Research on Fault-Tolerant Control Strategy of Open-End Winding Drive With a Common DC Bus Under a Switch Open-Circuit Fault

Abstract

As the power core of a new energy vehicle, the operation reliability, especially the fault-tolerant operation ability of the electric drive system is directly related with the safety and user experience. The open-end winding topology with a common DC bus demonstrates many advantages and consequently attracts lots of attentions in the application of the new energy vehicles. However, most of existing fault-tolerant solutions for this topology, treat switch open-circuit fault as an open-circuit phase fault, which limits the system's fault-tolerant operation performance. Based on the analysis of the phase current and voltage characteristics after the switch open circuit fault, a fault-tolerant control scheme through biasing the fault-phase current is proposed in this paper, aiming to enhancing the load capability. Through this bias control the fault-phase current is only at one direction, i.e., positive or negative direction as expected, which allows the anti-parallel diode of the open-circuit switch be used to generate the voltage level desired. Therefore, the output voltage is not affected by the fault switch device. As found through mathematical calculation, both the output voltage and the output torque are increased greatly through the proposed fault tolerant scheme. At last, the effectiveness and advantages of proposed scheme is confirmed and demonstrated through experiments.