Sensorless Control System Research Articles

A Sensorless Control System for an Implantable Heart Pump Using a Real-Time Deep Convolutional Neural Network.

Left ventricular assist devices (LVADs) are mechanical pumps, which can be used to support heart failure (HF) patients as bridge to transplant and destination therapy. To automatically adjust the LVAD speed, a physiological control system needs to be designed to respond to variations of patient hemodynamics across a variety of clinical scenarios. These control systems require pressure feedback signals from the cardiovascular system. However, there are no suitable long-term implantable sensors available. In this study, a novel real-time deep convolutional neural network (CNN) for estimation of preload based on the LVAD flow was proposed. A new sensorless adaptive physiological control system for an LVAD pump was developed using the full dynamic form of model free adaptive control (FFDL-MFAC) and the proposed preload estimator to maintain the patient conditions in safe physiological ranges. The CNN model for preload estimation was trained and evaluated through 10-fold cross validation on 100 different patient conditions and the proposed sensorless control system was assessed on a new testing set of 30 different patient conditions across six different patient scenarios. The proposed preload estimator was extremely accurate with a correlation coefficient of 0.97, root mean squared error of 0.84 mmHg, reproducibility coefficient of 1.56 mmHg, coefficient of variation of 14.44%, and bias of 0.29 mmHg for the testing dataset. The results also indicate that the proposed sensorless physiological controller works similarly to the preload-based physiological control system for LVAD using measured preload to prevent ventricular suction and pulmonary congestion. This study shows that the LVADs can respond appropriately to changing patient states and physiological demands without the need for additional pressure or flow measurements.

Speed sensorless control of permanent magnet synchronous motor based on robust adaptive algorithm

In order to solve the problem that the parameters of the regulator and the actual parameters do not match due to the time-varying motor parameters in the operation of PMSM, this paper adopts a robust adaptive control strategy based on linear matrix inequality (LMI) based on the model reference adaptive method (MRAS) to consider the uncertainties of the motor parameters in the state equation of the motor control system, the controller parameters are obtained by solving the LMI. The simulation model of PMSM speed sensorless control system is built in Simulink. The simulation results show that the system can track the given speed well and has strong robustness when the motor parameters change.

Sensorless Control of Bearingless Permanent Magnet Synchronous Motor Based on LS-SVM Inverse System

In order to solve the problems of low integration, low reliability, and high cost caused by mechanical sensors used in bearingless permanent magnet synchronous motor (BPMSM) control systems, a novel speed and displacement sensorless control method using a least-squares support vector machine (LS-SVM) left inverse system is proposed in this paper. Firstly, the suspension force generation principle of the BPMSM is introduced, and the mathematical model of the BPMSM is derived. Secondly, the observation principle of the left inverse system is explained, and the left reversibility of the established speed and displacement subsystem is proved. Thirdly, the left inverse systems of the speed and displacement subsystems are constructed by using the LS-SVM, and the complete speed and displacement sensorless control system is constructed. Finally, the simulations and experiments of the proposed method are performed. The research results demonstrate that the proposed observation method can identify the speed and displacement quickly and accurately, and the sensorless control method can realize the stable operation of the BPMSM without speed and displacement sensors.

Dead-Time Correction Applied for Extended Flux-Based Sensorless Control of Assisted PMSMs in Electric Vehicles

Sensorless control technology of PMSMs is of great importance for safety and reliability in electric vehicles. Among all existing methods, only the extended flux-based method has great performance over all speed range. However, the accuracy and reliability of the extended flux rotor position observer are greatly affected by the dead-time effect. In this paper, the extended flux-based observer is adopted to develop a sensorless control system. The influence of dead-time effect on the observer is analyzed and a dead-time correction method is specially designed to guarantee the reliability of the whole control system. A comparison of estimation precision among the extended flux-based method, the electromotive force (EMF)-based method and the high frequency signal injection method is given by simulations. The performance of the proposed sensorless control system is verified by experiments. The experimental results show that the proposed extended flux-based sensorless control system with dead-time correction has satisfactory performance over full speed range in both loaded and non-loaded situations. The estimation error of rotor speed is within 4% in all working conditions. The dead-time correction method improves the reliability of the control system effectively.

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.

Improved sensorless control scheme for PMSM based on high-frequency square-wave voltage injection considering non-linear change of inductance in D-Q axis

Aiming at the position sensorless control system of permanent magnet synchronous motor (PMSM), an improved high-frequency square wave (HFSW) signal injection scheme considering nonlinear inductance variation in d-q axis is proposed and implemented in this paper. Compared with the existing model, the modified scheme can take the dynamic variation of d-q axis inductance under different operation conditions into consideration by offsetting the resulting high-frequency incremental (HFI) current harmonic components, thus effectively suppressing the estimation error of the rotor position. The experimental results verify that the improved scheme proposed in this paper can not only improve the estimation accuracy of rotor position impaired by the non-linear variations of d-q axis inductance but also maintain the good steady-state and dynamic performance of traditional schemes.

