Traditional Sliding Mode Observer Research Articles

Research on an Improved Sliding Mode Observer for Speed Estimation in Permanent Magnet Synchronous Motor

Aimed at the problems of system chattering and large observation errors in the sensorless control of a permanent magnet synchronous motor (PMSM) based on a traditional sliding mode observer (SMO), a combined reaching law algorithm based on the exponential reaching law and arcsine saturation function reaching law is proposed to improve the sliding mode observer. An appropriate positive real number is taken and compared with the product of controller gain and stator current observation error to judge the system position in sliding mode motion. In the early stage of sliding mode motion, the exponential reaching law is utilized, and then, in the latter and stable stages of sliding mode motion, the arcsine saturation function reaching law is used. The stability of the observer is proved by Lyapunov theory. The simulation and experimental data show that the speed error of the sliding mode observer based on the combined reaching law is reduced by 80% compared with the traditional sliding mode observer, and the chattering problem is also improved.

ADRC Control System of PMLSM Based on Novel Non-Singular Terminal Sliding Mode Observer

In an attempt to solve the problem of the many parameters of the traditional active disturbance rejection controller (ADRC) and to accurately estimate the mover position and speed required by a permanent magnet synchronous linear motor (PMLSM) system, an improved ADRC and a novel nonsingular fast terminal sliding mode observer (NFTSMO) are proposed. Firstly, the traditional first-order ADRC is simplified, the tracking differentiator (TD) module is removed, and the direct error is used to replace the nonlinear function in the extended state observer (ESO) and nonlinear state error feedback (NLSEF) module. Based on the traditional NFTSMO, the smooth back electromotive force (EMF) is obtained by adding the TD to reduce the phase delay caused by the low-pass filter in the traditional sliding mode observer (SMO), and the actuator position and speed information are modulated from the observed back EMF based on the principle of a phase-locked loop (PLL). Simulation and experiments show that this method not only simplifies the system structure of PMLSM but also optimizes many parameters in ADRC while retaining the original excellent performance. Compared with the traditional NFTSMO, the improved NFTSMO enhances the observation accuracy, reduces the chattering phenomenon of the system, and improves the robustness of the system.

Reliable control strategy based on sliding mode observer against FDI attacks in smart grid

AbstractThis paper is concerned with the reliable operation of cyber‐physical systems under false data injection attacks. First of all, a robust adaptive sliding mode observer is designed to estimate the state of the power system; different from the traditional sliding mode observer, the observer we designed is not only robust to state errors but also can automatically adjust the parameter of attack identification. Secondly, a method of attack reconstruction has been given to estimate the actual attack signal. Finally, a reliable sliding mode control strategy is proposed to eliminate the impact of false data injection attacks; compared with the existing results, the designed defense strategy utilizes the reconstructed attack signal in the attack identification scheme and state error signal at the same time. Moreover, a power system with 3 generator buses and 6 load buses is taken as an simulation example to verify the availability of the proposed control strategy.

SPMSM Sensorless Control System Based on ASMO

Aiming at the chattering problem of traditional sliding mode observer (SMO) in surface-mounted permanent magnet synchronous motor (SPMSM) control system when estimating rotor position and speed and adaptive sliding mode observer (ASMO) is designed in this paper. The observer can reduce chattering and avoid the introduction of the low-pass filter, which simplifies the system structure, considering the difficulty in determining the sliding mode gain of the existing sliding mode observer, and an adaptive law is designed to adjust the sliding mode gain with the change of the back electromotive force, to meet the operation requirements of the system and improve the control accuracy of the sensorless control system. Finally, the simulation is built through Matlab/Simulink platform. It is proved that the proposed control strategy can satisfy the system’s accuracy and simultaneously reduce the chattering and solve the problem that the gain is difficult to determine.

Position sensorless control of PMLSM based on adaptive complex coefficient sliding mode observer

In order to suppress the problems of chattering, harmonic and three phase electromotive force unbalance of sliding mode observer in the sensorless control of permanent magnet linear synchronous motor, an improved sliding mode observer is studied in this paper. These negative disadvantages can be addressed by adaptive complex coefficient filters with band pass and positive and negative sequence frequency selection characteristics. Therefore, the low pass filter of traditional sliding mode observer is replaced by adaptive complex coefficient filter in this paper.Meanwhile, the nonlinear saturation function is used instead of the symbolic function to reduce the chattering of the sliding mode observer. The experimental results show that the presented algorithm can improve the speed and position observation accuracy of the sliding mode observer.

