Franck Betin

Modeling and Control of Six-Phase Symmetrical Induction Machine Under Fault Condition Due to Open Phases

This paper introduces a new fault-tolerant operation method for a symmetrical six-phase induction machine (6PIM) when one or several phases are lost. A general decoupled model of the induction machine with up to three open phases is given. This model illustrates the existence of a pulsating torque when phases are opened. Then, a new control method reducing the pulsating torque and the motor losses is proposed in order to improve the drive performances. The proposed method is compared to two other existing techniques. The simulation and experimental results obtained on a dedicated test-rig confirm the validity and the efficiency of the proposed method for a fault-tolerant symmetrical 6PIM drive.

Fuzzy Logic and Sliding-Mode Controls Applied to Six-Phase Induction Machine With Open Phases

The faulted mode of a six-phase induction machine (6PIM) denotes that the motor is working with one or more missing phases. This situation leads to torque oscillations and poor tracking behavior. Therefore, the design of a suitable robust control is a challenging task. In this way, this paper presents the application of fuzzy logic and sliding mode controls in order to obtain a high-accuracy positioning of a 6PIM rotor in both healthy and faulted modes. The two control strategies are completely different from a theoretical point of view, but the final objectives are to remove the drawbacks of the specific fault on interest. The experimental results are obtained on a dedicated setup based on a 6PIM coupled with a variable mechanical load and for which up to three phases can be removed.

Fuzzy logic applied to speed control of a stepping motor drive

Nowadays, thanks to the development of microprocessors, stepping motors are widely used in robotics and in the numerical control of machine tools where they have to perform high-precision positioning operations. Nevertheless, the variations of the mechanical configuration of the drive, which are common to these two applications, can lead to a loss of synchronism for high stepping rates. Moreover, the classical open-loop speed control is weak and a closed-loop control becomes necessary. In this paper, the fuzzy logic principle is applied to control the speed of a stepping motor drive with feedback. An advanced test bed is used in order to evaluate the tracking properties and the robustness capacities of the fuzzy logic controller when variations of the mechanical configuration occur. The experiment has been performed using a low-cost 16 bit microcontroller in order to verify the design performance.

A time-varying sliding surface for robust position control of a DC motor drive

In this paper, a new variable-structure position control law for a DC motor is proposed. The algorithm, based on a time-varying switching line, guarantees the existence of a sliding mode from the beginning of the shaft motion. Indeed, the surface is initially designed to pass through the initial representative point and subsequently moved toward a predetermined desired surface via shifting. By this means, the reaching phase is eliminated and the motor behavior is insensitive to unknown mechanical configuration changes. The algorithm has been tested in simulation and the experiment has been performed using a low-cost 16-bit microcontroller. Then, an advanced test bed is used in order to evaluate the tracking properties and the robustness capacities of the variable-structure control law with variations of the mechanical configuration.

A Web-Based Remote Laboratory for Monitoring and Diagnosis of AC Electrical Machines

This paper deals with the development of a virtual platform for a Web-based remote application dedicated to condition monitoring and fault detection for ac electrical machines. The platform is based on several tools developed by using the LabVIEW software. Various techniques of condition monitoring and diagnosis of electrical and mechanical faults in ac electrical machines have been integrated such as the broken rotor bar, winding short circuit, bearing damage, or static/dynamic eccentricities. The main features are related to a user-friendly interface, a low-maintenance source code, and a standardized database for ac electrical machine diagnosis. The platform architecture, as well as three different test-rig configurations, has been described. The complete system can be controlled in both local and remote modes by using a simple Internet connection. Some remote experiences have been carried out between the University of Picardie “Jules Verne,” Amiens, France, and the University of Bologna, Bologna, Italy, to verify the effectiveness of the proposed system. The direct applications of this original package are based on diagnosis techniques applied to ac electrical machine faults. Some examples of rotor broken bar detection using classical techniques have been presented to show the effectiveness of the proposed platform. Further information will soon be available on the Open European Laboratory on Electrical Machines Web site: www.oelem.org.

Trends in Electrical Machines Control: Samples for Classical, Sensorless, and Fault-Tolerant Techniques

This article has given a significant number of examples of contemporary control techniques for EDs. Of course, many more special machines or specific applications can be investigated as well. However, with IMs, PMSMs, SRMs, and hydrogenerators, the most current industrial applications have been addressed. Most of the presented techniques are not yet fully used in industry and are still under evaluation before diffusion at a large scale in the industry. Therefore, many control techniques, such as FTC schemes, are still under investigation for industrial applications with reliability requirements. Even if there are no standard schemes to implement these modern control techniques, it has been commonly admitted that sensorless and fault-tolerant structures will be used more and more in the future and that they are fully implementable on low-cost digital platforms with a high degree of integration.

Determination of Scaling Factors for Fuzzy Logic Control Using the Sliding-Mode Approach: Application to Control of a DC Machine Drive

In this paper, a new approach to define the optimum values of the scaling factors for a fuzzy logic controller, based on the sliding mode theory, has been proposed. Indeed, these factors are chosen in such a way that the trajectory in the phase plane is always attracted by the main diagonal of the fuzzy matrix and slides on this line. This approach was first tested in simulation to control the position of a permanent-magnet direct-current machine drive and then implemented on a low-cost 16-bit microcontroller. Furthermore, the scaling factors are tuned in function of the distance between the reference and the output in such a way as to cope with the discretization of the lookup table stored in the memory of the microcontroller. This algorithm has been successfully applied on an advanced test bed, which allows mechanical configuration changes

Shaft Positioning for Six-Phase Induction Machines With Open Phases Using Variable Structure Control

In this paper, a new variable structure control law is proposed in order to obtain the shaft positioning of a symmetrical six-phase induction machine when phases are lost and when large variations of inertia occur. The algorithm based on a time-varying switching line guarantees the existence of a sliding mode since the beginning of the shaft motion. Indeed, the surface is first designed to pass through the initial representative point and, subsequently, to move toward a predetermined desired surface via shifting. With this algorithm, the induction machine behavior is exactly the same in healthy or in faulted modes when one or more stator phases are lost and whatever the mechanical shaft configuration is. The capacities of this control technique with a mechanical sensor have been tested in simulation and then validated experimentally on a specific setup.

Torque Ripples Suppression for Six-Phase Induction Motors Under Open Phase Faults

This paper introduces a new disturbance free operation method for six-phase induction motors. The machine is supposed to loss one or more phases and to have a pulsating torque. In order to improve the motor torque, we propose a new control law satisfying a condition required to have a smooth torque. The simulation and experimental results illustrate the validity and the efficiency of the proposed method for disturbance free operation of six-phase induction machines

Low cost two-axis solar tracker with high precision positioning

In this paper, the design of a low cost two-axis solar tracker is introduced. The aim is to obtain a high precision positioning of the cell. The control-board is able to support different control strategy such as classical techniques as PID algorithm or more advanced strategy such as fuzzy logic control (FLC). Using the error signal, the tracking capacities of the proposed approaches can be tested experimentally on the experimental prototype built in our laboratory.