Overall assessments of dual inverter open winding drives

Dual inverter open winding drive (DIOWD) has several advantages over standard 3 phase drive such as multilevel voltage output, lower dc link voltage, high efficiency and better fault tolerant capability. In this paper three DIOWD topologies aiming for high speed and/or safety critical applications are evaluated. Their operation characteristics, VA ratings, efficiencies, harmonic distortion factors (HDF) are quantitatively compared using analytical methods. The utilization of dual inverters provides fault tolerant capabilities for the drive. However, the doubled number of devices increases the risk of single-point failure. Finally, the reliability of the drives is assessed by Markov chain technique. The results show that the DIOWD with two power supplies exhibits low HDF and high efficiency; it also offers better fault tolerant capability and enhanced reliability, thereby being more attractive for both high speed and high reliability applications. While the DIOWD with single power supply and the DIOWD with a power supply and a floating capacitor can be utilized for high speed drives with reduced dc link voltage.