SMO-Based Sensorless Control of a Permanent Magnet Synchronous Motor

In order to reduce the chattering caused by the discontinuity of the control function in the traditional sliding mode observer (SMO), this article proposes a sliding mode observer with phase-locked loop (PLL) to estimate the speed and position of the rotor. The back electromotive force (EMF) of a permanent magnet synchronous motor (PMSM) in a static coordinate system is accurately estimated by SMO, and then, PLL is constructed to combine the observed rotor position angle and back EMF to compensate the phase lag in angle estimation so as to obtain a more accurate speed. It solves the problems of poor robustness and complex algorithms in the traditional SMO prediction algorithm. The simulation results show that the SMO with PLL can effectively reduce the system chattering and effectively improve the accuracy of rotor speed and position estimation.

Adaptive Fuzzy Observer-Based Fault Estimation for a Class of Nonlinear Stochastic Hybrid Systems

This article studies the fault estimation problem for a class of continuous-time nonlinear Markovian jump systems with unmeasured states, unknown bounded sensor faults, and unknown nonlinearities simultaneously. In this article, a new adaptive fuzzy observer design scheme is developed, where the completely unknown nonlinear terms are approximated by adaptive fuzzy logic systems. By means of a novel online adaptive mechanism, the asymptotic stability of the error dynamic system is guaranteed despite of sensor faults and unknown nonlinear terms. Moreover, the sliding surface switching problem in the traditional sliding mode observer techniques can be avoided for Markovian jump systems. Finally, two practical examples are given to demonstrate the effectiveness of the proposed approach.

A New Type of Sliding Mode Observer for Permanent Magnet Synchronous Motor Control

Aiming at the high-frequency oscillation and estimation accuracy problems of traditional sliding mode observers in the control process of permanent magnet synchronous motors, a sensorless control method for permanent magnet synchronous motors based on a new approaching law sliding mode observer is proposed. Based on the construction of a permanent magnet synchronous motor two-phase static coordinate system model, a sliding mode observer is used to estimate the back electromotive force, and then the rotor speed and position information are obtained. Finally, a simulation experiment is carried out. The results show that the new sliding mode observer based on the new approaching law effectively reduces the high frequency chattering of the system, improves the estimation accuracy of the system, and has better control performance.

Fuzzy adaptive super‐twisting algorithm based sliding‐mode observer for sensorless control of permanent magnet synchronous motor

Aiming at the issues of slow convergence, phase delay, and chattering in the sensorless vector control system of permanent magnet synchronous motor (PMSM) controlled by sliding mode observer (SMO), a fuzzy adaptive super-twisting (ST) SMO sensorless control algorithm is proposed. The fuzzy adaptive algorithm is used to estimate the uncertain boundary and adaptively adjust sliding mode gain, which is used in the ST algorithm to accelerate the convergence speed of sliding mode gain, and eliminate the system delay caused by phase locked loop and phase compensation, and improve the estimation accuracy of speed and rotor position. In this algorithm, the sigmoid function is used instead of the signum function in the traditional SMO to suppress system chattering. Lyapunov stability theorem is used to obtain the stable conditions of position and speed observer at motoring mode. The saturated ST-SMO algorithm is verified by Matlab/Simulink. The simulation results show that compared with the traditional SMO, the fuzzy ST-SMO algorithm proposed in this paper has faster convergence speed in the variable speed and the variable load of PMSM sensorless control system, which has significantly reduced chattering, obtained more accurate speed and rotor position and has better dynamic response and robustness.

Sensorless Control of Vehicle-mounted PMSM Based on Improved Sliding Mode Observer

In order to solve the chattering and phase delay problems in the traditional sliding mode observer(SMO), this paper proposes an improved sliding mode observer, which effectively weakens the chattering by using a new piecewise function as the switching function. At the same time, angle compensation is provided for the phase delay caused by the introduction of a low-pass filter, and then the arctangent function is used to extract the rotor position and speed information of the PMSM. Compared with the traditional sliding mode observer, from the simulation results, we can see that the improved control system has obvious advantages in reducing chattering, improving convergence speed, and improving speed estimation accuracy.

Study on six‐phase PMSM control strategy based on improved position sensorless detection technology

The six-phase motor control system has low torque ripple, low harmonic content, and high reliability; therefore, it is suitable for electric vehicles, aerospace and other applications requiring high power output and reliability. This study presents a superior sensorless control system for a six-phase permanent magnet synchronous motor (PMSM). The mathematical model of PMSM in stationary coordinate system is presented; its sliding mode observer (SMO) of back electromotive force (BEMF) acquires the motor speed and position information. As torque ripple and harmonic components affect the BEMF estimated value through the traditional SMO, the function of the frequency-variable tracker of the stator current (FVTSC) is used instead of the traditional switching function. By improving the SMO method, the BEMF is estimated independently, and its precision is maintained under startup or variable-speed states. To improve performance of the system, the auto disturbance rejection controller (ADRC) is used to suppress load disturbance and speed overshoot. To reduce model parameters, an ADRC with sliding mode algorithm is proposed, simplifying the structure and simultaneously solving the parameter tuning problem. Finally, comparing the ADRC with FVTSC SMO and the traditional PI controller shows that the new ADRC effectively improves the dynamic and static performance of the PMSM.

