Sensorless wet clutch pressure control method for high-power tractors using physical and digital twins

PurposeThis paper mainly aims to deal with the problems of uncertainties including modelling errors, unknown dynamics and disturbances caused by load mutation in control of permanent magnet synchronous motor (PMSM).Design/methodology/approachThis paper proposes an enhanced speed sensorless vector control method based on an active disturbance rejection controller (ADRC) for a PMSM. First, a state space model of the PMSM is obtained for the field orientation control strategy. Second, a sliding mode observer (SMO) based on back electromotive force (EMF) is introduced to replace the encode to estimate the rotor flux position angle and speed. Third, an infinite impulse response (IIR) filter is introduced to eliminate high frequency noise mixed in the output of the sliding mode observer. In addition, a speed control method based on an extended state observer (ESO) is proposed to estimate and compensate for the total disturbances. Finally, an experimental set-up is built to verify the effectiveness and superiority of the proposed ADRC-based control method.FindingsThe comparative experimental results show that the proposed speed sensorless control method with the IIR filter can achieve excellent robustness and speed tracking performance for PMSM system.Research limitations/implicationsAn enhanced sensorless control method based on active disturbance rejection controller is designed to realize high precision control of the PMSM; the IIR filter is used to attenuate the chattering problem of traditional SMO; this method simplifies the system and saves the total cost due to the speed sensorless technology.Practical implicationsThe use of sensorless can reduce costs and be more beneficial to actual industrial application.Originality/valueThe proposed enhanced speed sensorless vector control method based on an ADRC with the IIR filter enriches the control method of PMSM. It can ameliorate system robustness and achieve excellent speed tracking performance.

A new method for sensorless control of the switched reluctance motor (SRM) drive is presented in this paper. This new sensorless control method is based on the stiff system control concept and signature detection technique. Suppose, initially, the SRM is controlled without any position sensor and running at synchronous operation with each phase current pulse resting on the positive phase inductance slope. A load disturbance will cause the rotor speed to change and each phase current pulse to shift along with the phase inductance profile. The rotor speed will change much slower than the phase currents because the mechanical time constant is much larger than the electrical time constant. If there exists a signature in the phase current, indicating the shifting of the phase current pulse, the controller can detect the shifting of the phase current pulses by monitoring this current signature and correct the phase excitation to bring the current pulses back to the positive inductance slopes before the rotor speed changes too much. This can be done because the control time constant is much smaller than the electrical time constant. Simulation and experimental results are presented to show the validity of this sensorless SRM control method.

This paper develops a new method of sensorless control for brushless DC (BLDC) machines. The new sensorless control method utilizes relative rotor position feedback information which is extracted from the hysteresis chopping of the sensed phase current waveforms in a nonsalient, trapezoidal back-EMF, surface-mounted permanent-magnet BLDC. Details of the new method of sensorless brushless DC control are revealed. The existence and uniqueness of the hysteresis waveform feedback information is shown. A simulation of two modes of the new sensorless control and experimental validation are performed.

A micro-hand is a remarkable soft actuator, it is expected to apply in medical, biological and welfare fields because of the high safety to fragile objects. In the previous research, a sensorless adaptive control method using support vector regression has been proposed. In this paper, a nonlinear control scheme by using image information is proposed, it is a different method from the sensorless control method. Experimental results are shown to verify the effectiveness of the proposed method.

Relevance of study. Starting of the medium voltage synchronous machine at standstill is one of the main problems in the operation of unregulated synchronous electric drives. The optimal solution is starting the excited synchronous machine fed by the thyristor statical frequency converter. A sensorless control of the statical frequency converter for thyristor switching of load-commutated inverter to functions of synchronous machine angular rotor position in the area of zero and low speed, has not yet received a clear solution.
 
 The purpose of this study is the design of the sensorless control method for the thyristor statical frequency converter at the synchronous machine startup under conditions of angular acceleration uncertainty.
 
