Speed Sensorless Field-oriented Control Research Articles

Open gate fault diagnosis and tolerant for voltage source inverter fed speed sensorless induction motor drive

ABSTRACT This paper presents an effective fault diagnostic and tolerant method for an open-gate fault of a three-phase inverter. The induction motor (IM) drive system is controlled by a speed sensorless indirect rotor field-oriented control (IRFOC). The proposed diagnostic method requires low computation to detect open-gate faults. This method uses a simple direct current technique based on the measured motor currents to detect faulty switch. The fault-tolerant scheme is based on changing the inverter topology from six to four switches to ensure proper operation. In the faulty case, the fault-tolerant technique disconnects the motor phase terminal from the faulty arm of the inverter and connects it to the midpoint of the DC-link via an external switch. The performance of the IM drive is investigated and analysed under normal, faulty and post-fault operations through simulation and experiment. The results demonstrate the effectiveness of the fault diagnostic and tolerant method for retaining almost the normal performance of the IM drive system.

Dynamic Performance of Estimator-based Speed Sensorless Control of Induction Machines Using Extended and Unscented Kalman Filters

Abstract This paper presents an estimator-based speed sensorless field-oriented control (FOC) method for induction machines, where the state estimator is based on a self-contained, non-linear model. This model characterises both the electrical and the mechanical behaviours of the machine and describes them with seven state variables. The state variables are estimated from the measured stator currents and from the known stator voltages by using an estimator algorithm. An important aspect is that one of the state variables is the load torque and, hence, it is also estimated by the estimator. Using this feature, the applied estimator-based speed sensorless control algorithm may be operated adequately besides varying load torque. In this work, two different variants of the control algorithm are developed based on the extended and the unscented Kalman filters (EKF, UKF) as state estimators. The dynamic performance of these variants is tested and compared using experiments and simulations. Results show that the variants have comparable performance in general, but the UKF-based control provides better performance if a stochastically varying load disturbance is present.

Sensorless vector control of PMSM with non-sinusoidal flux using observer based on FEM

Back electromotive force method has been widely used in the position and speed sensorless control of permanent magnet synchronous motors. In this method, it is supposed that the back electromotive forces induced on the stator windings by the rotor permanent magnets are sinusoidal. This assumption causes errors in the estimation of speed and position. In this paper, an observer using the stator winding linkage flux model obtained by using finite element method for position and speed sensorless field-oriented control of permanent magnet motor is proposed. The validity of the proposed method is demonstrated using DS 1104.

A Magnetization Curve Based Stator Resistance and Fuzzy Rotor Resistance Adaptation Technique Suitable for Speed Sensorless Field-oriented Control of Induction Machine

Speed sensorless field-oriented control schemes for induction machines are widely used in modern industries. The parameter variation problem at different operating conditions is the major difficulty for such a scheme. In this article, a model-based technique is developed utilizing the magnetization curve of the machine to estimate simultaneously the stator resistance and magnetizing inductance. In the proposed technique, the stator current axis is taken as the orientation of the d-axis. The estimated stator resistance is independent of rotor speed and, hence, is applicable for speed sensorless schemes. A correct estimation of speed also requires accurate knowledge of rotor resistance for such drives. In the proposed scheme, the rotor resistance variation is also tracked through a fuzzy logic based estimator depending on the stator resistance variation and other input variables. Simulations based on this technique are shown, which are also verified by suitable experimental results.

Speed sensorless field-oriented control of a six-phase saturated model of induction motors drive with online stator resistance estimation using ANFIS

In this paper, a field-oriented control-space vector modulation scheme is presented for a six-phase speed and voltage sensorless saturated model of induction motor drive. The new in this paper is that the saturation model of induction motor is taken into consideration. Also, a simple method is introduced to estimate the motor rotor speed and on line estimation of the stator resistance using adaptive neural fuzzy inference system (ANFIS). Finally, some simulation results are presented to verify the effectiveness and capability of the proposed control scheme.

EKF modeling of field oriented control of six-phase induction motor

This paper deals with using Extended Kalman Filter (EKF) as a powerful tool in estimate of parameters and states of six-phase induction motor (6PIM). The speed-sensorless field-oriented control of 6PIM supplying by SVPWM is used to estimate of parameters in parameter variations. The EKF algorithm estimate stator flux, stator current, and stator resistance by measurement of stator currents of inverter. The estimation algorithms based on the stator fluxes is tested under load variations in the high velocity. The simulation results presented in this paper explain the performance of proposed method in the six-phase induction machine drive.

