Sensorless Control of Multi-Motors PMSM using Back-EMF Sliding Mode Observer

Motor Brushless Direct Current (BLDC) has become the preferred choice in various engineering applications. However, BLDC motor control involves high complexity, and motor performance depends on the control algorithms used. This research discusses the use of sensorless control methods, specifically the Sliding Mode Observer (SMO) for rotor position and speed estimation in BLDC motors within the context of Field-Oriented Control (FOC), validated through simulations using Matlab/Simulink. Simulation results indicate that SMO provides rapid dynamic response to current changes, albeit with slight delays at high speeds. Rotor position estimation with SMO is also reasonably accurate in both steady-state and transient conditions, affirming the iveness of SMO in sensorless control for BLDC motors. SMO can be experimentally implemented to enhance sensorless control in BLDC motors by reducing the cost of installing Hall sensors while maintaining comparable performance.

ABSTRACTThis paper proposes a new method to detect the initial rotor position at standstill of permanent magnet synchronous motor (PMSM). To estimate rotor position and rotor speed from the back electromotive force (EMF) voltage, we apply sensorless speed control based on sliding-mode observer (SMO). The initial rotor position is detected by using a suitable high-frequency sequence of voltage pulses intermittently applied to the stator windings at standstill. With this approach, we managed to minimise the error on the estimated position to 3.75° electrical degrees without additional materials and uncomplicated calculations. The stability of the proposed SMO was verified using the Lyapunov method. Numerical simulations and experiments demonstrate that the novel SMO method can effectively estimate rotor position and speed with achievement of good static and dynamic performance. The experimental implementation is carried out on powerful dSpace DS1103 controller board based on the digital signal processor (DSP) TMS320F240.

Based on the FPGA (Field Programmable Gate Array), this paper presents an implementation of a sensorless PMSM speed control system which the rotor speed and rotor position are estimated by novel SMO method. The estimated rotor position can be sent back to the current loop for vector control and the estimated rotor speed can be fed back to the speed loop for closed-loop speed control. In realization, the digital hardware IP (Intellectual Property) regarding as the speed controller, the current vector controller and novel SMO algorithm are described by VHDL. Finally, to confirm the correctness and effectiveness of the proposed sensorless speed control IP (Intellectual Property), a design procedure from ModelSim/Simulink co-simulation to FPGA realization is applied and an experimental PMSM drive system is demonstrated.

This article presents a Permanent Magnet Synchronous Motor (PMSM) sensorless control system using backstepping control. The Extended State Observer (ESO) is also used to perform the sensorless control, and to estimate the load torque which is considered an external disturbance of the control system. Starting from the classic Field Oriented Control (FOC) type PMSM control structure, the classic PI speed and current controllers i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> , i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> are replaced by a backstepping control structure. The main blocks used for the implementation and numerical simulation in the Matlab/Simulink graphical programming environment are presented. The very good static and dynamic performance obtained through numerical simulations even at high speeds, step variations of the value of the load torque, uniformly distributed noise, and variations of the PSMS nominal parameters can be explained by the fact that the backstepping control is applied to the non-linear system of the PMSM and by the step-by-step method of achieving each iqref, ud and uq control by using a Lyapunov-type function. Future articles propose the approach of real-time implementation of the PMSM sensorless control by using the backstepping control.

In this article is presented a sensorless control structure of the speed of a Permanent Magnet Synchronous Motor (PMSM) rotor based on the classic Field Oriented Control (FOC) strategy, where the PI outer speed loop controller in the classical approach supplies the current reference i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">qref</sub> for a Synergetic controller, which supplies the output controls u <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> and u <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> for the PMSM control. The synergetic control is considered as a generalization for the Sliding Mode Control (SMC). Among the remarkable properties of this type of design of control are the decoupling procedure and a reduced order model for the controller. The PMSM operating equations, fractional order calculus elements and a Sliding Mode Observer (SMO) type speed observer of are presented herein. By replacing the Synergetic current controller with a Fractional Order (FO) Synergetic current controllers, superior performance is achieved due to the use of the fractional calculus.

This study proposes a high-performance sensorless interior permanent-magnet synchronous motor control system using a high-frequency injection technique. A new estimation method that uses both the high-frequency d-axis current and q-axis current to estimate the rotor position is investigated. By using the proposed method, the hypothesis-synchronisation signal used in the conventional high-frequency injection method can be eliminated. A 1.25 kHz, 15 V, sinusoidal waveform voltage is injected into the d-axis synchronous frame of the motor and then the high-frequency d-axis and q-axis currents can be measured to determine the rotor position of the motor. In addition, a new compensation method is developed to reduce the estimation position error because of the mutual inductance and saturation effect of the motor. By using this new method, the estimated rotor-position error is within ±2 electrical degrees. A digital signal processor, TMS-320-F2812, is used as the estimating and control centre. The experimental results show that the proposed method can be applied in both a sensorless speed control system and a sensorless position control system. The sensorless speed control system has fast response, good load disturbance response and good tracking response.

