Fault Detection in Variable Phase-Pole Machines based on Harmonic Plane Decomposition

Abstract

Multiphase electrical machines have the inherent advantage of fault tolerance as compared to conventional threephase machines. A special category of multiphase electrical machines are variable phase-pole machines, which allow a change between phase-pole configurations without hardware reconfiguration, but merely through current control. This paper proposes an open-fault detection method for variable phase-pole machines; fast, non-invasive, parameter-and operation-independent. The method analyzes the space harmonics of the current distribution using the harmonic plane decomposition theory, which is already used to perform a seamless switch between phase-pole configurations. Simulation results demonstrate the feasibility of the approach.

Open Fault Detection in Variable Phase-Pole Machines Based on Harmonic Plane Decomposition

“…The proposed fault-detection algorithm can be applied in combination with the fault-tolerant controller in [29] minimizing the stator copper losses. This work is a continuation of the conference proceedings [30] with experimental data.…”

“…The proposed HPDFD's detection time has a lower boundary set by the amplitude threshold r th , the time hysteresis (t on /t of f ) from Section III-1 and the locking time t locked from Section III-2. In the theoretical analysis in [30], an instantaneous fault detection is achieved due the instantaneous spatial harmonics of the current distribution. Different to [20]- [24], [27], the underlying theoretical root of this algorithm does not require any averaging over a fundamental period T s nor a moving average over a pre-defined time T m .…”

Pole Transition Under Open Phase Fault Conditions in a Variable Pole Machine

“…In order to maintain constant torque production in the harmonic plane h = p and the additional constraint in (8), the reference currents require adaptation. While the current space vector īαβ0,h=p follows the same circular trajectory as in healthy state, the current space-vectors īαβ0,h̸ =p need to pulsate with the fundamental frequency in all the non-excited harmonic planes as it is shown in (9).…”

“…The pulsating īαβ0,h̸ =p has a dedicated direction with the angle ϑ h,k f as described in (10). This angle corresponds to the angle used for detection in [9].…”

“…For achieving true fault tolerance, first the OPF needs to be identified and localized. [9] proposed the harmonicplane-decomposition fault detection (HPDFD). It analyses the instantaneous spatial harmonics of the current distribution.…”