 Materials and methods. Methods of theory of electrical machines and computer mathematical simulation are used in the study.
 
 Results of the study. The regularity between the angular rotor position and the non-conductive phase stator voltage of the synchronous machine is determined. The rotor rotation angle of the synchronous machine is defined as the ratio of the conductive state duration of the thyristor arm pair of the load-commutated inverter to the period determined from the non-conductive phase stator voltage of the synchronous machine. The sensorless control method is based on simultaneous operation of scalar control, indirect angular rotor position determination and cross-control channels. The proposed sensorless control method is tested by computer mathematical simulation of the system «thyristor statical frequency converter –synchronous machine».
 
 Findings. The application of the considered control method was found for commercially available medium voltage thyristor frequency converters of EKRA Ltd. The considered method can be used for the sensorless control of frequency converter by different topology.

Even if there exists remarkable applications of induction machines in variable speed drives and also in speed sensorless control in the low–high speed region, open/closed loop estimators in the literature utilized on induction machine sensorless position control vary regarding to their accuracies, sensitivity, and robustness with respect to the variation of model parameter. The deterioration of dynamic performance depends on the lack of estimation techniques which provide trustable information on the flux or speed/position over a wide speed range. An effective estimator should handle the high number of parameter and model uncertainties inherent to induction machines and also torque ripple, the compensation of which is crucial for a satisfactory decoupling and linearizing control to provide the accuracy and precision requirements of demanding motion control in the field of robotics/unmanned vehicle. In this study, to address all of the above-mentioned problems, robust-adaptive linearizing schemes for the sensorless position control of induction machines based on high-order sliding modes and robust differentiators to improve performance were designed. The control schemes based on direct vector control and direct torque control are capable of torque ripple attenuation taking both space and current harmonics into account. The simulation results comprise both the estimation and sensorless speed control of induction machines over a wide operation range, especially at low and zero speed, all of which are promising and indicate significant superiority over existing solutions in the literature for the high precision, direct-drive, speed/position sensorless control of squirrel-cage induction machines.

The demand for sensorless control of surface permanent magnet synchronous motor (SPM) drives has grown tremendously over the past decade in a wide variety of industrial applications. Many different sensorless control methods have been proposed for SPM, especially the Matsui's current model-based method and the extended Kalman filter based methods have gained much attention. However, the performance of these sensorless control methods are severely worsened or may even become unstable under strong disturbances and sensing measurement failure conditions. This paper presents a novel resilient extended Kalman filter based sensorless direct torque and flux control approach of permanent magnet synchronous motor drives. The robustness against external disturbances and sensing failures can be improved by applying the proposed nonlinear estimation approach. Computer simulation studies and hardware implementation results have shown the superior performance of the proposed approach.

In general, sensorless control methods for Permanent Magnet Synchronous Machine (PMSM) are classified into saliency tracking based method and fundamental model based method. In the fundamental model based method, the rotor position and speed can be estimated based on the mathematical model of PMSM. The typical fundamental models for sensorless control are classified into current model and voltage model. In this paper, a mixed model is proposed as a fundamental model for sensorless control. The mixed model has characteristics of both models. The current model is dominant in low speed range, and the voltage model is dominant in high speed range. Thus, the mixed model based sensorless control method is robust in wide speed range. For the sensorless control, the mixed-model based back electromotive force (EMF) state observer and speed estimator are proposed in this paper. The validity of the proposed sensorless control method is verified by the experimental results with 3.7 kW PMSM drive system.

