MS student Samith Sirimanna with advisor K. Haran
Typically, HVAC systems consume 36% of the total energy requirement for commercial buildings in the USA. Since the major power consumption in an HVAC system lies in the compressor motor, the requirement for having a high-efficiency motor is significant. This project, funded by Johnson Controls International PLC, is focused on designing and developing a 100kW high-efficiency motor for compressor applications and includes three main phases.
The first phase is a trade study on various motor types used in this application. Motor-drive system efficiency and cost are the two main selection criteria. Table 1 gives the Trade Study Summary of the chosen motor types. The second phase is to create a feasible design, build the prototype and test it. Several aspects are considered, including ac losses, mechanical stability at higher speeds and integrating the motor into a hermetic refrigerant environment. A cross-coupled electro-magnetic and mechanical optimization is implemented using Flux 12.1 and Creo software to find the optimum design. A number of motor dimensions, including slot geometry and bridge geometry of the interior permanent magnet rotor, are taken as variables and modified to find the best performance.
Table 1: Final Summary of Trade Study
|PMSM 2 pole||PMSM 4 pole||Induction 2 pole||PM assisted SynRM (NdFeB)||PM assisted SynRM (Ferrite)|
|IPLV Motor %||96.0%||95.8%||94.5%||96.1%||96.2%|
|IPLV VSD %||97.6%||97.0%||97.6%||97.0%||97.0%|
|IPLV Integrated %||93.6%||92.9%||92.2%||93.2%||93.3%|
|Motor Material Cost Index||0.303||0.233||0.089||0.126||0.088|
|Motor + VSD Material Cost Index||1.164||1.180||1.000||1.167||1.129|