Speed sensorless field-oriented control of induction motor with interconnected observers: experimental tests on low frequencies benchmark

Field-oriented speed control of induction motors (IMs) without mechanical sensors (speed sensor and load torque sensor) are considered. The methodology is divided into two parts. First, interconnected high-gain observers are designed to estimate the mechanical and magnetic variables from the only measurement of stator current. Secondly, the speed and flux estimation are used by a controller to achieve the speed/flux tracking. The flux regulation problem is simple and the traditional approach is followed by using proportional integral (PI) controller. For the speed-regulation problem, it is stated that flux regulation quickly happens by using a high- gain PI controller to regulate the g-axis current to its reference. Stability analysis based on Lyapunov theory is proved to guarantee the 'observer + controller' stability. To test and validate the controller-observer by considering the sensorless control problem of IM at low frequency, a significant benchmark is implemented. The trajectories of this benchmark are designed to validate the controller and observer under three operating conditions: low speed, high speed and very low speed. Furthermore, robustness tests with respect to parameter variations are given in order to show the performance of the proposed observer-controller scheme.

Speed-Sensorless Estimation for Induction Motors Using Extended Kalman Filters

In this paper, extended-Kalman-filter-based estimation algorithms that could be used in combination with the speed-sensorless field-oriented control and direct-torque control of induction motors (IMs) are developed and implemented experimentally. The algorithms are designed aiming minimum estimation error in both transient and steady state over a wide velocity range, including very low and persistent zero-speed operation. A major challenge at very low and zero speed is the lost coupling effect from the rotor to the stator, which makes the information on rotor variables unobservable on the stator side. As a solution to this problem, in this paper, the load torque and the rotor angular velocity are simultaneously estimated, with the velocity taken into consideration via the equation of motion and not as a constant parameter, which is commonly the case in most past studies. The estimation of load torque, on the other hand, is performed as a constant parameter to account for Coulomb and viscous friction at steady state to improve the estimation performance at very low and zero speed. The estimation algorithms developed based on the rotor and stator fluxes are experimentally tested under challenging variations and reversals of the velocity and load torque (step-type and varying linearly with velocity) over a wide velocity range and at zero speed. In all the scenarios, the current estimation error has remained within a very narrow error band, also yielding acceptable velocity estimation errors, which motivate the use of the developed estimation method in sensorless control of IMs over a wide velocity range and persistent zero-speed operation

A Practical Scheme for Induction Motor Speed Sensorless Field-Oriented Control

This paper deals with a practical scheme of induction motor drive speed sensorless control. It requires the presence of an adaptive flux observer. The speed estimator is based on the induction motor magnetic characteristic slope approximation to the mutual inductance value. Encouraging simulation results have been obtained.

Adaptive sliding-mode observer for speed-sensorless control of induction motors

This paper presents an adaptive sliding-mode observer for the speed-sensorless field-oriented control of induction motors. The observer detects the rotor flux components in the two-phase stationary reference frame by the motor electrical equations. The motor speed is estimated by an additional relation obtained by a Lyapunov function. The analytical development of the sliding observer and the speed estimation algorithm is fully explained. Experimental results are presented, based on a TMS320F240 digital signal processor controller implementation. The system performance with different observer gains and the influence of the motor parameters deviations are shown and discussed.

Adaptive pseudoreduced-order flux observer for speed sensorless field-oriented control of IM

An adaptive pseudoreduced-order flux observer for speed sensorless field-oriented control is presented. In comparison with the adaptive full-order flux observer, the proposed method consumes less computational time and illustrates better speed performance. Simulations and experiments on a 3-hp induction motor verify the validity of the proposed method.

Speed sensorless field-oriented control of induction motor with rotor resistance adaptation

Several field-oriented induction motor drive methods without rotational transducers have been proposed. These methods have a disadvantage that the rotor resistance variation causes an estimation error of the motor speed. Therefore, simultaneous estimation of the motor speed and the rotor resistance is required. This paper presents a method of estimating simultaneously the motor speed and the rotor resistance of an induction motor by superimposing AC components on the field current command. The validity of the proposed method is verified by simulation and experimentation. >