to control the dc-link voltage of a permanent magnet synchronous generator-based wind turbine generator. For this purpose, a discrete real-time laboratory test-rig is prepared for real-time application of the system. In the real-time test-rig, 5-kVA permanent magnet synchronous servo motor is driven by Unidrive SP variable frequency drive to emulate a standalone wind energy conversion system; GUASCH converter as a machine side converter and for implementing the designed PI controllers using pole placement technique combined with a symmetrical optimum criterion for real-time control of the dc-link voltage transient changes, Texas instrument TMS320F28069 digital signal processor discrete real-time microcontroller control card in a GUASCH board are used. Moreover, a simulation model of the system is prepared in MATLAB Simulink user-defined function blocks considering the dynamic mathematical equations of every part in the system. Achieved simulation and real-time test-rig results show that the designed dc-link voltage control of the system works properly at different transient load changes connected to the standalone WTG and dc voltage reference value changes. Moreover, the simulation results are properly validated by the real-time test-rig results and the PI controller designed using pole placement technique combined with a symmetrical optimum criterion method was ideal.

Trajectory Tracking and Vibration Control of Flexible Beams in Multi-Axis System

In this paper, an X-Y position stage simulates flexible loads completing handling or detection tasks in industrial applications are studied. The platform is driven by permanent magnet synchronous motors (PMSM) servo system, which has flexible beams with different natural vibration frequencies on the X-axis and Y-axis. The controller is designed to suppress the vibration of the flexible beams with different frequencies and reducing the contour error. The Euler-Bernoulli beam theory is adopted to obtain the mode shapes and natural frequencies of the flexible beam with clamped and endpoint mass boundary conditions. Analysis shows that the first-order vibration mode contributes the most to the displacement of the flexible beam. The trajectory motion profile based on time-shifted cosine jerk central angle interpolation (CJCI) contains prefilter to suppress low vibration frequencies in the two beams, which does not cause distortion of the actual contour. The linear phase lead iterative learning control (ILC) combined with the contour of CJCI is proposed to reduce the tracking errors of each axis, thereby reducing the overall contour error. The analysis and design process of ILC in frequency domains, which is applied to alleviate noise and disturbance effects. Comparison experiments confirm the effectiveness of the proposed method.

Synthesis of fractional order robust controller based on Bode’s ideas

The basic Bode’s ideal transfer function (BITF) based controller may not guarantee sufficient disturbance rejection for a class of plants with a cascaded integrator. In this paper, an improved BITF based control method is proposed to enhance the disturbance rejection performance for this class of control systems. A fractional order proportional–integral controller and a Bode’s ideal cut-off filter are introduced into the BITF based control strategy, improving the open-loop magnitude characteristics of the control system in the low and high frequency ranges. Therefore, the disturbance rejection performance of the control system can be improved, with small impact on the system’s stability. The improved BITF based control method is applied to the speed control problem of a class of permanent magnet synchronous motor servo systems. The robustness and dynamic response performances of the improved BITF based control system are verified by simulation and experiments. Performance comparisons are performed between the system using the improved BITF based control method and those using some existing control methods. Simulation and experimental results both show that the improved BITF based controller can enhance the step response performance and robustness of the PMSM servo system simultaneously and make the system achieve better disturbance rejection performance than the systems using some existing methods.

An adaptive PID-type sliding mode learning compensation of torque ripple in PMSM position servo systems towards energy efficiency

In this paper, for periodic motion tasks, combining adaptive PID-type sliding mode control (APIDSMC), model reference adaptive control (MRAC) and periodic adaptive learning control (PALC), a novel APIDSMC-PALC compensation approach towards energy efficiency is proposed to suppress the influence of torque ripple in permanent magnet synchronous motor (PMSM) servo systems. Using particle swarm optimization (PSO) algorithm, the equivalent control gain of sliding mode control is optimized to achieve energy efficiency during long-term operation. The objective of the proposed ripple compensation algorithm is to accurately approximate two dominant harmonic amplitudes in the torque ripple and generate an additional control effort for ripple compensation. Simulation and testbed experimental results demonstrate that with the proposed ripple compensation algorithm, the objective of excellent position tracking performance is ensured, and the energy efficiency is improved.

