Open-switch fauli tolerant direct torque contol for voltage source inverter fed inducion motor drive system

Abstract

In many applications, such as nuclear reactors, aerospace, military applications, and life-saving machines, power electronic systems are considered one of the most important components. In such applications, the system must be highly reliable. All members of the drives community and marketplace are interested in the reliability of adjustable speed result, parallel redundancy is frequently used in these systems, albeit at a high cost. The electrical machines are supplied by AC-to-AC converters with an intermediate DC-link in many industrial drive applications. Different types of failures may occur at different levels of the AC drive system, such as the input rectifier, power inverter stage, which is of our interest in this thesis, or control sub-system. This work focuses on fault tolerant induction motor drive control in the event of VSI open-switch/leg failure. This system detects and isolates the fault, and then ensures the system's operation under the new conditions. This was accomplished using two different solutions:The first one was the redundancy-leg topology, which maintains the same control drive (Direct Torque Control) using a six-switch three-phase inverter (SSTPI). The second is a new switching technique for Direct Torque Control (DTC). This system modifies the DTC switching table using available stator voltage vectors in two phase mode with Four Switch Three Phase Inverter (FSTPI) topology to track the stator flux reference and directly control the torque and maintain the performance of the induction motor as in the Six Switch Three Phase Inverter (SSTPI) mode.