Robust indirect field oriented control of induction generator

The paper presents a novel robust field oriented vector control for induction generators. The proposed controller exploits the concept of indirect field orientation and guarantees asymptotic DC-link voltage regulations when DC-load is constant or slowly varying. An output-feedback linearizing Lyapunov’s based technique is employed for the voltage controller design. Flux subsystem design provides robustness with respect to rotor resistance variations. Decomposition of the voltage and current-flux subsystems, based on the two-time scale separation, allows to use a simple controllers tuning procedure. Results of comparative experimental study with standard indirect field oriented control are presented. It is shown that in contrast to existing solutions designed controller provides system performances stabilization when speed and flux are varying. Experimentally shown that robust field oriented controller ensures robust flux regulation and robust stabilization of the torque current dynamics leading to improved energy efficiency of the electromechanical conversion process. Proposed controller is suitable for energy generation systems with variable speed operation

Indirect Field Oriented Control of Induction Motors is Robustly Globally Stable

Field orientation, in one of its many forms, is an established control method for high dynamic performance AC drives. In particular, for induction motors, indirect fieldoriented control is a simple and highly reliable scheme which has become the de facto industry standard. In spite of its widespread popularity no rigorous stability proof for this controller was available in the literature. In a recent paper (Ortega et al, 1995) [Ortega, R., D. Taoutaou, R. Rabinovici and J. P. Vilain (1995). On field oriented and passivity-based control of induction motors: downward compatibility. In Proc. IFAC NOLCOS Conf., Tahoe City, CA.] we have shown that, in speed regulation tasks with constant load torque and current-fed machines, indirect field-oriented control is globally asymptotically stable provided the motor rotor resistance is exactly known. It is well known that this parameter is subject to significant changes during the machine operation, hence the question of the robustness of this stability result remained to be established. In this paper we provide some answers to this question. First, we use basic input-output theory to derive sufficient conditions on the motor and controller parameters for global boundedness of all solutions. Then, we give necessary and sufficient conditions for the uniqueness of the equilibrium point of the (nonlinear) closed loop, which interestingly enough allows for a 200% error in the rotor resistance estimate. Finally, we give conditions on the motor and controller parameters, and the speed and rotor flux norm reference values that insure (global or local) asymptotic stability or instability of the equilibrium. This analysis is based on a nonlinear change of coordinates and classical Lyapunov stability theory

Takagi-Sugeno fuzzy perpose as speed controller in indirect field oriented control of induction motor drive

This paper deal with the problem in speed controller for Indirect Field Oriented Control of Induction Motor. The problem cause decrease performance of Induction Motor where it widely used in high-performance applications. In order decrease the fault of speed induction motor, Takagi- Sugeno type Fuzzy logic control is used as the speed controller. For this, a model of indirect field oriented control of induction motor is built and simulating using MATLAB simulink. Secondly, error of speed and derivative error as the input and change of torque command as the output for speed control is applied in simulation. Lastly, from the simulation result overshoot is zero persent, rise time is 0.4s and settling time is 0.4s. The important data is steady state error is 0.01 percent show that the speed can follow reference speed. From that simulation result illustrate the effectiveness of the proposed approach

A simple maximum power point tracking based control strategy applied to a variable speed squirrel cage induction generator

This paper presents a comprehensive modelling and control study of a variable speed wind energy conversion system based on a squirrel-cage induction generator (SCIG). The mathematical model of the SCIG is derived in Park frame along with the indirect field oriented control (IFOC) scheme based on a proportional and integral speed controller. A simple maximum power point tracking strategy is used to determine the optimal speed under variable wind speed conditions which is then used as the reference in the IFOC scheme. Power flow between the supply and the inverter is regulated via simultaneous control of the active and reactive currents of the grid and the DC link voltage. The simulation results show that the proposed control technique is able to maximise the energy extracted from the wind during the simulation scenarios considered. The results also demonstrate good transient response characteristics in the decoupled real and reactive powers.Peer reviewedFinal Accepted Versio

Indirect Rotor Field Oriented Control of Induction Motor With Rotor Time Constant Estimation