Detection of mechanical resonance frequencies for interior permanent magnet synchronous motor servo drives based on wavelet multiresolution filter

To realise the resonant characteristics of motor drive system, a wavelet multiresolution filter (WMF)-based scheme is proposed in this study to perform the detection of the mechanical resonant frequencies for interior permanent magnet synchronous motor servo drives. In a conventional motor drive system, the compliance in the coupling between motor and load may cause resonance. Moreover, the parasitic torque ripples resulting from the harmonics of a pulse-width modulation inverter may excite mechanical vibrations. In the proposed scheme, the localisation analysis of signal can be completed with the WMF at any time and frequency domains for the extraction of resonant frequencies. Then, a band-pass filter is applied to perform the frequency sweeping for the detection of resonant frequencies. In the final stage, the signal smoothing is implemented with the calculation of absolute and average values. To verify the effectiveness of the proposed resonant-frequency detection scheme using the WMF, some experimental results at different rotor speed and load conditions are provided. In addition, a two-channel dynamic signal analyser is also adopted in the experimentation for the comparison of resonant-frequency detection.

Deep reinforcement learning for permanent magnet synchronous motor speed control systems

The permanent magnet synchronous motor (PMSM) servo system is widely applied in many industrial fields due to its unique advantages. In this paper, we study the deep reinforcement learning (DRL) speed control strategy for PMSM servo system, in which exist many disturbances, i.e., load torque and rotational inertia variations. The speed control problem is formulated as a Markov decision process problem, which is computed optimal regulation scheme corresponding to each speed and error state using the deep Q-networks. Simulation results are provided to demonstrate that compared with conventional proportion integral control, the proposed DRL control can improve the robustness against load disturbances and high performance of the PMSM speed control system.

Rotor Position Tracking Control for Low Speed Operation of Direct-Drive PMSM Servo System

In this article, a rotor position tracking control (RPTC) strategy is proposed to effectively reduce the speed fluctuation for a direct-drive permanent magnet synchronous motor servo system operating at a low speed with different torque disturbances. In this article, considering the derivative relationship between the rotor position and speed, a speed command is converted to a real-time rotor position trajectory, and then a position-current two-loop control with the RPTC controller is proposed based on the internal model method to smoothly track the rotor position. In addition, the parameter design of the RPTC controller from the perspectives of robust stability and antidisturbance capability is investigated as well. The comparative simulation and experimental results demonstrate that, at a low speed, the proposed RPTC strategy has a good speed performance for both periodic and nonperiodic torque disturbances. Moreover, it enjoys a simple implementation for not requiring the precise speed feedback and specific torque disturbance information.

Implementation of integral fixed-time sliding mode controller for speed regulation of PMSM servo system

Aiming at the control problem for the speed regulation system of permanent magnet synchronous motor (PMSM), an integral fixed-time sliding mode control algorithm with the disturbance estimation compensation is designed to improve PMSM system’s disturbance rejection ability in this paper. First of all, the integral fixed-time sliding mode surface is selected according to the error dynamical equation. Then an integral fixed-time sliding mode control algorithm is proposed and rigorous analysis method of the Lyapunov function is provided to demonstrate the speed tracking error will converge to zero in a fixed time. Besides, considering the effect of disturbance load torque, an integral fixed-time sliding mode control algorithm with disturbance estimation compensation is proposed. Through disturbance feedforward compensation, the integral fixed-time sliding mode control law can offer a better dynamical performance with smaller value for the speed chattering. Finally, comparison results of numerical experiments are provided to verify the effectiveness and superiority of the integral fixed-time sliding mode control method.

Adaptive Repetitive Learning Control of PMSM Servo Systems with Bounded Nonparametric Uncertainties: Theory and Experiments

In this article, an adaptive repetitive learning control (ARLC) scheme is proposed for permanent magnet synchronous motor (PMSM) servo systems with bounded nonparametric uncertainties, which are divided into two separated parts. The periodically nonparametric part is involved in an unknown desired control input, and a fully saturated repetitive learning law with a continuous switching function is developed to ensure that the estimate of the unknown desired control input is continuous and confined with a prespecified region. The nonperiodically nonparametric part is transformed into the parametric form and compensated by designing the adaptive updating laws, such that a prior knowledge on the bounds of uncertainties is not required in the controller design. With the proposed ARLC scheme, a high steady-state tracking accuracy is guaranteed, and comparative experiments are provided to demonstrate the effectiveness and superiority of the proposed method.

A fast integral sliding mode controller with an extended state observer for position control of permanent magnet synchronous motor servo systems

Permanent magnet synchronous motor (PMSM) has been widely used in position control applications. Its performance is not satisfactory due to internal uncertainties and external load disturbances. To enhance the control performance of PMSM systems, a new method that has fast response and good robustness is proposed in this study. First, a modified integral terminal sliding mode controller is developed, which has a fast-sliding surface and a continuous reaching law. Then, an extended state observer is applied to measure the internal and external disturbances. Therefore, the disturbances can be compensated for in a feedforward manner. Compared with other sliding mode methods, the proposed method has faster response and better robustness against system disturbances. In addition, the position tracking error can converge to zero in a finite time. Simulation and experimental results reveal that the proposed control method has fast response and good robustness, and enables high-precision control.

