An Improved Open Switch Fault Diagnosis Strategy for Variable Speed Drives

Abstract

Enhancing the reliability of modern industrial drives is critical as it enhances the drive’s availability and allows it to last longer. In electric drive system, the power devices are the most sensitive part, failure of these devices causes vibration and thermal stress on the machine. This article presents a reliable Park’s vector-based open circuit faults detection approach for 3-phase two-level voltage source inverters (2L-VSIs) to improve their operational performance. The proposed technique utilizes the normalized average value and the absolute average value of phase currents as fault indications. Despite transient load and speed circumstances, the empirically designed threshold value ensures independent fault detection in the power converter. The proposed diagnostic scheme can be further incorporated with a suitable fault reconfiguration structure to maintain the performance as drive normal operation. A 4-kW induction motor drive with 3-ph 2L-VSI is implemented in a Matlab/Simulink environment to validate the efficacy of the proposed diagnosis scheme.