Speed sensorless control of a bearingless induction motor based on sliding mode observer and phase-locked loop

To realize the low-cost and high-performance of a bearingless induction motor (BIM), a speed sensorless control strategy combined with the improved sliding mode observer (SMO) and phase locked-loop (PLL) is proposed. Based on analyzing the principle of the traditional SMO, the improved SMO adopts a switching function that has a double boundary layer structure to reduce the high-frequency jitter. Firstly, the observation equation of the rotor flux is established where the stator current, as well as the rotor flux are two state variables, and then the system stability is discussed with the Lyapunov theory. Secondly, to reduce the rotor chatter and enhance the speed tracking performance a flux electrical angle detecting module is constructed based on the PLL structure that extracts the rotor flux electrical angle and speed from the observed flux component. Finally, the BIM speed sensorless vector control system is established and the simulation results and experimental results are respectively presented by the MATLAB/Simulink simulation platform and a laboratory prototype. Both results prove that this strategy can not only enhance the speed self-detection capability and tracking performance, but can guarantee the excellent self-suspension function as well.

Research on an Improved Sliding Mode Sensorless Six-Phase PMSM Control Strategy Based on ESO

The six-phase motor control system has low torque ripple, low harmonic content, and high reliability; therefore, it is suitable for electric vehicles, aerospace, and other applications requiring high power output and reliability. This study presents a superior sensorless control system for a six-phase permanent magnet synchronous motor (PMSM). The mathematical model of a PMSM in a stationary coordinate system is presented. The information of motor speed and position is obtained by using a sliding mode observer (SMO). As torque ripple and harmonic components affect the back electromotive force (BEMF) estimated value through the traditional SMO, the function of the frequency-variable tracker of the stator current (FVTSC) is used instead of the traditional switching function. By improving the SMO method, the BEMF is estimated independently, and its precision is maintained under startup or variable-speed states. In order to improve the estimation accuracy and resistance ability of the observer, the rotor position error was taken as the disturbance term, and the third-order extended state observer (ESO) was constructed to estimate the rotational speed and rotor position through the motor mechanical motion equation. Finally, the effectiveness of the method is verified by simulation and experiment results. The proposed control strategy can effectively improve the dynamic and static performance of PMSM.

Sensorless Control Strategy of a Permanent Magnet Synchronous Motor Based on an Improved Sliding Mode Observer

This paper analyzes the problems and the reasons of high frequency chattering, phase delay, unmanageable with low-speed rotation in the traditional SMO control strategy of the sensor-less control strategy of a permanent magnet synchronous motor based on the traditional sliding mode observer. Aiming at the shortcomings of the above-mentioned traditional SMO control strategy, an improved SMO control strategy is presented by replacing the signum function in the traditional synovial observer with the sigmoid function to reduce the high frequency chattering of the system. Meanwhile, the proposed improved SMO control strategy introduces an adaptive filter to eliminate harmonics and chattering, and adaptively compensates the estimated back-EMF value to reduce the estimation error caused by the phase delay. The improved SMO strategy was tested through Matlab/Simulink simulation and real experiments respectively. The results verified that the improved SMO strategy can significantly reduce chattering and phase delay and achieve good control performance at low speeds, as well as maintain good performance at full speed.

Research about the Sensorless Vector Control of Permanent Magnet Synchronous Motor Based on Two-stage Filter Sliding Mode Observer

In order to overcome the disadvantages of installing mechanical sensors and the problems of chattering and low observation accuracy in traditional sliding mode observer sensorless control, a two-stage filter Sliding Mode Observer (SMO) is proposed in this paper. By collecting the current and voltage of the Permanent Magnet Synchronous Motor (PMSM), the SMO algorithm is realized by using the state equation of the motor in the synchronous stationary coordinate system; the position of the rotor is estimated by the arc tangent function, the observation accuracy of the rotor position is improved by increasing phase compensation; the variable cut-off frequency filter is introduced to make the Low Pass Filter (LPF) cut-off frequency can be self-adjusted with the change of rotational speed, which improves the estimation accuracy of rotor position at different rotational speeds. Kalman filter is introduced to form a two-stage filter with variable cut-off frequency LPF, which greatly weakens the chattering of the motor and reduces the observation error. Finally, the simulation is carried out under MATLAB/Simulink. The simulation results show that the PMSM vector control system with two-stage filter sliding mode observer has high estimation accuracy, good dynamic and steady-state performance, strong anti-jamming ability and robustness.

