Analysis and Implementation of HOT Standby Operation of Variable Frequency Drives

The main focus of this work is the study of various drive redundant operation possibilities. In this work, different techniques adopted in real time applications for drive redundancy operation are studied. Also drive redundancy operation carried out by various manufacturers are investigated and are included in the paper. The comparisons of various types of drive redundancy operations are also explained. Out of all these techniques, HOT STANDBY (HS) option of Variable Frequency Drives (VFD) is chosen and analyzed. Phase Locked Loop (PLL) techniques for analyzing the frequency and phase angle information of three phase signals are studied. Out of all the available three phase PLL, the appropriate PLL for this research is chosen and is implemented using Simulink environment. The chosen PLL is DDSRF-PLL which is used to check and correct drive synchronization dynamically. The proposed HS operation is implemented using Simulink and feasibility of the technique is studied. This setup is simplest and low cost design of HS option of VFDs.