Sebastien Carriere

Six-Phase Induction Machine Model for Electrical Fault Simulation Using the Circuit-Oriented Method

The aim of this paper is to present a six-phase induction machine (6PIM) model based on the so-called circuit-oriented approach suitable for simulation of electrical faults on both stator and rotor sides. This specific model has been developed by using only resistances, inductances, and controlled voltage sources. The coupling effects between both the stator and the rotor have been taken into account by the computation of stator–rotor mutual inductances. The model has been developed under the MATLAB/Simulink environment in order to have a universal tool that is easy to use with any control techniques. With this model, it is possible to simulate any type of electrical faults during the motion by closing or opening corresponding switches. The performances of the model have been validated by comparing simulation and experimental results of a 90-W 14-V 50-Hz two-pole 6PIM operating with different levels of load torque in healthy and faulty modes. Furthermore, this model has been associated to a fault-tolerant speed control method in phase opening occurrences in order to test the model accuracy.

Analysis and control of six-phase induction machines in unbalanced operating situation due to phase opening

This paper deals with speed control of a squirrel cage six-phase induction machine (SC6PIM) in phase opening occurrences. A decoupled model of induction machine with unbalanced structure is given to analyze the phase opening operation of the SC6PIM. In order to reduce torque oscillations created in phase opening events, a fault-tolerant operation method by using indirect rotor field oriented control (IRFOC) technique is proposed and used to control the speed of the SC6PEVI in each faulty operation. The proposed controller will be renewed in each fault situation of machine regarding the number and type of missed phases. Furthermore, in this paper, switching between controllers in some different cases is investigated and real time initial conditions setting for controllers is proposed to minimize the transient problems in switching instant. To evaluate the performance of proposed method, the experimental results are obtained on a small SC6PIM rated at 90 W.

Speed adaptive flux Luenberger observer used in sensorless vector control of an unbalanced six-phase induction machine

In this paper, a speed adaptive flux Luenberger observer is presented for sensorless control of a squirrel cage six phase induction machine (SC6PIM) in healthy and faulty condition. Model of an induction machine in unbalanced operating situation is presented and used to estimate the states of SC6PIM in fault condition by using Luenberger observer and an adaptive speed system. Rotor flux and speed obtained from the observer in unbalanced condition is used in vector control. To ensure the capacity of the observer performance in unbalanced conditions, one, two and three of six phases are lost in experimental test respectively. Also in all tests, maximum value of inertia variation is considered in experimental test as mechanical disturbance.

Online controller modifying of a six-phase induction generator in phase opening occurrences

This study presents field oriented control of a squirrel cage six-phase induction generator (SC6PIG) when a phase fault is detected in order to minimize output power oscillations during phase opening. An unbalanced structure of squirrel cage six-phase induction machine (SC6PIM) has been modeled to analyze healthy and faulty conditions of the machine. According to the unbalanced structure of the machine, a suitable controller is defined in phase missing condition to minimize power oscillations. After fault detection by using a dedicated system, the controller used in healthy condition is switched to a new one regarding to the fault situation. For each controller, appropriate initial conditions are chosen to minimize the transient behavior of switching process between healthy and faulty controllers. The whole proposed system has been implemented on an experimental set up including of a six-phase induction generator coupled with a permanent magnet direct current (dc) motor. Experimental results prove the feasibility and show the improvement of power quality when the controller is modified in phase missing conditions. The experimental results are presented for one phase missing and they can also be obtained for two or three phases missing conditions.

