Sliding Mode Current Observer Research Articles

Research on Position Sensorless Control of RDT Motor Based on Improved SMO with Continuous Hyperbolic Tangent Function and Improved Feedforward PLL

With the increasing use of electric propulsion ships, the emergence of the shaftless rim-driven thruster (RDT) as a revolutionary integrated motor thruster is gradually becoming an important development direction for green ships. The shaftless structure of RDTs leads to their dependence on position sensorless control techniques. In this study, a novel control algorithm using a composite sliding mode observer (SMO) with a modified feed-forward phase-locked loop (PLL) is presented for achieving high accuracy position and speed control of shaftless RDT motors. The deviation between the observed and actual currents is exploited to develop a current SMO to extract back electromotive force (back-EMF) errors. On this basis, a back-EMF observer is established to achieve accurate estimation of the back-EMF. The basic structure of the PLL was modified and incorporates a speed feedforward mechanism, which enhances the performance of rotor position estimation and facilitates bidirectional rotation. The stability of the algorithm has been verified in Matlab/Simulink for a range of steady-state, dynamic, and ship propeller loading conditions. Remarkably, the control algorithm boasts an impressive adjustment time of approximately 0.006 s and its position estimation error may be as low as 0.03 rad. Simulation results highlight the performance of the algorithm to achieve bidirectional rotation, while exhibiting fast convergence, minimal vibration, exceptional control accuracy, and robustness.

Sensorless speed control of 6/4-pole switched reluctance motor with ANFIS and fuzzy-PID-based hybrid observer

This paper presents the sensorless speed control of 6/4 pole SRM drive based on hybrid observer (HO). It consists of two modes, i.e., current sliding mode observer is for high speed and flux linkage sliding mode observer is for low speed control. A nonlinear model of SRM is simulated in MATLAB/Simulink. HO is simulated from low to high speed level, and also estimated position and speed errors are optimized with ANFIS and fuzzy-PID methods. Experimental validation is taken for three set speeds, and measured results are compared with the simulated results. Overall speed and position estimated error, electromagnetic torque ripple output results are compared, and its values are tabulated at the end. This observer has the advantages of high-precision speed control without any additional hardware, and also performance has improved.

A New Adaptive SMO for Speed Estimation of Sensorless Induction Motor Drives at Zero and Very Low Frequencies

A speed control of sensorless induction motor (IM) drives at zero and very low frequencies is designed in this paper. A new adaptive sliding mode observer (SMO) to estimate the stator current, rotor flux, and rotor speed is proposed. To improve the robustness and accuracy of an adaptive SMO during very low frequency operation, the sliding mode flux observer uses independent gains of the correction terms. The gains of current and rotor flux SMOs are designed using Lyapunov stability theory to guarantee the stability and fast convergence of the estimated variables. A Lyapunov function candidate utilizing the error of rotor fluxes and speed estimation error is synthesized for speed estimation. Detailed simulations and experiments are given showing the operation of the sensorless speed control at very low frequency. The results prove the accuracy and robustness of the proposed adaptive SMO. Also, comparison results with the state-of-the-art methods prove that the proposed method shows excellent transient and steady-state speed estimation, particularly at very low and zero frequency operations.

Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems.

This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

DSP-Based Sensorless Speed Control of a Permanent Magnet Synchronous Motor using Sliding Mode Current Observer

In this paper, experimental results of 3-phase permanent magnet synchronous motor (PMSM) sensorless speed control are presented. To estimate the rotor position, a sliding mode current observer (SMCO) was implemented. This observer estimates the back emfs of the motor in the stationary reference frame using only the measured voltages and currents of the motor. These emfs were utilized to obtain the rotor position. The speed of the motor was calculated by differentiating the rotor position angle. The stability of the proposed SMCO was verified using Lyapunov method to determine the observer gain. The saturation function was adopted in order to reduce the chattering phenomenon caused by the SMCO. A vector control method was employed to achieve the sensorless drive system. The control application was developed in C/C++ language and implemented using the Texas Instruments TMS320LF2812 digital signal processor (DSP). This new processor enables intelligent control for motors. We used to test the drive the MCK2812 which is a professional development kit available from Technosoft Company. The theoretical finding is validated with experimental results that show the effectiveness of the real-time implementation.

30kW IPMSM Phase Current Sliding Mode Observer Control

A 30kW interpolation permanent magnet synchronous motor(IPMSM) for electric vehicles is discussed in this paper, the phase current sliding mode observer control strategy is proposed, by means of adjusting the current error between the target and practical phase current of the motor, and according which the designed current sliding mode observer output voltage. An improved index reaching law control method is shown, the switching gain can always maintain smaller and converges to zero when imported time-varying factors to it. The inherent shortcomings of the index reaching law can be overcome by using integral sliding surface with integral separation and importing the boundary layer method, effectively weakening the system buffeting.

High-Performance Sensorless Control of PMSM Based on Sliding Mode Current Observer

The sensorless vector control system of permanent magnet synchronous motor (PMSM) is a system with uncertainty and external disturbance. According to sliding mode control theory, this paper realized robust control of the uncertainty and external interference by use of the equivalent control matched with switching control. Meanwhile, in order to eliminate the adverse effect produced by the chattering of the sliding mode, this paper adopts the saturation function of quasi-sliding mode instead of the traditional sign function. Furthermore, the exponential reaching law is used to further weaken the chattering and to ensure the rapidity of the system. Simulation and experimentation show that this control method has good dynamic and static performance.

Sliding Mode Current Observer for Sensorless Vector Control of PMSM

The sensorless control system of permanent magnet synchronous motor is a system with an uncertainty and external disturbance. This paper uses the control law of equivalent control matched with switching control according to the theory of variable structure with sliding mode control, and achieves a robust control of the uncertainty and external disturbance. In order to eliminate the adverse effect caused by the chattering of the sliding mode, a saturation function of the quasi-sliding mode is used instead of the traditional sign function. Simulations and experiments prove that this control technology has a nicer dynamic and static performance.

Very low speed and zero speed estimations of sensorless induction motor drives

Recently, speed sensorless control of induction motor drives received great attention to avoid the different problems associated with direct speed sensors. However, low speed operation with robustness against parameter variations remains an area of research for sensorless systems. Stator resistance is of utmost importance for good operation of speed sensorless systems in low speed region. In this paper, a sliding mode current observer for an induction motor is presented. An estimation algorithm based on this observer in conjunction with Popov's hyper-stability theory is proposed to calculate the speed and stator resistance independently. The proposed speed observer with parallel stator resistance identification is first verified by simulation. Experimental results are included as well as to demonstrate the good performance of the proposed observer and estimation algorithms at very low and zero speeds.