Robust Two-degree-of-freedom Control Based on H∞ Method for PMSM Drive System

Background: The conventional method using one-degree-of-freedom (1DOF) controller for Permanent Magnet Synchronous Motor (PMSM) servo system has the trade-off problem between the dynamic performance and the robustness. Methods: In this paper, by using H∞ control theory, a novel robust two-degree-of-freedom (2DOF) controller has been proposed to improve the position control performance of PMSM servo system. Using robust control theory and 2DOF control theory, a H∞ robust position controller has been designed and discussed in detail. Results: The trade-off problem between the dynamic performance and robustness which exists in one-degree-of-freedom (1DOF) control can be dealt with by the application of 2DOF control theory. Then, through H∞ control theory, the design of robust position controller can be translated to H∞ robust standard design problem. Moreover, the control system with robust controller has been proved to be stable. Conclusion: Further simulation results demonstrate that compared with the conventional PID control, the designed control system has better robustness and attenuation to the disturbance of load impact.

Active disturbance rejection position servo control of PMSLM based on reduced-order extended state observer

To enhance the control accuracy of permanent magnet synchronous linear motor (PMSLM) servo systems affected by disturbances, such as time-varying parameters and abrupt load changes, an active disturbance rejection control (ADRC) algorithm based on a reduced-order extended state observer (ESO) is adopted to suppress the disturbances on the control system. First, the system's ability to estimate disturbances is enhanced by linearizing the ESO. Second, the pole placement method is used for the construction of a reduced-order ESO that can reduce the influence of the number of adjustment parameters and the phase lag. The parameters of the reduced-order ADRC are adjusted, the optimal control parameters are selected, and the stability of controller is proved. Finally, practical experiments prove that the proposed method can improve control accuracy under multiple working conditions and features strong anti-interference ability. There is a smaller steady-state error, and no overshoot is observed.

Torque Ripple Suppression of Permanent Magnet Synchronous Motor Based On Robust Current Injection

In order to improve the performance of permanent magnet synchronous motor (PMSM) servo system and suppress the influence of torque ripple on the control system, a robust current injection control method combining active disturbance rejection controller (ADRC) and current injection is proposed. We designed a current injection module to suppress the torque ripple of the motor and proposed an ADRC to improve the anti-disturbance performance of the system, which ensures the strong robustness and rapidity of the system. The simulation results show that compared with the conventional PI control and PI superimposed current injection, the proposed method can more effectively suppress the torque ripple, while improving the robustness and dynamic response of the system.

Online Autotuning Technique for IPMSM Servo Drive by Intelligent Identification of Moment of Inertia

In this article, a real-time moment of inertia identification technique using Petri probabilistic fuzzy neural network with an asymmetric membership function (PPFNN-AMF) for an interior permanent magnet synchronous motor (IPMSM) servo drive is proposed. The estimated moment of inertia will be used in the online design of an integral–proportional (IP) speed controller to achieve the gains autotuning of the IPMSM servo drive. In the proposed method, the dynamic analysis of a field-oriented control IPMSM servo drive system with an IP speed controller is constructed first. Then, a heuristic approach using the PPFNN-AMF is proposed for the real-time identification of the moment of inertia of the IPMSM servo drive system. Moreover, the network structure and the convergence analysis of the PPFNN-AMF are devised and derivated. Furthermore, an IPMSM servo drive based on a high-performance digital signal processor is developed. Finally, from the experimental results, the gains of the IP speed controller can be tuned online effectively at different operating conditions with robust control characteristics.

Practical interval type-2 fuzzy self-tuning of PID controller to servo permanent magnet synchronous motor

This paper implements a practical interval type-2 fuzzy self-tuning (IT2FST) of optimal PID (OPID) controller to servo permanent magnet synchronous motor (SPMSM). The proposed method IT2FST updates the OPID controller gains in an online manner to drive the SPMSM with better speed response during variable load and parameter uncertainty occurrence. In this work, the industrial SPMSM system comprises three-phase PMSM with internal break, drive and mechanical parts. Due to the incomplete real information of the SPMSM, nonlinear least square algorithm has been utilized for its model identification. A comparative analysis in a real time of the SPMSM with an OPID, type-1 fuzzy self-tuning and IT2FST for OPID controllers under the influence of parameter uncertainties and external load disturbances has been carried out. The real-time practical implementation results illustrated that the proposed IT2FST of OPID controller gives a simple opportunity to enhance the speed performance of the SPMSM than the other controllers.