Harmonic suppressed sensorless control for PMSM based on enhanced repetitive compensation sliding mode observer (SMO-ERC)

Based on the application of sensorless control for permanent magnet synchronous motors(PMSM), this paper put forward an improved sliding mode observer(SMO). The conventional SMOs use discontinuous step sign functions as switching functions, which cause chattering problems in the estimation of back electromotive force. Therefore, a smooth activation function is adopted as the switching function. An adaptive reaching law is devised to enhance stability of observing. To address the delay of phase issue caused by low-pass filters(LPF), an adaptive cut-off frequency is designed. The speed and angle information are estimated by using a phase-locked loop(PLL) in the place of of the arctan function, and phase compensation is implemented. Finally, the system of controlling motor is simulated in Matlab to verify that the sensorless control method according to the improved SMO has the effect of reducing chattering and improving the control accuracy of the system.

In high-speed permanent magnet synchronous motor (PMSM) drive systems, low switching frequencies increase discretization errors in conventional sliding mode observers (SMOs). This results in greater harmonics in the estimated stator currents and back electromotive force (EMF), thereby degrading the accuracy of speed and position estimation. This paper investigates steady-state position errors of conventional SMOs under low carrier ratios. The analysis reveals that the primary causes are model discretization errors and quasi-sliding mode motion errors. To address these issues, exact discrete voltage equations are derived in the two-phase stationary reference frame. Subsequently, an improved discrete-domain SMO is developed, incorporating a redesigned back-EMF computation method to enhance speed and position estimation accuracy. Furthermore, to improve dynamic performance under high-speed operating conditions, an adaptive quadrature phase-locked loop (AQPLL) is introduced. This method employs a stochastic gradient descent (SGD) algorithm for online parameter tuning, expanding the bandwidth for faster transient response while maintaining noise immunity at low speeds. The proposed method is validated through experiments on a low-inductance PMSM, demonstrating high estimation accuracy, reduced transient errors, and robust performance under parameter mismatches at a carrier ratio as low as 7.

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.

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.

To improve the speed and position detection accuracy of surface-mount permanent magnet synchronous motor (SPMSM) vector control and reduce unnecessary chattering of the system, this paper proposes a sensorless control strategy of SPMSM based on an adaptive sliding mode observer (ASMO) with optimized phase-locked loop (OPLL) structure. First, in order to overcome the chattering of system caused by discontinuous switching characteristic of signum function in conventional sliding mode observer (CSMO), a continuous saturation function is selected as the switching function. The ASMO adopts the system state-related adaptive gain function to adjust the switching gain value of the system in real time, which overcomes the slow response speed or severe chattering of the system caused by the constant switching gain of CSMO. Second, to reduce the phase delay between the rotor position estimation value and the actual value caused by the adoption of low-pass filter (LPF) and the position estimation error caused by arctangent function method, an OPLL method is designed for accurate estimation of rotor position and speed. Finally, the effectiveness and feasibility of the proposed improved SMO algorithm is verified by simulation and experiments on an SPMSM with rated power of 2 kW.

Permanent magnet synchronous motor (PMSM) is the ideal drive for the magnetically suspended turbo-molecular pump (MSTMP) for its high power density, reliable operation and high energy efficiency. Rotor position information is necessary to drive the PMSM. However, because of the installation space limitation and reliability requirement, position sensorless control technology without mechanical position sensors is more attractive. In this study, a sliding mode observer is adopted to estimate the back electromotive force (EMF) that contains the position information. Since the high-order harmonics in the back EMF would lead to harmonic position errors, a fixed frequency extraction filter is proposed to filter out the harmonics. A high precision speed control is of importance to ensure the performance of the MSTMP and also contributes to achieving a better position estimation accuracy, especially under strong disturbances. Therefore, a composite speed controller combining a sliding mode speed controller and a sliding mode disturbance observer is proposed to improve the speed control performance of the MSTMP. The effectiveness of the proposed high-performance control method for the MSTMP motor is evaluated with experiments.

In sensorless control, sliding mode observer is widely used because of its insensitivity to parameter changes and strong robustness. For unnecessary high frequency chattering and the lack of accuracy in calculation of rotor position and machine speed in the conventional sliding mode observer, a new sliding mode observer based on the new constant velocity reaching law is used to suppress the high frequency chattering of the machine system. A new constant speed reaching law is designed to replace the conventional constant speed reaching law and it is introduced into new sliding mode observer. This method improves the approaching speed of sliding mode and reduces the high frequency chattering of conventional sliding mode observer. In addition, the arctangent function is used to estimate the position of the machine rotor, and the phase compensation for the Angle position error of the machine rotor is carried out. The simulation results show that compared with the Conventional sliding mode observer, the proposed new sliding mode observer is more stable and has better control performance.

