Assessment of a Universal Reconfiguration-less Control Approach in Open-Phase Fault Operation for Multiphase Drives

Multiphase drives have been important in particular industry applications where reliability is a desired goal. The main reason for this is their inherent fault tolerance. Di erent nonlinear controllers that do not include modulation stages, like direct torque control (DTC) or model-based predictive control (MPC), have been used in recent times to govern these complex systems, including mandatory control reconfiguration to guarantee the fault tolerance characteristic. A new reconfiguration-less approach based on virtual voltage vectors (VVs) was recently proposed for MPC, providing a natural healthy and faulty closed-loop regulation of a particular asymmetrical six-phase drive. This work validates the interest in the reconfiguration-less approach for direct controllers and multiphase drives

Open-Phase Fault Operation on Multiphase Induction Motor Drives

Multiphase machines have been recognized in the last few years like an attractive alternative to conventional three-phase ones. This is due to their usefulness in a niche of applications where the reduction in the total power per phase and, mainly, the high overall system reliability and the ability of using the multiphase machine in faulty conditions are required. Electric vehicle and railway traction, all-electric ships, more-electric aircraft or wind power generation systems are examples of up-to-date real applications using multiphase machines, most of them taking advantage of the ability of continuing the operation in faulty conditions. Between the available multiphase machines, symmetrical five-phase induction machines are probably one of the most frequently considered multiphase machines in recent research. However, other multiphase machines have also been used in the last few years due to the development of more powerful microprocessors. This chapter analyzes the behavior of generic n-phase machines (being n any odd number higher than 3) in faulty operation (considering the most common faulty operation, i.e. the open-phase fault). The obtained results will be then particularized to the 5-phase case, where some simulation and experimental results will be presented to show the behavior of the entire system in healthy and faulty conditions. The chapter will be organized as follows: First, the different faults in a multiphase machine are analyzed. Fault conditions are detailed and explained, and the interest of a multiphase machine in the management of faults is stated. The effect of the open-phase fault operation in the machine model is then studied. A generic n-phase machine is considered, being n any odd number greater than three. The analysis is afterwards particularized to the 5-phase machine, where the open-phase fault condition is managed using different control methods and the obtained results are compared. Finally, the conclusions are presented in the last section of the chapter

Impact of post-fault flux adaptation on six-phase induction motor drives with parallel converters

The redundancy of multiphase drives provides an inherent fault-tolerant capability that is appreciated in applications with a complicated corrective maintenance or safety-critical requirements. Fault restrictions however force the system to be reconfigured to operate in a smooth and efficient manner. Previous works have been focused on the optimization of current waveforms to generate an undisturbed operation but still maintaining the pre-fault rated flux settings. This work shows that efficient controllers can improve the post-fault performance in six-phase induction machines supplied by parallel- connected converters if offline optimization is used to obtain a variable reference flux. Theoretical and experimental results confirm that the proposed flux adaptation method provides higher torque/power capability, lower degree of imbalance in the current sharing between windings and efficiency improvementMinisterio de Ciencia e Innovación ENE2014-52536-C2-1-R DPI2013- 44278-RJunta de Andalucía P11-TEP-755

Open-Phase Fault Operation of 5-Phase Induction Motor Drives using DTC Techniques

Direct torque control (DTC) is extensively used in conventional three-phase drives as an alternative to field-oriented control methods. The standard DTC technique was originally designed to regulate two independent variables using hysteresis controllers. Recent works have extended the procedure for five-phase drives in healthy operation accounting for the additional degrees of freedom. Although one of the main advantages of multiphase machines is the ability to continue the operation in faulty conditions, the utility of DTC after the appearance of a fault has not been covered in the literature yet. This paper analyses the operation of a five-phase induction motor drive in faulty situation using a DTC controller. An open-phase fault condition is considered, and simulation results are provided to study the performance of the drive, comparing with the behavior during healthy state

Application of DSP in Power Conversion Systems — A Practical Approach for Multiphase Drives

Digital Signal Processing is not a recent research field, but has become a powerful technology to solve engineering problems in the last few decades due to the introduction by Texas Instruments in 1982 of the Digital Signal Processor. Fast digital signal processors have quickly become a cornerstone of high-performance electrical drives, where power electronic conversion systems have heavy online computation burdens and must be controlled using complex control algorithms. In this sense, multiphase drives represent a particularly interesting case of study, where the computational cost highly increases with each extra phase. This technology has been recognized in recent times as an attractive electrical drive due to its usefulness in traction, more-electric aircraft applications and wind power generation systems. However, the complexity of the required control algorithms and signal processing techniques notably increases in relation with conventional three-phase drives. This chapter makes a revision of the necessities of a high-performance multiphase drive from the digital signal processing perspective. One of the most powerful Texas Instruments’ digital signal processor (TMS320F28335) is used, and specific control algorithms, electronic circuits and acquisition processing methods are designed, implemented and analyzed to show its interest in the development of a high-performance multiphase drive

Multiphase Current Imbalance Localization Method Applied to Natural Fault- Tolerant Strategies

Multiphase machines are interesting options for high-reliability applications due to their inherent fault tolerance against open-circuit faults (OCFs). Moreover, if the regulation of the x-y currents is realized in open-loop mode using virtual voltage vectors (VVs), the mandatory post-fault control reconfiguration is avoided. The new reconfiguration-less approach was recently defined as a natural/passive fault-tolerant strategy, offering good prospects for industry applications. This work extends the idea to the fault detection (FD) procedure and suggests new settings for the current imbalance localization (CIL) method. The proposal is based on the vector space decomposition (VSD) approach that allows the joint detection of OCFs and stator resistances dissymmetry (RDs). Experimental results in a five-phase induction motor (IM) drive using VVs confirm the viability of the technique