This article reviews the state-of-the-art back electromotive force (EMF) based sensorless schemes for synchronous machines. Field-oriented control (FOC) of a synchronous machine requires real-time rotor position for decoupled torque and flux control. Extraction of rotor position without a sensor or sensorless control has been an enabling technology for the past few decades. Sensorless control using back EMF voltage induced by rotor movement is the most widely used method. However, the connections and differences between different methods have not been thoroughly investigated and documented. This article first reviews basic sensorless methods. The two implementation forms of an observer are examined to facilitate analysis. A detailed analysis puts in evidence the connections behind different methods in both stationary and synchronous reference frames. A summary is drawn that is meant to offer a few key points regarding different sensorless methods. Finally, a conclusion is given to summarize the major contributions of this article.

This article presents the sensorless control of a PMSM based on the FOC (Field Oriented Control) strategy and on PFC (Power Factor Correction), where the rotor speed is provided by speed observers. It presents the block structure of the PFC together with the numerical simulations achieved in Matlab/Simulink, on the improvement of the PF (Power Factor) of the supply circuit. It also presents the block structures of the FOC strategy and of the back-EMF (back electromotive force) sliding mode, MRAS (Model Reference Adaptive System), and PLL (Phase Locked Loop) type observers. The numerical simulations show the superiority of rotor speed estimation when using the back-EMF sliding mode observer compared to the rotor speed estimate provided by MRAS and PLL observers.

The speed control of induction motors can be divided into two distinct strategies, depending on the type of dynamics that is required: scalar control (static control of the torque) and vector control (dynamic control of the torque) (Blaabjerg et al. 2005; Bose, 2000, 2006; Filote et al. 2009; Holtz, 2002; Leonhard, 1990; Umanand & Bhat, 1995; Vas, 1998). Since the couple and flux levels depend on the motor behavior to frequency and voltage applied to it, maintaining the flux constant is strongly required in scalar control (V/f control). Despite the simplicity and the low cost implementation of the control method, it still presents the disadvantage of poor torque dynamics. Vector control reassesses one of the advantages of direct current (dc) drives, which is the separation of speed and couple loops. According to its structure and to its own functioning principle, the dc drive is naturally field oriented, hence, the separation of the speed and current loops. In the case of vector controllers of induction motor, the magnitude and phase stator current are controlled in accordance with the flux vector. There are three vector control strategies according to the type of drive-controlled flux: stator flux, rotor flux and air gap flux. We can determine the magnitude and position of the rotor flux by using flux sensors (direct field-oriented control), estimators or observers (indirect field-oriented control) and by measuring some electrical and mechanical measurable states of electrical drives induction motor systems. When the rotor flux estimation is performed after measuring only the electrical measurable states (voltages and stator currents), in this case we have a sensorless vector control system. The implementation of the direct field-oriented control requires the measurement or calculation of the flux space vector (magnitude and position). The measurement of the air gap flux requires the use of some Hall sensors (Umanand & Bhat, 1995), which requires specially constructed induction motor. On one hand, they are very sensitive to temperature and mechanical vibrations. The flux signal is highly distorted by slot harmonics (Kreindler, 1994), whose spectrum and amplitude depend on the rotor speed (hence, the difficulty to be filtered). The implementation of the indirect field-oriented control requires the identification of rotor flux instantaneous position, and the calculus of stator current prescribed value in sensorless vector control system (Gadue et. al. 2009; Griva et al. 1997; Lascu et al. 2004). The

In this article, a sensorless field-oriented vector control strategy combined with an improved adaptive sliding mode observer and a back electromotive force (back EMF) observer is presented for a surface permanent magnet synchronous motor. First, based on a sliding mode, a current adaptive observer with estimation of back EMF is proposed to obtain the error of the back EMF, which can reduce system chattering. Then, a back EMF observer based on the back EMF error is constructed to adaptively track the rotor speed and position, which avoids complicated computation. Moreover, the stability of two observers is proved by using the Lyapunov stability theory. Finally, some simulations and experiments are given to show that the proposed method can track the changes of rotor speed and position with good characters, such as fast convergence, little chattering, and good robustness.