This paper presents a sensorless speed control method of permanent magnet synchronous motor (PMSM) applying sliding-mode control theory, to enhance the observation precision and improve robustness of control system. Firstly, an improved full-order sliding mode observer (FSMO) with sigmoid function is gifted to weaken the high-frequency (HF) chattering caused by conventional sliding mode observer (SMO). The quadrature phase-locked loop (PLL) is used to calculate high-precision rotor location and speed, avoiding the use of filter. Then the nonsingular fast terminal sliding mode controller (NFTSMC) in speed controller is introduced to replace traditional proportional integral (PI) controller to improve the dynamic performance of control system. The outcomes verify that the presented control method enhances the overall observation precision, suppresses HF chattering, and increases dynamic and stable state response of PMSM.

This paper proposes a hybrid terminal sliding mode observer based on the nonsingular terminal sliding mode and the high-order sliding mode for the rotor position and speed estimation in the permanent magnet synchronous motor control system. A nonsingular terminal sliding mode manifold is utilized to realize both fast convergence and better tracking precision. Meanwhile, a high-order sliding mode control law is designed to guarantee the stability of the observer and eliminate the chattering. Therefore, the smooth back electromotive force (EMF) signals can be obtained without a low pass filter. According to the back EMF equations, the rotor position and speed can be calculated. Simulation results show that, compared to the conventional sliding mode observer, the hybrid terminal sliding mode observer avoids the phase lag in the back EMF signals, and improves the estimation precision of the rotor position and speed.

A novel fuzzy flux sliding-mode observer for the sensorless speed and position tracking of PMSMs

This brief investigates the use of a new cascaded generalized super-twisting observer (GSTO) for sensorless permanent magnet synchronous motor (PMSM) drives. Specifically, the developed first-stage observer extracts information about internal back-EMF, and then, ensures that the estimation error converges to an arbitrarily small region within a finite time. Meanwhile, the second-stage observer reconstructs the position and speed information synchronously, which can improve the transient performance to a certain extent compared with the arctangent function calculation-based technique. The benefits of the proposed strategy lie in that the cascaded configuration of the two observers minimizes the high-frequency noise of the back-EMF reconstruction system and provides accurate estimations of rotor position and speed. Furthermore, the chattering problem commonly seen in the conventional sliding mode observer (SMO) can be avoided in the presented scheme. Experimental results validate the effectiveness of the proposed methodology.

Most methods to estimate the rotor position of permanent magnetic synchronous motor (PMSM) suffer from the motor parameters, which are difficult to be applied due to the complicated algorithm. This paper presents a sliding mode observer (SMO) to estimate the rotor position of PMSM. The SMO makes use of the error between the estimated current and measured current. And the phase lag, which is caused by the low pass filter, is compensated in a proper way. The convergence of the SMO is guaranteed. A novel estimated speed is used to improve the systematic stability. High performance sensorless drive of the PMSM based on SMO is established and the whole system is simulated by matlab. Simulations show the effect of variation of the torque and speed on the estimated rotor angle. From these experiments, it is found that this method is more robust and easier to be applied.

Mathematical models of PMSM (Permanent Synchronous Magnet Motor) in different reference frames and space vector control technology are researched. Methods of detecting the rotor position of PMSM are analyzed, on the basis of which, a robust SMO (sliding mode observer) with LPF (Low Pass Filter) that is easy for engineering implementation is designed. Parameters of SMO and LPF are coordinated so that the vibration problem of sliding mode is solved. Based on the field-oriented control fundamental and estimated value, the space vector control of sensor-less PMSM is realized.

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.

This study introduces a sensorless control approach for permanent magnet synchronous motors (PMSMs) that employs an Improved Non-Singular Fast Terminal Sliding Mode Controller (IMNFTSMC) and an Improved Non-Singular Fast Terminal Sliding Mode Observer (IMNFTSMO). The IMNFTSMC employs a novel hybrid reaching law and a continuous piecewise square root switching function to achieve faster convergence and effective chattering reduction over the conventional Sliding Mode Controller (SMC). This design successfully replaces two critical components: the discontinuous constant velocity term (a key component of the traditional SMC reaching law that is a primary source of control chattering in PMSM torque regulation) and the high-gain exponential term (which tends to induce overshoot during transient speed adjustments and degrade steady-state control precision). In the IMNFTSMO, a hybrid approach combining linear and non-singular terminal sliding modes eliminates phase lag associated with low-pass filtering in traditional sliding mode observers, improving rotor position and speed estimation accuracy. Stability of both IMNFTSMC and IMNFTSMO is rigorously proven using Lyapunov stability theory.Validation through extensive simulations and hardware experiments, including challenging zero-speed start, speed stepping, and load disturbance tests, confirms the proposed strategy provides improved dynamic response, effective anti-disturbance capability, and high accuracy for rotor position and speed estimation compared to established benchmark methods, demonstrating its feasibility for mid-to-low speed sensorless PMSM drives.