Fault tolerant electric drives - solutions and current research activities, part II

Due to the steadily increasing computational power found in mechatronic components, more and more attractive functions besides integrated control can be realized. One of the most interesting supplementary functions is an integrated fault management, which allows the mechatronic component to detect and react to faults autonomously, subsuming under the term “fault-management”. Fault-tolerant control describes one such reaction, where the controller is e.g. reparameterized in the case of a fault to accommodate the fault induced changes of the system parameters. However, to achieve maximum fault mitigation, a fault tolerant system must reconfigure itself upon the detection of a fault which causes impairment or loss of an actuator part and/or sensor. The ability to be “fail-operational” can be achieved by engaging redundant hardware or by exploiting analytical redundancy upon the detection of a fault. This paper will concentrate on the current status and future research of electric drives, where part I focuses on the power electronics and part II on the electro-mechanical converter. In the area of electric drives many solutions have already been presented in the literature and shall be surveyed here. The reason for the prominent position of electric drives within the field of fault-tolerant drive concepts is twofold: First, the frequency converters used nowadays are typically employing micro-controllers so that information processing capabilities are already present. Secondly, the motors are composed of separate winding systems. The number of windings can easily be increased beyond the number necessary for the sole purpose of generating a rotating magnetic field with a uniform circumferential torque generation.