Applicability Analysis of Indices-Based Fault Detection Technique of Six-Phase Induction Motor

Abstract

The multiphase induction motor is considered to be the promising alternative to the conventional three-phase induction motor, especially in safety-critical applications because of its inherent fault-tolerant feature. Therefore, the attention of many researchers has been paid to develop different techniques for detecting various fault types of multiphase induction motors, to securely switch the control mode of the multiphase drive system to its post-fault operation mode. Therefore, several fault detection methods have been researched and adapted; one of these methods is the indices-based fault detection technique. This technique was firstly introduced to detect open-phase fault of multiphase induction motors. The main advantage of this technique is that its mathematical formulation is straightforward and can easily be understood and implemented. In this paper, the study of the indices-based fault detection technique has been extended to test its applicability in detecting some other stator and rotor fault types of multiphase induction motors, namely, open-phase, open-switch, bad connection and broken rotor bar faults. Experimental and simulation validations of this technique are also introduced using a 1 kW prototype symmetrical six-phase induction motor.

A Comprehensive Survey on Fault Tolerance in Multiphase AC Drives, Part 1: General Overview Considering Multiple Fault Types

“…Broadly speaking, in case there is closed-loop current control ensuring zero steady-state current error at the VSD components affected by the imbalance, the detection algorithms rely on the voltage references (current-control output) [65][66][67][68]. Otherwise, if there is no current control with said capability, they normally monitor the dissymmetry of the measured currents [59,62,63,69]. As an exception, the methods focused on the zero sequence/s are based on measuring the zero-sequence voltage, provided the corresponding current cannot flow (isolated neutral points) [61].…”

“…In such conditions, the uncompensated x-y current and associated SCL may decrease the efficiency, but the torque is still smooth, provided space harmonics are negligible. Analogous indices are employed in [62] for a symmetrical six-phase IM, where phase OCs and broken rotor bars are diagnosed as well, although no details about the type of control are given.…”

“…From the preceding discussion, it can be concluded that most of the available methods for detecting high-resistance connections in multiphase drives are based, without extra hardware, on monitoring the current-measurement [59,[62][63][64]69] or voltage-reference [65][66][67][68] imbalance. The latter is more suitable when closed-loop current control is included at the unbalanced components for ensuring smooth torque (tolerance).…”

“…Some of these techniques are able to detect and distinguish other faults as well, such as phase/switch OC [62][63][64]69], stator SC [61], overheating [60], magnet demagnetization [68], and broken rotor bars [62].…”

“…Abdel-Mageed et al [85] show that an asymmetrical six-phase IM exhibits larger stator-current symptoms with one or two broken bars than a similar three-phase IM (analogously to, e.g., rotor slot harmonics; see Section 7.3.2.1); in addition, they propose to use neural networks for the fault detection. On the other hand, Farag et al [62] show that the indices used for detecting phase OCs or high-resistance connections (based on x-y current) are robust to bar breakage in a symmetrical six-phase IM, while the broken bars could be detected from the α 1 -β 1 or phase current spectrum as in a three-phase IM. 12.6.3.…”