Open-Phase Fault Operation on Multiphase Induction Motor Drives

Multiphase machines have been recognized in the last few years like an attractive alterna‐ tive to conventional three-phase ones. This is due to their usefulness in a niche of applica‐ tions 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 multi‐ phase 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 ma‐ chines 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 chap‐ ter 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 openphase 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 de‐ tailed 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 openphase fault condition is managed using different control methods and the obtained re‐ sults are compared. Finally, the conclusions are presented in the last section of the chapter.