Compensation methods of interturn short-circuit faults in dual three-phase PMSM

Permanent magnet synchronous machines (PMSM) are widely used for their high efficiency and power density. High machine reliability is increasingly required nowadays. PMSMs can't be simply disconnected from the power source unlike asynchronous machines if any fault appears in the system. Many motor faults lead to malfunction of the whole system. This limitation can be solved by using multi-phase structures instead of commonly used three-phase structures. Multi-phase machines have many advantages in terms of high reliability. The power density of properly designed multi-phase system is also higher. The multi-phase PMSM can operate even during a fault, under certain conditions, depending on the motor parameters. The control algorithm must be capable to detect the fault and apply proper control method according to the detected fault. This paper demonstrates the behaviour of the dual three-phase PMSM motors under various inter-turn short circuit faults. An experimental PMSM was prepared, having stator windings with multiple taps. These winding taps are utilised to emulate inter-turn short circuit faults. The winding short-circuiting is realized by a solid-state relay. The fault influence is analysed on the experimental machine. Three compensation strategies are applied to reduce the fault influence. All compensation strategies are based on field weakening of the damaged motor part. The motor behaviour during the fault without compensation method is compared with the behaviour when using compensation strategies. Realised experiments demonstrate that a properly constructed dual three-phase PMSM under control with compensation strategies can continuously operate under the fault condition.