Comprehensive Investigation on Remedial Operation of Switch Faults for Dual Three-Phase PMSM Drives Fed by T-3L Inverters

In this paper, the remedial operation of switch faults will be investigated comprehensively for T-type-three-level-inverter-fed dual three-phase motor drives. The open-circuit switch faults in multiple phase legs are discussed at first. The faulty conditions are classified into five categories. Different remedial strategies, namely Type-I to Type-V schemes, are proposed for different faulty conditions. In particular, three kinds of Type-III fault-tolerant control schemes are proposed by using medium-voltage vectors to synthesize small-voltage vectors, in such a way that the mid-point voltage in a dc link can be stabilized well. Then, the short-circuit faults in both clamping switches and half-bridge switches are investigated. By analysis, their operation conditions are equivalent to conditions loss of both P and N voltage levels and open-phase faults, respectively. Thus, the corresponding remedial strategies can be applied accordingly. Particularly, a voltage compensation control method is proposed for conditions, where open-switch faults coexist with open-phase operation induced by short-circuit faults in half-bridge switches. The validity of all of theoretical analysis and the proposed remedial strategies has been verified by experiments.