This thesis presents the modeling, analysis, design and experimental validation of a robust sensorless control method for permanent magnet synchronous motor (PMSM) based on Extended Kalman Filter (EKF) to accurately estimate speed and rotor position. Currently, there is no robust position/speed sensorless control method available for the permanent magnet synchronous motor (PMSM) in the published literature. Traditionally, commercial off-the-shelf simulation models for PMSM do not incorporate initial rotor position and simplified steady-state based modeling of the associated power electronic circuitry and controls are used. These limitations have prevented the development and application of a robust real-time sensorless control method with good dynamic performance over the full speed range for the PMSM. The main focus of this thesis is to overcome these limitations. In particular, a detailed real-time PMSM model in MATLAB/Simulink simulation environment is developed which is used to validate the EKF sensorless control method by varying the initial position of the rotor. The proposed position/speed sensorless control based on EKF method along with all the power electronic circuitry are modeled in this simulation environment. This user-friendly simulation and rapid-prototyping platform is then effectively used to predict, analyse, fine-tune and validate proper operation of the proposed EKF sensorless control method for all operating conditions. In particular, different control strategies are reviewed and the performance of the proposed EKF sensorless control method is critically assessed and validated for different types of dynamic and static torque loads. The robustness of the proposed EKF sensorless method is demonstrated by validating proper operation of the closed-loop motor control system for different rotor initial positions and insensitivity of the EKF speed/position estimation method to the PMSM parameter variations. Proper operation of the proposed EKF based sensorless control method for a high speed permanent magnet synchronous machine is verified experimentally in the lab at Honeywell.

This thesis presents the modeling, analysis, design and experimental validation of a robust sensorless control method for permanent magnet synchronous motor (PMSM) based on Extended Kalman Filter (EKF) to accurately estimate speed and rotor position. Currently, there is no robust position/speed sensorless control method available for the permanent magnet synchronous motor (PMSM) in the published literature. Traditionally, commercial off-the-shelf simulation models for PMSM do not incorporate initial rotor position and simplified steady-state based modeling of the associated power electronic circuitry and controls are used. These limitations have prevented the development and application of a robust real-time sensorless control method with good dynamic performance over the full speed range for the PMSM. The main focus of this thesis is to overcome these limitations. In particular, a detailed real-time PMSM model in MATLAB/Simulink simulation environment is developed which is used to validate the EKF sensorless control method by varying the initial position of the rotor. The proposed position/speed sensorless control based on EKF method along with all the power electronic circuitry are modeled in this simulation environment. This user-friendly simulation and rapid-prototyping platform is then effectively used to predict, analyse, fine-tune and validate proper operation of the proposed EKF sensorless control method for all operating conditions. In particular, different control strategies are reviewed and the performance of the proposed EKF sensorless control method is critically assessed and validated for different types of dynamic and static torque loads. The robustness of the proposed EKF sensorless method is demonstrated by validating proper operation of the closed-loop motor control system for different rotor initial positions and insensitivity of the EKF speed/position estimation method to the PMSM parameter variations. Proper operation of the proposed EKF based sensorless control method for a high speed permanent magnet synchronous machine is verified experimentally in the lab at Honeywell.

Conventional techniques for sensorless control of permanent magnet synchronous motor drive (PMSM) which requires information of rotor position are reviewed and recent developments in this area are introduced in this paper along with their inherent advantages and drawbacks. The paper presents an improved method for sensorless speed control of PMSM drive with emphasis placed on signal injection method. It examines the rotor position sensorless control performance based on sensing by external signal injection. The main objective of this drive system is to have speed control at standstill and low speed regions. Several tests are carried out to demonstrate the ability of proposed models at different operating conditions with the help of simulation results in Matlab/Simulink environment. Simulation results confirm that the proposed sensorless control approach of PMSM can achieve high performance at standstill and low speeds but not at very high speeds.

