Cristiane Cauduro Gastaldini

Sensorless Sliding-Mode Rotor Speed Observer of Induction Machines Based on Magnetizing Current Estimation

This paper presents a rotor speed observer for induction-machine drives based on a sliding-mode approach and magnetizing current estimation. The back electromotive force (EMF) is calculated from the stator current and the stator voltage signals. The magnetizing currents are obtained from the back EMF. A theorem which gives the rotor speed estimate in the continuous-time domain is formulated using the magnetizing current estimation. The stability analysis is achieved based on the Lyapunov approach. Moreover, the discrete-time approach of the method is discussed, and a theorem for the discrete-time implementation is proposed. The limits that ensure the system stability for the switching gains and for the observer gain are discussed. This paper shows that the limits for the gains of the discrete-time algorithm are different from the limits for the gains of the continuous-time algorithm. Simulation results are presented to validate the theoretical analysis. In addition, experimental results based on a fixed-point digital signal processor (DSP) platform (DSP TMS320F2812) demonstrate the performance of the proposed scheme.

Electrical parameters identification of hermetic Refrigeration compressors with Single-Phase Induction Machines using RLS algorithm

This paper presents a methodology for parameter identification of a Single-Phase Induction Machine (SPIM) of an air conditioning compressor. From the machine model two classical Recursive Least Square (RLS) algorithms are applied at qd axes based on current measurements with standstill rotor. The identification is achieved with standstill rotor due the fact that this methodology allow to be implemented in hermetic refrigeration compressor driven by SPIM. Then, the identified parameters can improve the performance of the Field Oriented Control (FOC) and sensorless techniques used in these systems. Furthermore, the correct parameters of Single-Phase Induction Machine allow a better representation of dynamic simulation behavior of compressor driven by SPIM. Experimental results are presented to provide the effectiveness of the method.

An adaptive feedback linearization control for induction motor

An adaptive state feedback linearizing control (AFLC) is designed for a fifth order model of a three-phase induction motor which includes both electrical and mechanical dynamics. The control algorithm contains an adaptive scheme of feedback linearization control (FLC) to improve robustness against of model parameters variation of induction motor servomechanism. In order to provide an estimated rotor speed for the control system, a model reference adaptive system (MRAS) algorithm based on reactive power was applied. This estimation passes through a Kalman filter, which is also used for the torque estimation. Experimental results are provided to evaluate control schemes performance comparing AFLC scheme with FLC control scheme.

Simple PWM approach for modulation of three-leg inverters driving two-phase symmetrical and asymmetrical machines

This paper presents a simple PWM approach for modulation of three-leg inverters driving two-phase induction machines. The main contribution of this paper is the development of a simple PWM modulation method to generate symmetrical and asymmetrical voltages suitable to fed two-phase induction machines. It is demonstrated that the amplitudes of line voltages can to vary from zero until 0.707 pu of DC-link voltage for symmetrical voltages, while one of the voltages can overcome 0.707 pu of DC-link voltage in the asymmetrical case. The results obtained with the proposed modulation technique are similar to those obtained with space vector modulation, however, the implementation of the proposed modulation technique is much more simple than the implementation of space vector modulation. Experimental results that validate the theoretical analysis are presented and they demonstrate the good performance and simplicity of the proposed modulation method.

Discrete-time sliding mode approach for speed estimation of symmetrical and asymmetrical induction machines

This paper presents and analysis a rotor speed estimator for symmetrical and asymmetrical induction machines. The proposed scheme is based on discrete-time formulation of the sliding mode observer. The method is suitable to close-loop sensorless control of induction machines. The stability and parameter convergence of the proposed method are analyzed by using discrete-time likelihood Lyapunov. Experimental results based on DSP platform (TMS320F2812) are presented and they demonstrate the good performance of the proposed sensorless control scheme for symmetrical and asymmetrical induction motor drives.

Decoupling and sensorless vector control scheme for single-phase induction motor drives

Vector control has improved the performance and energy efficiency in SPIM drives. However, high current and torque pulsations are produced by winding asymmetry of SPIM. This paper proposes a decoupling scheme to reduce the current and torque pulsations and improve the performance of vector control. A stator current observer is used to estimate the coupling signals, which are compensated by control law. This method is an alternative to improve the performance of single-phase induction motor used in hermetic refrigeration systems. The thermal efficiency of refrigeration system can be improved by the variable speed operation and the advantages of robustness and low-cost of single-phase induction motor can be maintained.

Discrete-time sliding mode speed observer for induction machine drives

This paper addresses the rotor speed estimation problem of induction machine drives. A scheme based on discrete-time formulation of the Sliding Mode Observer is proposed and analyzed. The method is suitable to close-loop sensorless control of induction machines. The stability analysis and parameter convergence of the proposed method is presented. Simulation and experimental results based on DSP platform (TMS320F2812) demonstrate the good performance of the proposed sensorless control scheme.

A comparison of speed-sensorless induction motor control with torque compensation

This paper compares two indirect field oriented control approaches of speed sensorless MRAS schemes. The first scheme is a feedback linearization control of an induction motor including proportional integral compensation. The second is a modify feedback linearization scheme, where the current control is composed only by proportional integral controllers. Experimental analyses of the feedback linearization control demonstrate that it requires a larger computation effort as well as it has high sensitivity to model parameters variation. In order to overcome these limitations, this paper proposes a modified scheme based on two PI controllers to generate the stator drive voltage. Simulation and experimental results, in DSP TMS 320F2812 based platform, are provided to evaluate both control schemes performance.

Feedback linearization control with sliding mode speed observer for three-phase induction machines

This paper addresses the problem of controlling a three-phase induction motor without speed measurements. A nonlinear feedback linearization control was designed for a fifth order induction motor model including electrical and mechanical dynamics. The proposed control scheme, which is an indirect field oriented control technique (IFOC) based on feedback linearization control (FLC), is made up of flux-speed controllers. It is inserted on these controllers additional terms designed according discrete time Lyapunov functions to ensure the flux alignment. In order to provide an estimated rotor speed for the control system, it is used a slide mode observer algorithm. Some experimental results with TMS 320F2812 DSP are provided to verify the proposed system performance in a low speed conditions.

Electrical disturbance compensation algorithm applied to three-phase induction motors

One of the ways to control the dynamic of an induction motor is using Field Oriented Control (FOC) or Vector Control. But in this case we can remark electrical disturbance represented by coupling between direct and quadrature currents of induction motor and parameters uncertainties. This disturbance degradate the control law when the rotor speed grows. In this paper we proposed a algorithm to improve the performance of vector control. The algorithm is based on Lyapunovs Direct Method and it is used to estimate this disturbance and eliminated him. Simulation results are shown to validate the proposed technical.