Speed Sensor‐Less Control System of Surface‐Mounted Permanent Magnet Synchronous Motor Based on Adaptive Feedback Gain Supertwisting Sliding Mode Observer

Aiming at the problems of severe chattering and difficulty in low‐speed operation of the surface‐mounted permanent magnet synchronous motor (SPMSM) sensor‐less speed control system based on the traditional sliding mode observer (SMO), this paper proposes a sensor‐less control strategy of supertwisting sliding mode observer based on adaptive feedback gain (AFG‐STA‐SMO). This strategy combines the supertwisting algorithm (STA) with the equivalent feedback principle and designs an adaptive law to compensate for the rotor position error by adjusting the feedback gain coefficient online. Secondly, considering the ripple component in the back electromotive force (back‐EMF), the Kalman filter gets a smoother back‐EMF signal, further improving the rotor position estimation accuracy. The stability of the system is proved by using the Lyapunov function. Finally, the feasibility and effectiveness of the proposed control strategy are verified by MATLAB/Simulink simulation.

New Sensorless Vector Control System With High Load Capacity Based on Improved SMO and Improved FOO

In the existing sensorless vector control system of permanent magnet synchronous motor (PMSM), direct differential calculation or phase-locked loop (PLL) control is often used to estimate the rotor speed, but this method has some problems of weak load capacity and slow dynamic response. A new sensorless vector control method based on an improved sliding mode observer (SMO) and improved full-order observer (FOO) is proposed in this paper. The cut-off frequency of the low-pass filter is designed as a function of speed, the back EMF is fed back into the stator current estimation mathematical model, and the adaptive rate of feedback gains coefficient is proposed for improving the traditional SMO. The disturbance feedback matrix is introduced for improving the traditional FOO, and the estimated load torque is feedforward compensated to the given end of the quadrature current. An integrated system of corresponding algorithms is established, a test platform is built. The experimental results show that the speed and load torque estimation performance of the improved observer is better than that of the traditional observer in the process of sudden load change. The sensorless vector control system based on the proposed observer has a high dynamic response, load capacity, and reliability.

Full-Order Sliding Mode Observer Based on Synchronous Frequency Tracking Filter for High-Speed Interior PMSM Sensorless Drives

In the research of the high-speed sensorless control strategy of an interior permanent-magnet synchronous motor (IPMSM), considering the harmonic influence of inverter nonlinearity on traditional sliding mode observer method, a full-order sliding mode observer (SMO) method based on synchronous frequency tracking filtering is proposed. This method avoids the phase delay defects caused by the use of filters in traditional second-order SMO. Then, the observed extended electromotive force (EMF) signal is filtered using a synchronous frequency tracking (SFT) function. It tracks the changing stator current and filters out harmonics that are not part of the tracking signal to achieve static tracking of the stator current. Then, the rotor speed can be estimated by a Luenberger-based observer. Experimental results verify the effectiveness and feasibility of the proposed method.

Rotor-current-based fault detection for doubly-fed induction generator using new sliding mode observer

To detect the fault of the doubly-fed induction generator (DFIG), in this paper, a fault detection method of novel sliding mode observer is proposed, without a velocity sensor. In addition to better elimination of chattering for the new sliding mode observer, at the same time, it has better stability and faster convergence speed than the traditional sliding mode observer. Firstly, the sliding mode observer is built according to the mathematical model of the DFIG. Then, the rotor current and the rotational speed are estimated. After comparing the actual rotor current value with the observed value, the self-detection of the fault for the DFIG is realized. Secondly, three faults of grid voltage sags failure, DFIG inter-turn stator fault and rotor current sensor fault are given respectively. After that the Simulink simulation model is built under different fault conditions. It is proved by simulation that this sliding mode observer can well detect faults occurring at different positions. Additionally, it can also be proved that the sliding mode observer has the characteristics of fast response and good stability.

Research on Sensorless Control System of PMSM Based on Adaptive Fuzzy Sliding Mode Observer

The vector control system of permanent magnet synchronous motor needs to use encoder and other speed measuring devices, which will increase the cost of the system and bring reliability problems. In order to solve these problems, this paper proposes a sensorless control system of PMSM Based on adaptive fuzzy sliding mode observer. Firstly, in order to suppress the chattering problem of the traditional sliding mode observer, the continuous sigmoid function is used as the switching function of the sliding mode observer to improve the stability of the system. Then, the adverse effect of the fixed sliding mode gain on the system performance is analysed. Observer Combined with the fuzzy control theory, the error function is selected as the fuzzy input, the fuzzy rules are formulated, and the fuzzy controller is designed to adjust the sliding-mode gain adaptively. Finally, the simulation model of sensorless control system of PMSM is established. The simulation results verify the feasibility of the proposed scheme.