This thesis presents an estimation technique of the inverse rotor time constant for Indirect Rotor Field Oriented Control (IRFOC) induction motor application. In this estimation technique two different equations are used to estimate the rotor flux in the stator reference frame. One of the equations is a function of the rotor time constant, rotor angular velocity and the stator currents, and the other equation is a function of measured stator currents and voltages. The equation that uses the voltage and the current signals of the stator serves as reference model, while the other equation works as an adjustable model with respect to the variation of the rotor time constant. Measurements of two phases of the current, and speed using an optical encoder are required in this estimation technique. The stator phase voltages are estimated from the DC bus voltage and the switching commands signals with compensation of the dead time effect. Field oriented control of induction motor is gaining wides acceptance in high performance AC motor drive applications. Field oriented control, in its both forms as a direct or indirect, gives the AC motor dynamics that are equivalent to that of a DC motor. However, direct and indirect field oriented control suffer from specific theoretical and practical problems. The approach of direct field oriented control with Hall sensors for flux sensing has limitations governed by the physical structure of the machine itself. On the other hand, the approach of indirect field oriented control of induction machines is highly dependent on the rotor parameters, which are not easily accessible for measurements except for the rotor speed. In a DC motor, spatial relationship of the torque and flux is maintained by the physical construction of the motor armature and field circuits. However, in an induction motor such spatial relationship does not maintain as such machine has usually a single terminal where electric power is supplied. Therefore, such relationship is maintained by external control methods. In a basic IRFOC of an induction motor, speed and phase currents are sensed in order to control the stator current vector such a way so it can be resolved into two components, one is to control the rotor flux and the other to control the motor torque. Successful decomposition of stator current vector into these two components requires the knowledge of the instantaneous position, of the rotor flux vector. Since the position of the rotor flux vector is estimated in an IRFOC scheme, and is dependent on the motor model (more specifically the rotor parameters), these parameters must be obtained accurately and match the motor parameters at all times. Unfortunately, rotor parameters vary and are not easily accessible for measurements. Therefore, this uncertainty about the rotor flux vector position degrades the dynamic operation of the drive.Enormous efforts have been made to improve IRFOC complicated hardware and software in order to coixpensate for such imperfection. Hence, this work focuses on the Indirect Rotor Field Oriented Control of induction motors with estimation of the rotor time constant. A simple yet effective rotor time constant identification method is presented and used for updating the slip calculator used by the IRFOC algorithms. A complete simulation model of an induction motor and IRFOC scheme is presented and tested using SIMULINWMATLAB, and experimentally implemented on a DSP Board (MCK243j without any need for voltage phase sensors. Simulation and experimental results were presented and compared to verify the validity of the proposed estimator for different operating conditions

Independent Control of Two Induction Motors Fed by a Five Legs PWM Inverter for Electric Vehicles

International audienceThis paper deals with the implementation of an independent control of two induction motors fed by five legs PWM inverter. In this context, two Pulse Width Modulation techniques are presented in order to be included in the indirect field oriented control algoritm. Experiments and simulation are carried-out, on an induction motor drive, to show that the developed independ control of five legs inverter is effective and provides a simple configuration with high performance in terms of speed and torque responses

Electromechanical systems with transient high power response operating from a resonant AC link

The combination of an inherently robust asynchronous (induction) electrical machine with the rapid control of energy provided by a high frequency resonant AC link enables the efficient management of higher power levels with greater versatility. This could have a variety of applications from launch vehicles to all-electric automobiles. These types of systems utilize a machine which is operated by independent control of both the voltage and frequency. This is made possible by using an indirect field-oriented control method which allows instantaneous torque control in all four operating quadrants. Incorporating the AC link allows the converter in these systems to switch at the zero crossing of every half cycle of the AC waveform. This zero loss switching of the link allows rapid energy variations to be achieved without the usual frequency proportional switching loss. Several field-oriented control systems were developed by LeRC and General Dynamics Space Systems Division under contract to NASA. A description of a single motor, electromechanical actuation system is presented. Then, focus is on a conceptual design for an AC electric vehicle. This design incorporates an induction motor/generator together with a flywheel for peak energy storage. System operation and implications along with the associated circuitry are addressed. Such a system would greatly improve all-electric vehicle ranges over the Federal Urban Driving Cycle (FUD)

A Control Reconfiguration Strategy for Post-Sensor FTC in Induction Motor-Based EVs

International audienceThis paper deals with experimental validation of a reconfiguration strategy for sensor fault-tolerant control (FTC) in induction-motor-based electric vehicles (EVs). The proposed active FTC system is illustrated using two control techniques: indirect field-oriented control (IFOC) in the case of healthy sensors and speed control with slip regulation (SCSR) in the case of failed current sensors. The main objective behind the reconfiguration strategy is to achieve a short and smooth transition when switching from a controller using a healthy sensor to another sensorless controller in the case of a sensor failure. The proposed FTC approach performances are experimentally evaluated on a 7.5-kW induction motor drive