ОБЗОР МЕТОДОВ ОЦЕНИВАНИЯ ПАРАМЕТРОВ СХЕМЫ ЗАМЕЩЕНИЯ АСИНХРОННОЙ ЭЛЕКТРИЧЕСКОЙ МАШИНЫ ДЛЯ ОРГАНИЗАЦИИ ВЕКТОРНОЙ СИСТЕМЫ УПРАВЛЕНИЯ

Relevance Today, due to the well-known and proven by many years of positive qualities of successful operation, induction machines (IM) have found wide application in various industries [1, 2], as part of motor [3–5] and generator sets [6–8]. The main advantages of an IM include simplicity of design, relatively low cost, the ability to withstand short-term current overloads, the absence of a brush-collector unit and expensive rare-earth magnets [9–14]. The relevance of the use of IM, which has not lost over the years, is confirmed, in particular, by modern manufacturers of electric vehicles [15], for which the issue of the most rational use of electricity is in the first place. The development of the principles of the theory of control of asynchronous controlled electric drives led to the emergence of various IM control methods, implemented in modern microprocessor-based frequency converters. These control methods include U/f control, field oriented control and direct torque control in various modifications and combinations [16–18]. The listed control methods have their own areas of application and are, to varying degrees, demanding on the availability of the parameters of the IM equivalent circuit used as part of the electric drive [19, 20]. Setting incorrect settings of the control system, based to the greatest extent on the parameters of the IM equivalent circuit, can lead to deterioration in the quality of regulation, as well as to a decrease in the energy efficiency of the electric drive [21–24]. It should be noted that the most acute problem with the availability of correct estimates of IM parameters arises when constructing sensorless control systems for electric drives [25]. Aim of research Review and compare the main methods estimation of induction motor equivalent circuit parameters used to organize a closed-loop control system of an electric drive. Research methods In this study, the following methods were used: study of scientific literature, study and generalization of information, comparison. Results The need to find estimations of IM equivalent circuit parameters for organizing a field oriented control system for an electric drive. A comparative analysis is carried out, the advantages and disadvantages of the main groups of methods for finding estimates of the parameters of an IM are described.

An Improved Full-Order Sliding-Mode Observer for Rotor Position and Speed Estimation of SPMSM

This paper proposed an improved full-order sliding-mode observer (IFSMO), applied to a sensorless control system of surface-mounted permanent magnet synchronous motor (SPMSM), to obtain a high-precision rotor speed and position. First, the IFSMO method, which combines the new sliding-mode function with the variable boundary layer function, is presented to suppress the chattering and accelerate the convergence speed of the system. Meanwhile, since the observer has the characteristics of a second-order low-pass filter, the high-frequency noise contained in the estimated back EMF signal can be effectively filtered out without an additional low-pass filter. Then, the proposed PLL is designed to obtain rotor position and speed. Finally, simulations and experiments of the SPMSM system based on the IFSMO method under different working conditions are implemented, which demonstrates the effectiveness of the proposed algorithm.

Position Sensorless Control System of Permanent Magnet Synchronous Linear Motor Based on Sliding Mode Observer with an Improved Phase-Locked Loop

In this paper, position sensorless control system of permanent magnet synchronous linear motor (PMSLM) based on sliding mode observer (SMO) with an improved phase-locked loop (PLL) is studied. Firstly, according to the mathematical model, a SMO is designed for sensorless control PMSLM drive. Thereafter, an improved PLL is proposed to tackle the imperfection of data overflow existed in the traditional PLL. The designed SMO incorporating with the improved PLL can be effectively suppress the pulsation of the estimated position and hence the chattering of the derived electrical angular velocity. At last, simulated and experimental results are presented to verify the effectiveness and feasibility of the position sensorless control system.

Compressed Extended Kalman Filter for Sensorless Control of Asynchronous Motor

The sensorless control applications of Induction Motors (IM) are largely expanding in industrial applications. This paper presents a new and effective sensorless control approach for IM drive based on Compressed Extended Kalman Filter (CEKF). Moreover, the estimations of the rotor flux components and the IM motor speed are implemented through CEKF algorithm. The effectiveness of the proposed control system of IM and estimation algorithm has been verified through simulation work using MATLAB/Simulink at different torque loads. Furthermore, the estimation scheme has been experimentally tested at full load. The comparison between the Extended Kalman Filter (EKF) and the CEKF are carried out and satisfying simulation and experimental results have shown that the CEKF algorithm is very effective in estimating the IM states with lower computational costs, low storage memory and less complexity during implementation compared to the EKF. The sensorless control system has demonstrated good performance at different torque loads conditions. Copyright © 2020 Praise Worthy Prize - All rights reserved.