Control of induction machines without mechanical sensors has gained more and more interest in the past years. Different methods for sensorless control have been proposed in literature recently. The performance of methods, which are based on fundamental wave models of the machine deteriorate at low frequency. To guarantee a stable operation, even at zero fundamental electrical frequency, it is thus necessary to exploit parasitic effects of the machine, which are not visible in normal operation of the drive. All proposed zero-speed methods have in common, that they need an additional excitation of the machine in order to make parasitic saliencies visible. This additional excitation can be a high frequency current or voltage signal of some hundred Hz which is superposed to the fundamental wave, and which may be a rotating or pulsating signal. Another way of excitation can be realised by applying voltage test pulses to the terminals of the machine. These voltage pulses may be either separated from the fundamental wave PWM or they may be integrated into the current control scheme. All mentioned methods evaluate the high frequency current or voltage response of the machine in order to extract a flux- or rotor-position signal. It is thus important to consider the high frequency properties of the lamination sheet when designing a sensorless controlled drive. In this paper, a sensorless control method using voltage test pulses is applied to different induction machines, all with the same winding scheme and lamination design, but with different lamination materials. Thus the materials influence on the sensorless control is evaluated by comparing the different machines control signals. In addition, all machines are equipped with measurement coils at different spots of the machine which enable a comparison of the transient flux linkage change along the air gap of the machine.

The Observer based sensorless control method is very popular and practical in the PMSM sensorless control field. The angle and speed estimation scheme of a typical sensorless control method includes two major part: the back-EMF observer and the angle-speed estimator. In this paper, the traditional observer based sensorless control method is introduced and analyzed. Then, an extended state observer (ESO) based back-EMF estimation solution is proposed, which reconstructs the position information by formulating the back-EMF information as states variable and estimating them online with the observer. Considering that the efficiency of suppressing estimation error is high dependent on the ESO's feedback mechanism, a linear-nonlinear switching strategy is proposed and analyzed to improve existing feedback function. The proposed method not only combines the linear ESO's good tolerance to the disturbance and the nonlinear ESO's high estimation accuracy, but also reduces the nonlinear ESO's sensitivity on parameters and makes it easier to use. As for angle and speed estimation, the traditional PLL method brings ripple and phase delay to the estimated speed. In this paper, an ESO based angle and speed observer is incorporated into the PLL to improve the speed estimation accuracy. Simulation result proves the advantage of the proposed method over the traditional observer-based sensorless control method.

In this paper, a simple signal injection method is proposed for sensorless control of permanent-magnet synchronous machine (PMSM) at a low speed, which ideally requires one voltage vector only for position estimation. The proposed method is easy to implement, resulting in low computation burden. No filters are needed for extracting the high-frequency current signals for position estimation. The use of low-pass filters (LPFs) in the current control loop to obtain the fundamental current component is not necessary. Therefore, the control bandwidth of the inner current control loop may not need to be sacrificed. The proposed method may also be further developed to inject two opposite voltage vectors to reduce the effects of inverter voltage error on the position estimation accuracy. The effectiveness of the proposed method is demonstrated by comparing with other sensorless control method. Theoretical analysis and experimental results are given for validating the proposed new sensorless control method.

Parabolic current control is an attractive current control method with fast transient response and constant switching frequency. Due to the good dynamics of parabolic current control, it can be employed in voltage source inverters to improve the system performance such as minimizing the distortion of current waveforms or voltage waveforms. To implement parabolic current control, a current sensor is required, associated with the current conditioning circuit and parabolic carrier generators. Since parabolic current control is based on the real-time information of the inductor current, any phase delay or propagation delay of the sensor itself and the conditioning circuitry, or limited resolution of parabolic carrier generators, could impact the current control performance. Since the parabolic current control compares analog signals to generate the required control signals, noise from the control board impacts the control precision as well. This paper will explore solutions to these problems. First, the inductor current of voltage source inverter is analyzed and the parabolic current control strategy is studied, then a sensorless parabolic current control method is proposed. The new sensorless parabolic control method utilizes a current emulator to rebuild the inductor current on a micro-controller. To avoid a dc offset on the ac-side output voltage caused by the current emulator, an additional control loop in the current emulator is added. The effectiveness of the proposed methods are experimentally verified by the use of an H-bridge voltage source inverter.