The electronic water pump will be used more and more widely in the new energy vehicles and other special vehicles. A sensorless electronic water pump for automobile is designed and implemented with the brushless direct current motor (BLDCM) as the driving motor. A sensorless magnetic field oriented control (FOC) scheme using sliding mode observer (SMO) is applied for the motor control. A novel SMO and the phase-locked loop (PLL) for reducing the chattering phenomenon are used to estimate rotor velocity/position from the back electromotive force (EMF), in which a continuous saturation function is applied instead of the sign function. A robust I-f startup strategy is introduced. The hardware circuit design and software algorithm design are presented. The experimental system is set up and some experimental results are demonstrated. The effectiveness and correctness of the proposed hardware design and the software scheme are validated. Experimental results show that the developed electronic water pump is reasonable and feasible with a high cost performance.

In this article is presented a type of sensorless control system for a PMSM using a Sliding Mode Control (SMC) type controller, which replaces the PI-type controller of a PMSM rotor speed control loop, and the speed is estimated using a Sliding Mode Observer (SMO) type observer. For the detection of the faults from power supply lines given by current sensors of the PMSM, the Fault Detection Observer (FDO) type observer is used. The equations of the SMC-type controller, of the SMO-type observer, and of the fault detection observer, as well as their implementation in Matlab/Simulink graphical programming environment are presented in this article. Following the numerical simulations, the special performances of the SMC-type controller are presented, but also as compared to the PI speed controller in the classic Field Oriented Control (FOC) type structure. The FDO-type observer has a good response time and works with good results even under the conditions where uniformly distributed disturbances act on the system. The future papers will approach the methods of implementation in real time in embedded system of the SMC control and of the described observers.

In permanent magnet synchronous motors (PMSMs) sensorless control, the sliding mode observer (SMO) has emerged as a solution for rotor position estimation due to its advantages of high robustness, low cost, and superior dynamic performance. However, the inevitable aperiodic and periodic disturbances present in the control system can induce harmonics in the back electromotive force (EMF), which affect the accuracy of position estimation. Conventional sliding mode observer with low-pass filter (SMO-LPF) inevitably introduces phase lag, parameter sensitivity, and signal discontinuity issues. This paper proposes a novel composite controller that combines enhanced repetitive control (ERC) and SMO. The method utilizes the periodic signal suppression capability of repetitive control (RC) to compensate for the harmonics of current, thereby reducing the interference of low-order harmonics on position observation. Additionally, approach ensures the stability of the sliding mode while retaining the strong robustness of the SMO. The simulation results demonstrate that the proposed controller exhibits excellent harmonic suppression capability in terms of magnitude-frequency characteristics. Furthermore, comprehensive simulation experiments including dynamic response analysis, robustness testing, and speed estimation accuracy verification have conclusively validated the effectiveness of the novel approach.

The field-oriented control (FOC) strategy of a permanent magnet synchronous motor (PMSM) in a simplified form is based on PI-type controllers. In addition to their low complexity (an advantage for real-time implementation), these controllers also provide limited performance due to the nonlinear character of the description equations of the PMSM model under the usual conditions of a relatively wide variation in the load torque and the high dynamics of the PMSM speed reference. Moreover, a number of significant improvements in the performance of PMSM control systems, also based on the FOC control strategy, are obtained if the controller of the speed control loop uses sliding mode control (SMC), and if the controllers for the inner control loops of id and iq currents are of the synergetic type. Furthermore, using such a control structure, very good performance of the PMSM control system is also obtained under conditions of parametric uncertainties and significant variations in the combined rotor-load moment of inertia and the load resistance. To improve the performance of the PMSM control system without using controllers having a more complicated mathematical description, the advantages provided by reinforcement learning (RL) for process control can also be used. This technique does not require the exact knowledge of the mathematical model of the controlled system or the type of uncertainties. The improvement in the performance of the PMSM control system based on the FOC-type strategy, both when using simple PI-type controllers or in the case of complex SMC or synergetic-type controllers, is achieved using the RL based on the Deep Deterministic Policy Gradient (DDPG). This improvement is obtained by using the correction signals provided by a trained reinforcement learning agent, which is added to the control signals ud, uq, and iqref. A speed observer is also implemented for estimating the PMSM rotor speed. The PMSM control structures are presented using the FOC-type strategy, both in the case of simple PI-type controllers and complex SMC or synergetic-type controllers, and numerical simulations performed in the MATLAB/Simulink environment show the improvements in the performance of the PMSM control system, even under conditions of parametric uncertainties, by using the RL-DDPG.

This paper presents a sensorless control method for an IPMSM, which are based on the combination of the modified Fundamental Excitation PWM (FPE) method and the Sliding Mode Observer (SMO). At low speeds the current derivatives at the first active-voltage vector are measured to estimate rotor speed, position and machine inductances, while at medium and high speeds the SMO is employed for sensorless control. The estimated L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> and L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> at low speeds are stored in a look up table and utilized for enhancing the performance of the SMO. The experimental studies have been conducted to verify the improvement of the estimation accuracy and the reduction of the current distortion over a full speed range from zero to rated speed of the proposed hybrid sensorless control method.