Research on the SCVM Flux Error MRAS Observer of Asynchronous Motor Based on SMC

Aiming at the sensorless control system of asynchronous motor, a MRAS observer method for asynchronous motor SCVM flux error based on sliding mode control (SMC) is proposed. This method uses the SCVM voltage model flux error to form a MRAS observer to identify the speed and estimate the rotor flux, and a sliding mode speed controller is designed to replace the traditional PI speed controller. The algorithm can reduce the overshoot of the dynamic response of the system speed at medium and high speeds, shorten the time to enter the steady state value, and enhance the robustness of the system. Simulation results show the effectiveness of the algorithm.

Laboratory model of a magnetic levitation system

The magnetic levitation consists of balancing the forces of attraction and repulsion of a ferromagnetic object located in a foreign magnetic field in such a way as to keep a desired distance between the object and the magnet. This technology is receiving increasing attention because it helps to eliminate the frictional losses due to the lack of mechanical contact. This makes it possible to reduce the wear of critical machine parts and achieve high speeds with increased positioning accuracy. Advanced applications include the high-speed Maglev trains, magnetic bearings and suspension, electromagnetic cranes, high-accuracy positioning of wafers in photolithography in the manufacturing of integrated circuits, and other high-precision contactless positioning devices. Positive results are also observed in applications from the mining and processing industry in the extraction and processing of raw materials, which makes the topic relevant. The paper presents a laboratory model of a single degree of freedom electromagnet-based system intended to aid the studying of the effect of magnetic levitation. The possibilities for the implementation of different positional feedback types are discussed together with the power circuit that drives the electromagnet. A mathematical model and implementation of a fully digital algorithm that uses the PID control law are presented. Experiments are conducted that could aid in building a sensorless control system. The elaborated laboratory model allows for easy upgrade and can be used in disciplines in the field of measurement, control, and automation as a whole.

Design of sensorless high speed BLDCM controller for molecular pump

The brushless direct current motor(BLDCM) of the molecular pump needs to run at high speed for a long time, which puts forward the requirements of high reliability, high speed rang and so on. The traditional sensor methods of using hall sensors for BLDCM commutation will reduce the reliability of the system and increase costs. Therefore, sensorless control methods are widely used in the field of molecular pumps. In this paper, a sensorless BLDCM control system of the molecular pump is designed, and the back-EMF zero crossing detection method is used to obtain the motor position information. Based on this method, the hardware and software of the control system are designed. Driven by the controller, the molecular pump speed can reach 90000rpm, and its steady speed fluctuation is ± 60rpm.

Adaptive Maximum Torque per Ampere Control of Sensorless Permanent Magnet Motor Drives

Interior permanent magnet synchronous motor (IPMSM) efficiency can be improved by using maximum torque per ampere control (MTPA). MTPA control utilizes both alignment and reluctance torques and usually requires information about the magnetization map of the electrical machine. This paper proposes an adaptive MTPA algorithm for sensorless control systems of IPMSM drives, which is applicable in industrial and commercial drives. This algorithm enhances conventional control schemes, where the output of the speed controller is the commanded stator current and the direct current is calculated using an MTPA equation; therefore, it can be easily implemented in the previously developed drives. The proposed algorithm does not use any motor parameters for the calculation of the MTPA trajectory, which is important for systems operating in changing environmental conditions, because motor inductances and flux linkage strongly depend on the stator current and the rotor temperature, respectively. The proposed algorithm continuously varies the current phase and in such a way it tries to minimize the magnitude of the stator current at the applied load torque. The main contribution of this paper is the development of a technique to overcome the main disadvantage of seeking algorithms–the necessity of a precision information about the rotor position. The proposed method was verified experimentally.

