Fault tolerant control of permanent magnet synchronous motor traction module

Abstract

Subway applications can be handled by a fault-tolerant permanent-magnet module. Such modules are operated through normal, faulty and fault-tolerant control modes. In the first case (normal mode), 2 three-leg voltage-service inverters (VSIs) are set to respectively control 2 three-phase permanent-magnet synchronous machines (PMSMs). The intended maximum torque and velocity can be both achieved through the proposed module. In the case of the failure of one leg, the corresponding PMSM and the fault VSI are stranded from each other; consequently, the isolation mode becomes the operating field of the fault subway train. In such case, the main results are the reduction of the traction effort and the maintaining of maximum velocity under hight load. Never the less, the possible heaviness of the load may cause the shutdown of the fault subway train. In order to abstain the shut down, the fault-tolerant mode over takes the fault subway train; in such mode, a fault-tolerant bridge rearranges the healthy and the fault VSIs into a five-leg VSI. Regardless, unless velocity declines to half of maximum velocity, there cannot be a fault-tolerant mode because of the lower phase-phase voltage apportionment ratio. With the condition of a leg-failure, the proposed method can grant the subway train the ability to handle the basic operation performances. This paper includes the analysis of performances and the verification of its effectiveness.