Fault-tolerant Operation of Six-phase Energy Conversion Systems with Parallel Machine-side Converters

The fault tolerance provided by multiphase machines is one of the most attractive features for industry applications where a high degree of reliability is required. Aiming to take advantage of such postfault operating capability, some newly designed full-power energy conversion systems are selecting machines with more than three phases. Although the use of parallel converters is usual in high-power three-phase electrical drives, the fault tolerance of multiphase machines has been mainly considered with single supply from a multiphase converter. This study addresses the fault-tolerant capability of six-phase energy conversion systems supplied with parallel converters, deriving the current references and control strategy that need to be utilized to maximize torque/power production. Experimental results show that it is possible to increase the postfault rating of the system if some degree of imbalance in the current sharing between the two sets of threephase windings is permitted.Ministerio de Ciencia e Innovación ENE2014-52536-C2–1-R DPI2013-44278-RJunta de Andalucía P11-TEP-755

Comparative Study of DTC and RFOC Methods for the Open-Phase Fault Operation of a 5-Phase Induction Motor Drive

Direct Torque Control (DTC) technique has been applied in recent times in high performance five-phase induction motor drives during the normal operation of the system. The use of DTC in the multiphase area is far from becoming a reality because it has not been used in competitive multiphase applications where the fault operation needs to be considered. The authors have successfully tested the ability of DTC controllers to manage the open-phase fault operation in a five-phase induction motor drive. However, the conclusion of the mentioned study must be completed comparing the obtained results with other mature alternatives based on field oriented controllers. This paper focuses on the comparative analysis of DTC and Rotor Field Oriented Control (RFOC) when an open-phase fault appears in the five-phase induction motor drive. Simulation results are provided to compare the performance of the system using these control alternatives

Enzimas salivales y enfermedad periodontal

Objetivos: Las enfermedades que producen daño tisular producen la liberación de diferentes enzimas relacionadas con la muerte y destrucción celular, como son la aspartato y alanino aminotransferasa (AST, ALT), lactato dehidrogenasa (LDH), creatinin kinasa (CK), alcalina y ácida (ALP, ACP) y gamma glutamil transferasa (GGT). Al tratarse la enfermedad periodontal (EP) de un proceso inflamatorio con afectación de la encía y periodonto, parece lógico pensar que la actividad enzimática debe reflejar los cambios metabólicos secundarios a esta reacción inflamatoria. Diseño del estudio: En este artículo examinamos la actividad de CK, LDH, AST, ALT, GGT, ALP y ACP en la saliva de pacientes con EP, antes y después del tratamiento periodontal (grupo experimental'30 muestras) así como en la saliva de pacientes sin enfermedad periodontal (grupo control'20 muestras). La EP se diagnosticó en base a parámetros clínicos (índice gingival'GI, sangrado al sondaje-BOP y profundidad al sondaje-PD). Todos los pacientes con enfermedad periodontal recibieron tratamiento convencional de la misma. Se registró la actividad enzimática en todos los pacientes y se cuantificó por espectrofotometría Resultados: Se observó un aumento estadísticamente significativo en la actividad de CK, LDH, AST, ALT; GGT, ALP y ACP en la saliva de los pacientes con enfermedad periodontal en relación a los resultados obtenidos en el grupo control. Se detectó una correlación positiva entre la actividad de las enzimas salivales examinadas y el valor del GI. Después del tratamiento periodontal convencional la actividad de estas enzimas salivales disminuyó significativamente. Conclusiones: Basándonos en estos resultados. Podemos concluir que la actividad de estas enzimas puede ser útil en el diagnóstico y evaluación del tratamiento de la EP.Background: Host responses to periodontal disease include the production of different enzymes that are released by stromal, epithelial or inflammatory cells. There are important enzymes associated with cell injury and cell death like: aspartate and alanine aminotransferase (AST, ALT), lactate dehydrogenase (LDH), creatine cinase (CK), alkaline and acidic phosphatase (ALP, ACP), gama glutamil transferase (GGT). Changes in enzymatic activity reflect metabolic changes in the gingiva and periodontium in inflammation. Design of Study: In this paper we have examined the activity of CK, LDH, AST, ALT, GGT, ALP and ACP in saliva from patients with periodontal disease before and after periodontal treatment (experimental group ' 30 samples) and in saliva from healthy patients (control group ' 20 samples). Periodontal disease was determined based on clinical paIndexed desrameters (gingival index (GI), bleeding on probing (BOP), probing depth (PD)). Patients with periodontal disease were under conventional periodontal treatment. Results: Obtained results were shown statistically significant increases of activity of CK, LDH, AST, ALT, GGT, ALP, ACP in saliva from patients with periodontal disease in relation to control group. There is positive correlation between the activity of examined salivary enzymes and value of the gingival index. After conventional periodontal therapy the activity of all salivary enzymes was significantly decreased. Conclusions: Based on these results, it can be assume that activity of these enzymes in saliva, as biochemical markers for periodontal tissue damage, may be useful in diagnosis, prognosis and evaluation of therapy effects in periodontal disease

Fast finite-state predictive current control of electric drives

This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/This work presents a novel optimization method for the implementation of finite-state modelbased predictive current controllers in electrical drives. The proposal avoids the usual exhaustive search to find the control action, reducing the computational burden. The method is based on physical considerations of the power converter voltage vectors and is easy to implement on digital signal processors. The proposal is applied to a five-phase induction machine. Experimental results are compared with those obtained by a standard model-based controller, showing the feasibility of the proposal and the improvements in terms of sampling time reduction and control accuracy