Six-phase induction machine model for simulation and control purposes

The aim of this paper is to develop a six phase induction machine (6PIM) model suitable for the simulation of this machine in any system with control circuits and/or connections to the grid by means of power electronics converters. The circuit-oriented approach has been chosen in order to represent the 6PIM model as a rotating transformer. In fact, a class of universal machine model has been built to be used with simple input electrical parameters such as stator and rotor resistances, self, leakage and mutual inductances. With the model, it is possible to simulate any kind of asymmetry in both stator and rotor sides with or without variations of the machine parameters. A specific six-phase induction machine model, using only resistances, inductances and controlled voltage sources, has been developed. The coupling effects between stator and rotor have been taken into account by the computation of stator-rotor mutual inductances. The performances of the model have been verified by comparison between simulation and experimental results on a 0.09kW-14V-50Hz-2 poles 6PIM working with different levels of the load torque in a healthy and faulty mode.

A Novel Strategy for Sensorless Control Modification of a Six-phase Induction Generator in Faulted Mode

Abstract Due to the limited operations of three-phase machines in open-phase fault conditions, the multiphase induction generators are now introduced in high-performance power generation systems. In the case of six-phase induction generators, the operation with opened phases is associated with torque and consequently power oscillations even in steady state conditions. Previous works have reported different methods to reduce these oscillations but they only deal with sensored control issues. Therefore, this paper deals with on-line modification of a sensorless control system applied to a squirrel cage six-phase induction generator (SC6PIG) when one to three phases of the machine are lost. Designing ten different off-line Luenberger speed observers as well as ten control systems corresponding to the different possible fault types and switching between them as a function of a detection system is proposed in this paper. Furthermore, on-line imposing of the nonzero initial conditions induces a smooth switching between the observers as well as the controllers with minimum associated transient at switching instants. The proposed strategy is tested on a wind turbine simulator driven by a permanent magnet dc motor. The experimental results in healthy and faulty modes assess the validity of the proposed strategy.

Simulation and experimental control of six-phase induction generator for wind turbines

In this paper, simulation and experimental results of a squirrel cage six-phase induction generator (SC6PIG) are presented. The proposed generator, suitable for grid connected multiphase wind energy generating system, is composed of a 24kW SC6PIG prototype connected to a full scale back-to-back converter structure. The aim of this paper is to validate experimentally the simulation model of the whole control system based on the Field Oriented Control (FOC) scheme. Simulation and experimental results are compared for the same generation profiles.

Robust control of a six-phase induction generator under open-phase fault conditions

The use of multiphase machines can increase the reliability of the system since there are still three healthy phases even in faulted mode. Nevertheless, the controllers have to be updated when a fault occurs. In this way, a general control scheme is proposed in such a way to remove the electromagnetic power oscillations for a six-phase induction generator (6PIG) in healthy and up to three opened-phases mode by taking into account the faulted model of the machine to design the control system. In order to validate the capacities of the proposed control strategy, the simulation and experimental results are presented in healthy and faulty conditions modes.

Efficient Field Oriented Control with power losses optimisation of a six-phase induction generator for wind turbines

The aim of this work is to propose an efficient vector control for power losses optimisation of a squirrel cage six-phase induction generator (SC6PIG). This method, suitable for variable speed wind energy conversion system (WECS), allows the increase of the generator efficiency whatever the power operating points. This efficient control method is based on Field Oriented Control (FOC) associated to an electrical power losses minimisation strategy. Experimental tests are realized on a laboratory test bed based on low speed 24 kW SC6PIG. Theoretical results are presented and experimental results for different operating points are compared with a conventional vector control method to prove the effectiveness of the proposed method. Indeed, experimental results shows that the proposed method for light power loads can improve significantly the efficiency of the SC6PIG.

Fault tolerant control of six-phase induction generator for wind turbines

In this paper, simulation and experimental results of a fault tolerant of a squirrel cage six-phase induction generator (SC6PIG) are presented. The proposed generator, suitable for grid connected multiphase wind energy generating system, is composed of a 24kW SC6PIG prototype connected to a full scale back-to-back converter structure. The aim of this paper is to validate experimentally the model of the whole fault tolerant control system based on the Field Oriented Control (FOC) scheme. Simulation and experimental responses are compared for the same generation profiles.