International Conference on Renewable Energies and Power Quality (ICREPQ’17) Malaga (Spain), 4 th to 6 th April, 2017 Renewable Energy and Power Quality Journal (RE&PQJ) ISSN 2172-038 X, No.15 April 2017 An Open-phase Fault Detection Method for Six-phase Induction Motor Drives N. Rios-Garcia 1 , M.J. Duran 1 , I. Gonzalez-Prieto 1 , C. Martin 2 and F. Barrero 2 1 Department of Electrical Engineering E.T.S.I.I., Malaga University 29071 Malaga (Spain) e-mail: nrg@uma.es, mjduran@uma.es, igp@uma.es 2 Department of Electronic Engineering E.T.S.I, Sevilla University 41092 Seville (Spain) e-mail: cmartin15@us.es, fbarrero@us.es Abstract. Induction machines (IM) with multiple sets of three-phase windings are a real alternative in safety- critical applications due to their inherent redundancy and extra number of freedom degrees. These properties can be used to develop a fault-tolerant system without extra hardware. The fault detection is mandatory in the creation of a fault tolerant system. Since, the fault localization allows to adapt the control scheme of this anomalous mode of operation. Nowadays, open-phase faults (OPFs) and six-phase IMs are hot topics in the literature of fault-tolerant drives. Thus, this paper presents an open-phase fault detection method for a six-phase IM drive. The detection method is based on the vector space decomposition (VSD), taking the components of the secondary orthogonal subspace to localize the open-phase fault. The goodness of the proposed method is validated with simulation results. Key words: Multiphase motor drives, open-phase fault, fault detection, fault localization. 1. Introduction Multiphase machines and drives have different advantages over standard three-phase machines [1-3]. Some of these advantages are: a certain degree of fault tolerance, a better distribution of power or a lower torque ripple. However, the most convincing one for the industry is the capability to provide fault tolerance with no extra hardware. This feature is especially valuable in safety-critical applications such as aerospace or naval drives [4-12]. In such cases, the inherent redundancy provided by multiphase systems allows the fault tolerant operation of the drive. However, the implemented control system must be able to manage the occurrence of the fault to provide a smooth post-fault operation. The fault management in a drive can be classified in three stages: fault detection FD [13-17], fault isolation FI [18- 19] and implementation of a fault tolerant control (FTC) [20-25]. The implementation of these three stages in the system is necessary to ensure a suitable operation and to protect the system in post-fault situation. The recent studies have been focused mainly in the development of FD methods and FTC strategies. Since, the fault detection is usually combined with a post-fault control [14,17]. For this reason, the requirements of an ideal detection method are the following: R1. A short detection time. R2. Capability to localize the fault. R3. Use of non-invasive techniques and avoid additional hardware. R4. Avoid complex approaches with an elevated computational cost. R5. Be independent of the machine parameter, control strategy and operation condition. Even though there are some FD methods in the multiphase drives literature, none of these methods comply with the aforementioned conditions [13]. [14] proposes a detection method of dissymmetry in the stator resistance for a seven-phase IM. However, this method is dependent on the control strategy (R5 is not satisfied). R3 requirement is violated in [15-16], where additional voltage measurements are necessary to detect inter-turn short circuit. An observer-based fault detection method is presented in [17] together with a fault-tolerant finite control. This developed observer has an important computational cost and it is dependent on the machine parameters. Consequently, the R4 and R5 requirements are not complied with this method. From the point of view of post-fault control, the open- phase fault has been the most studied fault situation regardless of the control approach [22-25]. However, there is not a detection method of this fault type that https://doi.org/10.24084/repqj15.358 473 RE&PQJ, Vol.1, No.15, April 2017