An Extended Kalman Filter, with pre-adjusted covariance matrices, applied to the sensorless speed control of three-phase induction motors

With the emergence of sensorless control methods, there was a need for the use of estimators and/or state observers to give it the robustness and precision required in the drive of induction motors. This work deals with the application of the Extended Kalman Filter (EKF) in the estimation of rotor speed and position, aiming at the implementation of the indirect vector control technique in a sensorless speed control system for three-phase induction motors. The mathematical development of the system state variables associated with the EKF stochastic process is presented in this study, and point out its application under variable speed and load conditions, which are imposed on these motors in everyday life. The sensorless control strategy was tested through routine lines in the Matlab® software, simulating operating conditions of this type of engine, being proven its performance, as well as the convergence times consistent with the usual requirements of high performance systems. The main contributions of this work are the use of a reduced-order EKF (ROEKF) and the preset of covariance matrices to accelerate convergence in speed and position estimates for future implementations in currently accessible digital signal processors.

Robustness Improvement of Model-Based Sensorless SPMSM Drivers Based on an Adaptive Extended State Observer and an Enhanced Quadrature PLL

Conventional model-based sensorless surface-mounted permanent magnet synchronous motor (SPMSM) drivers suffer deteriorated performance in transient-state operation such as accelerating during wide-speed range or encountering large load torque disturbance. In this article, an effective sensorless control solution is proposed to improve the robustness of sensorless SPMSM drivers in transient-state operation. Two extended state observers (ESOs) are utilized to estimate the αβ-axis back electromotive forces (EMFs). An adaptive bandwidth tuning scheme is proposed to online tune the parameters of the ESOs, with which the desired estimation performance of back EMFs can be achieved in wide-speed operation range. Additionally, the dynamic mechanical behavior of the sensorless control system during large load torque transient is investigated by using small-signal analysis, and then a corresponding speed estimation compensation scheme for the conventional quadrature phase-locked loop (QPLL) is developed, with which the capability of QPLL in tracking the rapidly changing speed can be significantly enhanced. Experiments on an SPMSM demonstrate the superior robustness of the proposed method to that of the conventional method in transient-state operation.

Radial Displacement Sensorless Control of Bearingless Flux-Switching Permanent Magnet Machines Based on Difference of Symmetric-Winding Flux Linkages

A feedback signal of the rotor radial displacement is essential for realizing the stable suspension for bearingless flux-switching permanent magnet machines (BFSPMMs). Although the recent smart sensors technology is developing rapidly, the mechanical sensors will increase the complexity of the system while reduce its reliability. Thus, an alternative is urgently needed to achieve the compact and practical motor structure. Herein, a novel rotor radial displacement observer is presented, and a radial displacement sensorless control system based on the observer for a BFSPMM is built. First, the mathematical model of the motor concerning rotor eccentricity is established. The theoretical expressions of flux linkages are derived, which are closely related to the eccentric distance and angle. Second, the rotor displacement signal is estimated by the difference of the symmetric-winding flux linkages. And a closed-loop compensation method is designed to reduce the phase lag of the signal in the observer due to the filter. Besides, the convergence regarding the proposed observer is analyzed. Ultimately, the observed result is used as a feedback signal to control the suspension force of the system. The simulation and experimental results verified the validity of the proposed scheme.

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.

Speed Observer Structure of Induction Machine Based on Sliding Super-Twisting and Backstepping Techniques

This article presents an analysis of the two speed observer structures which are based on the backstepping and sliding super twisting approach. The observer stabilizing functions result from the Lyapunov theorem. To obtain the observer tuning gains the observer structure is linearized near the equilibrium point. The rotor angular speed is obtained from nonadaptive dependence. In the sensorless control system structure the classical PI controllers and transformation to the multiscalar variables are applied. The theoretical derivations are verified in experimental waveforms. Comparison of both speed observer structures is presented for nominal speed, load torque injections while regenerating mode, very low speed range and the uncertainties of nominal parameters of induction machine.

A SYNCHRONIZATION LOSS DETECTION METHOD FOR PMSM SPEED SENSORLESS CONTROL

Permanent Magnet Synchronous Motor (PMSM) is an AC motor in which the rotor must operate at synchronous speed in all load conditions. If the motor mechanical load increases, the motor can lose synchronization, stopping the motor. In sensorless control systems, i.e., those without speed sensors, the speed is estimated from the stator current using the Model Reference Adaptive System (MRAS) algorithm. Because such systems therefore cannot detect the loss of synchronization, it is necessary to design a synchronization loss detection system. Here, another speed estimation calculated from the stator currents and voltages is introduced. The speed is called a calculated speed. In the normal condition (synchronous condition), estimated speed and calculated speed will be approximately equal. However, when synchronization loss occurs, these two speed values diverge. On the basis of this phenomenon, a synchronization loss detection algorithm and method are developed. The algorithm’s speed-delta boundary values and detection period must be determined. The greater the setpoint speed, the higher the speed-delta boundary values but the smaller the detection period. The experiments confirm that the proposed algorithm is able to effectively detect the occurrence of synchronization loss.